Photo Courtesy of McCarthy

The Tarrant Regional Water District Richland Chambers Wetlands project, near Fort Worth, is now the second-largest constructed wetlands in the U.S. Completed in October 2013, the $43-million project exemplifies a trend in water treatment in which natural systems are used to assist in filtering and improving water quality.

In this case, water is diverted from the Trinity River, which is sometimes dominated by highly treated flows from a nearby wastewater treatment plant, into the Richland-Chambers Reservoir to provide additional raw-water supply. The 1,880-acre wetland system acts as a "living" filter that removes phosphorus, nitrogen and other nutrients.

The construction team built 34 miles of earthen levees to create five sedimentation basins and 20 wetland cells, 5 miles of interbasin canals, 54 concrete inflow-outflow and spillway control structures and 26 miles of aggregate levee roads. The team also installed 3.5 miles of large-diameter pipeline. The project required over 2 million cu yd of earthwork on a 2,200-acre site situated within a one-year floodplain.

The project was also one of the first civil projects in Texas to use construction manager at-risk delivery. McCarthy worked with the water district to develop a strategy to minimize schedule delays and the associated cost impacts of a major flood event. Ultimately, the team delivered the project on schedule and $5.4 million under budget.

Submitted by McCarthy Building Cos.

Owner Tarrant Regional Water District

Lead Design Firm Alan Plummer Associates Inc.

General Contractor McCarthy Building Cos.

Structural and Civil Engineers Alan Plummer Associates Inc.

MEP Engineeers CH2M Hill