City officials say the infrastructure move is a responsible one because it would prevent a proliferation of smaller plants in the region, but it has alienated some of their former regional allies in bygone environmental battles.
If an expansion is approved by a state environmental agency, something probably years away, the plant could be the second to have a permit to discharge cleaned-up waste water into a Hill Country creek that eventually feeds the Barton Springs portion of the Edwards Aquifer.
Nearly a decade ago, Dripping Springs had teamed up with the city of Austin, the Barton Springs-Edwards Aquifer Groundwater Conservation District and other governmental entities to oppose a similar plant proposed — and eventually built — for Belterra, a burgeoning subdivision just east of Dripping Springs. At the time, Dripping Springs had been a key player in a regional planning effort to manage development.
Now it is Dripping Springs that is considering an expanded plant as it both copes with a growing population and positions itself to recruit new businesses.
Dripping Springs has increased from about 1,500 residents in 2000 to nearly 1,900 in 2012, according to census figures. Roughly 30,000 people live in the wider community around the city.
The existing wastewater treatment plant, built to replace antiquated septic systems, has a capacity to treat 127,500 gallons per day and currently treats half that much.
A year ago, the city’s economic development committee, chaired by former state Rep. Patrick Rose, who runs a title company based in Dripping Springs, declared in a letter to the mayor that the lack of capacity undermines the city’s ability to meet the needs of existing residents, manage new growth and to “recruit additional, quality primary employers to our community.”
The city then hired an engineering firm. Using what it says is a moderate projection — an annual growth rate of 8 percent — the firm forecast in a $94,000 report that the plant will reach 90 percent of its capacity by 2017, and that by 2023 it will have to treat 199,615 gallons per day.
The city currently uses treated wastewater to irrigate city-owned land. The engineering firm recommended expanding the plant to a capacity of 750,000 gallons per day. Treated wastewater could be sprayed on city-owned playing fields and land at new subdivisions tying into the plant, but the engineering firm recommended also seeking permission from the state to discharge into Onion Creek. The direct discharge permit would give the plant another option for handling cleaned-up sewer water in case it outstrips the demand to irrigate neighboring lands.
City Council member Bill Foulds said a centralized plant run by the city will cut down the risk from Belterra-like plants scattered around the Hill Country. Providing wastewater services to subdivisions in its suburbs also gives the city some leverage in managing development, such as requiring construction setbacks from area waterways. The new developments would pay for the lion’s share of the plant expansion, which will likely be more modest than the $28.6 million expansion envisioned by the engineering firm, he said.
Under state standards, the effluent should be clean enough to fish or swim in.
Salt Lick restaurant owner Scott Roberts, whose family has owned property fronting Onion Creek since 1902, says he is not concerned about potential treated sewage discharges upriver of him — as long as it is treated properly.
“Right now I’m comfortable with the motivation and intentions of Dripping Springs,” he said. “They’re not out there to create a sea of concrete. They really are committed to making sure development in their jurisdiction takes place conscientiously.”
Austin officials are monitoring the plant expansion prospects.
“It’s great they’re looking forward to plan infrastructure to facilitate growth,” said Chris Herrington, a city of Austin environmental engineer. “But the question is, are they rushing to make decision that would be controversial for a lot of people?”
If the Belterra scenario plays itself out again, downstream cities, residents or environmental groups could contest the discharge permit before it wins approval.
“There’s a huge potential for disastrous water-quality impacts,” Herrington said.