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r - Page 3 Mr Michael lnf ima Jr,Senior REHS IP November 7,2000 electronic well sounder, checked for potential free phase petroleum product, and then purged a minimum of three well volumes from each well with clean, disposable bailers Free phase petroleum product was not observed in any of the wells Temperature, pH, and electrical conductivity parameters were also measured during the purging process to assess groundwater stability Purged groundwater was placed in 55-gallon drums, which were subsequently removed from the site and properly disposed of Philip also arranged for the disposal of 14 other drums of waste that had been previously generated by GZA rGroundwater 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 TPHg compounds using EPA Method 602/8015 Samples were also analyzed for the oxygenate compounds tert-butanol (TBA), methyl-ter -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 by Kleinfelder at depths approximately 1 foot lower than during previous rounds of monitoring Groundwater depths ranged from 24 10 feet (below the top of the well casing) to 24 80 feet The corresponding groundwater elevations, evaluated during this monitoring period,ranged from minus (-)13 10 feet to--13 53 feet relative to mean sea level As shown in Figure 3, groundwater flows southeasterly at an approximate gradient of 6 97 x 10-3 feet per foot Groundwater Sample Analytical Results BTEX and TPHg concentrations were only detected in the groundwater sample collected this quarter from monitoring well MW-2 Petroleum hydrocarbon r concentrations in the current MW-2 groundwater samples are comparably similar (within an order of magnitude) to the initial sample collected from this well by GZA in July 1999 For example,benzene concentrations decreased from 20,000 micrograms per liter(ug/1) in the July 19, 1999 sample to 15,000 ug/l in the October 12, 2000 sample TPHg increased from 120,000 ug/l in the July 1999 sample to 130,000 ug/1 in the October 2000 sample Toluene, ethylbenzene, and i