2010-12-17_REVISION - C1981019 (142)

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Baseline Survey of Soil Resources - Collom Mining Area July, 2006 Additional parameters were analyzed in accordance with the following protocol: Fertility _(Organic Matter Content, Nitrogen Phosphorus and Potassium : The following horizons from all sample sites were analyzed for soil fertility: ? All A horizons; ? All B and C horizons beginning within 24 inches of the ground surface; and, ? Those B and C horizons with less than 35% clay and less than 35% coarse fragments. Boron and Selenium: Boron and selenium were not known to be present in elevated concentrations in the Survey Area. However, to provide information for screening, the thickest horizon beginning within the top 24 inches of the soil profile was analyzed for these parameters. Soil Map Unit Development Preliminary map unit boundaries were identified in the field where supported by available data and site inspection. Boundaries of preliminary map units were further refined based on the results of pedon descriptions and development of conceptual map units. Many of the conceptual map units were documented in the field for further refinement based on review of all available information, including laboratory results and final pedon classifications. Following completion of the field effort, two significant resources became available to further assist in map unit refinement. The first of these resources was a new high-resolution, color satellite image with a false- color infrared display. This image revealed more detail related to vegetation communities, outcrop patterns, and early fall soil moisture levels. The second resource was development of hillshade models to simulate the accumulation of loess deposits in the Survey Area. This simple tool visually simulates those j areas most likely to accumulate loess with various prevailing winds. In combination with one another, these resources dramatically improved the accuracy and precision of the survey. Each map unit within the Survey Area was described by documenting soil series and families found in the map unit, their relative composition, and their placement relative to one another. Map units produced as part of this survey were composed primarily of consociations and complexes, with the smallest units approximately 0.5 acres in size. RESULTS Pedon Descriptions Pedon description forms for each of the 456 sites observed in the Survey Area are presented in Appendix A. These forms were updated with the results of laboratory analysis, where available, and classified first to the family level and then correlated to series identified as major components of NRCS map units within five miles of the Survey Area. The pedon classifications yielded 53 unique textural families, including thirty series and 23 families with no corresponding series identified in nearby portions of the NRCS surveys. The series identified, along with variants and taxadjuncts, represented 393 of the 456 pedons (86 percent) described in the Order II Survey Area. Identifying the correct soil temperature and moisture regime is critical to determining the correct classification in accordance with the current Keys to Soil Taxonomy (USDA, 2006). In-depth review of the NRCS survey of Moffat County (USDA 2005a) revealed significant changes in the soil temperature and moisture regimes within the Survey Area. Onsite evaluation of soil and vegetation and discussions with Charles Peacock, soil scientist in the Craig, Colorado, NRCS soil survey office (Charles Peacock personal communication with Judd Stark), confirmed that the major regime changes do exist and provided insight into the likely patterns. i Tetra Tech, Inc. 3