I-10 Twin Peaks Traffic Interchange, Environmental Assessment

Interstate 10 Traffic Interchange 

at Twin Peaks/Linda Vista 

ADOT Project No. NH-010-D(AIW) 

TRACS No. 10 PM 236 H5838 01D 

DRAFT 

ENVIRONMENTAL 

ASSESSMENT AND 

SECTION 4(f) 

EVALUATION 

October 2005 

Federal 

Highway 

Administration

Draft Environmental Assessment October 2005 

TABLE OF CONTENTS 

LIST OF ACRONYMS ...................................................................................................... x 

MITIGATION MEASURES ...........................................................................................xiii 

CHAPTER 1: INTRODUCTION...................................................................................1-1 

Explanation of Project...................................................................................................... 1-1 

Existing Roadway Network ....................................................................................1-4 

Other Modes of Transportation................................................................................ 1-6 

CHAPTER 2: PROJECT PURPOSE AND NEED ........................................................ 2-1 

Project Location............................................................................................................... 2-1 

Background and Overview .............................................................................................. 2-1 

Project Need.....................................................................................................................2-2 

Congestion Relief.................................................................................................... 2-2 

Drainage.................................................................................................................. 2-5 

Design Related Issues ............................................................................................. 2-6 

Connectivity............................................................................................................2-7 

Transportation System Connectivity.................................................................... 2-7 

Bicycle and Pedestrian Connectivity ...................................................................2-7 

Project Purpose ................................................................................................................2-8 

Conformance with Regulations, Land Use Plans, and Other Plans................................. 2-8 

General Project Schedule...............................................................................................2-10 

CHAPTER 3: ALTERNATIVES ...................................................................................3-1 

Alternative Corridor Evaluation ...................................................................................... 3-1 

TI Alternatives .................................................................................................................3-2 

Alternative TI Configurations................................................................................. 3-2 

Alternative TI Design Options - Twin Peaks Road Over or Under I-10 

and UPRR ...............................................................................................................3-4 

Alternative TI Alignments ......................................................................................3-6 

Alternatives Selected for Further Study......................................................................... 3-10 

No Build Alternative............................................................................................. 3-10 

Preferred Alternative............................................................................................. 3-11 

Proposed Roadway Improvements .......................................................................3-11 

Interstate 10 Traffic Interchange at 

Twin Peaks/Linda Vista 

i 

Project No.: NH-010-D (AIW) 

TRACS No.: 10 PM 236 H5838 01D


Proposed Intersection Improvements.................................................................... 3-17 

Proposed Lighting Improvements......................................................................... 3-20 

Proposed Bicycle and Pedestrian Facilities .......................................................... 3-20 

Proposed Drainage Improvements........................................................................ 3-22 

Proposed Santa Cruz River Channel Modifications ............................................. 3-25 

CHAPTER 4: AFFECTED ENVIRONMENT AND 

ENVIRONMENTAL IMPACTS.........................................................................4-1 

Land Use ..........................................................................................................................4-1 

Land Resources................................................................................................................ 4-4 

Topography.............................................................................................................4-4 

Soils.........................................................................................................................4-5 

Geologic Setting and Mineral Resources................................................................ 4-6 

Agriculture .............................................................................................................. 4-8 

Water Resources ..............................................................................................................4-9 

Surface Water.......................................................................................................... 4-9 

Ground Water........................................................................................................ 4-13 

Water Quality.................................................................................................................4-14 

Floodplains............................................................................................................4-14 

Section 404/401 of Clean Water Act .................................................................... 4-19 

NPDES/AZPDES/SWPPP....................................................................................4-21 

Sole Source Aquifer.............................................................................................. 4-22 

Biological Resources ..................................................................................................... 4-25 

Wildlife ................................................................................................................. 4-25 

Threatened/Endangered Wildlife Species.............................................................4-26 

Arizona Species of Concern.................................................................................. 4-33 

Plants..................................................................................................................... 4-34 

Threatened/Endangered Plant Species.................................................................. 4-34 

Arizona Native Plant Law Species .......................................................................4-35 

Vegetation, Riparian Habitat, and Wetlands......................................................... 4-36 

Invasive Species.................................................................................................... 4-40 

Visual Resources............................................................................................................ 4-41 

Air Quality .....................................................................................................................4-45 



ii 




Noise ............................................................................................................................4-49 

Hazardous Materials ...................................................................................................... 4-63 

Cultural Resources......................................................................................................... 4-66 

Socioeconomics .............................................................................................................4-77 

Demographics .......................................................................................................4-77 

Minority Groups/Title VI/Environmental Justice................................................. 4-81 

Neighborhood Continuity .....................................................................................4-82 

Emergency Services..............................................................................................4-82 

Social Services......................................................................................................4-83 

Relocations/Displacements................................................................................... 4-83 

Temporary Impacts ............................................................................................... 4-84 

Permanent Impacts................................................................................................ 4-86 

Section 6 (f) of the Land and Water Conservation Fund Act ........................................ 4-88 

Section 4(f) of the Department of Transportation Act................................................... 4-89 

Utilities and Railroad ..................................................................................................... 4-97 

Material Sources and Waste Materials ........................................................................ 4-100 

Construction Water Source.......................................................................................... 4-101 

Secondary Impacts.......................................................................................................4-101 

Cumulative Impacts ..................................................................................................... 4-102 

CHAPTER 5: PUBLIC INVOLVEMENT/PROJECT COORDINATION ...................5-1 

CHAPTER 6: CONCLUSION .......................................................................................6-1 

CHAPTER 7: PROJECT PREPARERS AND CONTRIBUTORS................................7-1 

CHAPTER 8: BIBLIOGRAPHY ...................................................................................8-1 

Appendices 

APPENDIX A: AGENCY SCOPING................................................................................. 

APPENDIX B: U.S. FISH AND WILDLIFE SERVICE CONSULTATION LETTERS . 

APPENDIX C: STAMINA MODELING RESULTS ......................................................... 

APPENDIX D: CULTURAL RESOURCES CONSULTATION LETTERS ................... 

APPENDIX E: SECTION 4(f) COORDINATION LETTERS .......................................... 

List of Tables 



iii 




Table 2-1. Comparison of 2030 Average Daily Traffic Volumes for Selected Roadway 

Segments With and Without Twin Peaks Road TI .................................................... 2-5 

Table 3-1. Existing and Proposed I-10 and Frontage Road Drainage Structures .......... 3-23 

Table 3-2. Proposed Twin Peaks Road and Linda Vista Boulevard Drainage 

Structures ................................................................................................................. 3-23 

Table 3-3. Existing and Proposed Channels Serving I-10 and Frontage Roads ............ 3-25 

Table 4-1. Proposed Property Acquisitions ..................................................................... 4-3 

Table 4-2. Proposed Additional Drainage Easements ..................................................... 4-4 

Table 4-3. Special Status Wildlife Species.................................................................... 4-27 

Table 4-4. Special Status Plant Species ......................................................................... 4-34 

Table 4-5. National and State Ambient Air Quality Standards ..................................... 4-46 

Table 4-6. 2002 Monitoring Data from Coachline Site compared to NAAQS ............. 4-47 

Table 4-7. Traffic Noise Monitoring Results..................................................................... 4-50 

Table 4-8. Noise Mitigation Evaluation Summary........................................................ 4-62 

Table 4-9. NRHP Eligibility Recommendations of Recorded Sites.............................. 4-74 

Table 4-10. 2000 Selected Census Data ........................................................................ 4-79 

Table 6-1. Summary of Environmental Assessment........................................................ 6-1 

List of Figures 

Figure 1-1. Project Location ............................................................................................ 1-2 

Figure 1-2. Study Area..................................................................................................... 1-3 

Figure 2-1. Levels of Service........................................................................................... 2-4 

Figure 3-1. Typical Roundabout Interchange .................................................................. 3-3 

Figure 3-2. Typical Diamond Interchange....................................................................... 3-3 

Figure 3-3. Typical Single Point Urban Interchange....................................................... 3-3 

Figure 3-4a. Alternative Alignments – North Alignment Alternative............................. 3-7 

Figure 3-4b. Alternative Alignments – Center Alignment Alternative ........................... 3-7 

Figure 3-4c. Alternative Alignments – South Alignment Alternative............................. 3-8 

Figure 3-5. No Build Alternative................................................................................... 3-10 

Figure 3-6. Preferred Alternative................................................................................... 3-11 

Figure 3-7. Proposed Twin Peaks Road Typical Section .............................................. 3-12 



iv 




Figure 3-8. Proposed Twin Peaks Road Bridge Crossing Over Santa Cruz River Typical 

Section...................................................................................................................... 3-12 

Figure 3-9. Proposed Twin Peaks Road Bridge Crossing over I-10 and the UPRR Typical 

Section...................................................................................................................... 3-14 

Figure 3-10. Proposed Access Road Typical Section.................................................... 3-14 

Figure 3-11. Proposed I-10 Eastbound Frontage Road and Ramps Typical Section..... 3-16 

Figure 3-12. Proposed I-10 Westbound Frontage Road and Ramps Typical Section ... 3-16 

Figure 3-13. Proposed Linda Vista Boulevard Typical Section..................................... 3-18 

Figure 3-14. Proposed Twin Peaks Road/Access Roadway Intersection 

Configuration ........................................................................................................... 3-18 

Figure 3-15. Proposed Twin Peaks Road/Eastbound Frontage Road Intersection 


Figure 3-16. Proposed Twin Peaks Road/Westbound Frontage Road Intersection 


Figure 3-17. Proposed Twin Peaks/El Camino De Mañana/Linda Vista Boulevard 

Intersection Configuration ....................................................................................... 3-20 

Figure 3-18. Proposed Twin Peaks Road Connection to Santa Cruz Shared Use Path. 3-21 

Figure 3-19. Proposed Drainage Facilities Near I-10 .................................................... 3-24 

Figure 4-1. Land Jurisdiction........................................................................................... 4-2 

Figure 4-2. Floodplains.................................................................................................. 4-17 

Figure 4-3. Jurisdictional Waters................................................................................... 4-20 

Figure 4-4a-d. Noise Analysis ................................................................. 4-53 through 4-56 

Figure 4-5. Census Tracts .............................................................................................. 4-78 

Figure 4-6. Acquisitions and Relocations...................................................................... 4-85 

Figure 4-7. Section 4(f) Resources ................................................................................ 4-91 



v 




List of Acronyms 

AASHTO American Association of State Highway and Transportation Officials 

ACHP Advisory Council on Historic Preservation 

ADA Americans with Disabilities Act 

ADEQ Arizona Department of Environmental Quality 

ADOA Arizona Department of Agriculture 

ADOT Arizona Department of Transportation 

ADT average daily traffic 

ADWR Arizona Department of Water Resources 

AGFD Arizona Game and Fish Department 

AMA Active Management Area 

ANPL Arizona Native Plant Law 

a.s.l. above sea level 

ASM Arizona State Museum 

AT&T AT&T Communications 

AZPDES Arizona Pollutant Discharge Elimination System 

BE Biological Evaluation 

BLM Bureau of Land Management 

BMP Best Management Practices 

CAAA Clean Air Act Amendments 

CEQ Council on Environmental Quality 

CFPO Cactus Ferruginous Pygmy-owl 

CFR Code of Federal Regulations 

CHU Critical Habitat Unit 

CMID Cortaro-Marana Irrigation District 

CO Carbon monoxide 

Corps U.S. Army Corps of Engineers 

CWA Clean Water Act 

dB decibel 

dBA A-weighted sound level in decibels 

DCR Design Concept Report 

DOI Department of the Interior 

EA Environmental Assessment 

EEG Environmental & Enhancement Group 

EO Executive Order 

EPA U.S. Environmental Protection Agency 

ESA Endangered Species Act 

FEA Final Environmental Assessment 

FEMA Federal Emergency Management Agency 

FHWA Federal Highway Administration 

FIRM Flood Insurance Rate Maps 



x 




FONSI Finding of No Significant Impact 

GMP General Management Plan 

I-10 Interstate 10 

I10F# Noise receiver location along I-10 and the frontage roads 

IO Isolated occurrence 

LWCFA Land and Water Conservation Fund Act 

Leq(h) Energy equivalent level over a one hour period 

LOS Level of Service 

LUST leaking underground storage tanks 

LVR# Noise receiver location along Linda Vista Boulevard 

MP Milepost 

mph miles per hour 

N/A not applicable 

NAAQS National Ambient Air Quality Standards 

NAC Noise Abatement Criteria 

NAP Noise Abatement Policy 

NEAP Natural events action plan 

NEPA National Environmental Policy Act 

NO2 

Nitrogen dioxide 

NPPO Native Plant Preservation Ordinance 

NPPP Native Plant Preservation Plan 

NPS National Park Service 

NR# Noise receiver located along the north side of Twin Peaks Road 

NRCS National Resources Conservation Service 

NRHP National Register of Historic Places 

O3 

Ozone 

PAG Pima Association of Governments 

PCDOT&FCD Pima County Department of Transportation and Flood Control District 

PDEQ Pima County Department of Environmental Quality 

PISA Preliminary Initial Site Assessment 

PM10 Particulate matter less than 10 microns in aerodynamic diameter 

PM2.5 Particulate matter less than 2.5 microns in aerodynamic diameter 

ppm Parts per million 

RAC rubberized asphaltic concrete 

RCBC reinforced concrete box culvert 

RCP reinforced corrugated pipe 

RS# Noise receiver location along the south side of Twin Peaks Road 

RTP Regional Transportation Plan 

R/W Right-of-way 

SDCP Sonoran Desert Conservation Plan 

SHPO State Historic Preservation Office 

SIP State Implementation Plan 

SNP Saguaro National Park 



xi 




SO2 

Sulfur dioxide 

SPUI Single Point Urban Interchange 

SR State Route 

SWPPP Storm Water Pollution Prevention Plan 

TAC Technical Advisory Committee 

TAPA Tucson Air Planning Area 

TEA-21 Transportation Equity Act for the 21 st Century 

TEP Tucson Electric Power 

TI traffic interchange 

TRDN Tres Rios del Norte 

UPRR Union Pacific Railroad 

U.S. United States 

USC United States Code 

USFWS U.S. Fish and Wildlife Service 

UST underground storage tanks 

VIR Visual Impact Rating 

Vpd Vehicles per day 

µg/ m 3 Micrograms per cubic meter 



xii 



Mitigation Measures October 2005 

MITIGATION MEASURES 

The following mitigation measures and commitments are not subject to change or 

modification without the prior written approval of the Federal Highway 

Administration. 

Town of Marana Responsibilities: 

1. The Town of Marana and the Arizona Department of Transportation would 

participate in an intergovernmental agreement, which would include the 

environmental mitigation contained within this document. 

2. The Town of Marana would widen the low flow channel of the Santa Cruz River 

to prevent an unacceptable rise in floodwater elevations within the 100-year 

floodplain. (Refer to page 4-19) 

3. During final design, the Town of Marana would give the local floodplain 

administrator the opportunity to review project plans. (Refer to page 4-19) 

4. The Town of Marana would obtain an individual Clean Water Act Section 404 

permit from the U.S. Army Corps of Engineers and Section 401 Water Quality 

Certification from the Arizona Department of Environmental Quality before 

construction commences. (Refer to page 4-21) 

5. To comply with Section 402, a Stormwater Pollution Prevention Plan would be 

prepared for this project by the Town of Marana. (Refer to page 4-22) 

6. Prior to construction, the Town of Marana would develop a revegetation plan that 

would incorporate the mitigation discussed below. (Refer to page 4-31) This 

revegetation plan would be provided to the contractor. Mitigation measures would 

include revegetation of impacted areas along the roadway and the riparian 

vegetation along the Santa Cruz River. Mitigation would include: 

• Disturbed soils would be re-seeded using species native to the project vicinity 

and would mirror the current plant composition to the extent possible. 

• Within upland areas, trees greater than 4 inches diameter at breast height and 

Saguaro cactus that are removed would be replaced within the overall 

construction footprint at a 3:1 ratio. Vegetation would be replaced in kind 

with a minimum container size of 15 gallons. These replacements would not 

occur within the clear zone of the roadway. 

• Within the clear zone of the roadway, creosote bush seed would be utilized in 

order to facilitate quick replacement of vegetation cover. 

• Mesquite trees greater than 4 inches diameter at breast height that are removed 

within the high flow channel of the Santa Cruz River would be replaced at a 

3:1 ratio within the overall project limits in accordance with the revegetation 

plan. Vegetation would be replaced in kind with a minimum container size of 

15 gallons. 



xiii 




• Riparian trees greater than 4 inches diameter at breast height that are removed 

for construction would be replaced in kind at a 3:1 ratio with a minimum 

container size of 15 gallons. 

• When fully restored, the vegetation within the Santa Cruz River would 

provide continuous tree cover through the project limits. 

• The bottom of the bridges would be approximately 20 feet above the bottom 

of the low flow channel of the Santa Cruz River, which should provide 

sufficient height to allow pygmy-owls and other wildlife to move unimpeded 

under the bridges. 

• The Town of Marana would provide water for all plantings outside the low 

flow channel of the Santa Cruz River for a period of two years to facilitate 

their establishment. 

• The Town of Marana would monitor all plantings for a period of two years, 

starting at the time of planting, on a quarterly basis. Two yearly reports would 

be generated and submitted to the U.S. Fish and Wildlife Service and the 

Arizona Department of Transportation’s Environmental and Enhancement 

Group discussing the progress of the revegetation effort. 

• The revegetation plan would comply with the Arizona Native Plant Law, and 

Native Plant Protection Ordinances of the Town of Marana and Pima County. 

In addition, the revegetation plan would also include U.S. Army Corps of 

Engineers recommended mitigation measures for the Santa Cruz River 

Channel. 

• The revegetation plan would be developed based on the objectives of the Tres 

Rio del Norte Feasibility Study. Tres Rio del Norte planning objectives related 

to vegetation on the Santa Cruz River include: creating a mesquite bosque at 

higher elevations from the Santa Cruz River bottom on terraces and over-bank 

areas; plant and establish cottonwood and willow tree plant communities 

along the wetted perimeter, and fringe area locations within the Santa Cruz 

River; established wetlands/Cienega at appropriate locations, to create a 

diverse and high value project habitat; and, reestablish desertscrub plant 

communities along the degraded upland portions of the Santa Cruz River 

corridor, emphasizing saltbush-wolfberry and mesquite associations as 

components. 

7. The Town of Marana would develop a Native Plant Protection Plan in accordance 

with local ordinances. (Refer to page 4-36) 

8. During design, a wetland delineation would be completed. In the event that 

jurisdictional wetlands are impacted by the preferred alternative, coordination 

with the U.S. Army Corps of Engineers would occur and appropriate permits 

would be obtained. (Refer to page 4-39). 

9. During final design, invasive species surveys would occur to determine if invasive 

species are present. (Refer to page 4-40) 



xiv 




10. Structural elements such as walls, bridges, concrete barriers, and abutments would 

be constructed of materials with color and texture qualities that blend into the 

existing landscape. Architectural treatments would be applied to the proposed 

Twin Peaks Road bridge over I-10 and other visible structures to enhance the 

driver’s perception of Marana and to be in accordance with similar projects on 

I-10 in the Tucson area. (Refer to page 4-44) 

11. Erosion control techniques such as slope rounding would be utilized, as 

necessary, to minimize impacts to visual quality. (Refer to page 4-45) 

12. Intersection lighting would be designed to minimize light pollution of night skies 

and limit glare into neighborhoods. (Refer to page 4-45) 

13. Methods of reducing headlight impact to residents of Continental Ranch would be 

considered in final design. (Refer to page 4-45) 

14. The need for sound mitigation walls would be reassessed during design. If walls 

would be required, the placement, type, and height would be determined during 

design. (Refer to pages 4-57) 

15. The Town of Marana would resurface Twin Peaks Road west to Silverbell Road 

with rubberized asphaltic concrete to decrease the noise generation from the tirepavement 

interface. (Refer to page 4-59) 

16. Before construction, the Town of Marana would conduct detailed Phase I Site 

Assessments to assess site-specific potential for hazardous materials issues on 

parcels rated as high and medium priority. Additional investigation may include, 

but is not limited to, additional site reconnaissance and interviews with current 

and historical property owners. If parcels to be acquired involve structures, 

following the acquisition of the structure but prior to its demolition, the structures 

would be assessed for asbestos, lead-based paint, and other hazardous materials in 

accordance with State and Federal regulations. (Refer to page 4-65) 

17. The Town of Marana would follow the terms and conditions of the Section 106 

programmatic agreement for I-10 improvements between the I-10/I-19 

interchange and Tangerine Road signed by SHPO, FHWA, ADOT, and the 

Advisory Council on Historic Preservation in 1993 (included in Appendix D) and 

subsequently amended. In addition, the Town of Marana would follow the SHPO 

recommendations to prepare a project specific treatment plan (see letter in 

Appendix D). (Refer to page 4-76) 

18. Minor gaps in the cultural resources inventory would be addressed by the Town 

of Marana as final design proceeds. These include completion of the archeological 

survey on parcels that could not be surveyed previously along the eastbound I-10 

frontage road and Linda Vista Boulevard because rights-of-entry could not be 

obtained. The Town of Marana would obtain archeological clearance before 

geotechnical testing for bridge and embankment piers. (Refer to page 4-76) 



xv 




19. The Town of Marana would provide plans for UPRR review to ensure that the 

project met current UPRR standards for bridge design and that the sequencing of 

construction minimized temporary disruptions to train traffic. (Refer to page 4-99) 

20. The Town of Marana would coordinate with the Cortaro-Marana Irrigation 

District prior to any modifications of the canal and construction would be 

coordinated so that the proposed improvements would not interfere with the 

supply of irrigation water during critical periods. (Refer to page 4-100) 

21. The Town of Marana would maintain utility coordination throughout the course 

of the project and schedules for any utility adjustments would be coordinated 

closely to minimize interruptions and inconvenience to customers. (Refer to page 

4-100) 

22. Utility clearances obtained by the Town of Marana would be in accordance with the 

Arizona Department of Transportation requirements. (Refer to page 4-101) 

Arizona Department of Transportation Tucson District Responsibilities: 

1. The Town of Marana and the Arizona Department of Transportation would 

participate in an intergovernmental agreement, which would include the 

environmental mitigation contained within this document. 

2. The Arizona Department of Transportation District Construction Office and the 

contractor will submit the Notice of Intent and the Notice of Termination to the 

Arizona Department of Environmental Quality and the Environmental Protection 

Agency. (Refer to page 4-22) 

Arizona Department of Transportation Environmental and Enhancement Group 

Responsibilities: 

1. To prevent damage to possible buried resources at the Stewart Brickyard 

archaeological site, a pre-construction testing plan would be developed and 

implemented for this site by the Town of Marana in consultation with Arizona 

Department of Transportation Environmental and Enhancement Group’s Historic 

Preservation Team. (Refer to page 4-76) 

Contractor’s Responsibilities: 

1. The terms and conditions of the Clean Water Act Section 404 permit from the 

U.S. Army Corps of Engineers and Section 401 Water Quality Certification from 

the Arizona Department of Environmental Quality would be followed by the 

contractor for work affecting jurisdictional waters within the project area. (Refer 

to page 4-21) 

2. The Arizona Department of Transportation District Construction Office and the 

contractor will submit the Notice of Intent and the Notice of Termination to the 

Arizona Department of Environmental Quality and the Environmental Protection 

Agency. (Refer to page 4-22) 



xvi 




3. The contractor would clean all earth-moving and hauling equipment prior to its 

entering the construction site to prevent the introduction of invasive species. 

(Refer to page 4-41) 

4. Erosion control techniques such as slope rounding would be utilized, as 

necessary, to minimize impacts to visual quality. (Refer to page 4-45) 

5. The contractor would monitor dust generation from the construction area and 

limit the amount of dust generated to a maximum opacity of 20 percent. (Refer to 

page 4-48) 

6. If relocation of asbestos-containing water lines is required, the contractor would 

handle, transport, and dispose of the material in accordance with approved federal, 

state, and county asbestos handling procedures. This would include appropriate 

precautions to ensure that employees are not exposed to airborne asbestos fibers 

and that fibers are not released into the atmosphere. (Refer to page 4-66) 



xvii 




Standard Specifications included as Mitigation Measures: 

1. Excess waste material and construction debris would be disposed of at sites 

supplied by the contractor in accordance with Arizona Department of 

Transportation’s Standard Specifications for Road and Bridge Construction 

Section 107.11 Protection and Restoration of Property and Landscape (2000 

Edition). Disposal would be made at either municipal landfills approved under 

Title D of the Resource Conservation and Recovery Act, construction debris 

landfills approved under Article 3 of the Arizona Revised Statutes 49-241 

(Aquifer Protection Permit) administered by the Arizona Department of 

Environmental Quality, or inert landfills. (Refer to page 4-12) 

2. During construction, the contractor would follow Arizona Department of 

Transportation’s Standard Specifications for Road and Bridge Construction, 

Section 104.09 Prevention of Landscape Defacement; Protection of Streams, 

Lakes and Reservoirs (2000 Edition) and the Water Quality Standards in Title 18, 

Chapter 11 of the Arizona Administrative Code as administered by the Arizona 

Department of Environmental Quality. (Refer to page 4-45) 

3. During construction, the contractor would control, reduce, remove or prevent air 

pollution in all its forms, including air contaminants, in the performance of the 

contractor’s work in accordance with Arizona Department of Transportation’s 

Standard Specifications for Road and Bridge Construction, Section 104.08 

Prevention of Air and Noise Pollution (2000 Edition). (Refer to page 4-48) 

4. During construction, the contractor would control construction noise in 

accordance with Arizona Department of Transportation’s Standard Specifications 

for Road and Bridge Construction, Section 104.08 Prevention of Air and Noise 

Pollution (2000 Edition). (Refer to page 4-57) 

5. According to Arizona Department of Transportation’s Standard Specifications for 

Road and Bridge Construction, Section 107 Legal Relations and Responsibility to 

Public (2000 Edition) (Stored Specification 107HAZMT, 01/15/93), if previously 

unidentified or suspect hazardous materials are encountered during construction, 

work would stop at that location and the Town of Marana Engineer would be 

contacted to arrange for proper treatment of those materials. Such locations would 

be investigated and proper action implemented prior to the continuation of work 

in that location. (Refer to Page 4-66) 

6. According to Arizona Department of Transportation’s Standard Specifications for 

Road and Bridge Construction, Section 107.05 Legal Relations and 

Responsibility to Public, Archaeological Features (2000 Edition), if previously 

unidentified cultural resources are encountered during activity related to the 

construction of the project, the contractor would stop work immediately at that 

location and would take all reasonable steps to secure the preservation of those 

resources and notify the Engineer. The Engineer would contact the Arizona 

Department of Transportation Environmental Planning Group, Historic 

Preservation Team (602.712.8636) immediately and make arrangements for the 

proper treatment of those resources. Arizona Department of Transportation 



xviii 




would, in turn, notify the appropriate agency(ies) to evaluate the significance of 

those resources. (Refer to page 4-76) 

7. Any material sources required for this project outside of the project area would be 

examined for environmental effects, by the contractor, prior to use, through a 

separate environmental analysis in accordance with Arizona Department of 


Section 1001 Material Sources (2000 Edition) (Stored Specification 1001.2 

General), unless the facility has received prior clearance from the Environmental 

and Enhancement Group of the Arizona Department of Transportation. (Refer to 

page 4-101) 



xix 



Introduction October 2005 

CHAPTER 1: INTRODUCTION 

This environmental assessment (EA) is being prepared to comply with the National 

Environmental Policy Act (NEPA) of 1969 and the policies of the Federal Highway 

Administration (FHWA), as the lead federal agency. The EA process provides steps and 

procedures to evaluate the potential social, economic, and environmental impacts of a 

proposed action while providing an opportunity for public and local, state, or other 

agencies to provide input and/or comment. In addition, this EA provides FHWA and the 

Arizona Department of Transportation (ADOT) a detailed analysis to better examine and 

consider the level of impacts on any sensitive social, economic, and environmental 

resources and assists in the decision-making process. 

A companion document to this EA has been prepared. The companion document is 

entitled Interstate 10 Traffic Interchange at Twin Peaks Road/Linda Vista Boulevard 

Initial Location Design Concept Report (DCR). The DCR is a document prepared for 

ADOT, which documents the design concept for proposed improvements, substantiates 

recommendations, documents alternatives considered, and identifies environmental 

effects. The DCR contains a higher level of engineering design detail than this EA and 

readers who desire that level of detail are referred to that document. 

Explanation of Project 

The existing Interstate 10 (I-10) traffic interchanges (TI) at Avra Valley Road and 

Cortaro Road are approximately four miles apart; therefore, the Town of Marana, as part 

of its Marana Master Transportation Plan, proposed a new major arterial roadway that 

would cross the I-10 Corridor in the vicinity of Twin Peaks Road and provide additional 

access to and from I-10. ADOT’s I-10 General Plan, Ruthrauff Road to Tangerine Road 

(General Plan) proposed the construction of a new I-10 TI in the vicinity of Twin Peaks 

Road, Linda Vista Boulevard, and El Camino de Mañana that would be an extension of 

the existing Twin Peaks Road in Marana. The General Plan also proposed a gradeseparated 

crossing of this roadway with the Union Pacific Railroad (UPRR) because only 

one other grade-separated railroad crossing (Orange Grove Road) existed between 

Ruthrauff Road and Tangerine Road. According to Pima Association of Governments’ 

(PAG) 2025 Regional Transportation Plan, the new TI and roadway would serve a 

substantial amount of traffic both crossing and accessing I-10. 

The proposed project would construct a new I-10 TI at Twin Peaks Road (hereinafter 

referred to as the Twin Peaks Road TI) approximately midway between the Avra Valley 

Road TI (milepost [MP] 242) and the Cortaro Road TI (MP 246) and would connect 

Twin Peaks Road on the west to El Camino de Mañana/Linda Vista Boulevard on the 

east. The proposed project location and vicinity are presented in Figures 1-1 and 1-2, 

respectively. 



1-1 



N 

95 

Yuma Yuma 

San Luis 

Hoover Dam 

Bullhead Bullhead City City 

95 

68 

Topock 

95 

95 

40 

Lake Lake Havasu Havasu City City 

95 

Ehrenberg 

95 

93 

L A P A Z 

Y U M A 

M O H A V E 

C O C O N I N O 

85 

85 

60 

8 

303 

89 

Y A V A P A I 

101 

M A R I C O P A 

Ajo Ajo 

Why 

Mobile Mobile 

Cottonwood 

Cottonwood 

Cordes Cordes 

Juction Juction 

10 

101 

87 

P I N A L 

202 

60 

Eloy Eloy 

P I M A 

287 

87 


89 

89 

87 

60 

87 

Page 

Parker Parker Payson 

Quartzsite Quartzsite 

Wellton Wellton 

Kingman Kingman 

Littlefield Littlefield 

Peach Springs 

STATE HIGHWAY SYSTEM 

OF 

ARIZONA 

ARIZONA DEPARTMENT OF TRANSPORTATION 

INTERMODAL TRANSPORTATION DIVISION 

0 25 50 75 100 

MILES 

72 

15 

8 

93 


60 

66 

40 

Colorado City 

97 

PROJECT NAME 

Seligman Seligman 

PROJECT NUMBER 

TRACS NO. 

71 

96 

389 

Wickenburg 

Wickenburg 

Gila Gila Bend Bend 

Ash Ash Fork Fork 

Chino Chino Valley Valley 

Prescott Prescott 

89 

85 

Lukeville 

Fredonia Fredonia 

Jacob Lake 

Grand Canyon 

86 

Clarkdale Clarkdale 

Jerome Jerome 

69 

74 

Phoenix Phoenix 

238 

64 

Prescott Prescott 

Valley Valley 

Williams Williams 

347 

89A 

17 

67 

North Rim 

Sedona Sedona 

51 

84 

180 

89A 

179 

Camp Camp 

Verde Verde 

587 

387 

Casa Casa 

Grande Grande 

386 

89 

Flagstaff Flagstaff 

87 

89 

88 

Coolidge 

Sasabe Sasabe 

Tuba 

City 

40 

Payson 

Superior 

Florence Florence 

86 

289 

Roosevelt Roosevelt 

Apache Apache Junction Junction 

Robles 

Junction 

286 

188 


160 

Leupp 

260 

Young 

Miami Miami 

Kearny 

79 

98 

87 

Winlsow 

Hayden Hayden 

19 

STATE MAP 

264 

99 

288 

77 

Mammoth Mammoth 

77 

Tuscon Tucson 

189 Nogales 

77 


40 

60 

264 

N A V A J O 

G I L A 

Sonoita 

Patagonia Patagonia 

99 

564 

Globe Globe 

Winkelman 

83 

SANTA 

CRUZ 

Kayenta Kayenta 

260 

Second 

Mesa 

87 

Joseph 

City 

377 

Snowflake 

82 

60 

70 


366 

266 

A P A C H E 

189 

A 

260 

G R A H A M 

Benson Benson 

90 

163 

277 

Sierra Sierra 

Vista Vista 

92 

160 

73 

Holbrook Holbrook 

77 

Taylor 

Fort Grant 

Bonita Bonita 

90 

Show Show Low Low 

Pinetop Pinetop 

80 

77 

Pima Pima 

Willcox Willcox 

Bisbee Bisbee 

Safford Safford 

Thatcher 

191 

Chinle 

Ganado 

Window 

Rock 

40 

191 

Bowie 

186 

191 

Eagar Eagar 

Clifton Clifton 

Sanders 

Alpine Alpine 

191 

GREENLEE 

Morenci Morenci 

C O C H I S E 

Tombstone 

Tombstone 

80 

191 

61 

473 

191 

191 

Teec Nos Pos 

180 

191 

273 

264 

St. St. 

Johns Johns 

181 

Douglas Douglas 

FIGURE 

160 

Springerville 

Springerville 

78 

61 

180 

San San 

Simon Simon 

80 

75 

Duncan Duncan 

70

AVRA VALLEY RD 

MARANA 

I-10 

SCENIC DR 

TWIN PEAKS RD 

Interstate 10 Traffic Interchange at Twin 

Peaks/Linda Vista 

MP242 

SILVERBELL RD 

COACHLINE BLVD 

TANGERINE RD 

WADE RD 

Study Area 

SANTA CRUZ RIVER 

EL CAMINO DE MAÑANA 

ARIZONA 

PAVILLIONS 

DRIVE 

CORTARO RD 

INA RD 

1-3 

LINDA VISTA BLVD 

MP246 

HARTMAN LN 

CAMINO DE OESTE 

CORTARO FARMS RD 

CAMINO DE OESTE 

TUCSON 

THORNYDALE RD 

LAMBERT LN 

OVERTON RD 

HARDY RD 

ORANGE GROVE RD 

Figure 1-2 

Study Area 

Project Number: NH-010-D (AIW) 



The Twin Peaks Road TI would be grade-separated with I-10 and with the UPRR and 

would include intersections with the I-10 eastbound and westbound frontage roads, and a 

newly constructed business access/circulation roadway. Twin Peaks Road would cross 

the Santa Cruz River on two new bridges (one eastbound and one westbound) and the 

I-10 eastbound frontage road, which is currently a two-way frontage road, would be 

converted to a one-way frontage road. The purpose and need for the project is described 

in the next chapter and the proposed improvements are described in greater detail in 

Chapter 3, Alternatives. 

The project area (the area where construction is expected to occur) occurs along I-10 at 

approximately MP 243. The project area will include slightly beyond the Twin Peaks 

Road tie-in on the west and slightly beyond the El Camino de Mañana/Linda Vista 

Boulevard intersection on the east. In addition, limited safety improvements are proposed 

along the I-10 frontage roads. 

The study area is a much larger area. Federal guidelines suggest that the study area be 

large enough to: 1) treat environmental issues on a sufficiently broad scope to ensure that 

the project will function properly without requiring additional improvements elsewhere; 

2) not restrict consideration of alternatives for other reasonably foreseeable transportation 

improvements; and, 3) give decision-makers and the public a clearer picture of the 

transportation requirements in the project area and a better understanding of the project 

purpose. 

Therefore, the study area is defined as the area between the Avra Valley Road TI on the 

north and the Cortaro Road TI on the south and the area between the intersection of Twin 

Peaks Road and Silverbell Road on the west and the intersection of Linda Vista 

Boulevard and Thornydale Road on the east. These termini were selected because the 

Twin Peaks Road TI would be expected to influence traffic within this area. 

Existing Roadway Network 

The FHWA Draft Classification Map, dated 2003, classified I-10 as an urban principal 

interstate roadway. In the area of the proposed Twin Peaks Road TI, I-10 provides two 

lanes in each direction with a wide median and a posted speed limit of 75 miles per hour 

(mph). According to PAG, average daily traffic (ADT) volumes on the roadway vary from 

52,100 vehicles per day (Vpd) north of the Avra Valley TI to 86,400 Vpd south of the 

Cortaro Road TI. Construction is underway on an I-10 widening project to add one 

through lane in each direction between the Tangerine Road and Cortaro Road TIs, which 

includes the Twin Peaks Road TI project area. 

The nearest TIs to the area of the proposed improvements include the Avra Valley Road 

TI, approximately 2 miles north of the Twin Peaks Road TI, and the Cortaro Road TI, 

approximately 2 miles south of the Twin Peaks Road TI. At the Avra Valley TI, a 

diamond interchange, the westbound I-10 ramps merge with a one-way, one lane 

roadway that parallels I-10. The eastbound I-10 ramps are separate from the two-lane, 

two-way frontage road that runs parallel to I-10. The two ramp intersections with Avra 

Valley Road are unsignalized. The Cortaro Road TI is also a diamond interchange. All 



1-4 




Cortaro Road TI ramps merge with two-lane, one-way frontage roads. Both I-10 ramp 

intersections with Cortaro Road are signalized. 

Frontage roads exist along both sides of I-10 in the vicinity of the Twin Peaks Road TI. 

The frontage road west of I-10 provides one lane in each direction allowing two-way 

travel from Avra Valley Road to Arizona Pavilions Drive (just north of the eastbound 

Cortaro Road off-ramp). The frontage road east of I-10 provides two lanes of one-way 

(westbound) travel from Cortaro Road to Avra Valley Road. 

Twin Peaks Road from Silverbell Road to its eastern terminus west of the Santa Cruz 

River is classified as an arterial roadway by the Town of Marana, but Pima County 

classifies Twin Peaks Road as a major collector. Twin Peaks Road is under the 

jurisdiction of and maintained by the Town of Marana. Twin Peaks Road consists of two 

travel lanes in each direction with a raised landscaped median, shared use lanes, curb, 

gutter, and sidewalk. The posted speed limit is 35 mph. Access along Twin Peaks Road is 

restricted to connecting roadways. Traffic counts are available only east of Silverbell Road, 

where ADT volumes on the roadway are approximately 10,700 Vpd. Volumes near the 

eastern terminus of Twin Peaks Road are considerably less. 

El Camino de Mañana from the I-10 westbound frontage road to Tangerine Road is 

classified as a collector roadway by the Town of Marana. Pima County classifies El 

Camino de Mañana from I-10 to Linda Vista Boulevard as an urban collector and a minor 

collector from Linda Vista Boulevard to Tangerine Road. El Camino de Mañana is under 

the jurisdiction of both the Town of Marana and Pima County, but is maintained by the 

Town of Marana through an intergovernmental agreement. The roadway provides one 

travel lane in each direction with no shared use lanes, curb, gutter, or sidewalks. The 

posted speed limit is 35 mph along El Camino de Mañana from I-10 to Tangerine Road. 

According to PAG, traffic volumes on El Camino de Mañana in this area reach 

approximately 500 Vpd. Access along El Camino de Mañana is unrestricted. El Camino de 

Mañana intersects with the I-10 westbound frontage road in an unlighted unsignalized 

“T”-intersection with stop-control on the El Camino de Mañana approach. El Camino de 

Mañana crosses the UPRR at-grade just east of its intersection with the I-10 westbound 

frontage road. El Camino de Mañana and Linda Vista Boulevard intersect in an unlighted 

unsignalized “T”-intersection with stop-control on the Linda Vista Boulevard approach. 

Linda Vista Boulevard from El Camino de Mañana to Thornydale Road is classified as a 

collector roadway by the Town of Marana. Linda Vista Boulevard west of Hartman Lane 

is under the jurisdiction of the Town of Marana while Linda Vista Boulevard east of 

Hartman Lane is under the jurisdiction of Pima County; however, Linda Vista Boulevard 

is maintained by Pima County through an intergovernmental agreement. West of Camino 

de Oeste, Linda Vista Boulevard provides one travel lane in each direction with no bike 

lanes, curb, gutter, or sidewalks. East of Camino de Oeste, Linda Vista Boulevard 

provides one travel lane in each direction with intermittent shared use lanes, curb, gutter, 

and sidewalks. The posted speed limit is 45 mph. Access along the roadway varies from 

unrestricted in the western portion to restricted in the eastern portion. According to PAG, 

traffic volumes on Linda Vista Boulevard vary from 400 Vpd near El Camino de Mañana 

to 7,700 Vpd near Thornydale Road. 



1-5 




Other Modes of Transportation 

The only continuous pedestrian and bicycle facilities (sidewalks 5 to 6 feet in width and 

paved shoulders of 6 to 8 feet in width) within the area are found along Twin Peaks Road 

from Silverbell Road to its eastern terminus. According to the PAG Tucson Bike Map, 

Twin Peaks Road from Silverbell Road to Coachline Road is designated as a Bike Route, 

while the roadway from Coachline Road to its eastern terminus is not designated. R17-3- 

407 of the Arizona Administrative Code prohibits bicycle use of I-10 in the vicinity of 

the Twin Peaks Road TI. 

Trails within the area are currently under design or construction. The Santa Cruz River 

Shared Use Path is under construction and will be a paved trail for bicycle and pedestrian 

use that will connect with other community trails and bikeways, facilitating nonmotorized 

access throughout the community and adjacent natural areas. This trail will 

follow the high flow channel of the Santa Cruz River and will cross Twin Peaks Road. 

The Marana segment of the De Anza National Historic Trail is under design and will 

follow and interpret the route of the 1775 De Anza expedition to San Francisco, 

California. This trail will be unpaved and suitable for equestrian use. The De Anza Trail 

will follow a circuitous route just outside the low flow channel of the Santa Cruz River 

and will connect with other equestrian trails that provide connections with nearby public 

open space and natural areas. 

Public transportation within the Town of Marana is provided by Sun Tran, the fixed bus 

route transit provider for the City of Tucson, and Pima County Rural Transit, the transit 

provider for unincorporated Pima County. Neither Sun Tran nor Pima County Rural 

Transit currently provides service stops in the vicinity of the Twin Peaks Road TI. A 

Greyhound Bus Lines station is located on Sandario Road near the Marana TI, 

approximately 8 miles north of the Twin Peaks Road TI 

Amtrak, which provides long distance intercity passenger rail service, passes through the 

Town of Marana. The only Amtrak station in Pima County is located at the Union Pacific 

Depot in downtown Tucson. The 1994 ADOT State Rail Plan Update identifies a future 

opportunity for providing a regional rail passenger system, which includes service 

between Tucson and Phoenix along I-10. 

The Union Pacific Transportation Company provides freight rail service along I-10 for 

the central and southern portions of the state. The UPRR line runs parallel to and east of 

I-10 in the vicinity of the Twin Peaks Road TI. 



1-6 



Project Purpose and Need October 2005 

CHAPTER 2: PROJECT PURPOSE AND NEED 

Project Location 

The proposed project involves the construction of a Twin Peaks Road TI on I-10 in the 

northwestern portion of the Tucson metropolitan area of Pima County, Arizona. The 

proposed project would occur primarily within the incorporated area of the Town of 

Marana, but also within the unincorporated area of Pima County. The Twin Peaks Road 

TI would be located approximately midway between the Avra Valley Road TI (MP 242) 

and the Cortaro Road TI (MP 246). 

Background and Overview 

Two studies, the Marana Master Transportation Plan completed in December 1989 and 

ADOT’s I-10 Design Concept Study (DCR), Ruthrauff Road to the Pima/Pinal County 

Line completed in 1990, recommended a new I-10 TI between the I-10 interchanges at 

Cortaro and Avra Valley Roads. Both studies recommended that the new I-10 TI connect 

Twin Peaks Road to El Camino de Mañana/Linda Vista Boulevard. The Marana Master 

Transportation Plan, the first transportation plan developed for the Town of Marana, 

recommended the TI as part of a planned parkway consisting of four- and six-lane 

arterials that encircled the Marana Town Center (near MP 236). The Marana Master 

Transportation Plan recommended two new TIs: a southern TI at Twin Peaks Road and a 

northern TI at Hardin Road (approximately MP 234). 

