| The predicament: A pipeline in need of rehabilitation in Tulsa, Oklahoma, ran under a residential carport. Furthermore, it was found that digging a trench to put in a new section of pipe not only would have required removal of the carport but also half of the roof on the adjoining house.
The solution: The City of Tulsa turned to AMERICAN GS Push Pipe for the first time in a 150-foot trenchless replacement installation. The results were so good that the city used another 500 feet of AMERICAN GS Push Pipe a few months later in a trenchless replacement for an emergency repair. Last year, Tulsa ran into another situation in which a trenchless replacement was a viable option: a pipeline rehabilitation project that included deep street crossings and neighborhoods with extremely tight installation areas. With two successful GS Push Pipe projects under its belt, Tulsa decided to bid trenchless replacement along with the conventional remove-and-replace trench method, letting the contractor make the final decision for each line segment. "There are times when trenchless is the way to go," said Terry Roller, vice president/estimator for Tulsa-based Ram Engineering and Construction, Inc., contractor for the job. "This was one of those times." The project, the Douglas Creek Pipeline Rehabilitation No. 2, called for 2,860 feet of AMERICAN 10-inch GS Push Pipe to replace existing 8-inch clay pipe. GS Push Pipe is bell-less ductile iron pipe with a uniform outside diameter across the gasketed joint. The joint provides an efficient transfer of jacking loads from one pipe section to the next while providing a positive seal for gravity or low head applications up to 100 feet (43 psi). "We had some concerns about using polyethylene pipe," said Robert Shelton, Tulsa’s acting lead engineer for Wastewater Design. "We had seen the pipe from AMERICAN, and liked the way it looked. We felt like we were putting a longer-lasting piece of pipe in the ground. With polyethylene pipe, we were concerned about it being scarred by the clay pipe fragments. But we just didn’t have that concern with the iron pipe." The installation process, although relatively new and "iffy," was actually pretty simple. "We took a jacking machine and put the right-size head on it for the size of pipe we’re using," Roller said. "In this case, we had a head for the 10-inch GS Push Pipe we were installing, so when we ran the head into the old 8-inch pipe, it would burst and expand the hole for the new pipe. We dug a pit right outside the manhole, set the machine up, forced the head into the existing pipe until it began to burst and then just forged ahead." "The 8-inch line we replaced was running at capacity and had to be pumped all the time," Roller said. "We were in deeper jacking pits than usual on several of the segments. The existing clay pipe was on a concrete cradle, and we got hung up on the cradle a couple of times. But, other than that, it was a pretty simple process. AMERICAN’s pipe itself is a good product. There are a lot of safety factors built in. "Begun in November 1998 and finished early this year, the Douglas Creek project was the third and largest trenchless project in Tulsa where AMERICAN GS Push Pipe has been used. "This is the first really significant project we’ve used this method on, and we’re real pleased with the results," Shelton said. "We’ll feel good about it if we need to use it again. We like the pipe, and we’re familiar with AMERICAN from using their pipe on other construction projects." "We’re dealing with a new product and new technology, so there’s going to be a learning curve," Roller said. "We’re pleased and a little surprised the learning curve for us has been short. But we’ve got some good heads in our organization and people in the field who can make things work. "The research and technical people at AMERICAN have provided us with a lot of support. And we got the pipe faster than we expected. It’s not a mass-produced product, but we got it in about four weeks. We’ve done business with AMERICAN for a long time, and they’re the kind of people you like to deal with."
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A segment of AMERICAN 10-inch GS Push Pipe is shown shortly before being pushed into place. Remnants of the broken 8-inch clay pipe being replaced can be seen at the outer edge of the hole.
This close-up shot shows the head on the end of the AMERICAN GS Push Pipe. Workers jacked the head into the existing 8-inch clay pipe, bursting it by applying direct pushing pressure to the GS Push Pipe.
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| Owner: | City of Tulsa, Oklahoma |
| Project: | Douglas Creek Pipeline Rehabilitation No. 2 |
| Engineer: | Consoer Townsend Envirodyne Engineers, Inc., Tulsa, Oklahoma |
| Contractor: | Ram Engineering & Construction, Inc., Tulsa, Oklahoma |
| Material: | 2,860 feet of AMERICAN 10-Inch GS Push Pipe |
| Sales Engineer: | Michael Tucker |
| Customer Service Representative: | Kelly Diehl |
© 1999 American Cast Iron Pipe Co.
