Benefits of a Phased Approach to Force Main Assessment

Benefits of a Phased Approach to Force Main Assessment


Amy Bley, RJN Group Inc, Baltimore, MD USA
Catherine Morley, RJN Group Inc

Abstract: Force main inspections are inherently expensive. Utilizing a two-phased approach focusing on a force main’s likelihood of failure and consequences of that failure allows the owner to concentrate inspection efforts and resources where most needed.

The first phase evaluation is used to establish a baseline comparison of the force mains within a system. This typically includes record drawings study, historical break data, institutional knowledge, and operational conditions. Inspecting accessible assets such as transition manholes and air release valves can provide valuable information about the force main’s condition. The goal of this first phase is to identify specific stressors that each force main is subject to and use that information to identify what additional testing can and should be done to determine its condition.

The second phase of inspections are more specialized and expensive to conduct and should be performed on those force mains considered to have a high consequence of failure or a high likelihood of failure. Secondary phase inspections can include: cathodic protection system evaluation, acoustic leak detection, broadband electromagnetic inspection, CCTV, soil testing, and electromagnetic inspection to determine wire breaks in prestressed concrete pipe.

This paper will explain the benefits of a phased approach in determining force main conditions, different inspection technologies available, and using specific case studies will show how trenchless and traditional open cut techniques can be used together to save time, effort, and money.

Publication Date: 2019

Presented at:
NASTT’s 2019 No-Dig Show Chicago, Illinois
March 17-21, 2019 | Paper Number: MM-T3-05

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