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GROUNDWATER ASSESSMENT REPORT TP-13 were collected from 26 to 30 feet bgs after two faded attempts to intersect water-bearing sediments at 21 feet bgs and 16 feet bgs, respectively Additional groundwater samples were collected at 35 feet bgs from borings TP-10,TP-14,TP-15, and TP-16 to ascertain the potential vertical extent of MTBE in groundwater At these locations, the"Hydro-punch"sampling tool was driven into the groundwater-bearing zone from 31 to 35 feet bgs Groundwater was not encountered in bonng TP-14 at 35 feet bgs,therefore no sample was collected Proposed borings TP-6,TP-7,TP-8, and TP-I I were not accessible to sampling equipment dunng the fieldwork due to saturated soil conditions caused by heavy rain Laboratory analytical results of groundwater samples are summarized in Table 3 Six soil borings (TP-lA,TP-4A,TP-5A,TP-10, TP-14, and TP-15) were drilled in and immediately surrounding the former UST excavation to sample soil for analysts of total lead This was completed during this assessment at the request of the SJCEHD since prior soil sampling and analyses did not include analysis of lead At these locations, a soil sample was collected from the borings at 14 feet bgs, a depth directly beneath the former UST Soil lithology was not logged during the January 2001 assessment but is similar to the subsurface lithology logged during ESA's initial assessment in July 2000 These boring logs are attached to this report as Appendix B ESA field personnel did not detect petroleum odors or hydrocarbon sheen on the water samples Y p Table 3 summarizes the analytical results of petroleum compounds detected in soil and groundwater samples Three groundwater samples were analyzed for the presence of TPH as gas and BTEX by EPA Methods 8015 and 8020 Twelve groundwater samples were analyzed for the presence of MTBE,DIPE, TAME, ETBE, EDB, 1,2-Dichloroethane (1,2-DCA),TBA, ethanol, and methanol by EPA Method 8260 Laboratory analyses did not detect concentrations above the laboratory detection linuts for the constituents analyzed Analyses detected lead by EPA Method 6010 between 5 9 mg/kg and 8 8 mg/kg, which are indicative of naturally-occurring lead concentrations in soils and do not indicate contamination from the petroleum additive tetraethyl lead Laboratory analytical reports are provided in Appendix C IV. GROUNDWATER MONITORING AND SAMPLING Following the review of the January 2001 groundwater assessment findings, in April 2001, the SJCEHD requested installation of three groundwater monitoring wells to establish groundwater flow direction In addition, SJCEHD requested that groundwater samples be collected and analyzed for MTBE for a minimum of four quarters The SJCEHD also noted that in order for this site to be considered for closure, groundwater samples must be collected from all wells and analyzed at least once for total TPH as gasoline, BTEX, five fuel oxygenates, and 1,2-DCE and _ - EDB-_ - ESA submitted the Groundwater Monitoring Well Installation Workplan to SJCEHD on September 27, 2001 for review Ms Dot Lofstrom of SJCEHD approved the workplan on October 1, 2001 The workplan addressed installation of four groundwater monitoring wells to deternune groundwater flow direction and to further delineate the lateral extent of MTBE t Groundwater Assessment Report 10 ESA/200252 September 2003