Union County Aquifer Restoration

Union County Aquifer Restoration

Location: El Dorado, Ark.

Client: Union County Water Conservation Board

Completion Date: 2003

South central Arkansas obtains its raw water supply from the Sparta Aquifer. Over the past 50 years, the Sparta has been declining with the greatest depression in the water table centered under the City of El Dorado, in Union County, Ark. The Union County Water Conservation Board was organized to evaluate options to save the aquifer. Burns & McDonnell was hired by the board to develop a master plan to evaluate alternatives to relieve the demands on the Sparta Aquifer. At the same time, a merchant power plant was being developed in the county and needed an estimated 20 million gallons per day for cooling. The master plan recommended supplying raw water from the Ouachita River to the fledging power plant and large local industries, thereby eliminating the need for these facilities to use groundwater.

The Ouachita River supports barge traffic and is a controlled release waterway by means of a Corps of Engineers Lock and Dam upstream of El Dorado. Burns & McDonnell conducted a field survey and sounded the river above the lock and dam to locate the most suitable site for a river intake where the lock and dam would sustain the water level. Two sites were located that were 20 feet deep at the shore, one near Calion and one near Champagnolle Point. The site at Calion was selected because it was easily accessible from local roadways and was close to a suitable electrical supply.

A 30 percent preliminary design of a 65-MGD side-stream river intake and pump station was completed and turned over to Panda Energy, the power utility developing the new power plant. The facility included a self-cleaning bar screen and two traveling water screens with provisions to be converted to a fish-friendly system, should the need arise. A two-cell wet well, each cell with two vertical turbine pumps, was provided for ease of maintenance and repair without shutting down the facility. Each pump is 400 hp and designed to produce 15,050 gallons per minute, for a firm capacity of 65 MGD. Access to the intake is on a 1,300-foot-long access bridge with service deck at the river. The access bridge is needed because the intake typically floods annually.

Panda shared the cost of the intake facilities with the board and handled final construction through a modified design-build approach.

  • 65-MGD river intake
  • Mechanically cleaned bar screen
  • Two traveling water screens
  • Quarter-mile-long access bridge with service deck
  • Four 15,050 gpm vertical turbine intake pumps
  • 48-inch raw water transmission line
  • Regulatory agencies coordination