Laserfiche WebLink
2.0 New Horizon 2 Overburden and Interburden Characteristics <br />Overburden and interburden characteristics for New Horizon 2 are presented in Section 2.04.6, <br />Geology Description. Overburden and interburden suitability and lithologic units for the New <br />Horizon #2 Mine described in Section 2.04.6 are very similar to the shallow overburden units at <br />the New Horizon #1 Mine area. The only significant difference between mine areas is the mean <br />thickness of Unit 1 (Bench 1) which averages 5 feet at New Horizon #1 Mine compared to <br />about 55 feet within the New Horizon #2 permit area. Approximately 83 percent of the <br />overburden and interburden material at New Horizon 2, consisting predominantly of Units <br />1(Bench 1) and 3, is classified as suitable for root growth and aquifer medium material (Section <br />2.04.6). Unsuitable material was identified in the lower overburden and interburden (Units 2 <br />and 4) within the proposed disturbance area (Peabody, Appendix 6 -5). <br />3.0 Acid and Toxic - Forming Materials at New Horizon 2 Mine <br />Acid and toxic - forming materials were identified within the New Horizon 2 study area; however, <br />only the acid - forming material occurs within the projected mining disturbance area (Peabody <br />Appendix 6 -5 and Map 2.04.6 -1, Geologic Cross Section and Sample Locations for New <br />Horizon 2 Study Area). Therefore, some ameliorating activity such as mixing, normal burial, or <br />special handling will be required to replace a suitable four -foot root growth medium and to <br />prevent leachates and runoff from entering the ground water system or discharging into the <br />surface water system. No roads will be surfaced with the acid - forming material. Mitigation of all <br />unsuitable zones within the underburden material (five percent of all unsuitable zones which <br />were identified) will be by avoidance, i.e., these zones will not be disturbed by mining activities. <br />Certain areas of overburden and interburden will also be avoided due to the projected <br />disturbance area boundary described within this application (Map 2.05.3 -1, Current Mine Plan - <br />New Horizon 2) or excessive Dakota coal seam depths. These additional avoided areas <br />comprise about 60 to 65 percent of all unsuitable zones which were identified. <br />Complete mixing of the thicker, calcareous overburden Unit 1 or Bench 1 (30.5 feet) and <br />interburden Unit 3 (6.7 feet) with the thinner, acidic overburden /interburden Units 2 (4.5 feet) <br />Revised September 2010 (PR 06) 2.05.4(2)(d) -2 <br />