WHO: City of Brownwood, Texas
SERVES: 20,000 customers
PROJECT: In-house replacement of clay with restrained-joint polyvinyl chloride (PVC) pipe
MACHINE: TT Technologies' Grundoburst 800G
COST: $20/foot ($94,000) versus $40-80/foot ($188,000 to $376,000) for contractors
THE LATEST: Although $275,000 in equipment and materials cost more than open-cutting, this department's investment in a static pipe-bursting machine. And employee training is paying off in faster construction and lower labor costs.
For four years, Brownwood, Texas, Director of Utilities David Harris has led his 10-person Wastewater Collection Department in replacing 20,000 feet of 6- to 8-inch clay sewer pipe with CertainTeed Corp.'s 8-inch Certaflow Greenline PVC pipe.
Harris chose static over the more popular pneumatic pipe-bursting because it's compatible with any pipe that can be fused or locked together mechanically; and restrained-joint PVC for its flow performance. Where the clay pipes flowed at 50% to 75% capacity during peak times, the larger pipes reach only one-third of their capacity, leaving plenty of room to accommodate heavier loads in the future.
He estimates static-bursting takes one-third the time of open-cut replacement. His crew can replace 330 feet of pipe – with video inspection, re-setting 10 taps, replacing manholes, and cleaning up – in less than five days, which adds up to nearly 1 mile every year. They've knocked off about 4 miles toward his goal of replacing 50 of the city's 150 miles of clay pipe. In another year, the machine will have paid for itself and they'll be using it virtually for free (so far the only maintenance expense has been to replace a hydraulic fitting).
His decision to improve the pipeline network one hot spot at a time has resulted in 60 separate installations. “Our approach has been to replace the mains that cause the most overflows and call-outs first, so our work has been scattered all over,” Harris says.
Aside from making customers happy, this strategy keeps emergency calls and costs down. Harris cut $5,000 from his overtime budget this year.
The department's also more proactive. Each month, several sections of clay pipe is cleaned out by hydrojet to avert overflows. But once the crew replaces a section, it's removed from the maintenance list forever. “Instead of cleaning pipes, we're able to focus on replacing them,” he says.
Static-bursting allows the crew to tackle projects they might not have otherwise undertaken. One 1,375-foot section ran beneath two railroad spurs, 40 feet of concrete road, two natural gas lines, two water mains, three commercial driveways, and a farm-to-market road. The nation's first installation of 12-inch Certaflow Greenline PVC – which Harris specifically requested for the job – was completed in six days despite requiring four burst sites because of bends in the pipeline.
Pre-planning and preparation are critical to making the installations “run like clockwork,” Harris says. Crews video-inspect before replacing a line to find each customer's tap and ensure the main is clear enough to pull the new pipe through. They also watch the weather closely, because once they start they can't stop until they finish the job.
“All it takes to make pipe-bursting work is good people, good equipment, good materials, and a desire to serve your community,” says Harris.
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