A rural Central Texas utility is combining groundwater expansion with the replacement of a more than 60-year-old transmission backbone as part of a roughly $45 million capital program aimed at improving water reliability for more than 12,000 residents.
The Bistone Municipal Water Supply District in Limestone County, approximately 37 miles northeast of Waco, selected New York City engineering firm STV in late February to design a $29.4 million water transmission and storage upgrade funded by the Texas Water Development Board’s (TWDB) State Drinking Water Revolving Fund.
The transmission upgrade will replace approximately 7.2 miles (about 40,000 linear feet) of 16-in. steel cylinder concrete pipe.
The work highlights a larger challenge facing rural water systems across Texas, where utilities are replacing mid-20th-century transmission lines and expanding groundwater supplies to meet today’s reliability and regulatory standards.
The transmission project follows a $16 million Texas State Water Implementation Fund grant approved in 2024 to drill up to 10 groundwater wells in the Carrizo-Wilcox Aquifer, one of Texas’ largest groundwater systems that stretches from the Louisiana border to south Texas.
Together, the projects form a phased capital program that expands groundwater supplies while modernizing the transmission and storage infrastructure needed to deliver that water throughout the district’s system.
“Yes, the two projects are closely linked,” said Scott Wetzel, senior project manager at STV. The well field expansion will increase the available groundwater supply, he said, but transmission improvements are needed to move that additional water through the district’s transmission backbone.
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“The updated main drive and pressure maintenance system is essential to take full advantage of the increased supply,” Wetzel said. “Without these improvements, the older infrastructure would limit the benefit of new wells.”
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Cross-sectional diagrams show the geologic layers of the Carrizo-Wilcox Aquifer, one of the largest groundwater systems in Texas that stretches from East Texas to the Mexican border. The formation supplies municipal, agricultural and industrial water to 66 counties.
Map courtesy of Texas Water Development Board
Engineers plan to replace the pipe with the same 16 inches. diameter to preserve system capacity while evaluating longer-lasting materials for the new main. According to Wetzel, the project team is considering molecularly oriented zinc-coated ductile iron and PVC tubing with a polyethylene coating to improve corrosion resistance and reduce the risk of breakage. HDPE pipe has also been evaluated for potential trenchless installation segments.
Most of the project funding will support pipeline replacement. Additional work includes construction of a 0.5 million gal elevated storage tank and installation of pressure stabilization infrastructure to maintain consistent service during peak demand and emergencies.
According to STV, the improvements are expected to stabilize system pressure in the 50 to 65 psi range, maintain compliance with minimum residual pressure standards and reduce leaks associated with the district’s aging transmission line.
The $29.4 million project represents the full capital cost and will be financed through TWDB, including a $19.4 million low-interest loan and $10 million in principal forgiveness.
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STV says it has worked with the district since 2022, when the company completed a preliminary engineering assessment and feasibility report that helped identify priority infrastructure improvements and secure state funding for construction.
The project follows a traditional design-bid-build delivery method, with a bid announcement expected in late 2027 and construction expected to begin in early 2028, according to STV. Planning, environmental review and fieldwork began earlier this year.
Wetzel said, depending on final design decisions, the transmission replacement and storage upgrades may be bid as a single construction contract or split into multiple packages.
For Texas’ smaller utilities, the Bistone program illustrates how state revolving fund and SWIFT funding is enabling rural districts to replace aging transmission systems while expanding groundwater supply capacity.
