The former dry cleaners operated in a strip mall unit from approximately 1990 to 2017. EEC Environmental (EEC) was approached by the client to provide a quote to complete confirmatory soil vapor sampling and continued soil vapor extraction (SVE). An SVE system had operated at the site for the previous 5 years. EEC performed the initial soil vapor sampling and detected elevated chlorinated hydrocarbons in existing soil vapor probes in the rear of the strip mall unit near the former location of the dry cleaning machine.
EEC research of the prior site data indicated soils at the site were very tight and stiff silts and clays continued rebound of chlorinated hydrocarbon concentrations during previous system pulsing and elevated chlorinated hydrocarbon concentrations limited to the upper 10 feet of soil. EEC provided the client a quote to continue SVE operations but also an optional scope and cost to excavate the affected soil. The cost-benefit analysis determined the cost to run SVE exceeded the estimate to perform the excavation within one year.
EEC projected SVE operations would require at least another three years to complete the remediation. The client selected the excavation option and the onsite work was completed within 2 weeks following receipt of the Southern California permits. The project scope of work included meetings with the Southern California County Fire Department, completing a Remedial Action Plan (RAP), obtaining RAP approval from the lead agency, prepare unit for the remediation including lock-out and tag-out of utilities, concrete slab removal and soil excavation with a mini-excavator, collection and laboratory analysis of soil confirmation samples, restore utilities, slurry backfill of the excavation, concrete slab replacement, and secure the tenant unit.
In addition, EEC installed three horizontal vapor wells in the base of the completed excavation to collect conformation soil vapor samples and potentially use to perform polishing SVE. Well heads extended outside the rear of the tenant unit so sampling or SVE could be performed without disturbing a future tenant. Soil and soil vapor laboratory results indicated concentrations below residential standards and EEC anticipates receiving unrestricted closure for the site from the Southern California County Fire Department.