4 NOISE

4.1 Introduction

4.1.1.1 Based upon the EIA Report, while impacts are not predicted, as the results are marginally within the criteria, EM&A is recommended at existing Noise Sensitive Receivers (NSRs) in North Lantau during the construction phase to ensure the noise levels are reduced to acceptable levels.

4.2 Noise Parameters

4.2.1.1 The construction noise level shall be monitored by the ET and shall be measured in terms of the A-weighted equivalent continuous sound pressure level (L_eq). L_eq _{(30 min)} shall be used as the monitoring parameter for the time period between 0700-1900 hours on normal weekdays. In respect of all other time periods, L_{eq(5 min)} shall be employed for comparison with the Noise Control Ordinance criteria.

4.2.1.2 As supplementary information for data auditing, statistical results such as L₁₀ and L₉₀ shall also be obtained for reference and shall be recorded by the ES. A sample data record sheet is shown in Figure 4.1 for reference.

4.3 Monitoring Equipment

4.3.1.1 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.

4.3.1.2 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 agree to within 1.0dB.

4.3.1.3 Noise measurements shall not be made in fog, rain, wind with a steady speed exceeding 5m/s or wind with gusts exceeding 10m/s. The wind speed shall be checked with a portable wind speed meter capable of measuring the wind speed in m/s.

4.3.1.4 The Contractor shall ensure that sufficient noise measuring equipment and associated instrumentation are available for carrying out the baseline monitoring, construction phase impact monitoring and ad hoc monitoring. All the equipment and associated instrumentation shall be clearly labelled.

4.4 Monitoring Locations

4.4.1.1 The representative noise monitoring stations/sensitive receivers are shown in Figure 4.2. If the status or locations of noise sensitive receivers change after issuing this manual, the ET shall propose the updated monitoring locations and seek approval from the Engineer’s Representative (ER) and agreement from the Independent Environmental Checker (IEC) and Environmental Protection Department (DEP) of the proposal to amend the monitoring locations.

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

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

b) monitoring at the noise sensitive receivers as defined in the Technical Memorandum; and

c) assurance of minimal disturbance to the occupants during monitoring.

4.4.1.3 The monitoring station shall normally be at a point 1m from the exterior of the sensitive receivers building facade and, in the case the measurement is not being carried out at a building, be at a position 1.2m above the ground. If there is problem with access to the normal monitoring position, an alternative position may be chosen and a correction to the measurements shall be made.

4.4.1.4 For reference, a correction of +3dB(A) shall be made to the free field measurements. Noise levels shall be corrected in accordance with Section 2.10, 2.11 and 2.13 of the “Technical Memorandum on Noise From Construction Works Other Than Percussive Piling”. The ET shall agree with the IEC on the monitoring position and the corrections adopted prior to the commencement of the works.

4.4.1.5 Once the positions for the monitoring stations are chosen, the baseline monitoring and the construction phase impact monitoring shall be carried out at the same positions.

4.4.1.6 The Contractor shall establish the construction equipment list and construction schedule which shall be checked and approved by the ER and agreed by the IEC. The timing of the noise impact monitoring work shall be developed by the ES based upon the construction schedule prepared by the Contractor. The monitoring programme shall be approved by the ER, the IEC and the DEP and shall be reviewed on a regular basis in light of any changes to the Contractor’s construction schedule.

4.5 Baseline Monitoring

4.5.1.1 The ET shall carry out baseline noise measurements at each monitoring stations shown in Figure 4.2 prior to the commencement of the construction work over a 24 hour period. The baseline monitoring shall be carried out daily for a period of at least two weeks and shall be undertaken no earlier than three weeks prior to construction works being carried out. In no circumstance should construction works be carried out within the range of the monitoring stations during the two weeks of baseline monitoring.

4.5.1.2 Before commencing the baseline monitoring, the ET shall submit the monitoring schedule to the ER for approval. The IEC shall also be informed of the baseline monitoring programme such that the IEC can conduct on-site audits to ensure the accuracy of the monitoring results.

