Setting a new standard for flue gas desulfurization (FGD) wastewater management

Santee Cooper Winyah Generating Station FGD Wastewater Treatment Plant

Due to rising power demand in 2023, Santee Cooper needed to be able to operate Winyah Generating Station (WGS) past the 2028 alternative compliance date based on cessation of coal-fired power generation. Located near Georgetown, South Carolina, WGS has four coal-fired units that generate 1,260 megawatts and uses wet flue gas desulfurization (FGD) scrubbers to remove sulfur oxides. Extending the life of WGS to meet the region’s growing power needs required the addition of a wastewater treatment system that would meet current U.S. Environmental Protection Agency (EPA) regulations. Santee Cooper reached out to our team to help.

We delivered a full suite of services, from detailed engineering and design to permitting support, vendor management, construction oversight, and commissioning. Our goal was to provide Santee Cooper with a reliable system at WGS that met EPA effluent guidelines while supporting safe, efficient power generation.

Drawing on our experience with FGD wastewater, we developed an interactive mass balance to track key constituents the coal pile to scrubber effluent. This allowed WGS operators and our team to predict changes in blowdown chemistry with different coal blends or operating conditions and define a design basis covering all operating ranges. We conducted an alternative analysis to evaluate technologies beyond best available technology (BAT), including spray dryer evaporators, and performed bench testing to optimize chemical dosing and address uncommon selenium species.

The resulting two-story, 200,000-square-foot (18,581-square-metre) wastewater treatment plant houses ultrafiltration, chemical storage and dosing, filter presses, electrical and control rooms, and office space. This facility will help improve the quality of water discharged from the power generating stations, enhancing the surrounding ecosystems. Santee Cooper can continue operating within their environmental permits, supplying ongoing compliant and reliable power generation for the communities they serve for years to come.