Summitville mine
Encyclopedia
The Summitville mine was a gold mining
site in Rio Grande County, Colorado
25 miles (40 km) south of Del Norte
. It is remembered for the environmental damage caused in the 1980s by the accidental leakage of mining by-products into local waterways and then the Alamosa River
.
was discovered at Summitville in 1870. By 1885 there were more than 250 individual claims in operation. The site was soon mined out, with the weather of the 3,500 m high site adding to difficulties. The site was re-opened on a number of occasions for gold or other metals but with little success, and prior to the site's acquisition in 1984 the last survey was in the early 1970s for copper
. The total amount of gold extracted from the site from 1873 until 1959 was around 257,600 troy ounces (8,012 kg).
In 1984 an area of 1230 acres (5 km²) was acquired by the Galactic Resources Ltd. subsidiary Summitville Consolidated Mining Company, Inc. (SCMCI). They began a new large-scale open pit operation covering 550 acres (2.2 km²). New techniques were used to extract gold from otherwise uneconomic ore
.
The mining involved the treatment of pyritic
ore with a sodium cyanide
solution to leach the gold out of the ore—heap leaching (see also cyanide process). The solution (leachate
) was then removed from the ore and the valuable metals extracted using activated carbon
. SCMCI leached around 10 million tons of ore on a 73 acre (0.29542078 km²) heap leach pad. The mining operations were finished in October 1991 with the leaching continuing until March 1992. A total of 294,365 troy ounces (9,155.8 kg) of gold and 319,814 troy ounces (9,947.3 kg) of silver were recovered. SCMCI then closed the site and converted on-site equipment for the detoxification process, with around 160 million U.S. gallons (610,000 m³) of stored water needing treatment.
order by the state government, concerned with metal levels in nearby water due to the run-off of excess water from the heap leach pad and through the damaged pad liner. Possibly 85,000 US gallons (320 m³) of contaminated water had leaked into nearby creeks. In December 1992 Galactic Resources Ltd. declared itself bankrupt and declared that the site clean-up operations would halt immediately. The site clean-up was undertaken by the United States Environmental Protection Agency (EPA), from 1994 under Superfund Emergency Response. The main problem was the contaminated water held in an inadequate pond system. Another source of contamination was water leaking from older underground workings. The EPA estimated that 3,000 US gallons (11 m³) were leaking from the site every minute. However, despite the water having a pH
of around 3 (acid
ic), a USGS study stated that the run-off was no serious threat.
$155 million was spent on the site for detoxification and to reduce leakage. Robert Friedland
, the chairman of Galactic Resources Ltd. paid around $30 million in settlement. Heavy metals
and acid
from the mine are suspected to have killed stocked fish in downstream reservoirs on the Alamosa River
in 1990. Although cyanide from the heap leach pads also leaked in the watershed, cyanide is believed to have quickly volatilized into the atmosphere without damaging downstream aquatic life.
Water runoff from the Summitville mine flows down Wrightman Fork, mixes with naturally acidic runoff from unmined areas, flows into the Alamosa River
and flows out of the mountains into the San Luis Valley
, where it is used for crop irrigation. A United States Geological Survey
investigation arrived at three major conclusions:
Gold mining
Gold mining is the removal of gold from the ground. There are several techniques and processes by which gold may be extracted from the earth.-History:...
site in Rio Grande County, Colorado
Rio Grande County, Colorado
Rio Grande County is one of the 64 counties of the State of Colorado of the United States. The county is named for the Rio Grande , which flows through the county. The county population was 12,413 at U.S. Census 2000...
25 miles (40 km) south of Del Norte
Del Norte, Colorado
The Town of Del Norte is a Statutory Town in and the county seat of Rio Grande County, Colorado, United States. The town population was 1,705 at the 2000 census.-Geography:Del Norte is located at ....
. It is remembered for the environmental damage caused in the 1980s by the accidental leakage of mining by-products into local waterways and then the Alamosa River
Alamosa River
The Alamosa River is a river in the southern part of the U.S. state of Colorado. It is about long, flowing roughly east through the San Luis Valley. Its watershed comprises about .The river's name means "shaded with cottonwoods" in Spanish....
.
History
GoldGold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
was discovered at Summitville in 1870. By 1885 there were more than 250 individual claims in operation. The site was soon mined out, with the weather of the 3,500 m high site adding to difficulties. The site was re-opened on a number of occasions for gold or other metals but with little success, and prior to the site's acquisition in 1984 the last survey was in the early 1970s for copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
. The total amount of gold extracted from the site from 1873 until 1959 was around 257,600 troy ounces (8,012 kg).
In 1984 an area of 1230 acres (5 km²) was acquired by the Galactic Resources Ltd. subsidiary Summitville Consolidated Mining Company, Inc. (SCMCI). They began a new large-scale open pit operation covering 550 acres (2.2 km²). New techniques were used to extract gold from otherwise uneconomic ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
.
