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0 C 171-8 VL A 8 5 0 C I A T E 5 I N C ANALYTICAL RESULTS 3 The groundwater sa le collected from well MW4 contained detectable concentrations of TPHg, benzene, and ene constituents Groundwater samples collected from wells MWl and MW5 through MWS contained no detectable concentrations of TPHg or BTEX constituents Groundwater samples collected from wells MW 1, MW4, MW5, MW6, and MW8 contained detectable concentrations MTBE ranging from 5 5 parts per billion (ppb) in MW I to 2,700 ppb in well MW8 "The groundwater sample from well MW8 contained a detectable concentration of TAME at 15 ppb MW7 contained no detectable concentrations of MTBE, ETBE, DIPS, TAME, TBA, 1,2-DCA, or EDB 'Analytical results of groundwater samples are summarized in Table 2 Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 'An isoconcentratron map depicting the MTBE concentrations in on-site wells during the first quarter 2004 is shown on Figure CONCLUSIONS Concentrations from wells MW 1 through MW8 generally remain consistent with the results from the previous sampling event The direction of groundwater flow was reversed and with the previous monitoring event The gradient is still very shallow at only 0 0008 ft/ft Groundwater elevations have increased since November 2003 RECOMMENDATIONS Based on the results of the first quarter 2004 monitoring episode, we recommend the following • Conduct the second quarter 2004 groundwater monitoring and sampling of wells MW 1 and MW4 through MWS and analyze samples for TPHg and BTEX by EPA method 8020B and MTBE, ETBE, DIPE, TBA, TAME, 1,2-DCA, and EDB by EPA method 8260B • ATC is preparing a workplan for additional site investigation activities as requested by SJCEHD in their correspondence dated March 8, 2004 , • slenviromenta1125847\00371reportsllgr-2004 doc 4