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_ o p4g_21 1 APPENIAX A PR6TOCOLS FOR WELL DRILLING,COMPIXTION, DEVELOPMENT,AND SAMPLING A.I DRILLING The boreholes are drilled with a truck-mounted rotary drill using 10-inch outside diameter hollow-stem,continuous-flight augers. The borehole is drilled 10 feet below static water but will not penetrate competent clay layers that may act as effective aquitards. Drilling is terminated after two consecutive sampling intervals intersect comparable, apparently impermeable clays below static water. Casing and sand are installed inside the inner opening as the augers are gradually removed. All augers, sampling rods, samplers, and downhole equipment are steam cleaned before drilling and between each new well. All drill cuttings and fluids from steam cleaning are contained onsite in sealed 55-gallon drums. The drums arc labeled with the borehole number,site descrip- tion (including owner's name),depth interval of soil contents,date,and monitoring equipment readings. The drill cuttings are disposed of at proper facilities on the basis of soil sample analy- sis A log of drilling and the borehole are recorded by an EA geologist overseeing the drilling opera- tions and well installation. The boring logs are signed and dated and contain detailed geologic information,including descriptions of the soils classified according to the Unified Soil Classifi- cation System, blow counts,OVA readings, moisture content of the soils, and initial and static water levels. A.2 SOIL SAMPLING Soil samples are collected at 5-foot intervals and at any substantial changes of soil type, begin- ning at 5 feet below ground surface, with a 2-inch-diameter, 18-inch modified California split- spoon sampler containing three 6-inch brass liners. The sampler and liners are steam cleaned before use in each hole; they are scrubbed in deionized water and Alconox detergent and rinsed with deionized water after use at each sampling interval. Soil samples are collected to a total depth of the borehole unless heaving sand occurs. Every attempt is made to collect a soil sample just above or at the water table. At each sample depth, the drive sampler is driven 18 inches ahead of the drill augers into undis- turbed soil. Typically after the sampler is opened,either the lowemtost or middle sample liner is retrieved,and the ends of the tube covered with aluntinuln foil and sealed with plastic caps. The plastic caps are secured to the liner with tape. The soil-filled liner is labeled with the location, e]GR]7d7.1n.y91h,r A-[