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EA Engineering,Science,and T-hnology EA Western Regional Operations <br /> 41 Lafayette Circle <br /> Wayeae,CA 94549 <br /> Telephone:510-283-7077 <br /> Fax:510-263-3894 <br /> OD <br /> 15 July' .1992 <br /> C <br /> VII <br /> Marla D. Guensler <br /> A U 6 19 1992 <br /> Environmental Engineer E N V I RON fit,ENITAL HEALTH <br /> Exxon Company, U.S.A. <br /> 2300 Clayton Road, Suite 1250 <br /> Concord, California 94520 <br /> RE: Summary of meeting, Exxon RS 7-3942, 4444 Peishing Avenue, Stockton, California <br /> Dear Ms. Guenster: <br /> A meeting was held at the office of San Joaquin County Public Health Services on 18 June 1992 <br /> to discuss the potential impact that groundwater extraction and re-injection of treated water <br /> proposed by Exxon would have on the nearby Shell site. Attending the meeting were Elizabeth <br /> Thayer, Central Valley Regional Water Quality Control Board, Harlin Knoll, Margaret Lagorio, <br /> Steve Schneider, and Michael Collins, San Joaquin County Public Health Services; Daniel Kirk, <br /> Shell Oil Company; Brian Garber, Aegis Environmental, <br /> Inc. (consultant to Shell); Marla <br /> Guensler, Exxon Company, U.S.A.; and Terry Winsdr and Douglas Orarn, EA Engineering, <br /> Science, and Technology (consultants to Exxon). <br /> Shell OU Company requested the meeting to discuss the impact that re-injection of water <br /> proposed by Exxon would have on Shell's site located west across Pershing Avenue. Shell's <br /> position was that the hydrocarbons found in soil and water samples taken from monitoring well <br /> MW8 installed for Exxon by EA, located in the sidewalk adjacent to Shell's station, result from <br /> upgradient migration of free-phase hydrocarbons from Exxon's former tank field and would be <br /> left behind if water is re-injected into wells along Pershing Avenue. Shell indicated that <br /> analytical results of recent quarterly monitoring did not define petroleum hydrocarbons in any <br /> samples collected from the four wells on the site. Shell cited the following evidence to support <br /> their contention that no further investigation or remediation at their site is warranted: <br /> 1. No petroleum hydrocarbons (Total Petroleum Hydrocarbons as gasoline <br /> (TPH-g) or benzene, toluene, ethylbenzene, or xylenes (BTEX) have <br /> been found in the groundwater samples collected from monitoring wells <br /> MWI-3, and water samples obtained from monitoring well MW4 on <br /> 21 January 1992 contained 110, 1.2, 1.2, and 1.0 pg/L of TPH-a, B, T, <br /> and X, respectively. <br /> 2. The soil samples analyzed from the soil borings for monitoring and <br /> vapor extraction wells MW1, MW2, N 1W.13, VEW-I, and VEW-2 <br /> contained a maximum of 1.2 mg/kg TPH'` <br /> g and 0.13 mg/kg benzene <br /> (well VEW-1). <br /> 3. Vapor monitoring conducted during the pilot soil vapor extraction test <br /> from well VEW-2 contained a maximum concentration of 90 ppmv. <br /> 4. Concentrations of hydrocarbons declined "asymptotically" to "zero" as <br /> the 72-day pilot extraction test progressed, indicating that whatever <br /> petroleum remained in the soil after the tank removal was "cleaned-up." <br />