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Former Chevron Service Station No. 98632 September 5, 2014 <br /> 575 West Grant Line Road Page 4 of 4 <br /> Tracy, California 95376 <br /> E <br /> specific data , or have been adequately addressed to reduce the hazards and risks <br /> associated with vapor intrusion to acceptable numeric levels. <br /> 5. CRA addresses the direct contact and outdoor air exposure impediment to closing this <br /> site by stating that extensive excavation to 10 . 5 feet bsg in the former used-oil <br /> UST/sump/hoist area has been performed . This may be the case ; however, review of <br /> soil data indicates that significant concentrations of petroleum hydrocarbon <br /> contamination have been reported at or above ten feet bsg in soil samples collected <br /> throughout the site and not necessarily in the excavation areas. Although natural <br /> attenuation has probably had some effect reducing the contaminant mass on site, the <br /> EHD cannot justify disregarding the reported benzene concentrations of 18 milligrams <br /> per kilogram (mg/kg) , 24 mg/kg , and 17 mg/kg in soil samples collected from MW-2, <br /> MW-3 and MW-4, respectively, without definitive data when active remediation has not <br /> taken place and the three wells are located outside the known area of excavation. <br /> 6. Groundwater measurements in April 2014 indicate that depth-to-water is approximately <br /> six to seven feet bsg . Based on the analytical results reported for groundwater samples <br /> collected in April 2014, it appears that groundwater concentrations are nearing water <br /> quality objectives and additional groundwater sampling is not warranted at this time. <br /> Please suspend groundwater sampling at this site until directed otherwise by the EHD. <br /> In 2014 GWMR, CRA formerly requested case closure consideration ; the evaluation of the <br /> potential vapor intrusion issue presented above prevents the EHD from concurring with the <br /> closure request at this time and the closure request is denied . This decision is subject to appeal <br /> to the State Water Board, pursuant to California Health and Safety Code Section 25296 .40 (a) <br /> ( 1 ) , (Thompson-Richter Underground Storage Tank Reform Act — Senate Bill 562) . Please <br /> contact the State Water Board Underground Storage Tank Program at (916) 341 -5752 or visit <br /> the State Water Board website at http://www.waterboards. ca , gov/ust/cleanup/petitions. shtmi for <br /> information regarding the appeals process. <br /> Based on the evaluation of the site status presented above, the EHD directsthat a work pan be <br /> submitted to this agency by 05 November 2014 to collect sufficient data to quantify the health <br /> risk hazard posed to occupants of the site; this may include collecting gas/vapor samples from <br /> the crawl space beneath the onsite trailer. <br /> If you have any questions or concerns, please contact Vicki McCartney at (209) 468-9852 or by <br /> e-mail at vmccartney@sjcehd . com . <br /> Sincerely, <br /> Victoria L. McCartney, REHS Nuel C. Henderson , Jr. , PG <br /> Senior Registered Environmental Health b1pecialist Engineering Geologist <br /> c: Mr. James P. Kiernan , PE , Conestoga-Rovers & Associates, 10969 Trade Center Drive, <br /> Suite 107, Rancho Cordova , California 95670 <br /> Ms, Cori Condon , PG , Chg , California Regional Water Quality Control Board Central Valley <br /> Region , 11020 Sun Center Drive, Suite 200, Rancho Cordova , California 95670 <br /> Stella I . Richman Tr Eta[, 216 East le Street, Tracy, California 95376 <br />