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G0010gical Tahnics Inc. Page 2 Groundwater Monitoring Report ' Project No. 989.2 March 12,2004 concentration has decreased significantly in the past seven years of monitoring (Chart 1). A j plot of MtBE concentrations versus groundwater elevation for MW-6 indicates that the concentrations of MtBE fluctuate with groundwater elevation and that the overall MtBE ' concentration has decreased over time (Chart 2). ' LO GROUNDWATER MONITORING ' 1.1 Groundwater Sampling On November 25, 2003, Del-Tech Geotechnical Support Service personnel arrived on-site, opened the wells and measured the depth to water with an electrically actuated sounding tape. The water level reading was recorded to an accuracy of 0.01 foot. If free-floating product was suspected, a clear disposable bailer would have been used to gauge the ' interface. No floating product was observed during this sampling event. Stagnant water in the well casing was purged using a Waterra pump (MW-1 through MW-6 ' and MW-101) and a centrifugal pump (MW-7 through MW-9) with dedicated tubing. The rate of well purging was monitored. The wells were purged of at least three casing volumes and until the groundwater parameters (temperature, conductivity and pH) had stabilized (Appendix B) indicating that water representative of actual aquifer conditions was entering the well. Groundwater parameter stabilization was characterized by three successive readings within 10%. ' All water removed from the monitoring well and not used as a sample was placed into a 55- gallon DOT approved container that was properly labeled and temporarily stored on-site. ' The groundwater samples were obtained utilizing a Waterra foot valve and dedicated ' tubing. Extreme care was exercised while collecting samples to prevent agitation of the water moving in the tubing. Water samples were transferred from the tubing into 40-m1 VOA vials, preserved with hydrochloric acid, while minimizing sample aeration during transfer of the sample. All samples were checked for headspace bubbles, labeled, inserted ' into foam holders and placed into a cooled ice chest for transport to the laboratory. ' The sampling technician wore disposable gloves while collecting all samples. A chain of custody document, listing all samples collected and their intended analyses, ' accompanied the samples from the field to the laboratory, thereby providing a means to track the movement of the samples and ensure their integrity.