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' Project Quarterly Update Report--Revision 1 December 30, 1991 <br /> 9110 Thornton Road, Stockton, California Page 13 <br /> GROUNDWATER REMEDIATION SYSTEM <br /> 1 <br /> The groundwater treatment system experienced a mechanical breakdown as reported in the April 1991 <br /> project Quarterly Update Report. The system has not been reactivated at Southland's request due to <br /> the recent analytical results, which reported (1) no detectable TPH-as-gasoline levels in the samples from <br /> any of the monitoring wells, pumping wells, or nearby domestic wells for the period of January- March <br /> 1991, and (2) no detectable petroleum hydrocarbon constituents for the same wells for the period of <br /> April - September 1991, except for domestic well 9172. <br /> Southland has submitted correspondence to the San Joaquin County Department of Health to place the <br />' groundwater treatment system in dormant status, with reactivation criteria based on changes in water <br /> quality data. <br /> SUMMARY <br /> Groundwater monitoring data has documented a decrease In the water table elevation of approximately <br /> 1.91-feet during this reporting period. The average depth to water in September 1991 was approximately <br /> 49-feet below mean sea level (msl), compared to a depth of approximately 20-feet below rnsl in June <br /> 1986. The groundwater flow direction remained In an easterly direction at the average gradient of <br />' approximately 0.002 - 0.003 during the three month period. <br />' On August 26, 1991, a total of eight monitoring wells (two wells and two three-well clusters) were <br /> sampled and analyzed for the presence of BTEX and TPH-as-gasoline concentrations. Analytical results <br />' reported no detectable concentrations for any constituents In any of the samples. <br /> A select group of nearby domestic wells were sampled three times during the quarter and analyzed for <br />' the presence of BTEX and TPH-as-gasoline concentrations. All analytical results for the samples from <br /> the domestic wells reported non-detectable levels for all parameters analyzed, except for domestic well <br />' 9172 located on the Ivy Motel property. Detectable concentrations were reported for two of the three <br /> routine monthly sampling events although California state drinking water standards were not exceeded. <br /> 1 <br /> GROUNDWATER <br /> Ll <br /> -TECHNOLOGY, INC. <br /> I <br />