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' 03 October 2001 • AGE-NC Project No. 95-0100 ' Page 3 of 6 • Volatile aromatic hydrocarbons-benzene,toluene, ethylbenzene and total xylenes (BTEX) ' and methyl tertiary-butyl ether(MTBE)in accordance with EPA Method 8020. 2.5. MONITORING WELL DEVELOPMENT ACTIVITIES ' On 15 June 2001,monitoring wells MW-4, MW-5 and MW-6 were developed utilizing a stainless steel hand bailer and Grundfos Redi-flow submersible pump. Ground water was purged from monitoring wells MW-5 and MW-6 until ground water was visually sediment free and approximately 8 gallons of water were removed from MW-4 before it was pumped dry. Approximately 34 gallons of water were removed from MW-5 and 30 gallons of water were removed from MW-6. Purged ground water was containerized in properly labeled DOT-approved model 17H 55-gallon drums and was stored on-site. Field sheets and data are included in Appendix B ' 2.6. WELL HEAD SURVEY On 05 September 2001, a California state-licensed survey engineer from Baumbach & Piazza surveyed the elevation of a reference point on the top of ground water monitoring wells MW-4, MW-5 and MW-6 to the nearest 0.01-foot relative to San Joaquin County Bench Mark Datum BM #AABB-42 at 120.526 feet above mean sea level (msl). The results of the monitoring well ' survey are contained in Table 1. The surveying report (Baumbach & Piazza) is presented in Appendix C. 2.7. MONITORING WELL PURGE PROCEDURES 1 Depths to ground water were measured in each well from the tops of the well casings to the nearest 0.01-foot utilizing a Solinst water level meter. Ground water elevation in each well at the site was ' calculated by subtracting the measured depths to ground water from the surveyed casing elevations (Table 1). Ground water elevations were plotted and contoured on a scaled site map (Figure 3). ' On 03 July 2001, after water levels were measured, approximately 5 to 6 gallons of ground water (a minimum of three casing-water volumes per well) were removed from wells MW-1, MW-2, MW-3, MW-5 and MW-6 and approximately 9 gallons of ground water were removed from well MW4-before the well was pumped dry, utilizing-a new disposable plastic bailer at-each wellz On- - _ •--_ 16 July 2001 well MW-4 was re-purged, approximately 10 gallons of ground water were removed utilizing a new disposable plastic bailer. Temperature, pH and conductivity were measured for ' stabilization at regular purge-volume intervals from each well using Hydac or Oakton water analyzers. Field data and logs are in Appendix D. Purged ground water was containerized in DOT-approved model 17H 55-gallon drums and stored at-the site. 1 Advanced GeoEnvironmental,Inc.