Open-pit mining , also known as open-cast or open-cut mining and in larger contexts mega-mining , is a surface mining technique that extracts rock or minerals from the earth.
63-454: The Berkeley Pit is a former open pit copper mine in the western United States , located in Butte, Montana . It is one mile (1.6 km) long by one-half mile (800 m) wide, with an approximate maximum depth of 1,780 feet (540 m). It is filled to a depth of about 900 feet (270 m) with water that is acidic (4.1 - 4.5 pH level ), about the acidity of beer or tomatoes. As
126-512: A black "grin patch". The colors are not as bright on the feet, legs, and bill of immature birds. The head can be stained rusty-brown from minerals in the soil where they feed. They are very vocal and can often be heard from more than a mile away. White- and blue-morph birds interbreed and the offspring may be of either morph. These two colors of geese were once thought to be separate species; since they interbreed and are found together throughout their ranges, they are now considered two color phases of
189-447: A mine that contribute to this load: drilling , blasting, loading, and hauling . Waste rock is hauled to a waste dump. Waste dumps can be piled at the surface of the active pit, or in previously mined pits. Leftover waste from processing the ore is called tailings , and is generally in the form of a slurry . This is pumped to a tailings dam or settling pond, where the water is reused or evaporated. Tailings dams can be toxic due to
252-569: A nearby creek and other local water sources. As a result, a water treatment plant has been operating at the site since October 2019. The Berkeley Pit can be visited by tourists, with a viewing stand and small visitor center. The underground Berkeley Mine was located on a prominent vein extending to the southeast from the main Anaconda vein system (sometimes called "the richest hill on earth"). When open pit mining operations began in July 1955, near
315-429: A number of worked-out mines. After mining ends at a location, the mine area may undergo land rehabilitation . Waste dumps are contoured to flatten them out, to further stabilize them. If the ore contains sulfides it is usually covered with a layer of clay to prevent ingress of rain and oxygen from the air, which can oxidize the sulfides to produce sulfuric acid , a phenomenon known as acid mine drainage . This
378-477: A result of room and pillar mining . Untopping removes the overburden from above this, opens up the mine from above, and then allows the previously 'trapped' minerals to be won. Untopping was a feature of Welsh slate workings in the 1930s and 2000s, where Martyn Williams-Ellis, manager at Llechwedd found that earlier Victorian workings could be kept profitable with the newly mechanised techniques for bulk excavation to extract their pillars, and more recently across
441-611: A result, the pit's water is laden with heavy metals and dissolved metals that leach from the rock in a natural process known as acid rock drainage . The dissolved metals include but are not limited to copper , arsenic , cadmium , zinc , and sulfuric acid . The mine was opened in 1955 and operated by the Anaconda Copper Mining Company , and later by the Atlantic Richfield Company (ARCO), until its closure on April, 22 in 1982. When
504-405: A result, waterfowl protection efforts were initiated. On November 28, 2016, upwards of 60,000 snow geese landed in the pit during inclement weather. Once discovered, officials made efforts to haze the birds off of the pit's water and prevent more from landing in the area. Three to four thousand of the geese died. An official report issued in 2017 by the U.S. Fish and Wildlife Service found that
567-429: A type of noise machine, and propane cannons that mimic gunshots are placed around the rim of the pit to keep birds from landing. When waterfowl do land on the surface of the pit, personnel use firearms, hand-held lasers, and unmanned craft to haze them. A protozoan species, Euglena mutabilis , was found to reside in the pit by Andrea A. Stierle and Donald B. Stierle, and the protozoans have been found to have adapted to
630-450: Is a crucial aspect of determining whether or not a geotechnical engineering design for open-pit slopes is attainable. Groundwater control systems, which include dewatering and depressurization wells, may also have a large impact on local groundwater. Because of this, an optimization-based version of the control system is required to ensure that local and regional hydro-geological impacts are within acceptable ranges. Open Pit depressurization
693-605: Is a rare vagrant to Europe , but escapes from collections have occurred, and it is an occasional feral breeder. Snow geese are visitors to the British Isles where they are seen regularly among flocks of brant , barnacle goose , and greater white-fronted goose . There is also a feral population in Scotland from which many vagrant birds in Britain seem to derive. Around 2015, a small group of 3-5 snow geese landed on
