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

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) EvaluationWarwick Avenue at Squantum Drive on the east. Fully Relocated Airport Road would impact Wetland A2(1.1 acres) and Wetland I (0.5 acres).The use of a flyover structure was investigated to avoid impact at Wetland I in the vicinity of Post Road.Preliminary cost estimates were approximately $4 million to avoid 0.5 acres of wetland impact. The flyover isnot practicable based on cost. An alternative roadway alignment to avoid impacts to Wetland A2 was alsoinvestigated. This alignment (north of Wetland A2) would have significant adverse impacts to residentialneighborhoods and would intersect Warwick Avenue well north of Squantum Drive. This avoidance alternativeis not practicable because of the magnitude of the residential impacts and because it would create undesirabletraffic conditions on Warwick Avenue.Other unavoidable impacts occur at Warwick Avenue which crosses Spring Green Pond on fill (Wetland P). Anadditional travel lane would be added to Warwick Avenue in this location. There are wetlands at the base ofslope on either side of Warwick Avenue such that impact to wetland cannot be avoided. The small impact atWetland A3 is required to build a stormwater outfall from Fully Relocated Airport Road and cannot be avoidedas other discharge points are not available.Under Alternative B4, the Fully Relocated Airport Road is not proposed, thereby avoiding any associatedwetlands impacts.5.10.8.2 MinimizationImpacts to wetlands have been minimized through modifications to the design of Alternatives B2 and B4, asdescribed below. Additional minimization measures may be feasible and will be evaluated once the PreferredAlternative moves into the final design phase.Runway 34As presented in the DEIS, Alternatives B2 and B4 both would minimize wetland filling by installing EMAS atthe Runway 34 End to reduce the FAA-required minimum length of the RSAs from 1,000 feet to 600 feet.Prior to incorporating further avoidance and minimization measures described for Alternative B2, the impact towetlands at the Runway 34 End was estimated at 4.2 acres. This has been reduced to 2.5 acres underAlternative B2 mostly through avoidance measures that have already been described. Similarly forAlternative B4, impacts to these wetlands have been reduced through the alternatives analysis process from7.3 acres presented in the DEIS to 5.0 acres currently proposed.Due to the use of an end-fire navigational system at Runway 34 as described under avoidance, the side slopesalong the runway can be steepened beginning at the edge of the RSA. This in turn allowed the Perimeter Roadto be shifted closer to the side of Runway 34. This shift brought the Perimeter Road within the glide slopeantenna signal zone so the road was lowered to prevent vehicles from interfering with the signal. Impacts toWetland A8 from the glide slope area were reduced from 1.8 acres to 0.1 acres from the combination ofavoidance and minimization measures.Chapter 5 - Environmental Consequences 5-207 July 2011\\mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH05_Environmental_Cons_JUL_2011.doc