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94-818: Mining in the Leadville area began in 1859 when prospectors working in the channels of the Arkansas River tributaries discovered gold at the mouth of California Gulch. In April 1860, one of the richest discoveries of placer gold in Colorado was discovered at California Gulch. By 1872, placer mining in California Gulch yielded more than $ 2,500,000, roughly equivalent to $ 47,674,478 today. In 1876, piles of sand once considered bothersome to placer gold miners, were discovered to contain lead carbonates and were traced back to California Gulch. This discovery propelled

188-516: A Superfund to remediate abandoned sites, or to litigate to force corporations to remediate their contaminated sites. Other countries have other mechanisms and commonly sites are rezoned to "higher" uses such as high density housing, to give the land a higher value so that after deducting cleanup costs there is still an incentive for a developer to purchase the land, clean it up, redevelop it and sell it on, often as apartments (home units). There are several tools for mapping these sites and which allow

282-458: A jail sentence for the polluter. Penalties must be significant as otherwise fines are treated as a normal expense of doing business. Compliance must be cheaper than to have continuous breaches. Assessment should be made of the risks of operations, transporting contaminated material, disposal of waste which may be contaminated including workers' clothes, and a formal emergency response plan should be developed. Every worker and visitor entering

376-450: A chemical free technology. Air microbubbles generated in water without adding any surfactant could be used to clean oil contaminated sediments. This technology holds promise over the use of chemicals (mainly surfactant) for traditional washing of oil contaminated sediments. In preparation for any significant remediation there should be extensive community consultation. The proponent should both present information to and seek information from

470-571: A concentration of 93% and bioaccumulation factor of 5.6, lead , mercury , zinc with a bioaccumulation factor of 3.6, and arsenic at a concentration of 22%. Black soldier fly larvae (BSFL) have also been used to monitor the degradation and reduction of anthropogenic oil contamination in the environment. Entomoremediation is considered viable as an accessible low-energy, low-carbon, and highly renewable method for environmental decontamination. Cleaning of oil contaminated sediments with self collapsing air microbubbles have been recently explored as

564-414: A faster rate than would larger particles. Most field applications of nanoremediation have used nano zero-valent iron (nZVI), which may be emulsified or mixed with another metal to enhance dispersion. That nanoparticles are highly reactive can mean that they rapidly clump together or react with soil particles or other material in the environment, limiting their dispersal to target contaminants. Some of

658-417: A remediation project. The use of incremental health risk is based on carcinogenic and other (e.g., mutagenic , teratogenic ) effects and often involves value judgements about the acceptable projected rate of increase in cancer . In some jurisdictions this is 1 in 1,000,000 but in other jurisdictions the acceptable projected rate of increase is 1 in 100,000. A relatively small incremental health risk from

752-483: A result, current blood-lead testing, outreach and education programs are being implemented in the Lake County area. The next step in the cleanup process is to conduct a 5-year review to determine the success of the current plan in protecting human health and the environment. The population in Leadville has been relatively stable for the last 30 years. Since 1983, several residential areas were able to be removed from

846-486: A rush of miners to the area. The town of Leadville was founded a year later by mine owners Horace Austin Warner Tabor and August Meyer . Mining, mineral processing, and smelting in and near Leadville produced gold, silver, lead, copper, manganese, and zinc for more than 130 years. Wastes generated during the mining and ore processing contained metals, such as cadmium, copper, lead, and zinc. These wastes remained on

940-459: A single project is not of much comfort if the area already has a relatively high health risk from other operations like incinerators or other emissions, or if other projects exist at the same time causing a greater cumulative risk or an unacceptably high total risk. An analogy often used by remediators is to compare the risk of the remediation on nearby residents to the risks of death through car accidents or tobacco smoking . Standards are set for

1034-634: A value of over $ 300 million at 2010 prices. Secondary ore minerals from the Sherman mine are popular with mineral collectors.The prominent ruins of the historic buildings and structures of the Hilltop Mine (above the more recent Sherman mine workings) are often visited and photographed by hikers and mountaineers. After 100 years as a major US mining district, the last active mine, the Black Cloud mine, owned by ASARCO , closed in 1999. While there

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1128-477: A walk-through replica of an underground hardrock mine, the Gold Rush room, with many specimens of native gold , a large collection of mineral specimes , and a mining art gallery. The Matchless mine and cabin, former home of Baby Doe Tabor , is open as a tourist attraction during the summer. Environmental remediation Environmental remediation is the cleanup of hazardous substances dealing with

