2018-04-02_PERMIT FILE - C1981019A (7)

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RULE 2 PERMITS Soil organic matter is a critical source of nutrients in native soils and often accounts for low free nutrient levels. Soil organic matter ranged from to 0.3 to 9.6 percent and averaged 3.13 percent. The Aridisols and Entisols exhibited the lowest organic matter content, while the pachic mollisols, Rhone, Lamphier, and Cochetopa series had the highest content. Boron and Selenium Concerns over boron and selenium content in mine soils prompted testing of background levels in the Soils Survey Area. The soils tested revealed boron concentrations ranging from 0.07 to 1.34 parts per million (ppm) and averaging 0.39 ppm. Selenium levels range from less than 0.02 to 1.0 ppm with most registering below the detection limit. These results do not support the need for further analysis, as it appears boron and selenium are found in low concentrations in the parent materials of the Soils Survey Area. There appears to be few chemical or physical limitations for salvage and use of soils for reclamation with the exception of high clay content and high coarse fragment content. The primary chemical property limiting salvage is nutrient content. Each soil horizon was determined to be suitable or unsuitable. The weighted average depth of suitable soil was then calculated for each map unit based on the suitable depth of each soil series multiplied by the percentage of the map unit which it comprises (Table 2.04.9-16). Following the development in any one five-year mine area the amount of soil salvage will be assessed to determine the need for assessing potential substitute soil sources. The distribution and extent of map units in the survey areas are presented on Map 513. The maps were compiled on a topographic map base at a scale of 1"=500'. The soils maps contain a map unit legend and all map unit delineation lines. Soil pedon description/sample sites are also located on the maps. The soil delineations have been digitized into the electronic file for map display and acreage determination by map unit. A summary of various map unit descriptive information is presented in Table 2.04.6-20. The information for each map unit includes: ■ Map unit symbols ■ Slope ranges ■ Soil series name and map unit symbol • Map unit components and percentages of each soil type ■ Surface textures ■ Topsoil and subsoil salvage depths ■ Salvage limiting factors ■ Soil inclusions ■ Brief soil discussion Soils interpretative information presented in Exhibit 9, Item 8 includes detailed information regarding each soil series and other soil families. Information in the Baseline Soil Survey includes: ■ Soil series name and map unit symbol ■ Texture of the soil control section ■ Soil depth class ■ Physiographic position Collom — Rule 2, Page 40 Revision Date: 12/30/16 Revision No.: TR -108