For more than 20 years the Public Utility Board of the City of McAllen, Texas, has invested in using reclaimed water to conserve potable water. McAllen, which is in Hidalgo County in South Texas in the Rio Grande Valley bordering Mexico, has a population of roughly 146,000 and began providing reclaimed water 20 years ago to an electrical power company for its cooling towers and to irrigate a local golf course. Many communities in Deep South Texas that produce reclaimed water use it for these reasons, as the cost of producing potable water in the drought-prone region is higher. In recent years, McAllen sought to expand its water portfolio further.
The McAllen Public Utility (MPU) operates the city’s water and wastewater infrastructure. On the drinking water side, McAllen’s two water treatment plants have a minimum daily production capacity of about 58 MGD of water. The utility also operates a 1.4 MGD groundwater well, which give McAllen’s water system the capability of producing approximately 60 million gallons per day.
On the wastewater side, MPU’s wastewater system serves more than 200,000 people a day, which includes a small neighboring city, Alton, Texas. Its approximately 41,500 accounts include residential, commercial and industrial customers and the utility operates two wastewater treatment plants: North (15 MGD) and South (10 MGD). The utility’s wastewater collection system consists of 55 lift stations, 8,500 manholes and 570 miles of 6- to 54-in. sanitary sewer lines.
Background
With the Rio Grande Valley prone to droughts, the City of McAllen Public Utility has always been a leader in the conservation of water and understood that diversity in the water portfolio was important for today and the future.
In 2014, MPU was approached by developer Tres Lagos, which was developing a residential space to the north and asking for reclaimed water for the homes on the development. This development would include more than 5,000 homes, IDEA school, a Texas A&M Campus and parks. Once complete it would have a residential population of approximately 80,000. If McAllen were to undertake the project, it would make the development the first of its kind south of San Antonio to receive reclaimed water for residential irrigation.
According to Tres Lagos developer Mike Rhodes, residential developments in the region use about half the water needed for agriculture, so water for irrigation is huge consideration. “If we add reuse to the equation, we use half of that,” he says. “So, we’re building a community that’s using one fourth of what the [agriculture and farm land] does.”
The challenge was that the Tres Lagos development was on the north side of the utility and most of the reclaimed water delivered to the electrical power company – and most of the wastewater – flowed to the MPU’s South treatment plant.
In 2015, the MPU Board made the decision to undertake a project to deliver reclaimed water to the residential homes at Tres Lagos, making it the first in the Rio Grande Valley that would distribute reclaimed water to a residential area.
By 2016, MPU had a Reclaimed Water Master Plan completed and the plan had a suggestion of how to distribute the water to the north from the southern part of McAllen. MPU would need to ensure the infrastructure was in place to serve the new development and that the North wastewater treatment plant was producing a Type I reclaimed water. The goal of the project was not only to supply the Tres Lagos development but also offset the cost of the use of potable at the location, thus conserving drinking water while saving money.
How They Did It
MPU engineers carefully analyzed the Master Plan and decided it was feasible to reroute the wastewater from the south to north. At major lift station that was collecting more than 1 MGD of wastewater, the force main was reroute to nearby manhole that was routed to 15 MGD North Wastewater Treatment Extended Aeration Plant. The North wastewater treatment plant was averaging about 7 MGD. With the additional flow coming, a huge increase was needed to be able to produce and distribute to two customers. As it turned out, it was a great decision to reroute the 1 MGD of wastewater from the south to the north because the South treatment plant needed major repairs and the less wastewater it received the better at the time.
The next step was the North treatment plant needed to produce a Type I reclaimed water – at the time, it was producing a Type II. The Texas Commission of Environmental Quality (TCEQ) requires a Type I reclaimed water to provide to residential homes. A filter system had to be designed and constructed for the North treatment plant to lower the turbidity to produce a Type I reclaimed water. All other TCEQ parameters were already being met.
New systems installed at the North wastewater treatment plant included a new cloth filter system which will eliminate floating solids, reduce suspended solids, turbidity and fine particle in the NWWATP effluent to produce a cleaner Type I reclaimed water for customers.
Furthermore, the transmission and distribution infrastructure to the development had to be designed and installed. All told, the project included more than four miles of 12- to 16-in. diameter reclaimed water transmission pipe that would deliver the Type I water to the Tres Lagos community, Texas A&M University campus and a McAllen youth baseball complex. The reclaimed water system essentially acts as a dual system to the potable system in place for the entire complex.
According to McAllen Public Utility Board trustee Charles Amos, McAllen is now the largest distributor of reused water in Texas south of San Antonio. “To have seen the progression of technology 15 years ago to where we are at today, to have culminated in a project such as this, we are going to have 5,000 homes with dedicated meters using reused water [for irrigation],” he said.
Funding
The total for both the treatment facility upgrades and the distribution infrastructure was $8.3 million.
MPU teamed up with the developer of Tres Lagos, who had received a Tax Increment Reinvest Zone (TIRZ) for his development from Hidalgo County. MPU received a very low interest loan from the Texas Water Development Board (TWDB) of $8.3 million and received a loan forgiveness from TWDB of $1.25 million for it being a green project. In addition, McAllen received $4.5 million from the TIRZ in return for its investment in infrastructure. Together, the loan forgiveness and TIRZ reimbursement represented close to 75 percent of the total project funding. This was great news for MPU because not only would it have two major customers accepting reclaiming water, it would also increase its revenue stream without creating a financial burden for ratepayers.
In February of 2019, all infrastructure needed to produce and distribute Type I reclaimed water was in a place. A ribbon cutting was held at the NWWTP to celebrate the partnership between the developer and MPU.
McAllen is the first Rio Grande Valley city to create a residential reclaimed water irrigation program to conserve potable water. Now with more than 450 homes already built and developer goal to build 150 new homes per year, with IDEA School System and Texas A&M Campus already up in running and Tres Lago green space receiving reclaimed water for irrigation.
Every residence will come equipped with a reuse meter and the reclaimed water is expected to save every home 180,000 gallons of water per year and, overall, saving 1.5 billion gallons of potable water annually.
According to MPU, by 2035 the utility will save more than 67.1 million gallons per month in water conservation in addition to more than 1 billion gallons per year of reclaim water already being distributed to the electrical power company.
“This project has been years in the making. The passion of our staff and the passion of our directors is why we were successful,” says Marco Vega, general manager of MPU.
The City of McAllen Public Utility continues to be first in the Rio Grande Valley in setting example in water recovery and conservation.
This article was developed by David Garza, director of wastewater systems for McAllen Public Utility, and WF&M staff. Garza has more than 20 years of experience in municipal wastewater management. MPU operates the City of McAllen’s water and wastewater infrastructure, serving a population of roughly 146,000 in the Rio Grande Valley.
