ARCHIVED REPORTS XR0011668 - Laserfiche WebLink

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LEEDSNlLL-MEAXENNpPF. iNC, inserted down the center of the hollow-stem augers was used to collect the discrete samples from ten of the eleven borings (all except SBI) . The sampler was a California Modified (2.5- inch inside diameter) split-spoon sampler equipped with 6-inch long clean brass liners. The sampler was driven i8 inches into the undisturbed ground beyond the tip of the auger by a 140-pound hammer having a 30- inch drop. The sampler was then withdrawn from the auger and the liners removed. The other boring (SBI) was drilled with a 5-foot long split core barrel attached to drilling rods inserted down the center of the 6-inch hollow-stem augers and secured to the augers with a locking ring. Although the core barrel is 5 feet long, it was found that drilling 2.5-foot core segments produced the most optimal recovery of soil samples for this site' s conditions. As the augers advanced, a continuous sample filled the core barrel . The core barrel was then withdrawn from the auger and the continuous core sample removed. Discrete grab samples were selected from the continuous core for laboratory analysis by the field geologist. The split-spoon sampler and split core barrel were brushed and washed with a trisodium phosphate (TSP) solution and rinsed in clean water between each sampling interval . All sample liners and drilling equipment were thoroughly cleaned with high pressure, hot water prior to use to prevent potential cross- contamination between borings. The test borings were completely backfilled with a cement-bentonite grout mixture immediately after the samples were obtained. The drill cuttings produced from each of the boreholes were containerized in 55- gallon drums with lids and stored on-site to await disposal based on the results of the analytical testing. Once removed, all samples were capped, sealed, carefully marked, and identified. The samples were then carefully preserved for analysis in accordance with EPA and California Department of Health Services (OOHS) protocol . Before transport to the laboratory, samples were cooled to 4 Celsius at the site and maintained at that temperature until they were received at the laboratory. Prior to transport, the samples were logged onto a chain-of-custody form identifying the project number, sample type, container type, sample identification, type of analysis, sampler and date. The samples were picked up at LH' s office by a Superior Analytical Inc. representative, who signed the chain-of-custody form. All samples were obtained under the supervision of the field geologist. A • detailed boring log was kept at all times noting soil types encountered, using the Unified Soil Classification System (USCS) , and noting moisture conditions, location, and depth for each sample. Copies of the boring logs and the USCS are presented in Appendix B. A photoionization detector (HNU) was used to field monitor volatile organic vapors emitted from each sample and to assist the field engineer in determining whether or not background volatile organic vapors were present at the site. No ambient background volatile organic vapor concentrations were detected. The field-detected photoionization values for each sample are shown on the geologic j logs presented in Appendix B. These field instrumentation readings did not 1 replace the analytical laboratory testing. l 9 i