As part of a six-month exploration of the relationship between cities and water, journalist Sarah Goodyear takes a close look at San Antonio in this week’s Forefront, and learns how a fast-growing city on the edge of the desert keeps from exhausting its water supply.
Gregg Eckhardt has the squint of a man who has spent a lot of time outside in the hard sun of South Texas, and the wry smile of someone used to thinking more than he lets on. A senior analyst with San Antonio Water System, he spends his days analyzing, modeling, upgrading and monitoring every aspect of the city’s wastewater recycling program.
“I took the job for the glamour and excitement of working in a sewer plant,” he tells me with that little smile, as we survey the vast, open expanse of the Dos Rios Water Recycling Center.
Dos Rios is about 15 miles from downtown, past the Latino neighborhoods of San Antonio’s South Side, where the sky starts opening up and the city begins to fall away. The open-air facility takes in 75 million gallons of sewage every day. San Antonio, like all municipalities in the nation, must comply with the regulations of the federal Clean Water Act. But what sets it apart from many other cities is the way it uses the result.
After the sewage is cleaned nearly to drinking water standards, it is pumped back out again — some into the San Antonio River, some into the city’s lauded “purple pipe” system. Both uses are important: The treated water that goes into the river helps maintain the flow, and the water that goes into the pipes and gets pumped back to San Antonio keeps the city from using water drawn straight from Edwards for uses that don’t require absolute purity.
“I’m a big fan of the purple pipes,” says Alyssa Burgin, from the Texas Drought Project. “There are so many cities in Texas that could benefit from that.”
Those purple pipes crisscross the city, delivering the recycled water — or “highly treated effluent,” in technical terms — to the Toyota plant for its manufacturing processes, to the Microsoft complex for its cooling towers, to the golf courses for their greens, to the baseball diamonds for their outfields and, most visibly, to the San Antonio Riverwalk, the city’s prime tourist destination.
“It really is the front lines of environmental protection out here,” Eckhardt says. As we step out of the water company SUV, he tells me that he’s just hosted delegations from Mongolia and Korea who have come all this way to see what state-of-the-art water treatment looks like. Then he leads me over to the place where the bubbling brown stew of San Antonio’s waste is entering the plant.
“I want you to see what 75 million gallons of raw sewage looks like,” he says.
We spend the next hour walking from one end of the plant to the other, as Eckhardt explains the process that turns San Antonio’s sewage into clear, clean water every day. The daily load that the plant handles is exactly the same flow as it took in when the plant was built, thanks to conservation measures, even though the population of the city has increased by about 40 percent since then.
“Conservation is a twofer,” Eckhardt says. “You save on the water end, and you save on the wastewater end that you don’t have to treat.”
First, the water is strained through grates that remove the bigger stuff, like condoms, sticks, Doritos bags and, Eckhardt jokes, “Volkswagens.” Then it sits for a couple of hours in huge tanks to let the solids settle before they are sent to a different part of the plant, where they are further processed.
Next, the water is aerated to allow the bacteria that consume the remaining solids to do their work. Those “bugs,” as Eckhardt calls them, are the descendants from a culture that was originally brought to the plant in 1987. Every couple of hours, the plant operators check water samples under a microscope to see if the micro-ecology of the tanks is in good working order.
“Usually if there’s some kind of upset, you can trace it back to some illegal dumping that disrupted the biological process,” Eckhardt says.
Then the water settles and is strained yet again.
As we walk through the plant, swallows swoop and chatter over the bubbling waters. Cattle egrets perch on the pipes, rousing themselves to flap away only when we draw near. There aren’t any people out here with us, except for a couple of brave souls jogging on their lunch hours in the noontime heat. Eckhardt explains that the operation of the plant is completely computerized, run by workers in a small square building amid the welter of infrastructure, where they monitor every valve and pipe from complex computer dashboards.
Dos Rios is a model facility that has evolved over the years thanks to the continuous tinkering and innovations of Eckhardt and his colleagues. “SAWS’ entire operation is based on science,” Burgin says. “It’s so refreshing. It fascinates me how they’re always open to learning about and investing in new technology.”
Many other cities in Texas, she says, don’t have such a flexible, iterative culture. They dig in their heels and keep doing things the same way year after year. “I tell them, maybe you should let down your defenses and look at what [San Antonio] is doing,” Burgin says.