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3 (see Exhibits 6-3A and 12-1). Conditions were ideal for chip sampling <br /> because the overburden was both dry and shallow (10 to 20 feet thick) . <br /> Chip samples were collected on two foot vertical increments from the <br /> soil surface to the top of coal . Interburden and the weathered upper <br /> Dakota coal seam,, if present, were always sampled separately while five <br /> to six feet of underburden was also sampled at all locations . <br /> The core and chip samples were described in the field by the driller and <br /> subsequently by a soil scientist. Standard geologic description <br /> information such as lithology, color, hardness , grain size, boundary <br /> conditions , wetness , and presence of fractures , pyrites , gypsum and <br /> carbonates were included. The chip samples and cores were packaged in 6 <br /> mil polyethylene by two foot increments and placed in standardized boxes <br /> for shipment to the lab. At the lab (Intermountain Lab, Farmington, New <br /> Mexico) , chip samples and cores were air dried, split or composited <br /> according to lithologic or stratigraphic sequence, crushed to pass a 10 <br /> mesh sieve and bagged. <br /> Parameter Selection. Overburden and interburden information from the <br /> existing Nucla Mine area (Permit C-008-81, Phase 1) was evaluated and <br /> statistically summarized to select and justify the proposed chemical and <br /> physical parameter list for Mine Areas 2 and 3 (Phase II) . Mean <br /> overburden (above upper Dakota coal seam) and interburden (between upper <br /> Dakota and lower Dakota coal seams) data from the seven Phase I drill <br /> holes is summarized in Tables 6-6 and 6-7. The overburden and <br /> interburden suitability information is presented b; hole for each <br /> parameter in Figures 6-3 through 6-9. Suitability criteria were <br /> developed from Barth et al . (1981) , Munshower (1983) and the numerous <br /> literature references included with Table 6-4 in the OIU Suitability - <br /> Phase II section. The Colorado Water quality and Overburden Geochem- <br /> istry guidelines suggest 24 chemical and physical parameters to be <br /> evaluated for "roof" and "floor" overburden. These parameters are <br /> discussed in further detail for the seven Phase I core hole locations at <br /> the Nucla Mine site. <br /> 6-22 Revised 3/6/87 <br />