Laserfiche WebLink
suitable levels for site 873E and therefore were not determined on <br /> samples collected from sites 874E, 875E and 876E. <br /> The following parameters occasionally exceeded suitability levels and <br /> showed considerable variability across most lithologic units. <br /> Saturation percentage values ranged from 27 to 110 percent and, except <br /> for Unit 2 (upper Dakota Coal seam and surrounding very dark gray <br /> carbonaceous shale) , were suitable for all lithologic units. The mean <br /> saturation percentage of 72 percent recorded for Unit 2 was <br /> significantly higher than all other lithologic units (Table 6-15) . <br /> Salinity values were all suitable ranging from 0.6 to 8.3 mmhos/cm. <br /> Salinity values were slightly higher in Unit 2. Active acidity (pH) <br /> values ranged from 3.5 to 7.8. As shown in Table 6-10, the reaction <br /> values are neutral (7.2) for Unit 1, strongly acid (5.5) for Unit 3 and <br /> extremely acid (4.0, 3.9 and 4.3) for Units 2, 4 and 5. Similar <br /> potential acidity values were recorded for acid base potential (ABP) . <br /> The ABP values ranged from an excess of 192 to a deficiency of 40 tons <br /> of calcium carbonate per acre furrow slice. ABP values were highest in <br /> the overburden (Unit 1) and lowest in the upper Dakota Coal seam (Unit <br /> 2) . Mean ABP values were unsuitable for Units 2 (-11.9) and 4 (-5.6) . <br /> Except for one underburden sample from site 873E, all manganese <br /> concentrations were suitable ranging from 0. 1 to 14.3 ppm. These <br /> manganese levels are considered to be typical and adequate for normal <br /> plant growth (Barth et al . , 1981) . The underburden sample which had an <br /> unsuitable manganese ccicentration of 103 ppm, will not be disturbed by <br /> mining. Extractable iron concentrations were highly variable ranging <br /> from 1 to 686 ppm. Excessive levels (i .e. 300 ppm) were associated with <br /> the upper Dakota Coal seam (Unit 2) , lower interburden shale (Unit 4) <br /> and the underburden (Unit 5) . Although these levels may not necessarily <br /> be toxic, they may be high enough to cause appreciable nutrient <br /> imbalances (Barth , et al . , 1981) . <br /> Mitigative Measures for Unsuitable Material . Zones of unsuitable <br /> material were identified at each of the four Phase II sample locations <br /> and are documented by parameter, lithologic unit, location and sample <br /> 6-52 Revised 3/6/87 <br />