1222-476: Is a controversial step as: Often corporations which do voluntary testing of their sites are protected from the reports to environmental agencies becoming public under Freedom of Information Acts , however a "Freedom of Information" inquiry will often produce other documents that are not protected or will produce references to the reports. In the US there has been a mechanism for taxing polluting industries to form

1316-414: Is a technology for soil remediation. During the process a desorber volatilizes the contaminants (e.g. oil, mercury or hydrocarbon) to separate them from especially soil or sludge. After that the contaminants can either be collected or destroyed in an offgas treatment system. Excavation processes can be as simple as hauling the contaminated soil to a regulated landfill , but can also involve aerating

1410-583: Is a variant of bioremediation in which insects decontaminate soils. Entomoremediation techniques engage microorganisms , collembolans , ants , flies , beetles , and termites . It is dependent on saprophytic insect larvae, resistant to adverse environmental conditions and able to bioaccumulate toxic heavy metal contaminants. Hermetia illucens (black soldier fly - BSF) is an important entomoremediation participant. H. illucens has been observed to reduce polluted substrate dry weight by 49%. H. illucens larvae have been observed to accumulate cadmium at

1504-449: Is also successful when utilized as the initial step in a multi-faceted remedial approach utilizing SEAR then In situ Oxidation, bioremediation enhancement or soil vapor extraction (SVE). Pump and treat involves pumping out contaminated groundwater with the use of a submersible or vacuum pump , and allowing the extracted groundwater to be purified by slowly proceeding through a series of vessels that contain materials designed to adsorb

1598-515: Is an effective remediation technology for soil. "Multi Phase Extraction" (MPE) is also an effective remediation technology when soil and groundwater are to be remediated coincidentally. SVE and MPE utilize different technologies to treat the off-gas volatile organic compounds (VOCs) generated after vacuum removal of air and vapors (and VOCs) from the subsurface and include granular activated carbon (most commonly used historically), thermal and/or catalytic oxidation and vapor condensation. Generally, carbon

1692-448: Is considered to be Not Under Control. Operable Unit 12, responsible for Sitewide Surface and Groundwater Quality, is currently in the remedial action phase of cleanup. This phase includes construction or implementation of the project design, but not complete cleanup. In order for the human exposure status of the site to be considered under control, contamination levels must be safe and controls must be in place to prevent human exposure. Since

1786-638: Is done by removal the waste materials are simply transported off-site for disposal at another location. The waste material can also be contained by physical barriers like slurry walls . The use of slurry walls is well-established in the construction industry. The application of (low) pressure grouting , used to mitigate soil liquefaction risks in San Francisco and other earthquake zones, has achieved mixed results in field tests to create barriers, and site-specific results depend upon many variable conditions that can greatly impact outcomes. Remedial action

1880-641: Is generally subject to an array of regulatory requirements, and may also be based on assessments of human health and ecological risks where no legislative standards exist, or where standards are advisory. In the United States , the most comprehensive set of Preliminary Remediation Goals (PRGs) is from the Environmental Protection Agency (EPA) Regional Screening Levels (RSLs). A set of standards used in Europe exists and

1974-512: Is likely to come in contact is of particular importance for barriers constructed from fluids which are supposed to set in-situ. EPA emphasizes this compatibility in its guidance documents, noting that thorough characterization of the waste, leachate, barrier material chemistry, site geochemistry, and compatibility testing of the barrier material with the likely disposal site chemical environment are all required." These guidelines are for all materials - experimental and traditional. Thermal desorption

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2068-478: Is no longer any active mining in the Leadville District, over the course of history more than 2800 patented mine claims were filed and the area contains over 1600 prospects, 1300 shafts, and 155 adits . The value of the cumulative production of silver alone from the Leadville mines is estimated to be $ 512 million through 1967 (equivalent to about $ 4.7 billion today). Leadville lies near the center of

2162-578: Is often called the Dutch standards . The European Union (EU) is rapidly moving towards Europe-wide standards, although most of the industrialised nations in Europe have their own standards at present. In Canada , most standards for remediation are set by the provinces individually, but the Canadian Council of Ministers of the Environment provides guidance at a federal level in the form of

2256-622: Is or will be protective of human health ( public health ) and the environment. The last one was published in February 2017. Current actions for long-term protection include assessment of institutional controls for OUs 1, 2, 4 and 10 to guarantee the continue safety levels, implementation of institutional controls for OU-5, possible investigations in OU-3, and updates and implementation of operation and maintenance plans for OUs 5 and 7. The EPA has deleted 9 OUs and proposed to delete several other OUs from