The ADOT I-10 DCR originally recommended the Twin Peaks Road TI to achieve 

desirable interchange spacing; however, as residential and commercial development 

increased in the area, the Twin Peaks Road TI was later seen as an important “reliever” 

for growing traffic congestion at the Cortaro Road TI. The DCR and the subsequent 

ADOT I-10 General Plan, Ruthrauff Road to Tangerine Road (1993) (General Plan) 

recommended a preliminary TI design which connected Twin Peaks Road and El Camino 

de Mañana and provided a grade separation with the Southern Pacific Railroad (now the 

UPRR). 

FHWA requires that additions or revisions of access to the interstate system be justified 

in a Change of Access Report. As a result of the recommendations of the General Plan, 

the Change of Freeway Access Report, I-10 Corridor Improvements General Plan 

Ruthrauff Road to Tangerine Road, dated December 1991, was completed. This report 

contained an analysis of a Twin Peaks Road TI. The additional point of access to I-10 at 

Twin Peaks Road was approved in a memorandum from FHWA Administrator T.D. 

Larson on June 26, 1992, subject to the State’s compliance with applicable Federal 

requirements. 

One of these Federal requirements was to analyze the social, economic, and 

environmental effects of the improvement alternatives recommended in the General 

Plan. The Final Environmental Assessment I-10 Corridor Improvements General Plan 

Ruthrauff Road to Tangerine Road assessed 12 miles of I-10 between Tangerine Road 



2-1 




(MP 240.4) and Ruthrauff Road (MP 252.4) in 1993 (hereinafter this document is 

referred to as the 1993 EA). Based on the social, environmental, and economic analyses 

in the 1993 EA, the FHWA issued a Finding of No Significant Impact (FONSI) on 

October 29, 1993. Although a FONSI determination allows a project to proceed to design 

and construction, funding limitations have prevented project advancement until now. 

Because of the time that has elapsed since the FONSI was issued and the changes in 

conditions that have occurred, new environmental investigations are required. 

The 1993 EA stated that the purpose and need for improvements to I-10 between 

Tangerine Road and Ruthrauff Road was to: 

• correct roadway, ramp, and frontage road deficiencies in design; 

• correct undesirable levels of service within certain segments of the interstate and 

at several interchanges; 

• provide future capacity and prevent operational issues relating to insufficient 

capacity; and, 

• improve safety in high volume interchange areas, freeway segments on which 

traffic demands are approaching capacity conditions, and other areas. 

The interest in a Twin Peaks Road TI has not waned. The first assumption in future 

growth projections developed for the transportation model used for the 2001-2025 

Marana Transportation Plan Update (Plan Update) was the construction of the Twin 

Peaks Road TI. At a public open house on the Plan Update in December 2000, the 

public’s highest transportation priority was to extend Twin Peaks Road to I-10 to relieve 

the congestion on Cortaro and Ina Roads. 

Project Need 

The Twin Peaks Road TI and associated improvements are needed to: 

• relieve existing and future congestion on Cortaro Road and Silverbell Road; 

• eliminate stormwater from the I-10 mainline and frontage roads; 

• correct issues related to roadways not meeting current design standards, and 

motor vehicle conflicts with the railroad; and, 

• improve bicycle and pedestrian and general transportation system connectivity. 

Each of these project needs is documented in detail in the following sections. 

Congestion Relief 

The need for a Twin Peaks Road TI has been discussed since the mid-1980s. Since that 

time, development patterns changed as a result of environmental restrictions. The major 

reason for these changing development patterns was the listing of the cactus ferruginous 

pygmy-owl (CFPO) as endangered in 1997. Much of the land considered highly desirable 

for residential development was located in habitat considered critical to the survival of 

the CFPO. As a result, the bulk of development shifted to areas outside those preferred by 



2-2 




the CFPO. Much of this development occurred within the Cortaro Road and Silverbell 

Road corridors. At the time the Plan Update was being completed, traffic congestion was 

concentrated along Cortaro Road, Ina Road, and Orange Grove Road in the vicinity of 

I-10 and at major arterial roadway intersections near retail centers. 

Congestion of roadways and intersections is measured by capacity analyses according to 

procedures contained in the 2000 Highway Capacity Manual. Capacity is defined by 

Level of Service (LOS) which is expressed as letters A to F (LOS A representing the best 

operating conditions and LOS F the worst). During morning and evening peak hour 

traffic, LOS D is considered acceptable for the urban situation characteristic of the area 

of the Twin Peaks Road TI. These LOS conditions are graphically depicted in Figure 2-1. 

At the time of the Plan Update, Cortaro Road suffered some of the poorest operating 

conditions of any arterial in the Town of Marana. Cortaro Road had the highest number 

of segments operating at LOS F (4) and the highest percentage of segments operating at 

LOS F (80%) within the Town of Marana. Since the Plan Update, Cortaro Road, Cortaro 

Farms Road, and Ina Road west of I-10 were widened and additional widening is planned 

for Cortaro Farms Road east of I-10. This would continue to provide congestion relief in 

the area, but because Cortaro Farms Road crosses the UPRR at-grade, frequent passing 

trains cause substantial delays to motorists. According to PAG, approximately 50 to 65 

UPRR trains pass through the area per day. 

Traffic forecasts for the year 2030 were developed for this project using the regional 

transportation demand model. This information is presented in Table 2-1. The 2030 

projected ADT volumes presented in Table 2-1 are developed from 24-hour traffic counts 

of existing traffic, projected development (both residential and employment) in the 

region, and proposed improvements to other roadways in the regional transportation 

network. The regional transportation demand model then forecasts traffic based on 

drivers selecting the paths of least resistance from projected origins (residential areas) to 

destinations (areas of employment and other destinations). According to the forecasts, a 

Twin Peaks Road TI would absorb a substantial amount of traffic from other roadways in 

the area. As shown in Table 2-1, 7,600 and 5,100 vehicles are displaced from Cortaro 

Road and Cortaro Farms Road west and east of I-10, respectively. However, Silverbell 

Road would experience the greatest relief. On Silverbell Road, 12,300 and 8,300 vehicles 

are displaced north and south of Cortaro Road, respectively. 

A grade-separation at the UPRR would prevent drivers from experiencing train-related 

delays on Twin Peaks Road and would reduce congestion on other local roadways. It is 

important to note that traffic impacts related to railroad crossings are difficult to analyze 

in both the traffic capacity software (which produces LOS) and the transportation demand 

model (which forecasts traffic). It is likely that the transportation demand model volumes 

presented in Table 2-1 underestimate the amount of traffic that the Twin Peaks Road TI 

would displace, because drivers would favor grade-separated railroad crossings over atgrade 

crossings. 



2-3 






Figure 2-1. Levels of Service. 

Courtesy of Logan Simpson Design, Inc. 

2-4 




Table 2-1. Comparison of 2030 Average Daily Traffic Volumes for Selected 

Roadway Segments With and Without Twin Peaks Road TI 

Roadway Segment (location) Without Twin 

Peaks Road TI 

With Twin Peaks 

Road TI 

Silverbell Road (north of Cortaro Road) 48,000 35,700 

Silverbell Road (south of Cortaro Road) 39,000 30,700 

Cortaro Road (west of I-10) 26,000 18,400 

Cortaro Farms Road (east of I-10) 27,000 21,900 

Drainage 

Standing water on a roadway can cause vehicle hydroplaning and a subsequent loss of 

control resulting in a vehicle crash; therefore, removing the water that falls on or flows 

across roadways is important to public safety. To determine the drainage conditions 

within the general area of the Twin Peaks Road TI, a drainage study was conducted. 

The drainage conditions were summarized in the Interstate 10 Traffic Interchange at 

Twin Peaks/Linda Vista, Final Drainage Report, dated May 21, 2004. According to the 

Drainage Report, some of the watersheds that drain to the area near the Twin Peaks Road 

TI originate in the Tortolita Mountains approximately 12 miles to the northeast. Runoff 

flows from the mountains are impeded by the embankment for the UPRR tracks. In 

general, the UPRR tracks are higher in elevation than both the westbound frontage road 

and I-10 mainline, but the I-10 mainline is higher in elevation than the westbound 

frontage road. Of the 17 drainage structures under the UPRR, 16 are undersized for the 

50-year rainfall event; therefore, during these events, ponding at these structures may 

occur. Water that cannot move through the structures, continues to flow northwest along 

the UPRR embankment to the next drainage structure. This pattern is consistent within 

the area of the Twin Peaks Road TI and continues beyond the limits of the Twin Peaks 

Road TI. 

Drainage structures are located also under the I-10 frontage roads and I-10 mainline (16 

culverts under the westbound frontage road and 12 under I-10) to allow water to drain to 

the Santa Cruz River. The drainage pattern at these structures follows that of the UPRR: 

flows that are not conveyed under I-10 and its frontage roads by undersized drainage 

structures continue to the northwest along the roadway. Generally there is adequate 

drainage capacity to prevent the 50-year rainfall event from ponding on the I-10 frontage 

roads and mainline because of a combination of: 1) the metering of flows to the roadways 

by the UPRR drainage structures; 2) the capacities of the I-10 frontage road and I-10 

mainline drainage structures; and, 3) the capacities of the roadside ditches which transmit 

flows along the roadways to the northwest. In one area north of the Twin Peaks Road TI 

and one location south of the Twin Peaks Road TI, however, runoff exceeds the capacity 

of this system. In these locations, water can flow over the westbound frontage road and 

the I-10 mainline during the 50-year rainfall event. 



2-5 




Drainage improvements are needed to the I-10 mainline and frontage road drainage 

structures to prevent runoff from flowing over the mainline and frontage road and 

possible vehicle hydroplaning. 

Design Related Issues 

The existing roadway system does not meet current design standards and crosses the 

UPRR tracks at-grade. These issues are discussed in the following paragraphs. 

Frontage Roads 

Frontage roads exist along both sides of I-10 in the vicinity of the Twin Peaks Road TI. 

The westbound frontage road provides two lanes of one-way travel from Cortaro Road to 

Avra Valley Road. The frontage road west of I-10 provides two lanes of one-way travel 

eastbound only from Arizona Pavilions Drive (just north of the eastbound Cortaro Road 

off-ramp) to Cortaro Road. From Arizona Pavilions Drive north to Avra Valley Road, the 

west side frontage road allows two-way travel with one lane in each direction. 

In accordance with the General Plan, ADOT has been systematically converting I-10 

frontage roads from two-way to one-way operation in the Tucson area. The frontage road 

from Arizona Pavilions Drive north to Tangerine Road is the last remaining segment of 

two-way I-10 frontage road in the Tucson metropolitan area. As a result, this segment of 

frontage road operates differently than other segments in the Tucson area. These 

operational differences may confuse drivers who expect one-way frontage road operation 

and, as traffic volumes increase, the potential for head on collisions and crashes typical of 

vehicles slowing to make turns (e.g., rear end crashes) increases; therefore, conversion of 

the two-way frontage road on the west side of I-10 to a one-way eastbound frontage road 

is needed to promote better operations and to comply with ADOT policy. 

The two-way frontage road interferes also with proper interstate frontage road operation. 

According to the 1991 Change of Access Report, the frontage road system is intended to: 

1) provide direct and reasonable access to properties adjacent to the frontage roads; 2) 

provide arterial service to supplement corridor capacity; 3) preserve the interstate 

character of the freeway by encouraging drivers making short trips to use the frontage 

road; 4) facilitate local circulation; and, 5) provide a parallel facility for temporary 

diversion of freeway traffic during maintenance, construction, or freeway closures. These 

functions cannot be adequately met with two-way operation of the eastbound frontage 

road. 

The frontage roads do not meet current clear zone design guidelines. The American 

Association of State Highway and Transportation Officials’ (AASHTO) Roadside Design 

Guide (1996) recommends a clear zone or recovery zone adjacent to roadways. This clear 

zone will allow a vehicle that has left the roadway to recover and return to the roadway 

without colliding with roadside obstacles. Clear zone widths are based upon roadway 

design speed, traffic volumes, and slopes adjacent to the roadway. The frontage roads 

have a relatively high speed limit (55 mph), relatively flat slopes, and traffic volumes 

between 1,600 and 3,500 Vpd. The Roadside Design Guide recommends a clear zone 

width of approximately 25 feet under these conditions. Along the westbound frontage 

road, concrete headwalls of irrigation structures are within approximately 6 feet of the 



2-6 




roadway. Along the eastbound frontage road, numerous structures such as utility poles, 

mailboxes, and other obstructions encroach within the recommended clear zone. To meet 

AASHTO guidelines, obstructions within the clear zone should either be removed or an 

energy absorbing barrier placed between the obstruction and the roadway. 

Railroad Conflicts 

At-grade railroad crossings are a concern. At-grade railroad crossings have a higher 

potential for serious vehicle/train accidents than do grade-separated railroad crossings. 

Currently El Camino de Mañana and Cortaro Road both cross the railroad at-grade. 

Although waiting for a train to pass an at-grade crossing is an inconvenience to most 

motorists, it can pose time delays to emergency response personnel. Northwest Medical 

Center, at an early public agency scoping meeting for this project, stated that the at-grade 

crossings may result in extended delays for emergency medical personnel trying to reach 

patients on the west side of I-10 and transporting them to hospital facilities on the east 

side of I-10. These delays may be critical to some patients. 

Connectivity 

Transportation System Connectivity 

Lack of access to destinations east of I-10 limits circulation within the area. The TIs at 

Avra Valley Road and Cortaro Farms Road are approximately four miles apart. The 

Town of Marana, as part of the Plan Update and ADOT, as part of the DCR Ruthrauff 

Road to the Pima/Pinal County Line, both determined the need for a new major arterial 

roadway that would cross the I-10 Corridor in the vicinity of Twin Peaks Road. In the 

PAG Regional Transportation Plan, the Twin Peaks Road TI and roadway was projected 

to serve a substantial amount of traffic both crossing and accessing I-10. 

Bicycle and Pedestrian Connectivity 

Within the study area, there are few pedestrian and bicycle amenities. According to the 

Plan Update, on-street bicycle lanes and paved shoulders throughout the Town of 

Marana are generally isolated facilities that do not interconnect with the surrounding 

network. Within the area, pedestrian and bicycle amenities are provided only on Twin 

Peaks Road from Silverbell Road to its eastern terminus. According to the Plan Update, 

all new collector and arterial roadways should include sidewalks 6 feet in width on both 

sides of the roadway to accommodate pedestrians, especially people with disabilities. The 

Plan Update suggests also that new arterial roadways at a minimum include shared use 

paths on one side of the roadway within the right-of-way. 

The Town of Marana’s General Plan Update promoted alternative modes of 

transportation and park and ride lots and stated that the connection of a paved system of 

bicycle and pedestrian trails to the region’s Santa Cruz River Corridor system was of 

importance. To improve connectivity to the Santa Cruz River Shared Use Path and other 

facilities on both sides of I-10, improvements to bicycle and pedestrian facilities within 

the area of the Twin Peaks Road TI are needed. 



2-7 




Project Purpose 

The purpose of the proposed project is to address each of the needs identified above. The 

proposed project would: 

• Improve traffic operations on the area’s transportation network by providing an 

additional access point to I-10 and a grade-separated crossing of the UPRR; 

• Correct drainage deficiencies on the I-10 mainline and frontage roads; 

• Address design related issues by: eliminating an existing at-grade railroad 

crossing; providing a new grade-separated railroad crossing; improving the 

consistency of frontage road traffic operations; improving the I-10 frontage roads’ 

clear zones to current design guidelines; and, 

• Improve overall connectivity of all modes of transportation within the area, 

including pedestrians and bicycles. 

The proposed improvements that would fulfill the project purposes are discussed in detail 

in Chapter 3, Alternatives. 

Conformance with Regulations, Land Use Plans, and Other 

Plans 

Proposed improvements should conform to currently adopted transportation and land use 

plans and zoning ordinances. This section discusses the compatibility of the proposed 

project with existing regulations, land use plans, and other plans. 

Town of Marana General Plan Update 

The General Plan Update was adopted by the Marana Town Council in November 2002 

as a broad collection of goals, policies, and implementation strategies that provide overall 

direction for future growth and development. The General Plan Update stated that the 

Twin Peaks Road TI was essential to establish proper arterial spacing and to distribute 

I-10 loading. The Twin Peaks Road TI improvements and frontage road traffic flow 

adjustments were anticipated also to enhance economic development along the I-10 

Corridor. The General Plan Update promoted alternative modes of transportation and 

park and ride lots and stated that the connection of a paved system of bicycle and 

pedestrian trails to the region’s Santa Cruz River Corridor system was of importance. 

Marana Transportation Plan Update, 2001-2025 

The Transportation Plan Update, which updated the original 1989 plan, was adopted in 

July 2001. According to the Transportation Plan Update, a large portion of the Town of 

Marana’s population will be concentrated near Continental Ranch; therefore, construction 

of the Twin Peaks Road TI by 2010 was noted as a critical component of the traffic 

growth forecasts. The Transportation Plan Update contained also recommendations for 

transportation modes other than roadways and discussed the importance of 

interconnecting these facilities. On-street bicycle lanes, shared use lanes or paved 

shoulders, and sidewalks were proposed on all new or reconstructed arterial and collector 



2-8 




roadways. At Transportation Plan Update open houses, the highest roadway priorities 

were to extend Twin Peaks Road to I-10 to relieve Cortaro and Ina Roads and to provide 

more grade-separated crossings of the UPRR or re-route the railroad. 

2025 Regional Transportation Plan (RTP) 

PAG developed the RTP to guide long range improvements to bus, roadway, bicycle, 

pedestrian, aviation, and rail transportation systems in the eastern Pima County region. 

The RTP is the result of a multi-jurisdictional planning effort consisting of the Town of 

Oro Valley, City of South Tucson, City of Tucson, Pascua Yaqui Tribe, Pima County, 

Tohono O’Odham Nation, Town of Marana, Town of Sahuarita, and the Arizona State 

Transportation Board. As a result, the RTP is the best representation of the transportation 

needs for eastern Pima County. The Twin Peaks Road TI is contained in the RTP. 

Town of Marana Santa Cruz River Corridor Plan 

The 2001 Santa Cruz River Corridor Plan contained several goals pertinent to the Twin 

Peaks Road TI, including: 1) develop a Santa Cruz River corridor plan that reflected the 

character of the community; 2) integrate planning for the Santa Cruz River corridor with 

related planning activities; 3) assist in efficiently providing infrastructure needs; and, 4) 

facilitate planning for the De Anza National Historic Trail, including the trail itself, 

access, interpretive facilities, and historic De Anza campsites. According to the Santa 

Cruz River Corridor Plan, seriously inadequate transportation crossings of the Santa 

Cruz River, railroad, and I-10 complicated efforts to unite the community on opposite 

sides of these features. The heavily traveled at-grade railroad crossings at Ina Road, 

Cortaro Road, and Tangerine Road were noted as major safety concerns and increasingly 

severe congestion problems. The Santa Cruz River Corridor Plan recommended also two 

trails along the Santa Cruz River corridor: the Santa Cruz River Shared Use Path and the 

Marana segment of the De Anza National Historic Trail. 

Continental Ranch Specific Plan 

The Specific Plan was first adopted in April 1988 and has been amended 8 times through 

2002. The Specific Plan established comprehensive guidance and regulations for the 

2,400-acre Continental Ranch development. The Specific Plan was regulatory and 

adopted by Town of Marana ordinance. The transportation circulation concept plan 

within the Specific Plan established the transportation system layout for the area 

(including Twin Peaks Road) and stated that residents from the development would 

initially access I-10 at Cortaro Road and in the future they would access I-10 at Twin 

Peaks Road. A Twin Peaks Road extension across the Santa Cruz River was illustrated in 

the circulation maps. The Specific Plan recommended bicycle and pedestrian trails along 

roadways and open space corridors. 

Town of Marana Park, Trail, and Open-Space System Master Plan 

The Park Plan, dated July 2000, was developed to identify community needs for parks, 

trails, and open space and provide a long-range plan for meeting these needs. The Park 

Plan map showed a “Twin Peaks Road District Park” near the intersection of Twin Peaks 

Road and Silverbell Road and the “Linda Vista Boulevard District Park” north of the El 

Camino de Mañana/Linda Vista Boulevard intersection. Although the Linda Vista 



2-9 




Boulevard District Park was drawn over part of El Camino de Mañana, the map stated 

also, “location approximate”. A proposed local trail (Scottie’s Loop Trail) appeared to 

cross both El Camino de Mañana and Linda Vista Boulevard near the intersection. 

Final Tres Rios del Norte (TRDN) Feasibility Study 

This study was completed in August 2001 as a coordinated effort between the Corps, 

Pima County, the City of Tucson, and the Town of Marana. The purpose of the TRDN 

Feasibility Study was to provide water resource and ecosystem improvements within the 

Santa Cruz River channel. The TRDN Feasibility Study consisted of several distinct parts, 

but its planning objectives were to: 1) increase habitat values and function of native plant 

and wildlife species identified in Pima County’s proposed Sonoran Desert Conservation 

Plan (SDCP); 2) attract wetland and riparian avian species identified in the SDCP; 3) 

facilitate wildlife movements for species identified in the SDCP; 4) establish the presence 

of amphibian species, reptilian species, mammalian species, and avian species in the area; 

5) control or manage non-native, invasive plant species in the area; and 6) restore natural 

Santa Cruz River flow paths. The TRDN Feasibility Study described several 

implementation measures that would address the planning objectives. Some of these 

measures included: 1) create mesquite bosque at higher elevations from the Santa Cruz 

River bottom on terraces and over-bank areas; 2) establish cottonwood and willow tree 

communities along the wetted perimeter and fringe area locations within the Santa Cruz 

River; 3) create wetlands/Cienega at appropriate locations; 4) incorporate trails and other 

passive recreational features in support of the other restoration management measures; 

and, 5) reestablish desertscrub plant communities along the degraded upland portions of 

the Santa Cruz River corridor. 

Additional discussion of these and other plans, proposed and adopted, may be found in 

later chapters of this document. In general, however, the transportation and land use 

elements of all plans discussed above were consistent with and supported the proposed 

Twin Peaks Road TI and associated improvements. 

General Project Schedule 

Environmental studies and development of design concepts for the Twin Peaks Road TI 

began in the Summer 2003. Environmental clearance for the proposed improvements is 

estimated to be obtained in 2006. Final Design for the proposed improvements is 

projected to begin in 2006 with an estimated completion of design in 2007. Construction 

of the Twin Peaks Road TI is projected to begin in 2007 with an estimated completion in 

2009. 



2-10 



Alternatives October 2005 

CHAPTER 3: ALTERNATIVES 

Chapter 3 describes the project alternatives, including the preferred alternative and the no 

build alternative. The analysis of alternatives was documented in the Interstate 10 Traffic 

Interchange at Twin Peaks/Linda Vista Alternatives Selection Report, dated May 3, 2004. 

Although readers are referred to the Alternatives Selection Report for a more thorough 

discussion, the results of the analyses are summarized here. 

Alternative Corridor Evaluation 

A series of analyses were applied to improvement alternatives considered for this project. 

These analyses began with very simple qualitative criteria and progressed through a 

series of successively more detailed analyses as the alternatives were refined. The first 

analysis was to determine if a proposed alternative met the project purpose and need as 

defined in the previous chapter. If the alternative met the purpose and need, it was 

advanced for additional study, if it did not, it was eliminated from additional 

consideration. 

Both the 1989 Marana Master Transportation Plan and ADOT’s 1990 I-10 Design 

Concept Study, Ruthrauff Road to the Pima/Pinal County Line recommended a new I-10 

TI between the I-10 interchanges at Cortaro and Avra Valley Roads. This location served 

the Town of Marana’s objective to serve as part of a planned parkway system and 

achieved ADOT’s goals for desirable interchange spacing and for traffic congestion relief 

at the Cortaro Road TI. 

During the Public Open House of October 20, 2003, several individuals suggested that 

the new interchange with I-10 be constructed north of Twin Peaks Road; therefore, this 

alternative corridor was considered early in the analysis of alternatives. It was found that 

the construction of a new TI north of Twin Peaks Road would have two major 

disadvantages: 1) it would not provide proper interchange spacing along I-10; and, 2) it 

would not adequately relieve traffic on Cortaro Road and Silverbell Road. 

According to AASHTO’s A Policy of Geometric Design of Highways and Streets (2001) 

(AASHTO Green Book), interchange spacing has a pronounced effect on freeway 

operations. A general rule of thumb for minimum interchange spacing is 1 mile from onramp 

to off-ramp in urban areas. Placement of an interchange north of Twin Peaks Road 

would result in less than recommended spacing between the ramps of the new 

interchange and the Avra Valley Road TI ramps. A grade-separated railroad crossing at 

the Twin Peaks Road TI location would produce desirable spacing of approximately five 

miles between grade separated railroad crossings at the Prince Road/La Cholla Road, 

Orange Grove Road, and Twin Peaks Road TIs. 

A TI has been recommended at the approximate location of Twin Peaks Road for many 

years because of the desirable design characteristics discussed above and because many 

trips originate and end in Continental Ranch and the surrounding area. If the TI were 

constructed north of Twin Peaks Road, Continental Ranch residents would be required to 

drive farther to access the new TI. As a result, the TI would be used less, and congestion 



3-1 




and safety on Cortaro Road and Silverbell Road would not be improved sufficiently. For 

these reasons, an alternative corridor north of Twin Peaks Road would not meet the 

project purpose and need and was eliminated from further consideration. 

TI Alternatives 

After meeting the purpose and need analysis, alternatives were subjected to a more 

detailed level of analysis. Several different alternatives were selected for additional 

analysis. These included alternative TI configurations, alternative TI design options, and 

alternative TI alignments. Each of these are discussed below. 

Alternative TI Configurations 

Several alternative TI configuration options were considered during the study, including a 

roundabout traffic interchange, a tight diamond interchange, and a Single Point Urban 

Interchange (SPUI). Each of these configuration options is discussed below. 

Alternative TI Configurations – Roundabout Traffic Interchange 

A roundabout traffic interchange consists of a circular intersection in which entering 

traffic yields to circulating traffic. The intersection is not signalized. Entering traffic aims 

at the central island and is deflected slowly around it. These characteristics may increase 

the capacity of the intersection, reduce maintenance costs, slow traffic speeds, and may 

reduce the frequency and severity of crashes. A typical roundabout interchange is 

presented in Figure 3-1. 

Recently ADOT has considered roundabout intersections as possible alternatives for 

intersections of crossroads and frontage roads. Roundabouts have been constructed on 

freeway corridors in the Phoenix metropolitan area and were considered at the request of 

the Technical Advisory Committee for the Twin Peaks Road TI. Because the 

intersections of the crossroad and frontage roads at the proposed interchange would be 

elevated on fill, the construction of roundabouts on one or both sides of I-10 would 

present substantial design and construction challenges and would require additional rightof-way 

acquisition from property owners (including the railroad) in excess of that 

required by a tight-diamond interchange. As a result, the roundabout was eliminated from 

additional consideration. 

Alternative TI Configurations – Tight Diamond Interchange 

The diamond interchange is one of the most prevalent TI designs and is commonly used 

throughout Arizona. A full diamond is formed when a one-way diagonal ramp (either an 

on-ramp or off-ramp) is provided in each quadrant of the interchange. The ramps 

terminate at the crossroad and at-grade left turns are confined to the crossroad. The 

diamond interchange has several advantages: traffic can enter and leave the major road at 

relatively high speeds; left-turning maneuvers entail little extra travel; and, a relatively 

narrow right-of-way is needed. A typical diamond interchange is presented in Figure 3-2. 



3-2 




Figure 3-1. 

Typical Roundabout Interchange 



Figure 3-3. 

Typical Single Point Urban Interchange 

3-3 

Figure 3-2. 

Typical Diamond Interchange 




Alternative TI Configurations - Single Point Urban Interchange 

The SPUI is a form of diamond interchange with a single signalized intersection through 

which all left turns utilizing the interchange must travel. Right turns into and out of ramp 

approaches are generally free flow. SPUIs are typically characterized by narrow right-ofway, 

higher construction costs, and greater capacity than conventional tight diamond 

interchanges. The primary operational advantage of the SPUI is that vehicles making 

opposing left turns pass to the left of each other rather than to the right, so their paths do 

not intersect. A typical SPUI is presented in Figure 3-3. 

The SPUI interchange configuration with one-way frontage roads would result in reduced 

operational efficiency and increased delays compared to the diamond configuration. This 

operational difficulty would be exacerbated by accommodating pedestrian movements. 

As a result, the SPUI was eliminated from additional consideration and a tight diamond 

interchange was selected as the preferred interchange configuration. 

Alternative TI Design Options - Twin Peaks Road Over or Under I-10 and 

UPRR 

After a tight diamond interchange configuration was selected, the method of crossing 

I-10 and the UPRR was the next issue to be considered. The new roadway could either 

cross over I-10 and the UPRR on bridge structures or could pass under I-10 and the 

UPRR as a depressed facility. At the Public Open House held on October 20, 2003, 

several individuals suggested that the underpass design option be considered, because this 

design is in place at the I-10/Orange Grove Road TI. 

The underpass option was considered previously in the Change of Freeway Access 

Report, I-10 Corridor Improvements General Plan Ruthrauff Road to Tangerine Road, 

dated December 1991. The Change of Freeway Access Report preferred the over design 

because it: 1) provided the greatest flexibility in allowing corridor improvement to take 

place without being dependent on interchange improvements; 2) minimized right-of-way 

acquisition; and, 3) provided a grade separated UPRR crossing, which would minimize 

future traffic delays and improve safety. 

To determine if the preferred design option selected in the Change of Freeway Access 

Report was still valid, the over and under design options were compared using design 

characteristics, social, economic and environmental affects, estimated costs, and ease of 

construction. The results of this analysis are presented below by design option. 

Alternative TI Design Options - Twin Peaks Road Under I-10 and UPRR 

The underpass option had several major disadvantages, including: 

• A temporary relocation of the current railroad alignment would be required 

and disruption of train traffic would result; 

• Utilities between the railroad and I-10 mainline would require relocation, 

including underground petroleum lines, which would be especially difficult 

and expensive to relocate. 



3-4 




• Shallow groundwater (60 feet below ground surface) would require 

dewatering (removal of shallow groundwater) during construction and regular 

dewatering of the underpass after construction could be required. 

• To convey stormwater runoff collected in the underpass to the Santa Cruz 

River, pumping facilities would be required, which would result in higher 

personnel and maintenance costs. 

• The underpass would require 24-hour roadway lighting for security, traffic 

safety, and to accommodate pedestrian and bicycle traffic. 

• To accommodate the eventual shift in the I-10 mainline alignment 

recommended in the I-10 General Plan, an I-10 bridge over Twin Peaks Road 

would need to be excessively wide. To accommodate the future elevation 

increase proposed for the I-10 mainline in the I-10 General Plan, 

reconstruction of the I-10 mainline to match the change in elevation at the 

bridge would be required. The excess bridge width and reconstruction of the 

I-10 mainline would add considerable costs to the Twin Peaks Road TI. 

Advantages of the underpass option included: 

• Relocation of overhead electric transmission lines and support structures 

would not be required. 

• Twin Peaks Road would pass under I-10; therefore, there would be less visual 

effects to users of I-10. In addition, an underpass would be less visible, 

although the bridge over the Santa Cruz River would still be visible. 

• Less traffic noise would be expected to emanate from a depressed structure 

than an elevated structure; therefore, traffic noise mitigation could be less 

extensive. 

Alternative TI Design Options - Twin Peaks Road Over I-10 and UPRR 

Disadvantages of the overpass option included: 

Advantages: 

• Train traffic could be disrupted during placement of the bridge deck and 

possibly other phases of railroad bridge construction. 

• The overpass structures would be visible from I-10 and to area residents. 

• More traffic noise would be expected to emanate from an elevated structure 

than a depressed structure; therefore, traffic noise mitigation could be more 

extensive. 

• Less disruption to train traffic would be expected than with the underpass 

alternative. 

• Users of the bridge would experience a greater range of views. 

• The bridge structure would offer the opportunity for public art treatments 

visible from I-10 and at greater distances. 



3-5 




• Relocation of underground utilities between the railroad and I-10 mainline 

would not be extensive. 

• Pumping facilities would not be required to convey stormwater runoff to the 

Santa Cruz River. 

• Less extensive roadway lighting would be required. 

• Construction of a bridge would not be expected to involve extensive 

dewatering of groundwater during and after construction. 

• Eventual I-10 mainline realignment could be accommodated by bridge design 

without reconstruction of the existing I-10 mainline. 

The disadvantages of the underpass design option were considered much more substantial 

than those of the overpass design option; therefore, the overpass option was selected as 

the preferred design option. As a result, the design option of Twin Peaks Road crossing 

under both I-10 and the UPRR was eliminated from further consideration. 

Alternative TI Alignments 

After selecting a tight diamond interchange with a Twin Peaks Road overpass of I-10 and 

the UPRR, alternative alignments for the overpass were developed. The range of 

alignment alternatives was defined and each alignment alternative was compared based 

on design characteristics, social, economic and environmental affects, cost, and 

constructability. 

The range of alternative alignments was framed by required or desirable design 

characteristics. For this project, a set of design criteria was established for the I-10 

mainline, the Twin Peaks Road TI and ramps, and approaching roadways (Twin Peaks 

Road, Linda Vista Boulevard, and El Camino de Mañana). Roadway design criteria 

contained in the ADOT Roadway Design Guidelines were used for the design of 

freeways, frontage roads, ramps, cross roads, and other roadway infrastructure within 

ADOT right-of-way. All other roadways used design criteria contained in the Pima 

County Roadway Design Manual. The north and south alignment limits were established 

by applying the Twin Peaks Road design speed of 50 mph and the corresponding 

maximum allowable roadway curvature; therefore, three alternative alignment 

alternatives were evaluated: north, center, and south alignments. These alignments are 

presented in Figures 3-4A-C. 

The roadway design was complicated by the proximity of the UPRR tracks to the 138 

kilovolt transmission line towers east of I-10 (approximately 150 feet apart), which 

forced the design to “thread the needle” between the two structures (avoiding the 

relocation of the transmission line towers was considered desireable). Railroad safety 

standards require that the bottom of the bridge crossing the UPRR be a minimum of 23 

feet above the railroad track surface and the Electric Safety Code requires a minimum of 

22 feet of clearance between the overhead transmission lines and the roadway to provide 

safe vehicle passage below the lines. Because the transmission lines sag between towers, 

alignments were located close to the towers to meet the required vertical clearance. 



3-6 






Figure 3-4. Alignment Alternatives 

A. North Alignment Alternative 


B. Center Alignment Alternative 

3-7 





C. South Alignment Alternative 

The Twin Peaks Road TI alignment alternatives had many similarities. These included: 

• All would construct a new four-lane divided roadway that would connect the end 

of Twin Peaks Road, west of the Santa Cruz River with a new signalized 

intersection of Linda Vista Road and El Camino de Mañana. 

• The I-10 frontage roads would be reconstructed to accommodate the Twin Peaks 

Road TI and the existing two-way segment of the eastbound frontage road would 

be converted to one-way operation. 

• The I-10 frontage roads within the Twin Peaks Road TI limits would be 

constructed in accordance with the ultimate improvements outlined in the I-10 

General Plan. All alternatives would extend the I-10 right-of-way west to 

accommodate the eventual shift in alignment of the I-10 mainline. 

• Drainage improvements would be provided to protect the roadways against 

flooding. ADOT, Pima County, and Town of Marana requirements for safe and 

efficient roadway design would be included in each alternative. 

All alignment alternatives would construct also a two-way supplemental access road to 

compensate partially for the effects of right-of-way acquisition and the loss of access near 

the proposed Twin Peaks Road TI. Currently businesses in the area depend on access to 

the eastbound frontage road and this access would be either eliminated or modified with 

the construction of the Twin Peaks Road TI. According to ADOT’s Roadway Design 

Guidelines, access onto the frontage roads should be prohibited from slightly beyond the 

ramp/frontage road intersection through the intersection with the cross road (Twin Peaks 



3-8 




Road). Prohibiting access in this area would minimize conflicts between low speed 

vehicles turning into and out of driveways with traffic exiting and entering the interstate 

at high speeds. The two-way circulation roadway around the west side of these properties 

would allow properties near the Twin Peaks Road TI to access Twin Peaks Road directly 

and I-10 and the frontage roads indirectly after frontage road access would be eliminated 

(see access road in Figures 3-4A-C). 

The alignment alternatives were presented to the businesses surrounding the proposed TI 

on March 12 and 15, 2004 and to the general public on March 22, 2004. Almost no 

support was expressed for the north alignment. Many participants stated a preference for 

roadway alignments with fewer curves and a straighter alignment of Twin Peaks Road, 

but no clear preference between the central and the south alignments was demonstrated. 

The analysis of alternative alignments was documented in the Alternatives Selection 

Report prepared for this project. Although readers are referred to the Alternatives 

Selection Report for a more thorough discussion, the results of the analyses are 

summarized here. 

• The Center Alternative had the lowest construction costs. 

• The Center Alternative required four fewer acres of additional right-of-way and 

fewer total property takes. 

• The Center Alternative exhibited the most desirable design characteristics. 

• The Center Alternative exhibited the most favorable environmental 

characteristics. These included: 

� least visual affects; 

� least displacement of habitat in the low flow and high flow channels of 

the Santa Cruz River; 

� least displacement of wetlands; and, 

� avoided documented cultural resources. 

As documented in the Alternatives Selection Report, the center alignment was selected to 

be carried forward for detailed analysis in the EA and design phases of the project. This 

alternative was selected because: it was the least cost alternative and minimized 

additional right-of-way acquisition and total property takes; it exhibited the most 

desirable design characteristics; it did not exhibit substantial disadvantages in comparison 

to the north and south alignments; and, it was generally preferred by the affected property 

owners and the public. 

Subsequent to the selection of the center alignment as the preferred alignment, design 

changes were required. The UPRR proposed to add a second track on the east side of the 

existing track and to increase the elevation of the added track above that of the existing 

track. In addition, revised traffic projections indicated that additional traffic lanes on the 

bridge over the UPRR may be needed. As a result, the height of the bridge over the UPRR 

was adjusted and the bridge width was increased to accommodate more traffic lanes at a 

later time. These design changes made it impossible to “thread the needle” between the 

UPRR tracks and the TEP towers. As a result, the relocation or the raising of one or more 

of the transmission line towers would be required. However, relocation or raising one or 



3-9 




more of the transmission line towers would be required for all of the alignment 

alternatives and would not influence the selection of center alignment alternative. 

The proposed improvements associated with the preferred alignment and the no build 

alignment are discussed below. 

Alternatives Selected for Further Study 

No Build Alternative 

The no build alternative would not construct an additional interchange on I-10, would not 

extend Twin Peaks Road, El Camino de Mañana or Linda Vista Boulevard to I-10, would 

not eliminate the at-grade crossing of the UPRR at El Camino de Mañana, would make 

no safety improvements to the I-10 frontage roads in the area, would not acquire 

additional right-of-way in the study area, and would not convert the two-way frontage 

road along the west side of I-10 to a one-way frontage road. No improvements would be 

made to any of the affected roadways except for those activities currently planned and 

programmed and routine maintenance. As a result, existing and future deficiencies in 

roadway design, roadway congestion on Cortaro Road and Silverbell Road, stormwater 

flowing over the I-10 mainline and frontage roads, motor vehicle conflicts with the 

railroad, and bicycle, pedestrian, and general transportation system connectivity 

deficiencies would continue. Current trends of declining traffic operations and increasing 

crashes would be expected to continue also. The no build alternative is illustrated in 

Figure 3-5. 



Figure 3-5. No Build Alternative 





Preferred Alternative 

Constructing a Twin Peaks Road TI with I-10 as a tight diamond interchange along the 

center alignment was selected as the preferred alternative. The specific improvements 

associated with this alternative are discussed below and illustrated in Figure 3-6. 

Proposed Roadway Improvements 

Twin Peaks Road 

Figure 3-6. Preferred Alternative 

A new four-lane divided roadway would be constructed that would connect Twin Peaks 

Road, west of the Santa Cruz River, with a new signalized intersection of El Camino de 

Mañana and Linda Vista Road on the east side of I-10. A typical section (a slice across the 

roadway) of Twin Peaks Road would consist of 11-foot wide inside lanes and 12-foot 

wide outside lanes, as shown in Figure 3-7. Shoulders 7 feet in width that may be used by 

bicycles and a 6-foot wide sidewalk would be provided on both sides of the roadway. A 

raised center median that varies in width would be provided along most of Twin Peaks 

Road. The median would not be provided where the roadway crosses the Santa Cruz 

River, because directional traffic would be separated onto two bridge structures. The total 

right-of-way width would vary between 200 and 300 feet. This roadway section would be 

maintained through the intersection with Linda Vista Boulevard and then transition to a 

two-lane section to match the existing roadway section of El Camino de Mañana. 



3-11 






Figure 3-7. Proposed Twin Peaks Road Typical Section (a slice across the roadway) 

Figure 3-8. Proposed Twin Peaks Road Bridge Crossing over the Santa Cruz River Typical Section 

3-12 




Twin Peaks Road would cross the Santa Cruz River, I-10, and the UPRR on bridge 

structures. The roadway would approach the Santa Cruz River on both sides on 

embankment and then cross the Santa Cruz River on twin bridge structures of 

approximately 750 feet in length. A typical section of the Twin Peaks Road bridge 

crossing of the Santa Cruz River is shown in Figure 3-8 and would consist of 11-foot 

wide inside lanes and 12-foot wide outside lanes. Shoulders 7 feet in width that may be 

used by bicycles and a 6-foot wide sidewalk would be provided on both sides of the 

roadway. The sidewalk would be physically separated from the shoulder by a concrete 

barrier 32 inches in height. The bottom of the bridge would be approximately 20 feet 

above the low flow channel of the Santa Cruz River. 

Twin Peaks Road would rise again on embankment approaching I-10 from the west and 

approaching the UPRR tracks from the east. The roadway would cross I-10 on a bridge of 

slightly over 200 feet in length approximately 24 feet above the exiting I-10 roadway 

surface. According to the I-10 General Plan, the elevation of I-10 would be raised in this 

area; therefore, after the modifications to I-10, the bottom of the bridge would be slightly 

over 17 feet above the I-10 roadway surface. A typical section of the Twin Peaks Road 

bridge crossing of I-10 and the UPRR is shown in Figure 3-9. 

Twin Peaks Road would cross over the UPRR tracks on a bridge approximately 130 feet 

in length. The UPRR plans to add an additional track on the east side of the existing track 

(double track) to increase the capacity of the line; therefore, the bridge length would 

accommodate the additional future track. The bottom of this bridge would be 23.5 feet 

above the track surface to meet railroad safety standards. The roadway would approach 

the railroad on embankment on both sides. The embankment would continue to the east 

until the roadway matched the existing terrain, approximately 750 feet east of the UPRR. 

The existing surface of Twin Peaks Road through Continental Ranch is in fair to poor 

condition. The pavement shows signs of low to medium severity deterioration, rutting, 

and various types of cracking such as block, longitudinal, and transverse cracking. This 

project proposes to mill and resurface Twin Peaks Road to Silverbell Road with 

rubberized asphaltic concrete (RAC) which would improve drivability of the roadway. 

An RAC surface also decreases the noise generation from the tire-pavement interface. 

Although the FHWA will not participate in the funding of roadway resurfacing with 

RAC, the Town of Marana will provide the funding for this rehabilitation. 

Access Road 

The two-way supplemental access road was proposed to partially mitigate the effects of 

the potential additional right-of-way acquisition and the loss of access near the Twin 

Peaks Road TI. The access road would connect the I-10 eastbound frontage road north 

and south of the Twin Peaks Road TI and intersect with Twin Peaks Road, east of the 

Santa Cruz River. A typical section of the access road would consist of a two-lane 

roadway with 12-foot wide travel lanes and 10-foot wide shoulders, 6 feet of which 

would be paved. The total right-of-way width would be 150 feet. A typical section of the 

access road is shown in Figure 3-10. 



3-13 






Figure 3-9. Proposed Twin Peaks Road Bridge Crossing over I–10 and the UPRR 

Figure 3-10. Proposed Access Road Typical Section 

3-14 




I-10 Frontage Roads 

New two-lane, one-way frontage roads would replace the current frontage roads near the 

Twin Peaks Road TI. The frontage roads would be positioned in accordance with the 

planned future improvements to I-10 specified in the General Plan and the 1993 EA. The 

eastbound frontage road would be reconstructed and relocated approximately 100 feet west 

of its existing location in accordance with the proposed future I-10 widening to 8 lanes and 

proposed I-10 on and off ramps. Proposed right-of-way acquisition for this project would 

be sufficient to accommodate these roadway improvements. The westbound frontage road 

would be reconstructed in the vicinity of the Twin Peaks Road TI to accommodate the 

grade-separated TI structure and to accommodate the I-10 on and off ramps; therefore, 

additional right-of-way would not be acquired along the east side of I-10. 

