Combining Flood Mitigation and River Restoration Opportunities to Achieve Public Benefits and Ecologically Sustainable Solutions in Peabody, Massachusetts

The City of Peabody has experienced recurring flooding problems since the 1950s. Five major flood events have occurred in Peabody since 1996; three of these were declared Federal Disasters. These events have resulted in major flooding in the Peabody Square area, which is located in the heart of the city's downtown. The North River is the main drainage conduit in Peabody, which flows from Peabody Square approximately 1.5 miles downstream to the ocean at Salem Harbor. The watershed for North River encompasses nearly 11.5 square miles. Approximately 9.2 square miles, or 80 percent of the tributary watershed area, is conveyed to the North River through two culverts that converge into a main culvert at a subterranean intersection in the downtown area at Peabody Square. In 2008, the City and AECOM prepared a Preliminary Design Report (PDR) for flood mitigation facilities for the Peabody Square area. The recommended alternative was intended to eliminate flooding in Peabody Square for events up to a 50-year storm, while not causing any adverse impacts downstream in the neighboring community of Salem, Massachusetts. The PDR recommended alternative involved installation of subterranean culverts to convey flood flows below Peabody Square and discharge these flows downstream into the North River, as well as widening the North River downstream of Peabody Square to its mouth at Beverly Harbor in Salem.Since preparation of the PDR, the City has recognized that the need to modify the North River's dimensions, morphology, and hydrology presents an opportunity to achieve habitat improvements and improve natural river functions. The City is now assessing alternatives that have a stronger incorporation of stormwater management through use of Low Impact Development (LID) and Best Management Practices (BMPs), as well as river and stream restoration components. Watershed modeling is currently underway to assess flood flows and maximize upstream storage, thus retaining flows in contributing sub-basins and minimizing downstream flooding. The proposed widening of the North River also provides opportunities to address potential contamination issues at parcels along the North River, and provides opportunities for revitalization of currently degraded parcels that are not economically viable. In addition, the proposed downtown projects will facilitate development of a planned Downtown Riverwalk and green space along the length of the North River. The City of Peabody is using creative solutions to address historic flooding problems by integrating flood control with sustainable approaches to changing watershed and river characteristics. This paper presents solutions that have been implemented as well as the City's vision for the future.