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, i • 23 May 2001 AGE-NC Project No 95-0144 Page 2 of 8 3 monitoring activities Pumping and disposal was completed by Nor Cal Oil, Inc of Denair, California All waste was disposed at Americlean, Inc located in Silver Springs, Nevada A copy of the waste disposal manifest is included in Appendix B The location of the three-stage clarifier is illustrated in Figure 2 22 MONITORING WELL PURGE PROCEDURES , On 28 February 2001, a Solmst water level meter was used to measure the depth to groundwater in ' 15 monitoring wells at the subject site relative to the tops of the well casings The ground water elevations and hydraulic gradient were determined from these data(Table 1) After depth to water measurements were recorded,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 Monitoring was perrformed 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 A All purged water was stored m 55'gallon DOT-approved drums on-site r 2 3 COLLECTION OF GROUND WATER SAMPLES y 4 ' The depth to water was remeasured immediately following purging 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 r EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid 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 McCampbell Analytical,Inc (MAI), a California Department 1 of Health Services (DHS)-certified analytical laboratory Each sample was analyzed for Total petroleum hydrocarbons quantified as gasoline(TPH-g),total petroleum hydrocarbons ' quantified as diesel (TPH-d) and total petroleum. hydrocarbons quantified as motor oil (TPH-mo) in accordance with EPA Methods 5030/8015 and 355018015, respectively, and Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether . (MTBE) in accordance with EPA Method 8020/602 Advanced GeoEnvironmental,Inc