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F J l 04 April 2001 AGE-NC Project No 95-0144 Page 4 of 9 2 2 5 Boring Abandonment The probe borings were abandoned by backfilling with a neat portland cement grout The cement was I� trermn-ned into boring 1513-10 and was introduced by free fall into the remaining borings A grout inspection was conducted by the PHS-EHD 2 3 MONITORING WELL PURGE PROCEDURES ' On 28 November 2000, a Solinst water level meter was used to measure the depth to ground water in 15 monitoring wells at the subject site relative to the tops of the well casings The ground water ' elevations and hydraulic gradient were deterrruned from these data(Table 1) On 28 November 2000, monitoring wells MW-1, MW-2, MW-4, MW-13, MW-19A, MW-19B, MW-20A, MW-20B, MW-21A and MW-21B were purged using submersible purge pumps Monitonng was performed in accordance with the revised monitoring schedule established at a 03 April 1998 meeting with the PHS-EHD The purge pumps were decontaminated prior to purging ' each well by pumping an Alconox solution followed by pumping tap water Approximately three casing-water volumes of water (approximately eight to eighteen gallons) were removed from each of the,purged wells Temperature, pH and conductivity of purged water were measured at regular ' purge--volume intervals using a Hydac water analyzer The recorded field data and logs are included in Appendix B All purged water was stored on site in 55-gallon DOT-approved drums on-site 2 4 COLLECTION OF GROUND WATER SAMPLES The depth to water was remeasured immediately following purging in each well to gauge the recharge rate and to assure a minimum of 80 percent recharge prior to sampling Water samples were collected from each purged well using new disposable bailers Samples were transferred into 40-m1 iEPA-approved VOA vials containing 0 5 ml 18% hydrochloric acrd as a sample preservative and into 1-liter amber bottles without preservative The samples were labeled, stored on ice and transported under chain-of-custody to McCarnpbell Analytical, Inc (MAT), a California Department of Health Services (DHS)-certified analytical laboratory Each sample was analyzed for • TPH-g, TPH-d and TPH-mo in accordance with EPA Method 8015 modified for each hydrocarbon range, BTEX and methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 8020/602, 1 and • MTBE, TBA, DIPS, ETBE, TAME, EDB and 1,2 DCA by EPA Method 8260 Modified Advanced GeoEnvironmental,Inc