East Fork Water Reuse Project

As the largest project in Texas using reclaimed water to augment a surface water supply source, the East Fork Water Reuse Project provides the North Texas Municipal Water District (NTMWD) with over 102,000 acre-feet of water per year, which is enough water to serve 500,000 people. Completed at a cost of less than 25% of developing a new reservoir, in about 20% of the time, the East Fork Water Reuse Project is a signature solution of innovation.  

Plummer developed the reuse strategy alongside NTMWD. The project consists of diverting an average of 91 million gallons per day (mgd) of effluent-dominated water from the East Fork of the Trinity River and polishing the water in one of the largest constructed wetlands in the country (2,000 acres). The wetland-treated water is then pumped 43.5 miles to Lavon Lake to augment the District’s surface water supply source. East Fork Water Reuse Project includes six major components:  

• 165 mgd peak capacity diversion pump station to pump water from the East Fork Trinity River
• 2,000 acre constructed wetland to provide polishing treatment of the diverted East Fork water
• 150 mgd peak capacity conveyance pump station to pump the polished water to Lavon Lake
• Electrical substation to provide power for the conveyance pump station
• 43.5 miles of 84-inch diameter conveyance pipeline starting near Crandall, Texas and extending through Kaufman, Rockwall, and Collin counties to transfer water from the wetlands to Lavon Lake
• John Bunker Sands Wetland Center, which provides public access and educational programs

As the prime consultant for the design effort, Plummer designed the treatment wetland, the conveyance pump station, and approximately 31.5 miles of the 84-inch pipeline and managed the work of a sub-consultant for design of the remaining 11.5 miles of pipeline. Plummer performed significant environmental and permitting work for the wetland site and the pipeline route, working successfully with local, state, and federal regulators to obtain the necessary water rights and environmental permits.

The pipeline route runs through Kaufman, Rockwall, and Collin Counties. It was a significant challenge to determine a route that minimized pipe length and static head for the conveyance pump station. Several routes were studied with the use of aerial photography, parcel maps, and digital elevation model (DEM) topographic information to select the preferred pipeline alignment.

The pipeline is divided into three segments: Northern, Central, and Southern. The design of the Lake Lavon outfall structure, the terminus of the northern pipeline segment, included the challenge of meeting budget and maintenance requirements of the NTMWD and permitting requirements of the U.S. Army Corps of Engineers. In addition, the final route included several stream, railroad, highway, and utility crossings.

The conveyance pump station was designed for an ultimate peak capacity of 150 mgd at 550 total dynamic head (TDH), or 240 psi. The interim capacity is 110 mgd at 380 TDH (165psi). Three 3,000-hp vertical turbine pumps were selected to provide the initial pumping capacity. These pumps were preferred because the motor was required to be located above floodplain, and the flow-head characteristics satisfied the pumping conditions. Two of the pumps are equipped with variable frequency drives (VFDs) to allow the pumps to match the varying flow coming from the wetlands. Two additional pump cans were provided to house two 6,000-hp pumps. These will be installed to meet peak demand in the future.

The pump station is equipped with a SCADA system to allow NTMWD to operate the station from its main operation base about 30 miles away. A separate electrical substation was constructed solely to provide for the large power demand of the pump station.

Major hurdles and innovations for the design of the conveyance pump station included:

• Expansive Clay – Due to the large amount of expansive clays, Plummer developed an innovative, cost-saving structural design employing deeper piers to allow joints to be more flexible, as well as pipe-in-pipe design to allow movement.
• Floodplain – Plummer had to determine the floodplain to use for pump elevations to keep motors and electrical gear outside of the floodplain. To accommodate the design, Plummer built up the structure using the soils recovered from the site.
• Flow – Determining flow was a challenge due to the Lake Tawakoni flow split. The present pump capacity versus future capacities had to be determined and pumps had to be selected for present energy efficiencies as well as future pumping abilities.

Plummer provided full-time resident representation on the site throughout construction of the wetland, pump stations and pipeline segments. East Fork Water Reuse Project exemplifies the value of public and private entities working together to provide multiple benefits to the community. Through its partnership with the Carolyn Hunt Trust Estate and construction of the John Bunker Sands Wetland Center, the project not only provides water supply, but also offers opportunities for research, education, wildlife observation, and community gatherings. As a result, the project has been visited and embraced by the public, regulators, and legislators locally, nationally, and internationally.

Plummer is proud to be associated with this project, which received the following awards:

• 2013 North Central Texas Council of Governments Celebrating Leadership in Development Excellence (CLIDE) Award
• 2012 American Council of Engineering Companies National Honor Award
• 2012 American Council of Engineering Companies Texas Section Engineering Excellence Gold Medal
• 2012 National Association of Environmental Professionals Environmental Stewardship Award
• 2011 TCEQ Texas Environmental Excellence Award
• 2008 WateReuse Association Large Project of the Year