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C�eologicalrecluticsljec. Page 3 } . Groundwater Monitoring Report Project No. 723.2 September 30,2002 1.2 Groundwater Sampling Procedure h f ? On June 6, 2002, Del-Tech Geotechnical Support personnel arrived on-site,.,opened the k wells and measured the depth to.water"with an electrically actuated sounding tape. The rt water level readings were recorded to an accuracy of 0.01 feet. In wells.where free-floating ' product is suspected, a clear disposable bailer is used to gauge the interface. During this monitoring no free product was noted. Stagnant water in the well casing was purged using a Waterra-pump as recorded in the field logs (Appendix Q. The rate of well purging was monitored. The wells were purged of j approximately three casing volumes and until the groundwater parameters (temperature, conductivity and pH) had stabilized (Appendix C) indicating that water representative of actual aquifer conditions was entering the well. Groundwater parameter stabilization was .� characterized by three successive readings within 10%. Before a sample was collected, the well's water level was allowed to recharge to at least 80% of the initial level. The purge water was placed in a properly labeled 55-gallon DOT (Department of Transportation 17-H) approved container and temporarily stored on-site. The dedicated Waterra pump was used to collect,each monitoring well sample. Extreme ' care was exercised while-transferring the sample into 40-ml VOA vials preserved with hydrochloric acid. All samples were checked for headspace bubbles, labeled, inserted into �{. foam holders and placed into an ice chest cooled to 4°C for transport to the laboratory. The sampling technician wore disposable gloves while collecting all samples. E 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. 1.3 Laboratory Analyses The groundwater samples collected on June,6, 2002, were delivered to Sherwood Labs of ' Hilmar, California(certification #1400) for analyses of. • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX), MTBE, by EPA method 8020. • Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA method 503018015(M). The detection limits for the above analyses are listed in Table 2 of Appendix A, while the E lab analytical results are presented in Appendix B.