Rehabilitation Of Tce Contaminated Underground Storm Water System Using Trenchless Technology

The Naval Air Warfare Center (NAWC) at Trenton, NJ is a gas turbine engine testing facility. Trichloroethene (TCE) is used as a heat exchange medium during engine testing. As part of an on- going environmental investigation program, TCE was found in groundwater and in water discharging from the outfalls of the facility's storm water collection system. Because of high groundwater levels, it was unclear whether the TCE in the outfall discharge was entering the storm sewers via pipe connections and/or from impacted groundwater infiltrating deteriorated sewer lines. The main storm sewer lines associated with two of the facility's four outfalls, i.e., in the areas of highest TCE concentrations in groundwater, were video inspected. Structural deficiencies ranging from cracked pipe and failed joints to total collapse were found. The rehabilitation of these lines was deemed to be an important part of the facility's remediation plans. Due to the disadvantages associated with conventional pipe excavation and replacement techniques at this site, in-situ rehabilitation alternatives were considered. Cured-in-place pipe (CIPP) technology was selected as the best alternative. This technology involves the formation of a new CIPP inside an existing pipe using a novel inversion" process. The disadvantages of excavating contaminated soil to repair the deteriorated storm sewer lines were avoided. Approximately 1,900 lineal feet of pipe, ranging from 8 inches to 27 inches in diameter, were repaired using the CIPP method. A reduction in the infiltration of groundwater into the storm sewer system, and a corresponding reduction in the TCE at the outfall, was observed as a result of the repair work.