2350-414: Is the impact on local traffic, schools, playing fields, and other public facilities due to the increased population. Dioxins from Union Carbide used in the production of now-banned pesticide 2,4,5-Trichlorophenoxyacetic acid and defoliant Agent Orange polluted Homebush Bay . Remediation was completed in 2010, but fishing will continue to be banned for decades. An EU contract for immobilization of

2444-404: Is the possibility of decreasing anaerobic contaminant destruction natural attenuation where existing conditions enhance anaerobic bacteria which normally live in the soil prefer a reducing environment . In general, aerobic activity is much faster than anaerobic and overall destruction rates are typically greater when aerobic activity can be successfully promoted. The injection of gases into

2538-455: Is then captured and pumped out by extraction wells for further treatment at the surface. Then the water after treatment is discharged into surface water or re-injected into groundwater. In geologic formations that allow delivery of hydrocarbon mitigation agents or specialty surfactants, this approach provides a cost-effective and permanent solution to sites that have been previously unsuccessful utilizing other remedial approaches. This technology

2632-467: Is used for low (below 500 ppmV) VOC concentration vapor streams, oxidation is used for moderate (up to 4,000 ppmV) VOC concentration streams, and vapor condensation is used for high (over 4,000 ppmV) VOC concentration vapor streams. Below is a brief summary of each technology. Using nano-sized reactive agents to degrade or immobilize contaminants is termed nanoremediation . In soil or groundwater nanoremediation, nanoparticles are brought into contact with

2726-659: The Canadian Environmental Quality Guidelines and the Canada-Wide Standards|Canada-Wide Standard for Petroleum Hydrocarbons in Soil . Once a site is suspected of being contaminated there is a need to assess the contamination. Often the assessment begins with preparation of a Phase I Environmental Site Assessment . The historical use of the site and the materials used and produced on site will guide

2820-527: The Colorado Mineral Belt (CMB), a 50-mile-wide (80 km) strip that runs north and south for 300 miles (480 km). Mineralization of the CMB came primarily by way of intrusions of Tertiary Period magmas . The primary ores of the CMB were generally deposited as mixed metal sulfide mineral veins containing pyrite , galena , sphalerite , chalcopyrite , and gold, silver, and copper. During

2914-563: The Colorado Mineral Belt , was the most productive silver-mining district in the state of Colorado and hosts one of the largest lead-zinc-silver deposits in the world. Oro City , an early Colorado gold placer mining town located about a mile east of Leadville in California Gulch , was the location to one of the richest placer gold strikes in Colorado, with estimated gold production of 120,000–150,000 ozt (8,200–10,300 lb; 3,700–4,700 kg), worth $ 2.5 to $ 3 million at

California Gulch - Misplaced Pages Continue

3008-476: The Colorado Silver Boom . Unlike the gold which was in placer deposits , the silver was in veins in bedrock and hard rock mining was needed for recovery of the ore. The city of Leadville was founded near to the new silver deposits in 1877 by mine owners Horace Austin Warner Tabor and August Meyer , By 1878 Leadville had become the county seat of Lake county. The name Leadville probably

3102-678: The Mississippian Leadville Limestone (here a dolomite ), the Devonian Dyer Dolomite , and the Ordovician Manitou Dolomite . Ore minerals are pyrite , sphalerite , and galena , in jasperoid and mangano siderite gangue . In upper levels, the ore minerals are oxidized to cerussite , anglesite , and smithsonite . Leadville was the largest silver-producing district in Colorado. Cumulative production through 1963

3196-565: The US Bureau of Mines to drain the mines of the northern part of the district, and so increase metal production. The tunnel has its outlet north of the town of Leadville, on the East Fork of the Arkansas River. In 1959 the US Bureau of Reclamation bought the tunnel for $ 1.00, as a source of irrigation water. Since March 1992, the Bureau of Reclamation has treated the water flowing out of

3290-527: The last glacial period native gold was freed from the host rock and became available for placer mining . The district is a highly faulted area, intruded with Tertiary quartz monzonite porphyries, on the east side of the Arkansas River graben , part of the Rio Grande Rift system. The silver occurs associated with manganese and lead in veins, stockworks, and manto-type deposits in

3384-748: The 1850s byproduct materials, such as tailings and slag , were left by mining operations. High levels of heavy metals and mine drainage raised concern of high blood lead levels in residents, particularly in children. This hazardous waste and low-pH water also reduced biological diversity and caused stress in the ecosystem , decreasing the trout populations. The most concerning contaminants are arsenic , cadmium , copper , lead , manganese , and zinc . Since 1995, removal and remedial activities have been conducted through federal, state, and PRP actions to consolidate, contain and control more than 350,000 cubic yards of contaminated soils, sediments and mine-processing wastes. Potentially Responsible Parties (PRPs) and

