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� r 15 June 1999 AGE-NC Project No. 98-0534 Page 4 of 13 2.4. GROUND WATER DEPTH AND FLOW DIRECTION Based on the San Joaquin County Flood Control District and Water Conservation District Lines of Equal Depth of Water Wells Fall 1996 map, the estimated depth to ground water in the vicinity of the site is 10 and 20 feet below surface grade (bsg). However, significant ground water elevation increases have occurred during 1994 through 1998 and ground water depth at the site may be more shallow than estimated in 1996. Based upon information obtained from the UST removal, ground water is currently at a depth of approximately 15 feet bsg. Based upon data obtained from nearby sites, the prevailing ground water flow direction in the vicinity of the site is estimated to be north. However, flow direction may be both locally and seasonably variable. The Stockton Deep Water Channel is the nearest surface water feature to the property, located approximately 1,750 feet north of the site. Water from the channel drains into the San Joaquin River and is primarily used for commercial and recreational boating, with agricultural as a secondary use. The channel contains water continually and has a potential tidal effect upon ground water depth or flow direction in the area. 3.0. SCOPE OF WORK Based on analytical data from the UST system removal from the site, the PHS-EHD has requested that a soil and ground water investigation to define the Iateral and vertical extent of the petroleum hydrocarbon contamination at the site be prepared. A significant hydrocarbon-impact to soil and ground water has been encountered in the north end of the UST excavation. The proposed scope of work will include the following tasks: • Permitting and pre-field work activities; • Soil sample collection and analysis; • Ground water sample collection and analysis; • Monitoring well installation and sampling; and • Report preparation. Each of these tasks is described in greater detail below. Adronced GeoEnvironmensal,Inc.