Weslaco, TX Water Treatment Plant Construction Management-At-Risk CDM SMITH


Weslaco, Texas is a small border town in the Rio Grande Valley in the middle of the country’s most arid and economically diverse, yet fastest-growing county, Hidalgo County. These circumstances in combination with the areas population pressures, meant the city’s existing water plant would be unable to meet anticipated demand.

The Weslaco water treatment plant (WTP) treats water from the Rio Grande River through an irrigation canal jointly operated by Hidalgo and Cameron Counties, WCID No. 9. Originally constructed in 1945, the Westlaco WTP has been expanded three times to meet increased water demands. As a result, the system now comprises four plants, numbered 1, 2, 3, and 4. In the late 1980s and early 1990s, a new 162-acre-foot, raw-water reservoir was built; and the original facility, Plant 1, has been taken out of service; with the Texas Commission on Environmental Quality (TCEQ) dramatically reducing the production rates of the remaining plants respectively.

The project faced schedule challenges from the start. The TCEQ deadline was fast-approaching, and—given the constrained capital improvement program (CIP) budget in the town—it was imperative that the project be built as economically as possible. Moreover, recognizing that local firms has limited qualifications or skills to take on the project, the owner solicited nationally ranked firms, with the intention of building the local economy and local contractors’ skill level through the use of subcontractors on the project in a unique training and mentoring program. Finally, there were hazards that came with working in and around old facility with unknown existing utilities/tie-ins.


The owner proactively addressed schedule and budget concerns by choosing CMAR as a collaborative project-delivery method and structuring the procurement process to give a higher score to firms that incorporated local contractors into their bid packages. By being involved early in the project, CDM Smith was able to help the owner secure much needed bond funding. CDM Smith also helped Westlaco customize the bid packages to maximize local and M/WBE participation –with the result that a significant portion of the construction budget was awarded to local M/WBE firms. CDM Smith geared its team to greater oversight, training and mentorship of the local subs, not just for the trade but also in national health and safety standards.

Improvements include upgrades and hydraulic modifications to the existing three plants to gain 2.18 MGD of additional capacity, as well as a new 8-mgd plant being constructed on the existing site and surrounding area.  The expansion includes adding a treatment structure with a rapid-mix basin, flocculation basins, a sedimentation basin, filters, sludge-handling facilities, clearwell, and a high-service pump station. Other improvements include the addition of a new supervisory control and data acquisition system and major electrical improvements. Improvements to the city’s distribution system include a new 1.0 million-gallon elevated storage tank and over two miles of new 12” and 20” diameter pipelines to accommodate the higher flows.



This $38.5 million CMAR project is currently $2M under budget through 99% buyout, and three months ahead of schedule through 70% completion. The total capacity has increased to 18.3 mgd.