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

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) Evaluation5.10.3 MethodologyThis section defines how significant direct, indirect, temporary, and cumulative impacts to wetlands within theStudy Area are identified.5.10.3.1 Direct Impacts MethodologyDirect permanent and temporary wetland impacts include wetland fill, vegetation removal, dredging, andwatercourse relocation or alteration, that result in a loss of existing wetlands area, function and/or value.Temporary impacts involve short-term disturbance to wetlands and waterways during construction.The potential direct impacts to wetlands and waterways were evaluated by overlaying the grading limits ofAlternatives B2 and B4 on base mapping depicting the wetlands and waterways. Impacts associated withvegetation removal in areas where no fill would be placed have not been determined at this time, butalternatives with greater wetland fill generally would have greater impacts associated with vegetation removal.Wetland impacts reported in this FEIS refer to areas where fill would be placed in federal jurisdictionalwetlands, which are referred to as “vegetated wetlands” under the RIDEM Rules.Fill and grading impacts to perimeter and riverbank wetlands, dimensional setbacks from vegetated wetlands,rivers and streams which are only subject to state regulation, have also been calculated for Alternatives B2and B4. These impacts were calculated by first preparing an existing conditions plan depicting perimeter andriverbank wetlands using wetland classifications provided in 2004 in RIDEM correspondence to RIAC. 401 Thelimits of work for Alternatives B2 and B4 were then overlaid on this plan to determine the additional area ofstate-regulated perimeter and riverbank wetland where construction would occur.The limits of state-regulated floodplains have been identified using a model presented in Section 5.14,Floodplains. Floodplain limits that extended beyond the limits of vegetated, perimeter, and riverbank wetlandswere identified by overlaying floodplain limits onto the plan prepared to identify work limits in perimeter andriverbank wetlands described in the previous paragraph.The state-regulated wetland impacts areas reported in this document only include areas impacted by airportenhancement activities under Alternatives B2 and B4. It does not include the impacts associated with thewetland mitigation developed to offset project-related losses to wetland functions and values. The RIDEMFreshwater Wetlands application for airport safety enhancements involving work within wetlands would alsoinclude calculations for wetland areas altered to conduct the required wetland mitigation activities. Thesestate-impact calculations are not included in the direct impact methodology as these activities are consideredmitigation by federal regulators.5.10.3.2 Indirect Impacts MethodologyIndirect impacts to wetlands may occur when wetland hydrology is altered as a result of new impervioussurfaces in a watershed, new or modified drainage patterns, or as a result of a direct wetland impact such asplacement of wetland fill. Other indirect effects could include impacts to the wetland wildlife habitat functionthrough fragmentation, alterations at the edges of resources, such as changes in species composition, and401 Letter from RIDEM to RIAC re: T.F. Green Airport dated September 24, 2004.Chapter 5 - Environmental Consequences 5-192 July 2011\\mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH05_Environmental_Cons_JUL_2011.doc