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• 2.7.2 Overburden Characteristics <br />In 1972, Utah International Inc. recognized the need for a program to analyze the nature of overburden <br />material and its relationship to the revegetation of mine spoils. At that time i[ was thought that all areas <br />might not be retopsoiled. As a resuR, a drilling program was initiated to obtain core samples of <br />representative strata in the proposed mine plan area. This section is a summary of this study. A com- <br />plete study report was compiled by the Ernironmental Sciences Division of Stearns-Roger Inc. and is <br />presented in Append'a 1. Also included in Appendix I are the lithobgic drill hole data from the drill holes. <br />Trapper conduced its overburden drill hole program from 1983-1987. The drill hole data for 1983-1986 <br />is also presented in Append'a I. <br />For evaluation purposes, an assumption is made that normal dragline operations will remove the over- <br />burden above various coal seams and deposit the materials in esserrtially the reverse order of their origi- <br />nal sequence. Grading and transfer of the spoil material will subsequentty result in a considerable <br />degree of muting. Generally, the overburden up to 50 feet above the coal seam will be moved and <br />exposed on the surtace after regrading. <br />Composite samples of each major strata from 12 drill holes, located on approximately 5,000 foot centers <br />across the proposed permit area (Map M36) were sampled and analyzed for the parameters repre- <br />sented in Table 2.7-2 (Stearns-Roger, Inc. 1974). Map M36 also shows overburden core hole locations <br />• that were drilled by Trapper Mining Inc. from 1983-1986 (10 holes). <br />Stearns-Roger's sampling indicated that in some areas of the cemral and eastern portion of the pro- <br />posed permit area, fairly high levels of sodium occur in association with fine textured strata that may be <br />left near the surtace following mining. <br />In addition to overburden analysis conducted by Stearns-Roger, Inc., Trapper has sampled overburden <br />in proposed mining areas in the central and eastern portion of the permit area. Overburden cores were <br />sampled and analyzed in 1983-1986 in various locations minewide with emphasis in the, proposed <br />Ashmore Pit advance. <br />2~s7 .! j REVISION APPROVED <br />` ~ DAT[ ~~/q~`i3 <br />