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#1732780533010756-585: Is a shallow depression lined with plant material and may be reused from year to year. After the female lays the first of three to five eggs, she lines the nest with down. The female incubates for 22 to 25 days, and the young leave the nest within a few hours of hatching. The young feed themselves, but are protected by both parents. After 42 to 50 days they can fly, but they remain with their family until they are two to three years old. Where snow geese and Ross's geese breed together, as at La Pérouse, they hybridize at times, and hybrids are fertile. Rare hybrids with
819-488: Is currently an active part of the remedy for this operable unit. A pilot water treatment project was initiated in 2019. It began treating and releasing Berkeley Pit water into Silver Bow Creek at the confluence with Blacktail Creek. This was done to protect the local groundwater from eventually becoming contaminated by rising pit water. The plant cost $ 19 million and was designed to treat ten million gallons of water per day. In 1996, 342 snow geese carcasses were recovered from
882-509: Is determined by the size of the equipment being used, generally 20–40 metres wide. Downward ramps are created to allow mining on a new level to begin. This new level will become progressively wider to form the new pit bottom. Most walls of the pit are generally mined on an angle less than vertical. Waste rock is stripped when the pit becomes deeper, therefore this angle is a safety precaution to prevent and minimize damage and danger from rock falls. However, this depends on how weathered and eroded
945-496: Is the sister species to Ross's goose ( Anser rossii ). Two subspecies are recognised: The greater snow goose is distinguished from the nominate form by being slightly larger. It nests farther north and east. The lesser snow goose can be found in two color phases , the normal white-colored animals and a dark gray-colored "blue" phase. The greater snow goose is rarely seen in a blue phase. The snow goose has two color plumage morphs , white (snow) or gray/blue (blue), thus
1008-401: Is the process of removing tensions or pressure from different areas of a mine. Depressurization helps to make open-pit mines more stable and secure. By using an integrated mine slope depressurization program the likelihood that mine plans can be achieved, and at an acceptable level of risk increase drastically. Depressurization allows considerable expansions of a mine, and can extend the life of
1071-559: Is then generally covered with soil , and vegetation is planted to help consolidate the material. Eventually this layer will erode, but it is generally hoped that the rate of leaching or acid will be slowed by the cover such that the environment can handle the load of acid and associated heavy metals. There are no long term studies on the success of these covers due to the relatively short time in which large-scale open-pit mining has existed. It may take hundreds to thousands of years for some waste dumps to become "acid neutral" and stop leaching to
1134-693: The Atlantic coastal plain . Traditionally, lesser snow geese wintered in coastal marsh areas where they used their short but strong bills to dig up the roots of marsh grasses for food. However, they have also since shifted inland towards agricultural areas, likely the cause behind the unsustainable population increase in the 20th century. This shift may help to contribute to increased goose survival rates, leading to overgrazing on tundra breeding grounds. In March 2015, 2,000 snow geese were killed in northern Idaho from an avian cholera epidemic while flying their spring migration to northern Canada . The snow goose
1197-668: The Lusatian Lake District , the Central German Lake District or the Upper Palatinate Lake District. A particular concern in the formation of these lakes is acid mine drainage . Open-pit mines create a significant amount of waste. Almost one million tons of ore and waste rock can move from the largest mines per day, and a couple thousand tons moved from small mines per day. There are generally four main operations in
1260-594: The Philippines and Indonesia . In 2024, nickel mining and processing was one of the main causes of deforestation in Indonesia . Open-pit cobalt mining has led to deforestation and habitat destruction in the Democratic Republic of Congo . Open-pit mines operating in an area with heavy groundwater features may eventually face hydrology-related problems. This includes heaving and bursting of
