"December, 1971." Includes bibliographical references (pages 167-171).

Analysis of exploratory test cores and rock chip samples has made available information necessary to the development of rational techniques for reclaiming coal mine spoil for useful purposes. By assigning an area a particular future use and analyzing the rock structure in advance of the surface mining, materials can be assembled and placed in the fill to allow the filled strip mine to revegetate and be developed into a useful area. Oxidation of pyrite materials, source of most acidity below 4.0 in mine spoils, can be controlled by: (1) using clay shales for fill; (2) controlling gain size in the fill; and (3) controlling accessibility to exchange of solutes and oxygen. In miniature lysimeters filled with 4 ft of normal, loamy (pH 6.7) soil, no acidity nor iron drained from the bottom from pyrite buried at 6 depths, from 1/2 to 36 inches, during a 24 week test period. Base exchange by the soil neutralized the acid and retained the iron.