Seneca, S.C., plant project improves aesthetics & efficiency
- Name: Seneca Water Treatment Plant
- Location: Seneca, S.C.
- Size: 20 mgd
- Infrastructure: particulate destabilization, coagulation, sedimentation, dissolved air floatation, filtration, chlorination
The city of Seneca, S.C., is located in the northwestern corner of the state (known as “the Upstate”), just across Lake Hartwell from Clemson University. Seneca is a steadily growing community of 8,352, according to the U.S. Census Bureau’s 2016 estimate, and its Seneca Water Treatment Plant recently completed an award-winning upgrade to better serve its increasing population.
Land of Lakes
Once a small manufacturing community, Seneca began to expand in the mid-20th century due to the creation of nearby man-made lakes Hartwell, Keowee and Jocassee. The new lakes provide consistent sources of clean water to nearby communities and offer numerous recreational opportunities, but their construction permanently altered the area around Seneca. Among other things, the city had to relocate its water treatment facility, which was in an area that was soon to become part of Lake Keowee. In 1968, it opened the Seneca Water Treatment Plant on the shore of Lake Keowee (from which it draws its water supply), and since then, the facility has provided high-quality drinking water to residents of Seneca and its surrounding areas.
Initially, the plant had a capacity of 4 million gal per day (mgd). After expansions in 1981, 1990, 2005 and 2009, its treatment capacity now stands at 20 mgd. It includes three treatment trains, with two basins and two filters per train. Two of the trains provide conventional treatment—particulate destabilization followed by coagulation, sedimentation, filtration and chlorination; the third uses dissolved air flotation (DAF) to remove particulates prior to filtration.
“We were one of the first, if not the first in the U.S., to convert from a traditional sedimentation basin to a DAF basin,” said Robert Faires, director of utilities for Seneca Light & Water. “Our water source is so pristine [that] it was and is difficult to treat with traditional sedimentation, hence the DAF conversion.”
Seneca Water Treatment Plant's upgrade added to its aesthetic appeal.
A Model Upgrade
From 2014 to 2016, the Seneca Water Treatment Plant underwent an $8.9-million upgrade that addressed issues, both inside and outside the facility.
In the decades following the plant’s construction, a residential neighborhood—Normandy Shores—grew around the facility. The plant’s aesthetics, which initially were not a significant concern due to its somewhat remote location, began to stick out in an area that grew to feature a number of luxurious, expensive waterfront homes.
To address residents’ concerns, Seneca city officials opened a dialogue with the neighborhood homeowners’ association. Among other concerns, the residents cited the plant’s intake structure, which consisted of several large, loud pumps on the otherwise tranquil shore of Lake Keowee. The new intake structure resembles a lighthouse, which blends with the community’s aesthetic and helps to reduce the noise produced by the pumps. The facility’s exterior also was updated, a public meeting space was added and the grounds were beautified using locally sourced materials wherever possible.
The facility also altered its chlorination procedure. Prior to the upgrade, the plant used a toxic gaseous chlorine in its treatment process. This presented a danger to plant employees, so the utility changed the facility’s disinfection method to a liquid sodium hypochlorite that is produced on site. This generation process uses pure salt as a base, so it is much safer to transport and use, and because the disinfectant is produced at the facility, neighborhood traffic is reduced.
Finally, the plant’s sludge handling process was updated. Its antiquated sludge clarifier was removed, and a screw press replaced its sludge press. This has helped the facility achieve far greater energy efficiency than before—its administrators estimate that it now uses 30% less energy than is typical in the industry.
The Seneca Water Treatment Plant’s upgrade has been well received by both residents and external agencies. In 2016, the Municipal Assn. of South Carolina presented the city of Seneca with its Municipal Achievement Award; the program is designed “to recognize and encourage innovations and excellence in local government.” Additionally, the plant received an Envision Silver award from the Institute for Sustainable Infrastructure in 2017 in recognition of its increased efficiency and sustainability. It is the third plant in South Carolina to receive an Envision award, and the first in the state to receive a Silver award.
“It’s an honor to receive this recognition for all the hard work and dedication in providing an efficient, environmentally safe and sustainable water treatment process,” Faires said.
New treatment procedures help improve worker safety