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!� f v o , A S S O C I A T E S I N C SAMPLING ACTIVITIES On December 4, 2002, ATC personnel collected groundwater samples from monitoring wells MW 1, MW3 through MW 10 At the direction of Mr Nuell Henderson of SJCEHD, groundwater samples were also collected from piezometers AS-1(d), PZ-la(d) and PZ-lb(d), and the on-site groundwater supply well DW A groundwater sample was not collected from well MW2 because of the presence of free product in the well The locations of the wells are shown on Figure 2 Prior to collection of groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in the monitoring wells and recorded A minimum of three well casing volumes were purged from each monitoring well prior to sampling The wells were allowed to recover and samples were collected from each well using dedicated disposable bailers After the groundwater samples were collected, dissolved oxygen was measured in each well The groundwater samples collected from each well were submitted to Argon Laboratories Inc (ELAP Cert No 2359), a state-certified analytical laboratory in Ceres, California for chemical analysis of TPHg utilizing EPA method 8015 modified, benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing EPA method 8020, and methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), di-isopropyl ether (DIPE), tertiary amyl ether (TAME), tertiary butyl ether (TBA), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) utilizing EPA • method 8260 Groundwater well purge and sample logs are contained in Attachment 1 ANALYTICAL RESULTS Groundwater samples collected from wells MW1, MW3, MW6 and piezometers AS-1(d), PZ- la(d), and PZ-lb(d) contained the highest concentrations of TPHg and BTEX Groundwater samples collected from wells MW4, MW7, MW8, and MW 10 also contained detectable concentrations of TPHg and BTEX constituents Detectable concentrations of TPHg ranged from 400,000 parts per billion (ppb) in piezometers PZ-la(d) to 62 ppb in well MW10 Detectable concentrations of benzene ranged from 47,000 ppb in piezometers AS-l(d) to 10 ppb in well MW4 "The groundwater sample collected from wells MW5 and MW9 contained no detectable concentrations of TPHg or BTEX Groundwater samples collected from wells MW1, MW3 through MW 10 and piezometers AS-1(d), PZ-1 a(d), and PZ-1 b(d) contained no detectable concentrations of oxygenate fuel additives although many of the reporting limits were elevated due to dilution The groundwater sample collected from on-site supply well DW labeled influent water contained detectable concentrations of TPHg and BTEX, but contained no detectable concentrations of oxygenate fuel additives Analytical results of groundwater samples are summarized in Table 2 Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 GROUNDWATER FLOW DIRECTION Water level measurements were collected from wells MW 1 through MW 10, AS-1(d), PZ-1 a(d), and PZ-lb(d) on December 4, 2002 Water levels in the shallow aquifer ranged from 67 79 to w\I 63931qua01y\4gr-2002 doc 3