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1 <br /> 507A <br /> Environmental Technology Inc <br /> was allowed for recovery after purging All monitoring wells were allowed to <br /> recover to 80 percent or more of their static water level condition At the time of <br /> groundwater sampling, neither free product nor sheen was noticed in any of the <br /> t monitoring wells Dedicated bailers were used for sampling from each of the <br /> wells, in order to eliminate cross examination <br /> The six water samples collected were stored in an ice chest at 4 degres Celsius <br /> Appropriate chain of custody was prepared prior to transporting to a State <br /> certified laboratory Del Mar Analytical, Irvine, CA performed the laboratory <br />' analyses All the water samples were analyzed for Total Petroleum <br /> Hydrocarbons (TPH) as gasoline (Volatile Fuel Hydrocarbons) and Benzene, <br /> Toluene, Ethylbenzene, and Xylenes (BTEX) following EPA Methods 8015/8020 <br /> The test data are presented in Table 2 <br />' All laboratory analytical results including QA/QC are enclosed with this letter <br /> report Table 2 also includes the historical data for wells MW-1 through MW-6 <br />' The groundwater level observations (Table 1) indicated a decrease of 0 47 foot to <br /> 1 21 Foot during the reporting period (5/93 and 9/28/94) Figure 2 presents <br /> the groundwater contour map It appears that the general groundwater flow <br />' direction is towards the north-northwest <br /> During the period 5/93 and 9/94, TPH (gasoline) concentrations in MW-1, MW- <br /> 3, and MW-4 have reduced from 170 000, 650, and 15,000 µ.g/l to 21,000, 88, <br /> and 12,000 µg/l respectively a TPH concentration contour map is presented in <br /> Figure 3 TPH concentrations in MW-2, MW-5, and MW-6 have increased from <br />' 170, 580, and 1,400 to 2,300, 600, and 3,400 respectively Similar trends in <br /> Benzene concentration at the wells were reported except at MW-4 where the <br /> benzene concentration had increased from 1,700 to 3,300 �Lg/l <br /> 1 Based on these and past observations SOTA proposes further delineation of the <br /> groundwater contamination plume as required by San Joaquin County SOTA <br /> will submit a workplan detailing the proposed additional site assessment on or <br />' before November 30, 1994 <br /> Should there be any questions regarding this transmittal please contact me or <br /> Eli Vedagiri at (619) 485-8100 <br />' q�.O+ESSjp <br /> Sincerely, <br /> t <br /> OTA E ronmental Technology Inc , <br /> Q: <br /> as <br /> iDa shana urthy PhD , P E <br /> Project Manager 4Z <br />' cc Steve Gilbert, U-Haul International, Phoenix, AZ �1j T� C/VIvL <br /> OF CAO <br />