The mining involved the treatment of pyritic
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
ore with a sodium cyanide
Sodium cyanide
Sodium cyanide is an inorganic compound with the formula NaCN. This highly toxic colorless salt is used mainly in gold mining but has other niche applications...
solution to leach the gold out of the ore—heap leaching (see also cyanide process). The solution (leachate
Leachate
Leachate is any liquid that, in passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed....
) was then removed from the ore and the valuable metals extracted using activated carbon
Activated carbon
Activated carbon, also called activated charcoal, activated coal or carbo activatus, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions.The word activated in the name is sometimes replaced...
. SCMCI leached around 10 million tons of ore on a 73 acre (0.29542078 km²) heap leach pad. The mining operations were finished in October 1991 with the leaching continuing until March 1992. A total of 294,365 troy ounces (9,155.8 kg) of gold and 319,814 troy ounces (9,947.3 kg) of silver were recovered. SCMCI then closed the site and converted on-site equipment for the detoxification process, with around 160 million U.S. gallons (610,000 m³) of stored water needing treatment.
The cease and desist order and aftermath
In 1991 SCMCI was served with a cease and desistCease and desist
A cease and desist is an order or request to halt an activity and not to take it up again later or else face legal action. The recipient of the cease-and-desist may be an individual or an organization....
order by the state government, concerned with metal levels in nearby water due to the run-off of excess water from the heap leach pad and through the damaged pad liner. Possibly 85,000 US gallons (320 m³) of contaminated water had leaked into nearby creeks. In December 1992 Galactic Resources Ltd. declared itself bankrupt and declared that the site clean-up operations would halt immediately. The site clean-up was undertaken by the United States Environmental Protection Agency (EPA), from 1994 under Superfund Emergency Response. The main problem was the contaminated water held in an inadequate pond system. Another source of contamination was water leaking from older underground workings. The EPA estimated that 3,000 US gallons (11 m³) were leaking from the site every minute. However, despite the water having a pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
of around 3 (acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ic), a USGS study stated that the run-off was no serious threat.
$155 million was spent on the site for detoxification and to reduce leakage. Robert Friedland
Robert Friedland
Robert Martin Friedland is an international financier and businessman. Since the early 1980s, he has specialized in securing funding for the exploration and development of mineral and energy resources and advanced technology ventures...
, the chairman of Galactic Resources Ltd. paid around $30 million in settlement. Heavy metals
Heavy metals
A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight,...
and acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
from the mine are suspected to have killed stocked fish in downstream reservoirs on the Alamosa River
Alamosa River
The Alamosa River is a river in the southern part of the U.S. state of Colorado. It is about long, flowing roughly east through the San Luis Valley. Its watershed comprises about .The river's name means "shaded with cottonwoods" in Spanish....
in 1990. Although cyanide from the heap leach pads also leaked in the watershed, cyanide is believed to have quickly volatilized into the atmosphere without damaging downstream aquatic life.
Natural versus manmade pollution
Rocks in the Summitville area were millions of years ago subjected to acid-sulfate alteration, which causes the streams that drain the area to be naturally acidic and naturally high in metals. The very names of nearby creeks are evidence of poor natural water quality: Iron Creek, Alum Creek, and Bitter Creek. Mining at Summitville, by exposing more rock surface to weathering, increased acidity and concentrations of dissolved metals in runoff from the mine area. The degradation in Summitville runoff water quality has its origin in both decades-old mining structures, such as the Reynold’s adit, and the open-pit mining of 1985-1992.Water runoff from the Summitville mine flows down Wrightman Fork, mixes with naturally acidic runoff from unmined areas, flows into the Alamosa River
Alamosa River
The Alamosa River is a river in the southern part of the U.S. state of Colorado. It is about long, flowing roughly east through the San Luis Valley. Its watershed comprises about .The river's name means "shaded with cottonwoods" in Spanish....
and flows out of the mountains into the San Luis Valley
San Luis Valley
The San Luis Valley is an extensive alpine valley in the U.S. states of Colorado and New Mexico covering approximately and sitting at an average elevation of above sea level. The valley sits atop the Rio Grande Rift and is drained to the south by the Rio Grande River, which rises in the San Juan...
, where it is used for crop irrigation. A United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
investigation arrived at three major conclusions:
- ”Extreme acid-rock drainage is the dominant long-term environmental concern at the Summitville mine and could have been predicted given the geological characteristics of the deposit. Extensive remedial efforts are required to isolate both unweathered sulfides and soluble metal salts in the open-pit area and mine-waste piles from weathering and dissolution.”
- ”It is likely that natural contamination adversely affected water quality and fish habitat in the Alamosa River long before and will continue to have adverse affects even when acid drainage from Summitville is remediated. Thus, reasonable natural conditions for the Alamosa River must be established in order to set realistic remediation conditions for the Summitville site.”
- ”Results of studies as of late 1993 indicate that mining at Summitville has had no discernable short-term adverse effects on barley or alfalfa crops irrigated with Alamosa River water. Remediation of the site will help to ensure that no adverse effects occur over the longer term.”