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APPENDIX A <br /> GENERAL FIELD PROCEDURES <br /> DRILLING AND SOIL SAMPLING <br /> Wells will be drilled using 10-inch-diameter, continuous-flight, hollow-stem augers. To avoid <br /> cross-contamination, the augers will be steam cleaned prior to drilling each boring. <br /> Soil samples will be obtained for soil description, combustible gas detector (CGI) screening, and <br /> laboratory analysis. Samples will be collected continuously in all soil borings. Soil samples are <br /> retrieved ahead of the lead auger using a 5-foot-long continuous core sampler. Within the 5-foot <br /> long sampler, sample tube inserts will be driven into the recovered sample at the interval(s) <br /> selected for analysis. The sampler and sample tubes will be washed with an Alconox solution <br /> and rinsed before each sampling event. <br /> Upon retrieval from the samplers, sample tubes will be securely sealed with Teflon sheeting and <br /> polyurethane caps. Samples will be labeled with sample identification, sample depth, geologist's <br /> initials, and date of collection. Samples will be placed in an iced cooler prior to, and during <br /> transport to a California-certified laboratory for analysis in accordance with proper chain of <br /> custody documentation. <br /> The remaining soil recovered will be described in accordance with the Unified Soil Classification <br /> System. For each soil type, field estimates of density/consistency, moisture, color, and lithology <br /> will be recorded on the boring logs. Field measurements of CGI readings in selected soil <br /> samples will also be recorded and included in the boring logs. <br /> WELL INSTALLATION PROCEDURES, <br /> BORING LOGS, AND WELL CONSTRUCTION DETAILS <br /> Observation wells will be constructed using 4-inch-diameter, flush-threaded, Schedule 40, PVC, <br /> blank and screened (0.010-inch slot size) casing. The annular space surrounding the screened <br /> portion of each well will be backfilled with No. 2116 Monterey sand (filter pack) to <br /> approximately 1 foot above the top of the screened section. A 1-foot-thick, bentonite, annular <br /> seal will be placed above the filter pack and the remaining annulus grouted to the surface with <br /> neat cement. Traffic-worthy well boxes will be installed slightly above grade to minimize <br /> infiltration of surface waters. Locking, water-tight well caps will be installed to ensure the well <br /> integrity. <br /> 5 <br />