2016-12-23_PERMIT FILE - C1982056A (8)

Home Browse Search

25 percent slopes, map units 68C and 68D. Soil cores #7 and 8 were mapped as Aaberg silty clay, 25-65% slopes, map unit 35F. In Section 17, soil cores #10, 11 and 12 were located within the Binco silty clay loam, 3-25 percent slopes, map units C10 and D10. A narrow inclusion of Cumulic Cryaquoll soil was observed in the small drainage channel bisecting the ventilation pad area in Section 17 (Map 2S). Maximum rooting depth at soil core #2 (Cumulic Cryaquoll) was observed into the seasonal high water table. Soil mottling within the soil profile is a good indication of the depth of the seasonal high water table that can fluctuate with the season and by year. Enhanced vegetation growth and plant species adapted to mesic and riparian sites was also evident adjacent to soil core #2. Unconsolidated stream -laid sediments were observed at 25 inches and exhibited free water within these unconsolidated gravels and coarse sands. Similar soil characteristics were observed in the small drainage channel bisecting the ventilation pad area in Section 17 (Map 2S). The maximum rooting depth at soil core #9 (Menbar series) was observed to a depth of 47 inches with a significant decline in roots noted at shallower depths due to calcareous root restricting horizons. Unconsolidated stream -laid sediments were observed below 105 inches and exhibited free water within these unconsolidated gravels and coarse sands, however, no indicators of AVF soil characteristics were evident in this soil core within the rooting zone. While this colluvial material may overlay water -bearing unconsolidated alluvial strata, these colluvial materials are at a sufficient depth and contain shallow, calcareous root restricting horizons that prevent any subirrigation potential. Reduced vegetation growth and production at this sampling site were evident from the plant species that are more adapted to semi -arid, non -sub -irrigated sites. The field survey observed a distinct soil, vegetation, and topographic boundary between the AVF and the upland portion of the study area containing the proposed ventilation shaft facility access road. Soil core descriptions, surface vegetation, and topographic relief indicate that the existing AVF boundary (as previously defined in Exhibits 7b, 42a, and 46) along Fish Creek in Section 11 should be relocated as shown on Map IS. Approximately 800 feet of proposed road corridor in Section 11 has been relocated upgradient approximately 100 feet to follow an existing abandoned farmstead access road and avoid potential wetland soils along the stock pond shoreline. The remaining 6,314 feet of access road corridor from the fenceline at the south end of the stock pond to the shaft pad have no soil limitations. Soil coring and geologic stratigraphy strongly suggest that the entire ventilation shaft pad is located on a suitable upland Winevada soil series formed over fractured sandstone bedrock parent material. While the previous AVF boundary (shown in green on Map IS) is located within the southwest corer of the shaft pad, the revised AVF boundary (shown in red on Map 1S) lies outside of the proposed shaft pad location. Southern and western portions of the 500 -foot buffer that overlay the Fish Creek channel contain AVF and wetland soils (Map IS). No soil mapping activities were performed on the west side of the railroad corridor within the 500 -foot buffer area since pad and shaft construction activities will not cross the railroad tracks. As construction activities are limited to the ventilation pad and northern and eastern halves of the buffer area, no AVF or wetland soils will be affected. The 9 -East Utility Borehole project area is immediately adjacent and to the south of the 18 -Left Ventilation Shaft Road. Previous soil mapping did not include this area, so the most recent soil mapping (NRCS, 2006) and soil descriptions for this area was obtained and reviewed. The soil types to be affected by disturbance are similar to those for the nearby 18 -Right Vent Shaft disturbance (as discussed above), and include the Rabbitears loam, 3 to 12 percent slopes (68C), and 12 to 25 percent slopes (68D), and the Winevada-Splitro complex, 3 to 25 percent slopes (X8D). Soil depths (A and B1 horizons to gravel or clay) range up to 26 -inches (68C), 22 -inches (68D), and 38 - inches (X81)), respectively. The site-specific soil mapping and soil descriptions have been added as Exhibit 16C, Appendix 4, for reference. MR16-296 2.04-50.2 05/10/16