To minimize the effects of combined sewer overflows (CSOs) on local waterways, Bucksport, Maine, has installed equipment that captures and treats stormwater and wastewater before it discharges at an outfall point. In addition to improving local water conditions, the project has created a new community amenity at a previously unused waterside site.

Because the town's main pump station could transport only 1 million gallons per day to the treatment plant, surging flows from storms would back up and flow to the Penobscot River. Facing a federal mandate to clean up CSO discharges, Bucksport officials considered several options, including adding capacity to the wastewater treatment plant to reduce overflows and constructing a separate collection system for stormwater and wastewater. Ultimately, they chose a third option: treating stormwater before it discharges into local waterways with a 2.9-million-gallon-per-day hydrodynamic vortex separator, called the Storm King, manufactured by Portland, Maine-based Hydro International.

The new design diverts high flows to a dedicated pump station, which conveys the water to the new treatment unit where solids are separated and the water is treated with chlorine to reduce fecal coliforms. From there, treated water flows through the outfall, and the collected solids are gravity fed to the sewage treatment plant.

Bucksport used the project as an opportunity to improve several neglected buildings located next to the outfall. The town demolished the existing buildings and built the new pump station, fishing pier, fountain, water wheel and pond. In front of the site stretches a mile-long waterfront walkway and picnic tables with views of Penobscot Bay, the Penobscot Narrows Bridge and the 19th century Fort Knox on the other side of the Penobscot River. “We built a building that people think is a restaurant or museum,” says Town Manager Roger Raymond. “No one would think that it's a CSO treatment facility.”

The $3.1 million project was paid for with several rural development, community development, public infrastructure and enterprise grants. Since the separator was installed, the city has met all regulatory requirements during heavy rains.

Project: Combined sewer overflow treatment
Jurisdiction: Bucksport, Maine
Agencies involved: Public Works Department, Mayor's Office
Vendor: Portland, Maine-based Hydro International Inc.
Date completed: August 2009
Cost: $3.1 million