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• testing of the Sage Creek coal were available, and no data for this seam were present in the database. Generalized lithology log holes 3319C and 3320C are shown in Figures 22 and 23. As part of the inspection and sample selection process, Rock Quality Designations (RQD's) were calculated. RQD was determined on a 4-inch convention; RQD values aze given on Figures 22 and 23 preceding the unit names. The primary rock type represented in the tested boreholes consists of a brown-to- gray shale (69%). In the core, the shale is relatively intact, with an average RQD of 49. The next most common rock type in the core is sandstone (27%), with an average-RQD of 55. The balance of the column from the tested holes consisted of coal, claystone, and limestone. RQD's of the coal were quite low, averaging 17. This may be due to the fact the core was not fresh and had lost some of its inherent moisture. This probably also explains the low coal compressive strengths from this core compared with coal tests from the Peabody database. During the course of NSA's site visit, general observations of highwall and pit floor conditions were made. At the time, mining had not extended to the Sage Creek or Wolf Creek in the active pits, and only the Wadge Seam was accessible. . The Seneca IIW highwall is generally stable (Figures 24 and 25), with little or no groundwater encountered. The shale, sandstone, and overlying coal seams that make up the highwall appeaz to be very competent, with any small instabilities related to structure rather than rock weakness. The Yoas[ highwall consists of similarly competent material (Figure 26). An old exposure of the highwall (Figure 27) shows more cleazly the structure in the Yoast azea, ~ and suggests that structure dominates here more than in Seneca 11W. ` 2.3 Physical Property Test Results After inspection of the core provided, NSA recommended a suite of uniaxial compressive strength tests to characterize the roof, floor, and seam strata. This was done to provide data for analytical, empirical, and numerical modeling analyses, and to provide a basis of comparison between samples from the study azeas and those from the Peabody database. For selected uniaxial tests, axial strain was also measured so that Young's modulus could be determined. Slake durability tests were also performed to assess the trafficability of the floor materials. In total, 10 uniaxial compressive strength tests with Young's modulus, 11 uniaxial compressive strength tests, and 3 slake durability tests were performed by Advanced Terra Testing (ATT) of Lakewood, CO. ATT's report has been forwarded to Seneca separately. Table 2 summarizes the physical property database used for the analyses described in this report. The abbreviations and strata location classifications given are defined as follows: Seneca Coal Company 4 NSA Engineering, Inc. Highwall Mine Design Report lone 2003