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A. <br /> Quarterly Monitoring ReJUCEIVED <br /> Soil & Assessment <br /> 103 North E Street JUL 2 9 1991 <br /> Stockton, Calf form&)VIRONMENTAL HEALTH <br /> PERMIT/SERVICES <br /> This report is to update groundwater test results taken at this <br /> site on June 10, 1991 relating to hydrocarbon contamination. <br /> Three ;monitoring wells (MW 9, 10, 11) were tested on June 10, <br /> 1991 for B.T.X.&E. and T.P.H. Monitor Wells 9 and 10 were also <br /> { sampled for chlorides, sulfates and total dissolved solids. <br /> SAMPLING PROCEDURE <br /> Mw 9 was purged using an airlift pump. MW 10 and 11 were purged <br /> using a 2" and 4" bailer. The gallons purged were recorded as <br /> well as the Ph. , Conductivity and Temperature. Samples were <br /> collected using bailer. Samples from each well consisting of one <br /> 1000 ML sample and one 40 ML sample. All samples were <br /> refrigerated and delivered to Eureka Laboratory using a chain of <br /> custody. Depths to groundwater were measured and recorded prior <br /> to purging. <br /> RESULTS <br /> "Site Plan" Plate 2 attached hereto gives monitoring well layout 111 <br /> and shows graphically the hydraulic gradient to be about 0.0014 <br /> �' feet/foot or 7.4 feet/mile with a direction N 15° E. <br /> j The groundwater elevation has decreased from -51 feet USGS in <br /> November 1990 to about -50 feet USGS in June 1991. This was <br /> expected but the future expected trend is for depth to <br /> i <br /> groundwater to continue to increase. <br /> Groundwater levels and gradients are presented in Table 2. <br /> Purging data, ph, conductivity and temperature are attached. <br /> A SUMMARY <br /> f <br /> jo detectable level of pur eable aromatics was found except for <br /> y „ F n� ., i` �'_. The TPH was <br /> non- e e tsile iri� t�i'ree wells <br /> Pest resu�.ta for 6-30-91 ars <br /> MM <br /> attached. <br /> RECOMMENDATION <br /> Continue to monitor the wells quarterly. Baned on number of <br /> - -- _' --- :benzene--levels above-an-action-_level_of__1.0ug/L,_ no clean-up is <br /> j <br /> time. <br /> recosnaended at this <br /> j <br /> i. <br /> r <br /> �1 <br />