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Combined Sewer Overflow Program

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From Water Environment & Technology, October 2000

Every year, the U.S. Environmental Protection Agency (EPA) and the Water Environment Federation (Alexandria, Va.) recognize outstanding achievements of wastewater treatment facilities through facility operations and maintenance, programs, and projects in the United States.

Nominated by regulatory agencies to compete for regional EPA awards,these facilities, programs and projects are evaluated by specially appointed selection panels for national awards. Featured in the following pages are the year's national winners. The winners met numerous rigorous criteria set by EPA Headquarters, but we highlight only their most effective or innovative features. The winners will be recognized at an awards ceremony on Monday, October 16, from 11:30 am to 1 pm at WEFTEC 2000 in Anaheim, Calif.

Saco, Maine's CSO Master Plan involves eight CSO construction projects and best management practices (BMP), including infiltration and inflow reduction, flow slipping, sewer separation, construction of a 75-ft (23-m) clarifier, and conversion of two existing 50-ft (15-m) clarifiers to CSO primary treatment facilities. The plan is expected to be completed by October 2010.

To date, the city has separated approximately 35% of its combined collection system, constructed in-line storage facilities, converted an abandoned tank at a pump station for off-line storage, and increased one pump station's pumping capacity. As part of its ongoing BMP program, the city also has installed a number of underflow buffers at its CSO regulators to control discharge of floatable materials.

These efforts have eliminated two of Saco's nine CSO regulators, significantly reduced the number of CSOs from the remaining seven structures, and reduced related street and pavement flooding. They also have enabled long-closed shellfish beds in the lower Saco River to be reopened to conditional harvesting.