One of the main considerations when dealing with a trenchless rehab project is managing the existing flows during a liner installation. A common solution for the flow is temporary bypass pumping; a process to pump the pipeline’s flow around the section of pipe being renewed. This is often achieved through a pump and piping network, to transport the flow around the repair section. Per NASSCO’s Bypass Pumping Specification, a comprehensive bypass pumping plan often includes (but is not limited to)
• Staging areas for pumps
• Sewer plugging method and types of plugs
• Number, size, material, location and method of installation of suction piping;
• Number, size, material, method of installation and location of installation of discharge piping;
• Bypass pump sizes, capacity, number of each size to be on-site and power requirements;
• Downstream discharge plan;
• Method of protecting discharge manholes or structures from erosion and damage;
• Method of noise control for each pump and/or generator;
• Schedule for installation of and maintenance of bypass pumping lines;
• Plan indicating selection location of bypass pumping line locations.
Trenchless rehabilitation technologies that involve curing in the lining process require flow to be pumped around the area of repair. Additionally, many trenchless rehabilitation methods require bypass for larger diameter pipelines, especially those with higher flow levels. In the case of CIPP, certain smaller diameter applications will properly handle flow solely with plugs and no bypass. However, in the instances of longer runs and larger pipes, a bypass pumping operation becomes much more likely.
Temporary bypass pumping is often vital for CIPP projects; however, it is not inexpensive. We recently conducted an in-house study that is detailed in our white paper, which you can download here. We analyzed 40 CIPP bid tabulations from 25 states, dating from 2015 – 2019. Given these constraints (and others detailed in the paper), the average portion bypass pumping cost was over 15% of the total bid. This percent increased when isolating projects dealing with diameters larger than 20”. For the full results, download our paper.