The Author is the Managing Director of DEMEX Consulting Engineers in Copenhagen, Denmark.
Today the demolition industry spends a lot of effort and money on environmental protection due to international standards, European directives and national laws on environmental management, for instance the ISO 14000-series, the EMAS directive, and the British Standard BS 7750 "Specification for Environmental Management Systems".
A major part of any demolition contract must be concentrated on the control of the different types of pollution.
In this presentation, I would like to offer an overall view on the pollution problems that the demolition contractor has to take into consideration during the demolition work and how to solve or control these problems.
According to the British Standard BS 7750 pollution or environmental effects can be listed as follows:
With regard to emissions to the atmosphere, we usually consider SO2, NOx and CO2 in relation to the global pollution of the atmosphere. It is appreciated that this is not a major problem to the demolition contractor. However, he can contribute to the control of air pollution by attempting to limit polluting exhaust from his machines and trucks as much as possible. In many EU countries special regulations are given to the exhaust of vehicles and machines.
Some years ago it was common that the demolition contractor burned wood and other inflammable materials on site. Owing to strict control of incineration, many countries have today banned open incineration on demolition sites. Besides the pollution of the smoke and dust from open fires, it should be underlined that much wood and inflammable materials contain a lot of hazardous chemical substances from paint, waterproofing and other covering substances, these being harmful to the atmosphere.
In many EU countries the stock of underground drinking water is very scarce. Therefore, the public authorities are very concerned about the risk of pollution of groundwater caused by industry and construction work.
Demolition work might pollute the groundwater because of the following reasons:
Generally, pollution of open water and drinking water wells can be avoided by appropriate performance of the demolition work and handling of C&D waste. However, it is important that the building owner specifies his requirements and supplies to the demolition contractor with the necessary information on sensitive water sources etc.
Generally, C&D waste is considered to be completely harmless waste material. However, within the last few years it has been realised that C&D waste contains numerous different materials, of which a number are very harmful to the environment. Several countries, e.g. USA, England, Denmark, Germany and the Netherlands are now very attentive to the fact that mixed C&D waste may cause pollution of the groundwater from leaching.
In the Netherlands, the Building Materials Decree, which became effective on 1 July 1998, sets regulations under which building materials may be applied in or on the soil or in the surface water in a safe and justified manner.
Besides discharging to water, the tipping of C&D waste at unapproved landfills or randomly chosen sites causes contamination, which may prevent future use of the land. In the case of C&D waste containing reinforced concrete elements it should be realised that the C&D waste will not disappear, but will remain forever.
According to the EU waste directives, all materials generated from construction or demolition work must be considered as waste, regardless of the possibilities of reuse or recycling. The main part of C&D waste normally consists of concrete and bricks. In Europe we estimate that 80-90% of all C&D waste is of the brick/concrete fraction, which is recyclable and may be used as a substitute for natural stone and gravel resources.
The remaining fractions contain mainly wood, timber, metals, insulation materials etc., which have to be treated in accordance with local authority regulations. In most demolition jobs some asbestos is found. However, all members of the EDA are very familiar with the technology for the investigation and removal of asbestos. The problem of lead paint has also been described in an EDA report written in 1984. In the last few years new hazardous materials have been found in buildings, such as PCB in joint filling material, insulation materials and different types of fungi. Some of the fungi need special treatment, owing to risk to humans. In recent years several public buildings in Denmark, e.g. schools, had to be demolished owing to attack by a mould-type fungus, resulting from insufficient maintenance, heating and ventilation. The contaminated parts of the buildings are treated similarly to asbestos-contaminated materials. I guess that this problem has also been discovered in other member countries.
Another special problem is the large number of chemical industries that have not been aware of the risk of polluting bricks with oil and chemicals. Effective methods of separating the uncontaminated concrete and bricks from the contaminated concrete and bricks have not yet been developed. Therefore, the treatment of this type of waste material is a problem in most countries.
According to the "the polluter pays" principle mentioned in the EC Council Directive of 18 March 1991 75/442/EEC on waste, the building owner has the overall responsibility for the correct treatment of all kinds of waste, including hazardous waste materials. The demolition contractor is responsible for complying with the rules and regulations, job description and the building owner's instructions. Normally the demolition contractor makes reservations concerning hidden and/or unexpected hazardous wastes.
