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1 Bank of Stockton Page 4 <br />' Wmter 1996 Quarterly Morutormg Report <br /> Project No 358 2 <br /> APn18,19% <br />' 2.0 FINDINGS AND DISCUSSION <br /> 1 The laboratory analytical data from this monitoring event show that some <br /> petroleum hydrocarbons were discovered in these wells as listed below. <br />' MW-1 <br /> In monitoring well MW-1, the VOCs detected were benzene (1 ppb), toluene (0.8 <br /> ppb), and xylene (0.9 ppb). No detectable TPH was found This level of VOCs is <br />' similar to that found in the prior monitoring event m November 1995 but the <br /> benzene is only 1/2 of the December level <br /> MW-2 <br /> Non-detectable levels of TPH and VOC's are present in the sample collected <br />' MW-3 <br /> Non-detectable levels of TPH and VOC's are present m the sample collected. <br /> MW-4 <br /> In monitoring well MW-4, the only detectable VOC was benzene (0.5 ppb). No <br /> Idetectable TPH was found. This level of VOCs is similar to that found in the <br /> prior monitormg event in November 1995, although slightly lower <br /> 3.0 CONCLUSIONS <br /> The following conclusions have been drawn regarding this quarterly <br /> groundwater sampling event: <br />' • The direction of groundwater flow and gradient are consistent with prior <br /> monitoring events as reported by Geological Audit Services and <br /> Geological Technics Inc <br /> • Low levels of VOCs continue to persist in monitoring wells MW-1 and <br /> MW-4. <br /> • As shown in Summary Table 2, there is a clear trend ofadu <br /> gr ally <br /> reducing levels of BTEX compounds, and there are no detectable total <br /> petroleum hydrocarbons (TPH) in the existing wells It is noted however, <br /> that there is no directly down-gradient monitoring well and it is possible <br /> that such a down gradient well could reveal the existence of additional <br />