“This is needed generational investment to expand and modernize the Walnut Creek Wastewater Treatment Plant, and it fulfills our responsibility as a city to provide basic but critical services for today, tomorrow and the next 50 years," Mayor Kirk Watson said.
The big picture
The more than $1 billion expansion will boost the plant's wastewater treatment capacity by 33%, from 75 million gallons daily to 100 MGD by the early 2030s. Hundreds of millions of dollars more are also being spent to improve and modernize other parts of the facility, which will remain operational throughout several years of construction.
“This project will be complete in advance of when flows are expected to exceed the plant’s rated capacity in 2032," Austin Water Director Shay Ralls Roalson said. "By expanding the treatment capacity to 100 MGD, we will not only be meeting increasing needs, we will also be able to implement treatment upgrades to meet more stringent regulatory limits on effluent water quality."
The Walnut Creek Wastewater Treatment Plant will remain fully operational during years of construction on expansion and upgrade projects. (Courtesy Austin Water)
The details
On top of the plant's first major capacity upgrade in decades, improvements also include:
Upgrading water treatment processes with biological nutrient removal, which Roalson said will significantly cut the amount of phosphorus and nitrogen discharged from the plant into the Colorado River and improve that waterway's health
Converting water disinfection to an ultraviolet process, eliminating the use of chlorine gas and improving safety
Implementing advanced odor control, such as biofilters and activated carbon filters, which Roalson said will help the plant remain a "good neighbor" in East Austin
Preserving trees and undeveloped areas of the plant property by tunneling a new pipeline to the Colorado River
Rolling out a new treatment process for peak water flows in heavy rain or flood conditions, and building a new flood wall around the property to protect facilities in extreme weather
“This project will modernize every part of the existing plant," Roalson said.
Austin's largest wastewater treatment plant is being expanded and modernized. (Courtesy city of Austin)
Some projects are expected to be completed in the late 2020s, and the 25 MGD capacity increase will be completed by mid-2030. All expansion and modernization initiatives will be completed by late 2032.
The cost
City Council signed off on more than $1 billion in contracted work for Walnut Creek plant improvement nearly two years ago. Earlier this year, they also approved a $600 million addition specific to the expansion. AW officials cited updated plans and increasing construction costs for that change.
In total, major expansion and modernization contracts total more than $1.8 billion. Some of that will be covered through local utility revenue, and millions of dollars in state and federal support also anticipated.
The Texas Water Development Board committed $59 million to the expansion this year, and the utility is expects a low-interest loan of up to $1 billion from the U.S. Environmental Protection Agency.
“Our community benefits tremendously from the economic benefits of partnering with TWDB and EPA on low-interest loans that make these types of investments possible," Roalson said.
