Wastewater Treatment


The Authority operates and maintains 3 independent wastewater treatment plants in the Town of Edgefield (Brooks Street Plant), the Town of Johnston (Johnston Plant), and the Town of Trenton (Trenton Plant), along with gravity collection lines, force mains and 39 pump stations located in the Town of Edgefield, the Town of Trenton and portions of Edgefield County. The Authority also operates and maintains over 34 miles of sewer force mains and 3 lift stations that are part of the Regional Sewer System. This system conveys wastewater to the Horsecreek WWTF (not owned by ECWSA) for treatment.

The Authority’s Regional Sewer System comprises approximately 37,900 linear feet of 12 inch sewer force main from pump station #3 on Riegel Road in Johnston to pump station #2 on Star Road. From this pump station, a 16 inch force main runs parallel with U.S. Highway 25 for approximately 20,700 linear feet to the Pine House pump station in Trenton. From the Pine House pump station, approximately 63,500 linear feet of 18 inch sewer force main runs parallel with U.S. Highway 25, then reduces to a 12 inch sewer force main for approximately 8,800 linear feet and ties into North Augusta’s metering site on Austin Graybill. The force main continues under I-20 and along Ascauga Lake Road in North Augusta as part of the recently completed Mims Branch Project. North Augusta transports the wastewater flow from the Authority’s Regional Sewer System to Aiken County Public Service Authority’s (Aiken County PSA) system for treatment at the Horse Creek Wastewater Plant. The Authority has 2.3 MGD of capacity in this sewer main. The Authority acquired from North Augusta 1.3 MGD of treatment capacity at Aiken County PSA’s Horse Creek. The Horse Creek Wastewater Treatment Plant has a treatment capacity of 26 MGD and is currently treating approximately 13 MGD. Saluda County funded the cost of constructing a pump station at the Johnston Plant that interconnects a 16 inch sewer force main that runs from Saluda County to the Johnston Plant, then parallel with S.C. Highway 121 to the Pine House Pump Station in Trenton.

The Edgefield Plant (Brooks Street) was last upgraded in 2010 and currently has a treatment capacity of 725,000 gallons per day and treats an average flow of 198,000 gpd. The Edgefield Plant utilizes the sequencing batch reactor process, a form of activated sludge treatment, and the treated effluent from the plant is discharged to Beaverdam Creek.

The Johnston Plant uses a multi-cell aerated lagoon treatment process preceded by coarse solids and grit removal and followed by disinfection and flow monitoring. It provides secondary treatment of combined domestic and light commercial process wastewater. The plant has a design treatment capacity of 968,000 gpd and treats an average flow of 250,000 gpd. The treated effluent from this wastewater treatment plant is discharged into the South Fork Edisto River. The Johnston Plant is also connected to a Regional Sewer System pump station located on site as a backup. This connection enables the Authority to pump wastewater received at the Johnston Plant into the Regional Sewer System in lieu of treatment and discharge if operational problems are encountered at the plant.

The Trenton Plant uses as aerated lagoon treatment process. The plant has a design treatment capacity of 73,000 gpd. The plant normally has no discharge, due to wastewater being pumped into the Regional System.