The timber used in construction can be contaminated with various substances, therefore prior to removal, potential contaminants should always be identified in order to manage such timber most appropriately.
There is a great diversity of contaminants that can be found throughout Europe owing to different regulations as well as different treatment methods applied to wood (from which dangerous substances are derived). Some regions have good regulations regarding contaminated wood from demolition and renovation, while other regions have not yet taken steps to regulate this issue.
Hence, here we provide some very general recommendations on how to manage contaminated (or potentially contaminated) wood.
1.1. How to identify contaminated wood
To identify contaminated wood with hazardous substances, in many cases, it is enough to determine what type of wood it is, in which element it has been used and the year of manufacture. With this information, a person specialised in handling this type of material can determine directly, without the need to carry out any test that we are dealing with wood contaminated with hazardous substances.
However, this requires a thorough knowledge of the historical background of wood treatment legislation as well as the practices in the timber production market.
Even so, it is often impossible to determine, beforehand, whether wood can be considered dangerous or not.
In those situations where it is not clear if the timber falls is hazardous or not it will be necessary to carry out independent testing at an accredited laboratory, with experience in testing waste wood, to confirm whether the timber is below the threshold levels to be classified as non-hazardous or not.
Therefore, representative samples are required for classification and determining if the waste wood has hazardous properties. To take these samples correctly the following recommendations should be considered:
| RECOMMENDATIONS TO TAKE REPRESENTATIVE SAMPLES OF WOOD TO TEST | |
| 1 | Samples taken must be from a complete cross-section of the wood as treatment concentrations vary considerably from the surface to the centre. |
| 2 | Samples should be of sufficient size to ensure enough material can be prepared by the laboratory for testing, so it must be checked with the laboratory for the minimum size required. |
| 3 | It is necessary to follow the advice of the laboratory to ensure that the samples meet legal requirements when transporting them to the laboratory. |
Once the different representative samples, each sample will need to be tested, at least for substances included in the table below:
| HAZARDOUS SUBSTANCES WOOD SAMPLES NEED TO BE TESTED FOR | |
| 1 | Total metals suite, which must include Arsenic (As), Copper (Cu), Chromium (Cr), Zinc (Zn), Lead (Pb), Tin (Sn) and Antimony (Sb) |
| 2 | Where Tin (Sn) is confirmed from the total analysis as above 25mg/kg, it should be considered to be in the form of Tributyltin, and therefore tested for Tributyltin Oxide or Tributyltin Naphthenate |
| 3 | Creosote |
| 4 | Dieldrin |
| 5 | Lindane |
| 6 | Permethrin |
| 7 | Pentachlorophenol (PCP) |
| 8 | Chromated Copper Arsenate (CCA) |
Where contamination from other hazardous substances is suspected (contamination from oils and/or other chemicals, etc.) it will be necessary to discuss additional testing requirements separately with the chosen laboratory, as these will be dependent on the contamination suspected.
2.2. What to do with contaminated wood waste
Contaminated or hazardous wood must be disposed of by a licensed processor. If not properly disposed of, this wood can end up in regular landfills where chemicals can leach into the soil and damage the environment.
Furthermore, in many regions failure to dispose of waste wood correctly can result in large fines.
Depending on the hazardous substances contaminating the wood, some plants can burn hazardous waste wood to generate electricity.
2.3. What safety measures should be carried out when handling contaminated wood wastes?
When removing timber containing hazardous substances it is essential to take a series of safety precautions to ensure that workers’ health is not endangered. This is especially important when performing cuts in the wood, which will generate sawdust that can be inhaled, causing harm to health.
| SAFETY MEASURES TO AVOID RISK IN THE REMOVAL OF CONTAMINATED WOOD | |
| 1 | Ensure all the workers are provided with the correct personal protective equipment:
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| 2 | Work outside if possible, to minimize the risks of inhaling sawdust and wear goggles to prevent it from going into your eyes. |
| 3 | Clean up treated timber sawdust as you go. Either damp it down or use a vacuum fitted with a high-efficiency particulate air (HEPA) filter to clean it up. |
| 4 | If you are working inside, it is necessary to use dust extraction devices if available. Hoods and hoses fitted to saws, drilling rigs and other tools use air under negative pressure to suck sawdust away. If on the jobsite there is a lot of hazardous wood, make sure that the dust extraction device or vacuum cleaner is fitted with a HEPA filter. HEPA filters capture particles down to 1 micron in size. Dust sucked through vacuum cleaners without a HEPA filter can come out the other end of the machine and be blown back into the environment. |
| 5 | Cover any recent cuts or abrasions to avoid exposure to treated timber or treated timber sawdust. |
| 6 | Every day, the sawdust debris should be misted with water, swept up and placed in plastic bags. Then all surfaces should be wet-dusted and wet-mopped. |
| 7 | A final clean-up of the sawdust must be done. For this, a HEPA-equipped vacuum should be used on all surfaces (floors, walls, ceilings, woodwork, carpeting, furniture). Then wet-mop hardwood surfaces with a solution containing a heavy-duty household cleaner. |