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N Date November 13, 2001 ARCO QUARTERLY STATUS REPORT Facility No 6100 Address 25775 Patterson Pass Road, Tracy, CA ARCO Environmental Engineer Paul Supple Consulting Co/Contact Person Delta Environmental Consultants, Inc /Jay_R Johnson Consultant Project No D000-340-1 Primary Agency/Regulatory 1D No Margaret Lagorio, San Joaquin County Public Health Serivices BRIEF HISTORY Four gasoline UST's, one waste oil UST, and associated product piping were removed in 1987 Between 1991 and 1995 a total of 31 soil borings were drilled to depths between 26 and 115 feet below ground surface (bgs) Twenty vapor wells (VW-1 through VW-20) were installed in selected borings Pinnicle • Environmental Solutions, Inc submitted a request for "No Further Action" to the RWQCB on February 1, 2000 The RWQCB denied the request, and requested a groundwater investigation One soil boring was drilled at the site to a depth of approximately 200 feet bgs in August 2000 Groundwater monitoring well MW-1 was installed in this boring to a depth of 120 feet bgs During well development, floating product was observed in the well Floating product has been removed manually from the well on a weekly basis Following a meeting between the RWQCB, SJCPHS, and ARCO on January 10, 2001, Delta submitted a work plan for additional assessment of subsurface conditions beneath the subject site This work was implemented during the thud quarter 2001 A report on the site assessment activities performed during the third quarter 2001 will be submitted to the RWQCB and the SJCPHS in the fourth quartrer 2001 WORK PERFORMED THIS QUARTER (Third 2001) 1 Between August 29 and September 7, 2001, Delta drilled six soil borings (B-33 through B-38) to depths between 135 and 140 feet bgs The borings were cored continuously, and downhole geophysical logs were prepared for each boring before they were properly destroyed Sod samples from the borings were submitted for chemical analysis 2 Between September 10 and 22, 2001, Delta installed four well clusters adjacent to borings B-33 thorugh B-36 In each cluster the shallow well was installed to a depth of 65 feet bgs, and the deep well was installed to a depth of 95 feet bgs 3 Delta continued to measure free product in well MW-1 (0 40 to 1 01 feet thick), and free product removal continued during the third quarter Free product was also observed in well VW-4 (0 01 to 0 02 feet thick), and free product removal was initiated in this well, too Product thicknesses and quantities removed for well MW-1 are summarized in Table 1 4 Delta continued to check for the presence of water in may of the vapor wells Water was present in vapor wells VW-1, VW-2, VW-4, VW-5, VW-6, and VW-14 These wells have typically contained groundwater since mearements were collected during the groundwater investigation T%new QMslAmo_6100_3Q01 DOC Delta