4.5.1.3 Any non project related construction activities in the vicinity of the stations during the baseline monitoring shall be noted and the source and location recorded.

4.6 Construction Phase Impact Monitoring

4.6.1.1 Noise monitoring shall be carried out at each of the designated monitoring stations directly affected by the construction works once every 6 days after the commencement of construction. During construction works between 0700-1900 hours, one set of Leq_{(30 mins)} measurements on normal weekdays shall be taken. If construction works are extended to include works during the hours of 1900-0700, additional weekly impact monitoring comprising 3 consecutive L_eq(5
mins) shall be carried out during evening and nighttime works and applicable permits shall be obtained by the Contractor in accordance with the NCO.

4.6.1.2 In case of non-compliance with the construction noise criteria, more frequent monitoring as specified in the Action Plan in Table 4.2 shall be carried out. This additional monitoring shall be continued until the recorded noise levels are rectified or proved to be unrelated to the construction activities.

4.7 Event and Action Plan for Construction Noise

4.7.1.1 The Action and Limit levels for construction noise are defined in Table 4.1. Should non-compliance of the criteria occur, the ET, the IEC, the ER and the Contractor shall undertake their specified actions in accordance with the Action Plan shown in Table 4.2.

Table 4.1 Action and Limit Levels for Construction Noise

Time Period	Action	Limit
0700-1900 hrs on normal weekdays	When one documented complaint is received	75* dB(A)

* reduce to 70 dB(A) for schools and 65 dB(A) during school examination periods.

4.8 Noise Mitigation Measures

4.8.1.1 As no impacts are predicted during the construction stage at the existing NSRs in north Lantau, no specific mitigation measures have been recommended. However, the Contractor will be responsible for ensuring noise levels are minimized as far as possible through the application of good site practices, including maintenance of equipment. During the operational phase, no mitigation is required.

Table 4.2 Event / Action Plan for Construction Noise

EVENT	ACTION
EVENT	ET	IEC	ER	Contractor
Action Level	1. Notify the IEC and the Contractor. 2. Carry out investigation. 3. Report the results of investigation to the IEC and the 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 the Contractor. 3. Require the 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 the IEC, the ER, the DEP and the Contractor. 2. Identify the source. 3. Repeat measurement to confirm findings. 4. Increase monitoring frequency. 5. Carry out analysis of Contractor’s working procedures to determine possible mitigation to be implemented. 6. Inform the IEC, the ER and the DEP the causes & actions taken for the exceedances. 7. Assess effectiveness of the Contractor’s remedial actions and keep the IEC, the DEP and the ER informed of the results. 8. If exceedance stops, cease additional monitoring.	1. Discuss amongst the ER, the ET and the Contractor on the potential remedial actions. 2. Review the Contractor’s remedial actions whenever necessary to assure their effectiveness and advise the ER accordingly. 3. Supervise the implementation of remedial measures.	1. Confirm receipt of notification of failure in writing. 2. Notify the Contractor. 3. Require the Contractor to propose remedial measures for the analysed noise problem. 4. Ensure remedial measures are properly implemented. 5. If exceedance continues, consider what activity of the work is responsible and instruct the Contractor to stop that activity of work until the exceedance is abated.	1. Take immediate action to avoid further exceedance 2. Submit proposals for remedial actions to IEC within 3 working days of notification 3. Implement the agreed proposals 4. Resubmit proposals if problem still not under control 5. Stop the relevant activity of works as determined by the ER until the exceedance is abated.

Note: ET – Environmental Team, IEC – Independent Environmental Checker, ER – Engineer’s Representative

Figure 4.1 Noise Monitoring Field Record Sheet

Monitoring Location:
Description of Location:
Date of Monitoring:
Measurement Start Time (hh:mm):
Measurement Time Length (min.):
Noise Meter Model/Identification:
Calibrator Model/Identification:
Measurement Results	L₉₀ (dB(A)):
	L₁₀ (dB(A)):
	Leq (dB(A)):
Major Construction Noise Source(s) During Monitoring:
Other Noise Source(s) During Monitoring:
Remarks:

Name & Designation Signature Date

Recorded By :

Checked By :