Water Reclamation in the Rio Grande Valley

McAllen utility jumps on opportunity to deliver reclaimed water to residential customers.

Water Reclamation in the Rio Grande Valley

McAllen Public Utility heavy-equipment operator Manuel Peña Jr. (left) and lift station operator Andres Zamora flush out a sewer line with a Vactor 2100i jet/vac truck. (Photography by Verónica G. Cárdenas)

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McAllen Public Utility believes in second chances. Specifically, the south Texas community is fully committed to the notion that wastewater shouldn’t be wasted as a resource.

In 2020, the utility broadened its vision and applied the principle to a new category of reclaimed water customer: residential property owners.

McAllen is a Rio Grande Valley community across the river from Reynosa, Mexico. The semiarid region mostly has an agriculture and border-trade economy. Neighboring farm fields and the green spaces inside the city are irrigated during long, hot summers to supplement the 22 inches or so of annual rainfall.

The catalyst for the expansion of reclaimed water use was Tres Lagos, a new and growing residential development on the north side of the city. Opened three years ago, the master-planned community eventually will contain 5,000 residences along with such amenities as a 1,000-student IDEA public school and a satellite campus of Texas A&M University, College Station.

Developer Mike Rhodes, co-founder of McAllen-based Rhodes Enterprises, approached the city in 2014 about using reclaimed water to irrigate private and common properties in the 2,500-acre development. The city was immediately interested in supplying the reclaimed water for a new residential population that eventually will number 80,000 people. In 2015, McAllen decided it wanted to be the first in Rio Grande Valley to offer reclaimed water to residential properties.

Yet the Tres Lagos proposal posed difficulties. “The issues were that the development was on the north side near the north wastewater treatment plant and most of the wastewater flowed to the south treatment plant,” says David Garza, McAllen’s director of wastewater systems. The other problem was that the bulk of reclaimed water at that time was already spoken for. For two decades, some 1.5 billion gallons per year had been routed to cooling towers at a Calpine electrical power company plant.

The utility was distributing its treated water according to a master plan completed in 2016 that focused on south-side utilization. Other than the cooling tower destination, treated water flowed to parks and a 200-acre municipal golf course — all on the south side. Says Garza: “When the Tres Lagos developer approached us, everything got turned around.”

Diverting flow

The master plan that focused on the south plant nevertheless remained key because it contained ideas about how to divert water north. Reducing the flow to the south treatment facility had been on the minds of planners because the plant needed upgrading. “The south treatment plant needed major repairs and the less wastewater it received the better,” Garza says.

So, McAllen Public Utility engineers pursued the idea of rechanneling a million gallons of collected wastewater per day from south to north to more easily serve the proposed Tres Lagos project. The first step was laying 6 miles of 12-, 16- and 24-inch gravity line. The new line rerouted the wastewater to a lift station that could feed it northbound. Four other stations were eliminated by the redirection.

A Texas Commission on Environmental Quality requirement that reclaimed wastewater for residential property meet the standards of Type I water created a second obstacle. Up until that point, McAllen had distributed only Type II second-hand water.

The difference in the two types is the acceptable level of turbidity and E. coli. Most E. coli strains are harmless, but some cause diarrhea, cramps and a low-grade fever. To remove that threat, the north plant was fitted with an Aqua-Aerobic filtration system to reduce the volume of matter suspended in the water.

Fortunate funding

All this work to redirect wastewater began in 2016 and was completed three years later. The price tag for the new collection line and treatment plant upgrade along with the new distribution pipeline running to Tres Lagos was $8.3 million. The utility secured a low-interest loan from the Texas Water Development Board, with $1.25 million of that being forgiven because it was a green project. Because the utility was partnering with Tres Lagos, which had qualified as a Tax Increment Reinvestment Zone, another $4.5 million was reimbursed to the utility.

“The reimbursement and forgiveness accounted for nearly 75% of the cost of the project,” Garza says. “That was great for McAllen Public Utility. It now would have two major customers accepting reclaimed water and increasing the utility’s revenue stream, and it all would happen without creating a financial burden for our ratepayers.”

Residents got a water rate increase last October, but the rate remains relatively low. Rates are tiered for potable and reclaimed wastewater. For example, the base rate for all water is $9.95 per month. Potable water costs $1.45 per thousand gallons used up to 8,000 gallons, with rates increasing according to usage. Reclaimed wastewater is $1.16 per thousand gallons regardless of volume used.

Paying dividends

The rest of the story, of course, is the amount of potable water not used. Two pipelines run about 5 miles from the north plant to Tres Lagos, one carrying potable water, the other reclaimed wastewater. When all 5,000 homes are built and occupied, some 180 million gallons of reused water will be piped to the development each year to irrigate lawns, parks and ballfields. That is in addition to the 1.5 billion gallons of reclaimed water utilized by the Calpine power plant and 530 million gallons soaked up by the city golf course.

In other words, millions and millions of gallons of drinkable water would be growing that grass and cooling that electricity production process if reclaimed water was not available. Garza estimates that 20,000 gallons of potable water is saved per month at each home in Tres Lagos because reused water is available for irrigation.

“The Tres Lagos project will pay future dividends, conserving more than 30 million gallons of potable water each month during the next three years. By 2035, it’s estimated more than 67 million gallons will be conserved each month. This utility continues to set the example across the valley in water recovery and conservation.”

Across the system

Garza became wastewater director at McAllen Public Utility in 2016 after more than 18 years in similar work in Pharr, a neighboring Hidalgo County community. He oversees a department that handles much of its infrastructure maintenance in-house. Major system expansion and rehabilitation projects are bid out.

“Our employees generally are cross-trained but we have a construction crew, three or four guys, who do the repair work,” he says.

They have a couple John Deere 310K backhoes to uncover leaking lines. Four Vactor 2100 hydrovac trucks are called to perform more delicate excavation or when a line needs a 2,500 psi blast to clear it.

Two crew members specialize in CCTV inspection work. To peer into clay pipes that average 40-plus years in age, or new HOBAS Pipe USA GRP (fiberglass-reinforced pipe) lines, they use a Trio-Vision USA TVT-300 steerable inspection crawler system. Pipelines in the system range from 6 to 54 inches. An Xplorer camera (also from Trio-Vision) on a telescopic pole is employed for brick or concrete manhole inspections.

The utility is methodically re-engineering the system’s hydraulics wherever it can to allow for gravity flow of the wastewater. The biggest recent project of that kind eliminated two lift stations and abandoned a ductile iron force main. The $4.6 million project replaced that infrastructure with 6,800 feet of 48-inch Hobas GRP that was buried 30 feet deep at one point.

“Ductile iron is not the norm in this part of the country,” Garza says, noting that the project likely eliminated the last of that type of pipe, which had not functioned well for the city.

As for the Tres Lagos project, the wastewater director is satisfied not only with the outcome but the process that made it happen. “The public-private partnership was a fantastic deal for McAllen, for the developer and for ratepayers. The vision was there and the master plan was there. We will be able to serve close to 80,000 people out there and avoid using millions of gallons of potable water in serving them.” 


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