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<br />• of 3:1 (H:V) would be expected to result in favorable stability conditions unless very <br />poor foundation are present or water developed in the fill. This is confirmed by the <br />analysis. Poor foundation conditions could occur in comparatively small, narrow <br />areas in drainageways where remediation by removal will be relatively easy. Ground <br />water conditions will be controlled by drains. Localized unstable areas will need to <br />be addressed on a case by case basis. <br />To summarize, the stability analysis indicates stable fill meeting CDMG <br />requirements should be possible at the locations and configurations planned. Pre- <br />construction site specific investigations should be performed for each disposal area <br />to identify localized hazards (slumps, slides or seeps); and to confirm soillground <br />water conditions, strength properties and topographic conditions. <br />Analysis Sections <br />The sections analyzed are shown on Fig. A-I and were classified into "high" <br />• and "low" analysis sections. We reviewed topographic conditions at all 21 fill <br />locations (Fig. 1) to develop the sections. The sections are perpendicular to the <br />face, parallel to the drainageway, as shown on Fig. 2. With the fill slope determined <br />(3:1, H:V, average), the inclination of the soil/bedrock layers, thickness of the soil <br />layer and height of the fill are the remaining geometric conditions which will affect <br />the stability calculations. <br />Most of the fills (18 of 21) can be represented by the high fill section. The low <br />fill section is appropriate for Fills 15 and 16. Plans show the topography at the base <br />of the 18 high fills typically consisted of a flatter initial section (7% to 12.5%) for the <br />lower 40 to 60 percent of the fill length, with a steeper back portion with an average <br />slope on the order of 25 percent. These proportions were relatively consistent over <br />the various fill heights. For the high fill section, fill heights (toe to crest) range from <br />5o to 250 feet. Soil layer thicknesses are anticipated to be on the order of 5 to 15 <br />feet near the tae, becoming shallower uphill. The high fill analysis section represents <br />• a conservative condition with the steeper 12.5 percent inclination of the base, a fill <br />LORENCITO COAL COMPANY <br />CM 25,251 7 <br />