Leviathan Mine
Encyclopedia
Leviathan Mine is a United States superfund
site (CERCLIS ID: CAD98067685) at an abandoned open-pit
sulfur
mine
located in Alpine County, California
. The mine is located at on the eastern slope of the Sierra Nevada at about 7000 feet (2,133.6 m) elevation, 6 miles (9.7 km) east of Markleeville and 24 miles (38.6 km) southeast of Lake Tahoe
. The mine site comprises approximately 250 acres (101.2 ha) of land surrounded by the Toiyabe National Forest, which is only accessible a few months a year. The approximately 22 million tons of sulfur ore-containing crushed rock at the mine are responsible for contaminating the Leviathan and Aspen Creek, which join with Mountaineer Creek to form Bryant Creek which ultimately empties into the East Fork of the Carson River
. These water bodies are listed as 303(d) impaired . The site location is seismically active .
miners. Over between 1863 and 1870, 500 tons of copper sulfate was removed from two adit
s. This copper sulfate was used for silver
ore
refining. A large sulfur deposit was discovered in in one of the adits and the mine was subsequently abandoned . Between 1935 and 1941 Calpine Corporation of Los Angeles
, which subleased the mine from the Texas Gulf Sulfur Company, conducted subsurface sulfur mining and recovered 5,000 tons of sulfur. Mining was suspended in 1941 due to the hazardous nature of mining sulfur underground . In 1945 the Siskon Mining Corporation, acquired the mine .
Open-pit mining
of sulfur was initiated at the site when Anaconda Copper Mining Company purchased the Leviathan in 1951. The extracted sulfur was used for copper
ore processing at Anaconda Copper Mine (Nevada)
. During its excavating operations and Leviathan (1953–1962), Anaconda turned the original mine into a 50 acres (20.2 ha), 400 feet (121.9 m) pit, and removed approximately 500,000 long ton
s of sulfur . During this time period acid mine drainage
(AMD) began contaminating Leviathan Creek. In 1963, Anaconda sold the property to founders of the Alpine Mining Enterprises, Zella N. Mann and William Chris Mann, who was the Alpine County Clerk .
acquired Leviathan from Alpine Mining Enterprises in 1984, and the California State Water Resources Control Board
gained jurisdiction the over the property. The Leviathan Mine Pollution Abatement Project consisted of building drains beneath the pit to capture contaminated water and making evaporation pond
s, filling and regrading
the pit, and separating uncontaminated surface water
from AMD groundwater
. Results of the project include the discovery of unknown acid
ic springs
and accidental AMD discharge directly in to Leviathan creek via a drain line .
In 1997 the United States Environmental Protection Agency
(EPA) became involved in the clean up of Leviathan Mine at the request of the Washoe Tribe of Nevada and California
. The tribe had concerns about overflow from evaporation ponds onto downstream tribal lands and the impacts of AMD on their cultural and natural resource
s . The EPA Region IX tried unsuccessfully to use a lime neutralization treatment of the AMD . In 1998, the Atlantic Richfield Company (ARCO
), whom purchased Anaconda in 1977, was issued an Administrative Order on Consent (AOC) by the EPA that obligated them to aid in the mitigation of AMD flow in to Leviathan creek. . However, due to the use of unproven technologies implemented by ARCO Environmental Remediation, L.L.C. and the logistical challenges of getting supplies to the mine this effort had limited success . Then in 1999, a biphasic neutralization water treatment plant was established by the LRWQCB to treat AMD in the evaporation ponds and minimize over flow into Leviathan Creek .
In 1999 the EPA proposed making Leviathan's open-pit sulfur mine a superfund site by adding it to the National Priorities List
for hazardous waste sites . In 2000 EPA added the mine to the NPL , and had the written support of the Washoe Tribe, Alpine County, California
, the State of Nevada
, Douglas County, Nevada
and the Carson River Conservancy District . The LRWQCB was issued an Administrative Abatement Action (AAA) in 2000 (which was renewed in 2001, 2002, 2003, 2004, and 2005) by the EPA in order to continue the biphasic treatment, water quality monitoring and other actives . Since 2005, the involvement of the LRWQCB is determined by the EPA Remedial Project Manager for the mine . In 2000, a unilateral administrative order was issued to ARCO, in which, the EPA required ARCO to conduct early response actions and develop a long-term response plan for mitigating AMD.
