If Buddy Holly helped put Lubbock on the map, heavy rains and flooding have done their best to take it off. So, when a warning like the one quoted below is published, this major city located in the Texas panhandle takes it very seriously.National Weather Service: Lubbock, TX6:03 a.m. CDT, Thursday, June 26, 2003The National Weather Service has issued an urban and small stream flood advisory for … Lubbock County in Northwest Texas until 8:00 a.m. CDT.Excessive runoff from this storm will cause flash flooding of small creeks and streams … highways and underpasses. Street flooding will be widespread. In an extremely flat area that was a lakebed some 150 million years ago, heavy rains have long plagued the city of Lubbock. To relieve some of the flooding, the community developed the South Central Drainage System Project. The engineering firm of Parkhill Smith & Cooper Inc. (PSC) of Lubbock designed the system, which is expected to decrease the volume and duration of city street flooding. The storm sewer directs overflow from the playa lake system on the south side of Lubbock to a discharge point near the city’s water reclamation plant.
Workers used a rail system to haul out excavated dirt in Lubbock, TX. The original specifications included HOBAS pipe and standard reinforced concrete pipe (RCP) for both the direct-bury and tunnel portions of the project and solid-wall and profile-wall polyethylene, as well as corrugated metal pipe alternates for the direct-bury portions. When the bids were tallied, the alternative materials did not represent substantial cost savings on the project, and HOBAS was selected. General contractor Barnard Construction Company Inc. of Bozeman, MT, had used HOBAS centrifugally cast, fiberglass-reinforced, polymer mortar (CCFRPM) pipe previously on a sliplining rehabilitation project along Sloan Lane in Las Vegas, NV. The installation subcontractor, Southland Contracting Inc. of Fort Worth, TX, has more than 10 years of history using HOBAS pipes in many types of installations, including microtunneling. Consequently, the firms were confident that the pipe would perform.As an installer, Dave Taylor of Southland Contracting says he prefers the CCFRPM pipe because of its versatility and ease of installation. “We installed the pipe sections around three big tunneled curves and directly under the railroad. We also quickly repaired a piece of pipe that was damaged on-site. When it was finished, you couldn’t even tell it was repaired,” he adds. “The installation was just beautiful,” Taylor says. “We could do things with HOBAS that we couldn’t have done with other products.”The construction began in July 2001 and finished nine months ahead of schedule. Projections called for the $36 million system to be finished in April 2004. In late June 2003, the first inlets opened and the new storm sewer became functional. Additional inlets opened later, and now the entire system is operational. The project included more than 10,000 feet of CCFRPM pipes ranging from 24- to 72-inch-diameter at depths of more than 50 feet. The majority was installed by tunneling methods, either by itself or within a primary liner.
The specifications required the pipes to meet ASTM D3262 with minimum stiffness classes of 36, 46, and 72 pounds per square inch depending on the depth of cover and the installation means. PSC inspected the pipe production and testing at the manufacturing plant in Houston, TX. Robert Torres, EIT, inspector for PSC, says the “pipe performed at or above specification levels in all cases.” Nearing the end of the project, Torres summed it up, saying, “With the system now operational, all we need now is some rain to see how well it will work.”
