Whitewood mine
Encyclopedia
Whitewood is an Albertan
coal
mine located just north of Lake Wabamun
, about sixty-five kilometres west of Edmonton
, Alberta. Owned by the TransAlta Corporation
of Calgary
, the mine has been run by Luscar Ltd. (Edmonton) since that company acquired the extraction contract from Fording Coal Ltd. (Calgary) in 2003.
" model, harvesting approximately 2.8 megatonnes of sub-bituminous coal
per annum. Most of this thermal coal is used for steam-driven power generation
at the Wabamun, Sundance, and Keephills power plants, but a small amount of coal is sold to the residents of Parkland County for personal uses.
done there in the 1980s have allowed geologists
to establish the timeframe and geologic phases associated with the formation of the mine's coal bed. Analysis has shown that there are six distinct coal seams present at Whitewood, with deposits from the late Cretaceous
found at the deepest intervals, and with Early Tertiary formations found closest to the top.
A few layers of bentonitic
gangue
appear throughout the coal, most notably a three-metre seam near the uppermost portion of the late Cretaceous zone. Above the twenty to seventy metre thick coal-bearing deposit lies a glacial till
several metres deep; this must be removed from the surface before mining of the coal below can begin.
, with locales of forest
and wetland
interspersed throughout. The 2'800'000 tonnes of coal mined there each year act as enough fuel to fulfil approximately 13% of Alberta's electrical energy requirements. As a strip-surface mine, Whitewood employs the use of heavy equipment — excavators
, loaders/shovels, dumpers
, and the like — to extract the coal in an efficient and cost-sensible manner. Post-mining processing includes pulverisation, to maximise thermal yields when the coal is burnt in one of the surrounding power stations.
Although the present rate of extraction would allow this site's fifty-one million tonnes of reserves to be mined for more than a decade, TransAlta has plans to cease production by 2010, the same year the company will finalise the decommissioning of its coal-fired Wabamun electrical generation facility nearby. The company will continue mining coal at the massive Highvale mine five kilometres to the southwest; that mine produces 12.9 megatonnes of sub-bituminous coal per annum, has reserves pegged at over 200 megatonnes, and will be able to fuel the power plants now served by Whitewood, in addition to the Genesee power station.
process that follows. TransAlta has made provisions for renaturalisation to continue as far as 2013, three years after the Whitewood mine is slated to close. Already, the coal-depleted portions of the site have been subject to rebeautification, with pits being reclaimed as lakes
or being filled-in with backfill. Much of the backfill land is now lain with local subsoils
and rich topsoils
, which make the land suitable for agricultural
use; the other parts of the reclaimed land have been made into forests and wetlands
in a way that is designed to reflect the pre-mining environment.
When the mine is fully out of service, the power lines, service roads, sedimentation ponds, ditches, and other mining infrastructure will be removed, and their lands reconverted to their original forms. After the seeded vegitation takes root and grows, the mining site will hopefully show little evidence of having hosted a mine.
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
mine located just north of Lake Wabamun
Wabamun Lake
Wabamun Lake is one of the most heavily used lakes in Alberta, Canada. It lies west of Edmonton, Alberta. It is long and narrow, covers and is 11 meters deep at its deepest, with somewhat clear water....
, about sixty-five kilometres west of Edmonton
Edmonton
Edmonton is the capital of the Canadian province of Alberta and is the province's second-largest city. Edmonton is located on the North Saskatchewan River and is the centre of the Edmonton Capital Region, which is surrounded by the central region of the province.The city and its census...
, Alberta. Owned by the TransAlta Corporation
TransAlta
TransAlta Corporation is a power generation and wholesale marketing company headquartered in Calgary, Alberta.TransAlta maintains a low-to-moderate risk profile by operating a highly contracted portfolio of assets in Canada, the United States and Australia...
of Calgary
Calgary
Calgary is a city in the Province of Alberta, Canada. It is located in the south of the province, in an area of foothills and prairie, approximately east of the front ranges of the Canadian Rockies...
, the mine has been run by Luscar Ltd. (Edmonton) since that company acquired the extraction contract from Fording Coal Ltd. (Calgary) in 2003.
History
Opened in 1962, the Whitewood mine operates on a "stripSurface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...
" model, harvesting approximately 2.8 megatonnes of sub-bituminous coal
Sub-bituminous coal
Sub-bituminous coal is a type of coal whose properties range from those of lignite to those of bituminous coal and are used primarily as fuel for steam-electric power generation.- Properties:...
per annum. Most of this thermal coal is used for steam-driven power generation
Thermal power station
A thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this...
at the Wabamun, Sundance, and Keephills power plants, but a small amount of coal is sold to the residents of Parkland County for personal uses.
