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' 24 June 2005 • AGE-NC Project No 98-0534 ' Page 3 of 6 ' 2 2 GROUND WATER MONITORING EVENTS On 28 January 2005, a ground water monitoring and sampling event was performed on eight ' monitoring wells (MW-1 through MW-8) On 17 February 2005 monitoring well MW-9 was sampled after development and on 01 April 2005, monitoring well MW-9 was sampled after an individual monitoring event Ground water monitoring procedures for the site were outlined in Preliminary Site Assessment Work Plan, dated 15 June 1999 and conform to ground water monitoring guidelines issued by the San ' Joaquin County Environmental Health Department (EHD) ' 2 2 1 Monitoring Well Purging and Sampling A Solmst water level meter was used to measure the depth to ground water in monitoring wells ' MW-1 through MW-8 on 28 January 2005 The depth to water was measured for only monitoring well MW-9 on 17 February and on 01 April 2005 lieAfter depth to ground water measurements were taken, a minimum of three casing-water volumes were purged from each well using a new, disposable, dedicated bailer Between 9 and 10 gallons of water were removed from each well Temperature,pH and conductivity of purged groundwater were ' measured at 3 or 3 5 gallon intervals using an Oakton water analyzer Copies of the field data sheets are in Appendix B Purged water was temporarily stored on-site in DOT-approved 55-gallon drums pending proper disposal 2 2 2 Collection And Analysis of Ground Water Samples After depth to ground water was re-measured to ensure that a minimum of 80% well-volume recharge had been achieved, a water sample was collected from each well using the dedicated, disposable plastic bailer Immediately upon retrieval, samples were transferred into a 1-liter amber bottle and three 40-m1 EPA-approved volatile organic analysis(VOA)vials containing 0 5 ml 18% ' hydrochloric acid as a sample preservative The samples were logged on a chain of custody form, then stored in a chilled container under ice The samples were later transported under chain of custody to Cal Tech Environmental Laboratories(CTEL),a State of California Department of Health ' Services (DHS)-certified analytical laboratory, for analysis The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) in ' accordance with EPA Method 8015 Modified, r Advanced GeoEnvironmentel,Inc