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ATTACHMENT6 ~~ Evaluation of Topsoil and Overburden Materials in the Lease Area 1. Introduction This evaluation has been made by agreement with Stearns-Roger, Inc., Denver, Colorado, for Utah International, Inc., San Francisco, California. The plan For the lease area is to supply coal by strip mining operations. The distuubed area will be reclaimed concurrently with mining. UII needs information on the nature and suitability of the overburden materials as a medium for plants in order to prepare revegetation plans and put them into practice later as needed. UII desires an evaluation of the topsoil presently coveting the lease area in order to plan possible future uses of this topsoil in connection with a feasible reclamation program for revegetating the disturbed area. This report will assist UII in formulating these plans. Procedures for collecting and dividing the overburden samples from drill cores are indicated in the attached letter of April 5, 1973, to Mr. G. W. Smedes, Stearns-Roger, Inc., from Mr. Lawrence Tisdel, Colorado School of Mines Research Institute, Golden, Colorado. CS:~[RI conducted chemical and physical tests on the overburden and topsoil samples. These results are reported in the section "Laboratory Data" in tables 1 to 6. This report evaluates the chemical and physical properties of the overburden samples in connection with their predicted suitability for plant growth. Interpretive comments are made concerning likely problems that may be encountered in plans to utilize the overburden material directly as a medium for plant growth. The overburden material in same portions of the lease area, however, appears to be suitable as a medium for plant growth if accompanied by adequate fertilizer nutrient additions and by mixing of layers and proper grading. This report also examines the effect of artificial weathering, induced by freeze-thaw cycles, on the physical and chemical properties of selected samples of the overburden. The effect of these changes on expected plant growth is indicated. 2. Evaluation of Topsoil 2.1 A description of [he soils and vegetation in the lease area is given in Section 2 of the Environmental Analysis. A map outlining four major kinds of soils is shown as Figure 2.3. 2.2 Chemical properties In general the chemical properties of the areas covered by loess (wind blown deposits) are most favorable for producing fertile soils in their present virgin state. Nitrogen and phosphorus fertilizer would make all of the topsoil higfily productive although certain areas are presently well supplied with these nutrients. Chemical analyses are shown in table 1. The numbers identifying the soil samples under Column 2, table 1, correspond to sample sites selected for the drill holes for overburden samples, but some additional sample sites were selected that are referred to by direc- tion From a drill hole site. 7