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3.1.2 Drilling,Soil Sampling,and Logging Methods- Prior to beginning drilling <br /> operations and between each location, all drill rig and sampling equipment was <br /> decontaminated using high-pressure wash and steam-cleaning equipment. Monitoring <br /> well boreholes were drilled using a 8-inch diameter hollow stem auger. In the <br /> unsaturated zone,samples were collected at five-foot intervals using a California- <br /> modified split-spoon sampler. Geologic logging of boreholes addressed the following <br /> elements: <br /> ■ Borehole designation and location. <br /> ■ Times and dates that drilling/excavation began and ended. <br /> ■ Type of exploratory equipment being utilized, including manufacturer, make, and <br /> model for special modifications. <br /> ■ Name of geologist responsible for log description. <br /> ■ Description of soils according to the Unified Soil Classification System and <br /> description of bedrock materials according to accepted geologic nomenclature. <br /> ■ Systematic descriptions of lithologic and micro-structural changes in strata or soil <br /> horizons, including thickness of units as well as the depth and elevation of <br /> lithologic changes. <br /> ■ Presence of and depth to groundwater. <br /> ■ Sampling interval(s). <br /> ■ Drilling advancement in feet-per-hour(average) and/or feet-per-minute, noting <br /> periods of difficult or very easy drilling. <br /> ■ Any subsurface structures or unusual features encountered. <br /> ■ Descriptions of mineral seams and fracture fillings. <br /> ■ Depth and thickness of weathering. <br /> Copies of the boring logs are included in Attachment 1. <br /> Drill cuttings were piled on the round near each drilling site as allowed in the EMP <br /> g p g <br /> Workplan. <br /> Because the subsurface materials were too dense to permit groundwater sampling using <br /> HydropunchT"" methods,temporary wells were constructed within each borehole.The <br /> temporary well was constructed using one-inch diameter,Schedule 40 PVC casing and <br /> screen with flush-threaded joints to permit hand assembly. The temporary screen <br /> extended 10 to 20 feet upward from the bottom of each borehole,and the screen zone <br /> was backfilled with #2/12 sand. The filter pack sand extended at least one foot above <br /> the top of the screen, and a two-to three-foot thick medium chip bentonite seal was <br /> constructed above the filter pack. The temporary wells permitted collection of <br /> groundwater samples to determine the adequacy of the locations for construction of <br /> permanent monitoring wells. <br /> Well Completion Report ® Page 3 <br /> Corral Hollow Sanitary Landfill ASSOCIATES <br /> May 3,2012 <br />