Lake Travis Raw Water Facilities

Project Narrative

The projected growth of the greater Austin area requires a reliable drinking water supply and treatment system. This need led to the development, design and construction of the Lake Travis Raw Water Intake and Water Treatment Plant (WTP) No. 4. An integral project component is the raw water pump station approximately half-way between WTP-4 and Lake Travis.

Construction of the 26-ft diameter 425-ft deep pump station shaft and pump galleries required a massive excavation into the limestone bedrock at a previously undeveloped parcel. This excavation also facilitated a portal for the new tunnel that conveys raw water from the pump station to WTP-4. Project components included:

• Raw water intake in Lake Travis, consisting of one deep-water lake tap connected to a 9-ft diameter steel intake pipe, with separate inlet screens at three elevations
• 4,386-ft of 9-ft diameter tunnel lined with unreinforced cast-in-place concrete to convey raw water by gravity from the lake intake to the pump station.
• A 26-ft diameter 425-ft deep shaft at the raw water pump station
• 3,872-ft of 7-ft diameter raw water conveyance tunnel lined with welded steel pipe from the pump station to WTP-4.

Brierley Associates provided services ranging from conceptual design through construction for the underground elements and the expansive excavation in rock for the pump station and tunnel portal