In 1993 the State of California set up a pilot scale one-cell bioreactor
with manure
substrate for AMD treatment at Leviathan Creek Seep. By 1998, researchers from the University of Nevada-Reno (UNR) installed a two cell bioreactor at Aspen seep. By 2001, the Aspen seep bioreactor treated 2.5 million gallons of ARD. The design evolved over time and in 2003, at the behest of the State of California, ARCO and the UNR researchers developed a compost
-free sulfate
reducing bioreactor at Aspen Seep .
is produced at the open-pit mine when water, such as rain
, snow
melt or groundwater
, interacts with the waste rock. This sulfuric acid leaches
contaminants from surrounding rock, such as arsenic
, copper
, nickel
, zinc
, chromium
, aluminum and iron
. This acid rock drainage ARD, with a low pH, and high concentrations of dissolved sulfate and metal
s, flows into the surrounding watershed
and has adverse affects on water quality through deposition of metal-rich precipitates, which cascade through the ecosystem
affecting algae
, insect
, and fish
. The site is unvegetated
and is susceptible to erosion
due to several long steep slopes. The instability resulting form the open-pit mine has resulted in several landslide
s, with one affecting over 100 acres (40.5 ha) .
ous and non-cancerous health effects depending on where, when, and how long the exposure occurred. Arsenic
poses the most significant health risk to exposed individuals via contact with contaminated surface water
and sediment
. Other risks for exposure include eating fish, plants and wild game collected near the mine, inhalation of dust
near the mine, and or eating animals raised near Leviathan. In general, avoiding contact with mine tailings, surface water, and sediments in Leviathan, Aspen, and Bryant creeks, as well as the River Ranch Irrigation channel will reduce contaminate exposure and therefore reduce health risks. .
of the outflow to the point that iron
precipitates
out of solution as ferric hydroxide and arsenic co-precipitates with the ferric hydroxide. This sludge
is then removed and disposed of at an appropriate hazardous waste
facility. In Phase II the pH of the effluent is raised again and additional metals precipitate. Much of this sludge is non-hazardous and is stored at Leviathan. The remaining wastewater
can then be discharged into Leviathan Creek .
employs sulfate-reducing microbes (e.g. Desulfovibrio
sp.) to reduce sulfate
to sulfide
at pH 4.0
. However, the ARD at Aspen Seep is too acidic (pH 3.1) and is pretreated with sodium hydroxide solution. Ethanol
, the carbon
source for the sulfate reducing microbes, is also added to the system . The solution is reduced from sulfate to sulfide in Bioreactor No. 1, which is lined with 60-millimeter high-density polyethylene (HDPE) and filled with river rocks, which aid in the flow of effluent
. The sulfide effluent is passed into Bioreactor No. 2 for additional metal removal. Next, sodium hydroxide is added to the effluent to increase the pH to neutral, and it is sent through two settling ponds (to allow for the settling of metal sulfide precipitates) and a rock-lined aeration
channel for degassing of hydrogen sulfide
. At the end of the aeration channel the effluent is released into Aspen Creek .
Superfund
Superfund is the common name for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 , a United States federal law designed to clean up sites contaminated with hazardous substances...
site (CERCLIS ID: CAD98067685) at an abandoned open-pit
Open-pit mining
Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow....
sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
mine
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
located in Alpine County, California
Alpine County, California
Alpine County is the smallest county, by population, in the U.S. state of California. As of 2010, it had a population of 1,175, all rural. There are no incorporated cities in the county. The county seat is Markleeville...
. The mine is located at on the eastern slope of the Sierra Nevada at about 7000 feet (2,133.6 m) elevation, 6 miles (9.7 km) east of Markleeville and 24 miles (38.6 km) southeast of Lake Tahoe
Lake Tahoe
Lake Tahoe is a large freshwater lake in the Sierra Nevada of the United States. At a surface elevation of , it is located along the border between California and Nevada, west of Carson City. Lake Tahoe is the largest alpine lake in North America. Its depth is , making it the USA's second-deepest...
