Loading AI tools
The Atlas Asbestos Mine is a Superfund site located in the Fresno County eighteen miles northwest of Coalinga, California. The mine started operating in 1963, covering 435 acres of a large naturally-occurring asbestos deposit. The mine closed in 1979 and was placed in the EPA's National Priorities List (NPL) in 1983 due to the pollution of asbestos in the surrounding soil, air and water creating potential health hazards for local populations and environment.
Asbestos is a defined set of 6 fibrous silicate minerals that are separated into two classes: serpentine and amphibole. Physical properties of asbestos includes an inability to dissolve in water and a high resistivity to heat and biological/chemical degradation making it a valuable product for commercial use. A general chemical formula of amphioble is (Na,K)0-1(Ca,Na,Fe,Mg)2(Mg,Fe,Al)5(Si,Al)8O22(OH)2. Amphiboles are double-chain silicates; their fibers are brittle, needle shaped and are not widely used in commercial products. Serpentine asbestos, the most common of the two, mainly contains the mineral Chrysotile and accounts for 95% of the asbestos found in the United States. Chrysotile has a chemical formula of Mg3Si2O5(OH)4, a sheet silicate and its fibers are more flexible than an amphibole fiber. As desirable as these products are for commercial use they are hazardous and are considered to be human carcinogens.
Asbestos fibers (SEM micrograph)
Health Hazards
Asbestos was commonly used in different commercial products, prior to the EPA banning its use in 1989 , making it easy for people to be exposed to it in their homes and workplaces. The two methods of exposure are inhalation and ingestion. When asbestos products release their fibers into the air it is easily breathed in and released back out, but some fibers become trapped in lungs causing scarring and inflammation. Ingestion of asbestos is primarily through the ingestion of soil that contains asbestos and by indirect ingestion of the inhaled asbestos.[1] The risk of getting asbestos-related diseases depends on five factors[2]
- Exposure Concentration
- Exposure Duration
- Exposure Frequency
- Size, shape and chemical makeup of asbestos fibers
- Individual Risk Factors (i.e Tabacco use)
- Asbestos in lung tissue
Asbestos-related diseases
In the United States, the number of deaths by asbestos-related diseases is around ten thousand people per year. Diseases related to asbestos include:[3] [4]
- Asbestosis: the fine asbestos fibers are easily inhaled and can cause a number of respiratory complaints, including a potentially serious lung fibrosis called asbestosis.
- Cancer: mesothelioma, which refers to asbestos cancer, is caused by asbestos exposure. In addition, many cancers potentially associated with exposure to asbestos, such as gastrointestinal cancer, colorectal cancer, breast cancer, prostate cancer, Hodgkin's Lymphoma, non-Hodgkin's Lymphoma, Ovarian, and leukemia.
- Asbestos warts: caused when the sharp fibers lodge in the skin and are overgrown causing benign callus-like growths.
- Pleural plaques: discrete fibrous or partially calcified thickened area which can be seen on X-rays of individuals exposed to asbestos. They do not become malignant nor normally cause any lung impairment.
- Diffuse pleural thickening: similar to above and can sometimes be associated with asbestosis. Usually no symptoms shown but if extensive can cause lung impairment.
Pollution
The pollution from the Atlas asbestos mine is generated by three open pit asbestos mines, an abandoned mill building, a settling pond and debris.[5] The contaminants are drained into Los Gatos Creek(a tributary to the Ponding Basin).During floods a detention basin would store the asbestos laden water preventing it from reaching the California Aqueduct; however, over time the build-up of sediments reduce the storage capacity of the basin allowing asbestos fibers to enter the aqueduct. It was not until 1980 that the metropolitan water district(MWD) of southern california measured elevated levels of asbestos in the water that reached 2500 millions of fibers per liter.[6] In 2004, the Department of Water Resources decided to take action and enlarged the detention basin to store more water and prevent further contamination of asbestos fibers in the aqueduct.
Asbestos fibers can also be found in air and soils which can endanger the lives of people in the region. They can be released into the air and soil through two ways, human activity and rock weathering processes. When the EPA conducted a sampling of airborne asbestos in 1987 in Coalinga they found that there was 1-50% of Chrystolite asbestos, when they sampled soil they found less than 1 to 98% of soil in the area was contaminated. [7] [8] The soil near the city of Coalinga also found traces of chromium and nickel. [9]
Remediation
The EPA began initial investigations of the site in 1984 in order to determine the best course of action in minimizing harm of human health and protecting the environment.[10]
In 1991, The EPA finished assessing the asbestos contamination in the surface of the mine site. It was established that they would approach the clean up process in two OU's (Operating Units), which are focused study areas in which specific actions are taken in order to address the different hazards caused by asbestos contamination. These two OU's are the Atlas Asbestos Mine OU and the City of Coalinga OU, which together consist of the cleanup process of the whole Atlas Asbestos Mine Superfund Site.[11]
The Atlas Asbestos Mine OU was focused on clean up of surface asbestos and mining tailings at the site of the mine itself. Methods of remediation consisted mainly of building diversions to prevent streams from flowing through asbestos contaminated sites and mining tailing, thus minimizing the amount of asbestos eroding and contaminating water sources. In addition, sediment trapping dams were built and slope stabilizers were implemented on waste piles. Fences were built to limit access to the area. The primary cleanup processes and construction involved in remediation occurred between 1994 and 1996. Since the primary clean up process, a re-vegetation pilot study has been conducted in 1999, and the Five Year Report in 2001 showed signs of erosion in the access road to the site. Thus a new route was suggested to be explored.
Another issue that arose from asbestos contamination was the potential danger of recreational activities occurring in the nearby Clear Creek Management Area (CCMA). This is a surrounding area of the mine managed by the Bureau of Land Management (BLM) where off-road driving, camping, and hiking were proven to cause higher asbestos levels in the air. Tests of air samples showed that long term activities caused greater risk of cancer. The area was immediately closed by the BLM for further discussion of remediation methods. [12]
The City of Coalinga OU was focused on remediation of asbestos that had been transported to mills or stored. The cleanup area consisted of 107 acres of contaminated soil within the city of Coalinga. Beginning in 1989, over 200,000 cubic yards of asbestos, nickel and chromium-contaminated soil and building debris were consolidated to be disposed and contained in an underground waste management unit (WMU). The area of the WMU was capped with an impermeable cover, and is to be continuously monitored along with the groundwater and air. The area excavated was regraded. Cleanup of this sector occurred between 1990 to 1993.
Status Quo
The Atlas Asbestos Mine Superfund Site was removed from the National Priorities List (NPL) on April 24, 1998, based on the fact that responsible parties have taken appropriate action in preventing further environmental damage of the area.[13] However, as long as hazardous materials remain at the site above levels considered safe by the EPA, reviews must occur every five years.
The first five-year report was conducted in 2001.
The second five-year report of the site was completed on September 28, 2006. Due to regulation changes to the levels of asbestos allowed in places of contamination in the soil around the underground waste management unit (WMU), additional remedial action was recommended to assure the safety of the area. After additional tests conducted by the EPA on water and air samples, results showed that cleanup activities were still protective of human health as well as the environment. Thus it was established that cleanup has been completed successfully in the Atlas Asbestos Mine site.
The next five-year review will be completed by September 2016.
Wikiwand in your browser!
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.
