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Coal Quality Data Review for Colowyo Coal Company <br />• <br />reviewed the drill hole files and updated the database. When creating the <br />cross - plots, HGC excluded roof and floor samples. <br />HGC then created detailed cross -plots with the data subdivided by company <br />for dry basis and as- received basis moistures, see Figure 1 and Figure 2, <br />respectively. Within the Collom Area the data comes from three sources: <br />KEC, Utah International (Utah) and W.R. Grace (Grace). HGC also added <br />information from the Mine Area production data and the Mine Area drill hole <br />data to the detailed cross plots. <br />HGC used the detailed cross -plots to derive a set of regression curves and R <br />values for each data set. The regression curves allowed HGC to compare <br />Btu /lb values for a given ash value. Table 1 contains the regression equation <br />for each data set. Table 1 also lists the Btu /lb differences between each data <br />for an average Dry Ash value of 5.4 %. (The 5.4% dry ash value equates to <br />• an average 4.5% as- received ash values at 16.5% moisture. The 4.5% <br />average ash value was determined from the Mine Area "Last Pass" quality <br />data.) <br />Figure 3 and Figure 4 illustrate the relationships between the data sets <br />without the data points. Table 1 and Figure 3 illustrate that KEC Collom coal <br />quality data is very similar to the KEC Mine Area coal quality data. In HGC's <br />opinion, this provides some solid evidence that the ash and Btu /lb in the <br />Collom area will be similar to the Mine Area data. <br />Table 2 and Figure 4 illustrate how moisture affects relationships between <br />data a sets. However, these charts still illustrate that the KEC Collom Drill <br />Hole Data behave very similar to the Mine Area drill hole data. <br />• <br />July 2004 Page 8 of 16 <br />