ARCHIVED REPORTS XR0007248 - Laserfiche WebLink

Home Browse Search

GVV'Y' AT C A S S O C I A T E S I N C ' No petroleum constituents have been detected in water samples collected from the on-site domestic well The most recent monitoring well groundwater analytical data indicates that dissolved petroleum hydrocarbons are confined to within ten feet of the former USTs Tlus is based on the fact that no water samples contain analytes above laboratory MDLs and the distance of the nearest monitoring well to ' the former USTs Although the upper strata have been impacted by petroleum hydrocarbons, tlus upper water-bearing zone, overlying clay strata(s) would be expected to act as a physical protection barrier against migrating petroleum contaminants and protects the underlying aquifers Human exposure to residual petroleum affected soil is unlikely unless excavation ' of the soil were to occur The site is capped concrete and asphalt 7_2 Appendix 1B 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 8.0 SUMMARY The distribution of petroleum constituents in soil beneath the site appears to be limited laterally to the immediate vicinity of the former USTs The highest concentrations are present between 15 and 45 feet bgs Petroleum affected soil at this site generally attenuates rapidly with depth and is expected to degrade to nondetectable levels over time Findings of our evaluation concluded that the project site does not appear to represent a significant risk to human health and the environment In the judgment of ATC, NFA as a "low risk, groundwater case site" is appropriate for this site The site's three existing monitoring well should be abandoned in accordance with PHS/EHD guidelines and a once competed, a NFA letter should be issued r W 1148851repoMkNFA-Request doc 14