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r • • <br /> ENVIRONMENTAL HEALTH DEPARTMENT <br /> Paa`" SAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> Donna K.Heran,R.E.H.S. Carl Borgman,R.E.H.S. <br /> Director 304 East Weber Avenue, Third FIOOI Mike Huggins,R.E.H.S.,R.D.I. <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. <br /> Program Manager Telephone: (209)468-3420 Margaret Lagorio,R.E.H.S. <br /> �i F o e`° Laurie A.Cotulla,R.E.H.S. Robert McClellan,R.E.H.S. <br /> Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. <br /> MAR 0 5 ?nn? <br /> KAREN PETRYNA <br /> EQUIVA SERVICES LLC <br /> P 0 BOX 7869 <br /> BURBANK CA 91510-7869 <br /> RE: Former Texaco Station SITE CODE: 1055 <br /> 440 Charter Way <br /> Stockton CA 95206 <br /> San Joaquin County Environmental Health Department (SJC/EHD) has reviewed the "Site <br /> Investigation Report" dated December 13, 2001 that was submitted on your behalf by <br /> Cambria Environmental Technology, Inc. (Cambria) and has the following comments. <br /> The report documents site fieldwork that took place in October 2001, when three cone <br /> penetrometer test (CPT) borings were advanced, and November 2001, when one off-site <br /> monitoring well was destroyed. Discrete soil and groundwater samples were collected <br /> adjacent to the CPT borings, at depths to 130-feet below surface grade (bsg) in CPT-5 <br /> and CPT-7, and to 80-feet bsg in CPT-6. Soil contamination was apparent at CPT-5 in <br /> the 105 and 116-feet bsg samples, and at CPT-7 in the 50, 70, 100 and 125-feet bsg <br /> samples. One soil sample was collected from CPT-6, at 10-feet bsg. It was non-detect <br /> for all constituents analyzed. Water contamination was evidenced at CPT-5 in all three <br /> samples collected, from 110 to 130-feet bsg; at CPT-6 in the 65-feet bsg sample only; and <br /> at CPT-7 in all six samples collected, from 63 to 130-feet bsg. <br /> CPT-5 was advanced on site near the northeastern dispenser island. It was located <br /> close to CPT-1, which was advanced in a prior mobilization. Four discrete groundwater <br /> samples were collected at CPT-1 from 60 to 92-feet bsg. All four contained very high <br /> concentrations of total petroleum hydrocarbons as gasoline (TPHg) and benzene. CPT-5 <br /> was advanced to collect samples from below those collected at CPT-1. While the <br /> concentrations of contaminants in the samples from CPT-5 showed some attenuation with <br /> depth, vertical definition of the plume was not made with this boring. <br /> The only recommendation contained in the report was for a file review to be completed to <br /> look for potential off-site sources of the contamination found in CPT-7, and that based on <br /> the findings of the review, Cambria will make a recommendation as to whether or not they <br /> think a Problem Assessment Report should be prepared. <br /> The findings of the collective CPT investigations indicate that a deep groundwater <br /> contaminant plume exists at this site. SJC/EHD directs that two sets of a minimum of <br /> three discretely screened monitoring wells each be installed, one set to monitor the zone <br /> with high concentrations of contaminants at about 70-feet bsg, and another to monitor the <br />