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i • <br /> San Joaquin County <br /> �. <br /> Environmental Health Department DIRECTOR <br /> G Donna Heran,RENS <br /> a� �"�g'„ •? 600 East Main Street <br /> / <br /> Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> ,. <br /> Robert McClellon,REHS <br /> .� Jeff Carruesco,REHS,RDI <br /> C��iPOR N`P Website: www.sjgov.org/ehd Kasey Foley,REHS <br /> Phone: (209)468-3420 <br /> Fax: (209)464-0138 <br /> June 25, 2010 <br /> Raymond Greer Albert &Wanda Veldstra <br /> Raymond Greer Construction, 15634 S. Steinegul Road <br /> 1601 Cabrillo Court Escalon, CA 95320 <br /> Modesto, CA 95355 <br /> Subject: Former Greer Construction <br /> 15634 S. Steinegul Road <br /> Escalon, CA 95320 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Feasibility <br /> Study (Study), dated June 11, 2010, submitted on your behalf by ATC Associates Inc. (ATC) <br /> and has the following comments. <br /> In the Study, ATC reports the results of an ozone infusion bench scale test, and compares four <br /> remedial methods for possible use on the impacted groundwater at this site: groundwater pump <br /> and treat; oxygen sparging; ozone sparging; and natural attenuation. Remediation of vadose <br /> zone soil contamination at this site has been successfully accomplished by use of soil vapor <br /> extraction, but persistent concentrations of contamination remain in the groundwater. The <br /> purpose of the evaluation was to identify the most cost-effective technology to reduce the <br /> impact to groundwater and bring the site to final regulatory closure. <br /> The ozone infusion bench-scale test utilized contaminated soil and groundwater samples, and <br /> clean soil samples collected from the site. The results of the test indicate that while the ozone <br /> works very well on breaking down the petroleum hydrocarbon contaminants, the reaction <br /> byproducts hexavalent chromium and bromate were produced, and attenuated at a slow rate, if <br /> at all. Additional tests indicate better results were obtained with lower dose applications of <br /> ozone, but that formation of bromate increased over the duration of the test. <br /> ATC recommended conducting an insitu pilot test for ozone infusion to study the effects in the <br /> field. If favorable pilot test results are obtained, ATC further recommended preparation of a <br /> Remedial Action Plan (RAP) that includes contingency plans to mitigate the generation of <br /> hexavalent chromium and bromate in the field, should the byproducts concentration trends <br /> behave similarly as in the lab tests. <br /> The EHD cannot concur with this recommendation at this time and needs additional information <br /> to further evaluate the test results and their proper application to a pilot test. Normally, it's a <br /> successful bench-scale test that leads to a pilot test. In this test, the concentrations of bromate <br /> continued to increase during the extended attenuation test and the possible reasons for this <br /> were not fully explored. Prima, the lab conducting the test, proposed that permanganate formed <br /> during the test caused the increased production of hexavalent chromium and bromate. The <br />