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Mr Ron Rowe Page 3 of 5 Wells MW3 and MW4 are located along the southern boundary of the subject property and are Wes a � rY J p p Y affected by offsite release(s) MW7, located slightly north of MW3, is now apparently also ' affected Hydrocarbon concentrations in MW3 continued to increase and the concentrations in MW4 remained very high Levels of TPHg and BTEX decreased in well MW7 following one ' round of moderate concentrations However, MTBE was present for the second consecutive quarter TPHg and BTEX concentrations are summarized in Table 2 ' Samples from wells MW1 through MW10, and MW13 were also analyzed for oxygenates Oxygenates were not detected in the samples from wells MWi, MW2, MW6, MW8, MW10, and MW 13 (wells MW 11 and MW 12 were inaccessible) MTBE was detected in samples from wells ' MW3 and MW4 at concentrations of 4,000 and 3,100 parts per billion (ppb), respectively and in samples from MW7 and MW9 at levels of 20 and 22 ppb, respectively The source of MTBE in each of these wells 1s believed to be offsite releases DIPS was detected in well MW5 at a ' concentration of 30 ppb DIPE, TBA, ETBE and TAME were not detected in any of the samples collected from the other groundwater wells Oxygenate concentrations are summarized in Table 3 ' Vapor Extraction Wells Groundwater samples were collected from vapor wells VW 1 and VW3 through VW6 (VW2 was dry) Petroleum hydrocarbons were detected in groundwater samples collected from the vapor extraction wells The highest concentrations of TPHg and BTEX were detected in water samples collected from well VW1 and showed an mciease since the previous sampling in February, 1998 Concentrations of TPHg and BTEX in the water sample collected from well VW4 also increased ' since February 1998 It should be noted that the VES never operated on VW l or VW4 because the screens in those wells have been submerged since the inception of vapor extraction Concentrations of TPHg and BTEX in VW3 have declined since the well was last sampled in ' February 1998 TPHg and BTEX were present at low concentrations in the sample from VW5 (first sampling event for this well) Concentrations of TPHg and BTEX decreased dramatically in t water samples collected from VW6 since the well was last sampled in February 1998 TPHg and BTEX concentrations are summarized in Table 2 ' Samples from vapor extraction wells VW I and VW3 through VW6 were also analyzed for oxygenates TBA was detected in the sample collected from vapor well VW 1 at a concentration of 670 ppb and DIPE was detected in VW4 at 20 ppb Other than these, no oxygenates were ' detected in samples collected from the vapor extraction wells Oxygenate concentrations are summarized in Table 3 ' Groundwater Sampling Summary and Discussion MTBE was detected in well MW4 for the tenth consecutive quarter MTBE was also detected in well MW3, located downgradient of MW4, for the eighth consecutive quarter, at the highest concentration to date TPHg and BTEX concenti ations also remained high in MW4 during this roeklgmrl i gm2000