Page 313 - Advances In Productive, Safe, and Responsible Coal Mining

Sustainable reclamation and water management practices 289

It is also possible to grow woody biofuel crops on reclaimed mine sites. Species
that have demonstrated good performance on Appalachian mined areas include wil-
low, hybrid poplar, American sycamore, and black locust [82–84]. Although hybrid
poplar grows well on some mine sites, it requires good soil drainage and repeated fer-
tilization; and its performance is hindered where those site conditions are not
achieved. Zipper et al. [59,62,84] reported rapid early growth of black locust on a Vir-
ginia mine site, but subsequent performance of those trees has been hindered by locust
leaf miners (Odontota dorsalis), an insect pest that commonly infests this species
throughout the area. One advantage of woody biofuel crops, relative to herbaceous
crops such as switchgrass or Miscanthus, is that woody crops can be grown on slopes
that would hinder operation of the agricultural equipment. Mined lands can be pre-
pared for woody biofuel crops using procedures described for forest establishment,
also previously covered. However, in contrast to native hardwoods, hybrid poplars
prefer soils in the range of 6.0–7.0 pH.

14.3.7.6 Developed land uses (industrial, commercial, residential)

Reclaimed mines are widely discussed as potential development sites, but modern rec-
lamation rarely prepares mined areas for building-support purposes. Surface stability
is a critical factor affecting suitability of reclaimed mines for industrial, commercial,
and residential development. Other important factors include the reclaimed mine
site’s access to water, utilities, and waste disposal.
Surface stability for the building development area can be achieved by using
common-sense procedures that are well supported by engineering practices.
A building development area (building support “pad”) should be located over flat
benches when possible, in an effort to avoid “differential settlement”—where the
depth of settlement varies under different parts of a structure—which can damage
buildings through structural distortion. The entire building support pad should be
placed in a well-drained location, as water saturation can stimulate settlement of even
well-compacted spoils, and its location should be surveyed so it can be located
precisely after reclamation is complete.
The pad should be constructed by placing spoil in lifts of controlled thickness and
composition, and should extend beyond the building’s perimeter by at least 3m in all
directions. Each lift should be constructed using a relatively uniform spoil material
that is compacted in place; the maximum size of rock fragments allowable in the
building pad should be determined through engineering calculations. Lift thicknesses
and degree of compaction should be determined based on engineering specifications
considering the nature of the spoil materials and the degree of stability required by the
postmining land use. For further details, see Zipper and Winter [85].

14.3.8 Revegetation and soil amendments
Once suitable materials have been placed on the surface and graded as needed for the
postmining land use, the soil can be prepared for seeding and revegetation. As stated
previously, the best material for use in mine-soil construction will usually include the