Revised Flood Maps Cause Warwick to Reconsider the Safety of its Treatment Plant

Warwick, Rhode Island's Advanced Wastewater Treatment Facility is located in a natural depression without an outlet and surrounded on three sides by a flood control levee designed in the early 1980s to protect the site to what was then the 100-year flood level. Between March 27, 2010 and March 31, 2010 the City received 22.35 cm (8.8 inches) of rain. The river crested 0.91 m (3 feet) above the top of the dike, flooding the plant with over 3 m (10 feet) of water in a matter of hours. Beginning first with primary treatment and drip disinfection and followed by secondary treatment, the plant saw treatment slowly restored over the course of several weeks. Full recovery of permanent power and control systems took nearly a year due to the lead time associated with the switchgear, motor control centers, and emergency generator. During reconstruction, older equipment was replaced with more energy-efficient equipment using Department of Energy grants and utility rebates. After the flood, the United Stated Geological Survey began the process of updating the area's flood maps to take into account higher river flows and more frequent flooding. As a result, flood mitigation measures being considered include raising the levee surrounding the facility to at least the 500-year flood level, addressing drainage from nearby Interstate 95, and controlling seepage under the levee. This paper examines the emergency response and recovery from the flood, including equipment replacement, electrical system repair, and energy upgrades. Importantly, it then also details the steps taken to mitigate a similar event in the future.