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6 July 1999 <br /> AGE-NC Project No. 99-0604 <br /> Page 2 of 5 <br /> 2.2. REGIONAL GEOLOGIC SETTING <br /> The site area is within the Great Valley Geomorphic Province (GVGP) of California, a large, <br /> r elongate, northwest trending structural trough. The GVGP is subdivided into two major divisions <br /> designated the Sacramento and San Joaquin Valleys,which have been filled to the present elevation <br /> with thick sequences of sediment ranging in age from Jurassic to present day, creating a nearly flat <br /> lying alluvial plain extending from the Tehachapi Mountains in the south to the Klamath Mountains <br /> in the north. The western and eastern boundaries of this province are comprised of the California <br /> Coast Range and the Sierra Nevada Mountains, respectively. <br /> `y Based on a General Soil Map from the San Joaquin County Soil Survey, published by the United <br /> States Department of Agriculture Soil Conservation Service in 1992,the soil on the site is described <br /> as belonging to the Jacktone-Hallenbeck-Stockton(JHS) association. JHS soils are located within <br /> basins, and generally consist of moderate to poorly drained fine-textured soils. JHS soils generally <br /> formed from mixed rock sources. <br /> ' 2.3. GROUND WATER DEPTH AND GRADIENT <br /> Based upon the San Joaquin County Flood Control Map Lines of Equal Depth in Water Wells - <br /> 1996,ground water depth in the area of the site is approximately 40 to 50 feet below surface grade. <br /> w Regional ground water flow direction is east-northeast; however, flow direction can vary seasonally <br /> throughout San Joaquin County. <br /> w _ <br /> 3.0. PROCEDURES <br /> The investigation was performed in accordance with the guidelines of both the San Joaquin County <br /> Public Health Services - Environmental Health Division (PHS-EHD) and the Central Valley <br /> Regional Water Quality Control Board for underground storage tank(UST)sites. Moreover,this site <br /> assessment was performed in accordance with AGE's work plan,Preliminary Site Assessment Work <br /> r Plan, dated 20 May 1999 as approved by the PHS-EHD. <br /> w <br /> 3.1. SCOPE OF WORK <br /> w , <br /> The scope of work included the advancement of two soil probe borings to 30 feet below surface <br /> grade (bsg) and to collect soil samples for analysis to determine if petroleum hydrocarbons have <br /> impacted the subsurface of the site at the location of the USTs. <br /> Advanced GeoEnvironmental, Inc. <br /> s <br />