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Logging of Borings <br /> Soil samples are logged using the Unified Soil Classification System. Samples not selected <br /> for chemical analysis and the soil sampler shoe are extruded in the field for examination. <br /> The texture, color, moisture, plasticity, and consistency of soil, the blow counts, and <br /> subjective evidence of hydrocarbons, such as soil staining, obvious product odor, and <br /> photoionization detector (or similar instrument) readings are noted in the field on the logs <br /> of borings. <br /> Sampling of Drill Cuttings <br /> Soil samples are collected from the stockpiled drill cuttings by driving a hand-operated <br /> percussion sampler fitted with a clean brass sleeve into the stockpiled soil. The sleeve is <br /> removed from the sampler and promptly sealed with Teflon tape and plastic caps. The <br /> sample is then labeled and placed in iced storage. Chain-of-custody records are initiated by <br /> the geologist and accompany the samples to the analytical laboratory. Pending the <br /> analytical results of the soil samples, Dillard Trucking of Byron, California, will arrange <br /> for disposal of the drill cuttings at an appropriate disposal facility. <br /> Vapor Extraction Well Construction <br /> Vapor extraction wells will be constructed in the borings with thread jointed, 4-inch-inner- <br /> diameter, Schedule 40 polyvinyl chloride (PVC) casing. No chemical cements, glues, or <br /> solvents are used in well construction. The screened portion of each well consists of <br /> factory-perforated casing with 0.10 inch wide slots. The well will extend approximately <br /> from the total depth of the well to approximately 10 to 30 feet below ground surface. The <br /> annular space in the well is packed with pea gravel compatible with well slot size to <br /> approximately 1 to 2 feet above the slotted interval. A 3-foot-thick bentonite plug is added <br /> above the sand pack to prevent the cement from entering the well pack. The remaining <br /> annulus was backfilled to grade with a bentonite cement slurry. <br /> Wells are protected with a traffic-rated, cast-aluminum utility box equipped with a PVC <br /> skirt. The box has a watertight seal to protect against surface water infiltration and must <br /> be opened with a special wrench. The design of this box discourages vandalism and <br /> reduces the possibility of accidental disturbance of the well. <br /> SACW:\PJO\0805\08051520.3AL-94\ci c:I A-2 Rev.O,6/8/95 <br />