Laserfiche WebLink
1.4 METHODS AND PROCEDURES <br /> 1.1 SO Samnlins! and Contamination Reduction <br /> Drilling and soil sampling was performed under the direction of a Delta geologist. The soil borings were <br /> advanced using a truck-mounted hollow-stem auger drill rig. To reduce the chance of cross <br /> contamination between boreholes, all downhole drilling equipment was pressure-washed between each <br />' soil boring. To reduce cross contamination between samples, the split-barrel sampler was washed in a <br /> soap solution and double rinsed between each sampling event. <br /> Soil sampling was conducted in accordance with ASTM 1586-84, utilizing a 2-inch inside-diameter <br />' split-barrel California-type sampler lined with three 6-inch long brass sample tubes. At each selected <br /> sampling depth, the sampler was driven 18 inches into relatively undisturbed soil by a 140-pound weight <br /> falling 30 inches. The number of blows required to drive the sampler each 6 inches was recorded on the <br /> soil boring logs. <br />' <br /> Upon recovery, a portion of the soil sample was placed into a plastic bag and sealed for later screening <br />' with a photoionization detector (PID) as described in Section 1.3. A representative portion of the soil <br /> sample was used for classification and description. The soil sample collected in the leading brass tube <br /> within the California-type sampler was labeled, sealed, and stored on ice for transport to the laboratory. <br />' 1.2 Soil Classification <br /> As the samples were obtained in the field, they were classified in accordance with the Unified Soil <br />' Classification System. Representative portions of the samples were retained for further examination and <br /> for verification of the field classification. Logs of the borings indicating the depth and identification of <br />' the various strata were maintained by the field geologist. <br /> 1.3 Soil-Sample Screening/ Portable Photoionization Detector Method <br />' After the soil samples in the plastic bags warmed to approximate ambient temperature, the headspace <br /> vapors were screened with a portable PID equipped with a 10.2 eV lamp calibrated to benzene. The <br /> sample bag was opened and the detector probe immediately placed within the headspace of the bag. The <br /> highest observed reading was recorded. This number provides a relative comparison of petroleum <br /> hydrocarbon concentrations but is not quantitative. <br /> RPTto3.5]H <br />