3478-464: The Arkansas River. State and local governments purchased more than 2,300 acres of ranch land that serve as wildlife habitat and recreational resources. A soccer complex was built on part of the site in 2009 and in 2013 a 21,000 square foot skate park opened. In 2014, the Colorado Parks and Wildlife Commission honored the site with a Gold Medal Trout Waters designation. The designation highlights

3572-512: The Bureau of Reclamation issued a report that concluded that a sudden burst of water from the tunnel was unlikely, and that the tunnel posed "no imminent public safety hazard." On 27 February 2008, the US EPA began pumping 150 US gallons (570 L; 120 imp gal) per minute from the tunnel system, to relieve water pressure upstream from the blockage. The water, pumped from the Gaw mine shaft,

3666-468: The EPA work on the cleanup by conducting drainage controls to prevent acid mine runoff, cleanup of residential properties, reuse of slag, and consolidation and containment of contaminated soils, sediments, and mine-processing wastes. The Yak Treatment Plant was also built and it is still in operation. The EPA divided the site into 12 Operable Units (OUs), with the twelfth OU surrounding the whole NPL site and tests

3760-416: The EPA; however, the EPA traditionally has been more cautious about negative externalities that may or may not arise from the introduction of these species. One of their concerns is that the toxic chemicals would lead to the microbe's gene degradation, which would then be passed on to other harmful bacteria, creating more issues, if the pathogens evolve the ability to feed off of pollutants. Entomoremediation

3854-549: The Leadville mining district and the nearby Sherman Mine area saying: Several mining districts surrounding the central Colorado Sawatch Range contain economic deposits hosted by late Mississippian paleokarst features. These are primarily developed in and along the upper surface of the early Mississippian Leadville Formation. Paleokarst features include isolated eaves and sinkholes as well as integrated cavern systems that are mineralized and can be traced from insurgence to outlet. Mining, mineral processing and smelting activities in

California Gulch - Misplaced Pages Continue

3948-669: The NPL. The EPA and the Colorado Department of Public Health and Environment proposed to delete OUs 4, 5 and 7 from the NPL in August 2014. Despite the risk of exposure being low, Pregnant and nursing women, and young children are encouraged to test their blood-lead levels. Lake County continues to offer free blood-lead testing. According to the EPA, the Current Human Exposure status of the California Gulch site

4042-531: The Superfund site designation due to the ongoing cleanup by the EPA. Residents were relieved to no longer be overshadowed by the Superfund stigma. Real estate values have continued to increase, which is in sync with the market in Colorado. According to Trulia, Leadville has seen an increase of $ 46,000 (26%) in the median home price in the last year. Similarly, in the last year the price per square foot has increased from $ 131 to $ 188. These statistics indicate that

4136-529: The USA. Contaminants can be removed from a site or controlled. One option for control are barrier walls, which can be temporary to prevent contamination during treatment and removal, or more permanent. Techniques to construct barrier walls are deep soil mixing , jet grouting , low pressure grouting with cement and chemicals, freezing and slurry walls. Barrier walls must be constructed of impermeable materials and resistant to deterioration from contact with waste, for

4230-717: The Upper Arkansas River's improved water quality and revitalized habitats for trout and other wildlife. California Gulch is one of the many Superfund sites in Colorado . The Superfund program is responsible for cleaning up contaminated land and responding to environmental emergencies, oil spills and natural disasters in the United States. California Gulch was placed on the National Priorities List (NPL) in 1983 due to health risks associated with people ingesting and touching contaminants from

4324-420: The area have produced gold, silver, lead and zinc for more than 130 years. Wastes generated during the mining and ore processing activities contained metals such as arsenic and lead at levels posing a threat to human health and the environment. These wastes remained on the land surface and migrated through the environment by washing into streams and leaching contaminants into surface water and groundwater. The site

4418-460: The area is a major water supply to surrounding homes and businesses, monitoring of lead levels in the groundwater is currently ongoing and thus far indicates that contaminant levels have declined or remained stable. Although risk may be low, blood lead levels are a major concern, especially for pregnant women, nursing mothers, and children as contaminants can cause a variety of adverse health effects such as cell toxicity or neurodevelopmental defects. As

