On March 31, 2015, EPA filed a CAFO resolving CAA penalty claims against the City of Groton, Connecticut (Groton). Groton?s water purification facility violated the CAA by failing to comply with the RMP requirements of 40 C.F.R. Part 68. At the time of the matters addressed in the CAFO, Groton was storing up to 16,000 pounds of chlorine gas, an extremely hazardous substance, on the premises for waste treatment but failed to properly implement an RMP. Pursuant to the settlement, Groton will perform a SEP costing approximately $268,200 and pay a civil penalty of $7,000 to resolve liability for the violations. In order to complete the SEP, Groton will eliminate the use of chlorine gas at its facility and substitute liquid sodium hypochlorite, a much less toxic substance, in its stead. Due to Groton?s willingness to perform a SEP that will make the facility inherently safer and that costs much more than the penalty amount proposed under EPA?s Final Combined Enforcement Policy for Clean Air Act Sections 112(r)(1), 112(r)(7) and 40 C.F.R. Part 68, Region 1 sought and received a waiver from EPA Headquarters, allowing Groton to pay less than the 25% gravity amount required in EPA?s SEP Policy requirements.