Storm Sewer Rehab Utilizing Trenchless Technologies

Faced with EPA administrative orders and consent decrees, several South Florida municipalities initiated extensive sewer system rehabilitation programs in the early 1990's. Given the availability of numerous and varied repair technologies, including trenchless, the challenge faced by engineers and municipalities was to select the appropriate rehabilitation, given a certain type of defect, it's location and the amount of infiltration/inflow (I/I), if any. The key element for overcoming this challenge was to obtain complete and accurate information on the defects in sewer mains, manholes, and service laterals, and then to cross reference each individual defect with a suitable rehabilitation technology. Since storm sewers are designed to carry inflow (rain water) and groundwater infiltration is not a major concern, unless it carries soils with it, I/I is not a problem for stormwater utilities. Storm sewers however, like any infrastructure, deteriorate with age and, structural failures occur. In addition, water flowing in (infiltration) through failed joints, cracks and holes, carry the surrounding soil and silt into the pipe, forming voids under the pavement, Without underlying support, the traffic load eventually causes the pavement to break up and collapse. Faced with sometimes costly open cut repairs, including severe social costs (traffic rerouting, temporary business closure, etc.), engineers and stormwater utility owners have looked at alternate "no-dig" repair technologies. Several trenchless technologies applied for sanitary sewer repairs can also be used for repairing storm sewers. A successful repair program relies on an intensive storm sewer system evaluation survey (SSES) to obtain all necessary data for the subsequent rehabilitation phase.