The Acton Select Board voted unanimously to approve construction of a wastewater equalization tank at the Adams Street wastewater treatment plant to serve the Powder Mill sewer extension and the new Powder Mill Place development.

Engineer Jack (Woodard & Curran) described the proposal as a roughly 300,000-gallon above-ground storage tank sized to meet Department of Environmental Protection (DEP) conditional permit requirements and to provide operational buffer for peak wet-weather flows. The tank would sit at the treatment plant site and be used intermittently to hold high flows, then pump that stored flow back to the plant when downstream flows recede.

Town staff estimated the project’s current funding gap at roughly $2,600,000. The project includes a developer contribution of $1,000,000 toward the tank; staff said the town will pursue grant funding — including MBTA-community funding programs for eligible projects — and, if necessary, a borrowing authorization to be repaid through the sewer enterprise fund.

Select Board Member David moved approval of the plan. The motion carried unanimously.

Jack described operational benefits beyond permit compliance: the tank provides capacity for maintenance and repairs by allowing operators to buffer flows while a reactor or treatment train is taken offline. He also said the tank’s covered design will include aeration and odor controls. "It pumps into the tank, and then we would bleed it back in once the flows recede," Jack said.

Staff said they will pursue grants and bring a borrowing article to town meeting if grant awards do not fully cover the town’s share. Construction and final design work will continue; town officials said additional II (inflow & infiltration) investigation and targeted repairs remain a parallel priority to reduce long-term average flows into the plant.

Next steps: staff will continue design, file grant applications, and return to the board with final funding and borrowing language for town meeting approval if needed.