Unfortunately, percussive piling necessary

I REFER to the letter Mr Ward M. Sellars headlined, ''Outlaw percussive piling'' which appeared in the South China Morning Post, on March 31.

Because of the nature characteristics and perception of noise, noise from various sources needs to be controlled by different strategies. That is how the Noise Control Ordinance is structured.

Noise Abatement Notices are used for the control of noise from stationary sources such as industrial/commercial premises and entertainments venues. Construction noise permit and noise emission labels are used to control noise from construction activities. General construction work using powered mechanical equipment between 7pm to 7am and all day during the holidays (restricted hours) require a permit that restricts the use of a number and type of equipment in order to reduce disturbance.

The exception is for emergency works where the contractors should use the quietest available equipment.

Percussive piling is very noisy in nature, but because of geological and practical engineering constraints associated with high-rise development, the use of percussive piling is unfortunately, necessary. Hence the strategy of control is to restrict the time of disturbance. Percussive piling operations can be restricted by permits from 12 hours to five or three hours depending on the degree of disturbance on nearby noise sensitive receivers.

The time restriction is to provide relief to the majority of people nearby so that noise sensitive activities can be carried on during core working hours of the day. It provides also an incentive for the contractors to use quieter methods to gain more working hours. We are aware that some contractors have already purchased quieter percussive piling equipment and have adopted non-percussive piling methods whenever they can be used.