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Title: Westchester County Streams, Byram River Basin, Flood Risk Management Feasibility Study, Fairfield County, Connecticut and Westchester County, New York : Final Integrated Feasibility Report & Environmental Impact Statement
Authors: United States. Army. Corps of Engineers. New York District.
Keywords: Byram River (N.Y. and Conn.)
Flood control
Environmental protection
Environmental management
Publisher: United States. Army. Corps of Engineers. New York District.
Abstract: The U.S. Army Corps of Engineers (USACE), New York District (District) has partnered with the Town of Greenwich, Connecticut to undertake the Westchester County Streams, Byram River Basin, Connecticut and New York (Byram River Basin) flood risk management feasibility study. This Final Integrated Feasibility Report and Environmental Impact Statement (FR/EIS) presents the results of the study team’s evaluation of various alternatives to manage the risk of damages caused by frequent fluvial, or riverine, flooding. This report fulfills the requirements of the National Environmental Policy Act of 1969 (NEPA) and was written in accordance with the President’s Council on Environmental Quality Rules and Regulations for Implementing NEPA (40 CFR §§ 1500-1508), the USACE’s Procedures for Implementing NEPA (Engineer Regulation 200-2-2), and other applicable federal and state environmental laws. Low lying neighborhoods in the study area have been subjected to repeated, severe flooding from high precipitation events, with the largest events being the storms of October 1955, June 1972, September 1975, and April 2007. A large number of structures are affected by flooding; the majority of structures impacted by the floods are single-family residential structures located in the Pemberwick neighborhood of the Town of Greenwich, CT. A factor contributing to the flooding issues in the basin are the West Putnam Avenue and Hillside Avenue bridges (U.S. Route 1 bridges) that carry U.S. Route 1 over the Byram River at the southern end of the study area. These bridges were built in the 19th and early 20th centuries and are currently owned and operated by the New York State Department of Transportation. Storm events deposit large amounts of precipitation in the Byram River Basin, all of which must pass beneath the U.S. Route 1 bridges. The U.S. Route 1 bridges have low roadway profiles and central piers. These features constrict the flow of the Byram River – acting as a bottleneck in the river – and cause the water surface elevation to increase upstream of the bridges and flood the Pemberwick neighborhood. Residents will continue to experience significant damages to their homes from fluvial flooding of the Byram River if no project is implemented. The Byram River Basin study’s purpose is to determine if there is a technically feasible, economically justified, and environmentally acceptable recommendation for federal participation in flood risk management for the Byram River Basin. The District considered a range of nonstructural and structural measures that have the potential to manage flood damages in the Town of Greenwich, CT, the basin’s most frequently flooded and densely populated locality. Through an iterative planning process, five flood risk management alternative plans were identified, evaluated, and compared. These plans were made up of measures that include levees, floodwalls, bridge removals and replacements, wet and dry floodproofing, structure elevations, acquisition of properties, and localized ringwalls. The Recommended Plan for flood risk management is the removal and replacement of the U.S. Route 1 bridges. The new bridges would not have central piers and would have roadway profiles with a higher elevation to allow more water to pass underneath them and decrease the risk of flooding. The Recommended Plan is estimated to provide $1,503,000 in annualized benefits under the USACE “intermediate” sea level change scenario (Price Level Fiscal Year 2020; Discount Rate 2.75%). The estimated benefit cost ratio of the plan is 1.3.
Description: Integrated Feasibility Report and Environmental Impact Statement
Rights: Approved for Public Release; Distribution is Unlimited
Size: 1105 pages / 121.57 MB
Types of Materials: PDF
Appears in Collections:Environmental Documents

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