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t <br /> i <br /> A.Monitoring <br /> GENE �g <br /> Quarterly Monitoring Re �,� <br /> Soil & Assessment f UL 2 9 .� <br /> 103 North E Street ►.gi <br /> Stockton, Cal ifornENVIRONMENTAL 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, & 1Z) 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. P1W 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. ,,amples 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 /> 4 <br /> RESULTS <br /> "site Pian" Plate 2 attached hereto gives monitoring well layout <br /> and shows graphically the hydraulic gradient to be about 0.0014 <br /> feet/foot or 7.4 feet/mile with a direction N 150 E. <br /> 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 /> groundwater to continue to increase. <br /> Groundwater levels and gradients are presented in Table 2. <br /> Purging data, ph, conductivity and temperature are attached. f <br /> SUMMARY. <br /> o detectable level of purgeable aromatics was found exce t far <br /> P <br /> Benzene at 13Q; Ug/,L;, in .W 9.-6rd 1.7 Ug/L in..M 11M; The TPH was <br /> nont:3eie&EAble n all three wells Test `results for 5-10-91 are <br /> attached. <br /> RECOMMENDATION <br /> Continue to monitor the wells quarterly. Based on number .of <br /> benzene levels . abave an action level of L.O :ug/L, no clean-up is <br /> ., recommended at .this time. <br />