Project Summary

A historical release of petroleum from one or more pipelines within an underground pipeline transmission network led to soil and groundwater contamination below a busy intersection in Norwalk, California, adjacent to the I-5 Freeway in southeast Los Angeles County. Murex was hired to determine the location of the source, assess the vertical and lateral extent of soil and groundwater impacts, and to determine the specific type of refined petroleum product so as to narrow the owner of the leaking pipeline. Complicating the work was the presence of a petroleum service station near the intersection that was being studied.

A large grid of passive soil vapor testing was used to pinpoint the leak location, and a network of groundwater monitoring wells was installed to characterize the shallow aquifer. Free product samples from various wells were subjected to forensic testing to determine their unique mixture of refined and semi-refined products, in order to a) distinguish the pipeline release from the nearby gas station release, b) identify the leaking pipeline, and in turn, c) identify the pipeline owner responsible for cleanup.