Environmental Effects of Cured-in-Place Pipe (CIPP) Repairs

The California Department of Transportation (Caltrans) has many drainage facilities that have deteriorated culverts. In many cases these culverts lie under busy, multi-lane highways and some under deep fills. Open trench replacement of these culverts is expensive and causes significant impacts on the traveling public using the highways above. Industry has developed numerous trenchless methods to rehabilitate these culverts without digging up the highway. One trenchless method is to use Cured in Place Pipe (CIPP) inside of the existing failing culverts. However the environmental impacts of this method have been questioned by the Regional Water Quality Control Boards (RWQCB) for potential water quality impacts from the residual concentrations of styrene from the resin used in the CIPP. The San Francisco and North Coast RWQCB have required Caltrans to develop specs for flushing and testing the CIPP repair methodology until results show acceptable levels of any target constituents including styrene monomer or other appropriate monomer and any toxic additives. This study will investigate the discharge concentration and test additional procedures that may be adopted by Caltrans to decrease the time after installation that is required to meet regulatory requirements.