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Geological rechx1cs Inc. Page 3 Receptor Survey Report Project No. 989.2 October 15,2002 A map showing the locations of DWR reviewed wells, inspected during the receptor survey, is included as Figure 2. Well logs provided by the Department of Water Resources are included in Appendix A. 2.0 OBSERVATIONS & CONCLUSIONS ' Based on our interpretation of the data collected over the course of this sensitive receptor survey, GTI has reached several conclusions. These conclusions are based on the premise that the data gathered are accurate and complete. We acknowledge that there may be undiscovered conditions and information, which upon consideration may change our ' interpretation and thus our conclusions. Observations ' • In general, groundwater flows a northwesterly direction and has an average slope of 0.0062 ft/ft, as calculated from the monitoring well data gathered at the Valley Wholesale Drug Company site. • The Stockton Deep Water Channel and the Mormon Slough are receptors located between 500 and 2000 feet of the site. Monitoring wells listed by DWR as being within the 2000-foot radius could not be located and no evidence of emplacement was found. • Site specific monitoring wells are located on and off the subject property and construction details are included as Table 3. a No evidence of domestic wells was uncovered during the investigation. • No evidence of industrial production wells or municipal water wells was observed ' during the receptor investigation. • Review of DWR records indicates former domestic wells had an average depth of between 140 and 570 feet below grade. ' . DWR reviewed documentation shows an irrigation well in the general area at a depth of 215 feet below grade. ' • CWSC records indicate there are no municipal supply wells within the search area. Conclusions ' • The domestic water supply in the search area comes from the municipal water supply and not from domestic wells. It is not likely that contamination from the Valley Wholesale Drug Company site would impact domestic water supplies. ' • Domestic and irrigation wells formerly or currently located in the area are at such a depth and distance that impact from plume migration is unlikely. • Groundwater monitoring at the site indicates the contaminants are moving away from ' the Stockton Deep Water Channel and the Mormon Slough. Impact to these receptors from the site appears unlikely. I