Page 302 - Advances In Productive, Safe, and Responsible Coal Mining

278 Advances in Productive, Safe, and Responsible Coal Mining

into water sources as the postmining landform ages over multidecade time periods. An
aerial survey of a West Virginia mining complex, reclaimed using conventional
methods, found that slope distributions of postmining areas differed substantially from
those of premining landscapes [25].
Design of geomorphic-reclamation landforms entails estimation of landscape fea-
tures such as drainage-basin area, weighted mean slope, and drainage density of non-
mined areas; and construction of postmining landforms that mimic those features [26].
But replication of premining slope distributions is characteristic of the geomorphic
reclamation method. Construction of slopes with sigmoid profiles (convex-traight-
concave) as an alternative to linear slope designs can enhance land surface stability
[27]. Breaking long slopes with terraces and construction of stream channels with
meanders resembling natural landscape drainages can reduce down-slope water-
movement velocities and sediment-transport potentials.
The flow of water from highlands to oceans is an essential landscape process, and
natural stream channels are often excavated and/or filled by mining operations.
Hence, stream channel reconstruction is also an essential practice when conducting
geomorphic reclamation. Dimensions, patterns, and profiles of reconstructed stream
systems are determined by assessing essential features of natural, stable streams of the
region [28]. Construction of stable, natural-looking channels that mimic natural
stream forms on mined landscapes often requires strategic placement of stable rocks
to establish a channel base and produce pools and riffles. Restoration of premining
stream “functions,” such as organic matter processing, is often seen as a desirable
stream reconstruction outcome [29]. Recent research has found that establishment
of woody vegetation in the riparian areas of constructed streams, and creating soil con-
ditions that enable the woody vegetation’s survival and growth, can aid functional res-
toration in streams that are constructed at mine sites [30].

14.3.4 Mine-site preparation and initial excavation

As a first step of mine-site preparation, sediment control structures are established.
Water channels and ponds are constructed to manage water runoff from the disturbed
area. Sediment retention ponds are essential features, given that mines will expose
unvegetated soils and rock fragments that become subject to movement by rainfall
runoff. Retention times and hence volumes available for water retention are regulated
based on area and climate (e.g., in West Virginia the regulated retention capacity is
0.125 acre-foot of volume per acre of disturbed land). It is essential that ponds have
sufficient capacity to store runoff waters as needed and capture sediments so that dis-
charged waters will satisfy permit requirements.
Once sediment control structures are in place, timber (if present) is harvested. Soils,
vegetation, and posttimber harvest vegetative debris (if present) are removed to ini-
tiate the mining excavation. If the intended postmining land use involves natural eco-
system restoration, the soil and associated organic materials should be salvaged for
use in reclamation. When possible, salvaged soil and organic materials should be
moved to and placed in reclamation areas immediately; otherwise, they should be
stockpiled for later reclamation use. Prompt placement of soil and associated organic
materials can help to ensure that viable seeds, live roots, and soil animals (such as