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, ' 2-7,Au 2004 .. • AGE-NC Project No. 98-0440' ; ' Page 3 of 6 2.5•, MONITORING WELL'DEVELOPMENT AND SURVEY On 23 March 2004,monitoring wells MW I 1 and MW 12 were developed utilizing`a steel bailer and a.two:'-'stage'submersible pump: Ground water'was'-purged from each monitoring well, il'grqu,n.d ' water was visually sediment free.Approxim' ately'25 gallons of water were removed from each well, Ground water temperature, pH and conductivity were measured at regular intervals during purging.: " using, Oakton water analyzer.Field sheets and data are included in Appendix D.Purged water was; stored on--site in properly labeled, 55-gallon DOT-approved drums. ' On 27 July 2004;a.California state-licensed survey engineer from Baumbach&Piazza,'Inc.surveyed a reference point on the top'of each ground water monitoring well at the site to the nearest 0.01-foot` . relative to the San Joaquin County Bench Mark #Z-39 at 44:076 feet above'inean'sea Ievel''(msl)., The results of the monitoring well survey are contained in Table I.-The surveying report(Baumbach ` & Piazza) is presented in Appendix E. 2.6. WELL MONITORING.AND,PURGING '• On 3.1 March 2004,'monitoring.wells MW 1 through MW 12 and domestic water wells DW5157 and .DW5055 were purged and sampled` A Solinst water level meter was used to�rrieasure the depth,to ground water to the nearest 0.01-foot in the�twelye monitoring wells relative to the tops'ofthe well ' casings. The ground water elevations and gradient were determined from these data,(Table I).' After.recording water level measurements, new disposable plastic'baile'rs were used'to purge each . . monitoring weld of standing-water:'�Between 5:0 and'.7.5 gallons of water. (a minimum of 3 casing-water volumes per well)were removed from each well. Ground water temperature,pH and conductivity were measured'at-regular intervals during purging,using an Oakton water analyzer. To. 1 _ .- ,urg"e DW5157 and.D.W5055 a hose bib was. o eried:on thewater`storage,tank. The pump was - allowed't6,cycle on and-off for,approximately 15 minutes. Field sheets and data are included in ' Appendix F. Purged water was stored on-site in labele,d,,55-gallon DOT-approved.drums. 2.7. - COLLECTION OF'GROUNDWATER-SAMPLES ti Awater'sample was collected from each purged well using'a:new disposable plastic bailer: To sample DW515.7'and DW5055 a hose bib was opened on the water storage tank and samples were' i.. collected from•,,the.tank while the pump'was operating io obtain a fresh water sample. All samples. . were transferred-into.'one 1-liter amber bottle without sample preservative and.into three,40-m1 volatile organic analysis (VOA)' vials containing 0.5 ml 18%0: hydrochloric .acid `asa 'sample ' preservative. ; Advanced GeoEnvironmental,Inc.