Asbestos waste can be divided into five categories:
Hard Waste
Investment in grinding equipment is, however, not the only way to reduce the amount of hard waste produced. Better production control and better housekeeping should be considered first, so as to reduce to the absolute minimum, the quantity of hard waste produced. Only then should recycling, through grinding, be considered to further reduce the amount of waste to be disposed of.
If production facilities or the product itself does not permit recycling, the waste should be stored in containers close to the production area generating the waste and in such a manner to ensure that it will not be abraded or crushed while awaiting disposal.
Technologies have been developed to reduce the volume and weight of sludge by dewatering prior to transport to the disposal site. This not only reduces transportation and disposal costs, but also increases the stability of the disposed waste. Equally important, dewatering allows the disposal of larger quantities of sludge in the same (usually limited) space in the disposal site.
The slurry should be loaded into specially designed carriers or other containers to ensure that no spillage occurs.
Friable waste should be put in properly labelled, translucent bags (polyethylene) with a minimum thickness of 6 mil. Bags should be sealed immediately after filling, and stored in an area where they cannot be broken or otherwise disturbed.
Where activities involving the disturbance of friable waste are likely to generate airborne fibres at concentrations which exceed permissible exposure limit values, workers should be equipped with appropriate personal protective equipment.
For disposal, bags should be sealed in an impermeable bag and deposited in an appropriate landfill. A further method of plastic bag disposal is melting. By melting the empty bags and wrappers, the asbestos residue becomes embedded in the melted plastic.
Under no circumstance should bags be reused for packing or other purposes.
Operation in a fully closed circuit (zero waste) is not a myth but a real possibility. This possibility is not open to each and every plant. In the case of asbestos-cement plants, an important factor is the chemical composition of the cement which is used in the production process.
However, discharge of process water can, in most cases, be drastically reduced through good housekeeping and stringent control of unnecessary clean water inputs into the production circuit.
Asbestos waste, whether loose or in sealed containers, should be transported to the disposal point in such a way that no asbestos dust is emitted into the air.
In the event of accidental spillage (for example, as the result of a road accident) during transport to the disposal site, action appropriate to the extent of the spillage should be taken immediately.
Where the amount of spilled material is small, the waste should be collected into its original receptacle and reloaded without delay.
If the spillage is substantial and the material dusty, it should be wetted, if practicable, and covered immediately. The material should then be removed. During this process appropriate safety precautions, which may include the use of protective clothing and respiratory equipment, should be taken.
Waste disposal requirements depend on whether the asbestos waste is friable or non-friable. Most jurisdictions in North America do not consider non-friable, or hard waste, as a hazardous waste. As a non-hazardous waste, non-friable asbestos waste can be disposed of in any landfill, including municipal landfills that handle everyday household waste.
The U.S. EPA requires a number of precautions in collecting friable asbestos waste, transporting it, and assuring it is placed in an appropriate landfill. Those precautions include:
1. Wetting the waste;
2. Discharging no visible emissions during collection and transfer of the waste to the disposal site;
3. Transporting the waste in vehicles marked as containing asbestos;
4. Preparing asbestos waste shipment records which are to be returned to the company which generated the waste to provide assurance that it was properly delivered to a regulated waste site; and
5. Depositing the waste at a regulated waste disposal site that:
€ has no visible emissions, or covers the asbestos waste daily with at least 6 inches of non-asbestos materials or an effective dust suppression agent, and which, upon permanent closure, also covers the waste with vegetation or (in desert areas) at least three inches of crushed rock; and
€ has warning signs or fences.
In short, regulated asbestos waste (i.e., waste containing more than 1% asbestos that is friable or likely to become friable) must be handled carefully to assure no visible emissions while being transported or after it is deposited in an asbestos landfill. No precautions with respect to migrating to ground-water (as are required for other hazardous wastes under RCRA) apply to such an asbestos waste disposal site.
1. Before a site is used for the disposal of asbestos waste, care should be taken to establish that the site is both suitable and acceptable for the purpose;
2. The disposal site chosen should have vehicular access to the working face, or to a hole or trench dug to receive the asbestos waste;
3. The waste should, wherever practicable, be deposited at the foot of the working face of the landfill site or at the bottom of an excavation dug for it;
4. Where the waste has to be deposited from above the working face, or into an excavation, care should be taken to prevent spillage from bags;
5. When deposited, all waste other than high-density waste should be covered to an acceptable depth (for example 20-25cm [8-10 in.]) as soon as possible. No asbestos waste should be left uncovered at the end of a working day;
6. If wet waste is deposited, it should be covered in the same way as dry waste to prevent the escape of asbestos dust on drying out;
7. Wet pits should not normally be used for the disposal of any asbestos waste other than high-density material;
8. Where high-density waste is deposited on a dry site, care should be taken to ensure that it is not ground to dust by the passage of vehicles over it.
