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<br /> San Joaquin County
<br /> .C, Environmental Health Department DIRECTOR
<br /> Donna Heran, REHS
<br /> 600 East Main Street
<br /> PROGRAM COORDINATORS
<br /> { Stockton, California 95202-3029 Robert McClellon, REHS
<br /> Jeff Carruesco, REHS,RDI
<br /> �cd .. :.•a�P Website: www.sjgov.org/ehd Kasey Foley,REHS
<br /> Phone: (209) 468-3420
<br /> Fax: (,RRA) 46"1�8
<br /> Remo Canepa
<br /> Canepa's Car Wash
<br /> 1536 N Hunter
<br /> Stockton, CA 95204
<br /> Subject: Canepa's Car Wash
<br /> 248 Park Street
<br /> Stockton, CA 95202
<br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Ground
<br /> Water Monitoring Well Installation Report (Report), dated October 2, 2009 and Interim
<br /> Remediation Action Work Plan (WP), dated October 23, 2009, both prepared by your
<br /> consultant Advanced GeoEnvironmental, Inc. (AGE).
<br /> The Report discusses the findings of the site investigation conducted during the months
<br /> of August and September 2009 which involved installation of monitoring wells MW-8
<br /> though MW-17. The highest concentrations of soil contamination were found in the MW-
<br /> 10 soil samples collected at 35 and 90 feet below surface grade (bsg), which contained
<br /> 4,400 and 3,400 milligrams per kilogram mg/Kg total petroleum hydrocarbons quantified
<br /> as gasoline (TPH-g), respectively. Lower concentrations of soil contamination were
<br /> found in the MW-10 soil sample collected at 110 feet bsg at 18 mg/Kg TPH-g. Soil
<br /> samples collected from MW-8, MW-9, and MW-11 though MW-17 at depths ranging from
<br /> 10 to 110 feet bsg, contained TPH-g concentrations ranging from less than 1.0 mg/Kg to
<br /> 8.6 mg/Kg. Based on these results and historical site data, the soil plume is most
<br /> impacted at the source area at 35, 50 and possibly 90 feet bsg as shown by data from
<br /> B-2 and MW-10, with TPH-g concentrations reaching as high as 21,500 mg/Kg in B-2 at
<br /> 35 feet bsg. There is minor to no soil impact in all directions away from the source area
<br /> at depths ranging from 15 to 110 feet bsg as demonstrated by data from MW-2, MW-6,
<br /> MW-8, MW-14, and the Farmer Property monitoring well located at 610 North Hunter,
<br /> FW-5, where TPH-g concentration range from less than 1 mg/Kg to 348 mg/Kg. In the
<br /> Report, AGE concludes that the soil plume is laterally defined by MW-7, B-4, MW-4,
<br /> MW-6, and MW-15, and MW-16. The EHD concurs with this conclusion.
<br /> In the WP, AGE recommends dual phase extraction (DPE) as the most effective option
<br /> for interim remediation at the site based on similar site conditions at 715 North Hunter
<br /> Street, where a pilot test for DPE was successful. AGE's technical justification in the WP
<br /> states "in general, this site depth to ground water, ground water flow direction, and soil
<br /> contamination, etc. is similar to those at the 715 North Hunter Street site". The EHD
<br /> agrees that there are general similarities in overall hydrogeology between these two
<br /> sites. However, the EHD can not concur with AGE's recommendation at this time to
<br /> implement a complete DPE system but would consider a pilot study for DPE. The EHD
<br /> directs submittal of a work plan for a DPE pilot test by June 7, 2010. Include a
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