“Travel to places few people have ever visited,” is a phrase from San Antonio Water System’s (SAWS) website describing the Rain to Drain Experience. The Rain to Drain Experience is one of many educational programs SAWS conducts. SAWS is accountable for hundreds of millions of dollars of public money, charged with supplying clean water to 1.7 million people in Bexar County, and responsible for treating wastewater to ensure the health of the residents. These goals require SAWS generate public awareness of its function and approve of its effectiveness; the Rain to Drain Experience helps fulfill that goal.
Several times a year SAWS conducts Rain to Drain tours of the water system infrastructure. Our tour started at SAWS Headquarters with the first stop at Bear Cave in Stone Oak Park, one of many locations where rainwater recharges the Edwards Aquifer. The tour proceeded to a well and pump station that serves approximately 250,000 people. The nine-hour, 100-mile tour concluded at the Dos Rios Water Recycling Center where clean water is returned to the Medina River.
The tour turned out to be an intensive, compressed study of San Antonio’s water system. Greg Wukasch and Lynne Christopher, the SAWS education staff, educated, entertained and answered a variety of questions from the 40-plus attendees. The education staff primarily conducts programs for schools to educate students about the basics of our water system in order to become more informed citizens. The Rain to Drain Experience is one of the few programs geared to adults with a specific goal elicited, which I will note later. SAWS relies on word-of-mouth publicity for the Rain to Drain Experience, which seems successful since the tour is fully reserved for October and November with only a few slots remaining in December. The 2016 schedule is not set at this time.
The group learned where our water comes from, how it is distributed to more than 1.7 million people and where it goes after we flush. We learned that SAWS is an award-winning water system and its customers are conscientious users of a very precious commodity. Water use in San Antonio has been reduced over the years as customers have become more aware of the limited supply and many available conservation methods.
SAWS has an annual budget (page 21 of 2015 budget) of approximately $265 million for operation and maintenance, $13 million transferred to the city, debt service of $188 million and other charges for a total of $579 million. SAWS serves the needs of 1.7 million people and is estimated to deliver 55.5 billion gallons of water in 2015. I am not an accountant or a mathematician, but I think that comes out to be less than 10 cents a gallon of water, considerably less than bottled water. San Antonio boasts the second lowest rates in Texas of cities with more than 500,000 people, right behind Fort Worth and significantly lower than third place Austin.
Where Does Our Water Come From?
Most residents know that most of our water comes from the Edwards Aquifer. The average citizen might describe the aquifer as a giant underground well, but nature has engineered something much more complex and beautiful, even if we can’t see it. The aquifer is a natural, underground limestone structure stretching from Austin to Brackettville and is composed of four distinct zones: contributing, recharge, transition and artesian, and artesian. Read more about the Edwards Aquifer on the Edwards Aquifer Website and Edwards Aquifer Authority.
The tour visited one major recharge feature of the Edwards Aquifer, Bear Cave, the largest recharge cave in San Antonio, its entrance covered by a steel grate that prevents people from entering the cave. Recharge caves and other ground features allow rainwater to seep into the ground and replenish the aquifer rather than flow downstream and be lost as a water source. An earlier steel grate was destroyed by flooding and replaced by a more substantial structure that has yet to be tested. The Hill Country has numerous recharge caves and Bear Cave is just another ordinary recharge cave, although to the average citizen it appears unique. A visit to Cascade Caverns or other public caves would reveal the interior features of recharge caves. At Stone Oak Park, dry creeks are visible with fissures that allow water to enter the aquifer. Hundreds of exposed karst limestone rocks show visible geological features that allow limestone to “hold” water like a sponge.
SAWS purchased the property to protect the site and deeded it to the San Antonio Parks and Recreation Department, which allows the land to be used by the public as a park while protecting the recharge function. Some flood control dams in the area serve dual purposes: one is to prevent downstream flooding and damage, and the second is diversion of water to a recharge feature.
The group got a closer view of a recharge cave at the smaller Cub Cave in Stone Oak Park. Our guide pointed out various features in the cave and noted rock-climbing carabiners attached by local climbers. Cub Cave was used by the San Antonio Fire Department to practice underground rescues until a roof collapse during an exercise forced a stop to that activity. The roof collapse demonstrates that these caves are can be dangerous for curious amateurs.
How does the water get to our homes?
