Pre-Chlorinated Pipe Bursting Offers Effect Water Main Rehab Option

6th In A Series From The IPBA
By by Matt Timberlake President, Ted Berry, Trenchless Technologies Team LLC, International Pipe Bursting Association Marketing Committee and Andy Meyer, President, Murphy Pipeline Contractors Inc., International Pipe Bursting Association | October 2011, Vol. 66 No. 10

The construction starts by pre-fusing a continuous HDPE or PVC pipe above ground and following standard test procedures. A mechanical cap is installed on one end of the pipe and a sealed pipe burst pull head at the other end protecting the pipe from possible contamination during installation. This leaves a fully sealed pipe both during and after the testing. Pressure test, disinfection and chlorination can be performed per standards and the pipe left stored on the jobsite. All static pipe bursting will require a minimum of two pits to be excavated: a pipe insertion pit and a machine receiving pit. Once the pits are excavated, the pipe exposed and proper trench safety measures followed, the water main is ready to be isolated, drained and cut out. This is the timeframe in which service to effected homes, businesses and industry will be without water service. The static pipe burst machine is now set into the receiving pit and high tonnage rods pushed through the existing pipeline. These rods are specially designed to be able to be pushed through heavily tuberculated pipes which eliminates any need for cleaning of the existing pipe. Once the rod reaches the pipe insertion pit, which is typically located 300-500 feet away, tooling is attached that will split the existing pipe, expand the ground to facilitate the outside diameter of the new pipe, and simultaneously pull in the new product pipe. A tracer wire is pulled allowing utility workers the ability to locate the newly installed plastic pipe in the future. Once the new pipe is pulled through from end to end, the pipe bursting machine is removed and mechanical connections used to connect the new pipe to the existing water pipe which is then followed by restoration of service.

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The time traditionally required to isolate, install and reconnect a water main from two to 12-inches in diameter is approximately six to 8 hours depending on length and site specific challenges. Pipes larger than 12-inches take approximately 50 percent longer due to the additional work involved with handling pipe and the size of connections.

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