The Austin City Council approved last Thursday contracts to complete the design and construct significant enhancements and expansion of the Walnut Creek Wastewater Treatment Plant, totalling over $1 billion.
Under the approved contracts, construction is expected to begin in 2025 on an expansion to add a treatment capacity of 25 million gallons per day to serve population growth. The existing plant is currently permitted to treat 75 million gallons per day.
In addition, significant enhancements and modernizations will rebuild or replace ageing parts of the existing plant and will incorporate improved operational and environmental features plantwide.
The project will replace the disinfection system to use ultraviolet (UV) light, which will eliminate the use of chlorine chemicals for disinfection and will make the plant inherently safer for workers and the community.
The treatment process for the existing plant and the expansion will be upgraded to reduce the nutrients that contribute to algae growth and blooms to benefit the health of the Colorado River downstream of Austin. To improve the resiliency of the plant, a wall will be built around the plant to protect it from floodwaters.
This construction will occur in every area of the plant, and all construction will be completed while the plant continues to operate. Considering the complexities of operating the plant during construction and rehabilitating components that are nearly 50 years old, a collaborative delivery method known as Construction Manager at Risk will be used. This method allows the contractor to be hired earlier and contribute to the design process in key areas, including constructability, maintenance of plant operations, scheduling and coordinating work packages, and cost control.
“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,” said Shay Ralls Roalson, Director, Austin Water.
“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,” said Roalson. “Because of the careful planning and around-the-clock efforts of our workforce, Austin Water will continue to provide this vital service in a responsible manner.”
History of Walnut Creek Wastewater Treatment Plant
- Built in 1977 (18 million gallons per day capacity)
- Expanded in 1987, 1990 and 2005 to reach current capacity of 75 million gallons per day
- 2013 – 2024 $100 million invested in replacement and upgrades at the plant
Project Cost Overview (amounts are approximate):
Renewal Projects - $270 million
- $160 million – Rehabilitation of Primary and Flow Equalization Basin Rehab
- $90 million – Rehabilitation of Headworks #1
- $20 million – Replace and upgrade Influent Lift Station
Expansion Projects - $440 million
- $380 million – 25 MGD Capacity Expansion with nutrient removal and UV disinfection
- $60 million – New influent and outfall pipelines
Treatment Conversion Projects - $220 million
- $220 million – 75 MGD process treatment conversion to nutrient removal and UV disinfection
Protection of Plant Projects - $120 million
- $80 million – Wet Weather Facility for high flows during rain events
- $40 million – Flood Wall around plant
