ROSWELL, GA — Fulton County's Big Creek Water Reclamation Facility has undergone a $350 million expansion, making it the most expensive capital project in the county's history. Built by The Walsh Group and located on Marietta Highway, this redevelopment is crucial for supporting growth in a 70-square-mile area in north Fulton County and parts of neighboring counties. The project involved significant upgrades, including a new pipeline from Cobb County and an expanded electrical substation. The facility now serves large portions of Johns Creek, Roswell, Alpharetta, and Milton, as well as having intergovernmental agreements with nearby counties like Cobb, DeKalb, and Forsyth for sewage treatment.

The expansion has increased the plant's capacity from 24 million to 32 million gallons of wastewater per day, using advanced flat-plate membrane treatment technology. This makes it the second-largest plant of its kind in the United States. The new technology allows the plant to process more water in less than half the previous space by using membranes that filter out most materials, followed by ultraviolet light treatment to eliminate remaining viruses. Additionally, the facility was designed to operate primarily through gravity, reducing the need for energy-consuming pumps. Notable improvements include repurposing large, previously sediment-settling tanks as emergency storage to prevent spills during heavy rain, with a capacity to hold up to 6 million gallons. These upgrades have improved the quality of water discharged into the Chattahoochee River, earning Fulton County recognition from the National Association of Counties. The cleaner outflow benefits Cobb County, located downstream, by lowering their water treatment costs. The Big Creek plant's upgrades, which started operations in 1972, have been strategically designed to accommodate future growth, with all new equipment built to last 50 years and handle potential expansions up to 38 million gallons per day.