2010-12-17_REVISION - C1981019 (142)

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Baseline Survey of Soil Resources - Collom Mining Area July, 2006 The use of this soil is limited by the high clay and coarse fragment content present throughout the profile. Salvage operations will be limited by the shallow depth to bedrock with very little opportunity to separate topsoil from salvageable subsoil. Campspass Clay and Clay Loam The Campspass series primarily consists of deep, well-drained soils that formed primarily from weathered shale with some thin loess influence in the surface horizons. Shallow and skeletal variants of this series occur in isolated sections of ridge crests where sandstone and shale are present within 30 inches of the soil surface. Taxadjuncts include fine loamy soils with characteristics comparable to Campspass. The primary limiting characteristics of this series are the high clay content (generally well over 50 percent) and low nutrient levels. The lower extent of the most suitable soils is marked by the presence of carbonates and a dramatic increase in clay, coarse fragments and occasionally bedrock contact. Cochetopa Clay Loam The Cochetopa series consists of deep, well-drained soils that formed in colluvium derived from shale and siltstone, often with loess influence within the top 10 inches. The series is found on hills and valley sides in the southern portion of the Survey Area. Taxadjuncts include soils with high coarse fragment content in the subsoil (often over 35 percent channers). Variants include similar Palecryolls with argillic horizons beginning 24 inches or more below the soil surface. The primary limiting factors of this soil are high clay content (30 to 40 percent) and high coarse fragment content found deep in the subsoil. The nutrient levels of this soil are generally high for the Survey Area and are comparable to other Cryolls (mollisols with a cryic temperature regime). Danavore Channery & Gravelly Clay Loam The Danavore series consists of moderately deep, well-drained soils formed in colluvium and slope alluvium derived from interbedded sandstone and shale. This series is found on valley walls and convex C slopes throughout the southern portion of the Survey Area. Coarse fragment content dramatically increases below the first 10 to 20 inches of soil and can range from 50 to 90 percent. While the depth of salvage is limited, the nutrient content of the subsoil is good for the area, and actually higher than the topsoil for the sites sampled. Duffymont Shallow Loam The Duffymont series consists of very shallow or shallow, well- to somewhat excessively-drained soils formed in slope alluvium and colluvium over sandstone bedrock. These soils are found on the plateaus in the center of the Survey Area and more commonly occur near the canyon slopes. This soil is limited by the presence of bedrock at depths ranging from six to 20 inches. The soil available for salvage is loamy and has high nutrient levels. Evanot Loam The Evanot series consists of very deep, well-drained soils that formed in aeolian deposits and slope alluvium. Evanot soils occur to a very limited extent in the Survey Area and are found on north facing slopes in the northern portion of the Survey Area. The shade and wind shelter provided by the slopes allow the soils to retain more moisture than surrounding units (i.e., ustic vs. aridic moisture regime). This series is comparable to the Morapos series and has few limitations, within the developed profile. The most suitable soil is generally found within the top 40 inches and ends where a noticeable increase in coarse fragment or carbonate content begins. Forelle Loam The Forelle series consists of deep, well drained soils on fan aprons, fan piedmonts, hillslopes, and hill toeslopes in the extreme northern portion of the Survey Area. The Forelle series is primarily limited by the very low nutrient content and high level of carbonates in the subsoil relative to other soils in the Survey Area. The subsoil also occasionally has clay content in the subsoil at percentages high enough to limit potential reclamation uses. Variants to the typical series include soils with paralithic contact within 40 inches of the soil surface. The soil is found in close association with the finer textured Pinelli series. • Tetra Tech, Inc.