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PUBLIC HEALTH SERVICES pPppl`V <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M D , M PH., Health Officer _ �P <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 4`` 0R`'� <br /> ' 209/468-3420 <br /> OP) � <br /> DARIN L ROUSE C: <br /> NLI\RKETING DEPT / EXXON COMPANY USA JUL 2 6 1990 <br /> ' PO BOY 4032 <br /> CONCORD CA 94524-4032 <br /> RE EXXON RAS T7-0137 _ SITE CODE: 1962 <br /> 1605 S EI Dorado Sc <br /> Stockton,CA., 95206 --- -_ <br /> ' Per your request, San,Joaquin County Public Health Services, Environmental Health Division (PHS- <br /> EHD) has recently re-evaluated the October 1998 "Work Plan for Confirmation Soil Borings m <br /> Support of a Request for Case Closure" previously submitted by EA Engineering, Science, and <br /> Technology and offers the following comments <br /> ' The proposal calls for four (4) Geoprobe push points to be placed at areas where previous <br /> subsurface soil investigations have indicated that petroleum constituents were detected at elevated <br /> concentrations Of particular concern to PHS-EHD is the absence of a confirmation soil boring at <br /> location "TK EN" where Total Petroleum Hydrocarbons as Gasoline UPH-G) were detected at <br /> 5,000 ring/kg from 16 feet below ground surface (` bgs) <br /> ' In order to better evaluate the effectiveness of the remedial effort, soil data from this point and <br /> depth (TKIN-16') will need to be obtained PHS-EID recommends that a slant push-point be <br /> placed in this area at a slight slant (10-15 degrees off vertical) from north to south By targeting the <br /> ' soil at 16' bgs and maintaining the shallow angle downward, soil samples could be collected at the <br /> depths listed in the proposal (16', 25', 35', and 45'bgs) and still remain very close to under the north <br /> end of the previous underground storage tank (UST) location It is hoped that this shallow angle <br /> ' would also provide data that would support potential conclusions for vertical delineation in this area. <br /> It is the understanding of PHS-EID that the proposed push-point at the extreme southwest corner <br /> of the property is to provide groundwater quality data in this quadrant since no monitoring well is <br /> located there PHS-EHD recommends that one or two soil samples be collected and analyzed from <br /> this location to verify the condition of the soil, in addition to the groundwater sample collection <br /> ' proposed <br /> If methanol or ethanol was ever a constituent of ETON gasoline, then these constituents are to be <br /> tested for in the soil and groundwater also The EPA Method for the testing of the oxygenates <br /> should be updated to include 8260B and the detection limits should be in the range of 5 0 ug/1 for <br /> water samples and no more than 10 mg/kg for the soil samples. <br /> k Di\F,ioa )t -Sin Jozgwr Cunt —faith Lire Ste* Ll, <br />