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08 December 1998 <br /> AGE-NC Project No. 95-0109 <br /> Page 2 of 5 <br /> 2.2. COLLECTION OF GROUND WATER SAMPLES <br /> The depth to water in each purged well was remeasured after purging to ensure a minimum of 80 per <br /> cent recharge prior to sampling. Water samples were collected from each purged well using <br /> disposable plastic bailers. Immediately upon retrieval,the samples were transferred into 40-m1 EPA- <br /> approved VOA vials containing 0.5 ml 18%hydrochloric acid as a sample preservative.The samples <br /> were labeled, stored on ice, and transported in a chilled container, under chain-of-custody, to <br /> McCampbell Analytical, Inc. (MAI) in Pacheco, California, a California Department of Health <br /> Services (DHS)-certified laboratory. All samples were analyzed for: <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> Method 5030/8015m; <br /> • Volatile organic compounds (benzene, toluene, ethylbenzene and xylenes; BTEX) with <br /> methyl tertiary-butyl ether(MTBE) in accordance with EPA Method 602; and <br /> • Volatile organic compounds with oxygenated compounds (di-isopropyl ether [DIPS], ethyl <br /> tertiary-butyl ether[ETBE], MTBE,tertiary-amyl methyl ether[TAME] and tertiary-butanol <br /> [TBA]) in accordance with EPA Method 8260/8260m. <br /> • <br /> Samples were also collected from MW-9 and MW-14 and placed in 40-m1 VOA vials with no added <br /> preservative. These two samples were placed in a chilled container and transported under chain-of- <br /> custody to A. Keith Kaufman, M.S., in Culver City, California. These samples were analyzed for <br /> physicochemical properties and microbiological enumeration. <br /> 2.3. ADDITION OF HYDROGEN PEROXIDE <br /> On 15 September 1998,the addition of hydrogen peroxide to wells at the site was performed. A total <br /> of 106 gallons of hydrogen peroxide, diluted to approximately 1 percent, was added to nineteen <br /> monitoring and vapor wells at the site. The hydrogen peroxide was added to increase dissolved <br /> oxygen concentrations in ground water to promote biodegradation of hydrocarbons. The volumes <br /> added to each well are summarized on Table 1. <br /> 2.4. STRAGIGRAPHIC CROSS SECTIONS <br /> Three cross sections were prepared illustrating the shallow subsurface geology based upon the <br /> numerous soil borings advanced between September 1985 and June 1997. Cross sections are <br /> included as Figures 4 to 6. <br /> • <br /> Advanced GeoEnvironmental,Inc. <br />