Laserfiche WebLink
occurred due to natural degradation Benzene concentrations in samples <br /> collected from well MW-I, located near the original source of the petroleum <br /> release, have ranged from a high of 6,800 micrograms per liter (µg/L) in July <br /> 1987 to a low of 170 pg/L in October 1998 (see Table 4) Total petroleum <br /> hydrocarbons as gasoline (TPH-G) concentrations in samples from MW-1 <br /> have ranged from a high of 196,000 pg/L in April 1993 to a low of 15,000 <br /> µg/L measured in August 1999 Current petroleum hydrocarbons <br /> concentrations are discussed in Section 3 of this report <br /> Oxygenate compounds methyl tert butyl ether(MTBE), ethyl tert butyl ether <br /> (ETBE), and tert amyl methyl ether(TAME) have never been detected in site <br /> groundwater samples (see Table 5) The oxygenate compound di-isopropyl <br /> ether (DIPE) had historically been measured at concentrations of 100 pg/L or <br /> less in samples collected from wells near the source of the release Momtoring <br /> ' data indicates that the lateral extent of DIPE impact is limited to Earthgrain's <br /> property boundaries The compound tert-butyl ether (TBA) was detected in <br /> one groundwater sample collected from MW-I on November 8, 1999, and <br /> ' again in the PZ-1 sample collected this quarter, but has never been detected in <br /> any other groundwater sample collected at the site <br /> ' As shown in Table 1, the current depth to groundwater averages about 40 feet <br /> below ground surface (bgs) The lowest depth to groundwater, observed <br /> during our historic site monitoring, was about 60 feet bgs in December 1992 <br /> (see Historical Groundwater Elevation Data in Table 2) The PHS/EHD <br /> suggests that groundwater was at a depth of about 80 feet in 1978 <br /> Groundwater has consistently been evaluated to flow in an east-northeast <br /> direction at approximately N70E across the site Current groundwater <br /> elevation information is contained in Section 3 1 <br /> 1 <br /> 6 <br /> October 2000 <br /> Groundwater Monitoring Report <br /> The Earthgrains Company <br /> 2651 South Airport Way <br /> Stockton,California <br /> prepared for THE EARTHGRA[NS COMPANY Prepared by Philip Services Corp <br /> H%NVW24001725121382EG\Stockton\Stockton11000mon dm November 10,2000 <br />