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

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) Evaluation5.11.5 Short-term Impacts from Temporary Construction ActivitiesIn the absence of mitigation, the construction phases for Alternatives B2 and B4 could result in short-term,temporary impacts that would end when construction is complete. As the construction would take severalyears, these impacts would vary as different phases of the Improvement Program were completed. A RIPDESpermit for construction activities would specify measures that the Airport would be required to implement toprevent construction-related stormwater impacts.Although Alternative B2 and B4 are different, their construction-related impacts would be similar, if notidentical. Therefore, the construction impacts are grouped by type rather than by Alternative B2 or B4. Waterquality impacts due to construction could be caused by four primary types of activities: erosion and dischargeof sediment from earthwork; spills of hazardous materials; channel relocation; and dewatering.5.11.5.1 Erosion and Discharge of Sediment from EarthworkThe construction of RSAs, taxiways, runways, roads, and buildings would expose unvegetated soil that coulderode and be deposited in the Airport’s waterways and receiving waters, if appropriate mitigation measureswere not taken.5.11.5.2 Fuel SpillsConstruction using heavy equipment involves hydraulic fluids and would require storing and transporting fuelon site. An accidental release of hydraulic fluid, or fuel during refueling could have the potential to contaminatesoil, groundwater, and surface water. Spill containment procedures, including limiting the areas in whichfueling could be performed, would be implemented to minimize this risk.5.11.5.3 Channel RelocationAlternatives B2 and B4 would require relocating waterway channels. Newly constructed channels could contributesediment into the stream during an initial establishment period, which could lead to a temporary increase inturbidity downstream. Erosion control would be necessary during construction to contain sediment andcontaminants to prevent turbidity downstream and short term impacts.5.11.5.4 DewateringAlternatives B2 and B4 may require dewatering of excavations during construction activities to keep excavated areasfree of groundwater (fill and construction near the Runway 34 End, the relocation of existing Airport Road, and therelocation of stream channels). Under Alternative B4, the realignment of Main Avenue could also require dewatering.Untreated dewatering fluids typically contain silt and suspended sediments, which could be harmful to surfacewaters if discharged directly. Dewatering could also expose pollutants from contaminated groundwater, particularlynear contaminated sites such as the former Truk-Away Landfill near the Runway 34 End; all dewatering will be inaccordance with RIDEM requirements. Although the groundwater at the former Truk-Away Landfill has beenshown to meet Rhode Island groundwater quality objectives, the remaining light non-aqueous phase liquid (LNAPL)and contaminated soil at the site may contribute pollutants to dewatering discharges nearby. Both alternatives wouldbe designed to avoid disturbing Truk-Away Landfill soils. No dewatering will occur unless a RIPDES permit isobtained. These effects would be minimized using appropriate mitigation measures, as described in Chapter 6,Mitigation.Chapter 5 - Environmental Consequences 5-220 July 2011\\mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH05_Environmental_Cons_JUL_2011.doc