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5.0 POTENTIAL RECEPTORS Figure 26 is map of the site area showing the locations of near-surface utility lines, primarily water and sewer Imes These utilities are usually burled at shallow depths (generally 5-10 feet), and have therefore been above the saturated zone since groundwater morutormg began at this site Should the groundwater level rise to less than 10 feet at some time in the future, it is conceivable that groundwater could enter the utility trenches However, the water and sewer lines along Acacia Street are both upgradient of the site, and it is therefore unlikely that these lines could become contaminated (the upgradient monitor well, MW-3, has only rarely contained detectable concentrations of hydrocarbons) Utility lines on the west side of Yosemite Street have probably never been contaminated, because no contan-unants have ever been detected in MW-6 and concentrations have been low and/or declining in MW-1 and MW-5 The only potential near-source receptor might be the house directly north of the site Upgradient reviewed the water well files at the California Department of Water Resources in Sacramento Table 5 lists four wells that have been drilled within approximately 2000 feet from the site The wells are also shown on the map in Figure 27 It is unlikely that any of them could be impacted by migration from the Conrady site for three reasons 1)they are all quite far away, 2) the plume appears to be shrinking rather than migrating, and 3) the one well that is located downgradient of the site was abandoned in 1967 Two surface water bodies are also located within 2000 feet of the site (Figure 27) However, the Stockton Deep Water Ship Channel is upgradient of the site, and Yosemite Lake is more than 1700 feet downgradient The groundwater plume would certainly be diluted to non- detectable levels long before it could reach the lake Based on our review, we consider the potential risk to groundwater receptors to be very small 6.0 NO FURTHER ACTION Appendix B of the Tri-Regional Recommendations specifies four conditions that must be met in order to designate a site as a low-risk groundwater case 1) Contaminants remaining in the vadose zone must not reverse or threaten to reverse the mass reduction rate of groundwater pollutants 2)Separate phase product has been removed to the extent practicable 3)No existing water supply wells, deeper aquifers, surface waters or other receptors are threatened by pollutants remaining in the aquifer 4) The total pollutant mass remaining in the groundwater is decreasing at predicted rates and neither creates, nor threatens to create, a risk to human health and safety or future beneficial use(s) of the aquifer 9