C+S August 2020 Vol. 6 Issue 8

The Interstate 35 corridor, between San Antonio and Austin, is one of the fastest growing regions in the United States. According to projec- tions from the Texas Water Development Board, the corridor popula- tion is expected to grow from 4.27 million in 2014 to 5.71 million in 2030— a 34 percent increase. To meet the long term water needs resulting from this growth, the Al- liance Regional Water Authority (Alliance Water), formerly the Hays Caldwell Public Utility Agency (HCPUA), has been working on a massive water supply project. The $450 million project, which will be completed in 2023, will deliver 22,000 acre-feet of treated drinking water per year, enough to serve several communities in the corridor until 2040. Planning and Partnerships The project’s planning began 17 years ago when the Hays County cit- ies of San Marcos, Kyle, Buda and the Canyon Regional Water Author- ity, which supplies water to portions of central and south Texas, banded together. “All the nearest water sources were fully allocated, and the area continued to grow very rapidly,” said Graham Moore, P.E., Alliance Water’s Executive Director. “The utilities dealt with this by instituting stringent water conservation measures while simultaneously investing in a future water supply.” A feasibility study, performed by Lockwood, Andrews & Newnam, Inc. (LAN), a national planning, engineering and program manage- ment firm, identified the Carrizo-Wilcox Aquifer in eastern Caldwell County as the nearest groundwater source that will be able to deliver a large volume of high-quality water year-round to all the participants. For the next nine years, Alliance Water negotiated water leases with landowners and obtained permits from conservation districts to pump the groundwater from the aquifer. This was followed by a multi-year planning process to determine the infrastructure needed to produce, treat and deliver water to all the participants. During the planning phase, Alliance Water decided to split up the proj- ect into two subphases – Phase 1A and Phase 1B. Phase 1A, which is much smaller than Phase 1B, consists of two segments of 24-inch diameter pipeline totaling five miles and a booster pump station to con- nect the water systems of Kyle and Buda. “The City of Buda needed water sooner than anybody else,” said Moore. “They are also our smallest participant. We worked out a sys- tem where the cities of Kyle and San Marcos can share their excess water to meet Buda’s needs until the long-term Carrizo-Wilcox water becomes available.” Rapid Growth Spurs Massive Water Project By Travis Michel, P.E.

Aerial view of 24-inch pipe installation

Phase 1A Booster Pump Station

Phase 1B The bigger and more significant piece of this program is Phase 1B. This phase includes the design and construction of a new 22,000 acre- feet per year pump station, a 19.5 MGD treatment plant, a well field with 11 stainless steel wells, two miles of raw water lines, 95 miles of treated water pipelines ranging in diameter from 24 to 42 inches that will be built in five segments, an administration, operations and maintenance facility, and connection points to all the stakeholders. In 2018, as Phase 1B began, the Guadalupe Blanco River Author- ity (GBRA), another regional water provider that serves the cities of Lockhart, New Braunfels and Goforth SUD, partnered with the Alli- ance Water. This agreement will double the project’s ultimate output of 15,000 acre-feet per year, allowing both organizations to save tens of millions each from cost sharing throughout the life of the system, and reduce the project’s environmental impact. “Some of GBRA’s customers were already located along our planned pipeline routes,” said Moore. “Instead of building a new pipeline, GBRA agreed to bring its raw water to our treatment plant, where we will treat and transmit by oversizing the treatment plant and transmis- sion pipelines. This collaboration has allowed us to work in tandem to improve the project’s economies of scale.”

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august 2020

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