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collected from well MW_I, Iocated near the original source of <br /> release, have ranged from a high of 6,800 micro r the petroleum <br /> 1987 to a low of 170 µg/ in October 1998 {see Table per <br /> liter <br /> hydrocarbons as gasoline In <br /> {1 ig�-) in July <br /> ( G) concentrations in samples fromtMW� <br /> have ranged from a high of 196,000 µg/L in April 1993 to a <br /> ugh. measured in August 1999 C low of 15,000 <br /> concentrations are discussed in Section 3 of this report <br /> Oxygenate <br /> Oxygenate compounds methyl tert butyl ether <br /> (ETBE), and tei-t amyl methyl ether TA (MTBE) ethyl tei-t butyl ether <br /> s (see Table S (TAME) have never been detected In site <br /> groundwater sample <br /> ether(DIPE) had historically been measured at concene Oxygenate tration, di-isopropyl <br /> less in samples collected from wells near trateons of 140 PL <br /> data indicates that the lateral extentthe source of the release Mo g/I or <br /> of DIPE impact is limited to Earthgra n'Sg <br /> Property boundaries The compound tert-butyl ether <br /> one groundwater sample collected from (TBA) was detected in <br /> again in PZ_1 samples collected on October g 204 November 8, 1999, and <br /> has never been detected in any other groundwater sale le and <br /> April 20, 2001, but <br /> As shown p collected at the site <br /> wn in Table 1 and Table 2, recent depths to groundwater averages <br /> about 40 feet below ground surface (b $ <br /> observed durin our g ) The lowest depth to groundwater, <br /> g historic site monitoring, <br /> December 1992 The PHS/EHD was about 60 feet bgs in <br /> suggests about 80 feet in 1978 Groundwater ghas tcons consiat stently been evaluated dwater as at a depth of <br /> an east-northeast direction at approximately N70E across theto flow in <br /> groundwater elevation information Current site <br /> is summarized in Section 3 1 <br /> r1.4 Remedial Action <br /> On April 25, 2001, PSC initiated operation of an air spar in <br /> remediation system to address subsurface petroleum hydrocarbon <br /> described in PSC's Au g g and soil venting <br /> performed b gust 3 I, 2000 Rem Work Flan siripact As <br /> y supplying an approximate volume of 10 standard cube feet g is <br /> per <br /> minute (scfm)of air to weII SP-I Venting is performed b <br /> approximate volume of 20 to 25 scfm of soil gas from well V W,1 p <br />' treated Inditlally <br /> through a prima y withdrawing an <br /> ' 1,000 pound granular activated carbon gas is <br /> (GAC) sorber and then through a secondary 160 pound GA <br /> Permits to operate the remediation system and em C adsorber <br /> Obtained from the San Joaquin Air Pollution Control District (S <br /> have been <br /> JAPCD) <br /> Emission reports are routinely submitted to the SJAPCD <br />` 6 <br /> July 2001 <br /> Groundwater Monitoring and <br /> Rernedtal Action Results <br /> The Earthgrarns Company <br /> 2651 South Airport Way <br /> prepared for T'HE EARTHGRAtNS COMPANY SIockton,California <br /> H\ENV1624g0132112]382EG1Stocktonl5tocktoaW701 moe clot <br /> Prepared by Phtlrp Services Corp <br /> August W,2001 <br />