FEIS Summary - Knik Arm Bridge and Toll Authority

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Knik Arm Crossing Final EIS Summary Exhibit S-23 Environmental Impacts Associated with Construction and Operation of the Recommended Alternative (continued) Impact category Impacts on Coastal Zone Direct impacts Construction impacts Indirect impacts Cumulative impacts Impacts on Habitats Direct impacts Marine Habitat None Freshwater Habitat None Northern Access Alternative (Mat-Su Side) Recommended Alternative Southern Alignment Crossing with 8,200-Foot Bridge and Connecting Roadways on Gravel Fill (The Crossing) 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). Development in the Mat-Su Borough will occur in the coastal zone and will be regulated by the Mat-Su Borough CMP. Terrestrial Habitat The project would result in loss of the following terrestrial habitat types: Needleleaf forest: 1 acres Broadleaf forest: 36 acres Mixed needleleaf/broadleaf forest: 398 acres Tall shrub: 14 acres Dry herb: 36 acres Developed: 133 acres Total upland impacts: 618 acres Marine Habitat Placement of bridge piers and placement of fill and armor rock: Fill in estuarine shores and mud flats: 82 acres Fill in subtidal waters: 8 acres Placement of 33 piers Roadway will adversely affect upper intertidal habitat functions by altering ground water discharge (eliminating freshwater seeps located along the bottom of the coastal bluff), eliminating limited wildlife habitat, and deterring wildlife from using the coastal area as a movement corridor. The placement of fill for the abutments will result in permanent loss of subtidal habitat, but will not result in trophic-level effects since this is not a highly productive habitat. Freshwater Habitat N/A Terrestrial Habitat Construction of the Below the Bluff Roadway north of the future POA expansion will result in loss of intertidal habitat used as a terrestrial mammal movement corridor along Knik Arm. Marine Habitat None Erickson Alternative (Anchorage Side) Freshwater Habitat Installation of culverts and the placement of fill will directly affect numerous drainages along the bluff north of the POA and Cherry Hill Ditch. Terrestrial Habitat The project would result in loss of the following terrestrial habitat types: Broadleaf forest: 17 acres Dry herb: 5 acres Developed: 13 acres Total upland impacts: 35 acres (continued on next page) Exhibit S-23 Environmental Impacts Associated with Construction and Operation S-46
Knik Arm Crossing Final EIS Summary Exhibit S-23 Environmental Impacts Associated with Construction and Operation of the Recommended Alternative (continued) Impact category Construction impacts Indirect impacts Cumulative Impacts Marine Habitat None Freshwater Habitat None Northern Access Alternative (Mat-Su Side) Terrestrial Habitat Temporary habitat impacts attributable to equipment working outside the project footprint. Some habitat regrowth would be expected. Habitat functions, including support for wildlife, would be temporarily or permanently lost. Marine Habitat N/A Freshwater Habitat Increased development near water bodies will result in encroachment on riparian areas, additional runoff, increased nutrient loading, fecal coliform contamination, increases in hydrocarbons, and increased extent of impervious surfaces. Reductions in water quantity and quality will occur. Terrestrial Habitat The difference between the No-Action and the KAC Project will result in permanent loss of approximately 14,650 acres of natural upland habitats due to indirect growth: Needleleaf forest: 1,385 acres Broadleaf forest: 9,810 acres Mixed needleleaf/broadleaf forest: 2,500 acres Tall and low shrub: 335 acres Dwarf shrub and related communities: 5 acres Dry or moist herb: 80 acres Wet herb: 65 acres Agriculture: 470 acres Total: 14,650 acres KAC Project will contribute to the general decline in quantity and quality of terrestrial habitat. Recommended Alternative Southern Alignment Crossing with 8,200-Foot Bridge and Connecting Roadways on Gravel Fill (The Crossing) Marine Habitat Staging area: gravel-filled pad on west side of Knik Arm will result in the loss of approximately 3 acres of marine habitat. Because of movement and placement of sediment and rock in shoreline areas, turbidity will increase. Freshwater Habitat N/A Terrestrial Habitat None Marine Habitat The KAC Project will result in total fillet formation (sediment accumulation) of 260 acres on both sides of the approaches. Increased marine use as a result of growth in shipping traffic at Port MacKenzie will adversely affect intertidal and subtidal habitat. Freshwater Habitat N/A Terrestrial Habitat None Marine Habitat None Erickson Alternative (Anchorage Side) Freshwater Habitat Increased sediment runoff Temporary increases in suspended solids, turbidity, and pollutants from construction equipment. Terrestrial Habitat Temporary habitat impacts attributable to equipment working outside the project footprint. Some habitat regrowth would be expected. Habitat functions, including support for wildlife, would be temporarily or permanently lost. Marine Habitat N/A Freshwater Habitat Increased development near water bodies will result in encroachment on riparian areas, additional runoff, increased nutrient loading, fecal coliform contamination, increases in hydrocarbons, and increased extent of impervious surfaces. Reductions in water quantity and quality will occur. Terrestrial Habitat Wildlife displaced may have the opportunity to occupy nearby undeveloped areas, depending on carrying capacity of these areas. (continued on next page) Exhibit S-23 Environmental Impacts Associated with Construction and Operation S-47
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 45: Knik Arm Crossing Final EIS Summary

FEIS Summary - Knik Arm Bridge and Toll Authority

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