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10 August 2006 i AGE-NC Project No 98-0497 Page 2 of 4 After water levels were measured, 6 5 to 8 gallons of water (a minimum of three casing water volumes per well) were purged from the wells using a Waterra Hydro-Lift II pump equipped with a mechanical arrn utilized to surge each well with dedicated tubing Ground water temperature,pH, and conductivity were measured at regular intervals during purging using an Oakton water analyzer Field sheets and data are included In Appendix B Purged water was stored on-site in properly labeled,Department of Transportation(DOT)-approved 55-gallon drums pending proper disposal 23 GROUND WATER SAMPLE COLLECTION Prior to the collection of ground water samples,the depth to ground water was re-measured in each monitoring well to ensure that a minimum 80% of the initial water volume had recharged Water ' samples were collected from each well using the inertia pump and dedicated tubing The water was transferred into one 1-liter amber bottle and three 40-milliliter(ml)volatile organic analysis(VOA) without sample preservative After collection, the samples were labeled and placed in a chilled container for transport under chain of custody to Cal Tech Environmental Laboratories (CTEL), a California Department of Health Services (DHS)-certified analytical laboratory in Paramount, California The samples were analyzed for • ' Total petroleum hydrocarbons quantified as gasoline {TPH-g} and diesel (TPH-d) In ' accordance with EPA Method 8015M, and • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and the fuel additive methyl tertiary-butyl ether(MTBE) by EPA Method 8260B ' 2 4 WELL HEAD SURVEY On 05 June 2006, a California state-licensed survey engineer from Baumbach & Piazza, Inc re- surveyed the elevation at the top of the well casing (towc) and the locations for monitoring wells MW-1 through MW-5 Elevations were surveyed to the nearest 0 01-foot relative to City of Stockton Bench Mark 4 179, surveyed at 25 86 feet above mean sea level(MSL) Coordinate locations(x and ' y) of well locations were calculated to the nearest 0 1-foot using coordinate datum NAD 83 from global positioning satellite(GPS)observations The results of the well survey are reported In Table 1, the measured elevations did not vary from the previous casing elevations listed in Table 1 The survey report_(Baumbach & Piazza, Inc ) is presented in Appendix C GeoTracker confirmation _ pages of the uploaded survey information is included in Appendix D 1 • Advanced GeoEnrhronmental,Inc