1323-483: The greater white-fronted goose , Canada goose , and cackling goose have been observed. Snow geese breed from late May to mid-August, but they leave their nesting areas and spend more than half the year on their migration to-and-from warmer wintering areas. During spring migration (the reverse migration), large flocks of snow geese fly very high and migrate in large numbers along narrow corridors, more than 3,000 mi (4,800 km) from traditional wintering areas to
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#17327805330101386-418: The mineral resource is exhausted, or an increasing ratio of overburden to ore makes further mining uneconomic. After open-pit mines are closed, they are sometimes converted to landfills for disposal of solid waste. Some form of water control is usually required to keep the mine pit from becoming a lake. Several former open-pit mines have been deliberately converted into artificial lakes, forming areas such as
1449-579: The "gray goose" genus Anser . Snow geese breed north of the timberline in Greenland , Canada , Alaska , and the northeastern tip of Siberia , and spend winters in warm parts of North America from southwestern British Columbia through parts of the United States to Mexico . In 1750 the English naturalist George Edwards included an illustration and a description of the snow goose in
1512-537: The Berkeley Mine shaft, the older mine gave its name to the pit. The open-pit style of mining superseded underground operations because it was far more economical and much less dangerous than underground mining. Within the first year of operation, the pit extracted 17,000 tons of ore per day at a grade of 0.75% copper. Ultimately, about 1,000,000,000 tons of material were mined from the Berkeley Pit. Copper
1575-580: The Hudson Bay coastline. The cause of this overpopulation may be the heavy conversion of land from forest and prairie to agricultural usage in the 20th century. Since the late 1990s, efforts have been underway in the U.S. and Canada to reduce the North American population of lesser snow and Ross's geese to sustainable levels due to the documented destruction of tundra habitat in Hudson Bay and other nesting areas. The Light Goose Conservation Order
1638-402: The areas surrounding open-pit mines. Open-pit gold mining is one of the highest potential mining threats on the environment as it affects the air and water chemistry. The exposed dust may be toxic or radioactive, making it a health concern for the workers and the surrounding communities. Open-pit nickel mining has led to environmental degradation and pollution in developing countries such as
1701-426: The common description as "snows" and "blues". White-morph birds are white except for black wing tips, but blue-morph geese have bluish-gray plumage replacing the white except on the head, neck and tail tip. The immature blue phase is drab or slate-gray with little to no white on the head, neck, or belly. Both snow and blue phases have rose-red feet and legs, and pink bills with black tomia ("cutting edges"), giving them
1764-401: The dead geese succumbed due to drinking the acidic metalliferous water. After this event, Atlantic Richfield (AR) and Montana Resources (MR) further enhanced the waterfowl protection efforts which had been in place since 1996. A new Waterfowl Protection Plan was developed and allowed for adaptive management, testing, and incorporation new tools and techniques. Deterrents such as Phoenix Wailers,
1827-446: The district in 1864. Placer deposits were mined out by 1867. Silver vein lodes were then the most productive until copper was discovered in 1881. Open-pit mining started in 1955. Copper has historically been the main metal produced, though lead , zinc , manganese , silver and gold have been produced at various times. Open pit Open-pit mines are used when deposits of commercially useful ore or rocks are found near
1890-682: The division. The smaller subspecies, the lesser snow goose ( C. c. caerulescens ), lives from central northern Canada to the Bering Straits area. The lesser snow goose stands 64 to 79 cm (25 to 31 in) tall and weighs 2.05 to 2.7 kg (4.5 to 6.0 lb). The larger subspecies, the greater snow goose ( C. c. atlanticus ), nests in northeastern Canada. It averages about 3.2 kg (7.1 lb) and 79 cm (31 in), but can weigh up to 4.5 kg (9.9 lb). The wingspan for both subspecies ranges from 135 to 165 cm (53 to 65 in). Long-term pair bonds are usually formed in
1953-601: The ducks and geese in the genus Anas . Linnaeus included a brief description, coined the binomial name Anas caerulescens and cited Edwards' work. The snow goose is now placed in the genus Anser that was introduced by the French zoologist Mathurin Jacques Brisson in 1760. The scientific name is from the Latin anser , "goose", and caerulescens , "bluish", derived from caeruleus , "dark blue". The snow goose
