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the Seneca 11-4 permit area. The proposed Wedge end Wolf Creek coal recovery areas, <br />including the cropLine end recovery line, are delineated on Exhibit b-4. <br />A two-phase overburden sampling program was used within the Yoast permit area to prepare <br />the overburden assessment. Similar phased sampling techniques have been described by USDA <br />(1979), Barrett et el. (1980), Dollhopf et el. (1981), Berth et al. (1981), Dollhapf <br />(1983), MDSL (1983), end WDEO ()985), and ua ed effectively by Peabody Coal Company (1987 <br />and 1988). Phased drilling programs can decrease overburden characterization costs <br />substantially without jeopardizing the quality of date obtained. <br />The following tasks were accomplished during the two phases of overburden analysis: <br />Phase I: The first phase drilling was implemented in 7980 to determine overburden <br />characteristics over the entire study eree end to obtain representative core <br />hole locations from which cross sections could be developed. Following the <br />initial date analysis and interpretation, potential chemical and physical <br />problems were identified, end general areas/strata end percentages of suitable <br />and unsuitable materiel outlined. The site-specif ie horizontal and vertical <br />• variability end discontinuities of strata were evaluated. <br />Phase I1: Four additional sampling locations were approved for the Yoast study eree during <br />June 1990 by CMLRD. Phesa II drilling provided more detailed data to accurately <br />characterize the extent of suitable end unsuitable material. Constituents which <br />approached or exceeded guideline levels during the Phase I sampling were <br />included on the Phase II analyses list. Modifying the second phase parameter <br />list was desirable to reduce unwarrantable analyses costs and to focus on local <br />site-speci tic tontliiions. <br />Semolina Nethodoloav - Phase I. <br />Intensity. Most overburden sampling end analysis studies indicate drilling designs should <br />be governed by geological factors, such as the lithologic variabi Lity and the depositional <br />environment of the overburden strata (Barth et el., 1987). Barrett et el. (1980) states <br />drilling designs end hole spacings must be determined on the basis of the unique set of <br />geologic end geochemicel conditions (i.e., lateral variability of strata) existing et each <br />mine site. <br />• <br /> Recommended drilling intensities range from 1 hole per 40 acres fo 1 hole per 640 acres. <br /> CMLRD (7982) suggests sampling 1 drill hole/640 acres with a minimum of 3 holes/site. <br />11 <br />