Monday, July 13, 2009

Asbestos Contaminated Soils Up-Date

Asbestos Testing and Treatments in Soils.

Spokane Being Tested for Asbestos


As a result of the public health emergency declared in Libby, Montana in June, which resulted from former vermiculite mining, a Spokane (Washington) neighborhood is now undergoing asbestos testing.


asbestos-laden dust


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 When we hear the word "asbestos" you often think back on the controversy of the late 1970’s when it became common knowledge that asbestos was indeed a human health hazard. Asbestos however, is still a relevant hazard today in a number of different capacities. While most asbestos containing products were banned by the Consumer Product Safety Commission and regulated by the Environmental Protection Agency, unfortunately it still exists in hundreds of older products as well as in trace amounts in newly manufactured products. Among new products that may still contain asbestos are soil retention enhancers, particularly vermiculite.1

 Asbestos is a term used for several naturally-occurring fibrous minerals.
Asbestos most commonly occurs in ultramafic rock that has undergone partial
or complete alteration to serpentine rock, and often contains chrysotile asbestos.
Another form of asbestos, tremolite, can be found associated with ultramafic rock,particularly near faults.
 Asbestos fibers are released from rock when it is crushed or broken and through natural weathering processes. The fibers are tiny and may be invisible to the naked eye. Since this rock may be present in the soils around your home, or may have been used in the past on your driveway or walkway, there is a potential for asbestos exposures where you live. This could happen through routine activities that crush asbestos-containing rock or create dust in soils that contain asbestos fibers.

 Over the last five to ten years, the remediation and redevelopment of contaminated property, commonly called "brownfields," has become more prevalent, in part due to both federal and state legislation which makes remediation of contaminated property easier, and provides additional liability protections for those undertaking cleanups.
 A "brownfield" is generally defined as "real property, the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant."
 Risk Assessment has become the essential tool for site investigations as the Environmental Protection Act (EPA) Part IIA requires a risk based approach to be used when assessing potentially or actually contaminated sites. This risk based approach is also required as part of the planning process for new developments.
Asbestos is a routine analyte in contaminated land investigations and is a potential contaminant for a range of historic land uses due to its widespread use as described in CLR 8: Potential Contaminants for the Assessment of Land and historic Department of Environment Industry Profiles.

 Naturally occurring asbestos (NOA) includes fibrous minerals found in certain types of rock formations. (NOA) can take the form of long, thin, separable fibers. Natural weathering or human disturbance can break NOA down to microscopic fibers, easily suspended in air.

 There is no health threat if (NOA) remains undisturbed and does not become airborne. When airborne (NOA) is inhaled, these thin fibers irritate tissues and resist the body's natural defenses. Asbestos, a known carcinogen, causes cancers of the lung and the lining of internal organs, as well as asbestosis and other diseases that inhibit lung function. Covering (NOA) with clean soil or planting grass reduces exposure.

 Often soil and vermiculite material will contain asbestos fibers either as naturally occurring asbestos in rock, such as serpentine, or as contamination from asbestos removal activities. The need to identify the presence of asbestos fibers in & of these materials may often be necessary prior to alteration, remediation, or removal of such material.
 Serpentine rock is often a component of road material, parking lots, playground surfaces, waste piles, and general excavation and construction sites.

 Workplace exposure to asbestos is heavily legislated and a clear regime of guidance exists for contamination on land via the EA's CLR/CLEA publications.3
 But there is no standard remedial level for asbestos in soils or for airborne monitoring for asbestos in the environment.
 Once free, asbestos fibers may stay in the soil or remain airborne for a long time.2

WHAT TO LOOK FOR ...


