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Technology Report Released For Force Main Rehab
The second most utilized method is sliplining, an online method in which a new pipe with a smaller diameter than the old one is inserted and either pushed into or pulled through the old pipe. Pipe sections can be pre-assembled by butt fusion or joined together one at a time as needed. PVC, DI and fiberglass reinforced plastic/glass reinforced plastic (FRP/GRP) are typically sliplined in this fashion, while HDPE is butt welded. Fusible PVC is also finding use in this application.
Another online method, pipebursting, involves using a bursting or splitting device to break up and disperse the old pipe while pulling a replacement pipe behind the device. This process can be used for diameters from four to 60 inches, utilizing high density polyethylene (HDPE), PVC or DI as replacement pipe. Sometimes upsizing the existing diameter can be accomplished by this process if needed.
The report also identifies gaps between what is needed and what is available, e.g.: the biggest need is for a fully structural liner which can be installed in a live sewer – unlikely for at least a decade; but, there are vendors currently testing and developing liners with the purpose of achieving a minimum 50 year design life.
One method of assisting owners in their efforts to apply some of these emerging technologies will be in the publication of demonstration projects and case studies. Also, setting up a decision support system to help a utility ask the right questions, so that a viable rehabilitation solution emerges, is paramount.
The decision-making process relies on data from inspection to assess risk levels and to decide on necessary actions. One of the key data elements needed is verification of the long-term performance of pressure rehabilitation systems. This should be a major objective of the retrospective and demonstration projects which are currently under way as part of another phase of this overall EPA project.
Complete report available free
The report may be downloaded at no cost from the U.S. EPA website, Risk Management Research/Publications. Click the 2010-2008 tab at http://www.epa.gov/ORD/NRMRL/publications.html, or go to http://www.epa.gov/nrmrl/pubs/600r10078/600r10078.pdf to go directly to the publication.