Alternative Abatement Methods
The Centers for Disease Control (CDC) explains that an initial study of asbestos abatement techniques in 1984 exposed several unique and alternative methods of controlling and abating asbestos-containing materials. Two common methods involve wetting the asbestos materials, which reduces their ability to become airborne, and employing negative air pressure, which removes the contaminated air from a space and draws clean air back in. The contaminated air is then filtered through high efficiency particulate air (HEPA) filters in order to contain and reduce atmospheric release. The CDC explains that evaluating such abatement techniques is important because these generally represent some of the most effective release and exposure controls. Below are several other techniques that prove effective in the abatement of asbestos.
Glove Bag Abatement
This form of abatement is often used as a source control during the removal of pipe lagging. These large plastic bags contain long gloves which are sealed into the body of the containment receptacle. Workers seal the bags around the area containing asbestos that needs to be removed and use tools inside the bag to detach asbestos-containing pipe lagging or other materials. The debris then collects at the bottom of the bags, which hang on the underside of pipes and other asbestos-containing structures. After the surface has been completely scoured of all asbestos traces, the contained material can be disposed in accordance with state and nationwide standards. This alternative form of abatement allows for the control of water, as well as airborne particulates. This water control is important, as abatement often occurs in mechanical rooms containing equipment susceptible to water damage or equipment that might present a safety hazard when wet.
This alternative means of abatement can also be used for general maintenance and can often be used without any other form of containment, such as the costly and time-consuming total area enclosure with plastic barriers and negative air pressure that is frequently used. Although a basic pattern is generally followed for this method of attaching the glove bag, removing insulation, cleaning the surfaces, and removing the protective bag, some details may differ based on the preference of the on-site abatement manager. However, glove bag removal acceptance criteria remain the same as gross removal, which states that no visible residue is to remain on abated surfaces. In addition, remaining, adjacent material needs to be protected with mastic and adhesive cloth to ensure it is properly protected.
Mini Enclosure Abatement
Although no clear standards differentiate a “mini-enclosure” from conventional enclosures, several general features do help distinguish the two. Mini-enclosures have no shower or separate load-out for removed material. Instead, a mini-enclosure is comprised of just two rooms: the actual work chamber where asbestos-containing materials are removed and a changing room, where contaminated clothing is removed. Further decontamination is expected to take place in another location.
Mini-enclosures are placed under negative air pressure, which is usually achieved through the use of a HEPA-filtered vacuum outside of the enclosure. Mini-enclosures may also be used to surround glove-bag abatement areas to add further protection. Abatement limited to a very small area for a very specific purpose, called “spot removal,” is also often performed with mini-enclosures. This form of removal may be performed to prepare for an abatement project or to remove enough asbestos-containing material from an area to construct a critical barrier separating a toxic and clean space. Mini-enclosures may also be used to remove asbestos materials so further renovation work can be performed.
According to OSHA regulations, a mini-enclosure can accommodate no more than two individuals, meaning this enclosure is markedly smaller than conventional enclosures. Often freestanding and remaining in an area for a short period of time, work in these structures is often performed in short stints of one night or a single work shift. The amount of materials that can be removed with such a structure is reduced, though more than one mini-enclosure can be positioned throughout an abatement area. Furthermore, these enclosures can be disassembled and cleansed to allow for the abatement of more than one area with a single containment structure.
Dismantling Components with Intact Asbestos Containing Materials
An additional method of removing asbestos-containing materials consists of leaving the asbestos-containing materials on the component and removing the entire structure from the area. These components are then disposed of in a safe manner consistent with state and national standards. Some of these asbestos-tainted components may even be flattened to reduce their waste volume.
Although often more time-effective than independently scraping off or removing individuals pieces of a component, dismantling also presents several limitations. Firstly, asbestos-containing materials may easily fragment from these components unintentionally during removal, especially with large items that are difficult to transport. Furthermore, some items contain small amounts of asbestos that need to be removed before the component can be detached, which can actually slow the process and increase abatement difficulties. Finally, more waste material is sent to the landfill when entire components are removed, increasing the removal and environmental costs.
- Centers for Disease Control
- Oberta, Andrew F. (2005). Asbestos Control: Surveys, Removal, and Management (2nd ed.). West Conshohocken, PA: ASTM International.