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23 April 2001 AGE-NC Project No 96-0229 Page 4 of 7 lying 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 Based on the General Soil Map from the San Joaquin County Soil Survey, published by the United States Department of Agriculture Soil Conservation Service in 1992, the site area is within the Jackson-Hallenbeck-Stockton (JHS) association The JHS soils are located within basins, and generally consist of moderate to poorly drained fine textured soils The soils are generally derived from both marine and non-manne sediment, and are generally formed in alluvium derived from mixed rock sources 2 4 GROUND WATER DEPTH AND GRADIENT . The estimated depth to ground water at the site is approximately 30 feet below surface grade (bsg) based on information from Lanes of Equal Depth of Water Wells Fall 1998, published by the San Joaquin County Flood Control District and Water Conservation District(SJCFCD) Based on review of a regional ground water elevation map published by the SJCFCD, the prevailing ground water flow direction in central Stockton is generally toward the northeast, although flow directions may be both locally and seasonably variable Based on ground water monitoring data collected at the site on 27 March 2001, depth to ground water at the site was recorded at approximately 27 feet bsg and ground water flow direction was inferred to be flowing towards the northeast at a gradient of 0 003 ft/ft i 3.0. SCOPE OF WORK The results of the previous investigations and UST removal activities show that ground water at the site has been impacted The lateral and vertical extent of impacted ground water must be determined prior to the initiation of remediation The assessment activities will consist of the following tasks • Permitting and pre-field work activities, • CPT soil boring advancement, • Grab ground water sample collection and analysis, i • Report preparation Advanced GcoEnvironmental,Inc