Pipe Bursting in Texas
The City of Groves, Texas, had a big problem on its hands. A 665-ft section of underground truss pipe (plastic pipe with a concrete-filled, hollow wall) was in need of replacement.
The pipe was located on an easement, with an apartment complex to the right and a subdivision to the left. Trenching for that much pipe would cause a major disruption in traffic, utilities and the peoples’ lives in the adjoining neighborhoods.
A huge amount of time and money would be dedicated to rebuilding fences and driveways that were torn up during the process.
Traditionally, the Houston area has used the pneumatic pipe bursting method for this type of project, which could create lateral cracks in the surrounding utilities due to concussions generated by the process. The aforementioned 665-ft section of truss pipe was also located only 3 ft from a water line. The project team was concerned that the pneumatic method may cause water to leak from that line two or three months after the project was complete, thus taking them back to square one with the neighborhood disruption.
The city put the project out for bid and Simco Enterprises, Groves, Texas, won. Simco considered using its Ditch Witch horizontal directional drill, but it didn’t fit that application. The recommended drill also lacked the tools necessary to accommodate different sizes of pipe in this section. Sales manager Jason Collins and his team from Ditch Witch of Houston offered to deliver and demonstrate a pipe burster to Simco, with no obligation.
The demonstration led to the Ditch Witch organization’s first sale of a PR100 pipe bursting system in the United States. The Ditch Witch PR100 pipe burster was first revealed at ICUEE in October 2009.
“We were impressed with the durability and strength of this product, along with the people supporting it,” said Mike Suire, general manager of Simco Enterprises, who has 18 years of experience in trenchless pipe installation. “Underground utility installation can and does present an abundance of adversity. The PR100 demonstrated the progress of this technology over the past two decades. By purchasing this new machine, Simco Enterprises intends to utilize its versatility and production efficiency while minimizing the disruption to the surrounding area and people.”
Like most of the pipes in the United States, this section of pipe had deteriorated over time. To find a solution for the present, the cities had to look to the past.
The story goes back to a time when cities began developing sanitary systems and building the pipes and sewer treatment plants to support them. For example, the plants were designed to treat 35 million gals of fluid per day. As the pipes deteriorated over time, they could still hold the standard amount of waste; however, after one good rain, the now-cracked pipes overflowed — due to inflow and infiltration — and the plant must now process up to 100 million gals of water and sewage. To solve the problem, the overburdened plant would open its gates and let the waste flow into bayous, rivers and lakes.
Naturally, the Environmental Protection Agency (EPA) became involved because of this highly unsanitary practice. They began fining the city each time the sewer overflowed. The city couldn’t afford to keep paying fines, and the EPA couldn’t allow the unsanitary measures taken by the plants to continue. The EPA and the city agreed on two things: The solution is in rebuilding the pipes, and the city couldn’t afford to repair all of those pipes at once.
Fast forward to the 1990s. The city submits a plan to the EPA and both parties come to an agreement about how many feet per pipe can be replaced that year. The methodology is interesting. The city sends robotic cameras to determine which sections are in the worst shape by calculating the amount of grease or debris buildup. For example, if a pipe has 8-in. lines, but only 2 in. of sewer are flowing through it due to grease or debris buildup, it would be at the top of the list for replacement. Once the list is agreed upon, the city reviews the videos taken from the robotic cameras and decides whether the replacement method in each instance will be pipe bursting or other alternative methods.
In this instance, the 665-ft section needed pipe bursting, but the project held many challenges. The first obstacle to overcome was the potential disruption to utilities, driveways and fences. The PR100’s trenchless method turns this into a non-issue. It does not affect the existing infrastructure while installing the replacement pipe.
The second obstacle was the potential damage caused by “hammering.” The PR100’s static system uses hydraulics that dramatically lessens the vibration to the ground and existing utilities, thus solving the hammering problem during the project and the potential fallout afterward.
In the past, cities in the Houston area had experienced problems with equipment not being able to burst the truss pipe or handle the job, so they had to open-cut the pipes, which caused a major disruption. On this job they had the right equipment. Out of 100 tons of pulling force that the PR100 is capable of, it never exceeded 36 tons of pulling force, and Simco was able to complete the 655-ft pull in just over two hours.
Perhaps the biggest concern was the truss’s PVC pipe material itself. It stretches. Solution: The PR100 has three different cutting edges for different-size pipes. Think of it in relation to a clock on the wall. It grips the pipe at 3:00, 9:00 and 12:00 in the front where it’s narrow, so it stretches and cuts as it pulls in the new pipe.
Everyone likes a happy ending, and the City of Groves and its residents have one. Simco Enterprises has purchased a Ditch Witch PR100 pipe bursting system and the company is very happy with its performance, reliability and the support provided from Ditch Witch of Houston.
Jeri Lamerton is public relations manager at Ditch Witch, which is headquartered in Perry, Okla.