Typical sections of the frontage roads and ramps are shown in Figures 3-11 and 3-12. The 

typical section would consist of two lanes, each 12 feet in width with 8-foot inside and 

outside shoulders. The new frontage roads would have a posted speed limit of 45 mph. 

Stop sign control would be provided on the frontage roads just prior to merging with the 

I-10 off-ramps. The eastbound frontage road would be converted to one-way operation 

from the Avra Valley TI south to the Cortaro Road TI and would result in one-way 

frontage road operation from the Avra Valley TI to the 29 th Street TI. 

Encroachments into the clear zone of the existing frontage roads would be addressed with 

the proposed improvements. Additional right-of-way acquisition in the area of the 

proposed reconstruction and relocation of the eastbound frontage road would allow 

recommended clear zone widths to be provided. Along the westbound frontage road, 

concrete headwalls of irrigation structures are within approximately 6 feet of the roadway. 

A cost-benefit analysis of the clear zone obstructions along the westbound frontage road 

and beyond the area of eastbound frontage road reconstruction would be conducted. 

Depending on the results of this analysis, obstructions within the clear zone would either 

remain, be removed, or an energy absorbing barrier (i.e. guardrail) would be placed 

between the obstruction and the roadway. 


Modifications proposed to the I-10 mainline are limited to transitions into and off the 

roadway in both directions to serve the Twin Peaks Road TI on and off ramps. Although 

no other modifications to the I-10 mainline are proposed as a part of this project, the 

proposed improvements would be designed in accordance with the completion of the 

mainline improvements specified in ADOT’s I-10 General Plan and the 1993 EA. 

El Camino de Mañana 

The preferred alternative would remove the at-grade crossing of El Camino de Mañana 

with the UPRR. The roadway east of the UPRR would be retained for access to the Tucson 

Electric Power (TEP) transmission line and towers in the area and to provide access to 

adjacent properties. The proposed improvements would reconstruct the intersection of 



3-15 

Project No.: NH-010_D (AIW) 





Figure 3-11. Proposed I-10 Eastbound Frontage Road and Ramps Typical Section 

Figure 3-12. Proposed I-10 Westbound Frontage Road and Ramps Typical Section 

3-16 




Linda Vista Boulevard and El Camino de Mañana approximately 500 feet northeast of its 

current location and straighten the roadway. As a result, a portion of the existing El Camino 

de Mañana north of the existing intersection with Linda Vista Boulevard would be 

abandoned. 

Linda Vista Boulevard 

The preferred alternative would reconstruct Linda Vista Boulevard from its new 

intersection with El Camino de Mañana for approximately 0.7 miles to the east. The 

roadway and subgrade would be reconstructed as a two-lane all weather roadway section 

with 12-foot wide travel lanes, and 10-foot wide shoulders, 6 feet of which would be 

paved and may be used by bicycles. A typical section of Linda Vista Boulevard is shown 

in Figure 3-13. Sidewalks would not be provided along Linda Vista Boulevard because: 

(1) the proposed roadway would not be provided with curb; therefore, pedestrians would 

not be separated from vehicles by the curb and unsafe conditions for pedestrians would 

result; (2) the addition of sidewalk now would require replacement whenever roadway 

improvements to Linda Vista Boulevard occur; (3) the area is characterized by low 

density residential development; and, (4) as the area develops, the Town of Marana will 

require developers to construct the sidewalk. New right-of-way would be acquired within 

the area proposed for reconstruction to produce a total right-of-way width of 150 feet. 

Linda Vista Boulevard east of the tie-in point would not be modified. The roadway 

structure is adequate to withstand the higher traffic volumes caused by the project, but the 

design life of the roadway may be reduced; therefore, the roadway may require more 

frequent maintenance. 

Proposed Intersection Improvements 

Twin Peaks Road/Silverbell Road/Scenic Drive is an unsignalized, unlighted intersection 

with stop sign control on the Twin Peaks Road and Scenic Drive approaches. The 

westbound (Twin Peaks Road) approach provides single dedicated left-turn and right-turn 

lanes and one through lane, while the eastbound approach (Scenic Drive) provides a 

single lane. The northbound Silverbell Road approach provides a dedicated left-turn, 

right-turn, and a single through lane, while the southbound approach provides one 

through lane and a dedicated left-turn lane. According to the Traffic Report, projected 

peak hour traffic volumes for the implementation year (2008) are projected to merit 

signalization; therefore, a traffic signal at this intersection would be provided. 

Twin Peaks Road/Coachline Boulevard is an unsignalized, unlighted intersection with 

four-way stop control. All approaches provide a dedicated left-turn lane and two through 

lanes. According to the Traffic Report, projected peak hour traffic volumes for the 

implementation year (2008) are projected to merit signalization; therefore, a traffic signal 

at this intersection would be provided. 

Twin Peaks Road would meet the two-way access road at a signalized intersection. The 

lane configuration of the proposed Twin Peaks Road/access road intersection is shown in 

Figure 3-14. This intersection would be illuminated and bicycle striping would be carried 

through the intersection. Crosswalk and pedestrian actuated signals would be provided. 



3-17 






Figure 3-13. Proposed Linda Vista Boulevard Typical Section 

Figure 3-14. Proposed Twin Peaks Road/Access Road Intersection Configuration 

Twin Peaks 

Road 

Access Road 

3-18 




Twin Peaks Road would form signalized intersections with the I-10 frontage roads east 

and west of I-10. The lane configurations of the proposed intersections of Twin Peaks 

Road with the eastbound and westbound frontage roads are shown in Figures 3-15 and 

3-16, respectively. Both intersections would be illuminated and bicycle striping would be 

carried through the intersection. Crosswalk and pedestrian actuated signals would be 

provided. 

Figure 3-15. Proposed Twin Peaks Road/Eastbound Frontage Road Intersection 

Configuration 


Road 

I-10 Eastbound frontage road 

Figure 3-16. Proposed Twin Peaks Road/Westbound Frontage Road Intersection 

Configuration 


Road 



I-10 Westbound frontage road 

3-19 




The preferred alternative would construct a new Twin Peaks Road/El Camino de 

Mañana/Linda Vista Boulevard signalized intersection approximately 650 feet northeast 

of the existing El Camino de Mañana/Linda Vista Boulevard intersection. The proposed 

intersection configuration is shown in Figure 3-17. This intersection would be illuminated 

and bicycle striping would be carried through the intersection. Crosswalk and pedestrian 

actuated signals would be provided. Past the intersection, the roadway would transition to 

a two-lane roadway to match the existing section of El Camino de Mañana. 

Figure 3-17. Proposed Twin Peaks/El Camino De Mañana/Linda Vista Boulevard 

Intersection Configuration 

El Camino De Mañana 

Twin Peaks Road 

Proposed Lighting Improvements 

Linda Vista 

Boulevard 

New intersection lighting would be provided at all signalized intersections within the 

study area. These include the intersections of Twin Peaks Road and Silverbell Road, 

Coachline Boulevard, the access road, the Twin Peaks Road and the I-10 eastbound and 

westbound frontage roads, and the Twin Peaks Road/El Camino de Mañana/Linda Vista 

Boulevard intersection. In addition to intersection lighting, underdeck lighting would be 

provided under the bridges crossing I-10 and the UPRR. According to UPRR’s Guidelines 

for Design of Highway Separation Structures over Railroads (Overhead Grade 

Separations) dated January 1999, underdeck lighting is required for bridges that exceed 80 

feet in width. 

Proposed Bicycle and Pedestrian Facilities 

Inconsistent and discontinuous pedestrian and bicycle facilities exist within the project 

area. To promote the use of alternative modes of transportation and reduce vehicle trips, 

the existing bicycle lanes and sidewalk along Twin Peaks Road would be extended across 

the Santa Cruz River, across I-10 and the UPRR, and through the intersection of Twin 

Peaks Road/El Camino de Mañana/Linda Vista Boulevard. Along Twin Peaks Road, 

shoulders a minimum of 7 feet in width would be provided to accommodate bicycle use 



3-20 




and sidewalks would be 6 feet in width. Along the segment of Linda Vista Boulevard 

proposed for reconstruction, 6-foot wide paved shoulders could be used by bicycles, but 

sidewalks would not be provided. All sidewalks and proposed intersection improvements 

would provide crosswalks, sidewalk, and ramps that are compliant with the Americans 

with Disabilities Act (ADA) and resultant regulations. 

The proposed project would provide pedestrian and bicycle connections between the 

existing sidewalk and shared use lanes on Twin Peaks Road and the Santa Cruz River 

Shared Use Path and the Juan Bautista de Anza Historic Trail east of Continental Ranch. 

The Santa Cruz River Shared Use Path is under final design currently and will be 

completed prior to the construction of the proposed improvements to Twin Peaks Road. 

As a result, reconstruction of the path at its intersection with Twin Peaks Road would be 

required. At-grade shared use path crossings of Twin Peaks Road were not recommended 

because of potential vehicle conflicts; therefore, users of the shared use path would be 

diverted along the Twin Peaks Road embankment approximately 850 feet east of the 

shared use path’s alignment. In this location, both the Santa Cruz River Shared Use Path 

and the proposed Juan Bautista de Anza Historic Trail would cross Twin Peaks Road 

beneath the proposed Santa Cruz River Bridges. The connection to the Santa Cruz River 

Shared Use Path is illustrated in Figure 3-18. 

Figure 3-18. Proposed Twin Peaks Road Connection to Santa Cruz Shared Use Path 

To discourage pedestrian crossing of Twin Peaks Road at the former alignment of the 

Santa Cruz River Shared Use Path, the roadway’s center median would be fenced for 

approximately 100 feet in length. This would direct path users to either cross under the 

Santa Cruz River Bridge or at the nearest intersection to the west (Twin Peaks Road and 

Clover Road). 

During public information meetings on the Twin Peaks Road TI, the public expressed 

concerns regarding the safety of children attending Twin Peaks Elementary School (7995 

West Twin Peaks Road). As a result, the Town of Marana chose Twin Peaks Elementary 

School as their initial Safe Routes to School program. A successful grant application 



3-21 




would result in the construction of a 4,500-foot long, 14-foot wide shared use path along 

the south side of Twin Peaks Road from Silverbell Road to Coachline Boulevard and 

along Coachline Boulevard from Twin Peaks Road to Desert Spirits Drive 

(approximately 725 feet south of Twin Peaks Road). Although the Twin Peaks Road TI 

project does not provide funding for this shared use path, the social, economic, and 

environmental effects of this path are addressed within this document to increase the 

probability of the grant application’s success. 

Proposed Drainage Improvements 

Drainage issues in the study area were documented in the Interstate 10 Traffic 

Interchange at Twin Peaks/Linda Vista Final Drainage Report, dated May 21, 2004. 

Although readers are referred to the Final Drainage Report for a more thorough 

discussion, the results of the analyses are summarized here. 

Roadway Drainage 

Pavement drainage from Twin Peaks Road is collected currently by curb and gutter and 

transmitted to storm drains along the outsides of the roadway. Catch basins and storm 

drain pipe collect the drainage and transmit the water to drainage channels, which drain 

to tributaries of the Santa Cruz River. The western portion of Linda Vista Boulevard 

(near its intersection with El Camino de Mañana) and El Camino de Mañana have no 

curb and gutter and pavement drainage sheetflows off the roadway into small roadside 

ditches adjacent to the roadway. 

Proposed improvements to Twin Peaks Road would use curb and gutter to collect 

pavement drainage. Catch basins and storm drain pipe would collect the runoff and 

transmit the water to the nearest cross drainage channels, which would drain eventually to 

the Santa Cruz River. Where curbs are proposed for Linda Vista Boulevard and El 

Camino de Mañana (near the El Camino De Mañana/Linda Vista Boulevard intersection 

only) the method of drainage would be the same as that described for Twin Peaks Road. 

Beyond the reaches of the intersection, runoff would flow off the roadway into roadside 

ditches and to the nearest cross drainage facility. 

Due to the absence of curb and gutter, pavement drainage on the frontage roads is 

currently collected in roadside ditches and conveyed to existing cross culverts. Under 

proposed conditions, curb and gutter would be installed along portions of the frontage 

roads and a catch basin/storm drain system would be used to collect flows and convey 

them to the nearest cross drainage facility. In addition, median drainage would also be 

intercepted by the storm drain system for conveyance to the nearest cross drainage 

facility. 

Cross Culvert Design 

Drainage facilities under I-10 and the frontage roads were developed assuming the 50year 

storm event in accordance with ADOT design criteria. The design considered 

existing box capacities and outfall angles in relation to receiving channels. In general, 

where existing facilities are proposed to be augmented, the existing culvert sizes were 

duplicated for the new culvert cell. Where feasible, larger cells were proposed to increase 

capacity and decrease the number of additional cells required for augmentation. The 



3-22 




proposed culvert locations and sizes under I-10 are compared with the existing structures 

in Table 3-1. The structure locations are illustrated in Figure 3-19. 

Table 3-1. Existing and Proposed I-10 and Frontage Road Drainage Structures 

Location 

(approximate 


Milepost) 

244.48 

Type of 

Improvement 

Augmentation 

/ Extension 

244.81 Extension 

Existing Size 

and Structure 

Under 

Frontage Road 

2 - 6-foot by 3foot 

cells 

RCBC 

2- 8-foot by 

3.5-foot cells 

RCBC 

Existing Size 

and Structure 

Under I-10 

mainline 


cells 

RCBC 

2- 8-foot by 


RCBC 

244.94 New Structure New - N/A New - N/A 

245.16 Replacement 

245.38 Replacement 

245.87 

Augmentation 

/ Extension 


cells 

RCBC 

3 - 5-foot by 


RCBC 

2 - 6-foot by 


RCBC 


cells 

RCBC 


cells 

RCBC 


cells 

RCBC 

Proposed Size and 

Structures for 

both I-10 

mainline and 

Frontage Road 

7 - 8-foot by 3-foot 

cells RCBC 

No change – 

extend RCBC only 

6 – 10-foot by 4foot 

cells RCBC 

3 – 10-foot by 4foot 

cells RCBC 

4 - 8-foot by 4-foot 

cells RCBC 


cells RCBC 

Cross drainage stormwater would be transmitted under Twin Peaks Road and Linda Vista 

Boulevard by a combination of reinforced concrete pipes (RCP) and reinforced concrete 

box culverts (RCBC). The sizes of these structures were developed assuming the 100year 

storm event in accordance with Pima County design criteria, because these drainage 

facilities are located outside ADOT right-of-way. The proposed culvert locations and 

sizes under Twin Peaks Road and Linda Vista Boulevard are shown in Table 3-2. The 

structure locations are illustrated in Figure 3-19. 

Table 3-2. Proposed Twin Peaks Road and Linda Vista Boulevard Drainage Structures 

Location (Distance and Direction from Twin 

Peaks Road/El Camino de Mañana/Linda Vista 

Boulevard Intersection) 



Proposed Structure and Size 

535 feet west 2 - 6-foot by 4-foot cells RCBC 

400 feet east 1 – 8-foot by 4-foot cell RCBC 

1,038 feet east 1 – 48-inch RCP 

1,660 feet east 2 - 6-foot by 4-foot cells RCBC 

2,595 feet east 2 - 36-inch RCP 

3-23 




Channel Design 

After stormwater runoff is carried under the roadways in culverts or pipes, it would be 

transmitted to the Santa Cruz River in open channels. Because the existing outfall 

channels downstream of the I-10 mainline and eastbound frontage road are located 

outside ADOT right-of-way, they were designed in accordance with Pima County 

requirements to convey the 100-year rainfall event. These channels discharge into the 

Santa Cruz River through openings in the soil cement bank protection. 

The existing channels are undersized to convey 100-year rainfall events. As a result, the 

channels near I-10 would be either enlarged or replaced with larger structures. The 

location, structure, and size of these proposed improvements to drainage channels are 

compared to existing channels in Table 3-3. All proposed channels were designed to 

provide one foot of freeboard. The channel locations are illustrated in Figure 3-19. The 

proposed channel improvements would require widening existing discharge locations into 

the Santa Cruz River in two locations (the channel outfalls at approximate I-10 MPs 

require widening also. Flows would be slowed by grade control structures or similar 

means prior to discharging into the Santa Cruz River; therefore, energy dissipation 

structures within the Santa Cruz River channel would not be required. 



Figure 3-19. Proposed Drainage Facilities Near I-10 

3-24 




Near the proposed intersection of Twin Peaks Road/El Camino de Mañana/Linda Vista 

proposed alignment of Twin Peaks Road in this area would interfere with historic 

drainage patterns. Water that currently flows south across El Camino de Mañana would 

be blocked by the proposed roadway; therefore, a channel is proposed to convey this 

blocked flow southwesterly along the north side of Twin Peaks Road (see Figure 3-19). 

These flows would be combined with the discharge from the proposed 2-cell 6-foot by 4foot 

RCBC under Twin Peaks Road. The proposed channel will be lined, have a base 

width of 5 feet, and provide for a depth of flow between 1.91 and 2.65 feet. Flows from 

this channel would continue southwest to the new channel that would discharge into the 

cross drainage structure at approximate I-10 MP 244.81. Routing the flows in this manner 

would avoid two drainage structures under Twin Peaks Road. 

Table 3-3. Existing and Proposed Channels Serving I-10 and Frontage Roads 

Outfall Location 

(approximate I-10 

Milepost) 



Existing Channel Bottom 

Width and Depth (approx.) 

3-25 

Proposed Channel Bottom 

Width and Flow Depth 

244.41 20 feet wide by 3.5 feet deep 70 feet wide by 3.38 feet deep 

244.80 7 feet wide by 4 feet deep 30 feet wide by 2.74 feet deep 

244.81 New – N/A 50 feet wide by 2.92 feet deep 

245.18 6 feet wide by 3 feet deep 40 feet wide by 3.05 feet deep 

245.19 3 feet wide by 3.5 feet deep 40 feet wide by 3.1 feet deep 

Proposed Santa Cruz River Channel Modifications 

Twin Peaks Road would approach the Santa Cruz River on both sides on embankment 

and then cross the Santa Cruz River on twin bridge structures of approximately 750 feet 

in length. The roadway and bridge embankments would place a large volume of fill 

within the Santa Cruz River floodplain. The fill would displace an equal volume of water 

and, if no additional action were taken, would change the 100-year floodplain elevation. 

To prevent any increase in flood water elevation, the low flow channel of the Santa Cruz 

River would be widened to offset the volume displaced by the roadway and bridge 

embankment. This topic will be discuss in greater detail in the Chapter 4, Affected 

Environment in the Section entitled Floodplains (see page 4-14). 

The following chapter discusses the existing project area environment and anticipated 

effects to social, economic, and environmental resources within the project area from the 

construction of the preferred alternative. These effects are compared with the effects that 

would result from the no build alternative (doing nothing). 



Affected Environment and Environmental Impacts October 2005 

CHAPTER 4: AFFECTED ENVIRONMENT AND 

Land Use 

Existing Conditions 

ENVIRONMENTAL IMPACTS 

Within the study area, several different governmental entities have jurisdiction, 

including the Town of Marana, Pima County, ADOT, and FHWA. Most of the 

project area is within the incorporated area of the Town of Marana, but the 

commercial area on the west side of I-10 near the Twin Peaks Road TI is within 

unincorporated Pima County. Twin Peaks Road and portions of El Camino de 

Mañana and Linda Vista Boulevard are under the shared control of the Town of 

Marana and Pima County and are maintained through memoranda of 

understanding between the two entities. The boundaries of the jurisdictions are 

illustrated on Figure 4-1. 

Land ownership is diverse in the study area also. In the western part of the study 

area (Continental Ranch), the land is almost entirely privately owned. An 

exception to private ownership in this area is the Twin Peaks Elementary School 

which belongs to the Marana Unified School District. The area within the high 

flow channel of the Santa Cruz River is under the control of Pima County. Near 

the Twin Peaks Road TI, west of I-10, the property ownership is varied, consisting 

primarily of privately owned parcels, but parcels belonging to Pima County, the 

City of Tucson, and the Cortaro-Marana Irrigation District (CMID) are present 

also. I-10 is a federal facility under the joint control of FHWA and ADOT. A canal 

owned by CMID lies between I-10 and the westbound frontage road and the 

railroad line owned by the UPRR lies east of the westbound frontage road. The 

towers that support the TEP transmission lines are located within utility easements 

east of the railroad. With the exception of these linear facilities, the study area east 

of I-10 is almost entirely privately owned. The notable exceptions are Arthur Pack 

Regional Park and Mountain View High School in the extreme eastern part of the 

study area, which are owned by Pima County and the Marana Unified School 

District, respectively. 

The proposed improvements would occur in areas under the auspices of both the 

Town of Marana and unincorporated Pima County. The land use policies of both 

entities are represented in their respective general plans. Actual land uses, 

however, do not follow necessarily the adopted land use patterns of general plans 

because many current land uses were in existence prior to adoption of the general 

plans. 



4-1 



Avra 

Valley Rd. 

Twin Peaks Rd. 

Silverbell Rd. 

Town of Marana Pima County 




I10 

Linda Vista Blvd. 

Cortaro Rd. 

4-2 

Hartman Ln. 

Camino de Oeste 

Thornydale Rd. 

Figure 4-1 

Land Jurisdiction 




The study area is a mix of land uses. The study area contains vacant, residential, 

commercial, public and institutional, and parks and open space land uses. The land 

uses planned within the study area exhibit a major loss of vacant land. Vacant land 

is replaced primarily by low density residential and master planned developments, 

corridor commerce, and conservation/mitigation land uses. 

Impacts 


The no build alternative would not affect the existing rights-of-way or easements, 

or result in land acquisitions within the project area. 


The preferred alternative would acquire additional right-of-way (R/W) for 

roadway improvements and construction of the Twin Peaks Road TI and would 

acquire additional drainage easements. The proposed improvements would be in 

accordance with the Town of Marana and Pima County general plans. 

The preferred alternative would acquire a total of 72.4 acres of private and state or 

federal property for needed R/W. The proposed acquisitions are presented by 

proposed use of the property, number of acres by ownership type, and number of 

parcels affected in the following table. 

Proposed Use 

Extension of Twin Peaks 

Road 

Reconstruction of eastbound 

I-10 frontage road 

Table 4-1. Proposed Property Acquisitions 

State or 

Federal 

Property 

(acres) 

Number of 

Affected State 

or Federal 

Parcels 

Private 

Property 

(acres) 

Number of 

Affected 

Private 

Parcels 

15.7 6 28.1 12 

0.7 1 12.1 6 

Proposed access road 5.8 6 10.0 5 

In addition to the R/W for roadways, a number of new drainage easements would 

be required for the preferred alternative. These supplemental drainage easements 

would total 8.5 acres, and are detailed below. The channels and drainage structures 

are illustrated in Figure 3-19 in Chapter 3, Alternatives. 

Partial parcel acquisition could result in unusable or undesirable parcel sizes. For 

example, parcels could be created that may not meet minimum regulatory lot size 

requirements for septic tanks and/or private wells or may result in parcels that 

become undesirable for current uses. During individual property R/W negotiations, 

the effects of partial property takes would be considered. 



4-3 




Approximate 

Location (MP) 

Mitigation 

Table 4-2. Proposed Additional Drainage Easements 

Existing 

Easement 

Width (feet) 

Proposed 

Easement 

Width (feet) 

Additional 

Easement 

Needed (acres) 

244.48 50 150 1.2 

244.81 25 75 1.0 

244.94 None 120 1.6 

245.16 None 100 2.4 

245.38 50 120 2.3 

The Town of Marana would conduct all acquisitions and relocations in accordance 

with the Uniform Relocation Assistance and Real Property Acquisition Policies 

Act of 1970, as amended. Sections 28-1841 through 28-1853 of Arizona Revised 

Statutes would be followed to provide for implementation of the Federal 

Relocation Assistance Program on a state level. During individual property rightof-way 

negotiations, the Town of Marana would consider the effects of partial 

property takes. During individual property right-of-way negotiations, the Town of 

Marana would address businesses access across other parcels to reach the access 

roadway. 

Conclusion 

The preferred alternative would be consistent with the transportation and land use 

elements of the Town of Marana and Pima County general plans and would assist 

in attaining these elements of the plans. Although property would be acquired to 

construct the proposed improvements, the impacts associated with these 

acquisitions would be minimized by following the Uniform Relocation Assistance 

and Real Property Acquisition Policies Act of 1970, as amended, and Sections 28- 

1841 through 28-1853 of Arizona Revised Statutes. 

Land Resources 

The following sections discuss conditions pertaining to land resources found 

within the study area. Components of land resources include topography, soils, 

mineral resources, and agriculture. 

Topography 


Elevations in the study area range from approximately 2,100 feet above sea level 

(a.s.l.) along the Santa Cruz River to over 2,500 feet at Rillito Peak on the west 

side of I-10 and south of Avra Valley Road. In general, the topography of the 

study area is relatively flat along the Santa Cruz River, with gently sloping terrain 



4-4 




to the east and west of the Santa Cruz River. Slopes angle toward the Santa Cruz 

River. Slopes increase in the eastern portion of the study area near the foothills of 

the Santa Catalina Mountains and Tortolita Mountains. The Santa Cruz River and 

floodplain is the dominant topographic feature in the project area. With the 

exception of the Santa Cruz River, there are no unique or important topographic 

features in the study area. 

Impacts 


The no build alternative would have no impact on topography in the project area. 


Although the preferred alternative would construct an elevated roadway and 

bridges over the Santa Cruz River, I-10, and the UPRR, existing slopes and other 

topographic features in the project area, would not be affected. The low flow 

channel of the Santa Cruz River would be widened to compensate for the roadway 

and bridge embankment fill placed within the high flow Santa Cruz River channel 

(see Floodplain Section, page 4-14); however, these impacts would not affect the 

Santa Cruz River flows or functions. 

Mitigation 

As described in the previous paragraph, no mitigation measures for topography are 

necessary, if the preferred alternative were constructed. 

Soils 


Soil types were identified for the study area through a review of comprehensive 

maps compiled by the United States Department of Agriculture, Natural Resources 

Conservation Service (NRCS) compiled in 2003, and the Arizona Agricultural 

Experiment Station in 1969. As would be expected in a fluvial depositional 

system, soils vary widely throughout the study area, often changing over distances 

of tens of feet. Soils are predominantly of the Anthony, Agua and Grabe Series. 

Anthony series consists of well-drained sandy loams to gravelly sandy loams. 

These soils are formed in mixed material that was deposited on flood plains and 

alluvial fans by rivers and streams. Slopes are 0 to 5 percent. Permeability of these 

soils is moderately rapid and the hazard of erosion is moderate. These soils are 

found throughout the study area. 

Agua Series soils consist of well-drained fine sandy loams about 2 feet thick over 

fine sand. These soils formed in mixed material that was deposited on flood plains 

by rivers and streams. Deposits of the Aqua series are found on the flood plain of 

the Santa Cruz River. Slopes are generally level and runoff is slow. Hence, the 

hazard of erosion is slight to moderate. 



4-5 




Grabe series soils consist of well-drained loams, gravelly loams, and silty clay 

loams. These soils form in recent alluvium deposited in flood plains, alluvial fans, 

and valley slopes. Slopes range from zero to three percent. Permeability of these 

soils is rapid and the hazard of erosion is slight. Grabe gravelly sandy loams are 

generally found in the alluvial fans of the Santa Cruz River Valley. 

Impacts 


The no build alternative would have no effects on soils in the project area. 


During construction, disturbed soils in the project area would be vulnerable to 

erosion. This is especially true for soils that are highly susceptible to erosion by 

water or wind. According to the soil survey, soils present in the project area have a 

slight to moderate hazard of erosion. Prior to construction, a Storm Water 

Pollution Prevention Plan (SWPPP) and Dust Control Plan would be developed 

and implemented. Management practices contained in these plans would minimize 

soil erosion from stormwater runoff and wind as a result of the preferred action. 

Mitigation 

The SWPPP, which is discussed in detail in the National Pollutant Discharge 

Elimination System (NPDES)/Arizona Pollution Discharge Elimination System 

(AZPDES) Section entitled NPDES/AZPDES/SWPPP (page 4-21), would outline 

the implementation sequence of erosion and sediment control measures. These 

may include stabilization practices, structural controls, storm water management 

measures, and best management practices to mitigate the water erosion of soils. In 

addition, an activity permit from the Pima County Department of Environmental 

Quality and a grading permit from the Town of Marana would be obtained to limit 

the amount of dust generated from construction activities (see Air Quality Section, 

page 4-45). 

Geologic Setting and Mineral Resources 


Regional Geology 

The project site is located within the Tucson basin, which is a sub-area of the 

Upper Santa Cruz River drainage basin (Davidson 1973, Anderson 1987). The 

Tucson basin is a structural depression within the Basin and Range physiographic 

province. The basin is filled with sediments and generally trends north to 

northwest. The Town of Marana, and this project, is located in the northwestern 

part of the basin. 

The primary formations of interest for this project are, in descending order, the 

Fort Lowell Formation and the Upper Tinaja Beds. Both the Fort Lowell 

Formation and the Tinaja beds were developed as a result of sedimentation in a 



4-6 




closed basin of internal drainage. The Fort Lowell Formation, which is generally 

300 to 400 feet thick, grades from silty gravel near the edges of the basin to silty 

sand and clayey silt in the central part of the basin. In most of the basin, the Fort 

Lowell Formation was deposited in fans by streams that spread out from the 

canyons in the surrounding mountains. The Tinaja beds, which vary from less than 

one foot to more than 2,000 feet thick and have up to three subunits, consist of 

gravel and sand (upper bed) that grade into a very thick sequence of gypsiferous 

clayey silt and mudstone in the center of the basin (lower bed). The Fort Lowell 

formation is early and middle Pleistocene in age, while the Tinaja beds range in 

age from Miocene to Pliocene. Tilting, accompanied by minor faulting, ended the 

sedimentation of the Fort Lowell Formation and initiated erosion and the early 

stages of the present drainage system, including the deposition of young 

Quaternary alluvium along the Santa Cruz River. 

Localized Surficial Geology 

Since the project site is located within or close to the range of influence of the 

meander migration of the Santa Cruz River, it can be expected that the near surface 

soil deposits would exhibit gradational characteristics ranging from fluvialdeposited 

silty and clayey soils to sandy and gravelly deposits. Below these 

surficial deposits, dense layers of sand and gravel of the Fort Lowell Formation 

with varying quantities of silt and clay would be encountered. The base of the Fort 

Lowell Formation is expected to be at approximately 2,000 feet, or approximately 

130 feet below existing grade, and so the very dense Upper Tinaja unit is unlikely 

to be encountered on this project. 

Seismic Conditions 

Based on ADOT seismic acceleration maps (Euge, Kenneth, and Schell 1992) and 

AASHTO Standard Specifications for Highway Bridges, seismic loading is not 

incorporated in the design of the bridges. Furthermore, there are no special seismic 

design requirements for the foundations and abutments of bridges in this category. 

Mineral Resources 

Sand and gravel mining operations have operated and continue to operate within 

the study area. An existing sand and gravel mining operation (I-10 Avra Valley 

Mining and Development) is located on the west side of the Santa Cruz River 

south of Avra Valley Road, which is north of the project area. Although no longer 

a mining operation, a former sand and gravel mine was located in the northern 

portion of the project area between the Santa Cruz River and I-10. This area is now 

used for industrial operations. An active sand and gravel mining operation (Rinker 

Materials) is located in the southern project area immediately south of the south 

access road. In addition to sand and gravel mining, Arizona Block and Brick, in 

the southern portion of the project area mines and processes raw material on-site 

into adobe block. 



4-7 




Impacts 


The no build alternative would not effect the geological setting or mineral 

resources in the project area. 


The preferred alternative would have no effect on the geological setting or mineral 

resources in the project area. Although the study area contains former and existing 

sand and gravel mining and abode mining and manufacturing, the proposed 

improvements would not impact any existing mining operations. There are no 

special seismic design requirements for the foundations and abutments of proposed 

bridges in the project area. 

Mitigation 

No mitigation measures are necessary because the preferred alternative would 

have no effect on the geological setting or mineral resources in the project area. 

Agriculture 


Two large areas west of I-10 and east of Silverbell Road were identified as prime 

irrigated farmland in the most recent Important Farmlands map published by the 

NRCS. Since the NRCS last surveyed for prime farmlands in 1982, the land 

designated as prime irrigated farmland has been developed for commercial or 

residential uses. One of these areas was located west of the Santa Cruz River and 

is now occupied by Continental Ranch, a large master-planned community. No 

farming occurs in this area. The other area was located between the Santa Cruz 

River and I-10 and stretched from Cortaro Road north to the southern part of the 

project area. This area is currently occupied by the Pines Golf Club at Marana and 

is not farmed. As a result of development in the area, no prime farmland exists in 

the study area. 

Impacts 


Because no prime, unique, or farmland of state or local importance exists within 

the project area, the no build alternative would have no effects on agricultural land. 


Because no prime, unique, or farmland of state or local importance exists within 

the project area, the preferred alternative would have no effects on agricultural 

land. 



4-8 




Mitigation 

No mitigation measures are required because the preferred alternative would have 

no effects on agricultural land. 

Conclusion 

The preferred action would not alter or impact slopes or substantially effect 

important topographic features in the project area. Although disturbed soils in the 

project area would be vulnerable to water and wind erosion, the SWPPP and air 

quality permitting regulations followed for this project would result in no impacts 

to area soils. The preferred alternative would have no effects on the geological 

setting or mineral resources in the project area and no prime, unique, or farmland 

of state or local importance exists within the project area; therefore, the preferred 

alternative would have no effects on agricultural land. 

Water Resources 

The following sections discuss surface water and groundwater conditions within 

the study area. Surface water resource concerns include potential impacts to rivers 

and intermittent washes. The Santa Cruz River and numerous washes that drain 

into the Santa Cruz River are the dominant surface water features in the study area. 

Groundwater is defined as stored water beneath the ground surface that can be 

used to supply wells and springs. This water is stored in natural underground 

reservoirs composed of loose rock fragments called aquifers. 

Surface Water 


The main surface water drainage in the study area is the Santa Cruz River, which 

runs approximately parallel to and west of I-10 within the study area. The Santa 

Cruz River originates in the San Rafael Valley in Arizona, and then flows south 

into Mexico before bending west and north and reentering the United States east of 

Nogales, Arizona. Near the study area, a perennial nine-mile reach of the Santa 

Cruz River flows north consisting of treated effluent discharged into the channel 

by the Ina Road and Roger Road Wastewater Treatment Plants. According to the 

Arizona Department of Environmental Quality (ADEQ), the portion of the Santa 

Cruz River that flows through the study area is classified as Effluent Dominated 

Waters. Swimming and fishing are deemed not allowable uses for the Santa Cruz 

River, but it is suitable for bird-watching and other terrestrial activities. With the 

exception of this effluent dominated reach, the remainder of the Santa Cruz River 

within the study area is intermittent and flows in response to rainfall events. 

The Canada del Oro Wash and many minor unnamed washes drain into the Santa 

Cruz River within the study area. All of these washes are ephemeral, flowing only 

in response to rainfall events. According to the Drainage Report prepared for this 

study, the Canada del Oro Wash and several minor unnamed washes originate in 



4-9 




of the Santa Catalina Mountains while other minor washes originate in the 

Tortolita Mountains located to the northeast of the study area. According to the 

Drainage Report, runoff from Tortolita Mountains to the Santa Cruz River is 

impeded by the UPRR, the I-10 westbound frontage road, and the I-10 mainline. 

The UPRR is located on the upstream side of the westbound frontage road, and, 

because the existing cross drainage structures are undersized, this causes flow 

from the upstream watersheds to pond at the drainage structures. Excess flows not 

conveyed by cross drainage structures continue to the northwest along the 

upstream side of the UPRR to the next cross drainage structure. This pattern is 

consistent throughout the study area, and continues beyond the limits of the study 

area. 

Additional cross drainage structures are located under the I-10 frontage roads and 

mainline. Generally there is adequate drainage capacity to prevent the 50-year 

rainfall event from ponding on the I-10 frontage roads and mainline because of a 

combination of: 1) the metering of flows to the roadways by the UPRR drainage 

structures; 2) the capacities of the I-10 frontage road and I-10 mainline drainage 

structures; and 3) the capacities of the roadside ditches which transmit flows along 

the roadways to the northwest. In one area north of the Twin Peaks Road TI and 

one location south of the Twin Peaks Road TI, however, runoff exceeds the 

capacity of this system. In these locations, water can flow over the westbound 

frontage road and the I-10 mainline during a heavy rainfall event. 

There are no cross drainage structures along El Camino de Mañana and Linda 

Vista Boulevard within the study area and stormwater runoff currently overtops 

the surface of these roadways. 

Impacts 


Under the no build alternative, no impacts to surface water resources would result 

and no improvements to the drainage facilities near I-10 would occur; however, 

drainage improvements would occur as a part of the ultimate freeway 

improvements proposed in the I-10 General Plan. According to PAG’s 2025 

Regional Transportation Plan (as amended), I-10 is proposed to consist of 8 lanes 

by 2025 from the Pinal/Pima County line to the I-10/I-19 Interchange. However, 

these improvements are not programmed (planned and funded) in PAG’s 2005- 

2009 Transportation Improvement Program; therefore, it may be assumed that 

these improvements would be programmed between the years 2010 and 2025. As a 

result, the potential for a heavy rainfall event to cause water to flow over the 

westbound frontage road and the I-10 mainline in the project area would remain 

until these improvements were completed. 

Under the no build alternative, stormwater runoff that currently flows over the 

surface of El Camino de Mañana and Linda Vista Boulevard would not be routed 

under the roadways. As a result, surface flows that may damage the structure of 

the roadways and pose a safety challenge to motorists would continue. 








The preferred alternative would widen the low flow channel of the Santa Cruz 

River to compensate for the roadway and bridge embankment fill placed within the 

high flow Santa Cruz River channel (see Floodplain Section, page 4-14). 

Widening of the low flow channel would temporarily divert surface water flow in 

the Santa Cruz River. The only surface flow diversion within the construction area 

would consist of temporary diversion structures, consisting of pilot channels and 

coffer dams, to divert water around construction areas. Normal downstream flows 

would be maintained within the capacity of the existing channel with no 

substantial alteration to flows. 

The bridges would be designed such that piers and abutments would not be placed 

within the low flow channel of the Santa Cruz River. Water would be not removed 

from the Santa Cruz River for construction of the proposed improvements. Instead 

potable water from approved sources would be used for dust suppression and other 

construction water requirements. 

Proposed improvements to Twin Peaks Road would use curb and gutter to collect 

stormwater runoff into storm drains along the outsides of the roadway. Catch 

basins would collect the runoff and transmit the water to the nearest cross drainage 

channels, which would drain eventually to the Santa Cruz River. Where curbs are 

proposed for Linda Vista Boulevard and El Camino de Mañana (near the El 

Camino De Mañana/Linda Vista Boulevard intersection only) the method of 

drainage would be the same as that described for Twin Peaks Road. Beyond the 

reaches of the intersection, runoff would flow off the roadway into roadside 

ditches and to the nearest cross drainage facility. This system would protect the 

roadway structure and remove runoff from the paths of vehicles. 

The proposed improvements to drainage facilities were described in the previous 

chapter, Alternatives, but would consist of: 

• Under I-10 and the frontage roads – Constructing one new drainage 

structure, extending one existing structure, replacing two drainage 

structures with higher capacity structures, and increasing the capacity at an 

additional 2 structures is proposed. 

• Under Twin Peaks Road and Linda Vista Boulevard – Constructing five 

new drainage structures is proposed. 

• Channels near I-10 – Constructing one new and four higher capacity open 

concrete-lined channels outside ADOT R/W is proposed. Channel flows 

would be slowed by check dams or similar means prior to discharging into 

the Santa Cruz River; therefore, energy dissipation structures within the 

Santa Cruz River channel are not proposed. 

• Santa Cruz River discharge locations for Channels near I-10 – Widening 

of the existing discharge locations into the Santa Cruz River in two 



4-11 




locations is proposed; therefore, widening the openings in the soil cement 

bank protection is proposed also. 

• Channels along Twin Peaks Road and Linda Vista Boulevard east of I-10 – 

Constructing a new channel along the north side of Twin Peaks Road is 

proposed. 

The proposed drainage improvements would provide higher capacity drainage 

structures under I-10 and its frontage roads and new facilities under Twin Peaks 

Road and Linda Vista Boulevard. As a result, the stormwater predicted to flow 

over I-10 and the westbound frontage road during high rainfall events would be 

routed under the roadways. 

The stormwater runoff that currently flows over the surface of El Camino de 

Mañana and Linda Vista Boulevard would be routed under the roadways in pipes 

and culverts. This system would protect the roadway structure and remove runoff 

from the paths of vehicles. 

The proposed improvements would improve overall drainage patterns; therefore, 

land uses near the project area would benefit from the additional capacity of the 

drainage structures. 

Mitigation 

The preferred alternative would improve drainage in the project area and would 

alter existing surface water drainage patterns into the Santa Cruz River. To prevent 

materials from entering the Santa Cruz River and its tributaries during 

construction, the contractor shall take precautions to prevent construction materials 

from being introduced into washes in accordance with Arizona Department of 


Section 104.09 (2000 Edition) and the Water Quality Standards in Title 18, 

Chapter 11 of the Arizona Administrative Code as administered by ADEQ. 

Excess waste material and construction debris would be disposed of at sites 

supplied by the contractor in accordance with Arizona Department of 


Section 107.11 Protection and Restoration of Property and Landscape (2000 

Edition). Disposal shall be made at either municipal landfills approved under Title 

D of the Resource Conservation and Recovery Act (RCRA), construction debris 

landfills approved under Article 3 of the Arizona Revised Statutes 49-241 (Aquifer 

Protection Permit) administered by the ADEQ, or inert landfills. 

Conclusion 

The preferred alternative would widen the low flow channel of the Santa Cruz 

River to compensate for the roadway and bridge embankment fill placed within the 

high flow Santa Cruz River channel. The proposed drainage improvements would 

provide higher capacity drainage structures under I-10 and its frontage roads and 

new facilities under Twin Peaks Road and Linda Vista Boulevard. As a result, the 

stormwater predicted to flow over I-10, the westbound frontage road, El Camino 



4-12 




de Mañana, and Linda Vista Boulevard during high rainfall events would be routed 

under the roadways; therefore, land uses near the project area would benefit from 

the additional capacity of the drainage structures and runoff would be removed 

from the paths of vehicles. 

Ground Water 


The aquifer underlying the Tucson metropolitan area is designated as the Tucson 

Active Management Area (AMA). This is a designation given to aquifers in areas 

where groundwater pumping is most severe (primarily urban and agricultural 

areas). Because these areas are most susceptible to depletion of water resources, 

they are carefully managed by the Arizona Department of Water Resources 

(ADWR) to ensure water supply resources for future use. Water levels continue to 

decrease in the Tucson AMA; however, these decreases have been mitigated by 

the use of Colorado River water to recharge the aquifers underlying the basin. 

Depths to groundwater in the Tucson AMA vary substantially depending on land 

surface elevations and proximity to natural drainage areas. According to the 

Preliminary Initial Site Assessment (PISA) prepared for this project, groundwater 

elevations in the study area are relatively shallow, typically less than 100 feet 

below ground surface. Groundwater conditions in the study area are affected by 

intermittent, but occasionally large, surface water flows in the Santa Cruz River. 

Surface water flows recharge the groundwater system in the vicinity of the Santa 

Cruz River as water infiltrates through the Santa Cruz River channel sediments to 

the underlying aquifer. Santa Cruz River channel recharge in the Upper Santa Cruz 

Valley Sub-basin is estimated at 31,000 acre-feet per year. Infiltration of treated 

effluent discharged to the Santa Cruz River from Pima County's regional 

wastewater treatment plants is not a component of this natural recharge estimate. 

Impacts 


Under the no build alternative, no impacts to ground water would occur. 


Groundwater would not be encountered for the majority of proposed roadway 

construction activities. Roadway construction efforts would require relatively 

shallow ground surface disturbance on higher elevations and, therefore, would not 

encounter groundwater. 

Construction activities likely to encounter groundwater are those involving the 

construction of the new twin bridges over the Santa Cruz River. For construction 

of the bridges, groundwater would be encountered, especially during the 

preparation for and placement of bridge piers and abutments. 



4-13 




Depending upon the results of the geotechnical investigations, three methods of 

drilling the piers and abutment foundations may be used. In order of preference, 

these are: 

• Dry drilling with limited isolated support - The dry method would be used 

if soils are not susceptible to cave-in. This method involves drilling to the 

desired depth and, if required, reinforcing steel is lowered into the hole and 

the hole is filled with concrete. 

