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of geologic and geochemical conditions (i.e., lateral variability of strata) existing at <br />each mine site. <br />Recommended drilling intensities range from one hole per 40 acres to one hole per 640 <br />acres. CMLRD (1982) suggests sampling 1 drill hole/640 acres with a minimum of 3 <br />holes/site. USDI-OSMRE (1985a) recortonends drilling 1 hole/160 acres with a minimum of 3 <br />holes/site. WDEO (1985) stipulates sampling 2 core holes and 6 cutting holes per 640 <br />acres during Phase I drilling. Phase II sampling is reserved for special handling <br />situations, and a density of 1 hole/40 acres is recommended. Dollho pf et al. (1981) <br />recommends a 600 meter grid (1 hole/90 acres) for initial characterization followed by <br />additional drilling and analyses if any parameters of concern are indicated in the initial <br />drilling. The circular zone of data extrapolation or the effective drill hole radius <br />should be 750 feet. Lastly, Sutton et al. (1981) recommends sampling one site to <br />adequately assess overburden variability on small permit areas of less than 40 acres. <br />A Phase I drilling program was implemented at Yoast in 1980 in conjunction with a USCS <br />ground water study to describe overburden characteristics over the study area, to obtain <br />representative core hole locations from which cross sections could be developed, and to <br />define the extent of suitable, marginally suitable, and unsuitable material. Six drilling <br />locations were selected after evaluating the geologic cross section requirements and <br />existing coal cropline/recovery information. Overburden (defined as all st ratigraphy <br />above the Wadge coal seam) thickness at Sites 2314E, 2318E, 2309E, 2316E, 2315E, and 2317E <br />was approximately 33, 33, 70, 92, 95, and 104 feet, respectively. The locations of these <br />holes are shorvn on the enclosed map. The Phase I sampling density of 1 hole/65 acres <br />meets the hole intensity criteria discussed above to adequately describe the overburden <br />variability. Drill hole descriptions and chemical/physical analysis indicate that there <br />is little lateral variability in the local depositional environment. <br />Overburden lithology within the Yoast study area is very similar to the Wadge mining area <br />at Seneca II and II-W. Fine sandstone and si ltstone are dominant in the 50- to 60-foot <br />thick overburden section between the Lennox and Wadge coal seams. A thin 1.5-foot thick <br />shale zone occurs directly above the Wadge coal seam. The five- to six-foot thick Lennox <br />coal seam is capped by a five-foot thick hard sandstone strata. More than 75 feet of <br />shale and clay overlie this sandstone strata. <br />Based upon the low variability, Peabody recommends drilling and sampling four Phase <br />2 <br />3 <br />