FEIS Summary - Knik Arm Bridge and Toll Authority

More documents

Recommendations

Info

Knik Arm Crossing Final EIS Summary Exhibit S-24. Mitigation Measures and Commitments for the Recommended Alternative (continued) EIS section Environmental Conseq uences section title 4.8 Impacts on the Natural Environment Mitigation Measures and Commitments 4.8.1 Impacts on Surface Water Resources Water Bodies (lakes, streams, ponds) and Water Quality KABATA or its contractors will develop an Erosion and Sediment Control Plan (ESCP) to meet Alaska Department of Environmental Conservation (ADEC) and USEPA requirements of the Clean Water Act. The ESCP will be prepared by a registered engineer and included in the contract plan set. • The ESCP will become the basis of the USEPA Notice of Intent and the contractor’s SWPPP, which will be implemented during project construction to minimize soil disturbance. • The ESCP will direct contractors to reduce construction impacts, particularly those impacts that would result in destabilization of adjacent slopes and in possible siltation. The following mitigation measures will be undertaken to limit sediment disturbance from construction activities: • BMP erosion and sediment control measures, such as furrow ditches, check dams, and detention basins, will be used, as appropriate. • To protect critical areas around freshwater bodies and wetlands sites from potential exposure to sediment plumes, appropriate BMPs will be employed that allow passage of water but capture sediment. • Erosion will be reduced during and after construction by seeding cut and fill slopes as soon as practically possible with both fast-growing annual species (to establish a root mass) and with native species (for long-term growth and soil stabilization). The contractor shall comply with USEPA’s General Permit for Stormwater Discharges from Construction Activities, including preparing and implementing a detailed SWPPP. The SWPPP will be prepared by a registered engineer to direct the contractors’ efforts to minimize construction impacts on water quality and it would be implemented and adjusted during project construction. The plan will describe BMPs developed in accordance with ADOT&PF’s Alaska Storm Water Pollution Prevention Plan Guide and USEPA’s Stormwater Management for Construction Activities: Developing Pollution and Prevention Plans and Best Management Practices. Impacts to water quality will also be minimized through the use of BMPs that minimize erosion, temporary water quality impacts from construction activities, and the introduction of suspended sediment and siltation. BMPs that will be employed include: • Coarse rock rubble to stabilize toes of slopes at ponds and stream crossings to prevent the erosion of fine-grained material into adjacent waters and wetlands. • Roadside swales designed to detain surface water to allow sediment-laden water to clear before being discharged to adjacent wetlands and waters. Construction-related BMPs that will be employed include: • Clearly demarcating clearing limits prior to construction to ensure impacts are confined within the project footprint near water bodies and wetlands and within 20 feet of the footprint in other areas. • Performing regular visual inspections of all slopes to monitor for slope erosion. • Locating all fueling, and equipment-servicing operations at least 100 feet away from all streams and wetlands. • Having spill-response equipment readily available and ensuring that construction personnel are trained in spill response to contain accidental leaks of oil or fuel from construction equipment. All roads will be designed to maintain existing surface water courses and will incorporate grass-lined ditches and swales. In areas where curb-and-gutter storm drains would be required, enclosed collection systems will be incorporated to minimize the effects of runoff. Alterations to surface drainage and hydrology that could adversely affect nearby water bodies will be avoided or minimized through incorporation of appropriately designed, sized, and placed culverts under the roadway. KABATA will hold meetings with the construction contractor and agencies to ensure implementation of mitigation commitments. The drainage design of the road through Government Hill will incorporate all feasible measures to detain water on site or in other designated areas and to avoid direct routing of stormwater to creeks. The KAC project will incorporate a clear-span structure to cross Ship Creek. All required permits and agency approvals will be obtained prior to construction, and any permit stipulations will be incorporated into the construction contract specifications. All applicable state and federal permit conditions will be adhered to throughout the construction stage. Marine Hydrology In 2007, KABATA conducted supplemental field studies, reconfigured the hydrologic model, and gathered additional information on Knik Arm marine hydrology. This information was submitted to the USACE. KABATA will continue to coordinate with the USACE during the design and permitting phase of the project. Exhibit S-24 Mitigation Measures and Committments (continued on next page) S-56
