West Area Combined Sewer Overflow Facility

Atlantic Skanska was awarded a $47 million contract from the city of Atlanta to construct the new West Area CSO Treatment Plant. The new facility is part of the City's plan to bring the combined sewer system into compliance with federal and state water quality laws. CSO's are a primary source of water pollution in major metropolitan areas. Once constructed, this facility will reduce CSO discharge into waterways, reduce bacteria and provide control over pollutants.

The scope of work on this project includes construction of a drum screen building, vortex solids complex, detritus separators, an electrical building and sedimentation basins where water is collected and stored. Other construction work includes a chemical building; a new system to filter the water, a blower building and a dechlorination chamber. The process equipment package is over $10 million. Work also includes construction of an operations building and junction/diversion structures. The contract includes installation of 13,000 lf of associated piping, a $3.3 million electrical package, $2.8 million instrumentation package and over $2 million of architectural work. Installation of 20,000 cubic yards of concrete is also included in the contract as is site grading, paving, and landscaping. Because there are three other contractors also performing work on this site, close coordination with the City of Atlanta is a necessity.

When completed, the new CSO plant will have a treatment capacity of 85 MGD. The combined sewage stored in the tunnel system will undergo both physical and chemical treatment prior to discharge into receiving waters. The treatment processes will utilize clarification and filtration to remove suspended solids and disinfection with chlorine. Prior to being discharged into the nearby Chattahoochee River, the wastewater will be dechlorinated with sodium hypochlorite and sodium bisulfite.