ARCHIVED REPORTS_XR0008787 - Laserfiche WebLink

Home Browse Search

Mr Harlin Knoll Page 2 of 3 June 19, 2002 and September 4, 2002 A potentiometric surface map is presented on Figure 2 Groundwater monitoring data are summarized in Table 1 Monitoring data sheets are included in Attachment A An experienced Ground Zero technician purged at least three well casing volumes of water from monitoring wells MW through MW4 prior to sampling the wells The technician measured temperature, pH, and electrical conductivity during the purging process The technician collected samples after the physical parameters stabilized and water levels recovered to at least 80% of pre- purged levels Purged groundwater was contained in appropriately labeled DOT-approved 55-gallon drums The drums are currently being stored onsite pending disposal Purge logs are included in Attachment A Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (FLAP 92359) Samples were analyzed for the presence of BTEX, 1,2-DCA, EDB, and oxygenated gasoline additives using EPA method 8260B GROUNDWATER ANALYTICAL RESULTS BTEX continues to be below the laboratory method detection limits (MDL) in all site wells Methyl-tent butyl ether (MTBE) was the only chemical of concern detected at the site MTBE was detected in wells MW1, MW3 and MW4 at 3 0 parts per billion (ppb), 220 ppb and 14 ppb, respectively No MTBE has been detected in well MW2 since sampling began at the site Analytical results are summarized in Table 2 MTBE concentrations over time in site wells are illustrated on Figure 3 Attachment B contains laboratory reports and chain of custody documentation for samples collected during the reporting period SUMMARY AND CONCLUSIONS • Groundwater levels at the site rose an average of 0 39 feet since the last round of sampling The groundwater gradient was approximately 11 feet per mile toward the southwest • TPHg and BTEX have not been detected in any site wells since sampling began at the site • MTBE was the only chemical of concern detected at the site during this round of sampling MTBE concentrations in wells MWl and MW3 decreased, and well MW4 increased slightly since the last sampling event No chemicals of concern were detected in well MW2 • MTBE concentrations were below the secondary Maximum Contaminant Level (MCL) of 5 ppb in wells MWl and MW2 MTBE was above the secondary MCL in wells MW3 (290 ppb) and MW4 (14 ppb) i G 1Data1GROUNDZE1Bamyard-Manser\Reports\QMR13QM2002 doc