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

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) Evaluation5.14.3.3 Cumulative Impacts MethodologyCumulative impacts to other natural and beneficial floodplain values were assessed based on the history ofAirport construction and expansion activities as well as a review of historical aerial photographs. A 1939 aerialphotograph that depicts the Airport prior to any of the major runway construction activities has been used as abaseline for qualitatively assessing cumulative impacts. For the cumulative impact analysis, this 1939 aerialphotograph was compared to a 2004 aerial photograph. For purposes of assessing the cumulative impacts, it hasbeen assumed that the wetland area interpreted from the 1939 aerial represents the maximum extent of thebaseline 100-year floodplain. A 1951 aerial photograph depicts the beginning of landfill operations (not airportrelated)that eventually displaced the floodplain associated with the reach of Buckeye Brook adjacent to theRunway 34 End. Consideration also was given to anticipated planned projects as documented in Table 5-5.5.14.4 Impact AssessmentThis section provides a summary of the evaluation of impacts to the estimated floodplain for Buckeye Brook forAlternatives B2 and B4 and compares them to the No-Action Alternative.5.14.4.1 No-Action AlternativeThe No-Action Alternative would not require work within the 100-year floodplain and therefore, would notresult in any new impacts to floodplains.5.14.4.2 Alternative B2Activities associated with Alternative B2 that have the potential to impact the floodplain include safety projects(improving Runway 34 RSA and relocating Taxiway C) and efficiency projects (extending Runway 5-23 to thenorth with the associated relocation of the AMF access road). Fully Relocated Airport Road is located outside ofthe floodplain depicted on the FIRM and would not impact this floodplain.Direct ImpactsAlternative B2 would both affect the floodplain’s ability to provide some natural and beneficial values(specifically flood storage, water quality maintenance, and groundwater recharge) within the wetland setting ofmost of the floodplain. Impacts to existing wetland functions and values are considered in Section 5.10, Wetlandsand Waterways. Table 5-126 presents a summary of these impacts calculated based on FEMA mapping for thepurposes of federal permitting. Impacts to floodplains are also shown in Figure 5-46. Impacts due tonavigational aids are considered negligible because the volume of each navigational aid between the existingground elevation and elevation 14 feet above NAVD 1988 is anticipated to be less than one cubic yard andwould be negligible compared to other proposed actions.Chapter 5 - Environmental Consequences 5-246 July 2011\\mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH05_Environmental_Cons_JUL_2011.doc