Citation and Commencement

This Technical Memorandum is issued pursuant to section 9 of the Noise Control Ordinance and may be cited as the Technical Memorandum on Noise from Percussive Piling. This Technical Memorandum shall replace the existing one that was originally published under section 11(1) of the Noise Control Ordinance in Special Supplement No.5 to Gazette Extraordinary No.38 Vol. CXXX on 7 November 1988 and came into operation on 7 December 1988. This Technical Memorandum shall come into operation in accordance with section 12 of the Noise Control Ordinance.

Application and Scope

This Technical Memorandum details the procedures that should generally be adopted by the Authority:

for determining (on the basis of the calculated noise level) any permitted hours of operation for percussive piling;

for the issuing of Construction Noise Permits for percussive piling pursuant to section 8 of the Ordinance; and

for determining whether or not any Construction Noise Permit for percussive piling is being complied with.

Interpretation

In this Technical Memorandum, unless the context otherwise requires, the following definitions apply:

"Authority" has the same meaning as in the Ordinance;

"Construction Noise Permit" has the same meaning as in the Ordinance;

"diesel hammer" means a device which imparts a percussive force to a pile by means of the downward motion of a ram which causes the compression and ignition of a charge of diesel fuel;

"double acting" describes the working principle of a piling hammer in which a percussive force is imparted to a pile by means of the direct or indirect impact of a ram or piston falling under the force of gravity with an additional downward force being exerted by a fluid at high pressure, the ram or piston being raised by means of a force imparted by a fluid at high pressure;

"drop hammer" means a device which imparts a percussive force to a pile by means of the direct or indirect impact of a mass falling under the force of gravity alone, the mass being raised by means of a crane or winch;

"hydraulic hammer" means a device which imparts a percussive force to a pile by means of the downward motion of a ram or piston which follows the single or double acting principle and is powered by hydraulic fluid at high pressure;

"internal drop hammer" means a drop hammer used in such a manner that the point of impact is at or near the bottom of the pile casing, the casing being a hollow steel tube within which the action of the hammer takes place;

"Ordinance" means the Noise Control Ordinance;

"percussive piling" has the same meaning as in the Ordinance;

"pile" has the same meaning as in the Ordinance;

"piling" has the same meaning as in the Ordinance;

"piling zone" means an area within which percussive piling may take place, as specified in a Construction Noise Permit;

"pneumatic or steam hammer" means a device which imparts a percussive force to a pile by means of the downward motion of a ram or piston which follows the single or double acting principle and is powered by air or steam at high pressure;

"Secretary" has the same meaning as in the Ordinance; and

"single acting" describes the working principle of a piling hammer in which a percussive force is imparted to a pile by means of the direct or indirect impact of a ram or piston falling under the force of gravity alone, the ram or piston being raised by means of a force imparted by a fluid at high pressure.

Standard acoustical terminology is used throughout this Technical Memorandum. Other terms are as defined in the Ordinance or in the text of this Technical Memorandum.