Water Treatment Plant 4 Final Design

City of Austin, 
Texas

Water Treatment Plant 4 Final Design

Project Highlights: 
  • New 50 million gallon per day (MGD) water treatment plant (300 MGD buildout)
  • Design includes several miles of new tunnels, including a raw water tunnel more than 350 feet deep.
  • Use of lime softening takes advantage of an abundant local resource.
  • Occupied buildings using green technology to achieve a LEED rating of Silver.
  • Rainwater harvesting reduces runoff and maximizes efficient water use.

The City of Austin hired Carollo to perform the preliminary design, final design, and construction management services of a new water treatment plant (WTP4). The initial plant capacity will be 50 mgd, and the facilities will be sized and configured for an ultimate capacity of 300 mgd. A submerged intake in nearby Lake Travis will draw water from the lake, which will then flow through a 350-foot deep, two-mile tunnel to a raw water pump station and then be lifted to the WTP4 site. The water will be treated using lime softening, granular media filtration, UV disinfection, and chloramination. WTP4 will be built on a challenging hillside site in a sensitive environmental area, requiring the implementation of a rigorous process to implement best management practices and environmental mitigation measures. Carollo completed preliminary engineering and moved into final detailed design of the facility in 2008. Initial phases of roadway and pump station construction were started in 2009, with construction of the water plant facilities that began in 2011. Carollo’s services consist of the following tasks:

  • Develop and conduct a broad-based communications plan to involve key stakeholders.
  • Develop mitigation measures and environmental enhancements for construction of the new WTP4.
  • Assist in alternative site assessments conducted by the City and others.
  • Perform additional environmental surveys and monitoring to enhance the existing database of information and secure permits for the various phases of the work.
  • Develop alternative layouts for the potential sites that reflect current concepts for mitigation and plant size.
  • Benchmark this project to other projects developed in environmentally sensitive areas.
  • Perform hydraulic modeling and distribution system analysis.
  • Complete design phase services, including multiple hydraulic structures and buildings, new roadways and piping systems, environmental protection features, a new electrical substation, and security improvements.
  • Provide construction and startup phase services.