FAIRFAX, VA. — A new permanent water intake system at the Duke Energy Belews Creek Steam Station in Stokes County, N.C., designed by Dewberry, has resolved challenges with low water levels in Belews Lake while protecting fish and other ecosystems within this tributary of the Dan River. The Belews Creek Steam Station is Duke Energy’s largest coal-burning plant in the Carolinas.
Increased withdrawals from Belews Lake, necessitated in part by new scrubbers installed to meet more stringent air pollution control requirements, had resulted in critically low lake levels that threatened power production at the 2.24-GW, two-unit coal-fired generating plant. Duke Energy sought a permanent solution to the challenge in place of costly emergency temporary pumping measures that were used to transfer water from the Dan River to Belews Lake.
Dewberry designed a permanent 65 million gallons per day (mgd) (100 cfs) raw water intake system, consisting of two velocity caps, fish screening, and four 16-mgd (25 cfs) vertical turbine pumps. The system is currently operating at a targeted transfer rate of up to 26 mgd (40 cfs) with only two pumps. The project also included installation and routing of transmission piping to Belews Lake, consisting of six, 18-inch-high-density polyethylene (HDPE) transmission mains and a discharge energy diffuser manifold system installed within the lake.
The large volume of water withdrawal and the shallow depth of the Dan River precluded conventional river intake solutions. The use of the velocity caps is the first of its kind in North Carolina, with only a few installations in the United States. The fish screen was selected to comply with the new (March 2011) Environmental Protection Agency (EPA) draft regulation, “Power Plant Cooling Water and Clean Water Act 316(b),” which specifies a new environmental standard for the protection of ecosystems impacted by the power industry.
The project involved extensive hydraulic modeling to size the pumping facility and ensure adequate volumes of water could be transferred to Belews Lake during historic drought periods. Dewberry and Duke Energy joined efforts in obtaining multiple permits from numerous regulatory agencies, performing public outreach and addressing concerns of environmental groups.
“This was a major water transmission project that resolved Duke Energy’s water intake challenges while protecting these waterways,” said Scott Ehrhardt, P.E., project manager in Dewberry’s Danville, Va., office. “The Dan River is a pristine river that contains threatened and endangered species and is widely used for recreation. Proper design of the withdrawal structures and development of variable withdrawal schemes were key to minimizing impact to the ecosystems and recreational uses.”