• Slurry drilling - The slurry method would be used if soils are susceptible to 

cave-in or slough into the drilled hole. In this method, a slurry, produced 

by mixing bentonite or a polymer mixture with potable water, is injected 

into the drill hole, where it forms a lining on the walls of the excavation. 

The hydrostatic fluid pressure against the soil prevents caving. 

• Drilling within a casing – The casing method would be used if soils cannot 

be stabilized by slurry. A cylindrical steel casing is installed in layers 

where support is required. 

Mitigation 

To protect groundwater resources, Best Management Practices (BMP) would be 

used during construction of the bridges. These BMPs are described in detail in the 

Sole Source Aquifer Section (page 4-22). Any discharges to groundwater would be 

in accordance with state and federal regulations. To limit the amount of 

groundwater encountered, construction activities would avoid high groundwater 

flow periods during the mid to late summer. 

Conclusion 

As a result of the limited involvement of groundwater and of the proposed 

precautionary practices as outlined above, this project would not effect the quality 

of the study area’s groundwater. 

Water Quality 

Floodplains 

Floodplains are low-lying areas bordering rivers and washes that are subject to 

periodic flooding from high precipitation events. Potential impacts to floodplain 

areas are required by Executive Order (EO) 11988, Protection of Floodplains, to 

be identified, studied, and assessed to minimize the risk of flood loss, minimize 

impacts of flooding, and to preserve the beneficial values of the floodplains. 

In addition to EO 11988, Title 23 of the Code of Federal Regulations (CFR), Part 

650 (23 CFR 650), establishes the policies and procedures for the location and 

hydraulic design of highway encroachments on floodplains. 23 CFR 650 

establishes the policy of the FHWA to: 1) encourage a broad and unified effort to 

prevent uneconomic, hazardous or incompatible use and development of the 



4-14 




Nation’s floodplains; 2) to avoid longitudinal encroachments, where practicable; 

3) to avoid significant encroachments, where practicable; 4) to minimize impacts 

of highway agency actions which adversely affect base floodplains; 5) to restore 

and preserve the natural and beneficial floodplain values that are adversely 

impacted by highway agency actions; 6) to avoid support of incompatible 

floodplain development; 7) to be consistent with the intent of the Standards and 

Criteria of the National Flood Insurance Program, where appropriate; and 8) to 

incorporate “A Unified National Program for Floodplain Management” of the 

Water Resources Council into FHWA procedures. 

To determine compliance with EO 11988 and 23 CFR 650, the Federal Emergency 

Management Agency (FEMA) floodplains map of the project area was obtained 

and a location hydraulic study for the proposed improvements was conducted. The 

elements of this study are contained within the Interstate 10 Traffic Interchange at 

Twin Peaks/Linda Vista Santa Cruz River at Twin Peaks Road Existing Hydraulics 

Report, dated January 14, 2004 and the Interstate 10 Traffic Interchange at Twin 

Peaks/Linda Vista Santa Cruz River at Twin Peaks Road Preliminary Bridge 

Hydraulics Report, July 8, 2004. The reports are summarized in the following 

discussion; however, readers wishing a greater level of detail are referred to the 

full reports. 


The Santa Cruz River has been modified extensively within the study area to 

reduce the threat of flooding to nearby developments. According to the 

Continental Ranch Specific Plan, from Cortaro Road north for approximately 3 

miles (downstream), the Continental Ranch area developer constructed an 

approximately 2,000-foot wide floodway, which is referred to as the high flow 

channel of the Santa Cruz River. Within this floodway, the perennial flow of the 

Santa Cruz River is maintained within a bank-protected channel of approximately 

400 feet in width, which is referred to as the low flow channel. The low flow 

channel contains the approximate flows of a 10-year rainfall event and the high 

flow channel contains the flows of the 100-year rainfall event. 

Flood Insurance Rate Maps (FIRM) have been prepared and published by FEMA 

for the Twin Peaks study area (FIRM 0419C1015K and 0419C1605K effective 

date February 8, 1999). The portion of the project area within the high flow 

channel of the Santa Cruz River is located in Zone AE. Zone AE is defined as 

areas of 100-year floodplain with base flood elevations. Within the project area, 

the base flood elevations vary from 2088 feet above sea level in the northern 

project area to 2135 feet in the southern project area. The entire project area east of 

the UPRR is located in Zone AH. Zone AH is defined as areas of 100-year 

floodplain with shallow flooding of an average depth of between one and three 

feet. Twin Peaks Road from Coachline Boulevard east to the high flow channel of 

the Santa Cruz River is located in Zone X, as are portions of the area from the east 

bank of the Santa Cruz River high flow channel to the eastbound I-10 frontage 

road. Zone X is defined as areas: outside the 100-year flood plain; within the 100- 



4-15 




year floodplain with sheet flow flooding where average depths are less than 1 foot; 

in the 100-year floodplain with stream flooding where the contributing drainage is 

less than one square mile; or, protected from 100-year flood events by levees. The 

FIRMs for the study area are shown in Figure 4-2. 

Impacts 


Under the no build alternative, no affects to floodplains would occur. 


Based on the information contained in the FIRMs for the study area, the proposed 

improvements constitute actions within the limits of the base floodplain; therefore, 

compliance with EO 11988 and 23 CFR 650 must be demonstrated. These actions 

within the 100-year floodplain include construction of: twin bridges spanning the 

low flow channel of the Santa Cruz River; bridge and roadway embankments 

within the high flow Santa Cruz River channel; bridge and roadway embankments 

on the east side of I-10; a new signalized intersection at Twin Peaks Road/El 

Camino de Mañana/Linda Vista Boulevard; and, reconstruction of Linda Vista 

Boulevard. The floodplain analysis conducted for these improvements is discussed 

in the following paragraphs. 

The risks associated with the Santa Cruz River bridges described in Chapter 3, 

Alternatives, were analyzed. Based on the scour analysis, the Town of Marana 

would design the bridges’ substructures and foundations for these scour depths; 

therefore, risks to the structures would be minimized. 

Incompatible use or development within the floodplain would not be facilitated by 

the proposed project. Any developments within the area must comply with the 

Town of Marana or Pima County zoning and floodplain ordinances. The area east 

of the proposed improvements is within the Tortolita Basin as defined by Pima 

County. The County has designated this area as a critical basin, which requires that 

developments provide sufficient stormwater detention to reduce predevelopment 

peak flows. 

Several improvement alternatives were developed and their associated impacts to 

the 100-year floodplain were analyzed. Alternatives considered, but eliminated 

from further consideration, included: 1) the no build alternative; 2) bridges 

spanning the high flow channel of the Santa Cruz River; and, 3) bridges spanning 

the low flow channel of the Santa Cruz River. These alternatives were eliminated 

because they either did not address the stated purpose and need of the proposed 

improvements (no build alternative) or they would increase flood elevations over the 

allowable 0.1 foot according to ADOT and Pima County design standards (the two 

bridge alternatives). 



4-16 



Twin Peaks Rd 



4-17 


Linda Vista Blvd 

Figure 4-2 

Floodplain 




As a result, a modified design alternative was developed and analyzed. This 

modified design consisted of longer bridges with shorter embankments, and an 

accompanying widening of the low flow channel of the Santa Cruz River. The 

proposed design (the preferred alternative) consisted of proposed 750-foot long 

twin bridges over the low flow channel and a widening of the low flow channel to 

a 610-foot top width at the bridge crossing. The modeled channel widening 

transitioned back to the existing 400-foot width over a distance of approximately 

1,500 feet upstream and downstream of the bridge crossing. The modeled 

widening was assumed to occur entirely on the west side of the existing low flow 

channel because the existing bank protection on the west side of the channel 

exhibits undercutting and is in need of repairs. This alternative would not increase 

flood elevations by more than 0.1 foot; therefore, this alternative was advanced for 

preliminary design and environmental investigation. 

The alternatives and analyses within the floodplain were developed in consultation 

with several local, state, and federal water resource and floodplain management 

agencies. Meetings or telephone conversations with ADOT and the U.S. Army 

Corps of Engineers (Corps) were held to obtain current information on 

development and proposed actions in the affected watersheds. These discussions 

helped also guide the preliminary alternatives design. The resulting analytical 

reports were shared with the Town of Marana Floodplain Coordinator and the 

Arizona State Floodplain Coordinator; therefore, the preferred bridge alternative is 

consistent with existing watershed and floodplain management programs. 

Although removal of vegetation during construction would occur, the Town of 

Marana would minimize vegetation removal and would develop a revegetation 

plan that would improve the value of the vegetation in the disturbed area of the 

floodplain. This is discussed in the Threatened and Endangered Species Section 

(page 4-26). As a result, the quality of habitat to be used by wildlife, would be 

improved with no reduction in the ability of the floodplain to mitigate the 100-year 

flooding event. 

As discussed above, the preferred bridge alternative is the only practicable 

alternative. The project must be located within the floodplain to enhance 

transportation connectivity across the Santa Cruz River. Although other 

alternatives were considered, these alternatives were not practicable because they 

could not meet freeboard requirements or they resulted in an unacceptable increase 

in flood elevations. The preferred bridge alternative conforms to applicable State 

and local floodplain protection standards. 

Mitigation 

The preferred alternative would implement measures to minimize floodplain 

impacts to the proposed improvements and to minimize floodplain impacts caused 

by the action. Based on the bridge analysis, the substructure and foundation of the 

bridge would be designed for appropriate scour depths to minimize risks to the 

structures. Twin Peaks Road, Linda Vista Boulevard, and El Camino de Mañana 



4-18 




would be designed and constructed as all-weather roadways designed to withstand 

a 100-year flood event. 

To mitigate the impacts to the floodplain from the preferred alternative, several 

mitigative measures would be implemented. These include: 

• The Town of Marana would widen the low flow channel of the Santa Cruz 

River to prevent an unacceptable rise in floodwater elevations within the 

100-year floodplain. 

• Prior to the removal of vegetation during construction, the Town of Marana 

would develop a revegetation plan (See Biological Resources Section, page 

4-25). 

• During final design, the Town of Marana would give the local floodplain 

administrator the opportunity to review project plans. 

Section 404/401 of the Clean Water Act 

Section 404 of the Clean Water Act (CWA) establishes a permit program for 

activities that would discharge dredged or fill material into "waters of the United 

States." This permit program is authorized by the Corps. "Waters of the United 

States" is a broad term that includes: (1) waters, lakes, rivers, and streams that are 

navigable waters of the United States, including adjacent wetlands: (2) tributaries 

to navigable waters of the United States, including adjacent wetlands: and (3) other 

waters, such as isolated wetlands and intermittent streams, the degradation or 

destruction of which could affect interstate commerce. 


Jurisdictional waters of the U.S. in the study area were delineated by the Town of 

Marana for the proposed improvements and for private development projects in the 

area. These delineations were compiled and submitted to the Corps for 

concurrence. The Corps concurred with these delineations, which appear in Figure 

4-3. As presented in Figure 4-3, three major jurisdictional waters and several 

minor tributaries were delineated. Two of the waters flow through box culverts 

beneath I-10, the eastbound and westbound frontage roads, and the UPRR. The 

third water is the low flow channel of the Santa Cruz River. The total area of 

jurisdictional waters within the project area is 47.39 acres. 

Impacts 


Under the no build alternative, no affects to Waters of the U. S. would occur. 


Waters of the U.S. would be impacted by the preferred alterative. The bridge 

spanning the Santa Cruz River and the widening of the low flow channel in the 

Santa Cruz River would impact Waters of the U.S. In addition, redirection of a 



4-19 





4-20 

Figure 4-3 

Jurisdictional Waters 




wash at the intersection of Twin Peaks Road and El Camino de Mañana, and three 

wash crossing of Linda Vista Boulevard would impact Waters of the U.S. 

Coordination with the Corps indicates the preferred alternative would require an 

individual permit under Section 404 of the CWA and would require individual 

water quality certification under Section 401 of the Act from ADEQ. The terms 

and conditions of the Corps’ individual 404 Permit would be followed by the 

contractor for work affecting jurisdictional waters within the project area. 

Mitigation 

The Town of Marana would obtain an individual Clean Water Act Section 404 

permit from the U.S. Army Corps of Engineers and Section 401 Water Quality 

Certification from the Arizona Department of Environmental Quality before 

construction commences. The terms and conditions of the Clean Water Act 

Section 404 permit from the U.S. Army Corps of Engineers and Section 401 Water 

Quality Certification from the Arizona Department of Environmental Quality 

would be followed by the contractor for work affecting jurisdictional waters within 

the project area. 

NPDES/AZPDES/SWPPP 

Under Section 402(p) of the CWA, an AZPDES general permit from ADEQ is 

required for construction activities when one acre or more of land would undergo 

excavation and/or grading during construction. The main objectives of the 

permitting program are to reduce erosion, minimize sedimentation, and eliminate the 

discharge of non-storm water pollutants. All work that meets the disturbance 

conditions must be permitted. 

On August 22, 2005, the Ninth Circuit Court of Appeals vacated the United States 

Environmental Protection Agency (EPA) delegation of Clean Water Act permitting 

authority to the State of Arizona. The ruling questions the validity and status of 

permits issued and managed under the Arizona Pollution Discharge System 

(AZPDES), including the construction general permit for stormwater discharges and 

individual AZPDES permits. 


There are no storm water pollution prevention plans in place in the project area. 

Impacts 


Under the no build alternative, no land disturbance would occur and sediments 

would not be discharged. 


The preferred alternative would excavate and/or grade more than one acre of land; 

therefore, an AZPDES permit would be required. 



4-21 




Mitigation 

To comply with Section 402, a SWPPP would be prepared for this project by the 

Town of Marana. The SWPPP would incorporate temporary erosion control 

measures during construction, permanent erosion control measures when the 

project is completed, and good housekeeping practices for the control and 

prevention of release of water pollutants. The SWPPP would identify the project 

scope, anticipated acreage of land disturbance, and the pollution control measures 

that would be implemented to reduce soil erosion, while containing and 

minimizing the construction pollutants (including oils, gasoline, and other 

chemicals released by construction equipment and vehicles) that may be released 

to surface waters through runoff during a storm event. The ADOT District 

Construction Office and the contractor will submit the Notice of Intent and the 

Notice of Termination to the Arizona Department of Environmental Quality and 

the EPA. ADOT would monitor all mitigation measures encompassing 

sedimentation and erosion control measures to affirm that these measures are being 

followed correctly and are providing the appropriate protection to sensitive areas. 

During construction of the project, care shall be taken to ensure that construction 

materials are not introduced into the washes, in accordance with Arizona 

Department of Transportation’s Standard Specifications for Road and Bridge 

Construction Section 104.09 (2000 Edition) and the Water Quality Standards in 

Title 18, Chapter 11 of the Arizona Administrative Code as administered by 

ADEQ. Excess concrete, curing agents, form work, waste materials, lubricants, 

and fuel would not be disposed of within the project boundaries. In the event of 

accidental chemical spills during construction, the site would be cleaned up to 

prevent chemical introduction into the surface or groundwater systems. Incidents 

involving hazardous materials would be coordinated by ADOT's Engineer. These 

measures would protect both surface and groundwater. 

Sole Source Aquifer 


Under Section 1424(e) of the Safe Drinking Water Act, the U.S. Environmental 

Protection Agency (EPA) designated the Upper Santa Cruz and Avra Valley 

Basin, which underlies the study area, as a sole source aquifer. This designation 

means that the area has an aquifer which is the sole or principal drinking water 

source for the area and which, if contaminated, would create a significant hazard to 

public health. 

As a result of this designation, proposed federal financially-assisted projects which 

have the potential to contaminate the designated sole source aquifer are subject to 

EPA review. Under a Memorandum of Understanding between EPA and FHWA 

dated October 1984, any proposed project that is within a designated sole source 

aquifer and which is subject to analysis through an environmental assessment, is 

subject to a Section 1424(e) review by EPA. 



4-22 




To establish compliance with Section 1424(e) of the Safe Drinking Water Act, a 

letter describing the project area and scope, anticipated involvement of 

groundwater during construction, and methods to protect groundwater resources 

during construction was sent to the EPA’s Groundwater Office. 

Impacts 


Under the no build alternative, no affects to the sole source aquifer would occur. 


Groundwater is not anticipated to be encountered for the majority of proposed 

roadway construction activities. Roadway construction efforts are anticipated to 

require relatively shallow ground surface disturbance on higher elevations and, 

therefore, are not anticipated to encounter groundwater. 

Construction activities likely to encounter groundwater are those involving the 

construction of the new bridges over the Santa Cruz River. For bridge 

construction, groundwater would be encountered, especially during the preparation 

for and placement of bridge piers and abutments; however, the bridge would be 

designed such that piers and abutments would not be placed within the River’s 

perennial flow area. 

Mitigation 

As stated in the letter to EPA’s Groundwater Office, the contractor would utilize 

BMPs during bridge construction. ADOT Tucson District would monitor bridge 

construction to ensure that BMPs are utilized by the contractor. These BMPs 

include: 

• Water repellent fluids or surface treatments would not be applied below the 

water surface; 

• Lubricants, fuels, and oils would be stored and dispensed distant from the 

Santa Cruz River channel; 

• Watercourse construction activities would occur during periods of Santa 

Cruz River low flow; 

• Disturbance to stream substrates would be minimized; 

• Gravels and rip-rap would be obtained from approved sources and be 

contaminant-free; 

• Catchments, silt fencing, or concrete barriers would be used to prevent 

debris, waste, and toxic compounds from entering the Santa Cruz River 

channel; 

• Construction equipment would be inspected daily for leaks or fluid 

discharges; 



4-23 




• Maintenance yards outside the Santa Cruz River channel would be used to 

store and service construction equipment; 

• No cement dumping or equipment cleaning would occur in or near the 

watercourse; 

• Soils that are disturbed from the Santa Cruz River channel would be 

labeled and stockpiled outside the channel until construction activities are 

completed. Then the soils removed from the Santa Cruz River channel 

would be placed back into the areas from which they were removed; and, 

• Any upland soils that are removed would moved farther upland to prevent 

erosion into the Santa Cruz River. 

As a result of the limited involvement of groundwater and of the proposed 

precautionary practices as outlined above, EPA concurred, in a letter dated May 

13, 2004, that the proposed improvements would not effect the quality of the sole 

source aquifer. This concurrence letter may be found in Appendix A. 

Conclusion 

The preferred alternative’s impacts to the quality of surface and groundwater 

resources within the study area were analyzed. This analysis determined that: 

• The preferred alternative would be consistent with existing watershed and 

floodplain management programs. 

• The preferred alternative would be the only practicable alternative for 

floodplain encroachment. 

• The preferred alternative would conform to applicable State and local 

floodplain protection standards. 

• The preferred alternative would require an individual permit under Section 

404 of the CWA and would require individual water quality certification 

under Section 401 of the Act from ADEQ. Because the Section 404 permit 

and Section 401 water quality certification would be obtained by the Town 

of Marana prior to commencement of construction within waters of the 

U.S., the preferred alternative would have no negative impacts to surface 

water quality. 

• An AZPDES general permit and a SWPPP, under Section 402(p) of the 

CWA would be required. Because the SWPPP would be prepared and 

followed during construction of the proposed improvements, the preferred 

alternative would have no negative impacts to surface water quality. 

• The proposed project is in compliance with Section 1424(e) of the Safe 

Drinking Water Act. The project has been designed in such a manner as to 

not create a significant hazard to public health, interfere with public 

welfare, or cause any public water system to install additional treatment 



4-24 




facilities to meet the National Primary Drinking Water Regulations. EPA 

has concurred with this finding. 

Biological Resources 

Biological resources included in this section are general vegetation and wildlife; 

federally endangered, threatened, proposed, and candidate species; state listed 

wildlife of concern; and protected native plants. Information on biological 

resources was obtained from a literature review, communications with local, state, 

and federal resource agencies, and field surveys. 

The study area is within the Sonoran Desert at the northern margin of the Tucson 

Basin. The Sonoran Desert has a warm climate characterized by low precipitation 

and high evapotranspiration rates. Precipitation varies considerably, but the region 

is generally arid. Although average precipitation in the Tucson area is more 

abundant than in many other parts of the Sonoran Desert, the basin receives only 

about 12 inches of precipitation annually. Summer rainfall (June through August) 

accounts for between 30 to 60 percent of the annual total, while winter 

precipitation accounts for 10 to 40 percent of the annual total. 

Topographic variability in the study area results in four distinct environmental 

zones. In the valley bottom, the Santa Cruz River floodplain and adjacent terraces 

support riparian and wetland vegetation, and provide a potential water source for 

wildlife. Creosote bush and bursage along with a variety of grasses and cacti cover 

the lower bajadas. Paloverde-mixed cacti communities, rich in saguaro and other 

cacti, grow around the mountain bases. In addition, xeroriparian vegetation 

communities are present along the washes radiating out of the mountains. 

Wildlife 


The wildlife of the area is typical of similar sites in this region of the Sonoran 

Desert. The study area occurs in what is known as the ‘urban wildland interface’. 

The ‘urban wildland interface’ is the geographical area where urban landscapes are 

mixed with natural landscapes. As a result, wildlife species common to both urban 

and natural landscapes occur in this area. Representative common wildlife species 

in the study area include coyote, bobcat, javelina, desert cottontail, turkey vulture, 

Cooper’s hawk, red-tailed hawk, mourning dove, white-winged dove, great horned 

owl, Gila woodpecker, verdin, whiptail lizard, common collared lizard, and 

common kingsnake. 

Upland and riparian landscapes in the study area have the potential to provide 

movement corridors for wildlife. In particular, the Santa Cruz River connects core 

biological areas in the region of the study area including the Tortolita Mountains, 

Tucson Mountains, Waterman Mountains, and Santa Catalina Mountains. Wildlife 

species that may use the Santa Cruz River as a movement corridor include 

terrestrial species and avian species. 



4-25 




Impacts 


Under the no build alternative, no affects to wildlife would occur. 


Proposed improvements to Twin Peaks Road, Linda Vista Boulevard, and El 

Camino de Mañana would impact vegetation that may provide wildlife habitat. 

Vegetation impacts would be limited to riparian vegetation along the Santa Cruz 

River and desertscrub vegetation in upland areas along Linda Vista Boulevard and 

El Camino de Mañana. 

The preferred alternative would not impact wildlife movement along the Santa 

Cruz River. The bottom of the proposed bridge structures over the Santa Cruz 

River would be approximately 20 feet above the low flow channel of the Santa 

Cruz River, which would allow adequate clearance for wildlife movement under 

Twin Peaks Road. New or larger diameter drainage structures under Linda Vista 

Boulevard, El Camino de Mañana, and I-10 could enhance wildlife movement 

under the roadways. 

Mitigation 

Prior to removal of vegetation during construction, the Town of Marana would 

develop a revegetation plan that would comply with the Arizona Native Plant Law 

(ANPL), and Native Plant Protection Ordinances (NPPO) of the Town of Marana 

and Pima County (see Threatened/Endangered Wildlife Species page 4-26). In 

addition, the revegetation plan would include Corps’ recommendations from the 

TRDN Feasibility Study (see Mitigation in the Threatened and Endangered 

Section below). As a result of the revegetation plan, the value of the vegetation in 

the disturbed area of the project area would be improved by construction of the 

preferred alternative. 

Conclusion 


Camino de Mañana would impact vegetation that may provide wildlife habitat; 

however, as a result of the revegetation plan, the value of the vegetation in the 

project area would be improved. The preferred alternative would not impact 

wildlife movement along the Santa Cruz River and may enhance wildlife 

movement under Linda Vista Boulevard, El Camino de Mañana, and I-10 in new 

or larger diameter drainage structures. 

Threatened/Endangered Wildlife Species 

Species 

For purposes of this assessment, federally listed wildlife species include 

endangered, threatened, proposed, or candidate species as defined in the 

Endangered Species Act (ESA) of 1973, as amended (Endangered Species Act 



4-26 




1988). The list of federal wildlife species used in this report was developed from 

the federally listed, proposed, and candidate wildlife species for Pima County from 

the U.S. Fish and Wildlife Service’s (USFWS) Arizona Ecological Field Office 

website. The species list contains 16 endangered and threatened, 1 proposed 

endangered, and 2 candidate wildlife species (Table 4-3). It was determined that 

listed species or suitable habitat could be impacted by the Preferred Alternative; 

therefore, a Biological Evaluation (BE) was prepared. The findings of this BE, 

entitled Interstate 10 Traffic Interchange at Twin Peaks/Linda Vista Biological 

Evaluation, July 27, 2004 is summarized below. 

Of the 19 species described above, 13 were not evaluated further because the 

project area is either: 1) clearly outside of the known geographic or elevational 

range of the species, or, 2) does not contain habitat characteristics known to 

support the species. Of the six remaining species, one federally listed species, 

cactus ferruginous pygmy-owl (Glaucidium brasilianum cactorum), has been 

documented by Arizona Game and Fish Department (AGFD) as occurring within 

two miles of the study area. Furthermore, the study area contains suitable habitat 

for five additional federally listed species: desert pupfish (Cyprinodon 

macularius), Gila chub (Gila intermedia), Gila topminnow (Poeciliopsis 

occidentalis occidentalis), southwestern willow flycatcher (Empidonax traillii 

extimus), and yellow-billed cuckoo (Coccyzus americanus). Each of these species 

is discussed below. 

Table 4-3. Special Status Wildlife Species 

Common Name Scientific Name Status 

Bald Eagle Haliaeetus leucocephalus Threatened 

Cactus Ferruginous Pygmy-Owl Glaucidium brasilianum cactorum Endangered 

California Brown Pelican Pelecanus occidentalis californicus Endangered 

Chiricahua Leopard Frog Rana chiricahuensis Threatened 

Desert Pupfish Cyprinodon macularius Endangered 

Gila Topminnow Poeciliopsis occidentalis occidentalis Endangered 

Jaguar Panthera onca Endangered 

Lesser Long-nosed Bat Leptonycteris curasoae yerbabuenae Endangered 

Loach Minnow Tiaroga cobitis Threatened 

Masked Bobwhite Colinus virginianus Endangered 

Mexican Gray Wolf Canis lupus baileyi Endangered 

Mexican Spotted Owl Strix occidentalis lucida Threatened 

Ocelot Leopardus pardalis Endangered 

Sonoran pronghorn Antilocapra americana sonoriensis Endangered 

Southwestern Willow Flycatcher Empidonax traillii extimus Endangered 

Spikedace Meda fulgida Threatened 

Gila Chub Gila intermedia Proposed 

Endangered 

Sonoyta Mud Turtle Kinosternon sonoriense longifemorale Candidate 

Yellow-billed Cuckoo Coccyzus americanus Candidate 



4-27 




Cactus Ferruginous Pygmy-Owl 

CFPO is listed endangered with proposed critical habitat. The pygmy-owl has been 

found in river bottom woodlands, and palo verde cacti mixed scrub associations of 

the Sonoran desert. In central and southern Arizona, the pygmy-owl is currently 

found primarily in Sonoran desertscrub vegetation with some locations in riparian 

drainages and semi-desert grassland vegetation communities. CFPO nests in 

cavities, primarily in saguaro cacti, but they would also use tree cavities. 

CFPO has been documented by AGFD as occurring within two miles of the study 

area north of Linda Vista Boulevard. Westland Resources, Inc. conducted surveys 

for CFPO during the spring of 2002, 2003, and 2004. Surveys were conducted in 

the Santa Cruz River floodplain between Twin Peaks Road in the west and I-10 

eastbound frontage road in the east; along Linda Vista Boulevard from its 

intersection with El Camino de Mañana to Thornydale Road; and along El Camino 

de Mañana from I-10 to Tangerine Road. No CFPO were detected during these 

surveys. 

The USFWS has proposed designating 1.2 million acres of critical habitat for the 

endangered CFPO in southern Arizona. Approximately 15 acres of proposed 

critical habitat for the CFPO occur in the project area. 

Desert Pupfish 

The desert pupfish is listed endangered with critical habitat. Critical habitat 

includes Quitobaquito Spring and pond in Pima County, Arizona; and portions of 

San Felipe Creek, Carrizo Wash, and Fish Creek Wash in Imperial County, 

California. The desert pupfish is found in shallow water of desert springs, small 

streams, and marshes below 5,000 feet elevation. The species tolerates high 

salinities and high water temperatures. 

AGFD records indicate that no desert pupfish surveys have been conducted within 

the study area; however, no native fish species have been documented within the 

effluent dominated reaches within the study area. Desert pupfish were not 

observed during a pedestrian survey of the study area. The closest natural 

population occurs in Quitobaquito Spring and Pond in Organ Pipe Cactus National 

Monument located approximately 200 miles southwest of the study area. 

Gila Chub 

The Gila chub is listed proposed endangered with proposed critical habitat. The 

Gila chub commonly inhabit small headwater streams, cienegas and springs, or 

marshes of the Gila River basin. They utilize diverse habitat types based on the 

season and age of the fish. Adults have been collected from deep pools with 

heavily vegetated margins and undercut banks. Juveniles have been collected from 

riffles, pools and undercut banks of runs. Gila chubs have an affinity for deeper 

pools in slow velocity water and are almost always associated with cover such as 

undercut banks, root wads, and in-stream debris piles. In larger stream systems 

they utilize heavily vegetated backwaters for cover and feeding. 



4-28 




AGFD records indicate that no Gila chub surveys have been conducted within the 

study area; however, no native fish species have been documented within the 

effluent dominated reaches within the study area. Gila chub were not observed 

during a pedestrian survey of the study area. The study area is more than 40 miles 

from the nearest population of Gila chub in the Tucson Basin. Connectivity from 

the study area to these known populations is restricted because the Pantano and 

Rillito River systems no longer have perennial flows and are dry washes with the 

exception of flows during storm events. 

Gila Topminnow 

The Gila topminnow is listed as endangered without critical habitat. The basic 

habitat requirement for the Gila topminnow is water that is permanent and free 

from nonindigenous and invasive predators. Beyond that, habitat requirements of 

Gila topminnows are broad. The species historically occupied headwater springs 

and vegetated margins and backwater areas of intermittent and perennial streams 

and rivers. Topminnows can withstand water temperatures from near freezing to 

90-100 degrees Fahrenheit. Gila topminnows can live in a fairly wide range of 

water chemistry conditions, from acidic water to water with low levels of 

dissolved oxygen. Preferred habitats contain dense mats of algae and debris, 

usually along stream margins or below riffles, with sandy substrates sometimes 

covered with organic muds and debris. 

AGFD records indicate that no Gila topminnow surveys have been conducted 

within the study area; however, no native fish species have been documented 

within the effluent dominated reaches within the study area. Gila topminnows 

were not observed during a pedestrian survey of the study area. The study area is 

more than 40 miles from the nearest population of Gila topminnow in the Tucson 

Basin. These drainages are not connected to the study area by perennial water 

flows. 

Southwestern Willow Flycatcher 

The southwestern willow flycatcher is listed endangered with proposed critical 

habitat. The southwestern willow flycatcher breeds in dense riparian habitats along 

rivers, streams, or other wetlands. The vegetation can be dominated by dense 

growths of willows, seep willow, or other shrubs and medium-sized trees. There 

may be an overstory of cottonwood, tamarisk, or other large trees, but this is not 

always the case. In some areas, the flycatcher will nest in habitats dominated by 

tamarisk and Russian olive. One of the most important characteristics of the 

habitat appears to be the presence of dense vegetation, usually throughout all 

vegetation layers present. Almost all southwestern willow flycatcher breeding 

habitats are within close proximity (less than 20 yards) of water or very saturated 

soil. This water may be in the form of large rivers, smaller streams, springs, or 

marshes. At some sites, surface water is present early in the nesting season, but 

gradually dries up as the season progresses. Ultimately, the breeding site must 

have a water table high enough to support riparian vegetation 



4-29 




AGFD records show that no southwestern willow flycatcher has been detected in 

the study area. Southwestern willow flycatchers were not observed during a 

pedestrian survey of the study area. Southwestern willow flycatcher surveys were 

conducted at the Ina Road crossing of the Santa Cruz River in 2003, located 

approximately 3 miles south of the study area. No southwestern willow flycatchers 

were detected. The closest known breeding territory was detected near the 

confluence of Cienega Creek and Gardner Canyon, which is located approximately 

30 miles south of the study area, although breeding was not detected in 2003. 

Yellow-billed Cuckoo 

The yellow-billed cuckoo is listed as a candidate species. Suitable habitat for the 

species in the western United States is limited to narrow, and often widely 

separated, riparian cottonwood-willow galleries (salt cedar is also used by the 

cuckoo). Dense understory foliage appears to be an important factor in nest site 

selection, while cottonwood trees are an important foraging habitat. 

Surveys were conducted by Sage Landscape Architecture and Environmental, Inc. 

from August through September 2002 along four reaches of the Santa Cruz River 

and four reaches of the Tanque Verde Creek near Tucson. Survey areas included 

suitable habitat for yellow-billed cuckoos that contained mixed broadleaf riparian 

deciduous trees with stratified canopy. Using call tapes, five yellow-billed cuckoos 

were identified at four separate sites, two individuals along the Santa Cruz River 

and three along the Tanque Verde Creek. All appeared to be unpaired males. 

Impacts 


The no build alternative would have no impacts upon threatened and endangered 

species in the project area. 


The study area does contain suitable habitat for the CFPO. Suitable habitat consists 

of riparian vegetation along the Santa Cruz River and Arizona Upland vegetation 

in the vicinity of Linda Vista Boulevard. Some locations in the study area do not 

contain suitable pygmy-owl habitat. These locations include areas of intense urban 

development and associated infrastructures that no longer support appropriate 

vegetation components. AGFD records indicate that pygmy-owls are known to 

occur approximately two miles north of the study area, although surveys for 

CFPOs conducted since 2001 have not detected pygmy-owls in the study area. 

Of the approximately 15 acres of proposed critical habitat for the CFPO within the 

study area, approximately 12 acres would be temporarily impacted by construction 

activities and approximately 0.5 acres beneath the proposed Santa Cruz River 

bridges would be permanently impacted by the project. However, based on the 

proposed replacement of trees, habitat connectivity important to successful 

dispersal would be maintained or enhanced. 



4-30 





Camino de Mañana would impact vegetation in area of suitable habitat. Vegetation 

impacts in suitable habitat would be limited to riparian vegetation along the Santa 

Cruz River and desertscrub vegetation in upland areas along Linda Vista 

Boulevard and El Camino de Mañana. Prior to removal of vegetation during 

construction, the Town of Marana would develop a revegetation plan that would 

comply with the Arizona Native Plant Law (ANPL), and Native Plant Protection 

Ordinances (NPPO) of the Town of Marana and Pima County. In addition, the 

revegetation plan would include Corps’ recommendations from the TRDN 

Feasibility Study (see Mitigation below). As a result of the revegetation plan, the 

value of the vegetation in the disturbed area of the project area would be improved 

by construction of the preferred alternative. 

The preferred alternative is not likely to adversely affect CFPO or its habitat 

because: 1) although pygmy-owls do occur within mean dispersal distance of the 

study area, USFWS is not aware of any nesting pairs within this distance; 2) 

impacts to riparian vegetation would be temporary and would not permanently 

impede use of the Santa Cruz River as a movement corridor; 3) loss of desertscrub 

vegetation does not occur in areas used by pygmy-owls for nesting; 4) width of the 

proposed Twin Peaks Road and noise from traffic should not prevent movement of 

pygmy-owls across it; and, 5) the bridges over the Santa Cruz River would be of 

sufficient height to allow unimpeded wildlife movement underneath. 

The preferred alternative would result in disturbances to suitable habitat to the 

yellow-billed cuckoo. In addition, the species has been documented in the study 

area; therefore, the project may impact individual cuckoos, but is not likely to 

jeopardize the continued existence of yellow-billed cuckoos. 

The Section 7 of the ESA requires federal agencies to ensure that the actions they 

authorize, fund, or carry out do not jeopardize the continued existence of 

endangered species. To comply with Section 7 requirements, FHWA requested 

concurrence with the USFWS on August 4, 2004 which resulted in the USFWS 

concurring that the Preferred Alternative would not jeopardize the endangered 

CFPO nor the yellow-billed cuckoo in a letter dated December 21, 2004 (see 

Appendix B). 

Mitigation 

Prior to construction, the Town of Marana would develop a revegetation plan that 

would incorporate the mitigation discussed below. This revegetation plan would be 

provided to the contractor. Mitigation measures would include revegetation of 

impacted areas along the roadway and the riparian vegetation along the Santa Cruz 

River. Mitigation would include: 

• Disturbed soils would be re-seeded using species native to the project vicinity 

and would mirror the current plant composition to the extent possible. 

• Within upland areas, trees greater than 4 inches diameter at breast height and 

Saguaro cactus that are removed would be replaced within the overall 



4-31 




construction footprint at a 3:1 ratio. Vegetation would be replaced in kind with 

a minimum container size of 15 gallons. These replacements would not occur 

within the clear zone of the roadway. 

• Within the clear zone of the roadway, creosote bush seed would be utilized in 

order to facilitate quick replacement of vegetation cover. 

• Mesquite trees greater than 4 inches diameter at breast height that are removed 

within the high flow channel of the Santa Cruz River would be replaced at a 

3:1 ratio within the overall project limits in accordance with the revegetation 

plan. Vegetation would be replaced in kind with a minimum container size of 

15 gallons. 

• Revegetation of the Santa Cruz River is planned following construction. 

Riparian vegetation in the low flow channel is comprised of cottonwood trees, 

willow trees, mesquite, and seep willow. Riparian trees greater than 4 inches 

diameter at breast height that are removed for construction would be replaced 

in kind at a 3:1 ratio with a minimum container size of 15 gallons. 

• When fully restored, the vegetation within the Santa Cruz River would provide 

continuous tree cover through the project limits. 

• The bottom of the bridges would be approximately 20 feet above the bottom of 

the low flow channel of the Santa Cruz River, which should provide sufficient 

height to allow pygmy-owls and other wildlife to move unimpeded under the 

bridges. 

• The Town of Marana would provide water for all plantings outside the low 

flow channel of the Santa Cruz River for a period of two years to facilitate 

their establishment. 

• The Town of Marana would monitor all plantings for a period of two years, 

starting at the time of planting, on a quarterly basis. Two yearly reports would 

be generated and submitted to the U.S. Fish and Wildlife Service and the 

Arizona Department of Transportation’s Environmental and Enhancement 

Group discussing the progress of the revegetation effort. 

• The revegetation plan would comply with the Arizona Native Plant Law, and 

Native Plant Preservation Ordinances of the Town of Marana and Pima 

County. In addition, the revegetation plan would also include U.S. Army Corps 

of Engineers recommended mitigation measures for the Santa Cruz River 

Channel. 

• The revegetation plan would be developed based on the objectives of the Tres 

Rio del Norte Feasibility Study. Tres Rio del Norte planning objectives related 

to vegetation on the Santa Cruz River include: creating a mesquite bosque at 

higher elevations from the Santa Cruz River bottom on terraces and over-bank 

areas; plant and establish cottonwood and willow tree plant communities along 

the wetted perimeter, and fringe area locations within the Santa Cruz River; 

established wetlands/Cienega at appropriate locations, to create a diverse and 



4-32 




high value project habitat; and, reestablish desertscrub plant communities 

along the degraded upland portions of the Santa Cruz River corridor, 

emphasizing saltbush-wolfberry and mesquite associations as components. 

Conclusion 

Suitable habitat for the CFPO and the yellow-billed cuckoo is present in the 

project area within the Santa Cruz River Channel. Upland vegetation areas near 

Linda Vista Boulevard are also suitable habitat for the CFPO. The pygmy-owl and 

the yellow-billed cuckoo have been documented near the study area, although 

surveys for CFPO conducted in 2001, 2002, 2003, and 2004 have not detected 

pygmy-owls in the study area. Vegetation impacts in suitable habitat would be 

limited to riparian vegetation along the Santa Cruz River and desertscrub 

vegetation in upland areas along Linda Vista Boulevard and El Camino de 

Mañana. USFWS concurred that the Preferred Alternative would not jeopardize 

the endangered CFPO nor the yellow-billed cuckoo in a letter dated December 21, 

2004. The USFWS concluded also that the majority of the project area does not 

support CFPO nesting habitat and that, based on the proposed replacement of 

trees, habitat connectivity important to successful dispersal would be maintained 

or enhanced. Mitigation measures that would be implemented include a 

revegetation plan developed by the Town of Marana prior to removal of vegetation 

during construction. 

Arizona Species of Concern 

Species 

Wildlife of Special Concern in Arizona, as defined by AGFD, are species whose 

occurrence in Arizona is or may be in jeopardy, species with known or perceived 

threats, or species suffering population declines. One state listed species, the 

Fulvous whistling duck (Dendrocygna bicolor), has been documented by AGFD 

as occurring within 2 miles of the study area. 

Fulvous whistling duck 

Fulvous whistling duck are found along rivers, ponds, stock ponds, marshes, and 

swamps. This species has been documented by AGFD as occurring within two 

miles of the study area in the vicinity of the Santa Cruz River. Potential suitable 

habitat in the study area is limited to a small, narrow band of riparian vegetation 

along the Santa Cruz River that lacks sufficient vegetation cover and density to 

support fulvous whistling duck nesting. Fulvous whistling duck were not observed 

during a pedestrian survey of the study area. 

Impacts 


The no build alternative would have no impacts upon Arizona wildlife species of 

concern in the project area. 



4-33 





The preferred alternative would not impact the fulvous whistling duck. Potential 

suitable habitat for the duck in the study area is limited to a small, narrow band of 

riparian vegetation along the Santa Cruz River that lacks sufficient vegetation 

cover and density to support fulvous whistling duck nesting. 

Mitigation 

The preferred alternative would implement measures to minimize impacts to 

vegetation and restore any vegetation losses resulting from construction. The 

fulvous whistling duck would benefit from the mitigation measures outlined in the 

revegetation plan developed for this project. 

Conclusion 

Fulvous whistling duck are documented to occur within two miles of the project 

area; however, potential suitable habitat in the study area is limited to a small, 

narrow band of riparian vegetation along the Santa Cruz River that lacks sufficient 

vegetation cover and density to support fulvous whistling duck nesting. 

Plants 

Threatened/Endangered Species 

Species 

For purposes of this assessment, federally listed plant species include endangered, 

threatened, proposed, or candidate species as defined in the ESA. The list of 

federal species used in this report was developed from the federally listed, 

proposed, and candidate species for Pima County from the USFWS Arizona 

Ecological Field Office website. The species list contains 4 endangered and 1 

candidate species (Table 4-4). 

No federally listed plant species occur in the project area because the project area 

is either: 1) clearly outside of the known geographic or elevational range of the 

species; or, 2) does not contain habitat characteristics known to support the 

species. 

Common Name 

Table 4-4. Special Status Plant Species 

Scientific Name Status 

Huachuca Water Umbel Lilaeopsis schaffneriana spp. recurva Endangered 

Kearney Blue Star Amsonia kearneyana Endangered 

Nichol’s Turk’s Head Cactus Echinocactus horizonthalonius var. Endangered 

nicholii 

Pima Pineapple Cactus Coryphantha scheeri var. robustispina Endangered 

Acuna cactus Echinomastus erectocentrus var. acunensis Candidate 



4-34 




Impacts 


No federally listed plant species occur in the project area; therefore, the no build 

alternative would have no impacts upon these species. 


No federally listed plant species occur in the project area; therefore, the preferred 

alternative would have no impacts on these species. 

Mitigation 

No federally listed plant species occur in the project area; therefore, no mitigation 

for federally listed plant species is necessary. 

Conclusion 

No federally listed plant species occur in the project area; therefore no impacts 

would occur to these species. 

Arizona Native Plant Law Species 

Species 

One Salvage Restricted plant species listed under the ANPL, the Tumamoc 

globeberry (Tumamoca macdougalii), has been documented by AGFD as 

occurring within 2 miles of the study area. This species is found on hot, dry, southfacing 

slopes of basalt and along desert washes. This species was not observed 

during a pedestrian survey of the study area. 

In addition, native plants protected by the ANPL, Marana NPPO and Pima County 

NPPO, such as paloverde, ironwood, mesquite and cactus, are present within the 

project area. 

Impacts 


The no build alternative would not impact species protected by the ANPL or 

Marana or Pima County PPOs. 


Existing land uses have disturbed suitable habitat in the project area and natural 

vegetation in these disturbed areas has been removed. Much of the project area 

would occur within previously disturbed areas. Tumamoc globeberry were not 

observed during field reconnaissance of the project area, but undetected 

individuals may be impacted by construction in undisturbed areas. 

