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

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) EvaluationTable 6-12Alternative B4: Wetland Mitigation Estimated AcreageWetland Mitigation TypeCreation/Restoration (In Kind) 3Restoration/Enhancement (In Kind)Wetland/Buffer PreservationWetland MitigationSite Numbers1, 3, & 638 & 12CompensationSite Area(acres) 14.70.240.0USACENew England DistrictRecommended Ratio 22.04:1 43:115:1ImpactedWetland AreaEquivalent2.30.12.7Total 44.9 NA 5.1 51 The mitigation program will replace the functions and values of the impacted wetlands as required by USACE.2 Weighted average for all wetland classes impacted from New England District Compensatory Mitigation Guidance (7-20-2010) Table 1.3 PEM dominated by Phragmites will not be replaced in kind.4 The mitigation equivalent of a creation/restoration site is calculated by dividing the area of the site by 2.04 5 Alternative B4 would require mitigation for the loss of 5.0 acres of wetland.In addition to mitigating for impacts to vegetated wetlands, Site 2 involves the replacement of the BuckeyeBrook culvert at Lakeshore Drive that could enhance fish and wildlife passage and correct flooding problems onLakeshore Drive. If selected, the mitigation area equivalent of this activity would be negotiated with the USACEthrough an adjustment of ratios of impact to mitigation. The culvert replacement would substitute for otheractions listed in Table 6-11.6.10 Water QualityAlternative B4 would avoid water quality impacts by reducing roadway and parking areas within the TuscatucketBrook and Brush Neck Cove watersheds, thereby reducing pollutant loading. In addition, Alternative B4 wouldinclude improved water quality treatment for the relocation of existing roadways (Airport Road and MainAvenue). Alternative B4 would be designed to avoid disturbing Truk-Away Landfill soils. Total avoidance of thepotential to impact water quality would not be possible, as Alternative B4 would involve new impervioussurfaces, new parking, and increased aircraft operations. The design of Alternative B4 includes avoidance andminimization efforts to prevent any risks to water quality.Based on the impact analysis presented in Chapter 5, Environmental Consequences, there would be no significantimpacts on water quality, but there would be increases in impervious surfaces within some drainage areas forAlternative B4. Proposed mitigation measures developed in compliance with RIDEM standards would ensurethe receiving waters would not be impacted from new discharges. These standards would require on- andoff-site stormwater control measures to mitigate the impacts from the new impervious surfaces for AlternativeB4 and includes designing Alternative B4 in compliance with all applicable state and federal regulatorystandards, including the 2010 RIDEM Stormwater Design and Installation Standards Manual (SWDM), 491 to mitigatethe impacts to water quality and ensure the receiving waters are not impacted from new discharges.491 RIDEM and Coastal Resources Management Council, Rhode Island Stormwater Design and Installation Standards Manual, December 2010.Chapter 6 – Mitigation 6-32 July 2011\\Mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH06_Mitigation_JUL_2011.doc