I-10 Twin Peaks Traffic Interchange, Environmental Assessment

Affected Environment and Environmental Impacts October 2005
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
Existing Conditions
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.
Interstate 10 Traffic Interchange at
Twin Peaks/Linda Vista
4-22
Project No.: NH-010-D (AIW)
TRACS No.: 10 PM 236 H5838 01D