What's happening
Multiple contracts for the Walnut Creek Wastewater Treatment Plant's expansion and enhancements were approved by City Council on May 30.
The Walnut Creek facility is located on the far east side of the city and treats more than half of Austin's wastewater, about 60 million gallons per day, or MGD.
The plant has been in service since the late 1970s when it opened with a capacity of 18 MGD. It eventually reached its capacity of 75 MGD over decades of expansion and improvements.
The utility is now moving to increase the Walnut Creek plant's capacity up to 100 MGD along with other improvements and rehabilitation work.
The majority of Austin's wastewater is treated at the Walnut Creek plant, while the utility's South Austin plant also has a 75 MGD capacity and handles an average flow of 40 MGD. Several smaller AW facilities see a combined flow of about 2 MGD.
The breakdown
New spending approved May 30 for wastewater facility improvements totaled $1.13 billion, including:
- A $900 million contract with MWH Constructors Inc. and an additional $71 million to AECOM Technical Services Inc. for the expansion of the plant's capacity to 100 MGD
- An additional $127.3 million for a contract with MGC Contractors Inc. and $17 million for a contract with Black & Veatch Corp. to rehab the plant's primary clarifier and basin, which treat wastewater
- An additional $9 million for a contract with Carollo Engineers Inc. to rehab the plant's headworks, which treats initial wastewater coming into the facility
- An additional $2.85 million for a contract with CDM Smith Inc. to replace a drain and lift station handling some of the plant's wastewater
Notable upgrades include the additional capacity, the disinfection and treatment system modernizations, and the construction of a flood protection wall around the plant.
Improvement projects are expected to begin next year and wrap up by 2031. The facility will continue to operate while construction takes place in "every area of the plant," according to AW.
“With these investments, every part of the treatment process will be enhanced and upgraded, and we will be prepared to serve the growing needs of our City,” AW Director Shay Ralls Roalson said in a statement. “Austin Water’s management and stewardship of Walnut Creek Wastewater Treatment Plant and our wastewater infrastructure generally is one of our most important environmental legacies."
The cost
AW is anticipating its rates could rise about 30% over the next four years.
The utility is conducting a cost-of-service study and gathering community input ahead of the hikes. AW officials said some, but not all, of the customer billing increases will help cover the costs of the Walnut Creek projects.
“We haven’t had rate increases, certainly not at this level, in a long, long time," Roalson told city leaders in early May.
The treatment plant expansion has been in planning for years through the utility's long-range spending plan ahead of the projected rate adjustment.
Officials have said the upgrades are needed in part to meet service needs and state standards for wastewater facilities, although the new capacity likely won't be reached for at least two decades.
"Based on regulatory triggers from [the Texas Commission on Environmental Quality], Austin Water is required to begin design work for an expansion when 75% of capacity is reached and begin construction when 90% of capacity is reached. Austin Water has planned the expansion of Walnut Creek Wastewater Treatment Plant in response to these regulatory triggers," spokesperson Emlea Chanslor said in an email.
Quote of note
"While we anticipate that rates will need to be increased in the coming years, we are committed to setting a rate structure that achieves a balance between affordability, equity, conservation, financial responsibility and resiliency. We have not set rates at this time and are asking for input from our customers about the best way to structure them to cover rising costs and make necessary system-wide investments, such as the expansion and improvements to the Walnut Creek Wastewater Treatment Plant," Chanslor said. "We will not set rates until we’ve heard from as many as possible as part of this process."