Knik Arm Crossing Final EIS Summary Exhibit S-24. Mitigation Measures and Commitments for the Recommended Alternative (continued) EIS section Environmental Conseq uences section title Mitigation Measures and Commitments 4.8.2 Impacts on Wetlands In compliance with Section 404 of the Clean Water Act, the following actions will be taken to avoid and minimize potential impacts to wetlands in the project corridor: 1. Design the project to avoid impacts The preliminary design of the KAC Project largely avoids impacts to wetlands by: Incorporating the existing road prism of the Port MacKenzie Road section of the Northern Access Alternative. Locating the northernmost wetland crossing at the wetland’s narrowest point. 2. Incorporate measures to minimize adverse impacts Minimization of adverse impacts will be achieved by: Using properly sized and designed culverts in appropriate locations to maintain natural flow patterns for surface water to ensure that timing and inflows to adjacent wetlands and waters will be retained. 3. Restore sites that must be temporarily affected by the project To protect hydrologic and water quality functions that will be temporarily disturbed but not destroyed by implementation of the KAC Project, affected wetland areas will be recontoured and revegetated with plant species indigenous to the Cook Inlet area. 4. Compensate for unavoidable impacts through preservation, restoration, or creation of wetlands In areas where wetlands will be filled or fragmented and functions lost, the Anchorage Debit/Credit Methodology will be used to determine the appropriate level of compensation needed to offset the wetland loss. As design progresses, KABATA will work with USACE to determine the area of wetlands adversely affected, the appropriate relative ecological value (REV) of affected wetlands, and compensation to be provided to the Great Land Trust or appropriate organizations. All required permits and agency approvals will be obtained prior to construction, and any permit stipulations will be incorporated into the contract specifications. 4.8.3 Impacts on Floodplains None 4.8.4 Impacts on Wild and Scenic Rivers None 4.8.5 Impacts on Coastal Barriers None 4.8.6 Impacts on the Coastal Zone 4.8.7 Impacts on Habitats KAC Project will include construction in Alaska’s coastal zone and will be consistent with the Alaska Coastal Management Program and both the Anchorage and Mat Su Borough Coastal Management Plans (CMPs). Conditions of the Alaska Department of Natural Resources (ADNR) Consistency Determination will be adhered to throughout the project. 4.8.7.1 Marine Habitat See mitigation measures listed in this table under Essential Fish Habitat. 4.8.7.2 Freshwater Habitat See mitigation measures listed in this table under Water Bodies (lakes, streams, ponds) and Water Quality. 4.8.7.3 Terrestrial Habitats To protect the integrity of the natural plant communities and to prevent the introduction of invasive species, the following BMPs will be incorporated into construction activities: • Minimize the removal or disturbance of roadside vegetation during construction. • Minimize contact with roadside sources of weed seed that could be transported to other areas. • Use only certified weed-free straw and mulch or weed-free fiber roll barriers or sediment logs as part of the BMPs employed for erosion control. • When conducting project-related revegetation, use only plant species native to Southcentral Alaska, except that noninvasive annual grasses may be used to provide initial soil cover; only seed meeting certified standards pursuant to 11 Alaska Administrative Code (AAC) 34.075 will be used. • Final project design will seek to minimize direct impacts on vegetation by defining narrow clearing limits (except in areas of known high-moose traffic) and using already-disturbed areas when possible. Exhibit S-24 Mitigation Measures and Committments 4.8.8 Impacts on Wildlife 4.8.8.1 Marine Invertebrates None (continued on next page) S-57
Page 1 and 2:
Knik Arm Crossing Final Environment
Page 3 and 4:
Exhibit S‐1. Final EIS Document O
Page 5 and 6: Knik Arm Crossing Final EIS Summary
Page 15 and 16: Exhibit S‐22. Reasons for Preferr
Page 17 and 18: Findings, Compliance, and Permits E
Page 25 and 26: ! ! ! ! ! ! ! ! ! ! ! ! Knik Arm Cr
Page 33 and 34: The preliminary design includes pla
Page 35 and 36: Summary Initial Construction (Phase
Page 55: Knik Arm Crossing Final EIS Summary
show all

FEIS Summary - Knik Arm Bridge and Toll Authority

Create successful ePaper yourself

Delete template?

Save as template?