Laserfiche WebLink
RTMENT <br /> HEALTH DEpA <br /> ENVIRONMENTAL COUNTY <br /> pdV•�N.. SAN JOAQUIN COU Unit Supervisors <br /> Y. Carl Borgman,R.E.H.S. <br /> Donna K.Heran,R.E.H.S• 304 East Weber Avenue,Third Floor Mike Huggins,R.E.H.S.,R.D.I. <br /> Director <br /> R.E.H.S. Stockton, California 95202-270 Douglas W.Wilson,R.E.H.S. <br /> Al Olsen,ram Manager Mar aret Lagorio,R.E.H.S. <br /> Pro <br /> g g Telephone: (209) 468-3420 g <br /> • C'9� FORS` Laurie A.Cotulla,R.E.H.S. RobertMcClellon,R.E.H.S. <br /> / Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. <br /> Program Manager <br /> FRANK MORITA SEP 3 2002 <br /> 6622 BELMONT PL <br /> STOCKTON CA 95207 <br /> RE: Morita Brothers Site Code: 1061 <br /> 814 E Charter Way <br /> Stockton, CA <br /> San Joaquin County Environmental Health Department (EHD) has reviewed Additional <br /> Site Characterization Work Plan (work plan) dated 27 June 2002, prepared by <br /> Geological Technics Inc. (GTI) on your behalf. EHD has also reviewed: a) data obtained <br /> from nearby sites at 701 and 749 E. Charter Way to compare site geological <br /> characteristics with the subject site, b) maps depicting historical depths to ground water <br /> for the area, and c) EHD records regarding underground storage tank (UST) use at the <br /> subject site EHD comments as follows: <br /> USTs were utilized on the site from as early as 1959 to 1991. The depth to ground water <br /> in the subject site area in 1978-1979 varied from approximately 65 to 70 feet bsg, <br /> compared to approximately 39 feet bsg in 1992 and as little as 15.6 feet bsg in 2000. <br /> The period of UST use on the site includes the time of the suspected greatest depth to <br /> ground water. <br /> As noted in the work plan, EHD agreed by letter dated 24 April 2002 that the lateral and <br /> vertical extent of soil contamination and the vertical extent of impacted groundwater <br /> appeared to have been defined. However, during this review, it was noted that the lateral <br /> extent of impacted soil west of TH-4 and the vertical extent of impacted soil underlying <br /> TH-4 has not been delineated. Impacted soil extends to depths as great as 45 feet below <br /> surface grade (bsg) with concentrations of total petroleum hydrocarbons quantified as <br /> gasoline (TPH-g) and benzene as high as 5.85 milligrams per kilogram (mg/kg) and <br /> 1,000 micrograms per kilogram (µg/kg), respectively. The contaminant concentrations in <br /> soil were commonly highest at depths of 30 and 35 feet bsg, which is near the depth of <br /> the ground water table reported in 1992, so the elevated contaminant concentrations <br /> near that interval may be the smear zone of the impacted ground water at that time. <br /> Based on the laboratory results f rom soil samples collected f rom T H-1, TH-5, f urther <br /> assessment of the TH-4 area may not be necessary unless significant impacted ground <br /> water is encountered at depth in new wells installed in the down gradient direction in the <br /> TH-4 area. <br /> EHD has reviewed boring logs for the site and the nearby sites of interest and noted that <br /> on the subject site, soil between 5 feet and 25 feet bsg was commonly described as silty <br />