Demolition Statement
1
UNIT 10 - DEMOLITION HAZARDS AND CONTROL 132 © ACT exposure to asbestos during stripping operations especially if workers are unaware of its presence and no precautions have been taken. Asbestos fibres get into the lungs and it can take many years (sometimes up to 40 years) before the symptoms of illnesses like mesothelioma (cancer of the membrane lining the lungs) become apparent. The asbestos fibres may also be released into the air and contaminate clothing which may pose an additional risk of harm to other workers and the public in the vicinity. Asbestos may be present in lagging of boilers and pipe work, fire proofing of structures and roofing materials. It is important to obtain details of any survey conducted on the building or structure for consideration before work starts. Special arrangements are required for the removal and disposal of asbestos materials. PROXIMITY OF OTHER STRUCTURES When work is to be carried out in close proximity to roadways or other structures, steps have to be taken to minimise the risk and nuisance to adjoining land, building or road users. Notification in good time to local residents is essential. Other safety issues such as security, selection of demolition method, dust and noise are dealt with in other sections of this unit. 10.2 - Demolition method statement All demolition/dismantling work are covered by CDM. Part of the planning work for any project should include the development of method statements. These should consider all or some of the following issues where necessary. Type and sequence of demolition PIECEMEAL Piecemeal demolition is done by hand using hand held tools and is sometimes a preliminary to other methods. It can be completed or begun by machines. For example, when demolishing a tall chimney with occupied buildings in close proximity, the job may commence with the painstaking task of dismantling by hand - brick by brick. When the structure has been reduced to about 10 metres, then conventional heavy equipment can be used. CONTROLLED COLLAPSE AND PRE-WEAKENING Deliberate controlled collapse involves the pre-weakening of the structure or building. This involves removing key structural members so the remaining structure collapses under its own weight. There are several problems associated with this method of demolition: The structure may collapse to a greater extent than was anticipated. The planned collapse may only be a partial collapse and could leave the structure hazardous and insecure. The resultant debris may be projected over a wider area than anticipated. The pile of debris that is left after the collapse of the structure may be in a dangerous condition, presenting a serious risk to those who remove it. One method of removing the key structural members is overturning by wire rope pulling. Wires are attached to the main supports, which are pulled away using a heavy tracked vehicle or a winch to provide the motive power. The area must be cleared of workers for this operation and there must be enough clearance for the vehicle to move the distance required to pull out the structural supports. Problems associated with this method arise when the wire becomes overstressed. If it breaks, then whiplash can occur which can have the force to slice through the human body. The forces applied may be enough to overturn the winch or the tracked vehicle. Another problem can occur when the action of pulling has begun and there is inadequate power to complete it. Use of explosives - The use of explosives requires the expertise of an experienced explosives engineer. Also, the HSE should be consulted to ensure compliance with The Control of Explosives Regulations 1991. There are a number of factors to be considered for safe demolition with the use of explosives, which include: The local and structural conditions must be considered when fixing the size of the charges. The structure to be blasted can be divided into a number of sections and suitable charges applied to each section. Shot holes should be drilled electrically. Drilling pneumatically could cause vibration, which could result in premature collapse. Charges should not be placed near cast iron as it easily shatters into shrapnel. The area around the structure being demolished and the firing point should be barricaded and unauthorised persons not allowed to enter. The demolition engineer must be satisfied that no dangerous situation or condition has been left or created. The danger zone must be barricaded until rendered safe. Figure 10-5: Protection of public. Source: ACT. Figure 10-6: Disposal of waste. Source: ACT.
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Transcript of Demolition Statement
UNIT 10 - DEMOLITION HAZARDS AND CONTROL
132 © ACT
exposure to asbestos during stripping operations especially if workers are unaware of its presence and no precautions have been taken. Asbestos fibres get into the lungs and it can take many years (sometimes up to 40 years) before the symptoms of illnesses like mesothelioma (cancer of the membrane lining the lungs) become apparent. The asbestos fibres may also be released into the air and contaminate clothing which may pose an additional risk of harm to other workers and the public in the vicinity. Asbestos may be present in lagging of boilers and pipe work, fire proofing of structures and roofing materials. It is important to obtain details of any survey conducted on the building or structure for consideration before work starts. Special arrangements are required for the removal and disposal of asbestos materials.
PROXIMITY OF OTHER STRUCTURES When work is to be carried out in close proximity to roadways or other structures, steps have to be taken to minimise the risk and nuisance to adjoining land, building or road users. Notification in good time to local residents is essential. Other safety issues such as security, selection of demolition method, dust and noise are dealt with in other sections of this unit.
10.2 - Demolition method statement All demolition/dismantling work are covered by CDM. Part of the planning work for any project should include the development of method statements. These should consider all or some of the following issues where necessary.
Type and sequence of demolition PIECEMEAL Piecemeal demolition is done by hand using hand held tools and is sometimes a preliminary to other methods. It can be completed or begun by machines. For example, when demolishing a tall chimney with occupied buildings in close proximity, the job may commence with the painstaking task of dismantling by hand - brick by brick. When the structure has been reduced to about 10 metres, then conventional heavy equipment can be used.
CONTROLLED COLLAPSE AND PRE-WEAKENING Deliberate controlled collapse involves the pre-weakening of the structure or building. This involves removing key structural members so the remaining structure collapses under its own weight. There are several problems associated with this method of demolition:
The structure may collapse to a greater extent than was anticipated. The planned collapse may only be a partial collapse and could leave the structure hazardous and insecure. The resultant debris may be projected over a wider area than anticipated. The pile of debris that is left after the collapse of the structure may be in a dangerous condition, presenting a serious risk to
those who remove it. One method of removing the key structural members is overturning by wire rope pulling. Wires are attached to the main supports, which are pulled away using a heavy tracked vehicle or a winch to provide the motive power. The area must be cleared of workers for this operation and there must be enough clearance for the vehicle to move the distance required to pull out the structural supports. Problems associated with this method arise when the wire becomes overstressed. If it breaks, then whiplash can occur which can have the force to slice through the human body. The forces applied may be enough to overturn the winch or the tracked vehicle. Another problem can occur when the action of pulling has begun and there is inadequate power to complete it. Use of explosives - The use of explosives requires the expertise of an experienced explosives engineer. Also, the HSE should be consulted to ensure compliance with The Control of Explosives Regulations 1991. There are a number of factors to be considered for safe demolition with the use of explosives, which include:
The local and structural conditions must be considered when fixing the size of the charges. The structure to be blasted can be divided into a number of sections and suitable charges applied to each section.
Shot holes should be drilled electrically. Drilling pneumatically could cause vibration, which could result in premature collapse. Charges should not be placed near cast iron as it easily shatters into shrapnel. The area around the structure being demolished and the firing point should be barricaded and unauthorised persons not
allowed to enter. The demolition engineer must be satisfied that no dangerous situation or condition has been left or created. The danger zone
must be barricaded until rendered safe.
Figure 10-5: Protection of public. Source: ACT.
Figure 10-6: Disposal of waste. Source: ACT.
