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Page 3 Mr Michael Infuma jr,Senior REHS ' May 11,2001 wells Temperature,pH, and electrical conductivity parameters were also measured during the purging process to assess groundwater stability Purged groundwater was placed in one 55-gallon drum, which is temporarily stored on- site pending proper disposal Groundwater samples were collected from each well with its own dedicated ' bailer The samples were placed in clean, laboratory-provided glass containers, sealed, labeled, and stored in an insulated iced chest The samples were delivered to Acculabs, Inc laboratory in Davis, California, accompanied by chain-of- custody documentation, for chemical analysis Samples were analyzed for BTEX and TPI-Ig compounds using EPA Method 602/8015 Samples were also analyzed for the oxygenate compounds tert-butanol (TBA),methyl-tert-butyl ether (MTBE), di-isopropy ether (DIPE), ethyl-tert-butyl ether(ETBE), and tert- amylmethyl ether (TAME) using EPA Method 8260B ' Groundwater Level Measurements As shown in Table 1 (Attachment 2), groundwater within the monitoring wells were measured at depths approximately 1 feet higher than the previous round of monitoring performed in January 2001 Groundwater depths ranged from 23 46 feet (below the top of the well casing)to 23 94 feet The corresponding groundwater elevations, evaluated during this monitoring period, ranged from minus(-)12 46 feet to—12 67 feet relative to mean sea level As shown in Figure 3, groundwater flows easterly at an approximate gradient of 2 17 x 10- feet per foot, which is consistent with histornc trends rGroundwater Sample Analytical Results Petroleum hydrocarbon concentrations were detected in the groundwater sample collected this quarter from monitoring well MW-2 (see Table 2) Petroleum concentrations were not detected in the samples from MW-1 and MW-3 Petroleum hydrocarbon concentrations in the current MW-2 groundwater sample are lower, but still within an order of magnitude, compared to the initial sample collected from this well in July 1999 Benzene and TPH-g concentrations in the current MW-2 sample were measured at 14,000 micrograms per liter (ugll) and ' 98,000 ug/l, respectively (see Figure 4 and Figure 5) Current toluene, ethylbenzene, and xylenes concentrations in the MW-2 sample are also comparably similar to historic levels 1 r