3 nOISE

3.1 Background

3.1.1.1 The EIA study of this Project has concluded that, even with the use of all practical mitigation measures, certain residual impact would still be anticipated at some of the Noise Sensitive Receivers (NSRs) during the construction phase after implementation of all practical mitigation measures and as such, construction phase monitoring and audit is recommended. However, in the operation phase, adverse impacts would not be anticipated and noise monitoring during the operation phase of this Project is not considered necessary.

3.2 Noise Sensitive Receivers

3.2.1.1 Noise Sensitive Receivers (NSRs) have been identified in accordance with Annex 13 of the EIAO-TM which can included domestic premises, temporary housing accommodation, educational institutions, nurseries, hospitals, medical clinics, homes for the aged, convalescent homes, places of public worship, libraries, courts of law, performing arts centres, auditoria, amphitheatres, hostels and country parks. Noise sensitive receivers present within the 300m study area boundary have been identified.

3.2.1.2 The construction site is located to the northern side of the Po Lin Monastery, northwest of the Po Lin Monastery near Lin Ping Drive and to the north of the Ngong Ping 360 Terminal and Columbarium. The existing NSRs selected as representative for the construction noise assessment are listed in Table 3.1 below and illustrated in Figure 3.1.

Table 3.1 Representative Noise Sensitive Receivers

NSR ⁽¹⁾	Location	Type	No. of Storeys	Minimum Source-Receiver Slant Distance (m)*
NSR1	Columbarium of Po Lin Monastery	Place of public worship	1	18.7
NSR3	Village House No. 68	Residential	2	40.8
NSR4	Village House No. 65	Residential	2	30.8
NSR5	Village House No. 49A	Residential	1	6.5
NSR6⁽²⁾	Village House No. 40	Residential	2	24.5
NSR7	Luen Sin Tong	Place of public worship	2	35.5
NSR8	Village House No. 34	Residential	2	26.3
NSR9	Village House	Residential	2	25.7
NSR11⁽³⁾	Po Lin Monastery	Place of public worship	1	35.9

Notes: * Slant distance is the distance from the SR to the location of the PMEs in the nearest works area. Refer to Appendix C2 for the locations of the notional sources.

(1) The numbering of the NSRs is consistent with that of the ASRs in Section 3 of this EIA Report. SR2 is a shopping centre and, therefore, does not constitute an NSR for this assessment and as such, no NSR2 is included.

(2) NSR6 is an abandoned village house but is the closest property to the proposed construction works among the cluster of village houses in this area. It also offers shielding to 3 village houses behind it. It has, therefore, been selected to represent the NSRs in this area as a worst case as it would be the worst affected location.

(3) NSR11 is the kitchen house of Po Lin Monastery and would normally not be considered as an NSR. However, it is selected to represent the closest occupied building of the Monastery that would be the worst affected by the construction works.

3.2.1.3 The photos of the NSRs are also provided in Appendix C1 of the EIA Report.

3.3 Monitoring Requirements

3.3.1 Noise Parameters and Criteria

3.3.1.1 The construction noise level should be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq). The Leq(30min) should be used as the monitoring parameter for the time period from 0700-1900 hours on normal weekdays. The supplementary information for data auditing and statistical results, e.g. L10 and L90, should be obtained for reference. Sample data record sheet is included in Appendix B.

3.3.2 Monitoring Equipment and Methodology

3.3.2.1 As referred to the requirements of the Technical Memorandum (TM) issued under the NCO, the sound level meters in compliance with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications should be used for carrying out the noise monitoring. Immediately prior to and following each noise measurement, the accuracy of the sound level meter should be checked using an acoustic calibrator generating a known sound pressure level at a known frequency. The measurements may be accepted as valid only if the difference between calibration levels obtained before and after the noise measurement is less than 1.0 dB.

3.3.2.2 The noise measurements should not be made in the presence of fog, rain, wind with a steady speed exceeding 5m/s or wind with gusts exceeding 10m/s. The wind speed should be checked with a portable wind speed meter capable of measuring wind speeds in m/s.