In general demolition work is noisy. With respect to workers' health and safety, threshold values of noise of 85-95 dB(A) are typically given in European countries. With respect to noise emission to neighbours, certain limits are given, e.g. in the municipality of Copenhagen:
| hours from 0700 to 1800: | 70 dB(A) (equivalent value) | |
| hours from 1800 to 0700: | 40 dB(A) (equivalent value) | |
| hours from 2200 to 0700: | 55 dB(A) (maximum value) |
The possibilities of reducing the noise from a demolition site are rather limited. However, it is important that the demolition contractor plans his work and chooses his machinery in such a way that he complies with the given noise limits - otherwise he will be stopped by the Health & Safety inspectors. With reference to the requirements of environmental management, e.g. those given in BS 5570, the demolition contractor might be enforced to prepare a noise-control plan with an estimate of his noise emission and methods of control and documentation.
In the EDA publication "Health and Safety in the Demolition and Dismantling Industry", a list of noise emissions at the source from typical demolition tools and machinery is given, which can form the basis for the estimated noise emission from a demolition site.
It is known that work with vibration/chopping tools with a vibration effect of more than 120 dB (hand-arm), especially the handheld jack hammer might cause "white finger" disease. Therefore vibration-damped tools must be used and the number of hours that a worker uses them must be limited. In Denmark the Health & Safety authorities recommend that hand-held hammers are used by individuals for no more than half an hour per day.
Inconvenience to neighbours is registered in KB-levels according to the German standard DIN 4150 Teil 2. In Denmark the maximum value must not exceed 75 dB(KB).
With respect to the risk of damage to neighbouring buildings and structures, the German standard DIN 4150 gives the following threshold values for vibration velocity (mm/s):
| Industrial buildings: | 20 mm/s | |
| Dwellings: | 10 mm/s | |
| Sensitive buildings: | 3 mm/s |
These figures are used in several European countries, including Germany, the Netherlands and Denmark. A special problem, however, is the risk of damage to computers. Experience has shown that computers will not normally be affected by vibrations with acceleration below 2.5 m/s².
During demolition work, especially interior demolition work and concrete demolition, high concentrations of dust are expected. Unless special precautions are taken dust can harm the respiratory tract and lead to chronic diseases, e.g. silicosis, which is caused by dust with a high content of quartz. According to the DK threshold values for substances and materials the following threshold values are given:
| Mineral inert dust (total): | 10 mg/m³ |
| Mineral inert dust (respirable dust): | 5 mg/m³ |
| Quartz dust: | 0.1 mg/m³ |
Considering dust emissions inconvenient to neighbours, no specific threshold values are given. Normally, we say that visible dust is not acceptable as a practical limit. It is necessary that the demolition contractor ensures that the dust emission is controlled and reduced as much as possible, for instance by the use of water sprinkling and performing the dusty operations when the wind direction is appropriate.
Normally demolition work does not create obnoxious smells. However, the demolition contractor must always be careful and ensure that problems due to odours do not arise.
In former times demolition work was characterised as a very polluting work. Today many of the pollution activities might be controlled. The modern demolition contractor has no interest in the polluting image - he aspires to the green image.
Referring to the EC report, C&D Waste Project, many actions and recommendations related to the pollution from demolition work and the quality assurance of demolition work are given. It is recommended that European standards and codes of practice of demolition should be prepared within the frame of CEN/CENELEC.
In order to raise the reputation of European demolition contractors, it is necessary that the individual EDA member country prepares its own codes of good practice and environmental management systems. The philosophy of quality assurance according to the ISO 9000-series and environmental management according to BS 7750 is basically that the individual demolition contractor governs his work himself. He is not waiting for control by the authorities or others. He prepares documentation to comply with the specification of the contract, and he controls his emissions and provides the client with documentation for the emissions that are acceptable. In principle we are talking about certification of the demolition work.
Some EDA member countries have already made arrangements of certification or similar. For instance, the Danish Demolition Association entered an appointment with the Danish Minister for the Environment and Energy in November 1996 on environmental control, following a set of specified procedures and control schemes. I know that BABEX in the Netherlands has prepared National Assessment Guidelines and Britain has long had a Code of Practice for Demolition, which was revised a few years ago.
Owing to the many individual national conditions in the EDA member countries it might be too early to start work on an EDA Code of Practice for Demolition. However, I recommend that we start thinking about the content of such a standard.
I would like to conclude my presentation with the suggestion that we should consider the control of pollution and emissions as a very suitable issue for a European Demolition Standard.
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