City IDs, pursues next water supply
The City of San Angelo has identified the leading option for its next water supply and taken the first step toward its development.
The Concho River Water Project is a move to extend San Angelo’s sources beyond its lakes and the Hickory Aquifer. It will do so by adding a reliable and sustainable source that will help meet water needs for decades to come.
The project involves releasing highly treated water from the City’s wastewater treatment plant into the Concho River. After it has flowed down that “natural pipeline,” the water will be recouped farther downstream. From there, it will be piped to the water treatment plant, where it will be treated to drinking standards.
“This is water San Angelo already has,” said attorney Jason Hill, the City’s special counsel for water. “We’re just able to make better use of it. It’s a win-win for the community.”
On Sept. 18, the City Council unanimously agreed to pursue state permits that will ensure the water is treated to adequately high standards before its release into the river.
Prior to recommending the Concho River project, engineers and City staff studied 24 possible water supplies. Those included surface water, groundwater and direct reuse. The experts and City officials concluded the Concho River Water Project is a reliable and cost-effective source, will produce water with an improved taste, can be developed relatively quickly, and utilizes proven science. Cities have long released their treated wastewater downstream into streams, rivers and lakes. Treated wastewater from Ballinger, Robert Lee and Winters, for instance, flows into San Angelo’s primary water source, Ivie Reservoir.
“We are releasing it into the Concho so we have what we call an environmental buffer,” said Scott Hibbs, principal water resource engineer with eHT, an Abilene engineering firm. “So we’re letting Mother Nature take care of some of the treatment aspects.”
Securing state permits could take as little as two to three years. Completing the entire project could take about five years and will cost about $120 million dollars. That includes upgrades to the water and wastewater treatment plants. Those improvements would be needed regardless of which new water source was chosen.
When completed, the Concho River Water Project will produce about 7.5 million gallons per day. By comparison, the Hickory Aquifer is currently capable of producing 8 million gallons per day, although that is being expanded to 12 million gallons. San Angelo averages about 12 million gallons of daily usage.
Work continues by the West Texas Water Partnership to develop a long-term source that can serve San Angelo, Abilene and Midland. The Concho River Water Project will help meet local water demands for about the next 50 years.
“This takes San Angelo a long ways down the road of water security,” Hill said. “And when I say a long ways, I’m talking generationally … 2060, 2070.”
The project will also diversify San Angelo’s portfolio of water sources. Because the City will not be dependent upon any one source of water, San Angelo will be better able to weather times of drought.
The Water Reclamation Facility treats wastewater from the City of San Angelo to remove pollutants and to produce an environmentally safe water that meets state permit requirements.
All of the reclaimed water is utilized for irrigation. The water is either used to irrigate the City's farm or provided to the Tom Green County Water Control and Improvement District No. 1 for irrigation for its members. Below are the operations managed by the Water Reclamation.
The wastewater treatment plant is a conventional activated sludge treatment plant that treats an average of 9 million to 10 million gallons per day. The plant uses three anaerobic digesters for sludge stabilization. The treatment process consists of six steps:
- Lift station: All of San Angelo's wastewater flows into a wet well located at the wastewater treatment plant. The wet well contains large pumps that pump all the wastewater to the head works of the plant.
- Mechanical bar screens: There are two mechanical bar screens located at the beginning of the head works. These bar screens are set on times to operate every 15 minutes. The bar screens have square tubing spaced approximately 1 inch apart. Any large rags or debris is stopped by these bar screens. The bar screens have large mechanical rakes that clean the debris off the bars and deposits them into a dumpster for disposal in the landfill.
- Grit removal: There is a grit removal system after the wastewater goes through the bar screens. Here sand, gravel, etc. are removed from the system and taken to the landfill for disposal.
- Primary clarifiers: There are four primary clarifiers that slow the flow of the water to allow fine particles to settle out. The sludge that settles to the bottom of the clarifiers is pumped to the digesters for stabilization. The effluent from the primary clarifiers flows into aeration basins for further treatment.
- Aeration basins: There are two aeration basins. Each basin contains more than 3,000 ceramic fine bubble diffusers. The diffusers act just like an air stone in a fish tank. Air flows through the diffusers to provide oxygen for the aerobic bacteria in the aeration basins. The aerobic bacteria thrive in the presence of oxygen and feed on the organic matter in the water, thus removing pollutants in the water.
- Final clarifiers: There are four final clarifiers that slow the flow of the water to allow the sludge from the aeration basins to settle out. The sludge settles to the bottom of the final clarifiers, where most of it is recirculated to the aeration basins to maintain an adequate level of aerobic bacteria. The cleaned wastewater flows into a wet well for pumping to the holding reservoirs. The water from the reservoirs is either pumped to the Tom Green County Water Control and Improvement District in Veribest for irrigation or is irrigated at the City's farm.
City Farm is located adjacent to the Water Reclamation Facility. It consists of approximately 2,463 acres that are leased for agricultural production.
The farm contains two effluent holding reservoirs that have the capacity to hold approximately 1 billion gallons of reclaimed water. An irrigation pump station is located adjacent to the reservoirs. The station pumps the water to either the Tom Green County Water Control and Improvement District's canals or to the farm's distribution system. All of the reclaimed water is utilized by irrigation.