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2016-472: The environment. The dumps are usually fenced off to prevent livestock denuding them of vegetation. The open pit is then surrounded with a fence , to prevent access, and it generally eventually fills up with ground water . In arid areas it may not fill due to deep groundwater levels. In Germany, the world's largest producer of lignite (virtually all of which these days is mined open-pit), the former mines are usually converted to artificial lakes . To mitigate
2079-454: The harsh conditions of the water. Intense competition for the limited resources caused these species to evolve the production of highly toxic compounds to improve survivability. Natural products such as berkeleydione , berkeleytrione , and berkelic acid have been isolated from these organisms which show selective activity against cancer cell lines. Some of these species ingest metals and are being investigated as an alternative means of cleaning
2142-429: The hole. The interval of the benches depends on the deposit being mined, the mineral being mined, and the size of the machinery that is being used. Generally, large mine benches are 12 to 15 metres thick. In contrast, many quarries do not use benches, as they are usually shallow. Mining can be conducted on more than one bench at a time, and access to different benches is done with a system of ramps. The width of each bench
2205-539: The lesser snow goose exceeds 5 million birds, an increase of more than 300% since the mid-1970s. The population is increasing at a rate of more than five percent per year. Non-breeding geese (juveniles or adults that fail to nest successfully) are not included in this estimate, so the total number of geese is likely higher. Lesser snow goose population indices are the highest they have been since population records have been kept, and evidence suggests that large breeding populations are spreading to previously untouched sections of
2268-454: The mine by 10 to 15 years. One technique used in depressurization is annealing. Annealing is the slow heating and cooling of a metal, alloy or glass. This slow heating and cooling relieves the internal stress of surrounding areas. Annealing will increase a material's workability and durability, which overall increases open-pit mine safety. When groundwater pressures cause problems in open-pit mines, horizontal drains are used to aid in accelerating
2331-450: The mine floor due to excessive uplift pressure. A groundwater control system must be installed to fix problems caused by hydrology. The formation of an appropriate open-pit slope design, changes throughout the life of a mine. It is based mainly on an ever-increasing understanding of the rock mass conditions, including groundwater and associated pressures that may be acting within the slopes. The reduction of groundwater related to pore pressures
2394-491: The north shore of O'ahu . They were seen and photographed several times over the course of 3-4 months. In Central America , vagrants are frequently encountered during winter. Outside of the nesting season, they usually feed in flocks. In winter, snow geese feed on left-over grain in fields. They migrate in large flocks, often visiting traditional stopover habitats in spectacular numbers. Snow geese frequently travel and feed alongside greater white-fronted geese ; in contrast,
2457-514: The owls, since they are predatory, were capable of keeping competing predators away from the nests. A similar association as with the owls has been noted between geese and rough-legged hawks . Additional predators at the nest have reportedly included wolves , coyotes and all three North American bear species. Few predators regularly prey on snow geese outside of the nesting season, but bald eagles (as well as possibly golden eagles ) will readily attack wintering geese. The breeding population of
2520-582: The pit by researchers performing water quality testing. ARCO , the custodian of the pit, denied that the toxic water caused the death of the geese, attributing the deaths to an acute aspergillosis infection that may have been caused by a grain fungus, as substantiated by necropsy findings from Colorado State University . These findings were disputed by the State of Montana on the basis of its own lab tests. Necropsies showed their esophagi were lined with burns and sores from exposure to acidic metalliferous water. As
2583-412: The pit was closed, the water pumps in the nearby Kelley Mine, 3,800 ft (1,200 m) below the surface, were turned off, and groundwater began to slowly fill the Berkeley Pit, rising at about the rate of one foot (30 cm) per month. Since its closure, the water level in the pit has risen to within 150 feet (46 m) of the "protective water level", above which the polluted water might flow into
