TNAG-1613-FCO40-2221-Executive-Council-of-Hong-Kong-memoranda-and-minutes-of-meet-1987 — Page 224

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2.3 Step 3

The

Determination of the Basic Noise Level (BNI)

appropriate BNL, in dB(A), for a given NSR may be

determined from Table 2, having regard to the appropriate ASR and the

time period as specified in the Construction Noise Permit application.

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2.4 Step 4 Correction for the

Permit (CNP)

Duration of the Construction Noise

If the duration of an initial CNP, or, in the case of a renewal

of a CNP, the combined duration of the initial CNP and any renewal or

renewals of a CNP for associated work on the same construction site, will

be less than or equal to 14 days, a positive correction of 3 dB(A) shall

be applied to the BNL.

A CNP shall be considered to be a renewal of a CNP if its date

of commencement is less than or equal to 21 days after the expiry date of

any other CNP for associated works on the same construction site.

2.5 Step 5

Correction for Multiple Site Situations

If in the opinion of the Authority the NSR will be materially

affected by noise from work associated with more than one CNP, the

Authority may make such correction to the BNL as it considers appropriate

having regard to standard acoustical principles and practices.

2.6 Step 6 - Determination of the Acceptable Noise Level (ANL)

The corrections obtained in Steps 4 and 5 shall be applied to

the BNL obtained in Step 3 to give the ANL.

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2.7 Step 7 Location of Items of Powered Mechanical Equipment (PME)

All items of PME should be considered to be grouped at a

position mid-way between the approximate geographical centre of the

construction site and its boundary nearest to the NSR. This position is

referred to as the notional source position.

If the construction site is irregular in shape the geographical

centre may fall outside the physical limits of the site. In such cass

the notional source position shall be taken to be the position on the

construction site boundary nearest to the geographical centre of the

site. If two such points exists, the point nearest to the NSR shall be

used.