Native plants protected by the ANPL, Marana NPPO and Pima County NPPO are 

present within the project area and would be impacted by construction of the 

preferred alternative. Prior to construction, a native plant survey would be 



4-35 




conducted to determine the types of species and number of individual plants that 

would be impacted. 

Mitigation 

To protect vegetation resources in the project area, a revegetation plan would be 

developed prior to construction activities. The Town of Marana would develop a 

Native Plant Protection Plan (NPPP) in accordance with local ordinances. 

Protected native plants within the construction limits would be impacted by the 

preferred alternative; therefore, the ADOT Roadside Development Section would 

notify the Arizona Department of Agriculture (ADOA) at least 60 days prior to the 

start of construction to afford commercial salvagers the opportunity to remove and 

salvage these plants. 

Conclusion 

One Salvage Restricted plant species listed under the ANPL, the Tumamoc 

globeberry, has been documented by AGFD as occurring within 2 miles of the 

study area. Tumamoc globeberry were not observed during a pedestrian survey of 

the study area and existing land use has disturbed suitable habitat for the Tumamoc 

globeberry. In addition, native plants protected by the ANPL, Marana NPPO and 

Pima County NPPO are present within the project area and would be impacted by 

construction of the preferred alternative. A revegetation plan would be developed 

prior to construction activities and a NPPP would be developed by the Town of 

Marana to address impacts to native vegetation and develop mitigation measures. 

Vegetation, Riparian Habitat, and Wetlands 


Vegetation in the study area is a mosaic of natural upland vegetation, small dry 

ephemeral washes, disturbed and re-established riparian areas, wetland vegetation 

of the Santa Cruz River, and disturbed and landscaped vegetation associated with 

residential housing, commercial businesses, and light industry. Most of the natural 

vegetation in the study area occurs: 1) within the high flow channel of the Santa 

Cruz River; and, 2) along Linda Vista Boulevard, particularly between El Camino 

de Mañana (west) and Hartman Lane (east). 

Natural vegetation in the study area is representative of three vegetation 

communities: 1) Arizona Uplands; 2) Riparian Scrub; and, 3) Cottonwood/Willow 

Riparian Forest. Arizona Uplands vegetation exists in the upland areas along Linda 

Vista Boulevard and is characterized by foothills palo verde, saguaro, velvet 

mesquite, triangle-leaf bursage, and cholla cactus. The most intact Arizona 

Uplands Vegetation occurs along Linda Vista Boulevard west of Hartman Lane. 

Arizona Uplands vegetation along Linda Vista Boulevard east of Hartman Lane 

has been fragmented as a result of residential development. No natural landscapes 

of Arizona Upland vegetation remain on the west side of the study area because of 

the Continental Ranch housing development. Small and scattered remnant Sonoran 



4-36 




Desertscrub vegetation is found in the light industrial area west of I-10 to the Santa 

Cruz River and east of I-10 to Linda Vista Boulevard. 

Riparian Scrub is associated with dry ephemeral washes that occur throughout the 

study area, but occur in the highest density and most natural condition east of El 

Camino de Mañana along Linda Vista Boulevard. Riparian Scrub vegetation is 

characterized by plant species found in adjacent desertscrub habitat, such as 

foothill palo verde and velvet mesquite, although riparian plants are typically 

larger and often occur at higher densities than those in upland areas. Plants in this 

association grow in rows along the margins of the watercourses and are clearly set 

apart from the intervening vegetation of the uplands. Plant species present include 

foothills paloverde and velvet mesquite. Most of the washes have been stabilized 

within Continental Ranch and within the residential housing areas along Linda 

Vista Boulevard. Stabilized washes in these areas have straightened stream 

channels, improved bank protection (often using soil cement), and are cleared of 

most vegetation. 

Cottonwood/Willow Riparian Forest occurs along the Santa Cruz River. This 

vegetation association is characterized by a narrow band of small to moderatesized 

(10 to 30 feet in height) Freemont cottonwood and Goodding willow. 

Additional plant species in the area include seep willow, cattail, bulrush, tamarisk, 

and velvet mesquite. Along this reach of the Santa Cruz River, Riparian Forest is 

restricted to small, scattered stands separated by areas of low shrubs such as 

desertbroom and seep willow. The Riparian Forest is restricted to the low-flow 

channel where the influence of perennial effluent water flow from Pima County's 

Roger and Ina Road Treatment Plants allows this vegetation to survive in an 

otherwise dry river. Vegetation outside the low-flow channel, in the high-flow 

channel, is characteristic of disturbed areas. This vegetation consists of 

desertbroom, shrub-like velvet mesquite, four-wing saltbush, and grasses. In 

addition, large areas of bare soil characterize the high-flow channel. 

Riparian habitat includes the trees, other vegetation, and physical features 

normally found on the banks and floodplains of rivers, streams, and other bodies of 

water. Although riparian areas occupy a small area, they support a diversity of fish 

and wildlife species. In addition, riparian areas can help reduce flood flows and 

flood damage, improve groundwater recharge, reduce the damaging chemicals and 

other compounds that reach open water, and reduce wind erosion on adjacent 

lands. Riparian areas also provide important open space and recreational 

opportunities. Riparian areas approximate the jurisdictional waters presented in 

Figure 4-3. 

Wetlands are low-lying areas typically saturated with moisture that typically 

provide habitat for a variety of plant and animal species, including many 

endangered species. The state of Arizona has no wetland protection program, but 

wetlands are regulated by the Corps under Section 404 of the CWA. A regulated 

wetland is one that meets 3 criteria: 1) hydrophytic vegetation; 2) hydric soils; and, 

3) wetland hydrology (the presence of water). 



4-37 




The extent and development of potential wetlands and riparian vegetation of the 

Santa Cruz River contained within the study area varies significantly from year to 

year as it is frequently scoured by flood events. The distribution of potential 

wetlands is also regulated by discharges of effluent from the Ina Road Wastewater 

Treatment Plant. These discharges provide the water that supports potential 

wetland and riparian habitats within the low flow channel of the Santa Cruz River. 

Typical potential wetland plant communities found in these areas contain 

Goodding willow, cattail, smartweed, with some scattered tamarisk and 

cheesebush. 

Within the low flow channel of the Santa Cruz River, potential wetlands were 

identified, all of which were adjacent to the current Santa Cruz River channel. 

Areas away from the current channel had indicators for wetland hydrology, 

primarily due to the frequency of flooding, but the other criteria were not present 

in these areas. 

Impacts 


The no build alternative would not affect existing vegetation, wetlands, or riparian 

habitat within the project area. 


The preferred alternative would result in limited disturbances to natural vegetation 

in the areas of the crossing of the Santa Cruz River and the area along El Camino 

de Mañana and Linda Vista Boulevard. The area along El Camino de Mañana and 

Linda Vista Boulevard is characterized by small ephemeral washes and 

desertscrub vegetation of the Arizona Uplands Subdivision, which provides a 

diversity of wildlife habitats. Although some disturbance of natural vegetation 

would occur along Linda Vista Boulevard with the proposed improvements, the 

areas of disturbance would be limited and revegetated in accordance with the 

revegetation plan (see Threatened and Endangered Species Section, page 4-26). In 

addition, most of the area along Linda Vista Boulevard and El Camino de Mañana 

that would be affected by the proposed improvements has been disturbed for 

construction and maintenance of the existing roadway; therefore, no substantial 

impacts to the value of riparian habitat would occur. 

The preferred alternative would have both temporary and permanent impacts to 

riparian habitat and potential wetlands in the area of the crossing of the Santa Cruz 

River. Vegetation removal in the low flow channel would be the minimum 

required for the construction of the proposed improvements. Impacts to vegetation 

in the high flow channel of the Santa Cruz River would be minimal because 

vegetation in this area is sparse and characteristic of disturbed areas. Vegetation 

that must be removed would be restored according to the revegetation plan 

developed for this project. 

The bridges spanning the low flow channel of the Santa Cruz River would have 

both temporary and permanent impacts on potential wetlands in the low flow 



4-38 




channel. Temporary impacts would include the removal of riparian vegetation 

within the area of construction of the bridge structure and embankments. Potential 

wetlands and riparian vegetation would be restored following construction 

according to the revegetation plan. Permanent impacts would result from the 

shading of riparian vegetation from the overhead bridges. Shading of vegetation 

reduces the amount of direct sunlight available to vegetation resulting in plants of 

smaller size and the establishment of more shade tolerant plants. Approximately 

0.07 acres of potential wetland would be permanently lost due to shading. 

The low flow channel of the Santa Cruz River would be widened to compensate 

for the roadway and bridge embankment fill placed with the high flow Santa Cruz 

River channel (see Floodplain Section, page 4-14). This action would temporarily 

impact approximately 1.5 acres of riparian habitat in the low flow channel of the 

Santa Cruz River. Because of the widening of the low flow channel that would 

occur with the preferred alternative, the area available for the establishment of 

riparian habitat would be larger and the size and quality of riparian habitat to be 

used by wildlife would be improved. As a result of the revegetation plan, the value 

of the vegetation in the disturbed area of the floodplain would be improved by 

construction of the preferred alternative. 

Mitigation 

The preferred alternative would implement measures to minimize impacts caused 

by the proposed improvements and to restore vegetation, riparian habitat, and 

potential wetlands impacted by the preferred alternative. Vegetation removal 

would be the minimum required for the construction of the proposed 

improvements. Prior to the removal of vegetation during construction, the Town of 

Marana would develop a revegetation plan that would comply with the ANPL, and 

NPPOs of the Town of Marana and Pima County. The revegetation plan would 

include Corps’ recommendations from the TRDN Feasibility Study. The main 

constituents of the revegetation plan were discussed earlier (see Threatened and 

Endangered Species Section, page 4-26). During design, a wetland delineation 

would be completed. In the event that jurisdictional wetlands are impacted by the 

preferred alternative, coordination with the Corps would occur and appropriate 

permits would be obtained. 

Conclusion 

The preferred alternative would have temporary and permanent impacts to 

vegetation, riparian habitat, and potential wetlands within the project area. These 

impacts would be minimized by limiting the amount of vegetation removed to the 

minimum required for the construction of the proposed improvements and through 

the development and implementation of the revegetation plan. The proposed 

improvements would provide a larger area for riparian vegetation through a 

widening of the low flow channel of the Santa Cruz River and the revegetation 

plan would restore or improve the value of riparian habitat in disturbed areas. 



4-39 




Invasive Species 


Under EO 13112, dated February 3, 1999, projects which occur on federal lands or 

are federally funded must “subject to the availability of appropriations, and within 

Administration budgetary limits, use relevant programs and authorities to: 1) 

prevent the introduction of invasive species; 2) detect and respond rapidly to, and 

control, populations of such species in a cost-effective and environmentally sound 

manner; 3) monitor invasive species populations accurately and reliably; and, 4) 

provide for restoration of native species and habitat conditions in ecosystems that 

have been invaded.” 

Highway corridors provide opportunities for the movement of invasive species 

through the landscape. Invasive species can move on vehicles and in the loads they 

carry. Invasive plants can be moved from site to site during spraying and mowing 

operations. Weed seed can be inadvertently introduced into the corridor during 

construction on equipment and through the use of mulch, imported soil or gravel, 

and sod. Some invasive plant species might be deliberately planted in erosion 

control, landscape, or wildflower projects. 

Impacts 


The no build alternative would not actively contribute to the spread of invasive 

species. The Town of Marana, ADOT, and Pima County would continue to utilize 

current management practices for the control of invasive species in the project 

area. 

Preferred Alterative 

Through the use of detailed surveys and the mitigation measures described below, 

the preferred alternative would not contribute to the spread of invasive species in 

the project area. 

Mitigation 

During final design, invasive species surveys would occur to determine if invasive 

species are present. 

The Town of Marana would survey individual construction segments of the project 

area outside the Arizona Department of Transportation’s right-of-way to determine 

the invasive species present within the segment, treat these species prior to 

construction in accordance with the Natural Resources Section of the Intermodal 

Transportation Division of the Arizona Department of Transportation’s invasive 

species management plan, and continue any necessary treatments following 

construction completion. 

The Natural Resources Section of the Intermodal Transportation Division of the 

Arizona Department of Transportation would survey individual construction 



4-40 




segments of the project area within the Arizona Department of Transportation’s 

right-of-way to determine the invasive species present within the segment, treat 

these species prior to construction in accordance with the Section’s invasive 

species management plan, and continue any necessary treatments following 

construction completion. 

The contractor would clean all earth-moving and hauling equipment prior to its 

entering the construction site to prevent the introduction of invasive species. 

Additional invasive species mitigation, if needed, would be developed during final 

design using the invasive species survey. All disturbed soils would be seeded 

using native species to help prevent the reestablishment of invasive species. 

Conclusion 

As a result of the implemented mitigation measures, the preferred alternative 

would not assist in the spread of invasive species. 

Visual Resources 

The complete results of the visual resource investigations are presented in the 

document Interstate 10 Traffic Interchange at Twin Peaks/Linda Vista Visual 

Impact Analysis Report, dated February 5, 2004. Readers are referred to this report 

for the detailed findings; however, the results are summarized below. 

In a roadway improvement project, visual resources are considered from two 

perspectives: 1) the view from the roadway to motorists; and, 2) the view of the 

roadway to the surrounding community. Visual resources and effects to these 

resources are defined by identifying key views and considering community goals 

and preferences. 

Community goals and preferences are established in planning documents that 

address protection of visual resources. Two Town of Marana planning documents, 

the Town of Marana General Plan Update (November 2002) and the Park, Trail, 

and Open-Space System Master Plan (July 2000), address visual resources. The 

General Plan provides overall direction for future growth and development. While 

the General Plan does not dictate parcel-level land use decisions, it integrates land 

use, resource conservation, transportation, economic development, and public 

facilities and services into a comprehensive and coordinated strategy. Although the 

General Plan expresses clear goals of protection of significant scenic value 

viewsheds, no specific policies or strategies to address transportation facilities are 

included. Marana’s Park Plan was developed to accomplish several goals, one of 

which was to protect significant natural open space areas. The Park Plan describes 

open space areas like the Tortolita Mountains, Saguaro National Park (SNP), and 

unique biological communities such as the Santa Cruz River riparian area and the 

Tortolita Fan Ironwood Forest as important visual resources valued by the 

community. 



4-41 





Foreground Views 

Foreground views in the study area include the low flow channel of the Santa Cruz 

River Floodplain, containing riparian vegetation and perennial effluent dominated 

water. Other foreground views include I-10, the UPRR, and TEP transmission 

lines. 

Background Views 

Middle ground views from both Twin Peaks Road and along I-10 include the Santa 

Cruz River. The Santa Cruz River is an important water feature that runs in a 

northwesterly direction through the study area. The width of the Santa Cruz River 

is constricted in places by bank protection and flood control measures. Suburban 

development characterizes the area west and southwest of the study area and 

industrial land uses (portland cement plant) are visible to the southeast. 

The most memorable views within the study area are the background views: the 

Tucson Mountains to the west and southwest; the Rincon Mountains to the 

southeast; the Catalina Mountains to the east; and Tortolita Mountains to the 

northeast. 

Visual Quality Objectives 

Important natural visual resources within the study area (landform, water, 

vegetation, and natural colors) and cultural visual resources (ranching and grazing 

lands, residential, commercial, and industrial developments) were assessed and 

evaluated following the guidelines of the FHWA Visual Impact Assessment for 

Highway Projects (1981), the Bureau of Land Management (BLM) Visual 

Resource Management Manual (1981), and Pima County Department of 

Transportation and Flood Control District (PCDOT&FCD). The objective of the 

visual impact assessment is to better provide roadway users and community 

project viewers with a transportation system that is pleasing to the senses, 

assimilates the visual qualities of the community’s visual resources into its design, 

and makes the project compatible with the community at large. 

Impacts 

Visual impacts of the proposed improvements were determined by assessing the 

change in visual resources caused by the preferred alternative and then by 

predicting viewer response to that change of visual resources. To assess the visual 

resource change, the visual compatibility and/or visual contrast of the proposed 

alternative with the visual character of the existing landscape was examined. To 

predict viewer response, viewer exposure and viewer sensitivity was considered. 

Viewer exposure considers the physical limits of the views and the number of 

affected viewers. Viewer sensitivity considers viewer expectations based on the 

existing environment and the extent to which visual elements may be important to 

the viewer. The visual impacts of the preferred alternative were analyzed from six 



4-42 




viewpoints and then given a Visual Impact Rating (VIR) of: low, moderate, 

moderately high, or high. 


The no build alternative would have no effect on visual resources within the 

project area. 


There are general visual impacts that would affect the entire project area, not only 

views from specific viewpoints. The visual short term impacts during construction 

would affect most viewpoints. Grading would affect existing topography, 

vegetation, and vistas and large construction vehicles would be visible from 

adjacent land. Barren slopes and the project in various stages of development 

would be visible intermittently throughout project construction. 

Offsite structures visible from the proposed roadway that would impact visual 

quality are the Arizona Portland Cement plant, commercial land uses along the 

frontage roads, and the TEP transmission line. These visual elements, which would 

be considered less desirable, would become more noticeable when viewed from 

the proposed elevated roadway section; however, the proposed elevated roadways 

would enhance the roadway users’ view of the Tucson, Santa Catalina, and 

Tortolita Mountains, which would be desirable views. 

View from Twin Peaks Road 

The preferred alternative would affect the existing open space views to the east 

from Continental Ranch. The proposed improvements would blend with existing 

land uses and traffic near the interstate; however, the alternative would contrast 

with the open space views and landscapes in the floodplain. In addition, residents 

on the south side of Twin Peaks Road would have views blocked by a proposed 

17-foot tall noise wall. Lighting at the signalized intersections and light and glare 

from vehicle headlights would be visible also. In this area, there would be a 

moderate adverse change to the existing visual resource and a moderate viewer 

response; therefore, views from Twin Peaks Road would be moderately impacted. 

View from the High Flow Channel of the Santa Cruz River 

The preferred alternative would allow greater access to floodplain views. 

Background views to the west (Tucson Mountains) would be enhanced, because of 

the elevated roadway; however, views of the developed areas would be affected 

negatively by the proposed 17-foot tall noise walls on the south side of Twin Peaks 

Road. Depending on the vantage point, background views to the east may be 

obstructed by the interchange/bridges or enhanced by the elevated roadway. In this 

area, there would be a moderate adverse change to the existing visual resource and 

a moderate viewer response; therefore, views from the high flow channel of the 

Santa Cruz River would be moderately impacted. 



4-43 




View from the Low Flow Channel of the Santa Cruz River 

The preferred alternative would enhance access to views of the riparian area; 

however, the loss of native vegetation along the low flow channel would be a 

visual impact from all views. Depending on the vantage point, views of the Tucson 

Mountains would be enhanced, but some views to the east may be obstructed by 

the interchange/bridges. In this area, there would be a moderate adverse change to 

the existing visual resource and a moderate viewer response; therefore, views from 

the low flow channel of the Santa Cruz River would be moderately impacted. 

View from the I-10 Westbound and Eastbound Frontage Roads 

The preferred alternative would improve the appearance of the existing 

unattractive frontage roads. The proposed roadways would blend with existing 

land uses. In this area, there would be a minor adverse change to the existing 

visual resource and low viewer response to the change; therefore, impacts to views 

from the I-10 frontage roads would be low. 

View from I-10 

The preferred alternative, in particular the bridge over the interstate, would be a 

low adverse change to the existing visual quality along I-10; however, the project 

would enhance the existing visual resource. In this area, there would be a high 

adverse change to the existing visual resource and a moderate viewer response; 

therefore, impacts to views from the I-10 frontage roads would be low. 

View from Linda Vista Boulevard/El Camino de Mañana 

The preferred alternative would obstruct background views to the west. In 

addition, a rural road would change to an urban roadway appearance. In this area, 

there would be a moderate adverse change to the existing visual resource and a 

moderate viewer response; therefore, impacts to views from Linda Vista 

Boulevard and El Camino de Mañana would be moderate. 

Mitigation 

The goals of visual impact mitigation are to provide the user and the viewer of the 

roadway with a transportation system that is pleasing to the senses, enhances the 

aesthetic character of the roadway corridor, assimilates the qualities of the 

community’s visual resources into its design, and makes the roadway more 

compatible with the community-at-large. To design a facility that meets the 

aesthetic needs of the community, the project team would coordinate with the 

community, state and local agencies, and private interest groups. 

The Town of Marana would apply the following visual mitigation measures. 

• Structural elements such as walls, bridges, concrete barriers, and abutments 

would be constructed of materials with color and texture qualities that 

blend into the existing landscape. Architectural treatments would be 

applied to the proposed Twin Peaks Road bridge over I-10 and other 



4-44 




visible structures to enhance the driver’s perception of Marana and to be in 

accordance with similar projects on I-10 in the Tucson area. 

• During construction, the contractor would follow Arizona Department of 

Transportation’s Standard Specifications for Road and Bridge 

Construction, Section 104.09 Prevention of Landscape Defacement; 

Protection of Streams, Lakes and Reservoirs (2000 Edition) and the Water 

Quality Standards in Title 18, Chapter 11 of the Arizona Administrative 

Code as administered by the ADEQ. 

• Erosion control techniques such as slope rounding would be utilized, as 

necessary, to minimize impacts to visual quality. 

• The contractor would reduce visual impacts during construction by 

screening equipment storage and staging areas and by storing excavated 

material and debris in areas less visible to the public. 

• Intersection lighting would be designed to minimize light pollution of night 

skies and limit glare into neighborhoods. 

• Methods of reducing headlight impact to residents of Continental Ranch 

would be considered in final design. 

Conclusion 

As a result of the mitigation measures, visual impacts to the project area would be 

minimized and a visually enhanced traffic interchange would be developed that 

would blend with the surrounding area. 

Air Quality 

The EPA established National Ambient Air Quality Standards (NAAQS) for six 

criteria pollutants (ground level ozone (O3), carbon monoxide (CO), nitrogen 

dioxide (NO2), sulfur dioxide (SO2), particulate matter, and lead). Table 4-5 

presents the federal and state primary (health based) and secondary 

(aesthetic/economic based) standards for the pollutants of concern in the study area 

and the averaging period over which the standard is measured. 


The Pima County Department of Environmental Quality (PDEQ) operates air 

quality monitoring stations at various sites throughout Pima County to monitor the 

levels of the two major air pollutants of concern in this area: particulates (PM10 

and PM2.5), and CO. The closest of these monitoring stations to the study area is 

9597 North Coachline Boulevard, approximately 2,000 feet north of Twin Peaks 

Road. This monitor was established in March of 2001 to determine fine particle 

concentrations in a residential neighborhood. The most recent reported results 

from this site is compared to the NAAQS in Table 4-6. 



4-45 




The monitoring data indicate that the study area generally meets the NAAQS for 

monitored pollutants; however, particulate matter and CO are of general concern 

in the study area and Pima County. The project area lies completely within the 

boundaries of the Rillito Planning Area, which has been designated by EPA as a 

moderate nonattainment area for PM10. As opposed to the remainder of Pima 

County, which is under the auspices of PDEQ, the ADEQ has regulatory authority 

in the Rillito Planning Area. The primary sources of particulate emissions in this 

area include the Arizona Portland Cement Company, construction, unstabilized 

river banks, agriculture, unpaved roads, and unstabilized road shoulders. The 

Rillito PM10 State Implementation Plan (SIP) was submitted to EPA in April 1994, 

but was never approved by EPA. However, the SIP does not include extraordinary 

particulate (dust) control mechanisms. According to ADEQ, compliance with Pima 

County’s Natural Events Action Plan (discussed in the following paragraph), 

ADOT standard specifications for dust suppression during construction, and the 

completion of a SWPPP would comply with the submitted Rillito Planning Area 

SIP. 

Table 4-5. National and State Ambient Air Quality Standards 

National and State Standards 

Pollutant Averaging Period Primary Secondary 

Carbon Monoxide 

(CO) 

Suspended 

Particulate Matter 

(PM10) 

8-Hour 9 ppm No Standard 

1 Hour 35 ppm No Standard 

24-Hour 

150 µg/ 

m 3 

Same as Primary Standard 

Annual Arithmetic 

50 µg/ m 

Mean 

3 Same as Primary Standard 

Source: EPA (49 CFR 50). 

Abbreviations: ppm: parts per million, µg/m 3 : micrograms per cubic meter 

Although still considered an attainment area, Pima County exceeded the PM10 

NAAQS six times in 1999. As a result, PDEQ developed a Natural Events Action 

Plan (NEAP) to protect public health, educate the public about high wind events, 

mitigate health impacts from future events, and identify and implement control 

measures for man-made sources of dust. The NEAP (and the ensuing Pima County 

ordinance) requires an activity permit from the PDEQ before activities such as 

earthmoving, trenching, or road construction are conducted. The ordinance also 

limits the amount of dust generated from these activities to a maximum opacity 

(cloudiness) of 20 percent. In addition to the NEAP, dust generation is also limited 

through grading permits issued by the Town of Marana and by ADOT standard 

specifications for dust suppression during construction. 



4-46 




Table 4-6. 2002 Monitoring Data from Coachline Site compared to NAAQS 

Site/Location Pollutant (Averaging Period) 

Federal 

Standard 

Monitored 

2002 Value 

PM2.5 (maximum 24-hour 65 µg/m 

concentration) 

3 37.0 µg/m 3 

Coachline (9597 

Coachline Boulevard) 

PM2.5 (annual arithmetic mean 

concentration) 

15 µg/m 3 13.0 µg/m 3 

Source: PDEQ 

In addition to the requirements discussed above, additional particulate restrictions 

apply in the area. SNP, which is within approximately 3 miles of the project area, 

is a listed Federal Class I area subject to special particulate matter provisions. 

Class I areas, such as national parks, national wilderness areas, and national 

monuments are granted special air quality visibility protections under the federal 

Clean Air Act; however, these protections apply to stationary sources of pollutants 

(i.e. manufacturing and mining) and not to mobile sources of pollutants (motor 

vehicles). 

CO concentrations within the study area are determined by pollutants emitted into 

the airshed (primarily from motor vehicles) and the lack of pollutant dispersion 

due to topographical and meteorological characteristics of the Tucson basin. As a 

result of these conditions, exceedances of the CO NAAQS were relatively 

common in the 1970s; however, no CO violations have been recorded since 1984. 

The improvement in CO levels resulted in the Tucson Air Planning Area (TAPA) 

being redesignated by EPA to an attainment area for CO in 2000. A limited 

maintenance plan was approved that establishes procedures and contingency 

measures to be implemented, if necessary, in the future. The plan requires 

additional monitoring and modeling of CO concentrations at intersections with the 

worst level of service and highest ADT. A limited maintenance plan applies to 

areas whose monitored CO concentrations are equal to or less than 85% of the 8hour 

CO NAAQS for at least 8 consecutive quarters. 

PAG has the responsibility of maintaining the TAPA SIP. In this role, PAG 

determines the compliance of local transportation implementation programs and 

long range transportation plans with the SIP and conducts the microscale CO 

modeling analyses as required by the limited maintenance plan to address those 

areas most susceptible to CO violations. 

Impacts 


The no build alternative would not provide an additional access point to I-10 nor a 

grade-separated crossing of the UPRR; therefore, traffic congestion on area 

roadways would not be improved and would worsen over time. Increasing traffic 

congestion would result in higher emissions from stop and go traffic and idling 

vehicles, which would negatively impact air quality. Pedestrian and bicycle facility 



4-47 




connectivity within the area would not be improved; therefore, increased use of 

less polluting alternative transportation modes would not be expected. 

The 1990 Clean Air Act Amendments require transportation projects to conform to 

(be consistent with) air quality implementation plans. To be a conforming project, it 

must be part of an approved transportation plan and transportation improvement 

program. The Twin Peaks Road TI is part of the approved 2025 Regional 

Transportation Plan and 2005-2009 Transportation Improvement Program. As a 

result, the no build alternative would not be consistent with the approved 

transportation plan and program and no benefits to regional air quality would 

occur. 


The proposed project is located within an area that is in attainment for all criteria 

pollutants except PM10. The project is within the boundaries of the Rillito Planning 

Area, which has been designated by EPA as a moderate nonattainment area for 

PM10. However, compliance with Pima County’s NEAP, ADOT standard 

specifications for dust suppression during construction, and a SWPPP would 

comply with the Rillito Planning Area SIP. Construction-related soil disturbance 

and operation of heavy equipment would produce an increase in particulate matter 

during roadway construction, but these impacts would be short-term in nature and 

mitigated as described below. 

The Twin Peaks Road TI is part of the approved 2025 Regional Transportation 

Plan and 2005-2009 Transportation Improvement Program. The proposed project 

is located within the TAPA in Pima County. This project is in an area that 

complies with the NAAQS for CO and would have no negative effects on CO 

levels in the area. The project involves construction of a new TI with I-10 and 

associated improvements, which would reduce roadway congestion and associated 

CO emissions. Pursuant to 40 CFR 93.116, this project is in conformity. 

Mitigation 

Prior to initiating any construction activities, such as earthmoving, trenching, or 

road construction, the contractor would apply for and be granted an activity permit 

from the PDEQ and a grading permit from the Town of Marana. The contractor 

would monitor dust generation from the construction area and limit the amount of 

dust generated to a maximum opacity of 20 percent. The contractor would follow 

ADOT standard specifications for dust suppression during construction and shall 

comply with the SWPPP prepared for this project. 

During construction, the contractor would control, reduce, remove, or prevent air 

pollution in all its forms, including air contaminants, in the performance of the 

contractor’s work in accordance with Arizona Department of Transportation’s 

Standard Specifications for Road and Bridge Construction, Section 104.08 

Prevention of Air and Noise Pollution (2000 Edition). 



4-48 




Conclusion 

As a result of these mitigation measures, the proposed project would have only 

temporary, short-term, and minimal impacts to particulate levels during project 

construction. The project would decrease traffic congestion in the study area, 

which would improve overall air quality. Pedestrian and bicycle facility 

connectivity within the area would be improved; therefore, an increased use of less 

polluting alternative transportation modes would be expected. 

Noise 

ADOT’s Noise Abatement Policy(NAP) for Federal Aid Projects (March 21, 2000) 

defines a traffic noise impact as: 

• When the predicted level approaches or exceeds the FHWA’s NAC. ADOT 

defines “approach” as being within 3 dBA of the appropriate NAC. Under 

this policy, residential impacts would occur when the future Leq(h) value is 

64 dBA or greater; or, 

• When the predicted level substantially increases over existing noise levels. 

“Substantial” is defined as an increase of 15 dBA or higher. 


The complete results of the traffic noise analyses are presented in the document 

Interstate 10 Traffic Interchange at Twin Peaks/Linda Vista Final Traffic Noise 

Analysis Report, dated September, 2004. Readers are referred to this report for the 

detailed findings; however, the results are summarized below. 

Traffic Noise Monitoring 

Existing traffic noise conditions were assessed using traffic noise monitoring. 

Field monitoring of traffic noise during peak traffic periods was conducted on 

December 4, December 16, and December 17, 2003. Monitoring occurred between 

approximately 7:00 AM and 8:00 AM and between 4:00 PM and 6:00 PM. Noise 

levels were measured at seven locations near roadways in the study area using an 

integrating sound level meter. 

The field monitoring results are presented in Table 4-7. Measured noise levels 

ranged from 55 dBA near Twin Peaks Elementary School to 73 dBA west of the I- 

10 Frontage Road at Linda Vista Boulevard. As expected, the highest noise 

readings were near I-10. 

Traffic Noise Modeling 

Computer modeling of traffic noise can be utilized at a greater number of locations 

along a corridor than noise monitoring, modeling can be adjusted to replicate 

highest traffic volumes and other parameters, and modeling can be used to assist in 

traffic noise mitigation design. For these reasons, noise impacts resulting from 

existing roadway traffic were analyzed using STAMINA/Optima 2.0 (STAMINA). 



4-49 




STAMINA is a traffic noise prediction model developed by FHWA that utilizes 

site-specific information including traffic volume, speed, vehicle classification 

data, roadway lane configuration, and site acoustical characteristics to predict 

peak-hour traffic noise at selected receiver locations. 

Table 4-7. Traffic Noise Monitoring Results 

Monitoring Location and (Beginning Times) 

Location 1 South Side of Linda Vista Boulevard, East of 

Hartman Lane (7:15 – 7:36 AM) 

Location 2 West of I-10 at Linda Vista Boulevard (6:56 – 

7:20 AM) 

Location 3 South Side of Twin Peaks Road, West of Palm 

Canyon Drive (7:52 – 8:07 AM) 

Location 4 West Side of Twin Peaks Elementary School 

(5:21 – 5:42 PM) 

Location 5 East of I-10 at Camino de Mañana Road (4:27 

– 4:50 PM) 

Location 6 Mountain View High School/Arthur Pack Golf 

Course (4:08 – 4:29 PM) 

Location 7 North Side of Twin Peaks Road, West of 

Sunflower Ridge Road (5:10 – 5:32 PM) 

Noise Level (dBA) 

(Highest Reading Per Site) 

To ensure that the results of STAMINA accurately reflected actual conditions, 

traffic (volumes and numbers of medium and heavy trucks) and site data (location 

and height of walls) were also collected during field noise measurements. These 

field conditions were entered in the computer model and the noise levels predicted 

by the model were compared to those measured in the field. This adjustment 

process identifies minor modifications in model data entries that are used to more 

accurately predict field conditions. Model predicted values were within 2 dBA of 

those values measured in the field, demonstrating that the model predicted actual 

monitored conditions well. 

Modeling of Existing Conditions 

Noise levels for current (2004) conditions were modeled at sensitive receivers in 

the project area. This was done to determine where noise impacts currently exist 

and to establish the baseline from which a substantial increase in noise levels is 

determined. Traffic data necessary for modeling were obtained from several 

different sources. The primary source of information was the Traffic Report 

prepared for this project. The report provided traffic counts, speeds, peak hour, and 

vehicle classification information (numbers of trucks, cars, etc.) for most of the 

streets in the study area. The project route was broken into multiple segments 



4-50 

68 

73 

57 

55 

69 

56 

63 




within the model to accommodate areas where the roadway climbs and traffic 

volumes and speeds differed. Roadway geometry, topography, and receiver 

locations and elevations were established from MicroStation plan sets from project 

design engineers and PAG aerial photos and digital terrain model files. 

One hundred twenty-six representative properties throughout the study area were 

selected as model receiver locations (see Figures 4-4a-d). Residences and 

businesses within the study area were chosen as representative sensitive noise 

receivers and STAMINA was used to estimate the noise levels at these receiver 

locations under existing (2004) traffic and under predicted conditions (2030). The 

results of the analysis are presented in the table in Appendix C. Noise receivers 

were designed as NR# along the north side of Twin Peaks Road, RS# along the 

south side of Twin Peaks Road, I10F# in the area of I-10 and its frontage roads, or 

LVR# along Linda Vista Boulevard. 

Impacts 


The noise monitoring and modeling analyses suggested that the NAC are exceeded 

at a number of locations within the study area. Because traffic noise levels are 

dependent upon traffic volumes, and traffic volumes are predicted to increase in the 

area, noise levels would increase also. As a result additional properties in the project 

area would be impacted by traffic noise regardless of whether or not the project is 

constructed. According to the table in Appendix C, the entire area near I-10 (all 

receivers beginning I10F#) exceeds the NAC under current conditions. All 

modeled locations in this area are commercial land uses. Although one residential 

property exists within this area, this residence would be acquired by the proposed 

improvements; therefore, this residential site was not modeled. With the exception 

of this area near I-10, only one other receiver (LVR12) within the study area 

approached or exceeded the NAC for the year 2004. This receiver, located at the 

intersection of Linda Vista Boulevard and Manatee Drive is adjacent to Linda 

Vista Boulevard and substantially lower in elevation than the roadway. This 

residence (as opposed to most in the area) is not separated from the roadway by a 

wall. It is reasonable to assume that, with additional traffic growth, additional 

residences in this area would exceed the NAC. 


Temporary Impacts 

Construction noise differs from traffic noise in several ways: 

• Construction noise lasts only for the duration of the construction contract, 

and it is usually limited to daylight hours when most human activity 

occurs. 

• Construction activities generally are of a short-term nature, and depending 

on the nature of construction operations, it could last from seconds (e.g., a 

truck passing a receiver) to months (e.g., constructing a bridge). 



4-51 




Construction noise is intermittent and depends on the type of operation, location, 

and function of the equipment, and the equipment usage cycle. Traffic noise is 

more continuous after construction activities are completed. 

Permanent Impacts 

Predicted noise levels assuming completion of the preferred alternative may be 

found in the column labeled Modeled Future (2030) in the table in Appendix C. Of 

the 126 modeled receivers, 49 were predicted to experience noise levels that would 

require consideration of traffic noise abatement. The results of the modeling for 

the future condition are divided by area and discussed in the following sections. 

Twin Peaks Road (Receivers noted as NR# and RS#) 

As would be expected, adding a new segment of Twin Peaks Road to connect to 

I-10 increases traffic substantially through Continental Ranch and results in traffic 

moving through an area where no traffic exists currently. As a result of this 

increase in traffic and the new roadway, noise levels are predicted to increase 

along Twin Peaks Road. As shown in the table in Appendix C, the increase in 

traffic noise levels ranges from 6 dBA to 18 dBA. The areas of higher increases 

were those areas on the east side of Continental Ranch where no roadway exists 

currently (NR26-NR32A and RS27-RS30). 

Although STAMINA did not predict that traffic noise levels would approach or 

exceed the NAC (64 dBA or higher for the residences and other sensitive land uses 

in this area), substantial increases (15 dBA) in noise levels were predicted. These 

increases are predicted along the eastern border of Continental Ranch both north 

and south of Twin Peaks Road. 

Twin Peaks Road TI area (Receivers noted as I10F#) 

STAMINA predicted increases in traffic noise in this area as well. However, 

because traffic noise levels and traffic volumes are already high in this area, the 

predicted increases were much lower than along Twin Peaks Road. In this area 

traffic noise level increases ranged from 4 dBA to 5 dBA; however, all modeled 

receivers in this area approached or exceeded the NAC (69 dBA or higher for 

commercial properties). 

Linda Vista Boulevard (Receivers noted as LVR#) 

Although no improvements to Linda Vista Boulevard are proposed throughout the 

majority of the study area, the provision of a Twin Peaks Road TI, would result in 

increased traffic along Linda Vista Boulevard. To fully explore traffic noise 

impacts, traffic noise levels were modeled as far east as Thornydale Road (nearly 4 

miles east of the Twin Peaks Road TI). As a result of the increase in traffic, 

STAMINA predicted increases in traffic noise levels ranging from 2 dBA to 14 

dBA. Because of this wide range in values, these areas are discussed individually 

below. 



4-52 



NR1 

NR2 

NR3 

SILVERBELL ROAD 



NR31A-F 

NR29A-F 

NR32 

NR32A 

NR27 

NR27A 

NR27B NR26 

NR30 

NR26A 

NR7 NR8 NR13 NR14 

NR25 

NR30A 

NR6 

NR9 

NR11 

NR6 

NR12 

NR19 NR20 

NR10 

NR15 NR16 

NR18 

NR5 

RS5 

RS13 

RS7 RS9 

NR21 NR23 

RS6 

RS11 RS12 RS15 NR17 

NR24 

NR4 

RS14 

NR22 

SCHOOL3 RS8 

RS21 RS22 

RS10 

RS18 

SOCCER2 

SCHOOL4 

PARK17 

RS19 RS20 RS23 

TWIN PEAKS ROAD 

SAFEWAY 

RS30 

RS29 A-E 

4-53 

COACHLINE BLVD 

RS28 A-C 

PARK16 

RS27 

RS27A 

RS25 

RS26 

RS24 

NR28 

NR28A 

Noise 

Wall 

Figure 4-4a 

Noise Analysis 





IR1 

IR2 

IR3 

IR5 

IR4 

IR6 


IR7 

4-54 

IR8 

IR9 

IR10 

LV1 

IR11 



Figure 4-4b 




LV2 

LV3 




HARTMAN ROAD 

LV4 

Noise Wall 

LV5 

Noise Wall 

4-55 

LV6 LV7 

Noise Wall 

Noise Wall 

Noise Wall 

LV8 LV9 LV10 LV11 

BALD EAGLE DRIVE 

LV12 

LV17 

LV13LV14 LV15 LV16 

Noise Wall 

Figure 4-4c 







LV18 

LV19 

LV20 

LV21 

ARTHUR PACK GOLF COURSE 

4-56 

LV22 

LV23 LV24 

LV25 

LV26 

MOUNTAIN VIEW 

HIGH SCHOOL 

THORNYDALE ROAD 

Figure 4-4d 





The highest increases (14 dBA, 9 dBA, and 8 dBA at LVR1, LVR2, and LVR3, 

respectively) were the result of the relatively large increase in traffic volumes in 

the western segment of Linda Vista Boulevard. Currently, Linda Vista Boulevard 

in this area experiences total traffic volumes of approximately 60 vehicles per hour 

during the peak traffic period. With the completion of the Twin Peaks Road TI, 

traffic volumes in this area are expected to increase to approximately 980 vehicles 

per hour during the peak traffic period. The highest increase (14 dBA) was 

predicted at LVR1, a residence near the proposed new intersection of Twin Peaks 

Road/El Camino de Mañana/Linda Vista Boulevard. In addition to the increase in 

traffic volumes, the intersection would be relocated closer to this residence with 

the proposed improvements. 

As Linda Vista Boulevard moves east of Hartman Lane (represented by receivers 

LVR4-LVR26), single family housing is located near the roadway. Although noise 

levels were predicted to increase in this area, the increases were considerably less 

than those near the interstate. Noise levels along Linda Vista Boulevard east of 

Hartman Lane were predicted to increase by 2 dBA to 4 dBA. However, because 

of their proximity to the roadway, this relatively moderate increase in traffic noise 

levels caused a number of receivers (LVR7 – LVR10, LVR13-16, and LVR21) to 

approach or exceed the NAC. 

Mitigation 

Mitigation of Temporary Impacts 

Land uses in the project vicinity would be exposed to noise from construction 

activity under the preferred alternative. To minimize noise impacts from 

construction activities, the contractor shall control construction noise in 

accordance with Arizona Department of Transportation’s Standard Specifications 

for Road and Bridge Construction, Section 104.08 Prevention of Air and Noise 

Pollution (2000 Edition). This may include: 

• All exhaust systems on equipment would be in good working order. 

Properly designed engine enclosures and intake silencers would be used 

where appropriate. 

• Equipment would be maintained on a regular basis. 

• New equipment would be subject to new product emission standards. 

Stationary equipment would be located as far away from sensitive receivers 

as possible. 

Mitigation of Permanent Impacts 

Although 49 of the 126 receiver locations were predicted to meet criteria for 

consideration of noise mitigation in the 2030 build condition, 11 of these receivers 

(Receivers I10F1-I10F11) were commercial properties near I-10. It is ADOT’s 

policy that abatement is not considered reasonable for impacted businesses; 

therefore, noise mitigation for these 11 receivers was not considered. 



4-57 




Noise mitigation is implemented where the efforts are feasible, reasonable, 

effective and desired by the affected community. Feasibility of mitigation 

measures is determined by considering factors such as local access constraints, 

safety, community aesthetics and cohesion, visual impact, engineering constraints 

of height, drainage considerations, and other engineering requirements. 

Reasonableness is based on the size of the impacted area (number of structures, 

spatial distribution of structures, etc.), the predominant activities exercised within 

the area, practicality of construction, and cost. Effectiveness criteria are based on 

the amount of noise reduction provided by a barrier (at least 5 dBA) and the 

barriers ability to reduce noise levels below 64 dBA. All of these factors were 

considered in this analysis. The analysis is summarized in Table 4-8 and is 

discussed briefly below by the same areas that were discussed earlier. 

Twin Peaks Road (Receivers NR26-NR32A and RS27-RS30) 

The homes with predicted substantial increases in traffic noise were along the east 

side of Continental Ranch both north and south of Twin Peaks Road. Higher levels 

were predicted south of Twin Peaks Road because of the roadway’s slight 

curvature to the south. Mitigation was considered on both the north and south sides 

of Twin Peaks Road. It is important to note, however, that although these 

residences would experience a substantial increase in traffic noise levels according 

to ADOT criteria, the resultant noise levels are considerably below the levels at 

which mitigation is normally considered (64 dBA). 

A wall replacing the existing privacy wall along the east side of Continental Ranch 

north of Twin Peaks Road was only marginally effective at mitigating noise. 

According to STAMINA, a 20-foot tall wall along the back yards of these 

residences would reduce predicted noise levels by 5 dBA or greater at only 3 

residences (NR26, NR26A, and NR27). A 20-foot tall wall 309 feet in length 

would result in a 5 dBA reduction at 3 residences for an approximate total cost of 

$154,500. The cost per benefited receiver would be $51,500 which is greater than 

the $35,000 per benefited receiver recommended by ADOT. Because of the 

expense, the wall’s height, and the limited number of homes that would benefit 

from the wall, this wall would not be constructed. 