4512-506: The area. There was no local food source and all supplies had to come by either pack mules or the stage coach. Exorbitant prices were being charged for a place to sleep. Leadville is a high mountain town and the winters are long and bitterly cold; many miners died of exposure and starvation. Crime was rampant and lawmen were unable to cope with it. Many small shanty towns grew up around Leadville, including Poverty Flats, Slabtown, Finntown, and Boughtown. The name "Boughtown" referred not only to

4606-630: The assessment strategy and type of sampling and chemical analysis to be done. Often nearby sites owned by the same company or which are nearby and have been reclaimed, levelled or filled are also contaminated even where the current land use seems innocuous. For example, a car park may have been levelled by using contaminated waste in the fill . Also important is to consider off site contamination of nearby sites often through decades of emissions to soil , groundwater , and air. Ceiling dust, topsoil , surface and groundwater of nearby properties should also be tested, both before and after any remediation. This

4700-507: The collapse dam should suddenly fail, as has happened in other mine drainage tunnels in Colorado (such as the Yak tunnel, the Argo Tunnel and the 2015 Gold King Mine waste water spill north of Silverton, Colorado ), a large slug of contaminated water would suddenly flow out of the tunnel, overwhelm the treatment facilities, and flow into the Arkansas River. The rise in water level inside

4794-437: The community should be engaged (at proponent expense if a fee is required). Minutes of meetings including questions asked and the answers to them and copies of presentations by the proponent should be available both on the internet and at a local library (even a school library) or community centre. Incremental health risk is the increased risk that a receptor (normally a human being living nearby) will face from (the lack of)

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4888-402: The community. The proponent needs to learn about "sensitive" (future) uses like childcare, schools, hospitals, and playgrounds as well as community concerns and interests information. Consultation should be open, on a group basis so that each member of the community is informed about issues they may not have individually thought about. An independent chairperson acceptable to both the proponent and

4982-509: The compounds used which vary in viscosity, gel time and density: "The selection of subsurface barriers for any given site which needs remediation, and the selection of a particular barrier technology must be done, however, by means of the Superfund Process, with special emphasis on the remedial investigation and feasibility study portions. The chemical compatibility of the material with the wastes, leachates and geology with which it

5076-627: The contaminant through either in situ injection or a pump-and-treat process. The nanomaterials then degrade organic contaminants through redox reactions or adsorb to and immobilize metals such as lead or arsenic . In commercial settings, this technology has been dominantly applied to groundwater remediation , with research into wastewater treatment . Research is also investigating how nanoparticles may be applied to cleanup of soil and gases. Nanomaterials are highly reactive because of their high surface area per unit mass, and due to this reactivity nanomaterials may react with target contaminants at

5170-495: The contaminants from the groundwater. For petroleum-contaminated sites this material is usually activated carbon in granular form. Chemical reagents such as flocculants followed by sand filters may also be used to decrease the contamination of groundwater. Air stripping is a method that can be effective for volatile pollutants such as BTEX compounds found in gasoline. For most biodegradable materials like BTEX , MTBE and most hydrocarbons, bioreactors can be used to clean

5264-442: The contaminated water to non-detectable levels. With fluidized bed bioreactors it is possible to achieve very low discharge concentrations which will meet or exceed discharge requirements for most pollutants. Depending on geology and soil type, pump and treat may be a good method to quickly reduce high concentrations of pollutants. It is more difficult to reach sufficiently low concentrations to satisfy remediation standards, due to

5358-589: The degradation of the target pollutants. Broad categories of bioremediation include biostimulation , bioaugmentation , and natural recovery ( natural attenuation ). Bioremediation is either done on the contaminated site (in situ) or after the removal of contaminated soils at another more controlled site (ex situ). In the past, it has been difficult to turn to bioremediation as an implemented policy solution, as lack of adequate production of remediating microbes led to little options for implementation. Those that manufacture microbes for bioremediation must be approved by

5452-733: The designation. Even locals who used to overlook the Arkansas river for fishing, now enjoy what is now the longest segment of Gold Medal trout water in CO. The Denver Post quoted Stu Pappenfort, a river ranger with the Arkansas Headwaters Recreation Area, as saying, “When I was a kid and we used to come out here fishing, we skipped over the Arkansas and went to the Taylor and the Gunnison. The heavy metals really impacted

5546-523: The dissolved oxygen content of the groundwater to support microbial degradation of the compound (especially petroleum) by direct injection of oxygen into the subsurface, or the direct injection of a slurry that slowly releases oxygen over time (typically magnesium peroxide or calcium oxy-hydroxide). Solidification and stabilization work has a reasonably good track record but also a set of serious deficiencies related to durability of solutions and potential long-term effects. In addition CO 2 emissions due to

