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yeolog4uI recfur aIna Page 9 Site Conceptual Model Report Marci Property Project No 7012 August 23,2004 ' the site The purpose of the survey was to locate any municipal, domestic, or agricultural wells within the 2,000-ft radius and to determine, if possible, the construction of these wells The well survey data is included as Appendix E To meet the survey objective, the following tasks were performed ' • Geological Technics Inc personnel reconnoitered the site on January 5, 2001 to make a physical search for any wells in the area • Specific well logs were requested from the State of California Department of Water Resources (DWR) both to aid in identifying local wells and to specify their construction details The DWR well logs that were available for this area are included in Appendix E • Mr Eric Mar of the California Water Services Company was contacted regarding municipal wells serving the area Forty active wells were located within the 2,000-foot radius search area The commercial, ' industrial and residential properties in the area are serviced by private domestic wells Some industrial facilities within the subject area are serviced by the CWSC Well details are shown in Table 1, Appendix E and the approximate well positions are plotted on Map 1, Appendix E A designation for the beneficial use of groundwater in the vicinity of the Marci Property facility as domestic supply is appropriate based on the results of the receptor survey outlined above ' 2.8 Potential Effects of Residual Contamination The contamination described in Section 2 0 will persist in the environment if left in place When petroleum hydrocarbons are released to the soil, the material moves deeper under the primary influences of gravity, groundwater flow patterns, and capillary action As the product reaches the water table it concentrates on the top of the groundwater surface due to ' its lesser density Petroleum constituents then dissolve from the pool into the groundwater to form a contaminant plume that migrates under the control-of the groundwater gradient At the same time the m dissolved plue is forming and mirating, non-dissolved petroleum ' product remains in the pore spaces in the soil due to capillary forces These forces make it difficult to remove the non-aqueous phase liquids (NAPL) trapped in the pore spaces Fresh water moving through the soil can eventually flush a portion of the NAPL out, but this process can take a very long time and can contribute to an extensive groundwater plume At this time the plume does not appear to have mmgrated off site in the 17 years that has ' elapsed since the USTs were removed in 1987 If a seepage velocity is calculated for the site, a contaminant transport velocity can be derived 1