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Former Beacon Station No. 12474 April 10,2002 <br /> Califomia wter Monitoring Report <br /> located in Davis, California. The samples were analyzed for total petroleum hydrocarbons <br /> as gasoline (TPHg), the volatile aromatic compounds benzene, toluene, ethylbenzene and <br /> total xylenes (BTEX) and the fuel oxygenate, methyl-t-butyl ether (MTBE) by <br /> Environmental Protection Agency (EPA) Method 8260B. <br /> Results <br /> Depth-to-groundwater measurements were subtracted from the surveyed TOC elevations to <br /> calculate groundwater elevations. Groundwater elevation data, as summarized in Table 1, <br /> were used to construct the groundwater contour map as shown on Figure 2. Only <br /> monitoring wells in which the groundwater levels intersected the screened intervals were <br /> used to construct the groundwater contour map. Groundwater generally flows eastward to <br /> southward across the site under a shallow gradient of less than 0.001. <br /> Groundwater analytical results are summarized in Table 1. Benzene concentration data from <br /> this sampling event were used to construct a benzene isoconcentration map as shown on <br /> Figure 3. Analytical reports and chain-of-custody documents are contained in Attachment <br /> C. Historical groundwater level and analytical data collected prior to 1998 are summarized <br /> in Tables I and 2 in Attachment D. <br /> Recommendations <br /> Horizon recommends continued quarterly monitoring at the site. A Problem Assessment <br /> Report/Corrective Action Plan is being developed which will describe the nature and extent <br /> of petroleum hydrocarbons in the soil and groundwater and contain recommendations for <br /> remedial actions. <br /> Report Distribution <br /> We recommend a copy of this report be forwarded to: <br /> Mr. Michael J. Infurna Mr. Gordon Boggs <br /> Environmental Health Division CRWQCB - Central Valley Region <br /> San Joaquin County Public Health Services 3443 Routier Road, Suite A <br /> P.O. Box 2009 Sacramento, California 95827-3098 <br /> Stockton, California 95201 <br /> Mr. Sohail Bafaiz <br /> 392 West Harder Road <br /> Hayward, California 94544 <br /> 474gmr02Q 14.doc <br /> 1474.45 2 HORIZON ENVIRONMENTAL INC. <br />