T.F. Green Airport Improvement Program - FEIS Chapters - PVD

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) Evaluation5.10.8.1 AvoidanceThroughout the project design, the RIAC and FAA worked to identify project designs that would achieve theproject purpose while avoiding impact to wetlands. During this process several alternatives were designed andassessed to determine if they were practicable.Runway 34There are seven wetlands (A6, A8, A10, A11, A13, A14, and A16) present at the Runway 34 End, includingBuckeye Brook below Warwick Pond and a series of tributaries to Buckeye Brook which flow from west to easttoward the brook. Wetlands next to Runway 34, Taxiway C, and the Perimeter Road are generally bounded byfill slopes used to construct the Airport. Impacts to Wetland A13 south of Runway 34 could be avoided if theentire runway was shifted north so the Runway 34 RSA would not be constructed in a wetland. This scenariowas evaluated in the Level 4 Alternatives Analysis and was found not practicable since this would require PostRoad to be relocated or closed.Alternatives B2 and B4 would impact Wetlands A6, A8, and A11 at the Runway 34 End to relocate Taxiway C aminimum safe distance from the runway, and construct a new Perimeter Road. Impacts associated withTaxiway C and the Perimeter Road are necessary to meet FAA minimum safety distances.Earlier designs for the Runway 34 End in the DEIS included a hold apron west of the Runway 34 End foraircraft awaiting clearance to approach the runway end in preparation for takeoff. These designs also included aPerimeter Road constructed outside of the Runway Object Free Area (ROFA). The hold apron was latereliminated to avoid impacts to Wetland A11 and Tributary A11. Impacts to Wetlands A10 and A13 were furtheravoided in the DEIS by constructing the Perimeter Road through the RSA and ROFA between the Runway 34End and the EMAS bed. Impacts to Wetlands A11 and A6 were also further avoided by routing the PerimeterRoad away from the west side of relocated Taxiway C to the south of these wetlands, mostly through uplandsthat are already cleared along the perimeter security fence.Alternative B2 would shift Runway 16-34 north by 400 feet and would mostly avoid impacts to Wetland A13south of the existing Runway 34 End. This would avoid the requirement to construct the RSA safetyenhancements to the south of the existing runway end into Wetland A13. The use of EMAS at both runwayends, described in Section 5.10.8.2, Minimization, avoids the need to relocate U.S. Route 1 (Post Road) which hadalready been determined to be impracticable. However, it was determined that avoidance of Wetland A13 wasimpracticable due to undesirable socioeconomic impacts created by the relocated Runway 16 RSA. Theseimpacts are further described in Chapter 3, Alternatives Analysis.Alternative B4 was designed to shift Runway 16-34 approximately 100 feet north of its present location. This wasdetermined to be the maximum distance that Runway 16-34 can be shifted away from wetlands at theRunway 34 End and comply with FAA standards at the Runway 16 End while avoiding the requirement todemolish the Airport Plaza building and other undesirable socioeconomic impacts associated with theAlternative B2 design. Similar to Alternative B2, Alternative B4 would avoid further impact to Wetland A11 andTributary A11 by eliminating the hold apron west of the Runway 34 End. Impacts to Wetlands A10 and A13would also be avoided by constructing the Perimeter Road through the RSA and ROFA between the Runway 34Chapter 5 - Environmental Consequences 5-205 July 2011\\mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH05_Environmental_Cons_JUL_2011.doc