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' FIELD PROCEDURES <br /> . FOR <br /> ' DRILLING AND SAMPLING <br /> AND GROUNDWATER MONITORING WELL INSTALLATION <br /> ' Drilling Procedures <br /> The soil borings were drilled using 8-inch-diameter, continuous-flight, hollow-stem augers. <br /> ' To avoid cross-contamination, drilling equipment in contact with potentially-contaminated <br /> material was decontaminated by steam cleaning before and after each use. Decontamination <br /> fluids were placed into Department of Transportation approved drums for disposal. <br /> Soil Saml2ling Procedures <br /> During drilling, samples were collected beginning at 5 feet below grade and terminating at <br /> the total depth of each boring. Before and after each use, the sampler was washed using a <br /> phosphate-free detergent followed by tap water and deionized water rinses. Soil sampling <br /> ' was accomplished using a California-modified split-spoon sampler lined with brass tubes. r <br /> A 140-pound slide hammer falling 30 inches was used to advance the sampler 18 inches <br /> ahead of the hollow-stem augers into undisturbed soil, and blow counts were recorded for <br /> every 6 inches of penetration to evaluate the consistency of the soil. <br /> 1 <br /> After retrieval from the augers, the sampler was split, the sample tubes removed, and a soil <br /> sample was selected for possible chemical analysis. The sample was retained within the I <br /> brass tube, and both ends were immediately covered with Teflon sheeting and polyurethane <br /> caps. The caps were sealed with tape and labeled with the following information: Ahsto <br /> ' Engineering project number, boring number, sample depth interval, sampler's initials, and <br /> date of collection. The soil sample was immediately placed in a waterproof plastic bag and <br /> stored in a cooler containing blue or dry ice. Possession of the soil samples was documented <br /> from the field to a state-certified analytical laboratory by using a chain of custody form. <br /> ' Soil samples and drill cuttings, when appropriate, were described by Alisto Engineering <br /> g <br /> personnel using the Unified Soils Classification System, and field estimates of soil type, color, <br /> ' moisture, density, and consistency were noted on the boring logs. The logs were reviewed <br /> by a civil engineer registered in the State of California. <br /> ' Groundwater Monitoring Well Installation <br /> Construction of the groundwater monitoring wells was based on the stratigraphy in the soil <br /> ' borings. The well construction materials were introduced into the boring through the <br /> hollow-stem augers to centralize the well casing and minimize the possibility of native <br /> material entering the annular space of the well. <br /> 1 The 2-inch-diameter polyvinyl chloride well casing consisted of 0.010-inch slotted casing from <br /> the bottom of the boring to a depth interval above the highest anticipated water level, and <br /> t solid casing was installed from the top of the slotted casing to approximately 0.5 foot below <br /> grade to accommodate the utility box. The casings, fittings, screens, and other well <br /> construction components were steam cleaned before installation. <br /> 'r <br />