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`Mobil Oil Corporation <br /> MAR 2 7 9992 <br /> ENVIRONMENTAL HEALTH <br /> iJ! <br /> March 24 , 1992 PERMIT/ EICS <br /> Ms. Mary Meays FORD_ 1 0BIL BULK PLANT <br /> San Joaquin County 500 EASTI'.GRAMMINE ROAD <br /> Environmental Health Division TRACY, CALIFORNIA <br /> 1601 'East Hazelton Ave. <br /> Stockton, CA- 9520.1 <br /> I _ Dear Ms. 'Meays: <br /> Enclosed for your information is the quarterly monitoring <br /> report dated_ March 6, 1992,. for subject location.. The <br /> aver.age. depth to the ground water was 11 feet and the <br /> gener' - ground water hydraulic gradient onsite was 0. 013 <br /> foot/foot to the -northeast. TPHG and Xylenes were present . <br /> only in the ground water samples collected from AW-3 (610 ,' <br /> ppb and 0.48ppb) . The laboratory reported the -presence of <br /> TPHD concentrations in all ground water samples collected; <br /> as �quanti.fied against a diesel standard—These results are <br /> anomalous due to:,fact that. all .prior analysis. of TPHD (with <br /> f the exception- _6f AW-3) 'showed that detectable concentrations <br /> of TPHD were riot present in any_,of the. ground water samples <br /> collected. The°-historical absence of BTEX- constituents <br /> f (.except. for the October 2, 1990 data for AW '3) in the 'ground <br /> water- samples_ indicates that gasoline range.:hydrocarbons <br /> have ' not- impacted-_ ground water in the vicinity of the <br /> monitoring wells. <br /> -In addition to the manual pump outs for interim remediation, <br /> additional=.characterization activities are scheduled for the <br /> f irst week of April. <br /> If -you have any questions, Please feel free to call me at- <br /> (818-)- 95.3-2626. <br /> Sincerely, <br /> Stephan Pao <br /> Field Engineer II <br /> enclosure <br /> Ms. E1-izabe'th. Thayer (w/ enclosure) rw. <br /> ..RWQCB- -Central Valley Region Environmental <br /> 344.3 Routier.-Road Awareness <br /> Sacramento, CA' 958.27 <br /> { <br />