Rapid Growth Spurs Massive Water Project

By Travis Michel, P.E.

The Interstate 35 corridor, between San Antonio and Austin, is one of the fastest growing regions in the United States. According to projections from the Texas Water Development Board, the corridor population 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 Alliance 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 cities of San Marcos, Kyle, Buda and the Canyon Regional Water Authority, 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 management 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 project 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 connect 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 system 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.”

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 Authority (GBRA), another regional water provider that serves the cities of Lockhart, New Braunfels and Goforth SUD, partnered with the Alliance 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 transmission pipelines. This collaboration has allowed us to work in tandem to improve the project’s economies of scale.”

Major firms involved in Phase 1B include: Kimley-Horn & Associates Inc. as program manager, LAN for easement acquisition, Blanton & Associates for environmental services, LNV Inc. for raw water system design, Walker Partners for water treatment plant design, Freese & Nichols Inc. for pump station design, and Plummer for the elevated storage tank design. The five segments of the treated water pipelines are being designed by LAN, Walker Partners, BGE, Inc., Freese & Nichols, and K Friese + Associates.

Ductile Iron pipe inspection

Project Challenges

The scale and complexity of the project has created numerous challenges. Chief among them is the coordination required between the different water entities and the various firms involved in the project. With a full-time staff of only two people, Alliance Water outsourced the project’s design and hired Kimley-Horn to manage the program and track all the moving pieces.

“From producing design standards to ensuring cohesion among the design packages, the program requires a lot of coordination,” said Moore. “We want to ensure that even the valves are of the same type, so we are not stocking a lot of spare parts for different equipment. The coordination needed for the different pipeline segments, the easement acquisition, the system hydraulics and other elements of this project has been a tremendous day-to-day challenge.”

Water quality was another challenge. To ensure the new water source could blend with the customers’ existing water supplies, Alliance Water and the project team spent considerable time in the preliminary design phase. This included gathering data on the existing water sources, determining where the participants received treated water, understanding the chemical makeup of these water supplies and then designing a treatment regime suitable for every participant.

“Our goal is to ensure that our sponsors require little, if any, additional treatment when they receive our water,” said Moore. “We worked hard to find the right mixture in our treatment techniques. We are talking about a geographical area that spans 35 miles and they all have slightly different water sources and blends. We are also planning for issues that may arise decades down the road. At the water treatment plant, we have allocated space for chemicals that we may need to add in the future.”

Cost containment is another concern. Estimating the project’s construction costs in the current environment with the prices of commodities, such as steel, fluctuating hasn’t been easy, notes Moore.

Boring under commercial driveway

“Considering that we will be using steel at the water treatment plant, elevated storage tank, booster pump station and possibly 95 miles of pipelines, it is a big component in the overall project costs,” said Moore. “We went through an eight-month process evaluating cost-saving measures that we could implement without impacting the level of service. Out of the nine measures that we have identified, we are implementing five. While we will not know the true costs until we receive bids, we are trying to hedge a little bit against what those future costs may be and finding ways to ensure we have the proper financing without over-burdening our rate payers.”

Finally, easement acquisition has been a challenge. Alliance Water and LAN are negotiating and acquiring approximately 300 easements spanning 85 miles. With individual property owners having different requirements, addressing their concerns adequately and securing these easements has been a long process. In addition to negotiating easements for the current project, Alliance Water is acquiring easements for future pipelines in these corridors.

Conclusion

Despite these challenges, the project is on schedule. The $12 million Phase 1A, which is currently under construction, will be completed at the end of this year. Phase 1B, which will cost $450 million, is scheduled for completion in June 2023. Plans are also underway for Phases 1C and 1D that will provide an additional 8,100 acre-feet of water per year in the future. These phases are expected to be completed in 2035. Thanks to Alliance Water and its partners, future generations of central Texans will have access to good, clean water for the next 50 years and beyond.


Travis Michel, P.E., is an associate and infrastructure manager at Lockwood, Andrews & Newnam, Inc. (LAN), a national planning, engineering, and program management firm. He can be reached at TMMichel@lan-inc.com.

The post Rapid Growth Spurs Massive Water Project appeared first on Civil + Structural Engineer magazine.



source https://csengineermag.com/rapid-growth-spurs-massive-water-project/

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