Things are indeed bigger in Texas. And Houston’s Northeast Transmis - sion Line is no exception. After a decade of astonishing 21.6 percent population growth, the Houston region is expected to double its cur - rent population by 2050. To keep up with projected water demands, and in response to the Harris-Galveston Subsidence District mandate to reduce groundwater pumping along the Texas coastal region, the City of Houston partnered with regional water authorities to build the Northeast Transmission Line (NETL). The NETL program, Houston’s largest water transmission program yet, is full steam ahead. The project will convey 365 MGD of treated surface water from the newly expanded Northeast Water Purification Plant (NEWPP) through 16.5 miles of primarily 108-inch steel water line from Lake Houston to west of IH-45 with various take-points and interconnections along the way. The water line will also provide redundancy for areas serviced by the existing 66-inch waterline along the Greens Road corridor. “Houston PublicWorks is integratingmultiple segments into one massive pipeline. Once complete, the City will be able to increase surface water usage to help minimize subsidence and flooding,” said Panduranga P.K. Kuruva, P.E., managing engineer for Houston’s surface water program. “Increasing water capacity is vital to meet Houston’s growing demand.” By the Numbers Houston Public Works divided the 16.5 miles into 13 construction contracts. With most of the line being 108-inch diameter, the proj - ects also included 120-inch, 96-inch, 84-inch, 66-inch, 54-inch and 42-inch diameter interconnections. All 16.5 miles of steel water line was manufactured in Texas factories with more than 21,700 metric tons of domestically sourced steel coil. The total construction cost is nearly $450 million, with 26 large diameter isolation valves, more than 17,000 linear feet of tunnels, and over 100 easement parcels. Once the Northeast Water Purification Plant (NEWPP) Expansion is completed, the NETL will serve more than 900,000 homes in Harris County. “A project of this magnitude required years of planning and extensive collaboration,” said Mackrena Ramos, P.E., vice president at Lock - wood, Andrews & Newnam, Inc. (LAN), a national planning, engi - neering and program management firm that is serving as the technical advisor. “Just the sheer size of the project makes it unique, but the number of individuals it took to make it a reality is quite amazing. From the City team to their partners, engineers, utility coordinators, manufacturers, and contractors’ workforce, we all had a vested interest to meet the water needs of Texans.” Texas-Sized Challenges For a project of this scale, challenges of equal magnitude were faced throughout the design and construction process. A Texas-Sized Endeavor Houston Public Works’ Northeast Transmission Line Takes Shape By Christine Kirby and Kevin Tran
The 13 segments were organized in three phases, known as the east - ern projects, the western projects, and the “workaround solution”. The workaround solution – three projects which fell in the middle of the alignment – was designed and built first as it could be placed in service with interconnections to the existing system on each end. This created a long bypass for a segment of the existing 66-inch water transmission main along the Greens Road corridor. The first of the projects began construction on summer 2018, and the workaround solution was placed in service by fall 2020. The City was able to isolate part of the existing 66-inch main for condition assessment and rehabilitation, all while the eastern and western segments were still in construction. By the spring of 2021, a much-needed repair was successfully completed on the existing 66-inch water line, which is a major source of water for the City and surrounding areas, including George Bush Intercontinental Airport. “The internal repair of the existing 66-inch main was crucial to restor - ing service to an essential line within the NEWPP service area. The interconnection between the 108-inch and 66-inch was on the critical path during design and construction. Now complete, the interconnect and repair provide operational flexibility and longevity to the two sys - tems,” said Ramos. Part of the workaround solution included a 1,163-foot tunnel under IH-69 at Aldine Bender Road. The freeway consists of 15 elevated
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csengineermag.com
DECEMBER 2021
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