2010-12-30_PERMIT FILE - P2010026 (5)

Home Browse Search

3.2.2 FRAGILE SOILS Several soils within the study area are considered fragile. They are considered fragile when they meet any of the following criteria: • Areas rated as highly or severely erodible by wind or water, as listed by NRCS Highly Erodible Land (HEL) soil map units • Areas with slopes greater than 35 percent, if they have one of the following soil characteristics: (1) surface texture that is sand, loamy sand, very fine sandy loam, fine sandy loam, silty clay, or clay, (2) depth to bedrock that is less than 20 inches, (3) an erosion condition that is rated as poor, or (4) an erosion potential "K" Factor of greater than 0.32. Four of the six soil map units (map units 64, 70, 73, and 75) are listed by NRCS as meeting Highly Erodible Land criteria for severe wind erosion hazard and water erosion hazard. These map units include three soil series: Piceance, Redcreek, and Rentsac (Sanders, 2009). 3.3 SOIL SUITABILITY AND RECOMMENDED SALVAGE DEPTH All soils are suitable for use in reclamation. None of the soils are sodic or saline. In general, reactions are moderately alkaline throughout the study area and may result in reduced plant growth; however, this reaction is common in northwest Colorado. Organic matter content is generally low, but is sufficient for plant growth and typical for the area, given the climate and biomass. Detailed interpretations and recommendations of the soil laboratory analyses from the CSU Soil & Water Plant Testing Laboratory are included in Appendix 1- Soils Laboratory Results. A discussion of soil suitability and recommended salvage depth for the individual soil map units are below: Map Unit 33: Forelle loam (Topsoil 12"/Subsoil 24") Forelle loam is entirely suitable for use in reclamation. The soil is nonsaline and nonsodic, and has suitable texture, coarse fragment content, and water holding capacity. Organic matter content ranges from 1.7 percent in the surface layer to 0.8 percent in the subsurface layer of the profile. Soil texture is loam. Forelle can be salvaged throughout its profile, an average depth of 36 inches or more in the study area. The upper 12 inches can be salvaged as topsoil, with the underlying 24 inches (from 12 to 36 inches) salvaged as subsoil. Map Unit 64: Piceance fine sandy loam (Topsoil 12"/Subsoil 18") Piceance fine sandy loam is entirely suitable for use in reclamation. The soil is nonsaline and nonsodic, and has suitable texture, coarse fragment content, and water holding capacity. Organic matter content ranges from 1.4 percent in the surface layer to 0.6 percent in the lowest part of the profile. Soil texture is fine sandy loam to loam. Piceance can be salvaged • throughout its profile to the bedrock contact, an average depth of 30 inches in the study area. 10