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ENVIRONMENTAL HEALTH DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> Donna K.Heran,R.E.H.S. CarlBorgman,R.E.H.S. <br /> a 304 East Weber Avenue, Third Floor <br /> Director Mike Huggins,R.E.H.S.,R.D.I. <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. <br /> �.. <br /> 1%P• Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> q .........a. <br /> oa Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S. <br /> Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. <br /> AUG 1 6 2004 <br /> JERRY MOORE <br /> MOORE PETROLEUM <br /> 976 W MARIPOSA AVE <br /> STOCKTON CA 95204 <br /> RE: Workplan for a Limited Subsurface Site Investigation <br /> 5491 F Street <br /> Banta CA 95304 <br /> San Joaquin County Environmental Health Department (EHD) has received and <br /> reviewed Workplan Addendum Letter for a Limited Subsurface Site Investigation <br /> (WPAL) dated 02 June 2004, prepared by Apex Envirotech, Inc. (AEI) on your <br /> behalf. The WPAL was prepared in response to an EHD directive issued by letter <br /> dated 12 May 2004 to include.a boring/monitoring well for vertical assessment of <br /> impacted ground water and an EHD recommendation for relocating monitoring <br /> well MW-17 to more tightly delineate the plume of impacted ground water. <br /> AEI addresses the EHD directive in the WPAL by proposing to install a cone <br /> penetration testing (CPT) boring near MW-12 to identify permeable sand units in <br /> the saturated zone to a target depth of 80 feet below surface grade (bsg), and <br /> collect ground water samples from the sand intervals identified in the Driller's log <br /> for the domestic well of interest. EHD notes that hydropunch-like ground water <br /> samples should be collected for laboratory analysis from each significant interval <br /> of relatively higher permeability identified in the CPT log that may act as a lateral <br /> migration pathway for the dissolved contaminants. Information from the CPT is <br /> intended to be utilized for designing a.sentinel well to protect the Domestic water <br /> supply well east of the site. The CPT• should be located in line between the <br /> dispensers on the subject site and the domestic well of interest. <br /> AEI also intended the proposed CPT and related sampling to be utilized to <br /> complete the vertical assessment of impacted ground water on the site. EHD had <br /> also recommended installation of a CPT boring in the suspected source area, or <br /> slightly down-gradient of it for this purpose, although this may not have been <br /> stated as clearly as it could have been in the 12 May 2004 letter. EHD believes <br /> the location of the AEI-proposed boring, approximately 60 to 80 feet from the <br /> suspected source area, may be too far for this purpose. Please include a second <br /> CPT boring with ground water sampling in the suspected source area near the <br /> dispensers. <br />