5640-450: The emission is emanating from an area zoned industrial does not mean that in a nearby residential area there should be permitted any exceedances of the appropriate residential standards. Monitoring for compliance against each standards is critical to ensure that exceedances are detected and reported both to authorities and the local community. Enforcement is necessary to ensure that continued or significant breaches result in fines or even

5734-546: The equilibrium of absorption / desorption processes in the soil. However, pump and treat is typically not the best form of remediation. It is expensive to treat the groundwater, and typically is a very slow process to clean up a release with pump and treat. It is best suited to control the hydraulic gradient and keep a release from spreading further. Better options of in-situ treatment often include air sparge/soil vapor extraction (AS/SVE) or dual phase extraction/multiphase extraction (DPE/MPE). Other methods include trying to increase

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5828-518: The excavated material in the case of volatile organic compounds (VOCs) . Recent advancements in bioaugmentation and biostimulation of the excavated material have also proven to be able to remediate semi-volatile organic compounds (SVOCs) onsite. If the contamination affects a river or bay bottom, then dredging of bay mud or other silty clays containing contaminants (including sewage sludge with harmful microorganisms ) may be conducted. Recently, ExSitu Chemical oxidation has also been utilized in

5922-408: The former mining operations found in soil, sediment, surface water, groundwater, liquid waste, solid waste, and sludge . A preliminary estimate in 2006 for the damages to aquatic and terrestrial environments was between $ 53 million and $ 68 million. The second largest settlement in Colorado history was reached in 2008 when the parties agreed on a $ 20.5 million natural resource damages settlement. Since

6016-538: The groundwater conditions. The residential areas of Leadville and Lake County are in OU9. The EPA found concentrations of lead in the soil in some areas that exceeded the soil action levels of 3,500 parts per million, causing risk of lead poisoning in the population. EPA completed various Five-Year Reviews with the purpose of evaluating the implementation and performance of the Environmental remedy to determine if it

6110-573: The groundwater may also cause contamination to spread faster than normal depending on the hydrogeology of the site. In these cases, injections downgradient of groundwater flow may provide adequate microbial destruction of contaminants prior to exposure to surface waters or drinking water supply wells. Migration of metal contaminants must also be considered whenever modifying subsurface oxidation-reduction potential. Certain metals are more soluble in oxidizing environments while others are more mobile in reducing environments. Soil vapor extraction (SVE)

6204-494: The important challenges currently limiting nanoremediation technologies include identifying coatings or other formulations that increase dispersal of the nanoparticle agents to better reach target contaminants while limiting any potential toxicity to bioremediation agents, wildlife, or people. Bioremediation is a process that treats a polluted area either by altering environmental conditions to stimulate growth of microorganisms or through natural microorganism activity, resulting in

6298-423: The land surface and migrated through the environment by washing into streams and leaching contaminants into surface water and groundwater. Investigation of the site began in the mid-1980s. California Gulch was designated a Superfund Site in 1983, shortly after the Environmental Protection Agency created the program. In 1998, EPA and the state of Colorado signed agreements to provide public access to open space near

6392-421: The levels of dust, noise, odour, emissions to air and groundwater, and discharge to sewers or waterways of all chemicals of concern or chemicals likely to be produced during the remediation by processing of the contaminants. These are compared against both natural background levels in the area and standards for areas zoned as nearby areas are zoned and against standards used in other recent remediations. Just because

6486-468: The lifespan of the barrier wall. It wasn't until the use of newer polymer and chemical grouts in the 1950s and 1960s that Federal agencies of the US government recognized the need to establish a minimum project life of 50 years in real world applications. The Department of Energy is one US government agency that sponsors research to formulate, test and determine use applications for innovative polymer grouts used in waste containment barriers. Portland cement

6580-624: The many pine trees that grew in the area, but to lodgings the miners built of four posts covered with pine boughs. In 1893, the repeal of the Sherman Silver Purchase Act caused a panic in Leadville and in all of Colorado's silver camps. The price of silver fell rapidly and eventually many of the silver mines closed. Mining companies came to rely increasingly on income from the lead and zinc . The Sherman Mine produced over 10 million ounces (620,000 pounds; 280,000 kilograms) of silver, mostly between 1968 and 1982, with

6674-435: The mines extended deeper, keeping the water pumped out of the workings became a major expense. To more economically drain the mines, two tunnels were driven to allow the water to drain by gravity. Water from both tunnels ultimately flows into the Arkansas River . The Yak tunnel, 3.5 miles (5.6 km) long and built between 1895 and 1923 to drain the southern part of the district, has its outlet in California Gulch east of

