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Completion_of_reclamation_at_the_Gregg_River_Mine__Alberta

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					Completion of Reclamation of the Gregg River Mine, Alberta
David Brand

Hinton, Alberta Canada

In May of 2000, the decision to close the Gregg       Act. The fundamental tenet of the Environmental
River Mine was announced. A combination of            Protection and Enhancement Act (EPEA) and its
low international metallurgical coal prices and       Conservation and Reclamation Regulation is
adverse geologic conditions contributed to the        stated as; ‘The objective of conservation and
closure. Mine construction began in 1981 with         reclamation is to return specified land to an
coal production following in 1983. With the           equivalent land capability’. The focus of the
announcement of the closure, operations at the        reclamation activities at GRM is to return the
mine switched entirely to reclamation.                land back to the crown in a state that is
                                                      equivalent to the original landscape, but not
The Gregg River Mine (GRM) is situated in west        necessarily identical.
central Alberta, approximately 40-km southwest
of the Town of Hinton. Located in the foothills       The End Land Use plan for the mine was
of the Rocky Mountains, elevations range from         approved in 2000 and detailed a significantly
1400 m to near tree line at 2000 m. The mine is       different approach to reclaiming the landscape. A
in the Upper Foothills Natural Region, with           method of matching the physical characteristics
vegetation characterized by late succession,          of the site to the vegetation community best
mature lodgepole pine, white or engelmann             suited to the combination of slope, aspect and
spruce and alpine fir. Soils are generally thin       soils was developed. Reclaimed areas of similar
and rocky. The climate is severely influenced by      characteristics were grouped together and termed
the mountains and the elevation; snow is              Ecological Reclamation Units (ERU’s). Specific
common in all months of the year, including           soil replacement and vegetation plans were
August. Strong chinook winds blow in the              developed for each ERU in an attempt to match
winter, melting and moving snow and creating a        appropriate reclamation treatment to the
very difficult growing environment for plants         biophysical aspects of the landscape. The ERU
and young seedlings.                                  method was proposed in an attempt to reduce the
                                                      significant effect the strong chinook winds have
Mining at GRM utilized traditional truck and          on vegetation. The primary end land use for
shovel mining methods, with 190 tonne trucks          GRM was identified as being wildlife habitat and
hauling drilled and blasted rock loaded by            watershed protection recognizing the fact that
electric and diesel shovels to waste dumps. As        there was no potential for commercial timber
mining progressed the waste was also used to          prior to mining taking place.
backfill pits where the mining had been
completed. During the life of the mine, over 350      Sloping the spoil and rough dumped material is
million tonnes of rock was moved to produce 45        the first step in the reclamation process and
million tonnes of coal. The mine employed up to       incorporates about half the cost associated with
460 employees at peak production. A total area        reclaim activities. Caterpillar D10N dozers and
of 1351 hectares had been disturbed at the time       backhoes are too used reduce the slope angle of
of the closure of the mine, with the plant site and   the disturbance to less than 27 degrees. Two of
other infrastructure comprising 61 hectares of        the goals that were established for sloping were
disturbance. Of those 1351 hectares, 346 were         to create a smooth interface between the
reclaimed during mining.                              undisturbed and reclaimed landscape and to
                                                      avoid the concentration of runoff water and the
Coal mining in Alberta is regulated by the            resulting erosion. Additional considerations were
environmental legislation of the Water Act, the       to provide broken site lines in the landscape to
Environmental Protection and Enhancement Act          protect ungulates from predators and to provide
and to a lesser degree the Public Lands Act and       as diverse and natural a landscape as practical.
the Coal Conservation Act. Development of the
coal resource is governed by the Coal                 Following sloping, a reclaimed soil profile must
Conservation Act and the Mines and Minerals           be established. Originally, the regulators required
that regolith or subsoil be placed on mine spoil.      associated valley fills, relocation of two creek
Testing of the sloped spoil material revealed that     beds, and the removal of ten waste water control
the composition of the regolith being placed on        structures. Since 2000 over 700 hectares of mine
the spoil was largely the same as the spoil            land have been sloped, the surface soil replaced
material itself. Presently the spoil is sampled        and seeded. Four years of concentrated
after sloping, with regolith only being applied        reclamation effort has seen many changes in
when the spoil falls outside the specified regolith    approach, focus and methods as compared to the
criteria. Topsoil from stockpiles of previously        reclamation completed at the mine in the early
salvaged material is then placed on the                1980's. Recently the wildlife at the mine site has
recontoured slope. The most serious limitation to      included the return of the predator species that
successful plant growth, aside from topsoil            were largely absent during mining. In the past
quality, has been found to be soil compaction. In      year sightings of grizzly and black bears and
order to minimize soil compaction, the soil is         wolves feeding on ungulate kills have been
placed as roughly as possible while still              common indicating the start of a return to
obtaining the required topsoil depths. Where           nature’s natural balance. Watching the results of
possible, placing the topsoil by casting with a        the Gregg River Mine reclamation work should
backhoe has been found to be very effective.           provide many more opportunities to further
Travel over topsoiled surfaces with equipment is       improve practices and optimize results.
avoided. The less compacted ground surface has
the added benefit of collecting little surface
water minimizing erosion.

The final step in the reclamation process is the
seeding followed by tree planting where
required. Traditionally seeding at the mine site
was done with a heavy application of seed and
fertilizer to stabilize the soil quickly and prevent
erosion. This provided a very thick mat of green
that was found to be aesthetically pleasing but it
did create some other problems in re-establishing
trees. The thick grasses and legumes combined
with the harsh climate created huge obstacles to
seedling survival. In response to these problems
our seed mixtures have been modified to include
more native and fewer agronomic species and a
lower application rate. A similar approach has
been used with fertilizer, reducing nitrogen input
and overall application rate. When possible trees
are planted the season following the seeding
giving them a chance to become established
before the vegetation becomes too heavy. The
twin results of these changes are more successful
tree re-establishment and more natural
colonization of native species. The second major
obstacle to successfully growing trees has been
the browsing of bighorn sheep, elk and mule
deer. Our success at creating wildlife habitat has
created new problems in reforesting the mine
site. At present we are adjusting species we are
planting, increasing less palatable species and
planting mixed stands of the more palatable
ones. By mixing the species, the survival rate of
the preferred browse species increases
considerably as compared to unmixed stands.

At present the reclamation of the Gregg River
Mine is largely completed. Some of the more
noteworthy projects completed include the
removal of two major stream crossings and

				
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posted:10/5/2011
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