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I ME <br /> 1 . The groundwater levels in the monitoring wells at former <br /> Exxon RS 7-1050 appear to be rising at present. All the <br /> wells now contain water, and if the rising trend con- <br /> tinues MW4 and MW5 will be sampled, with proper purging <br /> i methods, as soon as possible. If the groundwater levels <br /> fall below the bottoms of the wells again for an extended <br /> period, Exxon will submit a work p�.an to install an addi- <br /> tional well or wells in appropriate locations. <br /> - 2. The groundwater elevation data collected over the last <br /> two. years indicate a consistently shallow groundwater <br /> gradient towards the northeast. <br /> s EA has always practiced water sampling methods which are <br /> in accordance .with California LOFT manual and' RCRA guide- f <br /> dines. Water samples collected from former Exxon RS 7-" <br /> 1050 in the past were obtained using EA's QA/QC protocol <br /> unless otherwise noted. Turbidity.in groundwater samples . <br /> completed in low yielding, clay-rich;; "noxi -aquifer" for ` <br /> mations is unavoidable. Analysis of..the water samples <br /> 1 collected from Exxon RS 7-1050 have shown- a general <br /> decline in. contaminant concentration with time. This <br /> decreasing contaminant concentration may be due to <br /> fF natural biodegradation, by indigenous microorganisms in . <br /> the .soil and groundwater. <br /> t 4. Hydrocarbons were detected- in well headspacP samples <br /> 3 collected in 1987. There is insufficient control on the <br /> v nature of those well headspace samples to conclude _that. <br /> significant contamination exists in the unsaturated zone <br /> soil. Soil samples collected in August 198".. indicate <br /> that very- low concentrations of petroleum hydrocarboA.s <br /> are present in the soil beneath the site. <br /> Exxon Company, U.S.A. . propcses to conduct additional soil vapor <br /> assessments on:the .site to determine if: hydrocarbon vapors are <br /> still present in the unsaturated zone soils. <br /> e35l.7.1050/2-90/tx i2 <br /> � y <br /> r <br />