ARCHIVED REPORTS XR0010981 - Laserfiche WebLink

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------------- As stated earlier, the excavation was taken to top of ground water. The native soil to that depth (14 feet below the surface) is of a fine sandy, clayey silt. There were no visible preferential pathways observed in the excavations or samples obtained while boring the monitor wells. 3. Figure 2 U.S-G-S topographic map (Tracy, Calif. NW/4 150 Quadrangle, 1954) shows no surface waterbodies near the site. Figure 3A shows the routes of subsurface utility conduits in the vicinity of the site. SAMPLING AND ANALYSIS 1. Were additional samples (other than the minimum required) taken where obviously contaminated soil was present? Yes. All excavated soil was field screened visually and with a photoionizing detector (PID) that was calibrated with a 50 parts per million gasoline vapor standard. No obvious petroleum staining was evident but odor and PID readings were evident from the excavated tank field backfill material and from the ground water discovered at the base of the tank excavation. Samples of the ground water found in the tank excavation and sidewall samples i :j of the tank excavation were obtained. rr.. Initial sampling of the waste nil excavation indicated soil contaminated with motor oil range hydrocarbons. This area was overexcavated and samples were obtained from each sidewall and the base of the overexcavation; all samples were below detection limits. 2. Did sampling and analytical protocols conform to standards described in LUFT and the T-RBSRFPE&IQUTS, 10 August 1990? YES. 3. Were the appropriate laboratory analyses used? YES. 4. Were the laboratory analysis and QA/QC results submitted? YES. 5. In cases of high water table, a) were samples taken from the sidewalls and b) was water present in the excavation pit? pagr 3