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

T.F. Green Airport Improvement ProgramEnvironmental Impact Statement and Final Section 4(f) EvaluationMitigation Site 6The Spring Green Pond Inlet Stream originates in Wetland A2 as a ditch dug through the wetland (Figure 6-6).This ditch was apparently installed to lower the surface and groundwater elevation in the wetland. Whilerestoration of the original hydrology of wetland system could be achieved by backfilling the ditch and raisingthe culvert invert under Lydick Avenue, this action could result in unintended damage to properties abuttingthe wetland, including City-owned roads. This ditch is very steeply incised south of Lydick Avenue where itpasses through a former home site acquired by the Airport. A portion of the lawn area which abuts this channelwould be excavated to create approximately 0.4 acres of shrub and forested wetland next to the stream. Anupland buffer would be planted in the slopes grading to the wetland and existing mature trees would bepreserved. This would provide a floodplain function to attenuate flood flows and provide a wetland buffer toenhance the water quality of runoff. The site would be graded to drain back into the stream so a wildlife hazardis not created. Planting would consist of species that do not produce fruit sought after by wildlife such aswillow, alder, and sweet pepperbush. This area would provide a wildlife corridor for mammals travelingbetween habitats at Spring Green Pond and Wetland A2.The incorporation of wetland and buffer preservation at Mitigation Sites 8 and 12 may permit the project toachieve its wetland mitigation goals without Mitigation Site 6. This will be evaluated once agreements for thepreservation sites have been negotiated and mitigation credits have been assigned by the USACE.Mitigation Site 8The Three Ponds Brook wetland system south of the Airport Connector is located in the Pawtuxet Riverwatershed (Figure 6-7). The Three Ponds Wetland system is listed in City of Warwick Comprehensive Plan,Chapter 8, as one of the “priority open space sites for protection.” 488 This site offers an opportunity forpreservation of wildlife (primarily waterfowl and wading birds) and warm water fish habitats. Approximately2.1 acres of wetland impact would be offset by acquiring the development rights to 32 acres of dry oak forest,upland grassland, and a portion of the marsh. The preserved area would consist of approximately 12 acres ofmarsh. These acquisitions would protect the upland areas to the south and west of the marsh along with aportion of the wetland. Attempts to acquire development rights for 20 acres of surrounding uplands along thenortheastern part of the Marsh were abandoned after it was learned that a commercial office development hadalready been planned and designed for the area.Mitigation Site 12The Conimicut Point Marsh is named for its proximity to Conimicut Point in Warwick (Figure 6-8). It is theeasternmost part of the Mill River estuary (part of the Buckeye Brook Watershed) and is separate from the largermore prominent Mill Cove. The Mill River is formed below the confluences of Buckeye Brook with first WarnerBrook and then Lockwood Brook. The City of Warwick Comprehensive Plan Open Space Recreation Elementstates “The marshlands along Mill Cove support a large amount of aquatic life and are one of the City’s bestshelters for ducks”. 489488 www.warwickri.gov/index.php?option=com_content&view=article&id=852:city-warwick-comprehensive-plan&catid=67:planning-department&Itemid=159accessed January 24, 2011.489 www.warwickri.gov/index.php?option=com_content&view=article&id=852&Itemid=159 accessed January 24, 2011.Chapter 6 – Mitigation 6-30 July 2011\\Mawatr\ev\09228.00\reports\FEIS_Final_July_2011\PVD_CH06_Mitigation_JUL_2011.doc