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• 11,February 2003 <br /> AGE-NC Project No. 98-0520 <br /> ' Page 4 of 7 <br /> ' respectively, in the sample from MW-9-20. In addition, MTBE was detected at a <br /> concentration of 0.0075 mg/kg in soil sample MW-9-25. <br /> On 25 February 2002, one additional ground water monitoring well (MW--7) was installed on-site . <br /> t. to a depth of 35 feet bsg. A total of 3 soil samples were submitted for analysis. <br /> No analytes .were detected at or above laboratory reporting limits in the soil samples <br /> ' analyzed. <br /> The vertical extent of impacted soil.and ground water has been defined. The lateral extent has been <br /> ' mostly defined, except towards the north/northwest; however, based on soil analytical results at <br /> MW-3, MW-8 and MW-9 (e.g., apparent deeper contamination at MW-8 versus MW-3 and the <br /> presence of MTBE in MW-9), AGE believes that there may be adjacent sites' providing or <br /> contributing to the contamination detected in northernmost wells MW-8 and MW-9. AGE plotted <br /> maximum TPH-g contamination in soil versus distance fromthe source area UST 1 and UST2;based <br /> on a lateral attenuation model (Figure 3), if most of the TPH-g contamination originated from the <br /> UST I.and UST2 source, the TPH-g concentration in soil should attenuate to a non-detectable level <br /> by approximately 210 feet northwest of the source area. <br /> 3.0. SCOPE OF WORK <br /> AGE proposes to advance two soil borings off-site towards the. northwest; in the down-gradient. <br /> direction, to define the lateral extent.of contamination. The additional site assessment will include <br /> ' the following tasks; <br /> • Permitting and pre-field work activities; <br /> ' • Soil and groundwater sample collection'and analysis; <br /> Report preparation. <br /> The additional site assessment tasks are discussed below. <br /> 3.1. PERMITTING AND PRE-FIELD WORK ACTIVITIES <br /> 1 A site assessment boring permit will be obtained from the EHD for all on-site and off-site boring <br /> locations and encroachment permits will be obtained from the City of Manteca Public Works <br /> ' Department.In addition,a health and safety plan will be prepared in accordance with Occupational <br /> Safety and Health Guidance Manual for Hazardous Waste Site Activities (National Institute for <br /> . Occupational Safety and Healih Administration, U.S. Coast Guard and. U.S. Environmental <br /> Advanced GeoEnviron mental,Inc. <br />