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N� <br /> ENVIRON&ENTAL HEALTAEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> Program Coordinators <br /> Direectorctor <br /> N' ?� <br /> Donna K. HR.E.H.S. 304 East Weber Avenue,Third Floor Carl Bergman,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 /> • Cq':;,,.„:.�j�Q'• Assistant Director Telephone: 209 468-3420 Margaret Lagorio, R.E.H.S. <br /> ticoe 1> ( ) 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 /> APR 2 0 2007 <br /> RAYMOND GREER <br /> RAYMOND GREER CONSTRUCTION ALBERT & WANDA VELDSTRA <br /> 2080 MC HENRY STE 100 15634 STEINEGUL ROAD <br /> ESCALON CA 95320 ESCALON CA 95320 <br /> RE: Former Greer Construction SITE CODE: 2021 <br /> 15634 Steinegul Road <br /> Escalon CA 95320 <br /> San Joaquin County Environmental Health Department (SJC/EHD) has reviewed <br /> Monitoring Report 4th Quarter 2006(Report) dated March 23, 2007, submitted on your <br /> behalf by ATC Associates Inc. (ATC) and has the following comments. <br /> The Report documents a routine quarterly groundwater monitoring and sampling event <br /> that was conducted in November 2006, and monthly operation, maintenance & sampling <br /> of the onsite remediation system conducted during 4a' quarter 2006. Operation of the <br /> soil vapor extraction (SVE) remediation system began in September 2005. Vapor <br /> sample data indicates the SVE system is effectively removing petroleum hydrocarbon <br /> contamination from the soil. <br /> Review of site data indicates the groundwater contamination has not been adequately <br /> defined. Currently all onsite monitoring wells report contamination. Offsite monitoring <br /> well MW-8 and the onsite domestic well are the only wells reporting non-detect results <br /> for all constituents analyzed. The deepest monitoring well is MW-6, with a screen <br /> interval from 95-100 feet below surface grade (bsg). This well currently reports the <br /> highest concentrations of methyl tertiary butyl ether(MtBE) and 1,2-dichloroethane <br /> (1,2-DCA) contamination at 240 and 530 micrograms per liter(µg/I) respectively. A grab <br /> groundwater sample collected at 124 feet bsg from a cone penetrometer test (CPT) <br /> boring in 2004 reported 3.9 µg/I 1,2-DCA. This contamination must be defined with a <br /> deep, discretely screened monitoring well. The shallow groundwater contamination is <br /> currently only defined to the south, by well MW-8. <br /> Review of the reported groundwater elevations over the history of the site reveal an <br /> unusual trend. Reported elevations in wells MW-2, MW-3 and MW-4, the wells located <br /> on the west side of the property, consistently are 5-6 feet higher than groundwater <br /> elevations reported in all the other wells, including MW-6 which is only about 20 feet <br /> from MW-2. This unusual pattern makes it appear that the general groundwater flow <br /> direction is to the southeast, towards the onsite domestic well, which is opposite of the <br /> groundwater flow direction reported at other sites in the Escalon area. You consultant <br /> should be providing an explanation for this unusual groundwater elevation pattern. <br />