A wall replacing the existing privacy wall along the east side of Continental Ranch 

on the south side of Twin Peaks Road was effective at mitigating noise, but a very 

tall wall was necessary. A series of wall heights was examined in this area. Wall 

heights of ranging from 15 feet to 20 feet were examined. Because each of these 

walls protected varying numbers of homes, the most cost effective wall was 

selected. According to STAMINA, a 17-foot tall wall along the back yards of these 

residences would reduce predicted noise levels by 5 dBA or greater at 12 

residences (RS27, RS27A, RS28, RS28A, RS28B, RS28C, RS29, RS29A, RS29B, 

RS29C, RS29D, and RS29E). These results are presented in Table 4-8. A 17-foot 

tall wall 802 feet in length would result in a 5 dBA reduction at 12 residences for 

an approximate cost of $340,850. In addition, additional right of way would be 

acquired for the placement of the wall. Additional right of way costs in this area 



4-58 




are estimated to be $32,800 ($2 per square foot, 820 feet long and 20 feet wide); 

therefore, the cost per benefited receiver would be $31,138 which is less than the 

$35,000 per benefited receiver recommended by ADOT. Because this wall meets 

ADOT cost effectiveness criteria, this wall would be constructed. 

A slight adjustment to the existing privacy wall height along Twin Peaks Road 

was necessary. A segment of privacy wall along the south side of Twin Peaks 

Road as it approaches the connection with the proposed Twin Peaks Road 

extension is shorter than surrounding walls. Although other privacy walls in the 

area are effective at mitigating traffic noise with a 6.5-foot height, a short segment 

(111 feet in length) of 4.5-foot wall results in higher noise levels for RS25 and 

RS26. Increasing the height of this wall from 4.5 feet to 6.5 feet to match the 

surrounding walls would cost approximately $14,430 (to completely reconstruct 

the wall) is effective at reducing traffic noise levels at these two receiver locations 

by 5 dBA, and would result in a cost per benefited receiver of $7,215. This wall 

would be constructed. 

Although noise walls are the most common method of traffic noise mitigation, 

other methods were considered for reducing noise exposure to residents along 

Twin Peaks Road. One of the reasons traffic noise levels are relatively high along 

Twin Peaks Road is the existing roadway surface. The existing surface of Twin 

Peaks Road through Continental Ranch is in fair to poor condition. The pavement 

shows signs of low to medium severity deterioration, rutting, and various types of 

cracking. The Town of Marana proposes to resurface Twin Peaks Road west to 

Silverbell Road with RAC which would improve drivability of the roadway and 

decrease the noise generation from the tire-pavement interface. Although the FHWA 

would not participate in the funding of roadway resurfacing with RAC, the Town of 

Marana would fund this overlay. 

Linda Vista Boulevard (Receivers LVR1, LVR5, LVR7 – LVR10, LVR13-16, and 

LVR21) 

Receiver LVR1 – The greatest increase (14 dBA) and the highest noise level (67 

dBA) in this area was predicted at LVR1, which exists near the proposed 

intersection of Twin Peaks Road/El Camino de Mañana/Linda Vista Boulevard. 

Although noise levels at this residence were predicted to approach or exceed the 

NAC for residential land uses, this residence would be displaced by the proposed 

improvements; therefore, mitigation for this receiver was not considered. 

Receiver LVR5 – Traffic noise levels at receiver LVR5 (66 dBA) were predicted to 

exceed ADOT’s noise abatement criteria. This residence is a single isolated 

residence widely separated from neighboring properties on the north side of Linda 

Vista Boulevard. ADOT’s noise policy does not consider mitigation of receivers 

set apart from other receivers reasonable; therefore, this wall would not be 

constructed. 

Receiver LVR7 – Traffic noise levels at receiver LVR7 (65 dBA) were predicted to 

exceed ADOT’s noise abatement criteria. This receiver, which sits on the south 

side of Linda Vista Boulevard, is a newly constructed residence with a solid 



4-59 




concrete block wall along Linda Vista Boulevard. To preserve views of the Santa 

Catalina Mountains to the east, the residence’s eastern wall is constructed of 

wrought iron. To mitigate traffic noise, a solid wall along the eastern side of the 

property would be required. Because the home was constructed to preserve views 

to the east, it is assumed that construction of a solid wall in this area would be 

unacceptable to the property owner. In addition, the construction of a noise 

mitigation wall would protect only this single isolated residence, which is not 

considered reasonable by ADOT’s noise policy. For these reasons, this wall would 

not be constructed; however, this decision would be discussed during the public 

hearing for this project and during subsequent property owner meetings. 

Receiver LVR8 – This receiver, on the southwest corner of Linda Vista Boulevard 

and Albatross Drive, is predicted to experience traffic noise levels of 65 dBA. 

According to STAMINA, the residence south of LVR8 was predicted to exceed 

the NAC also; therefore, mitigation for these two residences was considered. A 

reduction in traffic noise levels of 5 dBA was produced by a wall 256 feet in 

length and 10 feet in height along Linda Vista Boulevard. This wall was estimated 

to cost $51,200 and protect two residences. The cost per benefited receiver is 

$25,600; therefore, this wall would be constructed. 

Receivers LVR9 – LVR10 – These receivers, from the southeast corner of Linda 

Vista Boulevard and Albatross Drive to the southwest corner of Linda Vista 

Boulevard and Bald Eagle Drive, are predicted to experience traffic noise levels of 

65 and 67 dBA, respectively. In addition to LVR9 and LVR10, an additional 6 

residences would experience noise levels in excess of the NAC in this area. These 

residences would be protected by a wall that begins 48 feet south of Linda Vista 

Boulevard, moves north to Linda Vista Boulevard and then turns to the east for 

500 feet. The 48-foot length would be 11.5 feet in height and the 500-foot length 

would be 12 feet in height. The approximate overall cost for the wall would be 

$131,040. The wall would protect only 7 of the 8 receivers in this area. LVR10 

represents the clubhouse and community swimming pool for this subdivision, 

which currently has a wrought iron fence on the east side to allow views of the 

mountains. To reduce noise substantially at this location, the wall would be 

required to wrap to the south in this area, which would result in blocking the 

mountain views; therefore, extending the wall to the south would not occur; 

however, this decision would be discussed during the public hearing for this 

project and during subsequent property owner meetings. All homes in the area 

would be benefited by the proposed wall. The cost per benefited receiver for this 

wall would be $18,720; therefore, this wall would be constructed. 

Receivers LVR11 – LVR12 – These receivers, from the southeast corner of Linda 

Vista Boulevard and Bald Eagle Drive to the southwest corner of Linda Vista 

Boulevard and Manatee Drive, are predicted to experience traffic noise levels of 

67 and 69 dBA, respectively. In addition to LVR11 and LVR12, an additional 4 

residences experience noise levels in excess of the NAC in this area. Although 

several of these residences have an existing 6-foot wall that parallels Linda Vista 

Boulevard, these homes are several feet lower in elevation than the roadway. All 



4-60 




of these homes may be protected by a wall between Bald Eagle Drive and Manatee 

Drive that would be 773 feet in length and 5.5 feet in height. The approximate 

overall cost for the wall would be $85,030. The wall would protect 6 receivers at a 

cost per benefited receiver of $14,172; therefore, this wall would be constructed. 

Receiver LVR13 – This receiver is located in the southeast corner of Linda Vista 

Boulevard and Manatee Drive and is predicted to experience traffic noise levels of 

64 dBA. According to STAMINA, the residence immediately south of LVR13 

(LVR13A) does not approach the NAC. To mitigate noise, a wall that begins 51 

feet south of Linda Vista Boulevard, moves north to Linda Vista Boulevard and 

then turns to the east for 101 feet was examined. The 51-foot length of wall would 

begin at 9.5 feet in height and increase to 12.5 feet in height as it reaches Linda 

Vista Boulevard. The entire 101-foot length would be 12.5 feet in height. The 

approximate overall cost for this wall would be $36,480 and only receiver LVR13 

would receive a 5 dBA benefit; therefore, this wall would not be constructed. 

Receivers LVR14 – LVR15 – These receivers, from the drainage channel east of 

LVR13 to the southwest corner of Linda Vista Boulevard and Waterbuck Drive, 

are predicted to both experience traffic noise levels of 64 dBA. In addition to 

LVR14 and LVR15, an additional 3 residences experience noise levels in excess of 

the NAC in this area. All of these homes may be protected by a wall between the 

drainage channel and Waterbuck Drive that would be 463 feet in length which 

connects to the existing walls on the both ends to the south. The wall would be 10 

feet in height and would be constructed at an approximate cost of $92,600. The 

wall would protect 5 receivers at a cost per benefited receiver of $18,520; 

therefore, this wall would be constructed. 

Receiver LVR16 – This receiver is located on the southeast corner of Linda Vista 

Boulevard and Waterbuck Drive and is predicted to experience traffic noise levels 

of 64 dBA. According to STAMINA, the residence immediately south of LVR16 

(LVR16A) does not approach the NAC. A 12.5-foot wall that begins 60 feet south 

of Linda Vista Boulevard, moves north to Linda Vista Boulevard, turns to the east 

for 150 feet, then turns south for an additional 13 feet to tie to the existing fence 

along the drainage channel to the east of LVR16 would be required. The 

approximate cost for this wall would be $55,750 and only LVR16 would be 

benefited; therefore, this wall this wall would not be constructed. 

Receiver LVR21 – This receiver is located on the Arthur Pack golf course west of 

Mountain View High School on the south side of Linda Vista Boulevard. Noise 

levels are predicted to reach 67 dBA in this area because of the proximity of the 

golf course to the roadway. However, mitigation was not considered for this 

receiver because golfers are exposed to traffic noise for relatively short periods of 

time on the course and walls would impose a visual restriction on views to the 

north and east from the golf course. 



4-61 



Wall to 

Protect 

Rec. ID 


Total 

Units 

(Benefited) 

Table 4-8. Noise Mitigation Evaluation Summary 

2030 

Unmiti 

-gated 

Noise 

Level 

(dBA) 

2030 

Mitigated 

Noise 

Level 

(dBA) 

Barrier 

Insertion 

Loss 

(dBA) 

Barrier Dimensions Barrier Segment Costs 

Approximate 

Length 

(feet) 

Height 

(feet) 

Total 

Cost 

($20-25 

/square 

foot) 

Cost per 

Benefited 

Receiver 

NR26 3 60 54 6 309 20 $154,500 $51,500 

NR26A 59 53 6 

NR27 58 53 5 

RS27 12 60 55 5 802 17 $340,850 $28,404 

RS27A 58 53 5 

RS28 58 52 6 

RS28A 56 51 5 

RS28B 56 51 5 

RS28C 56 51 5 

RS29 55 50 5 

RS29A 55 50 5 

RS29B 54 49 5 

RS29C 55 49 6 

RS29D 55 48 7 

RS29E 53 48 5 

RS30 52 48 4 

RS25 2 61 56 5 111 6.5 $14,430 $7,215 

RS26 64 59 5 

LVR1 1 67 Single isolated receiver – no barrier recommended 



LVR8 2 65 60 5 256 10 $51,200 $25,600 

LVR9 7 65 60 5 48 11.5 

LVR10 67 65 2 500 12 $131,040 $18,720 

LVR11 6 67 62 5 773 5.5 $85,030 $14,172 

LVR12 69 62 7 




4-62 



Wall to 

Protect 

Rec. ID 


Total 

Units 

(Benefited) 

Table 4-8. Noise Mitigation Evaluation Summary 

2030 

Unmiti 

-gated 

Noise 

Level 

(dBA) 

2030 

Mitigated 

Noise 

Level 

(dBA) 

Barrier 

Insertion 

Loss 

(dBA) 

Barrier Dimensions Barrier Segment Costs 

Approximate 

Length 

(feet) 

Height 

(feet) 

Total 

Cost 

($20-25 

/square 

foot) 

Cost per 

Benefited 

Receiver 

LVR14 5 64 59 5 463 10 $92,600 $18,520 

LVR15 64 59 5 



Note: Recommended walls are indicated by bolding 

Conclusion 

Figures 4-4a through 4-4d illustrate locations where walls would be constructed to 

protect impacted receivers. Although 49 of the 126 receiver locations were 

predicted to meet criteria for consideration of noise mitigation in the 2030 build 

condition, 11 of these locations were commercial properties; therefore, noise 

mitigation for these 11 properties was not considered. Noise barrier walls were 

analyzed in 13 locations to protect impacted residences. Of these locations, 6 walls 

would protect single isolated residences and would not be constructed per ADOT 

policy. One wall would protect three residences at a cost of $51,500 per residence; 

therefore, this wall was determined to not meet ADOT’s cost per benefited 

receiver criterion and was not recommended. Six locations were recommended for 

the construction of noise abatement walls. These six walls would protect a total of 

34 residences and would meet ADOT’s cost per benefited receiver criterion. 

Although the Town intends to construct these walls as described above, the final 

decision would be made following the public hearing process and discussions with 

affected property owners. The design parameters of these walls would be 

determined during final project design. 

In addition to mitigation using noise walls, resurfacing Twin Peaks Road west to 

Silverbell Road with RAC is proposed also. This treatment would improve 

drivability of the roadway and decrease the noise generation from the tire-pavement 

interface. Although the FHWA would not participate in the funding of roadway 

resurfacing with RAC, the Town of Marana would fund this overlay. 

Hazardous Materials 

It is important to locate sites of soil or groundwater contamination before 

performing construction activities. These contaminated properties could pose a 

physical danger to construction crews or be liabilities if construction causes 

contamination to migrate. To determine the potential of soil or groundwater 



4-63 




contamination in the project area, URS conducted a PISA of properties that may 

be affected by the proposed construction. The purpose of the PISA was to perform 

a screening-level assessment to identify potential conditions associated with 

hazardous materials associated with individual properties within the Study Area, 

and to identify those parcels requiring more detailed investigation. The assessment 

was based on the findings of a limited site reconnaissance, a review of aerial 

photographs, a review of Tucson City business directories, a review of historical 

ADOT R/W drawings, a review of federal and state environmental records, a 

review of Tucson Water As-Built Plans, and ADWR water well records. 

The complete results of the investigations are presented in the document Interstate 

10 Traffic Interchange at Twin Peaks/Linda Vista Preliminary Initial Site 

Assessment, dated January 14, 2004. Readers are referred to this report for the 

detailed findings; however, the results are summarized below. 


Based on the findings of this assessment, the study area parcels were identified as 

High, Medium or Low Priority for conducting further hazardous materials 

investigation work. Eleven parcels were identified as high priority. A high priority 

rating was assigned to parcels with a history of commercial or industrial use or that 

were identified in the environmental agency databases. The designation of a parcel 

as a high priority site did not mean that known hazards were present on the parcel. 

All sites designated as high priority were located in the commercial area on the 

west side of I-10. The 11 sites were designated high priority because of the 

following existing or historic land uses and the hazardous materials they may have 

used, handled, stored, or disposed: 

• Roofing company and manufacture of steel products – solvents and 

processing chemicals 

• Manufacture of pre-cast or molded products – solvents, petroleum 

• Auto repair – petroleum and solvents 

• Mechanical equipment maintenance and storage, plant nursery – pesticides, 

solvents, petroleum 

• Heavy equipment sales and rentals – petroleum 

• Auto salvage yard, recorded leaking underground storage tanks (LUST) – 

petroleum 

• Heavy equipment sales and rentals, equipment maintenance – petroleum 

and solvents 

• Adjacent to site with reported fuel spills, fuel storage – petroleum 

• Site of reported fuel spills, fuel storage – petroleum 

• Unregistered historic underground storage tanks (UST), heavy equipment 

usage – petroleum 



4-64 




• Equipment rentals, landscaping, fuel storage – petroleum 

Four parcels were identified as medium priority. These parcels were identified as 

having a lesser potential for hazards due to unknown historical usage or 

indications of dumping. Nineteen parcels were identified as low priority sites. Low 

priority parcels are considered to have a low likelihood of encountering hazardous 

materials. 

According to Tucson Water, most of the larger water supply lines in the project 

area were cement asbestos. Twelve-inch cement asbestos water lines served the 

commercial parcels on the west side of I-10 along the western property lines. A 

12-inch cement asbestos water supply line brought water into Continental Ranch 

approximately along the centerline of Twin Peaks Road. There were numerous 

private wells in the area as well. According to the ADWR, at least 21 registered 

wells were located near the study area; however, there may also be other, 

unrecorded wells within the area. All properties in the commercial area on the west 

side of I-10 within the project area disposed of liquid waste in individual septic 

tanks. 

Impacts 


Because existing soils would remain undisturbed, no impacts from hazardous 

materials would result from the no build alternative. 


The preferred alternative would acquire additional R/W from all properties in the 

commercial area on the west side of I-10 within the project area. As a result, all 

properties noted as high or medium priority in the PISA for this project would be 

affected by the preferred alternative. In addition to R/W acquisition, soils on several 

of the properties would be disturbed by the construction of the preferred alternative; 

therefore, the possibility of encountering hazardous materials would be increased 

from these activities. Subsurface ground disturbance during construction could 

affect also asbestos-containing water supply lines, private wells, and individual 

septic tanks located on these properties. 

Mitigation 

Before construction, the Town of Marana would conduct detailed Phase I Site 

Assessments to assess site-specific potential for hazardous materials issues on 

parcels rated as high and medium priority. Additional investigation may include, 

but is not limited to, additional site reconnaissance and interviews with current and 

historical property owners. If parcels to be acquired involve structures, following 

the acquisition of the structure but prior to its demolition, the structures would be 

assessed for asbestos, lead-based paint, and other hazardous materials in 

accordance with State and Federal regulations. 

The Town of Marana would review sellers’ disclosure statements and title records 

of acquired properties for indications of hazardous materials usage and/or disposal 



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activities. Disclosure statements demonstrating affirmative or unknown responses 

for such activities would be subject to Phase I Site Assessments activities. 

The Town of Marana would determine the location of unrecorded wells on 

potential acquisition properties prior to final roadway design and R/W acquisition. 

If wells are identified on the parcels to be acquired, the wells would be abandoned 

in accordance with the requirements of the ADWR. 

If relocation of asbestos-containing water lines is required, the contractor would 

handle, transport, and dispose of the material in accordance with approved federal, 

state, and county asbestos handling procedures. This would include appropriate 

precautions to ensure that employees are not exposed to airborne asbestos fibers and 

that fibers are not released into the atmosphere. 

Any construction project has the potential to discover new and previously 

undocumented cases of contamination. According to Arizona Department of 


Section 107 Legal Relations and Responsibility to Public (2000 Edition) (Stored 

Specification 107HAZMT, 01/15/93), if previously unidentified or suspect 

hazardous materials are encountered during construction, work would stop at that 

location and the Town of Marana Engineer would be contacted to arrange for 

proper treatment of those materials. Such locations would be investigated and 

proper action implemented prior to the continuation of work in that location. 

Conclusion 

Based upon the information contained within the PISA, additional R/W would be 

acquired from potentially contaminated properties, contaminated soils or 

groundwater may be encountered during project construction, and contaminated 

properties are possible within the project area that could pose a physical danger to 

construction crews. Because of these findings, a commitment was made to conduct 

additional investigations of high and medium priority sites prior to construction 

activities and to investigate any new cases of contamination that may be encountered 

during construction activities. 

Cultural Resources 

To ensure compliance with the National Historic Preservation Act and to prevent 

the disturbance of historic and/or cultural resources within the study area, a records 

search and a field survey were conducted to identify these resources. The results of 

the search and survey are summarized below. 

The AZSITE Cultural Resources Inventory was reviewed to identify information 

about prior studies and previously recorded resources in the project vicinity. 

AZSITE is a geographic information system database that includes records of the 

Arizona State Museum (ASM), Arizona State University, Museum of Northern 

Arizona, Bureau of Land Management, and State Historic Preservation Office 

(SHPO), including properties listed in the National Register of Historic Places 



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(NRHP). Reports of major prior studies were reviewed also, including a recently 

completed overview prepared for the TRDN Project, which overlaps most of the 

records search area. The records search, which encompassed approximately 10.3square-miles, 

identified information about 73 prior studies within the search area. 

Prior surveys were extensive and encompassed almost 90 percent of the record 

search area (9.25 square miles). 

The intensive pedestrian archaeological survey encompassed approximately 144 

acres of privately owned land. Observational transects at intervals of 20 meters or 

less were walked. The survey area was easily traversed and vegetation was sparse, 

which facilitated the survey. Approximately 140 acres was field surveyed for 

archaeological resources. Approximately 107 acres was previously surveyed. 

Thirteen acres within the channelized bed of the Santa Cruz River were not 

surveyed and another 5 acres were not surveyed because right-of-entry had not 

been acquired from the property owners. The 5 acres within the discontiguous Safe 

Routes to School corridor are within areas that were previously surveyed and data 

recovery studies had been conducted prior to construction of the modern 

residential development that now covers the area. This area was not resurveyed. 

In addition to the pedestrian survey, a historic building survey was completed for 

all existing properties within the project area. Potential historic-age buildings and 

structures were identified from County Assessor records and then field verified. 

All 22 parcels on the southwestern side of I-10 were surveyed for historic 

buildings and structures. There were no buildings on the northeastern side of I-10. 

The PISA prepared for this project was reviewed because that study had examined 

aerial photographs dating between 1960 and 2000, maps dating from the late 1960s 

to the mid-1970s, and ADOT as-built plans from 1961. Properties constructed 

prior to 1960 were field inventoried. These inventories collected information about 

location, property type, historic and present use, construction materials, 

architectural style, condition, modifications or additions, and other integrity 

considerations. The information was used to complete Arizona Historic Property 

Inventory forms. 

Identification of Cultural Resources 

Archeological Sites - Previously Recorded 

The 73 previous surveys identified 49 archaeological and historical resources 

within the records search area. Thirty-one of these sites reflected the prehistoric 

occupation of the region, 15 were from the historic era, and three sites had both 

prehistoric and historic components. 

The surveys indicated that 14 of the 31 recorded prehistoric sites were habitation 

sites, 10 were artifact scatters without features, and the other 7 were artifact 

scatters with no identified features. A high percentage of sites appeared to be 

villages, which probably reflected the location adjacent to the Santa Cruz River. 

One site dated to the Archaic era, and the others to the Hohokam period. Four 

village sites were described as mostly or completely destroyed. Data recovery 



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studies were conducted at two of those before residential developments were 

constructed. Another appears to have been destroyed by erosion before it was 

recorded, and a sand and gravel quarry operation destroyed another. 

Numerous features were recorded at the seven artifact scatters with features. These 

included, rock shelters, bedrock mortars, check dams, rock piles, a canal, hearths, 

and roasting pits. One site dated to the Archaic era, and the others were Hohokam. 

Two sites were characterized as artifact scatters without features and were 

destroyed after they were recorded and another could not be found when a 

subsequent survey tried to relocate the site. Eight of the 15 historic-era sites were 

habitations or sites with remnants of other types of buildings. Three of these were 

homesteads. 

Four of the historic sites were related to transportation. These included the Tucson- 

Casa Grande Highway (State Route (SR) 84), and its predecessor, the Red Rock 

Road. Another was the current UPRR, which was constructed in 1880. The fourth 

is the Juan Bautista de Anza National Historic Trail, which is one of only 19 

National Historic Trails designated by Congress. The trail corridor was identified 

on the basis of written documents, and no physical evidence of the de Anza 

expedition have been found in the record search area. 

Of the three sites with both prehistoric and historic components, data recovery was 

conducted at one site before it was destroyed by a residential development. 

Another had remnants of a historic house with a scatter of prehistoric artifacts. The 

third site was a scatter of both prehistoric and historic artifacts. 

Archeological Sites – Field Survey 

Twelve of the previously recorded archaeological and historical resources 

identified by the records search were mapped within the alternatives area, and each 

of these was re-evaluated during the field survey. The current surveys located three 

additional cultural sites, one historic-age building, and two historic age wells that 

were previously unrecorded within the project area. Each of these resources are 

described below. The ASM site number follows the site name. 

Tucson-Casa Grande Highway (SR 84) AZ AA:2:118(ASM) 

Different segments of SR 84 have been recorded and designated with various 

numbers in the Arizona State Museum survey system. The segment of the highway 

within the alternatives analysis area was converted to the northwest-bound 

frontage road of I-10 when I-10 was constructed. The historic highway remains in 

use as a frontage road and is well maintained. During the field surveys for this 

project, two concrete box culverts were noted along the highway within the 

alternatives analysis area. Each has a survey benchmark medallion dated 1930. 

Stewart Brickyard Site AZ AA:12:51(ASM) 

The Stewart Brickyard site was recorded in 1955 and was described as a scatter of 

Hohokam pottery sherds that had been progressively destroyed by construction of 

the Southern Pacific Railroad, Casa Grande Highway (SR 84), and the Southern 



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Pacific Pipeline. Subsequently the site was characterized as a large Hohokam 

village. Even though the site is on the opposite side of the Santa Cruz River, it may 

have been part of the community centered around Los Morteros. During the field 

survey conducted for this project, it was noted that a sand and gravel operation that 

was redeveloped as the Pines Golf Club at Marana had destroyed the site south of 

the Arizona Block and Brick Company parcel. During the course of recording the 

Arizona Block and Brick Company building, the crew inspected the parcel. No 

artifacts or archaeological features were noted, but more deeply buried 

archaeological deposits could remain. 

Scatter Of Hohokam Pottery Sherds AZ AA:12:52(ASM) 

This site was first recorded in 1958 and described as a scatter of Hohokam pottery 

sherds; however, the site was noted as destroyed by construction of the Southern 

Pacific Railroad, Casa Grande Highway (State Highway 84), and the Southern 

Pacific Pipeline in 1958. I-10 was subsequently constructed in this corridor as 

well. 

Disturbed Scatter Of Hohokam Pottery Sherds AZ AA:12:146(ASM) 

This site was discovered in 1981 and subsequent testing and data recovery 

identified 23 features including pit houses, small pits, roasting pits, rock 

concentrations, and a secondary cremation. The site was interpreted as a middle 

Sedentary period habitation locus associated with the community centered on Los 

Morteros. The site was described as no longer existing prior to construction of the 

residential development that covers the former site location. 

Extensive And Dense Scatter Of Hohokam Pottery Sherds And Flaked Stone AZ 

AA:12:226(ASM) 

This site was discovered in the 1980s by the North Tucson Basin Survey, and 

described as an extensive and sometimes dense scatter of Hohokam pottery sherds 

and flaked stone, along with fire-cracked rock and areas of ash staining. In 2003, 

archaeological monitoring of geotechnical testing near the site as part of the I-10 

widening project discovered only a few artifacts. During the field surveys for this 

project, it was noted that the scatter extended farther west than originally mapped, 

and site boundaries were expanded approximately 3 acres to include the entire 

distribution of surface artifacts, increasing the total site area to approximately 24.2 

acres. 

Large Artifact Scatter And Possible Hohokam Pit House Village AZ 

AA:12:227(ASM) 

This site was discovered in the 1980s by the North Tucson Basin Survey and a 

recent survey inspected the site and reported finding approximately 50 artifacts on 

the site surface. Test excavations were recommended to determine if buried 

cultural deposits were present and evaluate the National Register eligibility of the 

site. During the field surveys for this project, a sample of surface artifacts were 

counted and a high density of artifacts at the site was suggested. 



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Circa 1900-1930s Adobe House, A Trash Pit, And Multiple Trash Scatters AZ 

AA:12:350(ASM) 

This site was discovered in the 1980s by the North Tucson Basin Survey. A 2003 

study inspected the site and found a 27-foot-square foundation of shaped cobbles 

protruding from a mound of melted adobe about 2 feet high. The trash pit, about 

10 feet wide, 12 feet long, and 3 feet deep, also was found, as well as an extensive 

artifact scatter. The surface assemblage was estimated to consist of approximately 

500 glass shards, 200 metal items, and 50 fragments of broken ceramic tableware. 

The site was recommended as eligible for the National Register under Criterion D 

for its potential to yield information about rural settlement in the Tucson Basin 

during the first part of the twentieth century. 

Antonio Alvarez Homestead AZ AA:12:370(ASM) 

This site was discovered in the 1980s by the North Tucson Basin Survey. Based on 

an 1896 survey, the site was identified as the homestead of Antonio Alvarez. The 

site was described as having remnants of an adobe building, a watering trough, a 

well, a rock pile, and a trash scatter. These features were on the east side of the 

Southern Pacific Railroad and the house was on the west side. This site was 

destroyed shortly after recording. Testing within the railroad R/W in 1992 failed to 

find any subsurface remains and at least four subsequent surveys found no 

evidence of the site. During the field surveys for this project, no trace of the site 

was found. 

Small Scatter Of Seven Pottery Sherds, And 5 Pieces Of Flaked Stone AZ 

AA:12:912(ASM) 

This site was recorded in 2002 and the recorders recommended that the site be 

considered eligible for the NRHP because of the potential for buried 

archaeological deposits that could yield important information. During the field 

surveys for this project, only five plain ware pottery sherds and a single piece of 

flaked stone were found. 

Red Rock Road AZ AA:12:952(ASM) 

Red Rock Road was recorded in 2003 and identified this unimproved dirt road as 

the principal route between Tucson and Red Rock prior to construction of the 

Tucson-Casa Grande Highway (SR 84) in the 1920s. This road currently is used to 

access ranch lands and a Yaqui cemetery. Small scatters of historic artifacts were 

noted along the road, and the road was recommended it be considered eligible for 

the National Register under Criterion A. During the field surveys for this project, 

the southern end of the road at its junction with El Camino De Mañana was 

inspected. 

Concrete Weir and Earthen Ditch AZ AA:12:955(ASM) 

This site, a concrete weir associated with an earthen ditch, was recorded during the 

field surveys for this project. The site consisted of a concrete weir with a central 

rectangular notch approximately 22 feet long, 8 inches wide, and a maximum of 



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approximately 3 feet above the ground at center. The central notch is 5.5 feet wide, 

1.5 feet deep, and has a narrow groove that perhaps once held a gate. The second 

feature at the site was a shallow swale aligned perpendicularly to the center of the 

weir. The swale was approximately 30 feet wide, 2 to 3 feet deep, with low berms 

on both sides. The swale could be traced for approximately 150 feet to the northnorthwest 

and about 550 feet to the south. 

The age of the structure is unknown, but the appearance of the concrete suggested 

it dated from the first or second quarter of the twentieth century. The swale was a 

silted-in ditch that once carried water, and the weir controlled the flow. The ditch 

generally paralleled local contours, but sediment indicated that water flowed to the 

north. The North Tucson Basin Survey noted similar ditches to the southeast, and 

hypothesized that they were dug to collect rainfall runoff and channel it to bean 

fields on the Santa Cruz River floodplain to the west; however, the ditch at this site 

does not seem to be oriented to delivering water to the floodplain. The ditch might 

have been built to control sheet flow erosion, but the weir does not resemble any 

recorded structures built by the Civilian Conservation Corps. 

Historic Trash Scatter AZ AA:12:956(ASM) 

This site was a sparse scatter of historic cans and broken glass that was recorded 

during the field surveys for this project. The irregularly shaped site was 

approximately 70 feet wide and 160 feet long. A count of surface artifacts tallied 

134 items, but they appear to represent only 30 cans, three glass bottles, and a 

crown cap. The artifacts represented food cans, milk containers, key-opened 

sardine cans, one tea container, one possible ketchup container, and a patent 

medicine bottle. The assemblage is quite small and may have been a secondary 

dump of household debris, or possibly the remains of a short-term camp. 

The most chronologically diagnostic artifacts were hole-in-top (matchstick filler) 

milk cans, which suggested a date in the early 1920s. Although the sale of patent 

medicine was outlawed by the Pure Food and Drug Act of 1906, patent medicines 

continued to be sold into the 1920s because of loopholes in the law and the 

relatively minor fines imposed for violations. 

Cortaro-Marana Irrigation District Canal AZ AA:12:957(ASM) 

The CMID Canal and two related wells were recorded during the field surveys for 

this project. The recorded segment of the irrigation canal site was approximately 3 

miles long. The canal was concrete lined and approximately 10 feet wide and 3 

feet deep. Thirteen features were recorded along the length of this canal. Seven of 

the features were inverted siphons that carried the canal beneath washes. One 

siphon was associated with a double culvert. Five of the features were simple slab 

bridges that allowed vehicle access from the I-10 westbound frontage road 

(Tucson-Casa Grande Highway) across the canal. One feature was a set of gates to 

control flow to lateral canals. 

Two historic-age wells associated with the CMID also were identified. Well 16 

was a fenced well site that may have been drilled as early as 1919 and Well 22 was 



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drilled in 1948. The above ground pumps and facilities of both wells appeared to 

be modern. 

The Town of Marana was originally established in 1890 as a Southern Pacific 

Railroad station. In 1919, Valley Farms constructed a canal, dug wells, and 

installed an oil engine power plant. Components of these irrigation systems were 

eventually incorporated into the current CMID. In 1965, the CMID and the 

Cortaro Water Users Association took over the administration of the irrigation 

district. The main canal and many of the laterals were lined with concrete in the 

1940s and 1950s, and gunite lining was applied in the mid-1970s. 

Southern Pacific Railroad (currently the Union Pacific Railroad) AZ 

EE:3:53(ASM) 

The Southern Pacific Railroad main line across the entire state was determined 

eligible for the NRHP by the SHPO. The rail bed, ties, tracks, two trestle bridges, 

and a utility line were recorded along the railroad within the project area. The 

UPRR continues to operate and maintain the line as a modern railroad. The track 

was upgraded over the years and few historic materials remain intact, but much of 

the line followed the original alignment constructed in 1880 through the project 

area. 

Juan Bautista de Anza National Historic Trail (No Site Number Assigned) 

The Juan Bautista de Anza National Historic Trail is a nationally significant 

resource. However, identification of the trail corridor was based on historical 

documents, and no physical evidence of the de Anza expedition remains. 

Isolated Occurrences (No Site Number Assigned) 

Nine isolated occurrences (IO) were discovered during the field survey for this 

project. Eight of these consisted of one to four pieces of pottery, mostly plain 

wares. The other IO was a white chert biface. 

Historic Structures 

Western Meat Packing Company (No Site Number Assigned) 

The only historic-age building identified within the alternatives analysis area was 

Western Meat Packing Company (Stewart Block and Brick) located at 9311 N. 

Casa Grande Highway, which was recorded during the survey for this project. 

County Assessor records indicate that the building was constructed in 1957, but 

design elements of the building, including detailing on the doors and window 

surrounds on the front of the building, indicated that the building may have been 

built as early as the mid-1940s. The Western Meat Packing Company was one of 

earliest commercial structures to be built along this portion of Casa Grande 

Highway. By 1980, the livestock pens were removed and the property was 

converted to a concrete block manufacturing company. A 2000 aerial photograph 

documented additions to the original building. 



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Traditional Cultural Places 

Although not formally designated as a Traditional Cultural Place, a Pascua Yaqui 

cemetery represents a highly sensitive historic resource near the project area. 

When first recorded, the site was characterized as a Hispanic cemetery, but 

subsequent research indicated the cemetery was established by residents of Yoem 

Pueblo, a Yaqui community in Marana. 

Eligibility Determination 

Cultural resources within the project area were evaluated using criteria for listing 

on the NRHP and the Arizona Register of Historic Properties. To be eligible for 

the NRHP, properties ordinarily must be at least 50 years old, and must be 

important in American history, architecture, archaeology, engineering, or culture. 

They must possess integrity of location, design, setting, materials, workmanship, 

feeling, or association. In addition, properties must meet at least one of the 

following four criteria: 

Criterion A: are associated with events that have made a significant 

contribution to the broad pattern of our history 

Criterion B: are associated with the lives of persons significant in our 

past 

Criterion C: embody the distinctive characteristics of a type, period, or 

method of construction, or that represent the work of a 

master, or possess high artistic values, or that represent a 

significant distinguishable entity whose components may 

lack individual distinction 

Criterion D: have yielded or may likely yield information important in 

prehistory or history. 

Previously recorded archaeological and historical sites were revisited as part of 

this survey and the sites were reviewed for eligibility for inclusion in the NRHP. 

The sites recorded initially during the field survey for this project were also 

analyzed for eligibility. Each of the sites is presented below in Table 4-9. Four 

sites, Stewart Brickyard Site - AZ AA:12:51(ASM), Scatter Of Hohokam Pottery 

Sherds - AZ AA:12:52(ASM), Disturbed Scatter Of Hohokam Pottery Sherds - AZ 

AA:12:146(ASM), and Antonio Alvarez Homestead AZ AA:12:370(ASM) were 

found to either be destroyed and no trace of the sites remained or unlikely to yield 

important information about the area and its history; therefore, these sites are not 

discussed further. 

No further consideration of cultural resources is recommended unless buried 

archaeological resources or human remains are unexpectedly encountered during 

project implementation. If buried artifacts, archaeological features, or human 

remains are encountered unexpectedly, they would be protected in place and 

reported to the Director of the ASM in compliance with the Arizona Antiquities 

Act. 



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Table 4-9. NRHP Eligibility Recommendations of Recorded Sites 

ASM Site # Description 

Eligible to 

NRHP? (Y/N) 

Eligibility Criterion 

AZ AA:2:118 SR 84 Y D 

AZ AA:12:226 Hohokam Pottery Y D 

AZ AA:12:227 Possible Hohokam Pit 

House Village 

Y D 

AZ AA:12:350 Adobe House Y D 

AZ AA:12:912 Pottery/Stone Scatter N N/A 

AZ AA:12:952 Red Rock Road Y D 

AZ AA:12:955 Concrete Weir Y D 

AZ AA:12:956 Historic Trash Scatter N N/A 

AZ AA:12:957 CMID Canal N N/A 

AZ EE:3:53 UPRR Y A 

None assigned Juan Bautista de Anza 

National Historic Trail 

Y Congressional 

Designation as 

National Historic Trail 

None assigned Isolated Occurrences N N/A 

None assigned Western Meat Packing 

building 

Effects of Eligible Resources 


N N/A 

The no build alternative would have no impacts to archeological and cultural 

resources in the project area. 


The preferred alignment would avoid all but 5 of the 16 cultural resources 

identified within the project area. Prior archaeological excavation or development 

destroyed two other sites; therefore, they warrant no further consideration. Three 

other sites were considered ineligible for the National Register and no treatment 

was proposed for those sites. The Pascua Yaqui cemetery was more than 0.25 mile 

from any ground disturbance that would result from construction of the preferred 

alternative. Because of the proximity of I-10, the preferred alternative would not 

produce noise or visual impacts that would adversely affect the historic integrity of 

the cemetery. 

The footprint of the preferred alternative would affect three resources, but the 

project is unlikely to adversely affect the historic qualities that make the properties 

eligible for the National Register. El Camino de Mañana would be realigned 



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slightly and the junction with the historic Red Rock Road would be abandoned. 

This would not affect the historic values of Red Rock Road. Expansion of Linda 

Vista Boulevard and its associated drainage improvements would disturb a short 

segment of the northern end of the earthen ditch at Concrete Weir and Earthen 

Ditch, but that would not affect the potential of the site to yield important 

information. The bridge crossing of the UPRR also would not adversely affect any 

historic values of this segment of the railroad, which passes through a setting 

highly modified by modern development. There is no physical evidence of the 

Juan Bautista de Anza National Historic Trail to preserve; however, the proposed 

bridges over the Santa Cruz River would be designed to accommodate the Juan 

Bautista de Anza National Historic Trail beneath and to improve access to this 

trail. 

The preferred alternative would be likely to result in adverse effects to two cultural 

resources: the Tucson-Casa Grande Highway, and the Stewart Brickyard Site. The 

impacts to each of these facilities is detailed in the following paragraphs. 

Tucson-Casa Grande Highway (SR 84) AZ AA:2:118(ASM) 

The preferred alternative cannot achieve its stated purpose and fulfill the 

documented needs in the project area without crossing the Tucson-Casa Grande 

Highway and reconstructing the roadway to match the elevation of the gradeseparated 

TI and to accommodate new I-10 on and off ramps. Although such 

effects would be considered adverse, they can be adequately mitigated by 

collecting and documenting information from the historic highway in accordance 

with the 2002 ADOT interim procedures for treating the historic state highway 

system. These procedures would be followed for the proposed project. 

Stewart Brickyard Site AZ AA:12:51(ASM) 

R/W acquisition, construction of the proposed access road, and the reconstruction 

of the eastbound I-10 frontage road would cross the Stewart Brickyard Site AZ 

AA:12:51(ASM). Although part of the frontage road would be within areas of the 

site that were destroyed previously by a sand and gravel pit, buried archaeological 

features may remain intact beneath other parts of the proposed roadways. To 

prevent damage to possible buried resources, prior to construction, a testing 

program would be developed for this site in consultation with SHPO. The testing 

program would define locations and frequencies of test excavations within this site 

to determine if significant archaeological deposits exist within the project area. 

Depending upon the results of the testing program, follow-up data recovery may 

be required also. 

Mitigation 

The Town of Marana would follow the terms and conditions of the Section 106 

programmatic agreement for I-10 improvements between the I-10/I-19 interchange 

and Tangerine Road signed by SHPO, FHWA, ADOT, and the Advisory Council 

on Historic Preservation in 1993 (included in Appendix D) and subsequently 

amended. In addition, the Town of Marana would follow the SHPO 



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recommendations to prepare a project specific treatment plan (see letter in 

Appendix D). 

The cultural resources inventory report prepared for this proposed project 

recommended a determination of adverse effect because of proposed project 

impacts on two National Register-eligible properties: the Tucson-Casa Grande 

Highway (SR 84) and the Stewart Brickyard archaeological site. Although such 

effects would be considered adverse, they would be adequately mitigated at both 

sites. The Town of Marana would mitigate adverse effects to two National 

Register-eligible properties: the Tucson-Casa Grande Highway (State Route 84), 

and the Stewart Brickyard archaeological site. Effects to the Tucson-Casa Grande 

Highway would be mitigated effectively by collecting and documenting 

information in accordance with the 2002 Arizona Department of Transportation 

interim procedures for the historic state highway system. To prevent damage to 

possible buried resources at the Stewart Brickyard archaeological site, a preconstruction 

testing plan would be developed and implemented for this site by the 

Town of Marana in consultation with ADOT Environmental and Enhancement 

Group’s Historic Preservation Team. The testing plan would define locations of 

test excavations within this site to determine if significant archaeological deposits 

exist within the area of potential effect. The Historic Preservation Team would 

consult with the SHPO as required. Depending upon the results of the testing 

program, follow-up data recovery may be required also. 

Minor gaps in the cultural resources inventory would be addressed by the Town of 

Marana as final design proceeds. These include completion of the archeological 

survey on parcels that could not be surveyed previously along the eastbound I-10 

frontage road and Linda Vista Boulevard because rights-of-entry could not be 

obtained. Archeological clearance would be obtained before geotechnical testing 

for bridge and embankment piers. 

According to Arizona Department of Transportation’s Standard Specifications for 

Road and Bridge Construction, Section 107.05 Legal Relations and Responsibility 

to Public, Archaeological Features (2000 Edition), if previously unidentified 

cultural resources are encountered during activity related to the construction of the 

project, the contractor shall stop work immediately at that location and shall take 

all reasonable steps to secure the preservation of those resources and notify the 

Engineer. The Engineer would contact the ADOT EEG, Historic Preservation 

Team (602.712.8636) immediately and make arrangements for the proper 

treatment of those resources. ADOT would, in turn, notify the appropriate 

agency(ies) to evaluate the significance of those resources. 

Agreement Documents 

SHPO, FHWA, ADOT, and the Advisory Council on Historic Preservation signed 

a Section 106 programmatic agreement for I-10 improvements between the I-10/I- 

19 interchange and Tangerine Road in 1993 (see Appendix D). This agreement 

established protocol and procedures to be followed for cultural resource 

investigations within the area covered by the agreement. This programmatic 



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agreement, as revised to address research design for treatment of archaeological 

resources, has been followed for this proposed project and would continue to be 

followed throughout the remainder of the project. 

In addition, ADOT interim procedures for treating the historic state highway 

system were developed in 2002. These procedures require the collection and 

documentation of information from the historic highway before construction that 

would impact these facilities. 

SHPO Concurrence 

SHPO has reviewed the cultural resources report prepared for this project and has 

concurred with all of the eligibility findings except that of the Tucson-Casa 

Grande Highway. SHPO stated that the segment of roadway within the project area 

contributed to its eligibility to the NRHP and that a project specific treatment plan 

would be needed (see letter in Appendix D). 

