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ENVIRONItIENTAL HEALTH ftEPARTMENT <br />Donna K. Heran, R.E.H.S. <br />Director <br />Laurie A. Cotulla, R.E.H.S. <br />Assistant Director <br />SAN JOAQUIN COUNTY <br />304 East Weber Avenue, Third Floor <br />Stockton, California 95202-2708 <br />Telephone: (209) 468-3420 <br />Fax: (209) 464-0138 <br />Website: www.sjgov.orgiehd/ <br />Program Coordinators <br />Carl Borgman, R.E.H.S. <br />Mike Huggins, R.E.H.S., R.D.I. <br />Margaret Lagorio, R.E.H.S. <br />Robert McClellon, R.E.H.S. <br />Jeff Carruesco, R.E.H.S. <br />Kasey Foley, R.E.H.S. <br />GURPAL S SIDHU <br />5410 STAPLES WAY <br />LINDEN CA 95236-9556 <br />RE: Waterloo Food & Fuel <br />3032 E. Waterloo Rd <br />Stockton, CA 95205 <br />NOV 3 0 2006 <br />SITE CODE: 1758 <br />The San Joaquin County Environmental Health Department (EHD) has received and <br />reviewed Remediation Report — First and Second Quarters 2006 (the remediation report) <br />and Quarterly Report — First and Second Quarters 2006 (quarterly report) as submitted on <br />your behalf by your consultant Advanced GeoEnvironmental, Inc. (AGE). <br />The remediation report indicates that during the first and second quarters of 2006, the <br />groundwater extraction (GWE) system operating on your site had removed approximately <br />1,195 pounds of total petroleum hydrocarbons quantified as gasoline (TPH-g), 119 pounds <br />of benzene and 308 pounds of methyl tert-butyl ether (MTBE). Since the GWE operation <br />began in May 2003, a total of 7,700 pounds of TPH-g, 382 pounds benzene, and 800 <br />pounds MTBE have been removed from impacted groundwater underlying your site. <br />Review of the quarterly report shows that, with the exception of the very last monitoring <br />event, contaminant concentrations in most wells in the source area show little effect from the <br />GWE operation, and locally appear to be increasing. The EHD does not view the reduction <br />of contaminant concentrations in a few wells during one monitoring event to necessarily <br />indicate a declining concentration trend. <br />At this time, your site has three groundwater monitoring wells (MW-5, MW-6 and MW-7; <br />MW-8 has been destroyed) screened in five depth intervals that AGE has defined as flow <br />units. Over recent quarters, the EHD has noted that within each of the three monitoring <br />wells, there has been a consistent downward vertical gradient between the five depth <br />intervals. Recently, contaminant concentrations in the deeper screened intervals of each well <br />(i.e. MW-5C, 5D and 5E) have similar concentrations that vary from quarter to quarter in a <br />similar pattern. The EHD is concerned that the data may be indicating cross contamination <br />between the deeper intervals within each well. It seems unlikely that the plume would have a <br />near uniform vertical concentration profile and that each screened interval within each well <br />would change over time in the same way, especially if the screened intervals are separated <br />by intervals of lower permeability. To verify the results obtained to date, EHD believes that a <br />single-screen well completed in the 175 to 185-foot interval in the core area of the plume <br />should demonstrate whether the interval is impacted or not, or if further investigation for <br />vertical extent of the dissolved plume is warranted. <br />Review of the groundwater analytical results for the monitoring well samples show that <br />impacted groundwater in the shallow screened interval, 45 to 65 feet below surface grade