REP45090 - Laserfiche WebLink

Home Browse Search

• found to have OM values greater than 17.2 percent. All of the bench materials were found to have "suitable" OM levels. The two excursions were associated with the two uppermost coal seams in the overburden where OM V: values of 23.1 and 24.4 percent were found. It would appear that these ~R materials might potentially pose limitations on the revegetation where these materials are utilized, however, this is not believed to be the case. These two strata were found to have the highest nitrate nitrogen levels found for any of the materials sampled. Values of 4.9 and 12.1 mg/N03-N/kg were associated with these exposed coal seams. This enhancement in plant available nitrogen can be viewed as very positive with respect to revegetation and suggests that these carbonaceous materials may not follow the commonly assumed perception that coal is not a biologically active source of organic matter. Examination of the root growth in these two coal seams reveals that they contained a disproportionally greater concentration of roots than were found in any of the surrounding materials. Since these carbonaceous materials are documented as having greater nitrate nitrogen levels, which is very positive with respect to revegetation a's well as a greater rooting density than the surrounding non-carbonaceous materials, it appears that these materials and possibly the processed coal waste materials. placed into the refuse pile contain positive rather than negative amendment properties The two excursions above the Wyoming DEq suspect level for OC represent 1.995 percent of the total potential volume of overburden materials sampled. ~~ iven the fact that no other parameter suspect levels were exceeded, and that • these materials appear to exert positive rather than negative functions to the existing plants growing in this area, no problems are expected with respect to elevated OM values. It is also important to note that these carbonaceous zones are thin (1.1 and 2.8 feet thick), and that significant mixing will occur during salvage, replacement and regrading. The materials immediately adjacent to these high OM zones contain an average of 2.13 percent OM meaning that the necessary dilution rate to reduce OM below the suspect limit is only 33 percent. Given the mixing that will occur and the positive aspects of these high OM zones as described above, these materials possess a "suitable" ranking with respect to overburden quality ~ a ~ Rock Fragments. The Wyoming Guidelines report that materials having greater than 35 percent rock fragments are "unsuitable' as topsoil substitute materials. Examination of the existing soils information in the approved permit document reveals that 27 soils pits with notations on rock fragment content were dug in the immediate potential borrow area. These data found on pages 180 to 187, 195, and 206 to 207 of the existing Raton Creek Mine Permit document that in most stances the rock fragment content is quite high, usually between 10 and percent. Six of the 21 holes 'correlate to the immediate area sampled ~n this evaluation. Soil pits A1, A3 and A4 contain "channery" textural modifiers meaning that these soils contain between 15 and 35 percent channery rocks. Soil pits 5-6 and A2 contain less than 15 percent rocks as denoted by the absence of textural modifiers in the names. Of the remaining 21 soil pits, Soil Test Area III, pit ~ 4, Soil Test Area V, pits A6-A17, and Soil Test Area 1, pits 1-7, correspond to this • general area. Most of the notations regarding rock fragment content in the SCS soil pits relate to the stone and cobble size fractions and as a general rule, gravel content appears to be omitted. This is confirmed by correlating the soils mapped for this area with the soils mapping unit and profile descriptions for soil type PjF Louviers-Rombo-Travessilla Complex, 30 to 65 6