rM 



Figure 14.— Graded and seeded spoil blending into the natural wooded terrain at the Absalol<a mine in Montana. The chiseled, 

 rough surface will accumulate moisture during the winter for germination of the grass seed in the spring. In the foreground, 

 pine seedlings and native transplants were used to reintroduce the natural pine-grassland interface vegetation in this 

 region. Both containerized and bare-rooted seedlings were used. Bare-rooted plants had a lower survival rate. October 1978. 



the undesirable characteristics of the clayey 

 materials. 



The greatest technical challenge occurs vyhen 

 the entire overburden has a harmful character, 

 such as in the sodic clay sequences in the North 

 Dakota and adjacent Canadian lignite coalfields. 

 In some places in North Dakota, the salvage and 

 replacement of topsoil has been generally ef- 

 fective (Pole and others, 1979); in others, less so 

 (Sandoval and Gould, 1978, p. 500). No really 

 long-term sites exist, hov\/ever, that are diag- 

 nostic of the ultimate movement of sodium in 

 spoils. The use of plant species that are tolerant 

 to sodium-rich soils would not offer a complete 

 solution since plant diversity would be limited. 

 On most raw spoils there are few sources of 

 nutrients and little biological activity that makes 

 plant nutrients available. Nitrogen levels are also 

 low. Adding fertilizers is usually a short-term 

 solution, even though it may help plants become 

 established. In some cases, the annual plant 



debris do not decompose, and therefore 

 nutrients do not recycle into the soil. The addi- 

 tion of topsoil to the raw spoil would aid in the 

 reestablishment of soil micro-organisms whose 

 biological activity would return nitrogen to the 

 spoils. Thus, the Office of Surface Mining's 

 general requirement for topsoiling should help 

 to ensure reestablishment of the nutrient- 

 recycling that is necessary for revegetation and 

 soil development (Cundell, 1977, p. 301-303). 



TOXIC SUBSTANCES 



Although the uptake and concentration of 

 heavy metals or other potential toxicants by 

 plants may be detrimental to the plants and con- 

 sequently to the animals that feed on them, few- 

 confirmed examples of toxicity have been di- 

 rectly related to western coal mine spoils. Local- 

 ized abnormal concentrations of toxic or plant- 



29 



