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• V <br /> 27 May 1992 <br /> (GeoAudit MDC Ukiah-1. 9) <br /> Page 4 of 5 <br /> pg/g and 190 pg/g, respectively. Sample NW-30 was not analyzed <br /> because field screening showed significant amounts of contamination <br /> was still present in this area. TPH as gasoline was not detected in <br /> the remaining samples from this portion of the excavation (NW-40B, <br /> NW-50B, NW-60, NW-70 and WW-1 & WW-2) . BTE&X was detected at trace <br /> levels in sample NW-40B (toluene and xylenes at 0 . 0058 and 0 . 012 <br /> Ag/g, respectively) . <br /> The results of the soil sample analyses are summarized in Table 1. <br /> The laboratory reports and chain of custody forms are attached. <br /> PARTIAL BACKFILL PROCEDURES <br /> Field observations during the first phase of excavation justified <br /> the removal of soils below the water table, increasing the <br /> estimated volume. Due to saturated conditions at 11 feet, the lower <br /> 5 feet was backfilled with 1. 5-inch drain rock and pea gravel. A <br /> layer of geo-fabric was placed over the gravel and soil which did <br />• not indicate the presence organic vapor was subsequently <br /> backfilled. <br /> CONCLUSIONS <br /> In total, approximately 2, 450 cubic yards of contaminated soil were <br /> removed and transported to an on--site treatment area. The water <br /> seepage in the lower portion of the excavation indicated the <br /> presence of ground water at a depth of approximately 10 - 11 feet <br /> below ground surface. <br /> Based upon the non-detection or only trace concentrations of TPH <br /> and BTE&X in the samples obtained along the northwest and southwest <br /> sidewalls, we believe that the majority of the contaminated soil <br /> within the property line was successfully removed. Furthermore, <br /> benzene was detected only in two samples (SW-40 and SW-50) . This <br /> area was excavated further and an additional sample (WW-2) showed <br /> no detectable benzene levels. <br /> Since removal of contaminated soil under the sidewalks along the <br /> State Street (east wall) or Stephenson Street (northwest wall) is <br /> not feasible, the best effort in active mitigation has been <br /> completed. Following site restoration, wells will be reinstalled to <br /> monitor the degradation of the remaining hydrocarbon contamination. <br /> t <br />