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ENVIRONMENTAL HEALTH DEPARTMENT SAN JOAQUIN COUNTY Unit p �.._�•.oG .Su ervisors Donna K.Heran,R.E.H.S. 304 East Weber Avenue, ThirdFloor Car!Borgman,R.E.H.S. as < Director Mike Huggins,R.E.H.S.,R.D.I. Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. • �.• `p • Program Manager Telephone: (209) 46$-3420 Margaret Lagorio,R.E.H.S. Qti oRa Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S, Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. LORI SHIELDS IRAN 2 7 2003 DIESEL PERFORMANCE 2804 EAST FREMONT STREET STOCKTON CA 95205 RE: Diesel Performance SITE CODE: 1120 2804 E. Fremont Street Stockton CA 95205 San Joaquin County Environmental Health Department (SJCIEHD) has reviewed the "Remedial Investigation/Feasibility Study" report dated November 19, 2002 that was submitted on your behalf by ATC Associates, Inc. (ATC) and has the following comments. The report documents site fieldwork that took place in December 2001, when three vapor extraction wells (VEW-1, VEW-2, VEW-3), three additional shallow monitoring wells (MW-5, MW-6, MW-7) and one cone penetrometer test boring (CPT-1) were installed on site, and short- and long-term soil vapor extraction (SVE) pilot tests were conducted. The monitoring wells were installed to help define the lateral extent of the shallow contaminant plume, which is present at the highest concentrations in MW-1 and MW-2. The CPT boring was advanced to investigate the vertical extent of the plume. The CPT boring was advanced and logged to approximately 72 feet below surface grade (bsg), where it hit refusal. Following this, a second direct push boring was advanced directly to 100 feet bsg and a grab water sample was collected from a conventional hydropunch tool. However, due to the failure of the CPT cone to penetrate below 72 feet bsg, the lithology at the depth of the water sample is unknown. The new monitoring wells were sampled at the fourth quarter 2001 monitoring event. Analytical results from the new wells were non-detect for all constituents analyzed. Results from monitoring wells MW-1 thru MW-4 were consistent with historical trends in showing reportable concentrations of petroleum hydrocarbon contamination in MW-1 and MW-2. The water sample collected at 900 feet bsg during the CPT investigation was non-detect for all constituents analyzed. The long term SVE test was run for 4 hours, the short term test was run for 2 hours. Results reported from the tests indicate that soil vapor extraction would be a viable remedial alternative for this site. A radius of influence of approximately 30 feet was calculated, and during the combined testing, approximately 2.64 pounds of hydrocarbons were removed from the subsurface.