Conclusion 

The cultural resources report prepared for this proposed project recommended a 

determination of adverse effect because of proposed project impacts on two 

National Register-eligible properties: the Tucson-Casa Grande Highway (SR 84) 

and the Stewart Brickyard archaeological site. A strategy for mitigating adverse 

effects on these facilities was developed. Potential impacts on four other nearby 

National Register-eligible properties were evaluated and the project was 

determined to have no adverse effect on the historic qualities that make those 

resources eligible. Three other resources within the area of potential effect were 

recommended as ineligible for the National Register, and two other previously 

recorded properties had been destroyed. 

Socioeconomics 

Demographics 

According to the U.S. Census Bureau, the study area consisted of five census tracts 

within Pima County and the Town of Marana (Census Tracts 44.16, 44.20, 46.29, 

46.30, and 46.39), which represented a total 2000 population of 21,480. These 

census tracts are presented in Figure 4-5. Selected 2000 U.S. Census Bureau data 

from the five census tracts were compared to the same data for the Town of 

Marana, Pima County, and the State of Arizona in Table 4-10. Census data for 

these tracts is summarized in the following paragraphs. 

Census Tract 46.16 was the largest of the tracts, with a population of 8,841 

persons. Housing in this tract tended to be newer (94% constructed 1990 or after) 

and more frequently occupied by the owner (90.7%) when compared to the other 

tracts, the Town of Marana, Pima County, and Arizona. This tract also had a 

higher median family income ($60,172) when compared to the other tracts, the 

Town of Marana, Pima County, and Arizona. This census tract could be 



4-77 



44.20 

Avra 

Valley Rd 


Silverbell Rd 



44.16 

46.39 




4-78 

Cortaro Rd. 

Hartman Ln 

46.30 

46.12 


46.29 

46.34 

Thornydale Rd 

Figure 4-5 

Census Tracts 




Table 4-10. 2000 Selected Census Data 

Town of Pima State of Census 

Tract 

Census 

Tract 

Census 

Tract 

Census 

Tract 

Census 

Tract 

Marana County Arizona 44.16 44.20 46.29 46.30 46.39 

2000 Population 13,556 843,746 5,130,632 8,841 2,642 7,583 1,522 892 

RACE 

CHARACTERISTICS 

% White 84.3 77.8 77.9 87.5 68.2 90.5 94.2 92.7 

% Black 3.7 3.7 3.6 3.4 5.8 2.6 1.6 2.4 

% Indian 2.9 4.0 5.7 1.4 7.9 1.3 0.6 3.0 

% Asian 3.2 2.7 2.3 3.9 1.8 2.3 1.9 0.9 

% Other 8.7 15.1 13.2 6.6 19.3 6.2 3.9 5.6 

% Persons of Hispanic 

Origin 

AGE 


19.6 29.3 25.3 16.6 33.6 16.3 15.2 15.6 

% Below 25 years 34.2 35.6 36.8 34.0 35.3 40.9 36.2 35.7 

% 25 to 34 years 16.9 13.5 14.5 17.2 15.8 12.3 13.3 14.0 

% 35 to 54 years 29.5 28.0 27.2 30.7 28.9 36.4 35.3 33.5 

% 55 to 64 years 9.9 8.8 8.7 9.5 9.0 5.7 7.4 8.3 

% 65 to 84 years 9.1 14.2 11.7 8.0 10.4 4.4 6.9 8.2 

DISABILITY 

STATUS 

% Population 21 to 64 

years 

% Population 65 years 

and over 

ECONOMIC 


Median Family 

Income (1999) 

% Persons Below 

Poverty Level 

14.2 19.5 19.4 11.1 32.7 12.8 9.4 17.4 

28.3 40.7 39.7 28.3 63.5 29.1 56.6 25.8 

52,870 36,758 40,558 60,172 30,000 57,408 59,688 56,411 



6.2 n/a 13.9 2.1 15.0 3.5 1.0 8.1 

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HOUSING 


Occupied Housing 

Units 

Table 4-10. 2000 Selected Census Data 

Town of Pima State of Census 

Tract 

Census 

Tract 

Census 

Tract 

Census 

Tract 

Census 

Tract 

Marana County Arizona 44.16 44.20 46.29 46.30 46.39 

4,944 332,350 1,901,327 3,219 794 2,418 555 314 

% Owner Occupied 82.7 64.3 68.0 90.7 71.3 90.5 70.5 91.7 

% Renter Occupied 17.3 35.7 32.0 9.3 28.7 9.5 29.5 8.3 

OWNER OCCUPIED 

HOUSING VALUE 

% Under $50,000 1.1 4.3 4.9 0.3 16.9 0.7 2.0 0 

% $50,000-99,999 11.6 35.6 30.7 9.6 51.9 22.9 13.2 5.3 

% $100,000-149,999 48.7 29.6 30.7 51.9 19.0 68.7 30.6 57.4 

% $150,000-199,999 24.8 13.9 15.2 23.5 4.2 6.5 28.1 33.0 

% $200,000-or higher 13.7 16.7 18.6 14.7 8.0 1.3 26.1 4.3 

YEAR STRUCTURE 

BUILT 

% 1990 or after 80.1 23.2 29.3 94.3 20.1 36.2 69.2 57.7 

% 1980-1989 8.8 22.4 24.7 1.9 15.0 59.5 22.3 16.2 

% 1970-1979 5.8 25.6 23.6 1.9 34.1 3.1 8.6 19.2 

% 1960 or earlier 5.2 28.8 22.4 1.9 30.7 1.2 0.0 6.8 

n/a-Not applicable 

Source: 2000 U.S. Census Bureau 

characterized as a new residential area with a relatively affluent low minority 

population. 

The Census Tract 44.20 contrasted strongly with the other tracts in the study area 

and with the Town of Marana, Pima County, and the state. This tract had a total 

population of 2,642 persons with 7.9% Indian, 19.3% classified as other, and only 

68.2% white. This indicated a much higher minority population than surrounding 

census tracts, the Town of Marana, Pima County, and the State of Arizona. This 

was partially explained by the presence of a small pueblo of the Pascua Yaqui tribe 

(Yoem Pueblo) located near the northern portion of the study area. The median 

family income in this tract was the lowest in the study area at $30,000 and was 

even below the median family income of Pima County. The percentage of persons 

below the poverty level (15%) was also higher than the study area, the Town of 

Marana, the county, or the state. This tract had older homes (64.8% constructed 



4-80 




before 1979) and lower value homes (68.8% of the homes were worth $99,999 or 

less) than the other areas of comparison. This tract also showed a high percentage 

of disabled individuals in all age groups. This census tract could be characterized 

as an older area with lower incomes and a high minority and disabled population. 

Census Tracts 46.29, 46.30, and 46.39 resembled the characteristics of Census 

Tract 46.16. These tracts were characterized also by a relatively young, low 

minority, affluent population with newer, higher value homes. 

Minority Groups/ Title VI/Environmental Justice 

Title VI of the Civil Rights Act of 1964 and related statutes assure that individuals 

are not excluded from participation in, denied the benefit of, or subjected to 

discrimination under any program or activity receiving federal financial assistance 

on the basis of race, color, national origin, age, sex, and disability. EO 12898 

Federal Actions to Address Environmental Justice to Minority Populations and 

Low Income Populations requires federal agencies to consider impacts to minority 

and low income populations as part of environmental analyses to ensure that these 

populations do not receive a disproportionately high number of adverse human 

health impacts as a result of a federally funded project. FHWA issues a guidance 

document that establishes policies and procedures for complying with this EO in 

relation to federally-funded transportation projects (FHWA 1998). This guidance 

defines a “disproportionately high and adverse effect as one that is predominately 

borne by, suffered by, of that is appreciably more severe or greater in magnitude 

than the adverse effect that would be suffered by the non-minority population 

and/or the non-low-income population. 

As discussed above, the study area typically had a relatively low minority 

population, which reflected the overall population of the Town of Marana. 

However, Census Tract 44.20 exhibited a high Indian (7.9%), other (19.3%), and 

Hispanic (33.6%) population. This area represents the original incorporated area of 

Marana, while the remainder of the Town reflects a newer rapidly developing area. 

A small pueblo of the Pascua Yaqui tribe, the Yoem Pueblo, is located near the 

intersection of Sandario and Barnett Roads within Census Tract 44.20. Also of 

interest was the high percentage of disabled individuals in this tract. Although this 

census tract demonstrated the characteristics that would offer it protection under 

Title VI, EO 12898, and the ADA, as shown in Figure 4-5, this area is located in 

the extreme northern portion of the study area, approximately 8 miles from the 

project area. 

Because improvements would be distant from this area, the project would not 

affect this tract. In accordance with EO 12898, no disproportionately high and 

adverse human health or environmental effects upon minority and low income 

populations would occur as a result of the project. Pursuant to Title VI, individuals 

from the area would not be excluded from participation in, denied the benefit of, or 

subjected to discrimination as a result of the preferred alternative. In addition, the 

project would upgrade intersections and sidewalks within the project limits to be in 

compliance with the ADA and resulting regulations. The preferred alternative 



4-81 




could not be constructed in an area that would preferentially benefit this group. As 

discussed in Chapter 3, Alternatives, an alternative corridor location north of the 

preferred alternative was considered, but eliminated from further consideration 

because this location did not serve the proposed project’s demonstrated purpose 

and need. 

Neighborhood Continuity 

According to the Town of Marana’s General Plan Update, the Town is challenged 

to provide a sense of unity and accessibility to all public and private services 

because the Town boundaries are very widespread, development is irregularly 

shaped, and the Town is bisected by I-10 and the Santa Cruz River. This project 

would provide an additional connection between services east and west of I-10 and 

the Santa Cruz River, which would improve the sense of unity that the Town seeks 

to promote. 

The preferred alternative would also provide important improvements to bicycle 

and pedestrian facilities within the area of the Twin Peaks Road TI. In addition, 

the preferred alternative would improve access for constituents on the east side of 

I-10 to the Santa Cruz Shared Use Path and the De Anza National Historic Trail. 

These facilities may result in improved community cohesion and continuity. The 

project would also provide sidewalks and intersections within the project limits 

that would be in compliance with the ADA and resulting regulations. These 

improvements would provide enhanced access to those with mobility impairments, 

and generally would improve accessibility for all pedestrians in the area. 

Emergency Services 

Two agencies, the Town of Marana Police Department and the Pima County 

Sheriff’s Department, provide police services to the project area. Emergency 

medical services are provided by Northwest Fire and Rescue, a private service 

provider. Limited emergency services such as hospitals and other medical facilities 

service the project area, but none of these facilities are located within the project 

area. The hospital closest to the project area (Northwest Medical Center at Orange 

Grove and La Cholla Roads) is located approximately 7 miles from the project 

area. The new Northwest Medical Center near Tangerine Road and First Avenue is 

approximately 10 miles from the project area. 

Although these facilities would not be affected directly by the proposed 

improvements, Northwest Medical Center, at an early public agency scoping 

meeting for this project, stated that the at-grade crossings at El Camino de Mañana 

and Cortaro Road may result in extended delays for emergency medical personnel 

trying to transport individuals from the west side of I-10 to hospital facilities on 

the east side of I-10. These delays may be critical to some patients. An additional 

grade-separated crossing within the study area would improve the chances of 

getting to critical patients from the west side of the interstate to medical facilities 

on the east side of the interstate quickly and thereby improve the chances of 

survival for these individuals. 



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Social Services 

The project area is served by the Marana Unified School District. A second school 

district (Amphitheater Unified School District) is located near the study area, but 

east of Thornydale Road. There are several educational facilities located within the 

overall study area. Twin Peaks Elementary is located within the project area in 

Continental Ranch along Twin Peaks Road. Coyote Trail Elementary is located 

approximately 1.5 miles from the Twin Peaks Road TI. Tortolita and Marana 

Middle Schools are located approximately 3 and 7.5 miles from the Twin Peaks 

Road TI, respectively. Mountain View and Marana High Schools are located 

approximately 3.5 and 7.5 miles from the project area, respectively. These schools 

would not be affected directly by the proposed improvements; however, as 

discussed in Chapter 3, Alternatives, Mountain View High School families would 

benefit from the proposed improvements. 

Relocations/Displacements 

Residential 

The preferred alternative would displace permanently two occupied residences on 

commercial property in the project area. One of these residences is the only 

residence in the commercial area west of I-10 near the Twin Peaks Road TI. The 

proposed Twin Peaks Road extension to I-10 with its 300-foot R/W width would 

pass directly over this residence. The total commercial parcel of 2.3 acres would 

be acquired. Acquisitions and relocations are illustrated in Figure 4-6. 

The other residence proposed for displacement is located east of I-10 near the 

proposed new intersection of Twin Peaks Road/El Camino de Mañana/Linda Vista 

Boulevard. It is important to note, however, that this residence is leased for 

ranching in the area. This property is part of a large parcel that is planned for 

development; therefore, even if the Twin Peaks Road TI were not constructed, this 

residence would be removed by private interests. 

Commercial 

The preferred alternative would result in displacement and subsequent relocation 

of a number of occupied commercial properties. The proposed western 

reconstruction of the eastbound I-10 frontage road would result in the acquisition 

and relocation of all 8 commercial parcels between the access road and the 

eastbound I-10 frontage road north of Linda Vista Boulevard. An additional 

commercial property would be displaced at the new TI, and 2 commercial parcels 

near the southern intersection of the eastbound I-10 frontage road and the access 

road. These commercial displacements would result in total takes of 12.8 acres. 

The businesses displaced by the proposed improvements would be: 

• Eller Media Company 9741 N. Casa Grande Hwy 

• Amigos Nursery 9705 N. Casa Grande Hwy 

• Jarrell Pre-Cast 9685 N. Casa Grande Hwy 



4-83 




• Arizona Feeds/Alamo Saddlery/Bond’s Auction 9645 N. Casa Grande Hwy 

• Arrow Pump/Linda Vista Rent All 9635 N. Casa Grande Hwy 

• Quality Pallets 9625 or 9527 N. Casa Grande Hwy 

• Classi Carts 9601 N. Casa Grande Hwy 

• C & I Equipment 9421 N. Casa Grande Hwy 

• Cardi Used Equipment 9241 N. Casa Grande Hwy 

• Landscaping materials 9201 N. Casa Grande Hwy 

Temporary Impacts 

Access 

Construction activities would produce temporary interruptions to roadways on the 

east side of I-10. As a result of this, some short-term inconvenience would occur. 

During reconstruction of the eastbound I-10 frontage road, business access to the 

frontage road would be prohibited. To minimize impacts from these access 

restrictions and eventual loss of access (discussed under permanent impacts 

below), an access road would be constructed before frontage road reconstruction 

occurs. The access road would intersect with the eastbound frontage road north 

and south of the reconstruction area of the eastbound frontage road, providing a 

frontage road bypass during reconstruction of the frontage road. The frontage road 

would then be closed to traffic between the access road intersections until 

reconstruction was complete. To allow complete circulation within the area, the 

access road and the eastbound frontage road would remain two-way until the 

reconstruction of the frontage road is completed. After construction is completed, 

the eastbound frontage road would be changed to one-way operation, but the 

access road would continue to have two-way operation. 

Traffic Patterns/Service 

Temporary impacts to traffic patterns and service would not be very burdensome 

within the project area because Twin Peaks Road east of Continental Ranch and 

the Twin Peaks Road TI do not exist; therefore, there is no traffic to displace 

within most of the project area. The exception would be traffic that uses the atgrade 

crossing of the UPRR at El Camino de Mañana. During the initial 

construction phase, this at-grade crossing would be closed to traffic. The low 

volumes of traffic that use this crossing would be required to use Cortaro Road or 

another crossing of the UPRR. Because the only access point along the westbound 

frontage road between Cortaro Road and Avra Valley Road is at El Camino de 

Mañana, the westbound I-10 frontage road would be closed between Cortaro Road 

and Avra Valley Road until construction was completed. 



4-84 





4-85 

Figure 4-6 

Acquisitions and Relocations 




Business Disruption 

A traffic control plan would be developed that would maintain business access 

throughout project construction. The construction phase of the project may result in 

some temporary inconvenience for the businesses within the project area. The traffic 

control plan would be prepared in accordance with ADOT requirements and the 

specific needs of area businesses. Access would be maintained throughout the 

construction project; however, some inconveniences would be experienced by 

customers due to rerouting traffic from the eastbound frontage road to the access 

road. Signs would be posted to alert motorists of construction and to direct traffic 

to area businesses. 

Permanent Impacts 

Access 

The two-way supplemental access road was proposed to partially mitigate the 

effects of the proposed additional R/W acquisition and the loss of access near the 

Twin Peaks Road TI. ADOT’s Roadway Design Guidelines prohibit access onto 

frontage roads from slightly beyond the ramp/frontage road intersection through 

the intersection with the cross road (Twin Peaks Road). Prohibiting access in this 

area would minimize conflicts between low speed vehicles turning into and out of 

driveways with traffic exiting and entering the interstate at high speeds. Currently 

businesses in the area depend on access to the eastbound I-10 frontage road; 

therefore, the two-way access road would allow properties near the TI to access 

Twin Peaks Road, I-10, and the frontage roads after direct access onto the frontage 

road was eliminated. 

These businesses have developed their parcels to accommodate customer and 

service traffic access from the frontage road to the east. After frontage road access 

is eliminated, the businesses would be required to reorient their business 

operations to accommodate access from the west. Although this could be 

accomplished relatively easily by some property owners, others would find it 

difficult to accommodate this change. Some parcels are currently separated from 

the access road by parcels owned by others. Access across these parcels would be 

addressed during the final design of the proposed improvements and during R/W 

negotiations with individual property owners. 

Most users of the facility would experience improved access to points east and 

west of I-10, to I-10, and to the businesses along the frontage road with the 

completion of the preferred alternative. 

Traffic Patterns/Service 

The preferred alternative would improve most traffic patterns throughout the study 

area. The proposed grade-separation at the UPRR would prevent drivers from 

experiencing train-related delays on Twin Peaks Road and would reduce 

congestion on other local roadways, notably Silverbell and Cortaro Roads. The 

eastbound I-10 frontage road would be converted to one-way operation from the 



4-86 




Avra Valley TI south to the Cortaro Road TI, which would result in one-way 

frontage road operation from the Avra Valley TI to the 29 th Street TI. This would 

promote safer operations and would comply with ADOT policy. Provision of a 

new TI at Twin Peaks Road would improve traffic circulation within the overall 

area and serve a substantial amount of traffic both crossing and accessing I-10. 

Circulation within the study area would be improved also with the proposed 

construction of improved bicycle and pedestrian facilities. 

Residents within Continental Ranch would see a substantial increase in traffic 

volumes along Twin Peaks Road. Current two-way traffic volumes on Twin Peaks 

Road near the eastern terminus of the roadway are estimated to be approximately 

100 vehicles during the peak hour. After completion of the proposed 

improvements, two-way traffic volumes are estimated to increase to approximately 

2,510 vehicles during the peak hour by the year 2030; however, Twin Peaks Road 

was designed originally to provide this interstate connection. 

Business Disruption 

Although access to the businesses near the TI would be modified substantially with 

the loss of access to the eastbound I-10 frontage road, the resulting business access 

from the west would be safer and more convenient for customers. Currently 

customers must make right and left turns into these businesses from the high speed 

eastbound I-10 frontage road, which increases the risk of rear end and sideswipe 

crashes. The access road is a low speed facility and would be used primarily to 

access the businesses; therefore, the speeds and volumes on this roadway would be 

reduced and the resulting conditions would be safer for customers. In addition, the 

proposed improvements would provide new direct access to these businesses from 

Continental Ranch and from the east side of I-10. Currently customers must follow 

circuitous routes along the eastbound and westbound I-10 frontage roads to access 

the businesses. 

Mitigation 

The Town of Marana would conduct acquisitions and relocations in accordance 

with the Uniform Relocation Assistance and Real Property Acquisition Policies 

Act of 1970, as amended. Sections 28-1841 through 28-1853 of Arizona Revised 

Statutes provide for implementation of the Federal Relocation Assistance Program 

on a state level. In compliance with the Act, a relocation plan would be prepared. 

The Town of Marana would develop a traffic control plan that would ensure that 

access to businesses is maintained at all times. The traffic control plan would be 

prepared in accordance with Arizona Department of Transportation requirements 

and the specific needs of area businesses. Signs would be posted to alert motorists 

of construction and to direct traffic to area businesses. 

Businesses would reorient operations to accommodate access from the west. Some 

parcels are currently separated from the access road by parcels owned by others. 

Access across these parcels would be addressed during the final design of the 



4-87 




proposed improvements and during R/W negotiations with individual property 

owners. 

Conclusion 

Social and economic impacts may result if the proposed improvements: 1) produce 

changes in neighborhood or community cohesion or continuity; 2) specially 

benefit or harm protected groups; 3) affect highway and traffic safety, or overall 

public safety; 4) affect access to social services, schools or recreational resources; 

5) result in relocations or displacements of residents or businesses; 6) affect the 

economic viability of existing highway-related businesses through changes to 

access or disruptions to business activities; or 7) produce changes in travel patterns 

and accessibility. 

The preferred alternative would produce positive effects to overall public safety, 

access to services, and travel patterns and accessibility, especially for pedestrians, 

bicyclists, and the disabled. Impacts to business and residences would occur 

through acquisition and relocation and modification of access; however, these 

impacts would be minimized through relocations which follow the Uniform 

Relocation Assistance and Real Property Acquisition Policies Act of 1970, as 

amended, and Sections 28-1841 through 28-1853 of Arizona Revised Statutes. The 

traffic control plan developed for this project would ensure that access to 

businesses is maintained at all times. During the final design of the proposed 

improvements and R/W negotiations with individual property owners, providing 

access to the access road would be addressed. 

Section 6 (f) of the Land and Water Conservation Fund 

Act 

The Land and Water Conservation Fund Act (LWCFA) of 1965 established a 

grants-in-aid fund to assist states in the planning, acquisition, and development of 

outdoor recreational land and water areas and facilities. Section 6 (f) of the Act 

prohibits the conversion of any property acquired or developed with the assistance 

of the fund to anything other than public outdoor recreation use without the 

approval of the Secretary of the Department of Interior (DOI). The National Park 

System (NPS), within the DOI, administers the program at the federal level. At the 

state level, Arizona State Parks administers the program through the Grants and 

Recreation Programs Section. Town of Marana and Pima County Parks and 

Recreation Departments administer the program locally. 


Arthur Pack Regional Park, administered by Pima County, is located at 9101 N. 

Thornydale Road, south of Linda Vista Boulevard and west of Thornydale Road. 

Facilities available include ADA accessible facilities, golf course, lighted baseball 

and football/soccer fields, ramadas, basketball court, concession building, picnic 



4-88 




area, playground, restrooms, and drinking water on 500 acres. LWCFA funds were 

used in 1980 to build a softball field and again in 1983 for ball field lighting; 

therefore, this facility is protected under Section 6 (f) of the LWCFA. 

Impacts 


The no build alternative would not acquire recreational properties funded with 

LWCFA funds; therefore the no build alternative would have no impacts to 

Section 6 (f) facilities. The no build alternative would not improve access to or 

connectivity between recreational facilities or provide increased availability of 

bicycle or pedestrian facilities. 


The preferred alternative would not acquire recreational properties funded with 

LWCFA funds; therefore the preferred alternative would have no impacts to 

Section 6 (f) facilities. The preferred alternative would improve regional access to 

the recreational facilities. 

Mitigation 

No mitigation is required because no effects to Section 6 (f) facilities would result 

from the preferred alternative. 

Conclusion 

The preferred alternative would have no impacts to Section 6 (f) facilities, but 

would improve access to and connectivity between recreational facilities. 

Section 4(f) Department of Transportation Act 

Section 4(f) of the U.S. Department of Transportation Act of 1966 states that the 

FHWA “may approve a transportation program or project requiring publiclyowned 

land of a public park, recreation area, or wildlife and waterfowl refuge of 

national, state, or local significance, or land of a historic site of national, state, or 

local significance (as determined by the federal, state, or local officials having 

jurisdiction over the park, area, refuge, or site) only if there is no prudent or 

feasible alternative to using that land and the program or project includes all 

possible planning to minimize harm to the park, recreation area, wildlife and 

waterfowl refuge, or historic site resulting from the use” (49 U.S.C. 303). 

A use of a Section 4(f) resource, as defined in 23 CFR 771.135 (p), occurs: when 

land is permanently incorporated into a transportation facility; when there is a 

temporary occupancy of land that is adverse in terms of the statute’s 

preservationist purposes, and/or; when there is a constructive use of land. A 

constructive use of a Section 4(f) resource occurs when the transportation project 

does not incorporate land from the Section 4(f) resource, but the project’s 



4-89 




proximity impacts are so severe that the protected activities, features, or attributes 

that qualify a resource for protection under Section 4(f) are substantially impaired. 


Several existing or proposed Section 4(f) resources are located within the study 

area. No wildlife and waterfowl refuge areas exist within the study area. Section 

4(f) resources near the project area are shown on Figure 4-7. 

Impacts 


The no build alternative would not permanently incorporate, temporarily occupy, 

or constructively use 4(f) resources; therefore the no build alternative would have 

no impacts to Section 4(f) resources. The no build alternative would not improve 

access to or connectivity between recreational facilities or provide increased 

availability of bicycle or pedestrian facilities. 


Five Section 4(f) resources are located near the project area. Each of these 

resources and the potential impacts to each of the resources are discussed in the 

following paragraphs. 

Twin Peaks Elementary School 

Description of Resource: Twin Peaks Elementary School is a public school 

managed by the Marana Unified School District. Twin Peaks Elementary’s 

outdoor recreational facilities (approximately 6 acres) are used by the general 

public outside school hours. 

Use of 4(f) Resource: Twin Peaks Elementary is outside the area of construction 

for the proposed improvements and no temporary use of the recreational facilities 

would be required for construction purposes or temporary construction easements; 

therefore, the preferred alternative would not permanently nor temporarily 

incorporate any resources from this facility into a transportation facility. Although 

noise levels at the facility would increase with the preferred alternative, the noise 

analysis determined that the increase would not cause sound levels to exceed the 

FHWA’s NAC (see Noise section, page 4-49); therefore, no constructive use of the 

resource would occur. The preferred alternative would resurface Twin Peaks Road 

adjacent to the school; therefore, access to the resource may be temporarily 

impacted during this work. These temporary impacts would be minimized by a 

traffic control plan; therefore, no use of the 4(f) property would occur. The 

preferred alternative would improve overall access to this resource. 



4-90 



Avra 

Valley 

Rd 



Elementary School 

Silverbell Rd 



Juan Bautista de Anza National Historic Trail 

Santa Cruz River Shared Use Path 

School 

Park 




Union Pacific Railroad 

Cultural Resource 

4-91 

Cortaro Rd 

Hartman Ln 


Arthur Park 

Regional Park 

Thornydale Rd 

Figure 4-7 

4(f) Resources 


TRACS No.: 010 PM 236 H5838 01D


Measures to Minimize Harm: Temporary access impacts to recreational facilities 

would be minimized by developing and following a traffic control plan. The traffic 

control plan would be prepared in accordance with ADOT requirements and the 

specific needs of the school. Access would be maintained throughout the 

construction project; however, some inconveniences would be experienced by 

roadway users. 

Coordination Efforts: The school would be involved in the development of the 

traffic control plan. 

4(f) Conclusion: The preferred alternative would not permanently, temporarily, or 

constructively use any resources from this facility, and would minimize temporary 

access impacts to the resource through a traffic control plan; therefore, no use of 

the 4(f) property would occur. 

Santa Cruz River Shared Use Path 

Description of Resource: The Santa Cruz River Shared Use Path is under 

construction and will consist of a 14-foot wide paved trail for bicycle and 

pedestrian use that will connect with other community trails and bikeways, 

facilitating non-motorized access throughout the community and adjacent natural 

areas. The Santa Cruz River Shared Use Path is proposed to begin at Cortaro Road 

and proceed northward to the northern end of the Continental Ranch development 

where it connects via a drainage canal to approximately Coachline Boulevard, a 

total length of 3.75 miles. A one mile segment of the path exists also along 

Sanders Road northwest of the study area. The Town of Marana’s portion of the 

Santa Cruz River Shared Use Path, which is managed by the Town of Marana 

Parks and Recreation Department, is a section of the larger Pima County facility, 

which begins at Irvington Road and runs along the Santa Cruz River north to 

approximately Speedway Boulevard, a distance of approximately 6 miles. 

Avoidance Alternatives: Alternatives to the preferred alternative were considered 

and the impacts of these alternatives were assessed. The no-build alternative would 

not correct existing and future deficiencies in roadway design, roadway congestion 

on Cortaro Road and Silverbell Road, stormwater flowing over the I-10 mainline 

and frontage roads, motor vehicle conflicts with the railroad, and bicycle, 

pedestrian, and general transportation system connectivity. Therefore, the no-build 

alternative is not a prudent and feasible alternative. 

To solve the deficiencies noted above, all alignment alternatives examined must 

connect to the existing Twin Peaks Road alignment, which the Santa Cruz River 

Shared Use Path meets perpendicularly; therefore, alternative alignments to avoid 

the Santa Cruz River Shared Use Path were not prudent and feasible. 

A tunnel to carry the Santa Cruz River Shared Use Path beneath Twin Peaks Road 

at or near the path’s current alignment was examined, but the tunnel would be 

within the 100-year floodplain of the Santa Cruz River. This would create safety 

issues for path users during flood events, would require pumping facilities to 

remove water from the tunnel after flood events, and would require permanent 

lighting; therefore, this alternative was not prudent and feasible. 



4-92 




A bridge carrying pedestrians and bicyclists over Twin Peaks Road was considered 

also. The bridge concept had a number of disadvantages that resulted in 

elimination of its consideration. These included: cost; privacy and security of 

neighboring properties; hydraulic issues resulting from the placement of 

embankment and bridge piers within the floodway; visual impacts to neighboring 

properties; and, difficulty providing connections to the existing pedestrian and 

bicycle facilities along Twin Peaks Road. Therefore, there were no prudent and 

feasible alternatives to the use of the Santa Cruz Shared Use Path. 

Use of 4(f) Resource: As discussed in Chapter 3, Alternatives, the Santa Cruz 

Shared Use Path would be constructed prior to the construction of the preferred 

alternative; therefore, the preferred alternative would incorporate approximately 

500 feet of the adjacent path into the Twin Peaks Road extension, which is a use of 

the resource under 4(f). The preferred alternative would incorporate less than one 

percent of the path’s total length. 

At-grade shared use path crossings of Twin Peaks Road were not recommended 

because of potential vehicle conflicts; therefore, users of the shared use path would 

be diverted along the Twin Peaks Road embankment approximately 850 feet east 

of the shared use path’s alignment. To discourage pedestrian crossing of Twin 

Peaks Road at the former alignment of the Santa Cruz River Shared Use Path, the 

roadway’s center median would be fenced for approximately 100 feet in length. 

This would direct path users to either cross under the Santa Cruz River Bridge or 

at the nearest intersection to the west (Twin Peaks Road and Clover Road) using 

the existing sidewalk and shared use lanes on Twin Peaks Road. Although 

pedestrians and bicyclists would be diverted, the preferred alternative would not 

impair the use of the remaining 4(f) property for its intended purpose. 

Although noise levels in this area would increase with the preferred alternative, the 

increase would not cause sound levels to exceed FHWA’s NAC; therefore, no 

constructive use of the resource would occur. Construction of the preferred 

alternative would require temporary closure of the Santa Cruz River Shared Use 

Path during roadway and bridge construction; however, an alternative alignment of 

the Santa Cruz River Shared Use Path would be available during construction. As 

a result, no use of the 4(f) property would occur. 

The preferred alternative would provide a new connection across I-10 and the 

Santa Cruz River; therefore, the preferred alternative would improve access to this 

4(f) resource. 

Measures to Minimize Harm: Although the Santa Cruz River Shared Use Path 

would be closed during construction, an alternative alignment would be provided 

by diverting path users westward on Twin Peaks Road to the intersection of Twin 

Peaks Road and Clover Road. This crossing location would remain after 

construction is completed; therefore, no loss of access to the 4(f) property would 

occur during construction. 

The preferred alternative would divert pedestrians and bicyclists from the existing 

alignment of the Santa Cruz River Shared Use Path. This diversion was necessary 



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to maintain the intended purpose of the 4(f) property and protect the safety of 

resource users. The diversion would place users closer to the Santa Cruz River, 

which would broaden the users’ experiences on the facility. 

Coordination Efforts: The Town of Marana Parks and Recreation Department, 

who manages the Santa Cruz River Shared Use Path in this area, has been 

consulted regarding the preferred alternative and has submitted to the FHWA a 

letter of agreement for the proposed use of Santa Cruz River Shared Use Path (see 

Appendix E). The Parks and Recreation Department has concurred with the 

determination that there is no feasible and prudent alternative to the use of the 

portion of the path and that the preferred alternative would not have significant 

impacts upon the recreational utility of the path. The Parks and Recreation 

Department would continue to be involved as the project proceeds. 

4(f) Conclusion: Based upon the above considerations, there is no feasible and 

prudent alternative to the use of land from the Santa Cruz River Shared Use Path 

and the preferred alternative includes all possible planning to minimize harm 

resulting from such use. 

Juan Bautista de Anza National Historic Trail 

The Juan Bautista de Anza National Historic Trail is a planned 10-foot wide 

stabilized unpaved path along the Santa Cruz River for hiking, walking, and 

equestrian use that would commemorate the journey of de Anza from Nogales, 

Arizona to San Francisco, California. Although the Juan Bautista de Anza National 

Historic Trail does not exist and would not be constructed prior to the proposed 

construction of the preferred alternative, the Trail has been considered and 

incorporated into the design of the preferred alternative. The proposed Juan 

Bautista de Anza National Historic Trail would cross Twin Peaks Road beneath 

the proposed Santa Cruz River Bridges in the same area as the Santa Cruz River 

Shared Use Path. The proposed Santa Cruz River Bridges would be at least 10 feet 

above the ground surface in this area, allowing safe passage of equestrians below 

the bridge; therefore, the preferred alternative would not permanently incorporate 

any resources from this facility. Although noise levels in this area would increase 

with the preferred alternative, the area is adjacent to I-10 and the increase would 

not exceed the FHWA’s NAC; therefore, no constructive use of the resource 

would occur. The Juan Bautista de Anza Historic Trail does not exist; therefore, 

access to the resource would not be impacted during construction of the proposed 

alternative. 

Arthur Pack Regional Park 

Description of Resource: Arthur Park Regional Park is located in the eastern end 

of the Twin Peaks Road TI study area. It is a 500-acre facility managed by the 

Pima County Natural Resources, Parks and Recreation Department and provides 

ADA accessible facilities, a golf course, lighted baseball and football/soccer fields, 

basketball courts, concessions, picnic areas, playgrounds, and restrooms. 

Use of 4(f) Resource: No improvements to Linda Vista Boulevard are proposed in 

the vicinity of Arthur Pack Regional Park and access to the Park is from Hardy 



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Road; therefore, the preferred alternative would not permanently incorporate any 

resources from this facility nor impact access to the facility either permanently or 

temporarily. 

Construction of the preferred alternative would increase traffic volumes on Linda 

Vista Boulevard; therefore, traffic noise was predicted to increase adjacent to 

Linda Vista Boulevard. At hole #11 of the golf course, noise levels are predicted to 

increase from 63 to 67 dBA (A-weighted sound level in decibels) by the year 2030 

(see Noise Section, page 4-49). At this predicted noise level, FHWA and ADOT 

require that traffic noise mitigation be considered; however, because the sound 

levels do not exceed FHWA’s NAC, no constructive use of the 4(f) property 

would occur. 

Measures to Minimize Harm: Although noise levels were predicted to increase in 

this area, mitigation using noise barrier walls was not considered reasonable for 

Arthur Park Regional Park because: 1) golfers are exposed to this level of traffic 

noise for relatively short periods of time on the course; and, 2) walls would impose 

a visual restriction on views to the north and east from the golf course. 

Coordination Efforts: Pima County Natural Resources, Parks and Recreation 

Department, who manages Arthur Pack Regional Park, has been consulted 

regarding the preferred alternative and has submitted to the FHWA a letter of 

concurrence that the provision of noise mitigation walls for the Arthur Pack 

Regional Park is not reasonable (see Appendix E). 

4(f) Conclusion: The preferred alternative would not permanently, temporarily, or 

constructively use any resources from this facility; therefore, no use of the 4(f) 

property would occur. 

UPRR 

Description of Resource: The Southern Pacific Railroad main line (now the 

UPRR) across the entire state was determined eligible for the NRHP by the SHPO. 

Use of 4(f) Resource: According to the Cultural Resources Section (page 4-66), 

the preferred alternative would not adversely affect any historic values of this 

segment of the railroad, which passes through a setting highly modified by modern 

development. The preferred alternative would construct a bridge crossing of the 

UPRR, but would not incorporate any resources from this facility; therefore, no 

use of the 4(f) property would occur. Serenity and low noise levels are not 

contributing factors to the NRHP eligibility of this resources; therefore, no 

constructive use of the 4(f) property would occur with increased noise levels. 

While setting the bridge deck over the UPRR, temporary impacts to train traffic 

may occur; however, the UPRR has been involved in the planning of the project 

and would issue right-of-way grants or agreements for the bridge over their 

facilities. These temporary impacts would be of short duration, would not acquire 

any property (in the present or in the future), would produce no permanent adverse 

changes to the property, and would involve only the property in the project area, 

which is a very small portion of the statewide facility. 



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Measures to Minimize Harm: UPRR would require right-of-way grants or 

agreements for the Twin Peaks Road bridge over their railroad tracks. To issue 

these grants or agreements, UPRR would review the plans for the preferred 

alternative to ensure that the project met current UPRR standards for bridge 

design. UPRR would be involved also in the sequencing of construction plans to 

ensure that temporary disruptions to train traffic would be minimized. 

Coordination Efforts: SHPO has reviewed the cultural resources report prepared 

for this project and has concurred with the eligibility findings regarding the UPRR. 

The SHPO concurred that the bridge crossing of the UPRR would not adversely 

affect any historic values of this segment of the railroad, therefore, there would be 

no use of the 4(f) property. In addition, UPRR has been involved in the project 

since the beginning and has been a participating member of the Technical 

Advisory Team (TAC) for the project. Several meetings with the UPRR have been 

held in addition to the TAC meetings. The UPRR is an important participant in 

this project and would continue to be involved throughout the project. 

4(f) Conclusion: The preferred alternative would not permanently or constructively 

use any resources from this facility; therefore, no use of the 4(f) property would 

occur. The temporary impacts to the use of the facility would be minimized by the 

UPRR’s right-of-way grants or agreements process. 

Mitigation 

Temporary access impacts to recreational facilities at Twin Peaks Elementary 

would be minimized by developing and following a traffic control plan. Impacts to 

the Santa Cruz Shared Use Path would be mitigated by realigning and 

reconstructing the Path along the Twin Peaks Road embankment to direct path 

users to cross under the Santa Cruz River Bridges. The temporary closure of the 

Santa Cruz River Shared Use Path during roadway and bridge construction would 

be mitigated by diverting path users westward on Twin Peaks Road to the Twin 

Peaks Road/Clover Road intersection. This additional crossing location would 

remain after construction is completed. Prior to construction of the Twin Peaks 

Road bridge over the railroad, the UPRR would review the plans for the preferred 

alternative to ensure that the project met current standards for bridge design. 

UPRR would be involved also in the sequencing of construction plans to ensure 

that temporary disruptions to train traffic would be minimized. 

Conclusion 

The preferred alternative would not permanently, temporarily, or constructively 

use any resources from the Twin Peaks Elementary School recreational facilities, 

and would minimize temporary access impacts to the resource through a traffic 

control plan; therefore, no use of this 4(f) property would occur. The preferred 

alternative would not permanently, temporarily or constructively use any resources 

from the Juan Bautista de Anza National Historic Trail, nor the Arthur Pack 

Regional Park; therefore, no use of these 4(f) properties would occur. The 

preferred alternative would not permanently or constructively use any resources 



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from the UPRR; therefore, no use of the 4(f) property would occur. The temporary 

impacts to the use of the facility would be minimized by the UPRR’s right-of-way 

grants or agreements process. 

The only Section 4(f) resource that would be incorporated into the preferred 

alternative is the Santa Cruz River Shared Use Path. Approximately 500 feet of the 

Santa Cruz Shared Use Path, which is less than one percent of the path’s total 

length, would be incorporated into the preferred alternative. The Town of Marana 

Parks and Recreation Department, who manages the Santa Cruz River Shared Use 

Path in this area, concurred with the determination that there is no feasible and 

prudent alternative to the use of the portion of the path and that the preferred 

alternative includes all possible planning to minimize harm resulting from such 

use. 

Utilities and Railroad 


There are a number of utilities within the study area. The most conspicuous of 

these utilities are 90-foot tall towers that support three sets of 138 kv TEP 

transmission lines. These towers are parallel to and approximately 150 feet east of 

the UPRR. Other overhead utilities include electric service lines owned by TEP 

and by Trico Electric. 

The Union Pacific Transportation Company provides freight rail service along I-10 

for the central and southern portions of the state. The UPRR line runs parallel to 

and east of I-10 in the vicinity of the Twin Peaks Road TI. There is a heavy 

concentration of underground utilities within the 200-foot R/W of the UPRR. 

Known utilities include three high-pressure petroleum lines (6-, 8-, and 12-inch 

lines belonging to Kinder Morgan) and numerous fiber optic communications lines 

on both sides of the tracks (belonging to Sprint Communications, Qwest, MCI 

Communications, Williams Communications, Level 3 Communications, AT&T 

Communications, and UPRR’s internal communication facilities). AT&T also has 

service lines on the west side of I-10 within the study area. 

Other underground utilities include natural gas and water lines which serve 

Continental Ranch and the commercial area west of I-10, that are owned by 

Southwest Gas and Tucson Water, respectively. Tucson Water’s well # Y004 

(7201 W. Twin Peaks Road) is located approximately 50 yards north of Twin 

Peaks Road. Pima County Wastewater Management serves the Continental Ranch 

area where a sanitary sewer lift station pumps sewage east of the Santa Cruz River 

for treatment at the Ina Road Wastewater Treatment Plant; however, sewage in the 

commercial area west of I-10 is treated by on-site individual septic systems. 

Continental Ranch is served also by buried television cable lines belonging to 

Comcast Cable. 

The CMID operates two wells within the project area which transmit flow under 

I-10. The CMID operates an open irrigation canal along the east side of I-10, 



4-97 




between the westbound lanes and the westbound frontage road. There are 

numerous private wells in the area as well. According to the Arizona Department 

of Water Resources, at least 21 registered wells are located near the study area. 

There may also be other, unrecorded wells within the area. 

Impacts 


The no build alternative would not affect the existing utilities within the project 

area. 


The utilities of greatest concern within the project area are the 138 kv TEP 

transmission lines, the UPRR, and the Kinder Morgan high-pressure petroleum 

lines. As discussed in Chapter 3, Alternatives, the preferred alternative was 

designed to avoid relocation of the 138 kv TEP transmission lines. Subsequent to 

the selection of the preferred alignment, design changes were required. The UPRR 

proposed to add a second track on the east side of the existing track and to increase 

the elevation of the added track above that of the existing track. In addition, revised 

traffic projections indicated that additional traffic lanes on the bridge over the UPRR 

may be needed. As a result, the height of the bridge over the UPRR was adjusted 

and the bridge width was increased to accommodate more traffic lanes at a later 

time. These design changes would require that one or more of the transmission line 

towers be relocated or raised. 

While setting the proposed bridge deck over the UPRR, temporary impacts to train 

traffic may occur; however, the UPRR has been involved in the planning of the 

project and would issue right-of-way grants or agreements for the bridge over their 

facilities. To issue these grants or agreements, UPRR would review the plans for 

the preferred alternative to ensure that the project met current UPRR standards for 

bridge design. UPRR would be involved also in the sequencing of construction 

plans to ensure that temporary disruptions to train traffic would be minimized. 

UPRR has been involved in the project since the beginning and has been a 

participating member of the Technical Advisory Team (TAC) for the project. 

Several meetings with the UPRR have been held in addition to the TAC meetings. 

The UPRR would continue to be involved throughout the project. 

According to plans provided by Kinder Morgan, the proposed improvements 

would avoid the high pressure petroleum lines. This would be verified during final 

design, by potholing utilities to verify their locations. Other utilities within the 

project area may require slight adjustments. The preferred alternative would pipe 

and bury portions of the CMID irrigation canal that is located along the east side of 

I-10. Utility coordination was initiated as part of the planning process and would 

continue throughout the course of the project. Schedules for any utility 

adjustments would be closely coordinated to minimize interruptions and 

inconvenience to customers. 