3.3.2.3 The ET is responsible for the provision of the monitoring equipment and should 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 should be clearly labelled.

3.3.3 Monitoring Locations

3.3.3.1 According to the environmental findings detailed in the EIA report of the Ngong Ping drainage improvement works, the designated locations for the construction noise monitoring are listed in Table 3.2 and shown in Figures 3.2 and 3.3.

Table 3.2: Representative Noise Sensitive Receivers Identified for Construction Noise Impact Monitoring

NSRs*	Monitoring Location
NSR1	Columbarium of Po Lin Monastery
NSR5	Village House No. 49A
NSR8	Village House No. 34

* NSRs = Noise Sensitive Receivers

3.3.3.2 The status and location of the noise sensitive receivers (NSRs) may change after this EM&A Manual has been issued. In such case, and if changes to the monitoring locations are considered necessary, the ET should propose alternative monitoring locations and seek the agreement from the IEC and EPD on such proposal. When alternative monitoring locations are proposed, they should be chosen based on the following criteria:

(i) The monitoring locations close to the major construction works activities that are likely to have noise impacts;

(ii) The monitoring close to the NSRs as defined in the EIAO-TM; and

(iii) The assurance of the minimal disturbance and working under a safe condition to the occupants during the monitoring in the vicinity of the NSRs.

3.3.3.3 The monitoring stations should normally be at a point 1m from the exterior of the facade of the NSR and be at a position 1.2m above ground. If there is a problem with access to the normal monitoring position, an alternative position should be chosen, and a correction to the measurement results should be made. For reference, a correction of +3dB(A) should be made to the free-field measurements. The ETL should agree with the IEC and EPD on the alternative monitoring position and corrections adopted. Once the positions for the monitoring stations are chosen, the baseline and impact monitoring should be carried out at the same positions.

3.3.4 Baseline Monitoring

3.3.4.1 The ET should carry out the baseline noise monitoring prior to the commencement of the major construction works. The baseline noise levels should be measured for a continuous period of at least 14 consecutive days at a minimum logging interval of 30 minutes during daytime between 0700-1900. The Leq, L10 and L90 should be recorded at the specified intervals. A schedule for the baseline monitoring should be submitted to the IEC for approval before the baseline monitoring starts.

3.3.4.2 There should not be any construction activities in the vicinity of the monitoring stations during the baseline monitoring. Any non-project related construction activities in the vicinity of the monitoring stations during the baseline monitoring should be noted and the source and location of such activities should be recorded.

3.3.4.3 In exceptional cases, when baseline monitoring data obtained are insufficient or questionable, the ET should liaise with the IEC and EPD to agree on an appropriate set of data to be used as the baseline reference.

3.3.5 Impact Monitoring

3.3.5.1 The impact noise monitoring should be carried out at all the designated monitoring stations when there are project-related construction activities undertaken within a radius of 300m from the monitoring stations. Monitoring of Leq(30min) should be carried out at each station at 0700-1900 hours on normal weekdays at a frequency of once a week when construction activities are underway. Any general construction work carried out during restricted hours is controlled by Construction Noise Permit (CNP) under the NCO.

3.3.5.2 In case of non-compliances with the construction noise criteria, more frequent monitoring as specified in the Event and Action Plan should be carried out. This additional monitoring should be continued until the recorded noise levels show that the non-compliance is rectified or proved to be irrelevant to the project-related construction activities.

3.4 Event and Action Plan

3.4.1.1 The Action and Limit levels for the construction noise are shown in Table 3.3. Should non-compliances of the noise criteria occur, the action in accordance with the Event and Action Plan in Table 3.4 should be taken.

Table 3.3: Action and Limit (A/L) Levels for Construction Noise Impact Monitoring

Time Period

Action Level

Limit Level, L_{eq
30mins}, dB(A)

0700-1900 hours on normal weekdays

When one documented complaint is received

75 dB(A) for residential premises

70 dB(A) for school and

65 dB(A) during examination period

3.4.1.2 In order to account for cases in which ambient noise levels, as identified in the baseline monitoring, approach or exceed the stipulated Limit Levels prior to the commencement of the construction works, a Maximum Acceptable Impact Level, which incorporates the baseline noise levels and the identified construction noise Limit Level, may be defined and agreed with the EPD. The amended level would be greater than 75 dB(A) and represent the maximum acceptable noise level at a specific monitoring station. The correction factors for the effects of the acoustic screening and/or architectural features of the NSRs may also be applied as specified in the EIAO-TM.

