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Mr Harlin Knoll <br /> October 15, 2001 <br /> Page 2 of 3 <br /> Prior to sampling, monitoring wells MW 1 through MW4 were purged of a minimum of three well <br /> casing volumes During the purging process the physical parameters of temperature, pH and electrical <br /> conductivity were measured <br /> Samples were collected after the physical parameters had stabilized and water levels had recovered at <br /> least 80% from pre-purged levels Purge water was contained in appropriately labeled DOT-approved <br /> 55-gallon drums The drums are currently being stored onsite Purge logs are included in Attachment <br /> A <br /> Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (FLAP <br /> #2359) Samples were analyzed for the presence of TPHg and TPHd using modified EPA method <br /> 8015M, BTEX using EPA method 8020, and oxygenated gasoline additives, 1,2-DCA, and EDB using <br /> EPA method 8260B <br /> GROUNDWATER ANALYTICAL RESULTS <br /> Methyl tert butyl ether (MTBE) was the only chemical of concern detected at the site MTBE was <br /> detected in wells MW1 and MW3 at 8 2 parts per billion (ppb) and 180 parts ppb, respectively <br /> Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain <br /> of custody documentation <br /> SUMMARY <br /> • Groundwater levels at the site rose an average of 0 41 feet since the last round of sampling, and <br /> groundwater flow remained toward the southwest <br /> • Petroleum hydrocarbon constituents, with the exception of MTBE, remained below the laboratory <br /> detection limits <br /> • MTBE was detected only in wells MW 1 and MW3 MTBE levels in wells MW l, MW3 and MW4 <br /> decreased by 86%, 44%, and 98%, respectively since the wells were first sampled in May 2001 <br /> MTBE remained below the detection limit in well MW2 <br /> CONCLUSIONS <br /> MTBE was the only constituent of concern detected at the site, and levels were considerably reduced <br /> since the initial sampling in May 2001 Previous remedial work conducted at the site appears to <br /> have been successful in eliminating the contaminant source Soil and groundwater analytical <br /> .� results suggest that no significant amounts of petroleum hydrocarbons are present in the vicinity <br /> of the former USTs However, groundwater in the well directly downgradient of the former <br /> USTs contained MTBE at a level exceeding the drinking water standard (13 ppb) established by <br /> 6amyard/reporlslymr/3 Q M2001 <br />