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35 I would agree that the angle of internal friction equals the angle of repose only in the case of a theoretical non-cohesive (granular) soil, such as dry well-sorted silica sand. In the realistic case of cohesive soils, such as the colluviaUresidual clay soils and the anticipated spoil at the Lorencito Canyon Mine, this generalization is inappropriate. In my opinion this assumption should be amended to read; "The angle of repose of cohesive soils is considered an indicator of the maximum possible friction angle of these materials. Razely will the friction angle of these materials approach that theoretical maximum limit." Frankly, I do not believe this potentially flawed statement adds to the presentation and might better be deleted. Design and Coustructiou Recommendations As a result of their pazametric analysis, CTL/I'hompson, Inc. forwards detailed recommendations for use in the eventual design and construction of the Lorencito Canyon Mine spoil fills. I concur with the majority of their recommendations. My following comments address only recommendations with which I disagree or which require more detail. Site Prepazation "If reconnaissance indicates localized unstable areas which could affect stability, the best procedure may be excavation of the unstable mass." Caution should be exercised by the operator in applying this suggestion. Excavation of a failed mass may remove the lateral support for adjacent upslope materials and only exacerbate the instability of the upslope material resulting in a lazger failure. "If a localized steep valley side slope results in classification as a valley fill this could require the lazge drains associated with valley fill regulations. It may be advantageous to cut these slopes to less than 20 degrees." Rule 1.04 (148) states; "'Valley fill' means a fill structure consisting of any material other than coal waste and organic matter that is placed in a valley where side slopes of the existiug valley measured at the steepest point aze greater than 20° or the average slope of the profile of the valley from the toe of the fill to the top of the fill is greater than ]0°." (emphasis added) The word "existing" was used in the regulatory definition to disallow this sort of avoidance. However, the Division would measure the side slope gradient over an appropriate chord length. "Slope" is not a point characteristic. There is no written policy for this determination. It is a judgement made by the reviewing professional. Small steep segments may not be significant in completing the determination of slope gradient. Further, I suspect it would not be practical for the operator to attempt to amend large areas of the slope to avoid classification as a "valley 511". Fill Placement On page ]4 of Exhibit #13, CTL/Thompson, Inc. States; "CDMG regulations require that