More problems with drilling concrete

HandS problems arising for contractors as a result in CDM Regs changes - drilling in concrete.

Though UK construction employs around 7% of the country's workforce, it still accounts for 16% of major accidents and 25% of workplace fatalities.

In attempting to improve awareness of health, safety and welfare, the revised Construction Design and Management (CDM) Regulations came into force on 1st April.

It replaces the 1994 Regulations and is supported by an Approved Code of Practice (ACoP).

Given the attendant risk of exposure to vibration, noise and dust, everyday working practices such as use of power tools have taken on greater relevance.

So far, statutory requirements to minimise exposure have been achieved largely through restriction of use and development of tools which produce lower levels of vibration.

The changes set down more clearly what is expected of duty holders, with greater focus on planning and management.

This should strengthen co-ordination and co-operation between designers and contractors and simplify the way duty-holders assess competence.

The aim is to minimise risk through both the design and management of projects.

The contractor's duties remain broadly similar but more emphasis is placed on safety management.

In particular, site set-up and welfare must be in place from the beginning of the construction phase and remain in place until works end.

Principal contractors and clients now have more specific and detailed duties; it is the client's responsibility, for example, to ensure that work can be carried out without risk to health or safety.

Foremost among aspects affecting contractors is the need to 'plan, manage and monitor construction work in a way which ensures that, so far as is reasonably practicable, it is carried out without risk to health and safety'.

For a typical practice on site - drilling and fixing into concrete, health and safety legislation and guidance affecting the contractor's approach to such fixings have been introduced since 1994 CDM regulations.

Nonetheless, the two alternatives for fixing remain the same - drill and install fixing anchors or specify concrete with cast-in channels.

Through elimination of the need to drill, the cast-in channel option carries no problems associated with noise, dust or vibration.

By contrast, use of a hammer drill for more than half an hour each day requires the employer to assess and counteract risks emanating from such exposure.

For those drill users where a health risk is identified, regular surveillance must be carried out and information, instruction and training provided.

For workers regularly at risk, the Control of Vibration at Work Regulations 2005 not only limited vibration exposure but made mandatory a health surveillance programme conducted by a qualified medical practitioner or an occupational health nurse under direction.

In these cases, health records must be maintained and retained for as long as employees are under surveillance.

For protection against crystalline silica dust produced by drilling into concrete, COSHH Regulations also set a Maximum Exposure Limit (MEL) for respirable crystalline silica of 0.3 mg/m3.

The HSE's Chemical Hazard Alert Notice 35 took this a stage further by stating that ".

".

"".

"there is a much higher risk of lung damage than had been previously thought".

It advises control of exposures to a maximum 0.1 mg/m3 (8-hour TWA).

Increasing use of cast-in channel, much of it now in longer lengths, indicates that specifiers are 'gridding out' areas where multiple fixings are required to secure, for example, M and E services.

Pre-planning is of course necessary to determine where fixings are required, but it invariably benefits overall construction time.

For 'The Shires', a design and build development in Leicester by Sir Robert McAlpine, channels cast into the slab have provided fixings for the support of curtain walling.

Steve Nicolaou of structural engineers the Waterman Group commented "We prefer cast-in channels for fixing as there is no need to drill and, therefore, no risk of cutting reinforcements".

"It also meets the edge distance requirements for post fixing, which can be difficult to do with thin slabs".

From the number of T-head bolts sold to make the required fixings, a direct correlation can be made with elimination of drilling.

Among cast-in channel manufacturers, Halfen supplied over half-a-million bolts in 2006, for applications ranging from heavy-duty fixings for cladding and curtain walling support to much lighter weight bolts for M and E services support.

The updated Regulations require significant and permanent changes in duty holder attitudes and behaviour.

They offer an opportunity for a step change in health and safety performance by re-emphasising the benefits of a well managed and co-ordinated approach to the management of health and safety in construction.

Use of cast-in channels offers designers and contractors a way of limiting health risks associated with drilling while providing scope for fixing adjustment.

Practicality and welfare for once are set to combine without detriment to cost or completion times.

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