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2646-446: The presence of unextracted sulfide minerals , some forms of toxic minerals in the gangue , and often cyanide which is used to treat gold ore via the cyanide leach process . If proper environmental protections are not in place, this toxicity can harm the surrounding environment. Open-pit mining involves the process of disrupting the ground, which leads to the creation of air pollutants. The main source of air pollutants comes from
2709-407: The problem of acid mine drainage mentioned above, flooding is often done with the water of nearby rivers instead of using groundwater alone. In some cases, calcium oxide or other basic chemicals have to be added to the water to neutralize the pH -value. Gold is generally extracted in open-pit mines at 1 to 5 ppm (parts per million) but in certain cases, 0.75 ppm gold is economical. This
2772-474: The recommendation on ways to combat the growing population and the damage that the snow geese were creating in the arctic breeding grounds. The committee recommended relaxing hunting restrictions and giving hunters a better opportunity to harvest more snow geese on their way back to the breeding grounds in the spring. The suggested restrictions were to allow the use of electronic callers, unplugged shotguns, extended shooting hours, and no bag limits. Two years after
2835-404: The rocks are, and the type of rocks involved. It also depends on the amount of structural weaknesses occur within the rocks, such as a faults , shears , joints or foliations . The walls are stepped. The inclined section of the wall is known as the batter, and the flat part of the step is known as the bench or berm. The steps in the walls help prevent rock falls continuing down the entire face of
2898-471: The same habitat. Major nest predators include Arctic foxes and skuas . The biggest threat occurs during the first couple of weeks after the eggs are laid and then after hatching. The eggs and young chicks are vulnerable to these predators, but adults are generally safe. They have been seen nesting near snowy owl nests, which is likely a solution to predation. Their nesting success was much lower when snowy owls were absent, leading scientists to believe that
2961-471: The same species. The color phases are genetically controlled. The dark phase results from a single dominant gene and the white phase is homozygous recessive. When choosing a mate, young birds will most often select a mate that resembles their parents' coloring. If the birds were hatched into a mixed pair, they will mate with either color phase. The species is divided into two subspecies on the basis of size and geography. Size overlap has caused some to question
3024-407: The second year, although breeding does not usually start until the third year. Females are strongly philopatric, meaning they will return to the place they hatched to breed. Snow geese often nest in colonies. Nesting usually begins at the end of May or during the first few days of June, depending on snow conditions. The female selects a nest site and builds the nest on an area of high ground. The nest
3087-412: The slope depressurization process. Which helps to prevent large scale slope failure in the mine. Horizontal drains are used to lower pore pressure by reducing groundwater head, which enhances slope stability. A form of open-cast quarrying may be carried out as 'untopping'. This is done where a previous underground mine is becoming uneconomic or worked-out, but still leaves valuable rock in place, often as
3150-663: The southern end of Butte. Residents were compensated at market value for their acquired property. The Berkeley Pit is located within the Butte Mine Flooding Operable Unit, a part of the Silver Bow Creek/Butte Area Environmental Protection Agency Superfund site. The pit itself was added to the federal Superfund site list in 1987. The Berkeley Pit is a low spot and acts like a sump for contaminated water. For this reason, it
3213-558: The surface where the overburden is relatively thin. In contrast, deeper mineral deposits can be reached using underground mining. Open-pit mining is considered one of the most dangerous sectors in the industrial world . It causes significant effects to miners' health, as well as damage to the ecological land and water. Open-pit mining causes changes to vegetation, soil, and bedrock, which ultimately contributes to changes in surface hydrology, groundwater levels, and flow paths. Additionally, open-pit produces harmful pollutants depending on
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#17327805330103276-516: The third volume of his A Natural History of Uncommon Birds . He used the English name "The blue-winged goose". Edwards based his hand-coloured etching on a preserved specimen that had been brought to London from the Hudson Bay area of Canada by James Isham . When in 1758 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the tenth edition , he placed the snow goose with