Table 3.4: Event and Action Plan for Construction Noise Monitoring

EVENT	ACTION
EVENT	ET⁽¹⁾	IEC⁽¹⁾	Engineer	Contractor
Action Level	1. Notify the 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 Engineer 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 the IEC. 2. Implement noise mitigation proposals.
Limit Level	1. Notify the IEC, Engineer, EPD and Contractor. 2. Identify sources. 3. Repeat measurements to confirm findings. 4. Increase monitoring frequency. 5. Carry out analysis of the Contractor’s working procedures to determine possible mitigation to be implemented. 6. Inform the IEC, Engineer and EPD the causes and action taken for the exceedances. 7. Assess the effectiveness of the Contractor’s remedial action and keep the IEC, EPD and Engineer informed of the results. 8. If exceedance stops, cease additional monitoring.	1. Discuss amongst the Engineer, ET and Contractor on the potential remedial action. 2. Review the Contractor’s remedial action whenever necessary to assure their effectiveness and advise the Engineer 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 portion of work is responsible and instruct the Contractor to stop that portion of works until the exceedance is abated.	1. Take immediate action to avoid further exceedance. 2. Submit proposals for remedial action to the IEC within 3 working days of notification. 3. Implement the agreed proposals. 4. Resubmit proposals if problems still not under control. 5. Stop the relevant portion of works as determined by the Engineer until the exceedance is abated.

Note (1): ET – Environmental Team, IEC – Independent Environmental Checker;

3.5 Mitigation Measures

3.5.1.1 According to the EIA report, the construction activities would cause noise exceedances at various NSRs and, therefore, appropriate mitigation measures and good site practices are recommended. The Contractor should be responsible for the design and implementation of these measures. The EMIS is included in Appendix A of this EM&A Manual including:

(i) For Construction identified to be Activity 1 – Site Clearance, removal of trees would require a quieter electric powered chain with a SWL of 103dB(A) or lower saw during tree felling;

(ii) Use of quiet plant offering a 2-14dB(A) of noise reduction;

(iii) Use of a mini robot mounted excavator (CNP 082) for works at RP4 / Outfall B;

(iv) Enhancement of boundary wall for NSR 1 so that an attenuation of 10dB(A) for the NSR is achieved;

(v) Use of fixed temporary noise barrier with 3m in height at the location between NSR5 and the open cut trench (Works Section 5);

(vi) Use of fixed temporary noise barrier for specific equipment as detailed in the EIA Report;

(vii) Use of only well-maintained plant and PME should be serviced regularly during the construction programme;

(viii) Silencers or mufflers on construction equipment should be utilised and properly maintained throughout the construction programme;

(ix) Any mobile PME should be sited as far from NSRs as possible;

(x) Machines and PME that may be in intermittent use should be shut down between work periods or should be throttled down to a minimum;

(xi) PME known to emit noise strongly in one direction should be orientated to direct away from the nearby NSRs; and

(xii) Material stockpiles and other structures should be effectively utilised, wherever practicable, in screening noise from on-site construction activities.

(xiii) Use of acoustic enclosure, in accordance with EPD’s A Practical Guide for the Reduction of Noise from Construction Works;

(xiv) For areas where noise exceedances were predicted, the use of manual working (i.e. use of hand tools) should be considered, which would eliminate noise impact arising from the use of PME; and

(xv) Re-scheduling of works should be considered to ameliorate the residual impact.

3.5.1.2 In the event of exceedances or complaints, the Contractor should review the effectiveness of these mitigation measures and propose, design and implement alternative or additional measures as appropriate. The Contractor should liaise with the ET on the alternative or additional mitigation measures, provide them to the Engineer for approval, and implement the mitigation measures.