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The preferred alternative would acquire commercial property for needed R/W. The 

commercial properties between I-10 and the access road dispose of liquid waste 

through individual septic tanks and some have individual water supply wells. In 

some areas, acquisitions of areas in which septic tanks are buried or wells are 

located may be required. During R/W negotiations, as a part of final design, these 

utilities would be located and relocations or avoidance may be required. 

Mitigation 

The preferred alternative would require the relocation or raising of the 138 kv TEP 

transmission lines in the project area. Coordination with TEP has been ongoing 

throughout the project and would continue throughout the design phase of the 

project. The relocation or raising of the 138 kv transmission lines would be 

coordinated closely with TEP. 

While setting the proposed bridge deck over the UPRR, temporary impacts to train 

traffic may occur; however, the Town of Marana would provide plans for UPRR 

review to ensure that the preferred alternative met current UPRR standards for 

bridge design and that the sequencing of construction minimized temporary 

disruptions to train traffic. 

During final design, potholing would be used to verify utility locations. Although 

the major utilities would be avoided by the preferred alternative, some utilities 

within the project area may require slight adjustments. Utility coordination would 

be maintained throughout the course of the project and schedules for any utility 

adjustments would be coordinated closely to minimize interruptions and 

inconvenience to customers. 

If asbestos-containing water lines are moved or replaced during the roadway 

construction, the lines would be handled, transported, and disposed of in accordance 

with approved federal, state, and county asbestos handling procedures. This would 

include appropriate precautions to ensure that employees are not exposed to airborne 

asbestos fibers and that fibers are not released into the atmosphere. 

As a part of final design and R/W acquisition, the Town of Marana would establish 

the locations of private wells and septic tanks would be established for acquired 

properties and any necessary relocations would be coordinated with the property 

owners. 

The Town of Marana would coordinate with the CMID prior to any modifications 

of the canal and construction would be coordinated so that the proposed 

improvements would not interfere with the supply of irrigation water during critical 

periods. 

The Town of Marana would maintain utility coordination throughout the course of 

the project and schedules for any utility adjustments would be coordinated closely 

to minimize interruptions and inconvenience to customers. Utility clearances 

obtained by the Town of Marana would be in accordance with ADOT requirements. 



4-99 




Conclusion 

Construction of the preferred alternative would require that one or more of the 138 

kv TEP transmission line towers be relocated or raised. Close coordination with 

TEP would minimize interruptions and inconvenience to customers. While setting 

the proposed Twin Peaks Road bridge deck over the UPRR, temporary impacts to 

train traffic may occur; however, UPRR would review the plans and would be 

involved in the sequencing of construction to ensure that temporary disruptions to 

train traffic would be minimized. Some private wells and septic tanks may be 

affected by the proposed improvements. The preferred alternative would modify 

the CMID canal, but the proposed improvements would not interfere with the 

supply of irrigation water during critical periods. Utility coordination would be 

maintained throughout the course of the project and schedules for any utility 

adjustments would be coordinated closely to minimize interruptions and 

inconvenience to utility users. If asbestos-containing water lines are moved or 

replaced during the roadway construction, precautions would be implemented to 

ensure that the asbestos-containing material would be handled safely. 

Material Sources and Waste Materials 

Quantity of Borrow 

The preferred alternative would construct Twin Peaks Road, the Santa Cruz River 

bridges, Twin Peaks Road bridge over I-10 and the UPRR on elevated 

embankments. Although the preferred alternative would generate excavation 

material from the widening of the low flow channel of the Santa Cruz River, the 

project would still require approximately 640,000 cubic yards of borrow material. 

Availability 

Sand and gravel mining operations operate within the study area. An existing sand 

and gravel mining operation (I-10 Avra Valley Mining and Development) is 

located on the west side of the Santa Cruz River south of Avra Valley Road, which 

is north of the project area. Another active sand and gravel mining operation 

(Rinker Materials) is located in the southern project area immediately south of the 

south access road. 

Status of Clearance of Sites 

Any material sources required for this project outside of the project area would be 

examined for environmental effects, by the contractor, prior to use, through a 

separate environmental analysis in accordance with Arizona Department of 


Section 1001 Material Sources (2000 Edition) (Stored Specification 1001.2 

General), unless the facility has received prior clearance from the EEG of ADOT. 

According to Rinker Materials, their materials pit has received environmental 

clearance to provide materials to ADOT; therefore, materials from this site could 



4-100 




be used without additional clearance activities. The clearance status of the I-10 

Avra Valley Mining and Development site is unknown; therefore, it is assumed 

that clearance would be required to receive materials from this site. 

Conclusion 

Sources of borrow material are near the project area. Depending on the supplier 

chosen to provide materials, environmental clearance from ADOT EEG would or 

would not be required. 

Construction Water Source 

Construction water may be required for slurry drilling if soils are susceptible to 

cave-in or slough into the drilled hole. Water would be required also general 

material mixing and for dust suppression during soil disturbing activities. All 

water would be obtained from approved sources of potable water and no wells 

would be drilled in the project area. 

Secondary Impacts 

According to the Council on Environmental Quality (CEQ), a direct effect is one 

that is caused by the proposed action and occurs at the same time and place. The 

direct effects of the preferred alternative have been discussed in the previous 

sections of this chapter. A secondary effect is defined by CEQ as one that is 

caused by the action, but is later in time or farther removed in distance; however, 

the effect is still reasonably foreseeable. The CEQ cites induction of growth, 

changes in land use, or effects to air, water, or ecosystems as examples of 

secondary effects. However, the transportation demand models that generated 

traffic projections for the noise and air quality analyses for this project considered 

proposed growth and changes to the transportation network; therefore, these 

effects have been addressed. As discussed earlier, incompatible use or 

development within the Santa Cruz River floodplain would not be facilitated by 

the preferred alternative because developments within the area must comply with 

the Town of Marana or Pima County zoning and floodplain ordinances. It was 

noted also that the proposed revegetation plan would maintain or enhance habitat 

and connectivity important to the survival and successful dispersal of wildlife, 

including protected species. Relevant secondary impacts to this project include 

land use and access. 

Land Use 

The types of commercial enterprises near the Twin Peaks Road TI may change after 

completion of the proposed improvements. Currently the commercial activities near 

I-10 are wholesale and retail operations, equipment repair services, and light mining 

and manufacturing. After the Twin Peaks Road TI is constructed, it is possible that 

some of these activities would be replaced by service-oriented businesses 

(hotel/motel, restaurant, etc.) that are typical of interstate interchange locations. 







These effects, however, are market driven. Properties with easy access to an 

interstate become more desirable for service-oriented businesses; therefore, it is 

likely that property values in the vicinity of the Twin Peaks Road TI would increase 

substantially after completion of the Twin Peaks Road TI. As a result, businesses 

may choose to sell existing properties and relocate their businesses to parcels of 

lesser value. 

Access 

SNP 1988 General Management Plan (GMP) stated a desire to close Picture 

Rocks Road through the SNP, if the Twin Peaks Road TI is constructed. SNP is 

updating its GMP currently and the NPS is obtaining public comments and 

developing proposed uses for the Park; however, the closure of Picture Rocks 

Road through SNP does not appear in any of the alternatives currently under 

consideration. Because the closure of Picture Rocks Road is not proposed 

currently and any proposed closure would be subject to environmental and public 

review based upon its own merits, the impacts of the closure of Picture Rocks 

Road are not discussed in this EA. 

Conclusion 

Secondary impacts to land use and access may occur with the completion of the 

preferred alternative. These may include changes to land uses near the Twin Peaks 

Road TI and access through the SNP. 

Cumulative Impacts 

According to the CEQ, cumulative effects are defined as the impacts on the 

environment that result from the proposed action when added to other past, 

present, and reasonably foreseeable future actions. The cumulative effects of this 

project may be undetectable when considered for its direct and secondary effects 

only, but may add to a measurable environmental change. 

The past, present, and reasonably foreseeable future actions that are considered in 

this analysis include the transportation projects planned over the next 20 years, as 

represented in the 2025 RTP, and the development expected to occur within the 

area. In addition, a number of conservation efforts are underway in the region and 

these efforts are expected to mitigate some of the development impacts. The area of 

analysis is the northwest portion of the Tucson metropolitan area, although air 

quality is discussed from an airshed perspective. For this assessment, only those “at 

risk” critical resources would be evaluated. These would include: land use, air 

quality, threatened and endangered species and natural resources, noise, and water 

resources. Each are discussed below. 

Land Use 

The completion of the projects contained within the RTP may result in additional 

development beyond those forecast in the area; however, these developments are 







controlled by the formal planning processes, zoning regulations, land use codes 

and regulations, and other land use controls of the Town of Marana and Pima 

County. As a result, it is reasonable to assume that these developments would 

comply with these regulations and ordinances and reflect the overall development 

patterns approved by the Town of Marana and Pima County. Because the 

developments would comply with land use regulations, the infrastructure needed to 

supply this growth (i.e. water supply, sewer and/or other utilities) would be 

provided also. 

Air Quality 

Pima County and the State of Arizona have programs in place to address 

particulate matter and CO. Because Pima County is classified as attainment under 

a limited maintenance plan for CO, the County must meet the conformity provisions 

of the federal Clean Air Act and subsequent amendments. As a result, all 

transportation projects that appear in the RTP are analyzed and the preferred 

alternative, along with past, present, and reasonably foreseeable future 

transportation projects have been demonstrated to not contribute to a CO 

nonattainment designation. Likewise, regulatory controls in Pima County are likely 

to protect the County from reaching nonattainment for particulate matter despite 

future development. 

As the area develops, sources of volatile organic compounds and oxides of nitrogen 

would be added to the area (gasoline stations, vehicles, lawnmowers, etc.); therefore, 

it is likely that the airshed’s ground level ozone levels would increase. Recent local 

data from PAG indicate that the Tucson region experiences ozone levels 

approaching the 8-hour federal standard. It is likely that ozone levels would 

continue to increase and additional control measures may be required to keep the 

area in attainment of the standard. 

Threatened and Endangered Species and Natural Resources 

As discussed in the Biological Resources section (page 4-25), the analysis 

conducted for the preferred alternative determined that the proposed action may 

affect, but is not likely to adversely affect the CFPO or its habitat due to the 

project design and mitigation measures that would be implemented as a part of this 

project. Although the listing of the owl as an endangered species is under review 

by the courts, the protections afforded the owl are still in place. If the owl is 

delisted, it is anticipated that one or more of three major conservation efforts 

proposed by the Town of Marana and Pima County would be in place and 

protection to the owl would be continued. These efforts are: 1) Pima County’s 

SDCP; 2) the Town of Marana’s Habitat Conservation Plan; and, 3) the Town of 

Marana’s Bajada Environmental Resource Overlay District. All of these programs 

are designed to preserve appropriate CFPO habitat and provide contiguous 

corridors between quality habitat areas, while allowing limited development to 

occur in areas deemed less desirable for the CFPO. Other animal species, 

vegetation, and natural surface features would benefit also from these efforts. 







Noise 

As the area develops and additional or higher capacity transportation facilities are 

constructed, sources of noise (vehicles, general human activities, air travel, etc.) 

would increase; therefore, it is likely that the relatively low background noise levels 

in the area would increase as well. 

Water Resources 

As the area develops, the demand for water to serve an increasing population would 

continue to increase. Water providers in the area have, or are developing, long range 

master plans for their facilities. As a result, it is likely that additional conservation 

methods, water sources, and/or regulatory controls would be required to provide 

water to the increasing desert population. 

Conclusion 

As the area develops, the function and appearance of the land would change and 

additional demands upon resources would occur. These changes would occur with 

or without the construction of the preferred alternative, but these changes would 

reflect the overall development patterns approved by area governments. 






Public Involvement/Project Coordination October 2005 

CHAPTER 5: PUBLIC INVOLVEMENT/PROJECT 

COORDINATION 

To ensure that the public contributed to this study and had full access to study results, a 

public involvement plan was prepared early in this project. The public involvement plan for 

this project included contact with numerous federal, state, and local agencies, utility 

companies, and residents and business owners potentially affected by the project. 

The Public Information Meeting and Public Hearing process had three phases: 1) identify 

public issues, goals, and objectives; 2) relay alternatives to the public based upon number 

1; and, 3) present the preferred alternative in a public hearing. 

Scoping Activities 

Agency scoping for this project reaches back several years. Numerous meetings were 

held between the Town of Marana and ADOT, USFWS, AGFD, the Corps, and the NPS 

to fully understand agency concerns and to proactively address these concerns. 

Partnering Session - Comments and Response Summary 

On March 13, 2003, a partnering session was conducted with the Town of Marana, 

FHWA, ADOT (both district and statewide representatives), resource agencies (AGFD), 

and the study consultant team. The meeting was intended to: 

• introduce the participants to each other; 

• present a project overview; 

• identify project challenges and opportunities; 

• establish a project management submittal review structure; 

• discuss challenges and opportunities; and, 

• develop an issue escalation ladder and assign project processes and 

responsible parties. 

A number of project issues and challenges were identified by the partnering participants. 

As a result of the partnering session, the issues and opportunities discussed have been 

investigated during the study. An Executive Committee was created and has met 

throughout the course of the study. Executive Committee membership includes ADOT 

district and statewide planning staff, FHWA, and the Town of Marana. In addition, clear 

lines of authority were established for the project and these lines of authority have been 

followed throughout the project study. Several technical committees were also formed. 

General Agency Scoping Meeting - Comments and Response Summary 

A general agency scoping meeting was held on September 29, 2003 to solicit comments 

and concerns related to the Twin Peaks Road TI. A list of agencies invited to attend or to 

submit comments by telephone, electronic mail, or mail and a copy of the invitation letter 

is included in Appendix A. Those agencies and utilities that attended the meeting 



5-1 




included: Marana Town Council, Marana Town Manager, Marana Public Works 

Department, Marana Planning Department, Marana Police Department, PAG, 

PCDOT&FCD, ADOT, Northwest Medical Center, and Trico Electric. Correspondence 

received from agencies in response to this request may be found in Appendix A. 

The intent of the agency scoping meeting was to obtain comments or concerns to be 

considered in the development of the Design Concept Report and environmental 

documents for the Twin Peaks Road TI. The meeting goals were to inform the agencies 

of the proposed project and to establish communication lines between the project 

development team and the concerned agencies. Several TI design concepts including 

shifting the I-10 alignment, an elevated or depressed crossroad over or under I-10, grade 

separation with the UPRR, and the use of a SPUI were discussed. These items have been 

considered and are addressed in Chapter 3, Alternatives. 

Special Environmental Scoping Meetings - Comments and Response Summary 

A meeting was held on Monday, August 25, 2003 at FHWA offices in Phoenix to 

coordinate environmental efforts currently taking place on the Twin Peaks Road TI 

project. Attendees included the Town of Marana, FHWA, AGFD, Corps, ADOT, and the 

consultant team. The meeting discussed the proposed project’s background, proposed 

scope, and issues. The meeting asked for comments on the proposed project approach. 

The level of environmental effort was discussed, both in general (e.g. environmental 

assessment versus environmental impact statement) and specific to particular issues (e.g. 

biological evaluation). 

A follow–up meeting was held on September 2, 2003 with agencies unable to attend the 

August 25 meeting. The meeting was attended by the Town of Marana, USFWS, ADOT, 

and the consultant team. The routing and review of environmental documents was 

discussed. The content of biological investigation documents was discussed and 

agreement was reached on content and species to be considered. Methods of possible 

mitigation for removal of vegetation were discussed. 

Environmental Working Group - Comments and Response Summary 

An environmental working group was established to maintain open communication 

between the Town of Marana, ADOT, FHWA, resource agencies, and the project 

consultant team. The group met on three occasions (October 1, 2003, and January 8 and 

May 13, 2004). The major points from each of the meetings are summarized below. 

The first meeting was held on Wednesday, October 1, 2003. The meeting was attended 

by the Town of Marana, FHWA, ADOT, and the consultant team. Meetings with several 

of the property owners in the study area had been conducted and a summary of comments 

received from the property owners was discussed. Coordination with other projects 

within the study area (especially trail projects) was discussed. 

The second meeting of the group was held on January 8, 2004. The meeting was attended 

by the Town of Marana, FHWA, ADOT, and the consultant team. The meeting discussed 

relationships with the SNP and the proposed closure of Picture Rocks Road by the NPS. 

This issue is discussed in detail in Chapter 4, Affected Environment. Coordination with 

other ongoing projects in the study area was also discussed. 



5-2 




The third meeting of the environmental working group was held on May 13, 2004. The 

meeting was attended by the Town of Marana, FHWA, ADOT, USFWS, AGFD, and the 

consultant team. The intent of the meeting was to update all parties on the current status 

of the project and to solicit comments on the proposed design so that suggestions could 

be considered for incorporation into the project plans. The Town of Marana’s three year 

survey efforts for the CFPO were discussed. Coordination with other ongoing projects in 

the study area was discussed. Construction techniques and timing within the Santa Cruz 

River and maintenance or replacement of vegetation were discussed. The sizing of 

drainage facilities on both sides of the interstate to accommodate wildlife crossing was 

discussed. 

Scoping Meeting with Saguaro National Park - Comments and Response Summary 

At the request of the NPS, a meeting was held on November 13, 2003. Attendees 

included the Town of Marana, NPS, and the project consultant team. Project issues 

related to SNP are discussed in detail in Chapter 4, Affected Environment. The first public 

information meeting for the Twin Peaks Road TI was discussed. NPS supports the Twin 

Peaks Road TI and expressed a desire to close Picture Rocks Road through SNP after the 

TI is constructed. 

Technical Advisory Committee (TAC) Meetings - Comments and Response Summary 

The TAC was formed early in the project to help guide decisions. The TAC consisted of 

technically based individuals who participated in discussions and review of documents and 

concepts. Several potentially impacted agencies served on the TAC and this provided a 

broader perspective to the project. Members of the TAC included representatives from the 

Town of Marana, ADOT, FHWA, UPRR, PAG, PCDOT&FCD, and the consultant team. 

The TAC met on October 1, 2003 and on January 8, February 26, and May 13, 2004. 

Public Information Meetings 

A number of meetings with the affected community have been conducted. These have 

included a collective meeting with residential property owners, meetings with the 

Continental Ranch and Sunflower Neighborhood Associations, two public information 

meetings, two collective meetings with area business owners, and numerous meetings with 

individual residential property owners and business owners. 

Property Owner Informational Meeting - Comments and Response Summary 

Meetings with the Continental Ranch and Sunflower Neighborhood Associations were 

held on August 26, 2003 and August 27, 2003, respectively. A total of 20 attended the 

Continental Ranch presentation and approximately 100 attended the Sunflower 

presentation. Comments and questions from the associations and responses to the 

comments and questions are presented in the following table. 



5-3 




Comment: Would like to see a bridge over the railroad tracks. 

Response: A grade-separated railroad crossing is part of the proposed improvements 

(see Chapter 3, Preferred Alternative, page 3-11). 

Comment: What are the predicted traffic volumes for Twin Peaks Road and the 

interchange? 

Response: According to the Traffic Report, 21,100 vehicles per day and 28,900 vehicles 

per day would use Twin Peaks Road west and east of the interchange by the year 2030, 

respectively. 

Comment: Will the design concept coordinate with the DeAnza Trail? 

Response: Yes, the DeAnza Trail would cross beneath the Twin Peaks Road bridges 

over the Santa Cruz River. The bridge would be of sufficient height to allow equestrians 

to pass beneath the bridges (see Chapter 3, Preferred Alternative, page 3-11). 

Comment: Will the traffic volumes take into account the new Continental Reserve 

development? 

Response: Yes, the traffic projections provided for this project include planned growth 

in employment and population in the entire area through the year 2030. 

Comment: Will there be sound walls along Twin Peaks Road? 

Response: The traffic noise analysis recommended sound walls only along the west side 

of Continental Ranch south of Twin Peaks Road. The existing privacy walls along Twin 

Peaks Road are effective at mitigating traffic noise (see Chapter 4, Noise Section, page 

4-49). 

Comment: Why does the process take so long? Can design be done during the planning 

process to speed things up? 

Response: This project would utilize federal funds and must follow the federal process; 

therefore, final design may not proceed until after the environmental documentation is 

completed. 

Comment: What about widening some of the other roads, like Silverbell from Cortaro to 

Ina? 

Response: Silverbell Road from Cortaro Road to Ina Road is anticipated to be 

constructed and widened prior to the completion of this project; however, widening 

other roads does not accomplish the project’s established purpose and need (see 

Chapter 2, Project Need, page 2-2). 

Comment: How will we get in and out of Sunflower, if Twin Peaks is extended and 

becomes busier? 

Response: Traffic signals are proposed at the intersections of Twin Peaks 

Road/Coachline Road and Twin Peaks Road/Access Roads; therefore, the signals would 

produce gaps in traffic needed to cross the traffic lanes. The existing median opening at 

Sunflower Ridge Road would remain also, providing a storage area for turning vehicles. 



5-4 




Comment: Will we be meeting again with Sunflower? 

Response: Yes, several meetings with the public would occur during the project. A 

public hearing on the EA would occur. 

Comment: What will happen at Twin Peaks Elementary School when traffic increases 

on Twin Peaks Road? 

Response: According to the Traffic Report, most pedestrian and bicycle traffic to Twin 

Peaks Elementary School originates south and east of the school. A shared use path was 

proposed south of Twin Peaks Road, but is not a part of this project (see Chapter 3, 

Preferred Alternative, page 3-11). The proposed traffic signals at the intersections of 

Twin Peaks Road/Coachline Boulevard and Twin Peaks Road/Silverbell Road would 

enable pedestrians to safety cross at these intersections. The Town would work closely 

with the Marana Unified School District on appropriate crossing measures. 

Letters were sent to approximately 93 homeowners closest to the project inviting them to 

one-on-one meetings that were held in early September. The team met with residents on 

Saturday September 6, 2003 from 9:00 a.m. to 12:00 p.m. and on Wednesday September 

10, 2004 from 4:00 p.m. to 7:00 p.m. These meetings took place in the small conference 

room at the Sunflower Community Center. A total of 10 property owners within 

Continental Ranch scheduled individual appointments to meet with members of the 

project team to learn about the proposed project, ask any questions, and provide input. 

Residents were concerned about the increase in traffic and noise associated with the Twin 

Peaks Road TI. The people who lived along the Santa Cruz River were concerned about 

visual impacts. Other concerns were the ability to get into and out of the side streets and 

safety concerns for the children walking to school. 

Public Information Open House #1 - Comments and Response Summary 

Approximately 350 people attended an open house on October 20, 2003 at the Sunflower 

Village Center – 9401 North Sunflower Park Drive. Blank aerial maps were displayed 

and project team members explained the overall project concept to individuals and small 

groups. Comment forms were provided asking the participants to record any comments or 

ask any questions. Notifications were mailed to approximately 15,000 residents that 

reside within a few miles of the project area, including residents in Continental Ranch, 

Sunflower, Dove Mountain, and communities east of I-10. Newspaper advertisements 

were placed in the October 5, 2003, Sunday Arizona Daily Star and the weekly 

Northwest Explorer newspapers on October 8, 2003. A summary of comments received 

and advertisements for the meeting may be found in Appendix A. 

Comment: Construct the TI immediately to relieve Cortaro Road and Silverbell Road (45 

comments) 

Response: This project would utilize federal funds and must follow the federal process; 

therefore, final design may not proceed until after the environmental documentation is 

completed. 

Comment: Provide grade-separation at the railroad (24 comments) 

Response: A grade-separated railroad crossing is part of the proposed improvements 



5-5 





Comment: Concerns about increases in traffic noise (19 comments) 

Response: The traffic noise analysis determined that future traffic noise levels in the area 

would increase and mitigation has been recommended (see Chapter 4, Noise Section, 

page 4-49). 

Comment: Questions about future traffic signals (11 comments) 

Response: The traffic report recommended future traffic signals at the intersections of 

Twin Peaks Road with Silverbell Road, Coachline Boulevard, Access Road, eastbound 

and westbound I-10 frontage roads, and El Camino de Mañana/Linda Vista Boulevard 

(see Chapter 3, Proposed Intersection Improvements, page 3-17). 

Comment: Concerns about connections and effects to other roadways (11 comments) 

Response: Connections to other roadways and the effects to other roadways were 

considered in Chapter 2, Connectivity Section, page 2-6. 

Comment: Concerns about increased traffic on Twin Peaks Road (10 comments) 

Response: Because of the increase in traffic volumes predicted in the traffic report, a 

number of improvements related to traffic signals, shared use paths, and other 

improvements are proposed as a part of the preferred alternative (see Chapter 3, 

Preferred Alternative, page 3-11). 

Comment: Concerns about speeds on Twin Peaks Road (6 comments) 

Response: No changes to the speed limits along the existing section of Twin Peaks Road 

are proposed. The posted speed limit on Twin Peaks Road over the Santa Cruz River 

would be 45 miles per hour. 

Comment: Concerns about safety of children attending Twin Peaks Elementary School (4 

comments) 








Comment: Concerns about CFPO and wildlife movements (4 comments) 

Response: As discussed in the Biological Resources section of Chapter 4 (page 4-25), the 

analysis conducted for the preferred alternative determined that the proposed action may 

affect, but is not likely to adversely affect the CFPO or its habitat due to the project 

design and mitigation measures that would be implemented as a part of this project. 

Comment: Questions about funding (4 comments) 

Response: A combination of federal and local funds would be used on this project. 



5-6 




Comment: Concerns about property values after the project (3 comments) 

Response: It is anticipated that greater access to I-10 and areas east of the Santa Cruz 

River would enhance the area’s desirability and value. 

Comment: Concerns about conflicts/coordination with other projects (3 comments) 

Response: Relationships with other projects were considered and are addressed in 

Chapter 2, Conformance with Regulations, Land Use Plans, and Other Plans, page 2-7. 

Comment: Concerns/questions about changes in land uses/zoning (3 comments) 

Response: This project proposes no changes to land use or zoning within the project 

area. Although some changes in land use or zoning may occur, these changes would be 

under authority of the Town of Marana or Pima County (near the proposed Twin Peaks 

Road TI). 

Comment: Concerns about bicycle facilities and connections (2 comments) 

Response: Pedestrian and bicycle facilities are included in this project (see Chapter 3, 

Proposed Bicycle and Pedestrian Facilities, page 3-20). 

Comment: Concerns about widening Twin Peaks Road (2 comments) 

Response: The project proposes no widening of the existing portion of Twin Peaks Road 


Comment: Concerns about visual impacts (1 comment) 

Response: A visual impacts analysis was completed for this project (see Chapter 4, 

Visual Resources, page 4-41). 

Comment: Concerns about increased traffic through neighborhoods (1 comment) 

Response: Traffic volume increases have been predicted on Twin Peaks Road and 

Coachline Road as a result of the project, but increases in traffic on neighborhood streets 

are not anticipated. Issues associated with unanticipated impacts from the project would 

be addressed by the Town of Marana through established processes and procedures. 

Comment: Concerns about truck traffic in area (1 comment) 

Response: An increase in trucks to 2 percent of the total traffic volume along Twin Peaks 

Road was predicted by the traffic report. 

Comment: Concerns about stormwater runoff (1 comment) 

Response: The drainage study recommended a number of drainage improvements in the 

area (see Chapter 3, Proposed Drainage Improvements, page 3-22). 

Comment: Concerns about utilities (1 comment) 

Response: Utilities have been contacted and are participating in the project. Impacts to 

utilities are discussed in Chapter 4, Utilities and Railroad, page 4-97). 

Comment: Questions about phasing of construction (1 comment) 

Response: It is likely that the project would be phased, but phasing would be developed 

as a part of final design. 



5-7 




Comment: Concerns about amenities – park facilities (1 comment) 

Response: Project amenities are discussed in Chapter 3, Preferred Alternative, page 3- 

11). 

Comment: Expressed desire to receive information from website (1 comment) 

Response: The Town intends to establish a website for this project, but one has not yet 

been established. 

During the initial public information meeting, concerns were expressed regarding the 

safety of children attending Twin Peaks Elementary School. As a result, the Town of 

Marana chose Twin Peaks Elementary School as their initial Safe Routes to School 

program and a “Safe Routes to School” committee was formed. The committee consisted 

of representatives from the Town of Marana’s Engineering staff, Twin Peaks Elementary 

School staff (the Principal and a teacher), a parent of a student at Twin Peaks Elementary 

School, the Marana Unified School District’s Facilities and Transportation Department, 

the Marana Police Department, and an engineering consultant. The committee 

recommended the construction of a 4,500-foot long, 14-foot wide shared use path along 

the south side of Twin Peaks Road from Silverbell Road to Coachline Boulevard and 

along Coachline Boulevard from Twin Peaks Road approximately 725 feet to the south. 

The shared use path was discussed subsequently with the Town of Marana’s Parks and 

Recreation Department and nearby homeowners associations. As the design of the shared 

use path advances, an open house would be held to solicit additional input from the 

community. The Town participated also in a School Safety Day held at Twin Peaks 

Elementary School as part of the educational efforts initiated by the Town. Although the 

Twin Peaks Road TI project does not provide funding for this shared use path, the social, 

economic, and environmental effects of this path are addressed within this document to 

increase the probability of the grant application’s success. 

Public Information Open House #2 - Comments and Response Summary 

Approximately 135 people attended an open house on March 22, 2004 at Twin Peaks 

Elementary School, 7995 W. Twin Peaks Road. A presentation on the status of the 

project, project schedule, and Twin Peaks Road TI location alternatives was given at 7:00 

p.m. The project team was available before and after the presentation to answer questions 

and receive comments from open house participants. Comment forms were available for 

participants to record any comments or ask any questions. The public was asked 

specifically to comment on the three Twin Peaks Road TI alignment alternatives 

presented. The most common comment, as it was in the first public information meeting, 

was that the TI should be constructed as quickly as possible. Notifications were mailed to 

approximately 700 residents, businesses, and government agency personnel who are 

stakeholders in the project or who had expressed interest in the project. Newspaper 

advertisements were placed in the March 7, 2004, Sunday Arizona Daily Star and the 

weekly Northwest Explorer newspapers on March 10, 2004. The advertisements for the 

meeting may be found in Appendix A. 



5-8 




Comment: Preference expressed for the center alternative (18 comments) 

Response: The center alignment was selected as the preferred alignment (see Chapter 3, 

Alternative TI Alignments, page 3-6) 

Comment: Preference expressed for the south alternative (12 comments) 



Comment: Concerns about increases in traffic noise (5 comments) 

Response: The traffic noise analysis determined that future traffic noise levels in the area 

would increase and mitigation has been recommended (see Chapter 4, Noise Section, 

page 4-49). 

Comment: Provide an intermodal center (3 comments) 

Response: An intermodal center is not proposed as a part of the preferred alternative 

because of the additional project costs and because there are no current plans to 

increase mass transit into the area.. 

Comment: Questions about future traffic signals (3 comments) 

Response: The traffic report recommended future traffic signals at the intersections of 

Twin Peaks Road with Silverbell Road, Coachline Boulevard, Access Road, eastbound 

and westbound I-10 frontage roads, and El Camino de Mañana/Linda Vista Boulevard 

(see Chapter 3, Proposed Intersection Improvements, page 3-17). 

Comment: Questions about funding (3 comments) 

Response: A combination of federal and local funds would be used on this project. 

Comment: Concerns about lighting (3 comments) 

Response: New intersection lighting would be provided at all signalized intersections 

within the study area (see Chapter 3, Proposed Lighting Improvements, page 3-20). 

Comment: Concerns about safety of children attending Twin Peaks Elementary School (2 

comments) 








Comment: Preference expressed for the north alternative (2 comments) 





5-9 




Comment: Questions about phasing of construction (2 comment) 

Response: It is likely that the project would be phased, but phasing would be developed 

as a part of final design. 

Comment: Question about estimated costs of the alternatives (2 comments) 

Response: Planning level costs were developed for each of the alignment alternatives. 

The center alignment was the lowest cost alternative. 

Comment: Question about design features of I-10 on and off ramps (2 comments) 

Response: I-10 ramp and frontage road improvements are discussed in Chapter 3, 

Preferred Alternative, page 3-11. 

Comment: Concerns/questions about changes in land uses/zoning (2 comments) 

Response: This project proposes no changes to land use or zoning within the project 

area. Although some changes in land use or zoning may occur, these changes would be 

under authority of the Town of Marana or Pima County (near the proposed Twin Peaks 

Road TI). 

Comment: Expressed desire for decorative features for the improvements (2 comments) 

Response: Preliminary recommendations have been made for project features and 

amenities (see Chapter 4, Visual Resources, page 4-41), but most would be developed 

during final design. 

Comment: Concerns about increased traffic on Twin Peaks Road (2 comments) 

Response: Because of the increase in traffic volumes predicted in the traffic report, a 

number of improvements related to traffic signals, shared use paths, and other 

improvements are proposed as a part of the preferred alternative (see Chapter 3, 

Preferred Alternative, page 3-11). 

Comment: Compliment on efforts to contact the public (1 comment) 

Response: The project team appreciates the comment. 

Comment: Question about maximum height of bridge for alternatives (1 comment) 

Response: The bridges over the Santa Cruz River would be approximately 20 feet above 

the low flow channel of the Santa Cruz River. 

Comment: Save as much existing vegetation as possible (1 comment) 

Response: Vegetation removal is proposed to be as little as needed to construct the 

proposed improvements. For that vegetation that is removed, a revegetation plan would 

be developed (see Chapter 4, Biological Resources, page 4-25). 

Comment: Concerns about conflicts/coordination with other projects (1 comment) 

Response: Relationships with other projects were considered and are addressed in 

Chapter 2, Conformance with Regulations, Land Use Plans, and Other Plans, page 2-7. 

Comment: Concerns about the expense of removing the former portion of El Camino de 

Mañana (1 comment) 







Response: The at-grade railroad crossing with El Camino de Mañana and the 

intersection with the I-10 westbound frontage road would be removed, but other 

segments of the road, east of the UPRR would be retained for access to the TEP 

transmission lines and towers and to provide access to adjacent properties. Although a 

portion of the existing El Camino de Mañana north of its existing intersection with Linda 

Vista Boulevard would be abandoned, final design would determine how much of the 

roadway would be removed. 

Comment: Concerns about effects to businesses near TI (1 comment) 

Response: Impacts to businesses are discussed in Chapter 4, Land Use on page 4-1 and 

Relocations/Displacements on page 4-83, and Secondary Impacts on page 4-101. 

Comment: Preference for the main cross road to have a single name (1 comment) 

Response: The project proposes that Twin Peaks Road be extended across I-10 to the 

intersection with Linda Vista Boulevard. North of Linda Vista Boulevard, the road would 

be called El Camino de Mañana, as it is today. 

Comment: Concerns about speeds on Twin Peaks Road (1 comments) 

Response: No changes to the speed limits along the existing section of Twin Peaks Road 

are proposed. The posted speed limit on Twin Peaks Road over the Santa Cruz River 

would be 45 miles per hour. 

Comment: Expressed desire for single point urban interchange (1 comment) 

Response: A single point urban interchange configuration was considered, but was 

rejected because of several operational problems. A tight diamond interchange was 

selected as the preferred alternative (see Chapter 3, Alternative TI Configurations, page 

3-2). 

Comment: Concerns about increased traffic through neighborhoods (1 comment) 

Response: Traffic volume increases have been predicted on Twin Peaks Road and 

Coachline Road as a result of the project, but increases in traffic on neighborhood streets 

are not anticipated. Issues associated with unanticipated impacts from the project would 

be addressed by the Town of Marana through established processes and procedures. 

Comment: Expressed desire to receive information from website (1 comment) 

Response: The Town intends to establish a website for this project, but one has not yet 

been established. 

In addition to meetings with the general public and residential property owners, a number 

of meetings occurred with the affected business community. Because the business owners 

had different concerns (e.g. acquisitions and access) than the residential property owners 

(e.g. noise and traffic), separate meetings were held. This allowed discussion at a greater 

level of detail than would be possible in general public meetings. Although numerous 

meetings have occurred over the course of the project, the larger of these meetings are 

summarized below. Most of the comments received from the business community in the 

project area have involved R/W acquisitions, access limitations to the frontage road, timing 

of R/W acquisitions and construction, business visibility from the interstate, and billboard 



5-11 




locations. More complete descriptions of these meetings and summaries of comments may 

be found in Appendix A. 

• September 5, 2003 - Met with individual business and property owners along I-10 

at Days Inn Conference Room (7 meetings) to introduce the project and solicit 

early concerns. 

• March 12, 2004- Met with business and property owners along I-10 at Marana 

Development Services (15 meetings) to present and receive comments on the 

alternatives. 

Hearing 

The Draft EA would be made available for public review and comment. To facilitate public 

involvement, a public hearing to explain the project and its environmental consequences 

would be held in the study area. Comments received at the public hearing and during the 

30-day review and comment period would be incorporated into the Final Environmental 

Assessment (FEA) prepared for this project. The FEA would be used to determine the final 

environmental impacts for the project. 

Other On-Going Activities 

Throughout the final design and construction processes, efforts to inform and involve the 

community and businesses would be continued. A series of community meetings would be 

conducted at appropriate phases throughout the project. These meetings would inform the 

community of upcoming construction activities and the possible affects of these activities 

on the community and would offer the opportunity for the community and businesses to 

provide suggestions or comments that may minimize these affects. The meetings would be 

advertised in the same manner as the public information meetings for this project. Special 

efforts would be made to keep emergency services personnel informed of construction 

activities. Construction information would be available to the general public through 

regular briefings and information releases to newspapers, radio, and television. 

Conclusion 

To ensure that the public contributed to this study and had full access to study results, a 

number of public meetings and outreach efforts occurred and technical committees were 

formed. The design of the preferred alternative has been modified to address some of the 

concerns that have resulted from these public involvement efforts. After circulation of the 

Draft EA, a public hearing to explain the project and its environmental consequences 

would be held in the study area. Comments received would be addressed and incorporated 

into the FEA. A series of community meetings would be conducted at appropriate phases 

throughout the remainder of the proposed project. Construction information would be 

available to the general public through regular briefings and information releases. 



5-12 



Conclusion October 2005 

CHAPTER 6: CONCLUSION 

The environmental impacts of the preferred alternative and the no build alternative were 

evaluated based on both the context of the effects on the project area and the intensity or 

severity of impacts as defined in the CEQ Regulations. Table 6-1 summarizes the 

environmental impacts. 

Table 6-1. Summary of Environmental Assessment 

Environmental 

Result of No Build Result of Preferred 

Consideration 

Alternative evaluation Alternative evaluation 

Land use No impacts Short-term minor negative 

impacts 

Long-term minor negative 

Land resources 

• Topography 

• Soils 

• Geologic setting/ 

mineral resources 

• Agriculture 

Water resources 

• Surface water 

• Ground water 

Water quality 

• Floodplains 

• Section 404/401 

• AZPDES/SWPPP 

• Sole source aquifer 

Biological resources 

• Wildlife 

• Threatened/ 

endangered species 

• Arizona wildlife of 

concern 

• Critical habitat 

• Vegetation, riparian 

habitat, wetlands 

• Invasive species 



impacts 

No impacts Short-term minor negative 

impacts 


impacts 

Short-term moderate 

negative impacts 

Long-term moderate 


Short-term minor negative 

impacts 


beneficial impacts 


impacts 

No long-term negative 

impacts 


impacts 

No long-term negative 

impacts 

6-1 



Conclusion October 2005 



Table 6-1. Summary of Environmental Assessment 

Environmental 

Result of No Build Result of Preferred 

Consideration 

Alternative evaluation Alternative evaluation 

Visual resources No impacts Short-term moderate 



Air quality Long-term minor negative 

impacts 

Noise Long-term minor negative 

impacts 

6-2 



impacts 

Long-term minor beneficial 

impacts 

Short-term moderate 



impacts 

Hazardous materials No impacts Short-term minor negative 

impacts 

Long-term minor beneficial 

impacts 

Cultural resources No impacts Short-term minor negative 

impacts 


Socioeconomics Long-term moderate 


Section 6(f)/Section 4(f) Long-term minor negative 

impacts 

impacts 


impacts 




impacts 



Utilities No impacts Short-term moderate 


No long-term impacts 

Secondary impacts Long-term minor beneficial 

impacts 

Cumulative impacts Long-term minor negative 

impacts 



Project Preparers and Contributors October 2005 

CHAPTER 7: PROJECT PREPARERS AND 

CONTRIBUTORS 

Federal Highway Administration 

Stephen Thomas Environmental Program Manager 

Town of Marana 

Harvey Gill Interim Director of Public works 

Kevin Thornton, PE Project Manager 

Farhad Moghimi 

Arizona Department of Transportation 

Melissa Maiefski Environmental & Enhancement Group 

Laurel Parker Project Manager, Tucson District 

Kae Neustadt Environmental & Enhancement Group 

Ed Green Environmental & Enhancement Group 

Fred Garcia Environmental & Enhancement Group 

Laura Tsosie Environmental & Enhancement Group 

URS Corporation 

Scott Stapp Environmental Assessment Manager 

William Dehn, PE Roadway Design 

Eric Sibson, PE Roadway Design 

Gene Rogge, PhD Cultural Resources 

Jean Paul Charpentier Biology 

Barbara Garrison Biology 

Dana Strength Geology and Water Resources 

Mary Burke Hazardous Materials 

Michael Pegnam, PE Geotechnical 

Jaime Wood Land Use and Socioeconomics 

Kimley-Horn and Associates, Inc. 

David Perkins, PE, PTOE Traffic Analysis 

Scott Beck, PE 

Kaneen Advertising and Public Relations, Inc. 

Nanette Pageau Public Involvement 

Carol Oaks 

Entranco 

Mike Bertram, PE Drainage 

Edie Griffith-Mettey, PE 

Wheat Scharf Associates 

Liba Wheat, RLA Visual Resources/Landscaping 

Laura Mielcarek, RLA 

JE Fuller Hydrology and Geomorphology 

John Wallace, PE Hydraulics/Hydrology 



7-1 



Bibliography October 2005 

CHAPTER 8: BIBLIOGRAPHY 

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1996. 

Anderson, S. R. Cenozoic Stratigraphy and Geologic History of the Tucson Basin, Pima 

County, Arizona. U.S. Geological Survey Water-Resources Investigations Report 87- 

4190. 1987. 

Arizona Department of Transportation. Noise Abatement Policy for Federal Aid Projects. 

March 21, 2000. 

Arizona Department of Transportation. Roadway Design Guidelines. February 2004. 

Arizona Department of Transportation. Standard Specifications for Road and Bridge 

Construction. 2002. 

Bureau of Land Management. Visual Resource Management Manual: 8400 BLM Standards. 

March 1981. 

Davidson, E.S. Geohydrology and Water Resources of the Tucson Basin, Arizona. U.S. 

Geological Survey Water-Supply Paper 1939-E. 1973. 

Euge, Kenneth M. and Schell, R. G. Seismic Maps for Arizona, Final Report: Prepared for 

the Arizona Department of Transportation, Report Number: FHWA-AZ92-344. 1992. 

Federal Emergency Management Agency. Flood Insurance Rate Maps. FIRM 0419C1015K 

and 0419C1605K D. effective date February 8, 1999. 

Federal Highway Administration, Addressing Environmental Justice in the Environmental 

Assessment and Environmental Impact Statement, September 1998. 

Federal Highway Administration. Environmental Guidebook. 

http://www.environment.fhwa.dot.gov/guidebook/index.htm. 

Federal Highway Administration, FHWA Technical Advisory T 6640.8A. 1987. 

Federal Highway Administration. Procedures for the Abatement of Highway Traffic and 

Construction Noise, 23 CFR 772. 

Federal Highway Administration. Visual Impact Assessment for Highway Projects. March 

1981. 

Institute of Transportation Engineers. A Toolbox For Alleviating Traffic Congestion And 

Enhancing Mobility. ISBN 0-935403-12-4. 1996. 

JHK & Associates. Change of Freeway Access Report, I-10 Corridor Improvements General 

Plan Ruthrauff Road to Tangerine Road, Contract Number 87-38, Project Number 

IR-10-4(102)PE, ADOT TRACS Number HO15101D. December 1991. 



8-1 




JHK & Associates. Final Environmental Assessment I-10 Corridor Improvements General 

Plan Ruthrauff Road to Tangerine Road Contract Number 87-38, Project Number IR- 

10-4(102)PE, ADOT TRACS Number H015101D. October 20, 1993. 

JHK & Associates. I-10 Corridor Improvements General Plan Ruthrauff Road to Tangerine 

Road, Contract Number 87-38, Project Number IR-10-4(102)PE, ADOT TRACS 

Number HO15101D, Design Concept Study. January 1990. 



Number HO15101D, Noise Analysis Report. October 1991. 



Number HO15101D. 1993. 

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I-10 Twin Peaks Traffic Interchange, Environmental Assessment

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