Geology
Development of the mining site at Whitewood and the seismic testingReflection seismology
Reflection seismology is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the Earth's subsurface from reflected seismic waves. The method requires a controlled seismic source of energy, such as dynamite/Tovex, a specialized air gun or a...
done there in the 1980s have allowed geologists
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
to establish the timeframe and geologic phases associated with the formation of the mine's coal bed. Analysis has shown that there are six distinct coal seams present at Whitewood, with deposits from the late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
found at the deepest intervals, and with Early Tertiary formations found closest to the top.
A few layers of bentonitic
Bentonite
Bentonite is an absorbent aluminium phyllosilicate, essentially impure clay consisting mostly of montmorillonite. There are different types of bentonite, each named after the respective dominant element, such as potassium , sodium , calcium , and aluminum . Experts debate a number of nomenclatorial...
gangue
Tailings
Tailings, also called mine dumps, slimes, tails, leach residue, or slickens, are the materials left over after the process of separating the valuable fraction from the uneconomic fraction of an ore...
appear throughout the coal, most notably a three-metre seam near the uppermost portion of the late Cretaceous zone. Above the twenty to seventy metre thick coal-bearing deposit lies a glacial till
Till
thumb|right|Closeup of glacial till. Note that the larger grains in the till are completely surrounded by the matrix of finer material , and this characteristic, known as matrix support, is diagnostic of till....
several metres deep; this must be removed from the surface before mining of the coal below can begin.
Coal extraction and uses
The Whitewood mine covers approximately 4700 hectares of slightly hilly prairiePrairie
Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...
, with locales of forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
and wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
interspersed throughout. The 2'800'000 tonnes of coal mined there each year act as enough fuel to fulfil approximately 13% of Alberta's electrical energy requirements. As a strip-surface mine, Whitewood employs the use of heavy equipment — excavators
Excavator
Excavators are heavy construction equipment consisting of a boom, stick, bucket and cab on a rotating platform . The house sits atop an undercarriage with tracks or wheels. A cable-operated excavator uses winches and steel ropes to accomplish the movements. They are a natural progression from the...
, loaders/shovels, dumpers
Dump truck
A dump truck is a truck used for transporting loose material for construction. A typical dump truck is equipped with a hydraulically operated open-box bed hinged at the rear, the front of which can be lifted up to allow the contents to be deposited on the ground behind the truck at the site of...
, and the like — to extract the coal in an efficient and cost-sensible manner. Post-mining processing includes pulverisation, to maximise thermal yields when the coal is burnt in one of the surrounding power stations.
Although the present rate of extraction would allow this site's fifty-one million tonnes of reserves to be mined for more than a decade, TransAlta has plans to cease production by 2010, the same year the company will finalise the decommissioning of its coal-fired Wabamun electrical generation facility nearby. The company will continue mining coal at the massive Highvale mine five kilometres to the southwest; that mine produces 12.9 megatonnes of sub-bituminous coal per annum, has reserves pegged at over 200 megatonnes, and will be able to fuel the power plants now served by Whitewood, in addition to the Genesee power station.
Environmental considerations
An important part of decommissioning a mine is the reclamationLand reclamation
Land reclamation, usually known as reclamation, is the process to create new land from sea or riverbeds. The land reclaimed is known as reclamation ground or landfill.- Habitation :...
process that follows. TransAlta has made provisions for renaturalisation to continue as far as 2013, three years after the Whitewood mine is slated to close. Already, the coal-depleted portions of the site have been subject to rebeautification, with pits being reclaimed as lakes
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
or being filled-in with backfill. Much of the backfill land is now lain with local subsoils
Subsoil
Subsoil, or substrata, is the layer of soil under the topsoil on the surface of the ground. The subsoil may include substances such as clay and/or sand that has only been partially broken down by air, sunlight, water, wind etc., to produce true soil...
and rich topsoils
Topsoil
Topsoil is the upper, outermost layer of soil, usually the top to . It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.-Importance:...
, which make the land suitable for agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
use; the other parts of the reclaimed land have been made into forests and wetlands
Constructed wetland
A constructed wetland or wetpark is an artificial wetland, marsh or swamp created as a new or restored habitat for native and migratory wildlife, for anthropogenic discharge such as wastewater, stormwater runoff, or sewage treatment, for land reclamation after mining, refineries, or other...
in a way that is designed to reflect the pre-mining environment.
When the mine is fully out of service, the power lines, service roads, sedimentation ponds, ditches, and other mining infrastructure will be removed, and their lands reconverted to their original forms. After the seeded vegitation takes root and grows, the mining site will hopefully show little evidence of having hosted a mine.