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�CESPUBLICY-IEALT.H SERou <br /> gyp,....••',. C <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Ernest M. Fujimoto, M. D:, M.P.H., Acting Health Officer-"> �("�� <br /> 304 E. Weber Ave., Third Floor • P. O. Box 388 • Stockton, CA <br /> 2091468-3420 <br /> MORESCO VINEYARDS MAILED MAR 2 71996 <br /> CIO MIKE MCGRANAHAN <br /> PO BOX 5018 <br /> MODESTO CA 95352-5018 <br /> RE: WORKPLAN REVIEW, 16865 GAWNE ROAD,.STOCTON SITE CODE: 2233r' <br /> San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) Site Mitigation staff have <br /> recently reviewed the Work lan for Additional Subsurface Investigation prepared by Geological Technics Inc. <br /> (GT) and are providing the following comments. <br /> In an effort to cost effectively characterize Leaking Underground Fuel Tank sites (LUFI"s)'PHS/EFID recommends <br /> the following amendments for consideration. When implemented this approach may provide significant and <br /> comprehensive contemporary data for decision making processes regarding health risk and contaminant fate and <br /> transport modeling assessments, remediation alternatives including the potential for.natural attenuation, and <br /> ultimately, timely site closure certification <br /> PHS/EHD has discussed this approach with George Lockwood of the Underground Storage Tank Cleanup Fund <br /> Program (USTCFP) in detail and takes'this opportunity to inform all responsible parties and consultants to utilize <br /> the bid process in order to contain costs and seek preapproval for-site specific costs prior to engaging in site <br /> activities to avoid jeopardizing reimbursement. <br /> Conceptually, PHS/EHD concurs with GT proposals for soil boring locations. PHS/EHD will require one soil <br /> boring in the original tank pit area, preferably in a downgradient position through native soil,to obtain the <br /> geotechnical and chemical information discussed below. Additional geotechnical analyses should be included to <br /> refine the definition of vadose, capillary fringe, and saturated zone characteristics at this site. These analyses <br /> should include falling head permeability, %moisture, porosity, dry bulk density, soil pH,'CEC, %organic content <br /> and C:N:P ratios for selected significantly different liihological units encountered while boring. Itis recognized <br /> that a multitude of the analyses may be obtained through single tests substantially reducing the overall cost. <br /> Contractors should be chosen for field�investigative activities which have the capacity to obtain field screening <br /> information in the form of soil gas!,�analyses including VOC empirical data potentially providing crucial <br /> information for subsequent soil boring locations within the same mobilization event. <br /> Conceptually,PHS/EHD concurs with GT proposals for'Fuel Hydrocarbon Constituent(FHC's)analyses. However, <br /> additional soil analyses is required. This analysis must include Methyl Tertiary Butyl Ether(MTBE) analysis, the <br /> current method recommendation is 8020 with an 8260 confirmation for all preliminary MTBE detection's in order <br /> to eliminate the potential for false positives. This scenario.is also requiied for all soil samples submitted for <br /> analysis until it is determined that this FHC oxygenate is not present at the site. <br /> PHS/EHD and USTCFP recommend a well survey including construction details for all wells in the vicinity and a <br />! general health risk assessment which may reveal any receptors to be potentially impacted during assessment or <br />{ remediation activities. The general risk assessment should include potential preferential contaminant migration <br /> pathways (underground utility trenches or structures), potential recharge areas (canals, surface water collection <br /> basins) and similar parameters which may enhance site closure confidence. <br /> A Division of San Joaquin County Health Care Services <br />