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. ADDENDUM TO 4 SITE ASSESSMENT REPORT 21157 N TRETHEWAY ROAD, ACAMPO, CA SITE CODE 4359 RE-EXCAVATION AND RE-SAMPLING 1012011991 PREVIOUS WORK AND REPORTS Two previous reports have been prepared and presented to the San Joaquin County Department of Health Services , Environmental Health Division (EHD) by W J Hunter & Assocs (WJH) They are . (1 ) SITE ASSESSMENT REPORT, dated September 1991 , and (2) WORKPLAN FOR RE-EXCAVATION AND RE-- SAMPLE, dated October 18 , 1991 . These reports are attached. The re-excavation workplan proposed to enlarge the excava- tion at the north end and on the south end and southeast corner These were the areas where the highest contamina- tion had been found This addendum relates the activity at the site subsequent to and as a result of Report # 2 See Figure 1 for site location FIELD WORK PERFORMED 10/20/1991 Activity commenced at about 1 00 PM On site were W J Hunter, Consultant, M Infurna, EHD and R. Thorpe, Contractor About 4 feet laterally was excavated across the south side of the excavation to a maximum depth of 18 feet See Figures 2 and 3 . The soils wore approximately as described in previous reports That is, tan, silty, loamy soil to about 10 feet bgl and harder clayey, silty sand below that point The layer below 14 feet bgl was much harder than that above with one streak of hard, dark grey to brown siltstone with iron staining and root impressions Some fragments of decayed, organic material were found along with thin lenses of gray sand Either varnish-like or degraded gasoline odors were noted to about 13 feet bgl on the south wall Four soil samples were taken from the backhoe bucket at depths suggested by M Infurna, three across the south wall at depths of 13 , 16, 18 feet bgl , and one from the pit bottom at the edge of the newly excavated soil (See Figure 2) . The north wall was undercut and not fully