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26 September 2003 <br /> • AGE-NC Project No. 98-0500 <br /> ' Page 2 of 5 <br /> 2.2. GROUND WATER SAMPLING <br /> Water samples were collected from each monitoring well using dedicated disposable or dedicated <br /> ' Waterra bailers after allowing the wells to achieve a minimum 80%recovery of the pre-purge water <br /> volume. The samples were transferred into three 40-m1 EPA-approved volatile organic analysis <br /> (VOA) vials containing 0.5 ml 18% hydrochloric acid as a sample preservative, one-liter amber <br /> ' bottles lacking preservative and 500 ml bottles. Care was taken to ensure that visible air bubbles <br /> were not present in the VOA vials after filling and capping. The ground water sample containers <br /> were subsequently labeled with the well designation, date, time, and sampler's initials. <br /> 2.3. LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br /> ' Eachound water le was logged on a chain-of-custody form,placed in a chilled container and <br /> �' sample <br /> shipped to McCampbell Analytical,Inc. (MAI),a California Department of Health Services(DHS)- <br /> certified analytical laboratory. Selected samples were analyzed for: <br /> • Total petroleum hydrocarbons quantified as gasoline and stoddard solvent (TPH-g and <br /> • TPH-ss) in accordance with EPA Method 8015 Modified; <br /> • Volatile organic compounds(VOCs),including benzene,toluene,ethylbenzene and xylenes <br /> (BTE&X) and the fuel additives methanol, ethanol, ethylene dibromide (EDB), 1,2- <br /> dichloroethane(1,2-DCA),tertiarybutanol(TBA),di-isopropyl ether(DIPE),ethyl tertbutyl <br /> ether(ETBE), tert amyl methyl ether(TAME),methyl tertiary-butyl ether(MTBE)by EPA <br /> ' Method 8260B; and <br /> • Total Lead by EPA Method 200. <br /> 3.0. FINDINGS <br /> ' Ground water elevation, flow direction and gradient were determined from field data collected on <br /> 09 July 2003. The contaminant impact to ground water was assessed from the ground water <br /> laboratory data. <br /> 3.1. GROUND WATER ELEVATION AND GRADIENT <br /> In the AGE-prepared Monitoring Well Installation Report, dated 08 October 2002,AGE identified <br /> four informal hydrologic units(HU)on the basis of the physical characteristics of the soil developed <br /> • from analysis of soil samples from well and CPT borings. Shallow-screened (40 to 60 feet below <br /> Advanced GeoEnvironmental,Inc. <br />