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, 28 August 2000 AGE-NC Project No. 98-0481 Page 4 of 8 ' 23 feet of piping from rupture to dispenser(up-gradient) x 0.1.6* gal/ft = 3.68 gallons • 40 feet of total piping from UST to dispenser(including the length of piping down-gradient of the rupture) x 0.16* gal/ft= 6.88 gallons • Maximum total = 3.68 gallons+ 6.88 gallons = 10.56 gallons *-Volume of 2-inch diameter pipe==0.16 gal/ft On 01 February 1999, during the repair of the product line, AGE collected two soil samples from beneath the area of the product line rupture. The soil samples were collected from soil boring HA-1 utilizing a hand-auger and a slide-hammer soil sampler fitted with brass sampling sleeves. Soil samples were collected from boring HA-1 at depths of 6 feet bsg and 7.5 feet bsg. As shown on ITable 2, BTEX, TPH-g, and MTBE were detected in soil samples HA-1-6' and HA-1-7.5'. 2.4. REGIONAL GEOLOGIC SETTING The property is situated within the Great Valley Geomorphic Province of California, a large, elongate, northwest trending, asymmetric structural trough. The Great Valley Province has been filled with thick sequences of sediment ranging in age from Jurassic to Recent, creating a nearly flat- Iying alluvial plain, extending from the Tehachapi Mountains in the south to the Klamath Mountains in the north. The western and eastern boundaries of this province are comprised of the California Coast Range and the Sierra Nevada, respectively. Rocks composing the basement complex of the province have not been completely defined but are believed to be metamorphic and igneous in origin. The northern and southern portions of the Great Valley Province have been designated the Sacramento and San Joaquin Valleys, respectively. The Modesto, Riverbank, Turlock Lake Formations and overlying recent alluvium are the principal source of domestic ground water in the 13,500 square-mile San Joaquin Valley Ground Water Basin I (Basin 5-22). This basin is drained primarily by the San Joaquin River. I2.5. GROUND WATER DEPTH AND GRADIENT I Based on the information obtained from assessment activities, depth to ground water in the vicinity of the site is approximately 60 feet bsg. Regional ground water flow direction is generally northwest to north-northeast. However, both ground water depth and flow direction can vary locally and Iseasonally. IAdvanced GeoEnvironmenW,Inc.