Laserfiche WebLink
Former Chevron Service Station No. 98632 <br />September 5, 2014 <br />575 West Grant Line Road <br />Page 4 of 4 <br />Tracy, California 95376 <br />specific data, or have been adequately addressed to reduce the hazards and risks <br />associated with vapor intrusion to acceptable numeric levels. <br />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 />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://vvvvw.waterboards.ca.00v/ust/cleanup/petitions.shtml for <br />information regarding the appeals process. <br />Based on the evaluation of the site status presented above, the EHD directs that a work plan 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 />-adtig4-oe/ 1,10(d_ <br />Victoria L. McCartney, REFIS Nuel C. Henderson, Jr., PG <br />Senior Registered Environmental Health pecialist 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 Etal, 216 East 12th Street, Tracy, California 95376