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Q� ('03 [P...`\\j <br /> ENVIRONMENTAL HEALTH DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> Donna'K.Heran,R.E.H.S. Carl Borgman,R.E.H.S. <br /> ` < Director 304 East Weber Avenue, Third Floor Mike Huggins,R.E.H.S.,R.D.I. <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 <br /> �:• Douglas W.Wilson,R.E.H.S. <br /> • .. <br /> Program hone: 209 Manager Tele 468-3420 Margaret Lagorio,R.E.H.S. <br /> FoR <br /> P ( ) <br /> Laurie A.Cotulla,R.E.H.S. Fax: (209) 464-0138 Robert McClellon,R.E.H.S. <br /> Program Manager Mark Barcellos,R.E.H.S. <br /> ' ROBERT J COCHRAN (I M C M EIU �. AUG 11 200A <br /> CHEVRON ENVIR MGMT COMPANY AUG 12 2004 <br /> PO BOX 6004 <br /> SAN RAMON CA 94583-0904 By.-------------------- <br /> ' RE: Chevron Bulk Terminal #1001621- UST Site Code: RO#1471 <br /> 22888 S. Kasson Rd. <br /> Banta, CA. <br /> San Joaquin County Environmental Health Department (EHD) has reviewed UST Site <br /> Assessment Report dated July 16, 2004 as submitted by Secor International on July 19, <br /> 2004 and has the following comments. <br /> On May 21,_2003 EHD notified Chevron that corrective action was required to <br /> investigate the unauthorized release noted after the "transmix" UST removal on March <br /> 5, 2003. On August 28, 2003 EHD approved a work plan to meet the requirements and <br /> four soil borings were installed in September 2003. <br /> Laboratory analyses for the soil samples collected from the four borings indicated low <br /> levels of petroleum were detected in about half of the samples. Ground water samples <br /> collected from the two soil borings and two monitoring well installations indicated that <br /> elevated concentrations of total petroleum hydrocarbons as diesel and gasoline (TPH-d <br /> and TPH-g) as well as BTEX, MtBE, TBA, TAME, and 1,2-DCA, have impacted the area <br /> in and around the former 'trans mix' UST. <br /> Monitoring well, MW-68A, was installed in Jhe former UST pit and the water sample from <br /> it, "MW-68A-W", showed 4,400 ug/I of TPH-d. Monitoring well MW-67UA was installed <br /> 50 feet northeast and down gradient from the UST pit and the ground water sample <br /> from it, "MW-67UA-W", showed TPH-d at 4,900-i g/I. Soil boring USB-2 was installed <br /> --160 feet north/northeast of the former UST pit and the ground water grab sample from <br /> it indicated 2,100,000 ug/I of TPH-d. <br /> The increasing TPH-d concentrations in the ground water samples, as the sampling <br /> points get further away from the UST, does not appear to fit the typical pattern of plume <br /> migration from an UST. Without additional proof, EHD cannot consider the very high <br /> TPH-d in USB-2 as part of the plume emanating from the former UST release. With <br /> above ground storage tanks (AST) piping in this area, EHD does not consider this area <br /> as part of the UST investigation. The Central Valley Region Water Quality Control Board <br /> • (CVRWQCB) may require further investigation of this area and Chevron should not <br /> include this area in UST work plans. <br />