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30 July 1999 <br /> AGE-NC Project No 95-0143 <br />' Page 4 of 8 <br /> 2 7 MONITORING WELL PURGE PROCEDURES <br />' On 04 <br /> May 1999, a Solinst water level meter was used to measure the depth to ground water in rune <br />' monitoring wells at the site and ten monitoring wells at the Madison site relative to the tops of the <br /> well casings An Ullage interface probe was used to check for the presence of free product in MW-3 <br /> and VW1 through VW5 The ground water elevations and hydraulic gradient were determined from <br />' these data(Table 3) <br /> On 05 May 1999, each monitonng well at the site was purged using a two-stage submersible purge <br />' pump The pump was decontaminated prior to purging each well using an Alconox solution and <br /> clean tap water Temperature, pH and conductivity of purged water were measured at regular <br /> intervals during purging using an ICM model 52200 water analyzer Dissolved oxygen was <br />' measured in the final purge water using a YSI model 55 dissolved oxygen meter Approximately ten <br /> to fifteen gallons of water were removed from each well except MW-9, from which sixty gallons of <br />' water were purged (approximately three well volumes) All purged water was stored in 55-gallon <br /> DOT-approved drums on-site Field data and field logs are included in Appendix D <br /> 2 8 COLLECTION OF GROUND WATER SAMPLES <br />' The depth to water was remeasured in each well to assure a minimum of 80% recharge prior to <br /> sampling Water samples were collected from each purged well using new, disposable bailers and, <br /> upon retrieval, were transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml 18% <br />' hydrochloric acid as a sample preservative The samples were labeled and transported under chain- <br /> of-custody, in a chilled container, to MAI and were analyzed for <br />' - TPH-g in accordance with EPA Method 5030/8015 <br /> BTEX with MTBE in accordance with EPA Method 602, and <br />' - Oxygenates (di-isopropyl ether [DIPE], ethyl tertiary-butyl ether [ETBE], MTBE, tertiary- <br /> amyl methyl ether [TAME] and tertiary butanol [TBA]) in accordance with EPA Method <br />' 8260 <br />' 29 SURVEYING <br /> On 14 June 1999, the casing elevations of the nine monitoring wells and vapor wells VW1 through <br /> VW5 were surveyed to the nearest 0 01-foot relative to mean sea level as established at a City of <br /> Stockton Bench Mark (Table 3) The revised casing elevations for the nine monitoring wells were <br />' Advanced GeoEmironmental,Inc <br />