6768-446: The potentially responsible parties have involved drainage controls to prevent acid mine runoff, consolidation and capping of mine piles, cleanup of residential properties and reuse of slag. As of September 2011, most of the cleanup had been completed so current risk of exposure is low, although pregnant women, nursing mothers and young children are still encouraged to have their blood-lead levels checked. As in many mining districts, as

6862-465: The remediation of contaminated soil. This process involves the excavation of the contaminated area into large bermed areas where they are treated using chemical oxidation methods. This is used in removing non-aqueous phase liquids (NAPLs) from aquifer. This is done by pumping surfactant solution into contaminated aquifer using injection wells which are passed through contaminated zones to the extraction wells. The Surfactant solution containing contaminants

6956-406: The removal, treatment and containment of pollution or contaminants from environmental media such as soil , groundwater , sediment . Remediation may be required by regulations before development of land revitalization projects. Developers who agree to voluntary cleanup may be offered incentives under state or municipal programs like New York State's Brownfield Cleanup Program. If remediation

7050-405: The site should have a safety induction personalised to their involvement with the site. Local communities and government often resist the rezoning because of the adverse effects of the remediation and new development on the local amenities. The main impacts during remediation are noise, dust, odour, and incremental health risk. Then there is the noise, dust, and traffic of developments. Then, there

7144-566: The size of the fish. There was a good number of them, but not the ones you wanted to hold up in the picture. So we skipped over it.” As a result of the clean up efforts and the Gold Medal designation, there were over 100,000 anglers fishing the Arkansas between Leadville and Parkdale in 2012. 39°13′27.96″N 106°20′58.09″W  /  39.2244333°N 106.3494694°W  / 39.2244333; -106.3494694 Leadville mining district The Leadville mining district , located in

7238-460: The spill has not had a significant adverse impact on the growth for Leadville; however, it also highlights the need for ongoing monitoring and sustainable solutions for existing and expanding residents. The Arkansas River was named a “gold medal” trout stream in January 2014. The designation significantly helped tourism revenue for the town. Guides reported a 25% increase in trout guided tours after

7332-728: The surface as well as extraction of contaminated groundwater and treatment at the surface. In-situ methods seek to treat the contamination without removing the soils or groundwater. Various technologies have been developed for remediation of oil-contaminated soil/sediments. Traditional remediation approaches consist of soil excavation and disposal to landfill and groundwater "pump and treat". In-situ technologies include but are not limited to: solidification and stabilization , soil vapor extraction , permeable reactive barriers, monitored natural attenuation, bioremediation - phytoremediation , chemical oxidation, steam-enhanced extraction and in situ thermal desorption and have been used extensively in

7426-631: The then-price of $ 20.67 per troy ounce. Cumulative production through 1963 was 240 million troy ounces (16 million pounds; 7.5 million kilograms) of silver , three million troy ounces (210 thousand pounds; 93 thousand kilograms) of gold , 987 million tonnes (2.2 trillion pounds; 987 billion kilograms) of lead , 712 million tonnes (1.6 trillion pounds; 712 billion kilograms) of zinc , and 48 million tonnes (110 billion pounds; 48 billion kilograms) of copper . The district also produced byproduct bismuth , and iron- manganese ore. Gold

7520-500: The town of Leadville. The tunnel became part of the California Gulch Superfund site in 1983. In October 1985, a large surge of water from the Yak tunnel reached the Arkansas River, and elevated the dissolved metals content of the river for tens of miles downstream. Water flowing from the tunnel has been treated by its owner, ASARCO, since June 1991, to remove metals. The Leadville tunnel was started in 1943 by

7614-546: The trail follows old mining-camp railbeds. Several signs along the way provide historical snippets about Leadville's colorful past. The "Route of the Silver Kings" is a driving tour of the 20-square-mile (52 km ) historic mining district surrounding Leadville. The tour includes mines, power plants, ghost towns and mining camps. The National Mining Hall of Fame and Museum occupies 71,000 square feet (6,600 m ). Major exhibits include an elaborate model railroad ,

7708-484: The tunnel has caused water with high concentrations of dissolved metals to leak out to the ground surface through springs. Opinions as to the threat posed varied widely. County Commissioner Mike Hickman said "If it blows, it could be a national catastrophe, not only to Leadville and Lake County but to the entire Arkansas River." On the other hand, Leadville Mayor Bud Elliott stated "This is what happens when you create an emergency when there isn't one." On June 30, 2008,

