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ENVIRONMENTAL HEALTH DEPARTMENT Pp U,IN SAN JOAQUIN COUNTY Unit Supervisors Donna K.Heran,R.E.H.S. Carl Bergman,R.E.H.S. a 304 East Weber Avenue, Third Floor 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. • eqp Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. 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. ERNEST P GIANNECCHINI SEP 0 22004 ERNIE' S GENERAL STORE 4407 EAST WATERLOO ROAD STOCKTON CA 95215 RE: ERNIE'S GENERAL STORE 4407 EAST WATERLOO ROAD STOCKTON CA 95215 San Joaquin County Environmental Health Department (EHD) has reviewed Quarterly Dort —FirstQuarter 2004 dated June 30,2004 prepared by Advanced GeoEnvironmental, Inc. (AGE). Concentrations of methyl tert butyl alcohol (MTBE) have significantly dropped and rose, respectively,in the groundwater samples of monitoring wells MW-1 and MW-4. Analytical results of the groundwater samples from MW-1 were non-detect August 2003, then rose to 890 micrograms per liter (ug/1) of MTBE in December 2003, and dropped to non-detect again in March 2004. In contrast, analytical results of the groundwater samples from MW-2 were first reported at 77 ug/1 of MTBE in August 2003, then dropped to non- detect in December 2003, and rose back to 1,700 ug/1 in March 2004. Similarly but to a lesser degree, analytical results of the other two wells MW-2 and MW-3 also do not appear to be consistent with their previous quarterly results. Analytical results of MW-2 samples dropped to non-detect level in MTBE in Match 2004 from 27 ug/1 the previous quarter, and MW-3 rose to 200 ug/1 in March 2004 from non-detect level the previous quarter. Depth to groundwater (DTW) was recorded at 70.94 feet below surface grade (bsg) for MW-1 in August 2003, 70.05 feet bsg in December 2003, and 67.46 feet bsg in March 2004. Groundwater flow direction was calculated to be in a northwest direction. The highest concentrations of b1TBE in the soil were collected at 15.5 bsg feet during the tank removal in January 1999 at 17 milligrams per kilograms (mg/kg). The highest concentrations of MTBE in the vadose zone according to subsequent investigation in September 2001 were 0.130 mg/kg in soil sample Bl at 40 feet bsg. MTBE was found in low concentrations (below 0.002 mg/kg) or non detect in the soil samples collected from 10, 20, 30, 40, 50, 60, and 70 feet bsg during the July 2003 investigation. There does not appear to be a significant amount or concentrations of MTBE in the soil that corresponds to the fluctuation of the reported analytical results of dissolved MTBE in groundwater. EHD is very concerned if the inconsistency of the analytical results reported for the last three quarters is real or is a result of improper sampling procedure,mis-labeling, or laboratory error. EHD requests the analytical results of the 3rd quarter sampling event conducted on August 31,2004 at the above-referenced site be submitted to EHD within 24 hours after released from the laboratory. If the sample results continued to reflect