 Some examples of these activities are:
  • Driving over areas surfaced with
    ultramafic or serpentine rock
  • Rototilling, plowing the ground, or using a shovel
  • Riding horses or moving livestock
  • Construction activities, such as pool installationUsing a leaf blower to clean sidewalks


 For construction, paving, school, development, excavation, mining, and other related companies, the CARB 435 method4 allows clients to check for asbestos with accuracy before they excavate

 These technical and regulatory guidelines were developed to provide all stakeholders(technology users, technology developers, the regulated community, and the public) with some degree of predictability and consistency in technology deployment from state to state.
 States reserve the right to go beyond these guidelines, but should have a rationale for doing so.5

Health Hazard

 This health consultation has been prepared in response to the request made by the City of Nashau to the New Hampshire Department of Health and Human Services(DHHS) for assistance in evaluating the health hazard associated with potential exposure to asbestos contaminated soils excavated during a public works project in the City of Nashua. Specifically, this document evaluates the soil and air sampling data that was collected to evaluate the potential release of asbestos fibers to the community during removal activities at the Sargeant Avenue and Broad Street sites.
 This health consultation has been prepared by the New Hampshire Department of Health and Human Services, Office of Community and Public Health, Bureau of Environmental and Occupational Health (DHHS) through a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR).6

 The concept of reducing soil contamination through the use of soil washing and particle size separation is based on the finding that most organic and inorganic contaminants tend to bind preferentially to clay, silt, and organic soil particles.

 In the washing process, the fine clay and silt particles are separated from the coarser sand and gravel soil particles. The separated fines and contaminants are dewatered into a dry filter cake suitable for off-site disposal. Additional treatment of the sand and gravel fractions maybe incorporated into the process as needed. The cleaned sand and gravel fraction can be returned to the site.

 From a feed stream of basically granular soils, the product streams would include contaminated coarse organics, clean coarse and sand products, contaminated fine organics and contaminated silts and clays. Water used within the system is continuously recycled as part of the process.

 Contaminants treatable by soils washing include
  1. Petroleum
  2. Hydrocarbons
  3. Cyanides
  4. PAH
  5. Organotins
  6. Heavy Metals
  7. Pesticices
  8. PCB
“Soil washing can be used for a wide range of contaminants including metals, organics and asbestos." Erik Groenendijk of ART Engineering, LLC explains.
 Mr. Groenendijk continues "The effectiveness of soil washing is based on separation of contaminants in a water based process. In principle asbestos can be separated from the soil in the washing process depending on the physical form of the asbestos and soil type. The optimal remediation and soil treatment approach for each site depends on project specific conditions and is determined in a technical feasibility study."

 Because of the wide variability among states, these guidelines do not include any emission criteria for air, or cleanup criteria for soil or water.

A Work in Progress
7
 Work is ongoing at the former Vospers shipyard (Woolston Riverside, Southampton) to develop a solution for contamination issues that include asbestos in soils. CampbellReith12, on behalf of the South East England Development Agency (SEEDA), has implemented a series of trials and research experiments to help clarify the level of risk presented by varying levels and types of asbestos in soils.

Asbestos-contaminated soil cleanup guidance8
 The Colorado Department of Public Health and Environment's Hazardous Materials and Waste Management Division (the Division) has established specific management requirements for asbestos-contaminated soil under Section 5.5 of the Regulations Pertaining to Solid Waste Disposal Sites and Facilities (6 CCR 1007-2), effective April 30, 2006.

Fungi iron-out asbestos pollution

 Bioremediation might make fibre-contaminated soil safer.
 "Fungi may help decontaminate asbestos-polluted soils," say Silvia Perotto and co-workers at the University of Torino. They have found a fungus that takes the toxic bite out of asbestos fibres.9

References

  1. Asbestos Hazard

  2. Asbestos-Containing Rock & Soil

  3. Asbestos Testing and Treatments in Soils. A Work in Progress

  4. Carb435

  5. Asbestos Testing and Treatments in Soils

  6. Background & Statement of Issues

  7. A Work in Progress

  8. Background & Statement of Issues

  9. Fungi iron-out asbestos pollution

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