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PUBLIC HEALTH SERVICESUJAI <br /> SAN JOAQUIN COUNTY <br /> JOGI KHANNA M.D.,M.P.H. <br /> Health Officer P <br /> P.O. Box 2009 •(1601 East Hazelton Avenue) •Stockton,California 95201 <br /> ikoR�'• <br /> (209) 468-3400 <br /> CHUCK CARMEL <br /> ARCO PRODUCTS COMPANY • l <br /> P O BOX 5811 / FEB 2 19913 <br /> cc <br /> SAN MATEO CA 94402 <br /> RE: Village ARCO #2133 SITE CODE: 1021 <br /> 2908 West Benjamin Holt <br /> Stockton CA 95207 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has completed <br /> review of the "Fourth 1992 Quarterly Report" dated January 12, 1993 and the "Addendum to the Work <br /> Plan for Drilling" dated January 19, 1993,both prepared by Brown and Caldwell (BC). PHS/EHD has the <br /> following comments for your consideration. <br /> PHS/EHD requested, in correspondence dated November 23, 1992, additional investigation to determine <br /> the boundaries of soil and groundwater contamination. PHS/EHD also requested a more timely submittal <br /> of quarterly reports. Thank you for the submittal of both a work plan and the quarterly report. Please <br /> continue efforts to submit quarterly reports within 45 days from the date of sampling. The first quarterly <br /> report for 1993 should be submitted by March 16, 1993. <br /> Groundwater contamination was evidenced by the October 29, 1992 sample results from monitoring wells: <br /> BHD-1, E-2, E-4, E-8, E-9, E-10, E-11, and E-12. PHS/EHD requested additional investigation in order to <br /> delineate groundwater contamination detected specifically in samples from E-11 (benzene 360 ppb) and E- <br /> 12 (benzene 6.7 ppb). The work plan proposed the installation of a monitoring well west of E-12; <br /> however, PHS/EHD disagrees with this proposed location. During the February 9, 1993 telephone <br /> conversation with you and PHS/EHD staff, it was agreed that the proposed monitoring well would be <br /> located further south, in order to better investigate contamination evidenced in E-11. Additional <br /> monitoring wells may still be necessary to define the extent of groundwater contamination. <br /> Soil contamination was evidenced during the investigation by field observations and analytical results from <br /> samples collected, in the southern area of the site, during the installation of monitoring wells, E-2 and E- <br /> 11 and during drilling of soil borings,AS-6 and AS-7. PHS/EHD requested additional soil investigation in <br /> order to determine the boundaries of soil contamination both for purposes of remediation and <br /> confirmation. PHS/EHD also requested investigation of the possible septic tank and leach lines which <br /> were originally installed in the southwestern area of the station on the neighboring parcel and for which <br /> there is no record of destruction. Leach lines provide conduits which facilitate the migration of <br /> contamination. <br /> The work plan addendum proposed one soil boring. One soil boring cannot adequately characterize the <br /> southern area of the site which is approximately 150 feet in length. PHS/EHD recognizes the reluctance <br /> to encroach on the neighboring parcels south of the site which are residential; therefore, consideration <br /> should be given to performing multiple slant borings, originating on site, to investigate the extent of soil <br /> contamination. <br /> A Division of San Joaquin County Health Care Services <br />