General Contractor MWH Constructors Inc.
 

After decades of political, funding and environmental challenges, Austin’s Water Treatment Plant No. 4 was completed, commissioned and started up in November 2014. The plant can treat 50 million gallons per day of wastewater with expansion capability to 300 mgd. The facility includes an intake system in Lake Travis, a raw water tunnel and pump station, a treatment plant and the Jollyville transmission main.

With multiple components, the city of Austin chose the construction manager at-risk method to keep all segments in a single contract, making this one of the largest CMAR projects in Texas.

Accessibility to the lake was extremely difficult, given the massive equipment needed for construction and the lack of nearby staging. Working together, the team developed a plan to stage the lake tap from Mansfield Dam, located relatively close to the intake. It was then lifted off the dam with a 300-ton derrick barge.

Creating the foundations to support the raw water intake screens was a challenge as well. The team collaborated on constructibility of the foundation during the design process, then asked contract bidders for additional valueengineering ideas. One of these ideas was implemented— using piles drilled into the underlying limestone to support the intake screens instead of the mat foundations that were originally planned.