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WGirlk <br /> Southwest, Inc. <br /> Data from nearby studies indicate that the current depth to groundwater in the vicinity ranges <br /> from about 5 to 10 feet bgs (SPGC, 1998, and EMCON, 1998). Seasonal fluctuations in the <br /> water table appear to range from about 3 to 5 feet, with some as much as 6 to 9 feet. Based on <br /> nearby studies (SPGC, 1998 & EMCON, 1998) groundwater flow directions in the vicinity <br /> appear to be variable, ranging from west northwest to east southeast. Flow direction changes <br /> may be due to tidal influences produced by the deep water channel to the north and the San <br /> Joaquin River to the west and southwest of the Port of Stockton complex.I <br /> According to Port of Stockton monitoring records, the groundwater pH ranges from 7.1 to 7.4. <br /> During the course of this investigation, soils encountered beneath the site consisted of fine-grained <br /> sediments in the upper ten feet. These sediments ranged from silty, sandy clay to silty very fine <br /> sand in the upper portion of the interval, grading to clay in the lower portion. The ten to fifteen foot <br /> interval was a mixture of fine and coarse-grained sediments ranging from clayey, sandy silt to silty <br /> fine sand. The fifteen to twenty-five foot interval consisted mainly of coarse-grained sediments <br /> ranging from fine to coarse sand with some gravel present. <br /> 5.0 PURPOSE AND SCOPE OF WORK <br /> The investigative work described within this report was conducted in response to an agency <br /> request for the collection of groundwater samples (Notice of Violation dated July 16, 2003). The <br /> purpose of the required assessment work has been to evaluate the impact to local groundwater <br /> from the April 18, 2003 accidental spill of approximately 5,500 gallons of ammonia hydroxide. <br /> Three groundwater wells were installed, as indicated on Figure 3, in order to investigate impact to <br /> groundwater from the spill. <br /> 1 Port of Stockton, UST Site No. 3, Project Status Report of Groundwater Monitoring and <br /> Sampling, 4th Quarter 2002, pages 1 —2. <br /> 725.PRI.00 Page 3 December 4,2003 <br />