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i <br /> 8.0 CONCLUSIONS AND RECOMMENDATIONS <br /> i <br /> Ground Zero recommends that the case be closed with no further action required qired based upon the <br /> following: <br /> 1 <br /> * The lateral and vertical extent of soil contamination has been defined. Soil contamination is <br /> e <br /> confined to an area of approximately 700 square feet within close proximity to the former UST <br />. ' location. Soil contamination occurs between the depths of approximately 17.5 and 32.5 feet <br /> below grade. The contaminant consists of highly weathered gasoline range hydrocarbons <br /> ' depleted in BTEX . <br /> • Since the installation of MW1 in May 1995, groundwater levels have risen into the zone of <br /> 1 residual soil contamination. However, no groundwater impact from the residual soil <br /> contamination has been identified either in well MW 1 or in hydropunch boring HP4. The <br /> results obtained from HP4 are considered to represent the worst case due to the abnormally high <br /> ' water levels present during sampling. <br /> • The positive results obtained in the groundwater sample collected from HPI are almost certainly <br /> due to encroachment from an off-site source such as the massive release at 601 E. Miner as is <br /> ' the presence of MTBE in water samples from MW 1. <br /> i ' • The residual soil contamination poses no significant risk to human health or the environment <br /> and no significant threat to groundwater. <br /> An "Appendix B Checklist" and chronology of corrective actions is included in Attachment E. <br /> Please contact Ground Zero at your earliest convenience if you have any questions or comments <br /> regarding this report <br /> 1 Respectfully, <br /> Gro ero Anal s, I <br /> zo <br /> Sean Garvey, <br /> GREGORY P. <br /> ' S logist STAHL <br /> �` No. 5023 <br /> 1 ' <br /> CA Registered hGeolo Geologist No. 5023 ? ,or CAt SE, <br /> g <br /> ' Attachments <br /> cc: Mr. Mark List, RWQCB <br /> ' Mr. Pat Riddle, Esq. <br /> Fred D. and Mary Clarke, et. al. c/o Paul Balestracci, Esq. <br /> lbMs. Janice Magdich, Esq. <br /> ' datalgmundzelva1]eyvwlsummary.doc 7 <br />