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Date November 30, 1998 <br /> ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> i <br /> Facility No: 02186 Address: 3212 North California Street, Stockton, California <br /> ARCO Environmental Engineer: Paul Supple <br /> Consulting Co./Contact Person: Pinnacle/Joel Coffman <br /> Consultant Project No: 20805-147.005 <br /> Primary Agency/Regulatory 1D No: Carol Oz, San Joaquin County Public Health Services <br /> WORK PERFORMED THIS QUARTER (Third 1998): <br /> 1. Groundwater samples were collected and submitted for laboratory analysis from monitoring wells MW-1 <br /> through MW-4 and vapor well VW-3. Analysis included oxygenates by USEPA Method 8260. <br /> 2. Pinnacle compiled and evaluated the groundwater monitoring data. <br /> WORK PROPOSED FOR NEXT QUARTER (Fourth 1998): <br /> 1. Pinnacle will continue to perform quarterly groundwater monitoring. The next sampling event is <br /> tentatively scheduled for December 1998. Groundwater samples from wells MW-1 through MW-4 and <br /> vapor well VW-3 will be collected and analyzed for total petroleum hydrocarbons as gasoline (TPHG) <br /> using U.S. Environmental Protection Agency (USEPA) Method 8015 Modified; and for benzene, <br /> toluene, ethylbenzene, and total xylenes (BTEX) and methyl tert-butyl ether (MTBE) using USEPA <br /> Method 8020. <br /> 2. As discussed with SJCPHS during the September 1998 meeting, Pinnacle will collect a depth discrete <br /> water sample from MW-1 during the fourth quarter sampling event. The water sample will be collected <br /> from the bottom portion of the screen interval by means of a discrete sampling device designed <br /> specifically to withdraw a sample from a targeted sample depth. The purpose of this sampling approach <br /> is to assess dissolved hydro-concentration at a depth that coincides with historical low groundwater <br /> elevation and UST operation in an effort to evaluate if a submerged zone of soil impact is present <br /> beneath the USTs. <br /> CP\D:IQMR�3RDQTR-112186Q398.DOC-98\1sg:1 <br /> Rcv.11/30/98 <br />