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ATTACHMENT 6 pH lies above the lowest coal seam. However, this layer is adjacent [o a layer (133' - 161') containing a high proportion of sandstone which will improve the poor layer by dilution with mixing. The layer (63' - 109', except for coal) in CR 220 with the most serious problem, if exposed, will likely be covered in the mining operation. In hole CR 222 a layer of overburden (149' - 184') occurs between two coal seams. This Layer has a high pH and a high ESP, but it lies next to a sandstone layer (123' - 144') which will improve its properties by mixing. Thus, the degree of mixing is an important factor in estimating how serious a problem may be found with this layer of the overburden. Overburden layers with above normal pH in hole CR 223 exist between 96' - 145' with three coal seams intermixed. The overburden from 114' - 145' has a pH above normal after weathering. This layer has a high clay content and a high ESP. Plant growth less than 50 percent of normal would be likely on this layer of overburden. 3.22 Soluble salts • In the West Panel soluble salts will not likely cause any probelms in the overburden except possibly at CR 218. This hole shows six layers of coal. . The three deepest layers have an overburden of sandstone plus siltstone imme- diately above the coal. Soluble salts will leach quite freely from this over- burden. However, the overburden beneath two of the coal layers is shale and shale plus siltstone and they contain enough soluble salt to create a moderate problem at least initially if they appear at the surface. The lower of these two layers has a high ESP value. However, the deepest layer (263' - 286') con- tains less salt and a lower ESP, and this layer is not likely to cause problems. In the East Panel soluble salts will not likely cause problems with the overburden in holes CR 219 and 221. Soluble salts in the overburden of some layers in the remaining holes can be expected to cause minor problems in their use if they occur at the surface. These soluble salts are associated with shale (fine texture) and high ESP values. Some leaching of salts from the overburden can be expected before revegetation procedures begin. In hole CR 220 the lowest layer (161' - 172') with moderate salts and a high ESP lies adjacent to a sandier layer (133' - 161') with a lower ESP. Mixing of these two layers is likely and the mixed layer should cause minor prob- lems with soluble salts because leaching will remove them to lower levels. Soluble salts in the overburden (150' - 184') of CR 222, which lies above the lowest coal seam, can be expected to reduce plant growth unless mixing occurs with the layer above (124' - 144'). This mixing would improve water per- meability and increase the leaching of salts. • Soluble salts in the overburden layers of CR 223 from 16' - 145' will likely reduce plan[ growth moderately. Three coal seams appear in this depth interval. A sandstone layer that could improve the leaching of salts lies a[ • a shallower depth of 47' - 80' so the chance for mixing is small. 12