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ENVIRONMENTAL HEALTHT)EPARTMENT <br /> °U N <br /> Donna K. Heran, R.E.H.S. SAN JOAQUIN COUNTY <br /> Program Coordinators <br /> Director 304 East Weber Avenue,Third Floor Carl Borgman, R.E.H.S. <br /> . - Laurie A. Cotulla,R.E.H.S. Stockton,California 95202-2708 Mike Huggins, R.E.H.S., R.D.I. <br /> • O � F ORd F• Assistant DirectorTelephOrie: (209)468-3420 Margaret Lagorio,R.E.H.S. <br /> q ......-... <br /> Robert McClellon, R.E.H.S. <br /> Fax: (209) 464-0138 Jeff Carruesco, R.E.H.S. <br /> Website:www.sjgov.org/ehd/ Kasey Foley, R.E.H.S. <br /> HAROLD & DENA KNOWLES OCT 2 6 2006 <br /> C/0 LAW OFFICE OF PATRICK D RIDDLE <br /> 1811 GRAND CANAL BLVD STE 2 <br /> STOCKTON CA 95207-8107 <br /> RE: 102 S. Wilson Way Site Code: 9031 <br /> Stockton, CA <br /> San Joaquin County Environmental Health Department (EHD) has received and <br /> reviewed Third Quarter 2005 Groundwater Sampling Report (TQ05), dated 06 October <br /> 2005, prepared on your behalf by Ground Zero Analysis, Inc. (GZA) for the above <br /> referenced site. Included in TQ05 were the results of a vapor extraction test performed <br /> on the inactive soil vapor extraction (SVE) system and on individual vapor extraction <br /> wells. The test was conducted to evaluate the potential for additional remedial benefits <br /> that may result from repairing and operating the SVE system. <br /> GZA reported an estimated initial vapor recovery rate of 20 pounds of contaminant per <br /> day and recommended repair of the SVE system and re-initiation of the SVE system <br /> operation. The EHD concurs with this recommendation and directs that appropriate <br /> steps be taken to repair or up-grade the SVE system and return the system to <br /> continuous operation. Provide a schedule to the EHD by 15 November 2006 for <br /> repairing and restarting the SVE operation. If additional vapor extraction wells are <br /> believed necessary, provide the rational and work plan with the schedule. <br /> The EHD has also received and reviewed Second Quarter 2006 Groundwater Sampling <br /> Report (SQ06) dated 26 September 2006. In SQ06, GZA indicates that the site <br /> conceptual model (SCM) will be submitted in the report for the third quarter 2006 <br /> quarterly monitoring event. After receiving and reviewing your SCM and the SCMs for <br /> the nearby sites with unauthorized releases from underground storage tank (UST) <br /> systems, the EHD will attempt to assist you with deciding the appropriate wells for each <br /> responsible party to monitor. <br /> Groundwater monitoring data from monitoring well MW-17C appears to indicate that the <br /> vertical extent of impacted groundwater on site has been delineated. The lateral extent of <br /> the onsite dissolved contaminants has been generally delineated, but is complex due to <br /> the probable intrusion and/or commingling of plumes along the southern margin of the site <br /> and the more recent possible plume migration onto the western portion of the site. In <br /> addition, the width and distribution of the dissolved plume/commingled plume along the <br /> eastern margin of the site is not well characterized at this time. However, with the SCM <br /> nearly ready to be submitted, EHD believes that a corrective action plan (CAP) or <br />