DEP accepts proposed water treatment proposal

Water Department awaits consent order to treat high manganese levels

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GROTON — The treatment of manganese levels in town recently received major support from the Massachusetts Department of Environmental Protection.

Thomas Orcutt, Groton’s water superintendent, met with members of the DEP last week and confirmed that the department accepted a letter containing a proposed treatment method for reported high levels of manganese in two town water wells.The letter, submitted on Aug. 15, was prepared by Comprehensive Environmental Incorporated out of Bolton on behalf of the Groton Water Department.

Between January 2018 to July 2019, the town collected samples of the water at two wells located near Whitney Pond. Both wells were found to have levels of manganese over .30 mg/L at least five times, despite the DEP’s health advisory that recommends people not drink water with manganese levels over .30 mg/L.

Orcutt said that all that remains is for the DEP to provide a consent order to the Groton Water Department for its proposal. Orcutt said the specific date the department will start implementing the proposal is “TBD,” with the Groton Water Commission discussing an implementation schedule at a future meeting.

According to the letter, the Water Commission voted on Jul. 23 to treat the water out of the two Whitney Pond wells at the Baddacook Pond Water Filtration Plant using Greensand Plus media filtration. The method would involve the town Water Department funding the construction of a raw water transmission main to the Baddacook plant and an expansion of the plant.

That work would involve installing about 6,800 feet of eight-inch raw water distribution main and 4,100 feet of 12-inch finished water distribution main. The work would also involve converting 5,500 feet of 12-inch water distribution main into finished water distribution main along with 1,600 feet of eight-inch water distribution main into raw water distribution main.

According to a map provided in the proposal, the two water mains would run from the Whitney Pond wells  westbound along Lowell Road to Baddacook Pond Road.

The proposal also details the expansion of the Baddacook plant, which would have two horizontal Greensand Plus media filters to better remove manganese from the public water. Baddacook would also have two bulk storage areas, one for potassium hydroxide and one for sodium hypochlorite, along with a combined chemical feed area with day tanks for both chemicals. The expansion would also add a finish water metering pit and a new control panel able to monitor all four Greensand Plus filters.

At the plant, the raw water from both the Whitney Pond and Baddacook Pond would be chemically treated through the new day tanks in the chemical feed area and metering pumps. The water will be routed to a common header across the four Greensand Plus filters, which the letter says will allow for “operational flexibility.”

The proposal’s Corrective Active Schedule expects the renovations to be completed by late 2024.