Six well and pump stations are located at various sites in San Antonio. Several well pumps at each site feed water to a five million gallon storage tank where massive pumps force water to more than 200,000 people through a complex piping system. The water coming out of the well is safe and drinkable without treatment; chlorine is added to prevent bacterial growth as the water travels from the pump station to the end-user. Fluoride is added to the water as a public health measure; the citizens of San Antonio approved the addition of fluoride in 2000 and SAWS added fluoride to the water in 2002.
The well and pump stations are controlled through a radio system from the main office location with a duplicate backup system located offsite. Due to security concerns the tour was not permitted in the control room. It was strange to visit a massive pump room and below ground pipe distribution system and not see a single worker. Our tour guide assured us that there was visible monitoring of our movements.
Where does water go when we flush?
The final stop of the day was the Dos Rios Water Recycling Center. We were warned to expect a harsh aroma at the plant upon arrival and it was suggested that we spray hand sanitizer on our hands, shirt collars and face to alleviate the smell. It was a relatively cool day with a slight breeze and the warnings were not needed. Our guide told us that on hot, humid, windless days the smells would be more noticeable. While the aroma was tolerable, the sights of solid materials being skimmed off were unusual.
Wastewater is not merely treated and released to the river at the plant. At the Dos Rios facility wastewater is recycled into three major products before clean water is discharged into the Medina River. One of the products is clean water; some of the water ends up in Calaveras and Braunig Lakes. CPS Energy uses both man-made lakes for cooling power generation equipment and by the public as recreation facilities.
The second byproduct is biosolids. Biosolids are removed through screening and settling processes. The biosolids stay in tanks for about 30 days to dry and be digested by bacteria. The biomass is then sold to a local company and turned into compost for landscaping.
SAWS began to recycle methane gas that was formerly burned off as a waste product in 2010. Ameresco contracted with SAWS to process methane gas and sell it on the open natural gas market. The methane is produced during the anaerobic action of the biosolids creation.
Challenges for the future
SAWS is faced with three major challenges. One of the reasons SAWS conducts Rain to Drain tours is to educate the public about the challenges ahead. First, the infrastructure is aging and replacement is a constant and expensive activity. Pipes break due to shifting soil, age and water pressure. Replacement is expensive and new methods are continuously reviewed. One new technique of insertion of a polymer inside a pipe, which then hardens and expands, is being evaluated.
The second major challenge is the sanitary sewer system is being stressed by numerous causes. One cause is the insertion of materials into the system that are not biodegradable. An example is the increase in the amount of personal wipes being flushed down the toilet. These products are flushable, but not biodegradable. They catch on roots, solid objects and create blockages in the sewer lines, which then cause backups of sewage into homes. SAWS is very concerned about the types of solid objects that end up in the wastewater treatment plants. Grease and solid object disposal is a major problem causing blockages that are difficult to remove. Grease, personal wipes and other solids should not be flushed down the toilet or sink; these materials should be put into the garbage or organic items could be used for compost. SAWS is working with major retailers to address the issue of labeling these products so the public is aware they are not biodegradable.
Flooding also is a major concern. Floodwaters flow into storm drains at times and cause problems. While SAWS and its customers can’t control the rain they can work on flood control projects through the city and San Antonio River Authority.
The final major challenge is keeping up with growth. Education of the public creates an informed citizenry to work with SAWS and elected officials to better manage growth. Some of the ideas and plans for future growth require an informed public to understand and support, or to challenge. The Vista Ridge Pipeline, which will pump water from Burleson County to San Antonio, is one such example of a politically charged project with pros and cons.
Recently SAWS announced plans to extend water service to Camp Bullis, Lackland Training Annex, Lackland Air Force Base, Security Hill and Fort Sam Houston to help these facilities solve water issues. The hope is that these actions will help keep the bases in San Antonio.
Another less known project is the Twins Oaks Aquifer Storage and Recovery project, which “banks” Edwards Aquifer water for future use. SAWS buys water in advance from the Edwards Aquifer Authority for future use; if the water is not pumped and used it is lost. Water is pumped into the Twins Oaks Aquifer during the year, storing it underground and pumping it out when needed.
The tour allowed me to become a better water customer. If you can’t make the tour I suggest you visit the SAWS and Edwards Aquifer websites to become a better water user, and a better citizen of the region.
*Top image: Sampling water directly from storage tank. Photo by Warren Lieberman.