The accidental release of 6,000 gallons of magnesium hydroxide into the Assabet River in May from Marlborough’s Westerly Wastewater Treatment Plant will cost the city $1,000 in administrative fees, in addition to the cost of repairs, according to the Massachusetts Department of Environmental Protection.
On May 7, workers accidentally allowed the chemical to overflow from a storage tank, resulting in elevated pH levels in the river several miles downstream from the plant, the DEP said.
The order mandates that Marlborough repair or replace the high-level alarm on the storage tank and to retrofit a spill containment system around the tank. The city must also develop a notification plan of local, state and federal agencies in the event of any future release.
