FEIS Summary - Knik Arm Bridge and Toll Authority

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Knik Arm Crossing Final EIS Summary The preliminary design includes plans for potential future expansion (Phase 2) when traffic volumes would warrant its completion. In the Mat-Su, the project’s controlled-access right-of-way 1 would be large enough to expand to two lanes in each direction, including accommodations for a pathway. Proposed right-of-way (Phase: 1 and 2), typically 400 to 450 feet wide Future expansion (Phase 2) Proposed Mat-Su roadway (Phase 1) Future expansion (Phase 2) 1 a designation that allows intersecting roads or driveways at only limited points to promote safety and travel efficiency Future pathway Future two-way frontage road Future divided roadway expansion Future two-way frontage road Point MacKenzie Road Alternative Sources: Imagery from SMB June 2004 MSB GIS, HDR Inc. 0 0.5 1 Mile Key Costs and Impacts for Mat-Su Approach Alternatives Costs Construction Design, engineering, and construction administration Contingency Total (by phase) (Note that Phase 2 would include future build-out of project.) Point MacKenzie Road Alternative Phase 1: $33.7M Phase 2: 31.2M Phase 1: 4.9M Phase 2: 4.5M Phase 1: 7.0M Phase 2: 11.3M Phase 1: 45.6M Phase 2: 47.0M Northern Access Alternative (Recommended Alternative) Phase 1: $34.2M Phase 2: 28.7M Phase 1: 5.0M Phase 2: 4.2M Phase 1: 7.2M Phase 2: 10.3M Phase 1: 46.4M Phase 2: 43.2M Controlled-Access Right-of-way (ROW): A designation that allows intersecting roads or driveways at only limited points to promote safety and travel efficiency. ROW costs $0.8M $0.6M Affected land parcels 30 28 ROW acquisitions/relocations Section 4(f) Recreational Properties Businesses: 0 Residences: 0 Businesses: 0 Residences: 0 Point MacKenzie Recreational Trailhead 0.55 acre of trailhead used 0 acres of trailhead used Wetlands Forested 14.2 acres 9.7 acres Sedge and grass 17.3 acres 15.5 acres Scrub/shrub 5.9 acres 3.3 acres Total 37.4 acres 28.5 acres Northern Access Alternative Sources: Imagery from SMB June 2004 MSB GIS, HDR Inc. 0 0.5 1 Mile Exhibit S-15 Mat-Su Side Alternatives Because many impacts are relatively equal, FHWA prefers the Northern Access Alternative for its consistency with Mat-Su Borough and Port MacKenzie planning efforts. As part of the Recommended Alternative, the Northern Access Alternative: • will remove through-traffic from Port MacKenzie • will be more conducive to Port MacKenzie expansion plans Exhibit S-15. Mat-Su Side Alternatives S-32
The preliminary design includes plans for potential future expansion (Phase 2) when traffic volumes would warrant its completion. For the crossing, two more lanes of bridge decking could be added, without having to install additional piers. This section rendering gives an idea of what the bridge might look like. Final bridge design has yet to be determined. Future expansion (Phase 2) Knik Arm Crossing Final EIS Summary Proposed crossing (Phase 1) Mat‐Su side Mat-Su ~8,200 feet 50 foot clearance 250 feet Anchorage side Anchorage Navigation channel Add two lanes and pathway for future expansion 14,000-foot Bridge Alternative 1 2 Key Costs and Impacts for Bridge Alternatives 8,200-foot Bridge Alternative North North Sources: Imagery from SMB June 2004 MSB GIS, HDR Inc. Anchorage side 0 0.25 0.5 Mile 14,000-foot bridge approach 1 Costs Construction Design, engineering, and construction administration Contingency Total (by phase) (Note that Phase 2 includes future build-out of project through 2030) In-Water Construction Methods 14,000-foot Bridge Alternative 1 Phase 1: $478.8M Phase 2: 174.3M Phase 1: 69.4M Phase 2: 25.3M Phase 1: 93.2M Phase 2: 63.1M Phase 1: 641.4M Phase 2: 262.7M Barges and temporary construction trestles in mud flats (would require fill) 8,200-foot Bridge Alternative (Recommended Alternative) Barges only Phase 1: $319.3M Phase 2: 85.9M Phase 1: 46.3M Phase 2: 12.5M Phase 1: 61.2M Phase 2: 31.1M Phase 1: 426.8M Phase 2: 129.5M Construction Time 3 construction seasons 2 construction seasons Number of Piers 66–76 piers 33 piers Marine Fill ~ 45 acres total ~ 90 acres total Beluga Whale (Pile driving is a key concern because pile-driving noise will adversely affect belugas most.) Essential Fish Habitat Estimated Sedimentation (silt accumulation over time around bridge approaches) • 440–508 hours pile-driving noise • Less fill in habitat • Subtidal waters ~ 0 acres filled • Estuarine shores and mud flats: ~ 45 acres would be filled • 220 hours pile-driving noise • More fill in habitat • Subtidal waters ~ 8 acres filled • Estuarine shores and mud flats: ~ 82 acres would be filled 20 acres around abutments 260 acres around abutments North North Sources: Imagery from SMB June 2004 MSB GIS, HDR Inc. 0 0.25 0.5 Mile Anchorage side 8,200-foot bridge approach Exhibit S-16 The Crossing Alternatives Knik Arm The 8,200-foot Bridge is part of the Recommended Alternative because: • installation of fewer piers will reduce in-water noise and other construction impacts on species inhabiting Knik Arm waters within the Project Area • shorter construction time (two construction seasons will be required) • construction cost ($426.8M total will be reasonable) Knik Arm 1 The 14,000-foot Bridge Alternative was found to not be financially feasible and did not meet stated purpose and need criteria; however, this alternative was carried forward solely for comparative evaluation based on requests from environmental resource and permitting agencies. 2 Only one or the other bridge approach alternative would be constructed—i.e., the portion of the “Y” corresponding to each respective approach alternative. Exhibit S-16 The Crossing Alternatives S-33
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 31: Knik Arm Crossing Final EIS Summary
Page 35 and 36: Summary Initial Construction (Phase

FEIS Summary - Knik Arm Bridge and Toll Authority

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