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CreolagualTalucres rxtr Page 2 Groundwater Monitoring Report Project No 989 2 August 30,2004 1 ' 1.0 GROUNDWATER MONITORING 1.1 Groundwater Sampling ' On April 28, 2004, 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 had been 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 WaterraO 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% MAll 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 Waters®-style 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 1.2 Laboratory Analyses ' The groundwater samples collected on April 28 2004 weredelivered to Sherwood Labs ' Corporation (ELAP# 1400), of Hilmar, California, for the following analyses • Benzene,toluene, ethylbenzene and total xylenes (BTEX) by EPA method 8020/8015 • Gasoline range petroleum hydrocarbons (TPH-G) by EPA method 8020/8015 • MtBE by EPA method 8021B (positive results confirmed by EPA method 8260) i h