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State Reg. <br />Conclusions <br />Overburden characteristics at the Seneca Mine reflect the <br />depositional environment of coal-bearing strata in this section <br />of the Williams Fork Formation. Significant chemical <br />differences were noted between Wadge and Wolf Creek overburden <br />and between the overburden and underburden sections. The <br />differences were most notable among the parameters pH and <br />sodium. The mean pH level of the Wadge overburden (7.9) was <br />significantly higher than that for the Wolf Creek overburden <br />(6.5). The SAR of the underburden (6.8) was significantly <br />higher than the overburden (1.4). <br />In most instances, normal overburden mixing will effectively <br />dilute and mitigate potentially inimical zones as documented in <br />Table 6-6. However, in the Wolf Creek mining area, selective <br />dragline handling techniques (mixing, segregating/burying acid <br />• strata, and/or segregating/topdressing with suitable material) <br />may be required to eliminate unsuitable pH and ABP levels at <br />the regraded spoil surface. Regraded spoil will require a <br />selectively handled suitable spoil topdressing or lime <br />application if surface pH levels are continuously below 5 and <br />ABP values are more negative than -5. <br />The resultant loamy textured spoil will possess suitable <br />physical qualities which are conducive to productive plant <br />growth. The available water holding capacity would be moderate <br />(approximately 0.07 to 0.16 inches of water per inch of soil), <br />permeability moderate (about 0.6 to 2.0 inches per hour), and <br />cation exchange capacity low to moderate (8 to 15 <br />milli-equivalents per 100 grams). Since the spoil contains a <br />high percentage of rock fragments, it does not possess <br />desirable seedbed and tillage characteristics. <br />• The chemical properties of the spoil are also quite favorable. <br />Nutrient availability should be high in the Wolf Creek areas <br />and somewhat lower in the Wadge overburden areas. Lime or a <br />6-33 Revised 10/1/86 <br />