Burlingame Dry Cleaner

Chlorinated solvents were discovered beneath a San Francisco Bay Area dry cleaner during a Phase II investigation that was instigated as part of financing the property. We used shaft excavation to remove soil with high concentrations of tetrachloroethylene (PCE) from the interior of the dry cleaners building. An area approximately 20 feet by 20 feet was drilled down to 25 feet below grade using an excavator-mounted 24-inch diameter low-mast drill capable of drilling to a depth of 50 feet. The bore locations were staggered so that no two adjacent locations were drilled consecutively. Bores were back filled with a sand slurry control density fill and allowed to set-up over night. Areas surrounding the previously drilled and backfilled bores were then drilled out until the entire footprint had been removed. Over one hundred slightly overlapping bores were drilled and back filled within a week. Excavated soil was carted outside the building through an opening created for the work and placed into 20 cubic yard roll-off bins. The soil was disposed as RCRA hazardous waste; soil with extremely high concentrations required out-of-state treatment. Diesel equipment was outfitted with scrubber technology to minimize exhaust hazards and an extensive ventilation system was used to generate adequate fresh air exchange. This methodology allowed for deep indoor excavation of source material without the need for shoring.