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5 <br /> PUBLIC hEALTH SpQu, <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 95201-0388 <br /> 209/468-3420 <br /> UNOCAL CORPORATiON JAN 0 9 -%.A <br /> BOB BOUST ; <br /> P O BOX 5155 RECEIVED <br /> SAN RAMON CA 94583 <br /> JAN 13 1997 <br /> RE: FORMER UNOCAL #2859 ODE: 1213 <br /> 1665 PACIFiC AVE FILE # �' <br /> STOCKTON CA RPT Q"'I TRA TEAL <br /> r <br /> San Joaquin County Public Health � al- I <br /> (PHSIEHD) has reviewed the Novebber 8 19 ance <br /> Summary July through September 1996" prepared by Pacific Environmental Group, <br /> Inc. for the above referenced site. The report is an evaluation of the Vapor Extraction <br /> (VES) System pilot test. <br /> The report states that the pilot test of this system was successful at removing nearly <br /> 2,000 pounds of hydrocarbons. The system is now operating at asymptotic levels <br /> meaning that the incremental benefit of continued operation has been lost. The report <br /> states that the internal combustion engine will be moved to another site during the <br /> fourth quarter of 1996. <br /> The efficacy of the VES system has been measured by,the influent of hydrocarbons <br /> into the system. Recent groundwater monitoring activities have also provided data on <br /> the effectiveness of the VES system. Since January of 1996 when the VES system <br /> was activated there does not seem to be any significant trends in hydrocarbon F <br /> concentrations in the two closest monitoring wells (MVV-3 and MW-2 ) to the vapor <br /> extraction wells. There is no clear correlation between removal.of vapor phase <br /> hydrocarbons and reduction of dissolved hydrocarbons in groundwater. <br /> The report refers to the vapor extraction system as a pilot test The purpose of a pilot <br /> test is to gather data on the economic and technical feasibility of a full scale ' <br /> remediation system. PHS/EHD recommends a report be compiled which will draw <br /> conclusions based on data gathered from 1196-9/96 on the feasibility of a full scale <br /> .VES system for this site. The fact that the system went asymptotic with such a large <br /> mass of hydrocarbons remaining in the subsurface indicates either a_poorly designed <br /> System or a subsurface environment Unfavorable to VES technology. <br /> e assessment of the lateral gAent of <br /> groundwater contamination is complete, the assessment of soil contamination is <br /> EXHIBIT 2 <br /> A Division of San Joaquin County Health Care Services . <br />