In the summer of 1994, USEPA responded to an oil release into the Housatonic River emanating from an operating hydroelectric facility, located at140 Roosevelt Drive, the former Hull Dye facility, in Derby, Connecticut. This facility housed two electricity producing turbines which, when operating, were powered by water from an up-gradient canal which is fed by the Housatonic River. Oil saturated soil and river sediment adjacent to the facility were excavated and an interceptor trench and recovery well system were installed close to the breakout location. In 1999, another oil sheen appeared which was emanating from the facility tailrace. After shutting down the turbines and a thorough investigation, a second oil recovery system was installed over the suspect source area in August 2000 and was operated up until 2013.
Due to a continuing seepage of subsurface oil into the facility tailrace, a sandbag and riprap dam that physically separates the tailrace from the Housatonic River was constructed in 2007.
After years of study and remediation, EPA determined in 2017 that sealing the walls and floor as planned was not feasible and major reconstruction would be necessary to bring the hydroelectric facility back on-line.
After discussing the situation with National Pollution Funds Center (NPFC) Case Officer, it was determined that EPA would evaluate two options. The first was to bring the plant back on-line as a viable hydroelectric plant and the second was to effectively shut down the facility. The deciding factors would be the ultimate cost and the probability of preventing future discharges of oil to the river.
In March 2018, EPA began working with their contractor to evaluate the two options. The interim report concluded that bringing the plant back on-line with extensive renovation would be more expensive than shutting down the facility and would take longer to implement. The NPFC and EPA agreed that attempting to bring the plant back on-line would be cost prohibitive. In addition, EPA proposed including an oil recovery system into the permanent closure design, so the potential for a future oil breakout to the river would be diminished.
In 2019, EPA’s contractor was tasked with preparing a 100% design/cost report for sealing the tailrace and permanent closure of the hydro-plant, building on the interim report. The final design/cost report was completed in early 2020.
Due to funding limitations, only minor preparatory activities were conducted in 2020. The work to effectively seal the tailrace and prevent future outbreaks of oil to the river is expected to commence in the spring of 2021.