Laserfiche WebLink
former location of the underground storage tank (UST) . A truck mounted <br /> drilling rig equipped with eight-inch diameter hollow stem augers was <br /> used to drill the boreholes. Samples were obtained using a California <br /> modified split spoon sampler at five foot intervals. Boreholes BH1, <br /> 0 BH3, BH4, and BH5 generally correspond with the locations in the LBME <br /> proposal numbered one, three, four, and five. The locations of the <br /> boreholes are shown in Figure 4-1. During the drilling, an organic <br /> vapor analyzer (OVA) was used to periodically monitor for volatile <br /> organic compounds (VOC) in the drilling area. No VOCs were detected in <br /> the ambient air samples except for low levels in some fresh drill <br /> cuttings at the surface of the borehole. <br /> During the drilling, soil cuttings from the boreholes were <br /> continually monitored for changes in lithology or indications of <br /> contamination. The soil samples were obtained at five feet intervals <br /> and were analyzed using an OVA and headspace analytical procedures. All <br /> soil samples to be analyzed by the laboratory were sealed and preserved <br /> in an ice chest using standard methodology and were transported using <br /> proper chain of custody procedures. Boreholes BH3, BH4, and BH5 were <br /> located on the perimeter of the UST excavation site. In each of those <br /> three boreholes, drill cuttings obtained from the augers above the 15 <br /> foot sampling level had a very faint diesel odor. No odor was <br /> detectable in the samples obtained at the 15 foot level ; however, the <br /> OVA detected 0.0, 11, and 0.3 part per million (ppm) of VOCs in samples <br /> from the 15 foot level in boreholes BH3, BH4, and BH5, respectively. <br /> Soil samples from 15 feet below the surface were selected for analysis <br /> from each of the three boreholes. Each of the three boreholes were <br /> completed to a depth of 31 .5 feet below the surface, which was 15 feet <br /> below the deepest detected contamination. <br /> Borehole BH1 was located over the center of the UST excavation site. <br /> The upper 10 feet of soil at that location was comprised of fill <br /> replaced into the excavation pit. Within the fill , the OVA first <br />