. The mine site comprises approximately 250 acres (101.2 ha) of land surrounded by the Toiyabe National Forest, which is only accessible a few months a year. The approximately 22 million tons of sulfur ore-containing crushed rock at the mine are responsible for contaminating the Leviathan and Aspen Creek, which join with Mountaineer Creek to form Bryant Creek which ultimately empties into the East Fork of the Carson River
Carson River
The Carson River is a northwestern Nevada river that empties into the Carson Sink, an endorheic basin. The main stem of the river is long....
. These water bodies are listed as 303(d) impaired . The site location is seismically active .
Mining history
Pre-open pit mining began in 1863 by Comstock LodeComstock Lode
The Comstock Lode was the first major U.S. discovery of silver ore, located under what is now Virginia City, Nevada, on the eastern slope of Mount Davidson, a peak in the Virginia Range. After the discovery was made public in 1859, prospectors rushed to the area and scrambled to stake their claims...
miners. Over between 1863 and 1870, 500 tons of copper sulfate was removed from two adit
Adit
An adit is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, and ventilated.-Construction:...
s. This copper sulfate was used for silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
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....
refining. A large sulfur deposit was discovered in in one of the adits and the mine was subsequently abandoned . Between 1935 and 1941 Calpine Corporation of Los Angeles
Los Ángeles
Los Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...
, which subleased the mine from the Texas Gulf Sulfur Company, conducted subsurface sulfur mining and recovered 5,000 tons of sulfur. Mining was suspended in 1941 due to the hazardous nature of mining sulfur underground . In 1945 the Siskon Mining Corporation, acquired the mine .
Open-pit mining
Open-pit mining
Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow....
of sulfur was initiated at the site when Anaconda Copper Mining Company purchased the Leviathan in 1951. The extracted sulfur was used 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...
ore processing at Anaconda Copper Mine (Nevada)
Anaconda Copper Mine (Nevada)
The Anaconda Copper Mine is an open pit copper mine in Lyon County, Nevada that was owned and operated by the Anaconda Mining Company. It is located adjacent to the town of Yerington. The company town of Weed Heights was built to support the mining operation which ran until 1978.-History:The...
. During its excavating operations and Leviathan (1953–1962), Anaconda turned the original mine into a 50 acres (20.2 ha), 400 feet (121.9 m) pit, and removed approximately 500,000 long ton
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...
s of sulfur . During this time period acid mine drainage
Acid mine drainage
Acid mine drainage , or acid rock drainage , refers to the outflow of acidic water from metal mines or coal mines. However, other areas where the earth has been disturbed may also contribute acid rock drainage to the environment...
(AMD) began contaminating Leviathan Creek. In 1963, Anaconda sold the property to founders of the Alpine Mining Enterprises, Zella N. Mann and William Chris Mann, who was the Alpine County Clerk .
Post-mining clean-up
Site clean up began with the 1983-1985 formation of the Leviathan Mine Pollution Abatement Project by the Lahontan Regional Water Quality Control Board (LRWQCB) which was built in an effort to mitigate acid mine drainage . The State of CaliforniaCalifornia
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
acquired Leviathan from Alpine Mining Enterprises in 1984, and the California State Water Resources Control Board
California State Water Resources Control Board
The California State Water Resources Control Board is one of five branches of the California Environmental Protection Agency.-History:...
gained jurisdiction the over the property. The Leviathan Mine Pollution Abatement Project consisted of building drains beneath the pit to capture contaminated water and making evaporation pond
Evaporation pond
Evaporation ponds are artificial ponds with very large surface areas that are designed to efficiently evaporate water by sunlight and exposure to the ambient temperatures.- Uses :...
s, filling and regrading
Land grading
Grading in civil engineering and construction is the work of ensuring a level base, or one with a specified slope, for a construction work such as a foundation, the base course for a road or a railway, or landscape and garden improvements, or surface drainage...
the pit, and separating uncontaminated surface water
Surface water
Surface water is water collecting on the ground or in a stream, river, lake, wetland, or ocean; it is related to water collecting as groundwater or atmospheric water....
from AMD groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
. Results of the project include the discovery of unknown 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 springs
Spring (hydrosphere)
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...
and accidental AMD discharge directly in to Leviathan creek via a drain line .
