No-Dig Manhole Rehabilitation Knowledge Gaps

In the USA alone, the number of manholes is estimated to be from 12 to 20 million. According to the Trenchless Technology Magazine (2010), 20% of the manholes are at least 50 years old and another 25% are 30 to 50 years old. Additionally, more than three million are believed to be suffering from serious structural decay and are in need of immediate rehabilitation or replacement. To date, there have been a number of research studies on pipeline rehabilitation; therefore, there is a wealth of experience and tools for engineers to evaluate their options while selecting the material and technology to rehabilitate sanitary sewer pipes. Manholes, on the other hand, although a vital part of sanitary sewer systems, are often overlooked. There are very limited studies, but numerous options to rehabilitate manholes. This paper discusses manhole rehabilitation knowledge gaps based on a USEPA/Water Environment Research Foundation (WERF)-sponsored project. Particular emphasis will be given to the structural capabilities of no-dig manhole rehabilitation materials and methods.