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A S S O C I A T E S 1 N C the investigation, groundwater wells were installed only in the shallowest aquifer. Boring IP-SB2-70 was advanced to a depth of 70 feet bgs. The soil sample collected at this ' depth contained no detectable concentrations. Therefore, the likelihood of pollutants remaining in the aquifer threatening these potential receptors is very low. ' Criterion 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. During the last monitoring event only TPHd and TPHss were present in the groundwater from well MW3, all other constituents were reduced to nondetectable levels. Based on depth to groundwater, limited extent of impacted soil and groundwater, and distance to receptors, the subject site does not appear to represent a significant risk to human health ' and the environment. Human exposure to residual petroleum affected soil is unlikely unless excavation of the ' soil were to occur. Human exposure to the dissolved groundwater plume is unlikely unless an on-site shallow well is used for drinking water purposes. 6,62 Appendix B Check List Appendix B of the Tri-Regional Board's recommendations checklist of required data for site ' closure of USTs has been completed, as appropriate. The checklist is included in this report as Appendix A. ' 7.0 CONCLUSIONSIRECOMMENDATIONS ' Findings of our evaluation concluded that the project site does not appear to represent a significant risk to human health and the environment. Based on the available data, on behalf of Inland Paint, ATC formally requests NFA for this site. ' ATC recommends destroying existing monitoring wells MW1, MW2, MW3, and MW4. Upon concurrence by PHS/EHD with our recommendations,ATC will submit a workplan and permits for monitoring well destruction. w:1172951reportslclosure.due 8