4                    NOISE IMPACT

 

4.1      Construction Phase

 

Noise monitoring is recommended during the construction phase to ensure compliance with the noise criterion at the NSRs.  Weekly noise monitoring should be undertaken at the representative NSRs (N1 – N4) (Table 4.1 and Figure 4.1).  Regular site audits at the frequency of twice a month should be conducted to ensure that the recommended mitigation measures are properly implemented during the construction stage. 

 

In accordance with the recommendations of the EIA, mitigation measures have been proposed during the construction phase of the Project.  Details of the mitigation measures are presented in Appendix E - Implementation Schedule.

 

Table 4.1 Locations for Construction Noise Monitoring

NSR

Location

N1

Village house - No. 165A Lung Mei

N2*

Village house - No. 103 Lung Mei

N3

Village house - No. 70 Lo Tsz Tin

N4

Village house - No. 79 Lo Tsz Tin

 *Noise mitigation should be conducted at N2a (i.e House No. 101 Lung Mei) if it is changed to residential use during construction phase.

　

4.1.1   Noise Parameters

 

The construction noise level shall be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq).  Leq(30 min) shall be used as the monitoring parameter for the time period between 0700-1900 hours on normal weekdays.  For all other time periods, Leq(5 min) shall be employed for comparison with the NCO criteria.

 

As supplementary information for data auditing, statistical results such as L10 and L90 shall also be obtained for reference.  A sample data record sheet is shown in Appendix C for reference.

 

4.1.2   Monitoring Equipment

 

As referred to in the Technical Memorandum (TM) issued under the Noise Control Ordinance (NCO), sound level meters in compliance with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications shall be used for carrying out the noise monitoring.  Immediately prior to and following each noise measurement the accuracy of the sound level meter shall be checked using an acoustic calibrator generating a known sound pressure level at a known frequency. Measurements may be accepted as valid only if the calibration level from before and after the noise measurement agrees to within 1.0 dB.  Noise measurements should not be made in accordance with standard acoustical principles and practices in relation to weather conditions.

 

The ET Leader is responsible for the availability of monitoring equipment. He shall ensure that sufficient noise measuring equipment and associated instrumentation are available for carrying out the baseline monitoring, regular impact monitoring and ad hoc monitoring. All the equipment and associated instrumentation shall be clearly labelled.

 

4.1.3   Monitoring Locations

 

The noise monitoring locations have been shown in Table 4.1 and Figure 4.1. The status and locations of noise sensitive receivers may change after issuing this manual.  If such cases exist, the ET Leader shall propose updated monitoring locations and seek approval from ER and agreement from the IEC and EPD of the proposal.

 

When alternative monitoring locations are proposed, the monitoring locations shall be chosen based on the following criteria:

 

a)        at locations close to the major site activities which are likely to have noise impacts;

b)        close to the noise sensitive receivers (N.B. For the purposes of this section, any domestic premises, hotel, hostel, temporary housing accommodation, hospital, medical clinic, educational institution, place of public worship, library, court of law, performing art centre shall be considered as a noise sensitive receiver); and

c)        for monitoring locations located in the vicinity of the sensitive receivers, care shall be taken to cause minimal disturbance to the occupants during monitoring.

 

The monitoring station shall normally be at a point 1m from the exterior of the sensitive receivers building facade and be at a position 1.2m above the ground.  If there is a problem with access to the normal monitoring position, an alternative position may be chosen, and a correction to the measurements shall be made.  For reference, a correction of +3 dB(A) shall be made to the free field measurements.  The ET Leader shall agree with the IEC on the monitoring position and the corrections adopted. Once the positions for the monitoring stations are chosen, the baseline monitoring and the impact monitoring shall be carried out at the same positions.

 

4.1.4   Impact Monitoring

 

Weekly noise monitoring shall be carried out at all the designated monitoring stations to obtain one set of 30-minute measurement between 0700-1900 hours. 

 

General construction work carrying out during restricted hours is controlled by CNP system under the NCO.

 

In case of non-compliance with the construction noise criteria, more frequent monitoring as specified in the Action Plan in Table 4.3 shall be carried out.  This additional monitoring shall be continued until the recorded noise levels are rectified or proved to be irrelevant to the construction activities.

 

4.1.5   Event and Action Plan for Noise

 

The Action and Limit levels for construction noise are defined in Table 4.2. Should non-compliance of the noise quality criteria occur, actions in accordance with the Action Plan in Table 4.3 shall be carried out.

 

Table 4.2 Action and Limit Levels for Construction Noise Monitoring

Time Period

Action

Limit

0700-1900 hrs on normal weekdays

When one documented compliant is received

75* dB(A)

Table 4.3   Event and Action Plan for Noise

EVENT

ACTION

ET

IEC

ER

Contractor

Action Level

1.        Notify IEC and Contractor;

2.        Carry out investigation;

3.        Report the results of investigation to the IEC and Contractor;

4.        Discuss with the Contractor and formulate remedial measures;

5.        Increase monitoring frequency to check mitigation effectiveness 

1.     Review the analysed results submitted by the ET;

2.     Review the proposed remedial measures by the Contractor and advise the ER accordingly;

3.     Supervise the implementation of remedial measures

1.      Confirm receipt of notification of failure in writing;

2.      Notify Contractor;

3.      Require Contractor to propose remedial measures for the analysed noise problem;

4.      Ensure remedial measures are properly implemented

1.         Submit noise mitigation proposals to IEC;

2.         Implement noise mitigation proposals

Limit Level

1.        Notify IEC, ER, EPD and Contractor;

2.        Identify source;

3.        Carry out investigation;

4.        Report the results of investigation to the IEC and Contractor;

5.        Discuss with the Contractor and formulate remedial measures;

6.        Increase monitoring frequency to check mitigation effectiveness 

1.     Review the analysed results submitted by the ET;

2.     Review the proposed remedial measures by the Contractor and advise the ER accordingly;

3.     Supervise the implementation of remedial measures

1.      Confirm receipt of notification of failure in writing;

2.      Notify Contractor;

3.      Require Contractor to propose remedial measures for the analysed noise problem;

4.      Ensure remedial measures are properly implemented

1.         Submit noise mitigation proposals to IEC;

2.         Implement noise mitigation proposals
ET – Environmental Team, IEC – Independent Environment Checker, ER – Engineer Representative

 

4.2              Operation Phase

 

Results of operational noise assessment indicate that the NSRs will not be affected by fixed plant noise sources and therefore operational phase noise monitoring is not required.