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• published research on reasonable threshold limits. Kerr is proposing an <br />arbitrary suitability limit of 20 for ESP, with this value falling within <br />the range of reasonable threshold limits identified by the research. <br />If potential suitability concerns are confirmed by preliminary and <br />supplemental sampling, Kerr will have the option of either replacing or <br />covering the potentially deleterious materials to achieve a minimum cover <br />of 4 feet of suitable material. <br />The soil sampling program will follow that recommended by Follett and Heil <br />(1966) and USDA-SCS (1972). Sample spacing will be the same as designated <br />for spoil sampling with sampling depth corresponding to the soil <br />replacement depth. Composite samples will be taken as recommended by Berg <br />(1978) to accurately determine suitability and the range of soil nutrients <br />in the reapplied topsoil at both the Kerr Mine Area and the Kerr Tipple <br />Area. Samples will be analyzed according to the methods suggested by <br />Sandoval and Power (1978) relative to western mine soil analysis. Topsoil <br />suitability will be evaluated with respect to the limits defined in WDEQ <br />Guideline No. 1, Topsoil and Overburden. Potential topsoil sodicity <br />concerns will be evaluated with respect to SAR as a measure of equilibrium <br />conditions. <br />Specific fertility parameters to be sampled will be: plant available <br />nitrogen reported as ppm nitrate-nitrogen; organic matter will be sampled <br />to determine the nitrogen producing potential from that material; and <br />phosphorus levels will be analyzed and reported as ppm plant available <br />phosphorus in the soil. Other plant essential nutrients described in <br />Sultanpour, et. al. (1985) will not be analyzed because all soil analyses <br />(Section 779.21) and overburden analyses (Section 779.14) collected to <br />date on the proposed permit area show adequate amounts of copper, zinc, <br />iron, and potassium. Therefore, only the plant nutrients of nitrogen and <br />phosphorus have the potential of being deficient the soil. Nutrient <br />levels will be evaluated using the approach and criteria recommended in <br />"Guide to Fertilizer Recommendations in Colorado - Soil Analysis Computer <br />Process, (Soltanpour et al, 1985). Specifically, recommendations for <br />dryland native grass sites will be utilized for the Kerr mine and loadout <br />areas. <br />780-72Ra <br />Revised -October, 1990 <br />