7802-484: The tunnel, to remove dissolved metals and bring the water quality into compliance with the Clean Water Act. Collapses within the tunnel that began in 1995 partially blocked flow, and have created a large reservoir of an estimated one billion US gallons (3.8 billion litres; 830 million imperial gallons) of water within the tunnel behind the collapse. In February 2008, concerns became public that if

7896-459: The use of cement are also becoming a major obstacle to its widespread use in solidification/stabilization projects. Stabilization/solidification (S/S) is a remediation and treatment technology that relies on the reaction between a binder and soil to stop/prevent or reduce the mobility of contaminants. Conventional S/S is an established remediation technology for contaminated soils and treatment technology for hazardous wastes in many countries in

7990-847: The user to view additional information. One such tool is TOXMAP , a Geographic Information System (GIS) from the Division of Specialized Information Services of the United States National Library of Medicine (NLM) that uses maps of the United States to help users visually explore data from the United States Environmental Protection Agency 's (EPA) Superfund and Toxics Release Inventory programs. Remediation technologies are many and varied but can generally be categorized into ex-situ and in-situ methods. Ex-situ methods involve excavation of affected soils and subsequent treatment at

8084-616: The world. However, the uptake of S/S technologies has been relatively modest, and a number of barriers have been identified including: New in situ oxidation technologies have become popular for remediation of a wide range of soil and groundwater contaminants. Remediation by chemical oxidation involves the injection of strong oxidants such as hydrogen peroxide , ozone gas, potassium permanganate or persulfates. Oxygen gas or ambient air can also be injected to promote growth of aerobic bacteria which accelerate natural attenuation of organic contaminants. One disadvantage of this approach

8178-496: Was 240 million troy ounces (16 million pounds; 7.5 million kilograms) of silver, three million troy ounces (210 thousand pounds; 93 thousand kilograms) of gold, 987 million tonnes (2.2 trillion pounds; 987 billion kilograms) of lead, 712 million tonnes (1.6 trillion pounds; 712 billion kilograms) of zinc, and 48 million tonnes (110 billion pounds; 48 billion kilograms) of copper. Geologist R. Mark Maslyn describes

8272-416: Was added to the U.S. Environmental Protection Agency (EPA) National Priorities List in 1983,. Investigation of the site began in the mid-1980s. Since 1995, EPA and the potentially responsible parties have conducted removal and remedial activities to consolidate, contain and control more than 9,400,000 cubic feet (350,000 cu yd) of contaminated soils, sediments and mine-processing wastes. Cleanups by

8366-427: Was chosen for the town because lead was the major mineral in both the placers and in the lode mines. By 1880, millions of dollars were being made and Leadville became one of the world's largest silver camps with a population of over 40,000. Leadville became Colorado's largest mining camp and the town was second only to Denver . Leadville became overcrowded, unable to support the hundreds of miners that were flooding into

8460-403: Was clean enough to discharge to the Arkansas River without treatment. Meanwhile, the EPA drilled a new well into the tunnel system; a pump test was completed in early June 2008 to determine optimal pumping rate. The Mineral Belt National Recreation Trail is an 11.6-mile (18.7 km) all-season biking/walking trail that loops around Leadville and through its historic mining district. In part

8554-456: Was discovered in the area in late 1859, during the Pike's Peak Gold Rush . However the initial discovery, where California Gulch empties into the Arkansas River , was not rich enough to cause excitement. On April 26, 1860, Abe Lee made a rich discovery of placer gold in California Gulch, about a mile east of Leadville, and Oro City was founded at the new diggings. By July 1860 the gold rush

8648-467: Was dug in 1877 to provide water for hydraulic mining , but the hydraulic mining was reported to be unsuccessful. In 1874, gold miners at Oro City had an assay done on the heavy, black sand that had been impedeing their placer gold recovery and found that it was the lead mineral cerussite , that carried a high content of silver . Prospectors traced the cerussite to its source, and by 1876 had discovered several lode silver-lead deposits, setting off

8742-446: Was on; the town and surrounding area grew to a population of 10,000 and an estimated $ 2 million in gold (equivalent to $ 70 million today) was taken out of California Gulch and nearby Iowa Gulch by the end of the first summer. But within a few years the richest part of the placers had been exhausted and the population of Oro City dwindled to only several hundred. Many claims were consolidated, and worked by ground sluicing . A ditch

8836-399: Was used in the past, however cracking and poor performance under wet-dry conditions at arid sites need improved materials to remedy. Sites that need remediation have variable humidity, moisture and soil conditions. Field implementation remains challenging: different environmental and site conditions require different materials and the placement technologies are specific to the characteristics of

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