ARCHIVED REPORTS_XR0012018 - Laserfiche WebLink

Home Browse Search

f � I � Ms Rebecca Setliff i Page 3 of 4 • well MW 11 for the first time since sampling began in this well These wells are clearly affected by offsite releases EDB was not detected in any monitoring wells sampled, however, 1,2 DCA was present in momtoring wells MW10, MW 11, and MW 14 at concentrations of 16 ppb, 4 1 ppb and 370 ppb, respectively This is the first time 1,2 DCA has been detected in well MW14 Analytical results for gasoline oxygenates, EDB and 1,2 DCA are summarized in Table 3 Attachment B contains laboratory reports and chain of custody documentation Vapor Extraction Wells I The concentration of TPHg reported in vapor well VW2 was the highest to date, and the concentration of benzene doubled Petroleum hydrocarbon concentrations present in vapor wells VW4 through VW6 were similar to previous results EDB was not detected in any sampled vapor wells 1,2 DCA was detected only in vapor well VW4, at a concentration of 97 ppb No gasoline oxygenates were detected in vapor wells VW4 through VW6 In vapor well VW2, however, MTBE was detected for the first time at a concentration of 490 ppb This is attributed to further encroachment of the plume of contamination emanating from the Top Filling Station located at 101 S Wilson Way • TPHg and BTEX concentrations are summarized in Table 2 1,2 DCA, EDB and gasoline oxygenate additive concentrations are summarized in Table 3 Attachment B contains laboratory reports and chain of custody documentation GROUNDWATER SAMPLING SUMMARY AND DISCUSSION • Water levels fell during this quarter Groundwater elevation data continue to show an easterly groundwater flow direction However, the local gradient near the southern portion of the property had a northerly component • TPHg and BTEX concentrations were generally stable to decreasing, however, in monitoring well MW3 and vapor well VW2 reported TPHg and BTEX concentrations were at their highest levels to date Increases of contamination in these wells appear to be the result of off site plume encroachment • High levels of MTBE persist in the wells located along the southern portion of the property Concentrations in wells MW3 and MW 14 were at the highest levels to date MTBE was detected for the first time in vapor well VW2 at a concentration of 490 ppb MTBE was also detected in well MW 11 for the fii st time The contamination plume originating at the Top Filling Station is continuing to spread and is now commingling with the Knowles Plume Until this event, MTBE was not present in the wells locat,,,, within the area affected by the onsite -i gasoline release roeklgmrl4QME2001