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' 16 June 2004 <br /> • AGE-NC Project No. 98-0497 <br /> Page 2 of 4 <br />' 2.2. GROUND WATER SAMPLE COLLECTION <br /> Prior to the collection of ground water samples, the depth to ground water was re-measured in each <br />' well to ensure that a minimum of 80% of the initial water volume had recharged. Water samples <br /> were then collected from each well using a clean,disposable plastic bailer.The water was transferred <br /> into one 1-liter amberbottle and three chilled 40-m1 volatile organic analysis(VOA)vials containing <br />' 0.5 ml hydrochloric acid(18%)as a sample preservative. After collection,the samples were labeled <br /> and placed in a chilled container for transportation under chain-of-custody to Cal Tech <br /> Environmental Laboratories(CTEL),a Department ofHealth Services-certified analytical Iaboratory. <br />' Each sample was analyzed for: <br /> • Total petroleum hydrocarbons as gasoline and diesel(TPH-g and TPH-d)in accordance with <br />' EPA Method 8015 Modified; <br /> • Benzene,toluene,ethylbenzene and xylenes(BTEX)and methyl tertiary-butyl ether (MTBE) <br /> in accordance with EPA Method 8021B. <br />' • 3.0. FINDINGS <br /> Ground water elevation and flow direction were inferred from field data. Hydrocarbon-impact to <br />' ground water was assessed by laboratory analysis of the ground water samples. <br />' 3.1. GROUND WATER ELEVATION AND GRADIENT <br /> Ground water elevations were determined by subtracting the measured depths-to-water from the <br />' surveyed casing elevations. The average ground water elevation on 12 March 2004 was 39.8 feet <br /> below mean sea level (MSL) and the average.depth to water was 64.7 feet below casing tops. The <br /> average ground water elevation in the wells increased by approximately 2.4 feet between the <br /> ' December 2003 and March 2004 monitoring events. Ground water was within the screened interval <br /> of each monitoring well. <br /> ' The water table flow direction at the former UST location was determined to be southeast under an <br /> average gradient of 0.002 ft/ft. Figure 3 illustrates the contoured ground water elevations as <br /> measured on 12 March 2004. <br /> 1 <br />' Advanced GeoEnviro n mental <br /> 1 <br />