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(5) Upgradient also concluded that no significant risk to human health and safety existed oris <br /> anticipated to exist in the future. A sensitive receptor survey was conducted and the <br /> nearest potential receptor was identified as ST&E's own well, which is approximately <br /> 300 feet west of the former UST location. The ST&E locomotive shop parcel is several <br /> acres in size, and is surrounded on all sides by.even larger industrial properties and the <br /> ST&E freight yard'. The area is not zoned for residential use. Upgradient concluded that <br /> the risk of public exposure is very low." Upgradient therefore concluded that the residual <br /> diesel contamination within the UST excavation posed no significant threat to public <br /> health (Upgradient, 1999). <br /> Upgradient(1999) recommended site closure but that request was denied jointly by the <br /> California Regional Water Quality Control Board (RWQCB) and PHSEHD (Appendix 1). <br /> Fate and Transport Model''' Upgradient subsequently submitted a fate and transport model for <br /> E hydrocarbon contamination to PHSEHD in 2001 (Upgradient, 200 1) in an attempt to justify site <br /> closure. The results of this transport model suggested that impact to groundwater at depths of 40 <br /> I <br /> to 45 feet bgs might likely occur within several years of the release (1980's). The data contained <br /> f in the report actually suggested a groundwater problem likely existed. However, the Upgradient <br /> document concluded that actual field conditions were not coincident to modeled conditions <br /> (Upgradient, 1999). <br /> On September 20, 2007 PHSEHD directed ST&E to conduct additional site assessment activity <br /> to include collection of soil and groundwater grab samples at the site-to evaluate potential <br /> possible closure of the site. <br /> Stephen G. Muir Consulting Geologist and Geophysicist was retained by ST&E during October r <br /> 2007 to complete the site assessment work required by PHSEHD. A workplan was submitted to <br /> i PHSEHD (Muir, 2007) which was approved during December, 2007. <br /> Environmental\STETA RSCR09102008.wpd 10 <br /> SII <br /> f <br />