Laserfiche WebLink
Dollhopf et al . , (1981) recommends a 600 meter grid (1 hole/90 acres) <br /> for initial characterization followed by additional drilling and <br /> analyses if any parameters of concern are indicated in the initial <br /> drilling. The circular zone of data extrapolation or the effective <br /> drill hole radius should be 750 feet. Lastly, Sutton et al . (1981) <br /> recommends sampling one site to adequately assess overburden variability <br /> on small permit areas of less than 40 acres. <br /> Seven core holes have been sampled over about 185 acres at Nucla Mine <br /> from 1976 through 1980. One of these holes (2C) was located within 300 <br /> feet of Mine Areas 2 and 3. The sampling density of 1 hole/25 acres <br /> meets the hole intensity criteria discussed above to adequately describe <br /> the OIU variability. Drill hole descriptions and textural analysis <br /> (Tables 6-6 and 6-7) indicate that there is little lateral variability <br /> in the local depositional environment. <br /> Based upon the low variability, Peabody drilled and sampled one OIU core <br /> hole in the 105 acre (actual disturbance area is 35 acres) study area <br /> which encompasses Mine Areas 2 and 3. In addition, three OI cutting <br /> holes were drilled and sampled for Mine Areas 2 and 3 to accurately <br /> delineate areas of acidic and/or saline overburden and interburden. <br /> Sample Contamination. Numerous overburden sample contamination problems <br /> have been documented over the last 10 years in the western United <br /> States. Drilling fluids, foam additives and muds can appreciably affect <br /> the soluble constituents (especially EC, SAR and NH4) in the sample. <br /> During rotary drilling for cores or cuttings, it is necessary to use a <br /> drilling medium such as air, water or mud for lifting cuttings from the <br /> borehole. For overburden baseline studies, it is recommended that air <br /> be used whenever possible, water second and mud (or foam) avoided unless <br /> absolutely necessary to overcome circulation problems or to lift <br /> cuttings from deep holes (Barrett et al . , 1980; Power and Sandoval , <br /> 1976; Dollhopf et al . , 1981; and Peabody Coal Company, 1985) . A <br /> chemical analysis should be obtained on the water, foam and/or drilling <br /> mud whenever they are utilized. <br /> 6-20 Revised 3/6/87 <br />