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• LITERATURE REVIEW REGARDING WESTERN COAL REFUSE <br />MATERIALS <br />Relatively less reclamation research in the West has been conducted <br />specfically on coal refuse materials than on regraded mine spoils as a whole, <br />however, sufficient similarities exist between the properties of the two that the <br />existing research can be used to draw a number of conclusions. <br />Berg (1971) appears to have been among the first to initiate studies aimed <br />at the characterization and revegetation of coal mine refuse materials in <br />Colorado. Working at a site at Morley, Colorado located 10 mines south of <br />Trinidad, Colorado on refuse materials deposited several decades earlier the <br />refuse was reported to have a near neutral pH, ranging from a low of 6.6 to <br />a high of 7.1 with a mean of 6.9. The electrical conductivities were all below <br />0.55 mmhos/cm and the textures were all reported to be gravelly sandy clay <br />loams. First year surv'roal of seven species of shrubs and trees was reported <br />to average 85 percent for the deciduous shrubs and 97 percent for the <br />con'rfers. <br />To the west of Trinidad, Colorado, the refuse materials at the old CF & I, <br />Allen Mine, now called the New Elk Mine, were studied by Colorado State <br />University in extensive research conducted between 1976 and 1980 on coal <br />refuse that was approximately 15 to 20 years old. Pretreatment sampling of <br />these materials revealed that these materials were sodic, the SAR averaged <br />• 32 and values ranged between 15 and 36, suggestive of very adverse <br />growing conditions. Due to the high sodicity, gypsum was applied as a <br />chemical amendment. Additional treatments included various mulches, <br />fertilizers and soil combinations. At the conclusion of the third growing <br />season Abbott (1981) reported that the application of gypsum produced no <br />difference in 'seeded grass, forb, and or shrub density cover or biomass.' <br />He reported that the plots treated with gypsum 'appeared to have a lower <br />plant vigor' as compared to the untreated plots. The lack of response to the <br />gypsum treatments was attributed to "insufficient water entering the coal <br />waste to sotubilize the gypsum.' Wdh respect to sodium he stated that "plant <br />growth did not appear to have been strongly affected by the presence of Na.' <br />Fourth year revegetation results for this study site were reported by Fimbel <br />(1982). Fimbel reported that the gypsum amendment "did not greatly <br />influence plant growth and should not be included in a large-scale <br />reclamation program° on coal waste material. Possible explanations for the <br />lack of response to gypsum in ameliorating sodicity was attributed to 1) SAR <br />probably overestimated the sodicity hazard, 2) the coarse nature of the spoils <br />mitigated any dispersion by sodium, and 3) the presence of appreciable <br />amounts of pyrites and/or gypsum existing in the shales countered the <br />negative effects of sodium. Of interest is that Fimbel reported that plant cover <br />and biomass values demonstrated steady increases in growth each <br />successive year the plots were monkored. <br />These data suggest that the presence of elevated sodium levels in these <br />• coal waste materials did not adversely affect plant growth as have been <br />documented in various revegetation efforts on much heavier textured spoil <br />materials in the Northern Great Plains. A comparison of the soils data <br />collected by CSU initially in 1976 and again in 1980 demonstrate that <br />signficant changes as measured by the "t-test statistic' occurred during the <br />3 <br />