Any asbestos waste awaiting disposal should be identified by means of a label on the corresponding container. A register should be kept with mention of volumes, composition and localization of asbestos-containing waste.
Where vehicles and reusable receptacles and covers have been in contact with asbestos waste, they should be cleaned after use by means of a vacuum cleaner or by an alternative dustless method.
If a waste disposal contractor is employed, the relevant sections of the Code should be incorporated in the contract.
The contract should state that the contractor is responsible for ensuring that safety measures are observed at the disposal site.
Periodic checks should also be made by the undertaking to ensure that the contractor is observing the Code.
8 - WASTE HANDLING
Disposal of asbestos waste is becoming increasingly expensive and subject to more and more stringent regulations. In these circumstances, the best solution is to avoid, or minimize to the extent possible, the amount of waste created by adopting the most efficient production techniques, including recycling. Alternatively, some asbestos waste (e.g. brakelinings) can be used as a raw material for other asbestos-using industries (e.g. roof coatings). Where it is impossible to avoid the creation of waste, it must be handled, transported and disposed of in accordance with national regulations or international practices.
8.1 - TYPES OF WASTE
Included in this category are the following: bonded asbestos, asbestos-cement, jointings, bitumastic rubber residues, offcuts and rejects. Hard waste grinding techniques are well established and reliable equipment is available on the market. A typical two-stage grinding plant capable of producing two tonnes of ground, hard waste per hour would cost approximately U.S.$35,000.
Wet Waste (sludge or slurry)
Given the fact that sludge recycling is problematic, it is of paramount importance to avoid excessive sludge production in the first place. If sludge production is unavoidable, recycling possibilities must be explored. Various techniques have been developed to this end. All have attempted to re-use sedimentation basins and improve the raw material yield of the process.
Friable Waste
Friable waste is waste capable, when dry, of being crumbled, pulverized or reduced to powder by hand pressure. Sources of friable waste in a factory setting include: fine dust produced from debagging facilities, material conveyors, mixing equipment or such processes as sawing, sanding or machining, as well as waste products from the bag house or industrial ventilation systems. On construction sites, waste from friable insulation removal activities is a major source of asbestos waste. Other sources of friable waste include: fine dust generated by cutting high-density products with high-speed tools without appropriate engineering controls; and residue dust on brake drums in brake maintenance and repair shops.
Bags
Sacks or bags which have contained loose asbestos fibres, or mixtures including loose asbestos fibres, should be deposited in a suitable receptacle, under a dust extraction hood immediately after being emptied. When possible, the bags should be shredded and recycled in the process.
Process Water, Effluent Discharge
In most countries, water is an expensive commodity. Even more expensive is the discharge of used water where stringent legislation is in force. In general, effluent must undergo a series of successive treatment processes to ensure that the discharged water will cause no harm of any kind. Discharge conditions may vary by industry. Nonetheless, it is worthwhile, for legal and economical reasons, to try to reduce effluent discharge to an absolute minimum.
8.2 - TRANSPORT OF ASBESTOS WASTE
8.3 - DISPOSAL OF ASBESTOS WASTE
For friable asbestos waste, more stringent requirements apply. However, it is important to understand that waste disposal requirements for friable asbestos waste are much different than those which apply to almost all other hazardous materials.
U.S. Requirements
The sole risk of concern with friable asbestos-containing waste is that fibres may become airborne before the material is appropriately buried. As the United States Environmental Protection Agency (EPA) recently wrote: "Asbestos is not generally thought to be a threat to ground-water quality". On the other hand, for most wastes containing toxic materials, significant concerns exist about the potential for the toxic constituents - even when buried - to migrate to water and pose risk when ingested. For this reason, in the United States, asbestos disposal requirements are regulated under the Clean Air Act, while most other toxic materials are covered under the Resource Conservation and Recovery Act (RCRA).
ILO Guidelines
The ILO Code of Practice "Safety in the Use of Asbestos" also provides general guidelines for asbestos waste disposal.
General Advice
If there are no landfills specifically approved for friable asbestos waste in your country the best alternative is to use an industrial waste disposal site with a specific approval for asbestos containing waste. In case such should be neither available nor feasible, use a sanitary waste fill that meets the conditions required for disposal of asbestos-containing waste and look for an official approval.
Personal Protection and Hygiene
Workers occupied in the collection, transport or disposal of asbestos waste who may be at risk of exposure to airborne asbestos should be provided with suitable protective clothing and respiratory equipment.
Supervision
Where a company disposes of its own asbestos waste, written instructions should be issued to the workers concerned. Periodic supervision should be undertaken to ensure that the necessary safety precautions are being followed.
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