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GedogicalTecknicslnc. Page 4 Additional Site Characterization i And V Quarter 2004 Groundwater Monitoring Project No.425.2 � March 22,2004 � Benzene, toluene, ethylbenzene and xylene (BTEX) by EPA method 8020 . * Gasoline range petroleum hydrocarbons (TPH-Gasoline) by EPA method 8015(m) • Fuel Oxygenates by EPA method 8260 ❑ MtBE, ETBE, TAME, DIPE and TBA 1 The detection limits for these compounds are listed in the laboratory data sheets included in Appendix B and summarized in Table 2 of Appendix A. A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity. The laboratory data was submitted electronically to GeoTracker as required under AB2886 t �• on November 6, 2003. Confirmation numbers are 7732901990 for September 23, 2003 data and 8983619272 for October 21, 2003 data. 2.2 Quarterly Groundwater Monitoring 2.2.1 Groundwater Sampling Procedure Del-Tech Geotechnical Support Service (Del-Tech) personnel were not able to meet the 4`h � Quarter groundwater-monitoring deadline due to the holidays. On January 3, 2004, Del- Tech 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. Floating sheen was observed in MW-2 during this sampling event. 1 � �wyy�4 i Stagnant water in the well casing was purged using a HondaO centrifugal pump in MW-1 t VP through MW-8, MW_102, MW-105 and MW-107. A WaterraC pump and dedicated tubing j was used in the remaining monitoring wells. The rate of well purging was monitored. The well was purged of at least three casing volumes until the groundwater parameters ' (temperature, conductivity and pH) had stabilized (Appendix C) indicating that water 3 representative of actual aquifer conditions was entering the well. Groundwater parameter r 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 its initial level. Because of slow recharge, MW-7, MW-8, and MW-106 recharged to approximately 65% to 72% of their initial level prior to sample collection. All water removed from the monitoring well and not used as a sample was placed in a 55 gallon DOT approved container that is properly labeled and temporarily stored on-site. Samples were collected using a 1-foot stainless steel bailer with stainless steel wire line in MW-1 through MW-8, MW-102, MW-105 and MW-107. A WaterraD pump and dedicated tubing were used to collect each sample in the remaining monitoring wells. Extreme care was exercised while collecting samples to prevent agitation of the water contained in the WaterraO pump. With minimal sample aeration, water samples were transferred from the pump into 40-m1 VOA vials preserved with hydrochloric acid or trisodium phosphate. All samples were checked for headspace bubbles, labeled, inserted into foam holders and placed into a cooled ice chest for transport to the laboratory. r [--, The sampling technician, wore disposable gloves while collecting all samples. L