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Geological Technics Inc Page 3 Groundwater Monitoring Report Project No. 723.2 March 10,2003 1.2 Groundwater Sampling Procedure f On December 17, 2002, Del-Tech Geotechnical Support personnel arrived on-site, opened the wells and measured the depth to water with an-electrically actuated sounding tape. The 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 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. r , The dedicated Waterra pump was used to collect each monitoring well sample. Extreme care was exercised while transferring the sample into 40-m1 VOA vials preserved with hydrochloric acid. All samples were checked for headspace bubbles, labeled, inserted into i foam holders and placed into an ice chest cooled to 4°C for transport to the laboratory. i 1 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. i 1.3 Laboratory Analyses k The groundwater samples collected on December 12, 2002, were delivered to Sherwood € Labs of Hilmar, California (certification#1400) for analyses of: I • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX), MTBE, by EPA method 8020. • Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA method 5030/8015(M). h Sherwood forwarded well MW-201 samples to Entech Analytical Labs Inc. (Department of 4 Health Services Certification No. 2346) of Santa Clara, California, for analysis of: t k