In 1997 the United States Environmental Protection Agency
United States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
(EPA) became involved in the clean up of Leviathan Mine at the request of the Washoe Tribe of Nevada and California
Washoe Tribe of Nevada and California
The Washoe Tribe of Nevada and California are a federally recognized tribe of Washoe Indians, living in California and Nevada. They are several communities south and east of Lake Tahoe united under a tribal council...
. The tribe had concerns about overflow from evaporation ponds onto downstream tribal lands and the impacts of AMD on their cultural and natural resource
Natural resource
Natural resources occur naturally within environments that exist relatively undisturbed by mankind, in a natural form. A natural resource is often characterized by amounts of biodiversity and geodiversity existent in various ecosystems....
s . The EPA Region IX tried unsuccessfully to use a lime neutralization treatment of the AMD . In 1998, the Atlantic Richfield Company (ARCO
ARCO
Atlantic Richfield Company is an oil company with operations in the United States as well as in Indonesia, the North Sea, and the South China Sea. It has more than 1,300 gas stations in the western part of the United States. ARCO was originally formed by the merger of East Coast-based Atlantic...
), whom purchased Anaconda in 1977, was issued an Administrative Order on Consent (AOC) by the EPA that obligated them to aid in the mitigation of AMD flow in to Leviathan creek. . However, due to the use of unproven technologies implemented by ARCO Environmental Remediation, L.L.C. and the logistical challenges of getting supplies to the mine this effort had limited success . Then in 1999, a biphasic neutralization water treatment plant was established by the LRWQCB to treat AMD in the evaporation ponds and minimize over flow into Leviathan Creek .
In 1999 the EPA proposed making Leviathan's open-pit sulfur mine a superfund site by adding it to the National Priorities List
National Priorities List
The National Priorities List is the list of hazardous waste sites in the United States eligible for long-term remedial action financed under the federal Superfund program. Environmental Protection Agency regulations outline a formal process for assessing hazardous waste sites and placing them on...
for hazardous waste sites . In 2000 EPA added the mine to the NPL , and had the written support of the Washoe Tribe, Alpine County, California
Alpine County, California
Alpine County is the smallest county, by population, in the U.S. state of California. As of 2010, it had a population of 1,175, all rural. There are no incorporated cities in the county. The county seat is Markleeville...
, the State of Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, Douglas County, Nevada
Douglas County, Nevada
Douglas County is a county located in the northwestern part of the U.S. state of Nevada. As of 2000, the population was 41,259. As of 2010, the population was estimated to be 46,997.- History :...
and the Carson River Conservancy District . The LRWQCB was issued an Administrative Abatement Action (AAA) in 2000 (which was renewed in 2001, 2002, 2003, 2004, and 2005) by the EPA in order to continue the biphasic treatment, water quality monitoring and other actives . Since 2005, the involvement of the LRWQCB is determined by the EPA Remedial Project Manager for the mine . In 2000, a unilateral administrative order was issued to ARCO, in which, the EPA required ARCO to conduct early response actions and develop a long-term response plan for mitigating AMD.
In 1993 the State of California set up a pilot scale one-cell bioreactor
Bioreactor
A bioreactor may refer to any manufactured or engineered device or system that supports a biologically active environment. In one case, a bioreactor is a vessel in which a chemical process is carried out which involves organisms or biochemically active substances derived from such organisms. This...
with manure
Manure
Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...
substrate for AMD treatment at Leviathan Creek Seep. By 1998, researchers from the University of Nevada-Reno (UNR) installed a two cell bioreactor at Aspen seep. By 2001, the Aspen seep bioreactor treated 2.5 million gallons of ARD. The design evolved over time and in 2003, at the behest of the State of California, ARCO and the UNR researchers developed a compost
Compost
Compost is organic matter that has been decomposed and recycled as a fertilizer and soil amendment. Compost is a key ingredient in organic farming. At its most essential, the process of composting requires simply piling up waste outdoors and waiting for the materials to break down from anywhere...
-free sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
reducing bioreactor at Aspen Seep .
Environmental damage
Sulfuric acidSulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
is produced at the open-pit mine when water, such as rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
, snow
Snow
Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...
melt or groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
, interacts with the waste rock. This sulfuric acid leaches
Leaching
In general, leaching is the extraction of certain materials from a carrier into a liquid . Specifically, it may refer to:...
contaminants from surrounding rock, such as arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
, 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...
, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
, zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
, aluminum and iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
. This acid rock drainage ARD, with a low pH, and high concentrations of dissolved sulfate and metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
s, flows into the surrounding watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
and has adverse affects on water quality through deposition of metal-rich precipitates, which cascade through the ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
affecting algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
, and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. The site is unvegetated
Vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...
and is susceptible to erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
due to several long steep slopes. The instability resulting form the open-pit mine has resulted in several landslide
Landslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
s, with one affecting over 100 acres (40.5 ha) .
Human health concerns
Contact with contaminates from the mine can result in both cancerCancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
ous and non-cancerous health effects depending on where, when, and how long the exposure occurred. Arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
poses the most significant health risk to exposed individuals via contact with contaminated surface water
Surface water
Surface water is water collecting on the ground or in a stream, river, lake, wetland, or ocean; it is related to water collecting as groundwater or atmospheric water....
and sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
. Other risks for exposure include eating fish, plants and wild game collected near the mine, inhalation of dust
Dust
Dust consists of particles in the atmosphere that arise from various sources such as soil dust lifted up by wind , volcanic eruptions, and pollution...
near the mine, and or eating animals raised near Leviathan. In general, avoiding contact with mine tailings, surface water, and sediments in Leviathan, Aspen, and Bryant creeks, as well as the River Ranch Irrigation channel will reduce contaminate exposure and therefore reduce health risks. .
Biphasic neutralization water treatment
Biphasic neutralization water treatment is a two-step process. Phase I raises the pHPH
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 the outflow to the point that iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
precipitates
Precipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
out of solution as ferric hydroxide and arsenic co-precipitates with the ferric hydroxide. This sludge
Sludge
Sludge refers to the residual, semi-solid material left from industrial wastewater, or sewage treatment processes. It can also refer to the settled suspension obtained from conventional drinking water treatment, and numerous other industrial processes...
is then removed and disposed of at an appropriate hazardous waste
Hazardous waste
A hazardous waste is waste that poses substantial or potential threats to public health or the environment. According to the U.S. environmental laws hazardous wastes fall into two major categories: characteristic wastes and listed wastes.Characteristic hazardous wastes are materials that are known...
facility. In Phase II the pH of the effluent is raised again and additional metals precipitate. Much of this sludge is non-hazardous and is stored at Leviathan. The remaining wastewater
Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...
can then be discharged into Leviathan Creek .
Compost-free sulfate reducing bioreactor
The compost-free sulfate reducing bioreactorBioreactor
A bioreactor may refer to any manufactured or engineered device or system that supports a biologically active environment. In one case, a bioreactor is a vessel in which a chemical process is carried out which involves organisms or biochemically active substances derived from such organisms. This...
employs sulfate-reducing microbes (e.g. Desulfovibrio
Desulfovibrio
Desulfovibrio is a genus of Gram negative sulfate-reducing bacteria. Some species of Desulfovibrio are capable of transduction. Desulfovibrio species are commonly found in aquatic environments with high levels of organic material, as well as in water-logged soils, and form major community members...
sp.) to reduce sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
to sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
at pH 4.0
. However, the ARD at Aspen Seep is too acidic (pH 3.1) and is pretreated with sodium hydroxide solution. Ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
, the carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
source for the sulfate reducing microbes, is also added to the system . The solution is reduced from sulfate to sulfide in Bioreactor No. 1, which is lined with 60-millimeter high-density polyethylene (HDPE) and filled with river rocks, which aid in the flow of effluent
Effluent
Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent is defined by the United States Environmental Protection Agency as “wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers...
. The sulfide effluent is passed into Bioreactor No. 2 for additional metal removal. Next, sodium hydroxide is added to the effluent to increase the pH to neutral, and it is sent through two settling ponds (to allow for the settling of metal sulfide precipitates) and a rock-lined aeration
Aeration
Aeration is the process by which air is circulated through, mixed with or dissolved in a liquid or substance.-Aeration of liquids:-Methods:Aeration of liquids is achieved by:...
channel for degassing of hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
. At the end of the aeration channel the effluent is released into Aspen Creek .