ARCHIVED REPORTS XR0011901 - Laserfiche WebLink

Home Browse Search

CvvATC A S S O C I A T E S I N C calculated to be 0.002 ft/ft or about 11 feet/mile. The data indicates a groundwater gradient that is generally consistent with previous groundwater gradients observed at the site. A summary of groundwater monitoring data is presented in Table 1. Groundwater elevations are referenced to feet above mean sea level. Groundwater samples were collected from monitoring wells MW-1 through MW-6. Prior to collection of groundwater samples a minimum of three well casing volumes were purged. The depth-to-water, pH, electrical conductivity, and temperature were measured and allowed to stabilize before groundwater samples were collected. Samples were then collected from each well using disposable bailers. Purge water was contained in 55-gallon DOT approved drums. Purge water from monitoring wells MW-1 and MW-6 from the previous sampling event did not contain detectable concentrations of petroleum hydrocarbons and was discharged to the ground surface. Groundwater well purge and sample logs are provided in Appendix A. The groundwater samples collected from each well were submitted with Chain of Custody Record to State-certified Argon Laboratories Inc. (FLAP Cert. No. 2358). The samples were analyzed for TPHg by EPA method 8015; BTEX by EPA method 8020; and MTBE, ethyl tertiary butyl ether (ETBE), di-isopropyl ether (DIPE), tertiary butyl alcohol (TBA), and tertiary amyl ether (TAME) by EPA method 8260. Groundwater analytical results are summarized in Table 2. The laboratory analytical reports are included in Appendix B. L RESULTS OF LABORATORY ANALYSES Results of the laboratory analysis of groundwater samples from the monitoring wells indicate the presence of petroleum hydrocarbons in groundwater samples from monitoring wells MW-2 and MW-3. No petroleum hydrocarbons were detected in monitoring wells MW-1, MW-4, MW-5, and MW-6. MTBE was detected in well MW-2 at 7.0 parts per billion. The analytical results are summarized in Table 2. CONCLUSIONS AND RECOMMENDATIONS Results of the most recent monitoring event indicate that the concentrations of petroleum hydrocarbons in the groundwater have generally remained the same as the last monitoring event. The groundwater gradient direction has also remained the same. Based on the stability of the plume and the previous closure request report, ATC requests reconsideration of this site for closure. wA17861kepoAs\4gmr1998.doc 3