3339-416: The transportation of minerals, but there are various other factors including drilling, blasting and the loading and unloading of overburden. These type of pollutants cause significant damage to public health and safety in addition to damaging the air quality. The inhalation of these pollutants can cause issues to the lungs and ultimately increase mortality. Furthermore, the pollutants affect flora and fauna in
3402-603: The tundra. The lesser snow goose travels through the Central Flyway , Mississippi Flyway , and Pacific Flyway across prairie and rich farmland to their wintering grounds on grassland and agricultural fields across the United States and Mexico, especially the Gulf coastal plain . The larger and less numerous greater snow goose travels through the Atlantic Flyway and winters on a relatively more restricted range on
3465-570: The two tend to avoid travelling and feeding alongside Canada geese , which are often heavier birds. The population of greater snow geese was in decline at the beginning of the 20th century, but has now recovered to sustainable levels. Snow geese in North America have increased to the point where the tundra breeding areas in the Arctic and the saltmarsh wintering grounds are both becoming severely degraded, and this affects other species using
3528-517: The type of mineral being mined, and the type of mining process being used. Miners typically drill a series of test holes to locate an underground ore body. From the extracted samples, they can determine the extent of the ore. This helps them determine the likely location of the veins or benches of ore and its commercial value. Open-pit mines that produce building materials and dimension stone are commonly referred to as quarries . Open-cast mines are dug on benches , which describe vertical levels of
3591-466: The wall. In some instances additional ground support is required and rock bolts , cable bolts and shotcrete are used. De-watering bores may be used to relieve water pressure by drilling horizontally into the wall, which is often enough to cause failures in the wall by itself. A haul road is usually situated at the side of the pit, forming a ramp up which trucks can drive, carrying ore and waste rock. Open-pit mines are typically worked until either
3654-697: The water. The mine is at an altitude of 4,698 feet (1432 m) above mean sea level. According to the Record of Decision, the pit water lever is not to exceed 5,410 feet above sea level. The Butte mining district is characterized by the Late Cretaceous boulder batholith which metamorphosed surrounding rocks during the Laramide orogeny . Ore formation occurred with the intrusion of the Butte quartz monzonite pluton . Mining of sulfide minerals began in
3717-403: The world. Listed are the world's ten largest open-pit mines in 2015. Snow geese The snow goose ( Anser caerulescens ) is a species of goose native to North America. Both white and dark morphs exist, the latter often known as blue goose . Its name derives from the typically white plumage . The species was previously placed in the genus Chen , but is now typically included in
3780-524: Was achieved by bulk heap leaching at the Peak Hill mine in western New South Wales , near Dubbo , Australia . Nickel , generally as laterite, is extracted via open-pit down to 0.2%. Copper can be extracted at grades as low as 0.11% to 0.2%. Open-pit mining is a common method to extract minerals and samples from the Earth. Due to being cost-effective, this method is very popular and is used all over
3843-492: Was also causing critical damage to other varieties of waterfowl species and other wildlife that uses the arctic and sub-arctic grounds for home habitat. The increase in population in substantial amounts raised concern to then DU chief biologist Dr. Bruce Batt who was part of a committee that put together various data and submitted it to the U.S. Fish and Wildlife Service and the Canadian Wildlife Service with
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#17327805330103906-441: Was established in 1997 and federally mandated in 1999. Increasing hunter bag limits, extending the length of hunting seasons, and adding new hunting methods have all been successfully implemented, but have not reduced the overall population of snow geese in North America. The late 1990s was when the mid-continent population of snow geese was recognized as causing significant damage to the arctic and sub-arctic breeding grounds which
3969-463: Was the principal metal produced, although other metals were also extracted, including silver and gold . Two communities and much of Butte's previously crowded east side were consumed by land purchases to expand the pit during the 1970s. The Anaconda Company bought the homes, businesses and schools of the working-class communities of Meaderville, East Butte, and McQueen, east of the pit site. Many of these homes were either destroyed, buried, or moved to
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