3                           Noise

3.1                     Introduction

3.1.1.1            The assessment has concluded that impacts during the construction phase will occur as a result of the implementation of the project and, therefore, mitigation measures are required.  As such, it is recommended that construction phase environmental monitoring and audit (EM&A) is undertaken to ensure that adverse impacts do not occur. 

3.2                     EM&A Monitoring

3.2.1.1            Assessments for construction air-borne noise, ground-borne noise, operation traffic noise and operation fixed plant noise have been completed.  The assessment results show that the Trunk Road T2 project would not cause significant impacts to the nearby NSRs with proper implementation of mitigation measures and adverse residual impacts would not be expected.  For traffic noise impact, the future NSRs identified have been confirmed as being noise insulated and will, therefore, not rely on openable windows for ventilation and hence, no direct mitigation measures are required.

3.2.1.2            In terms of EM&A Monitoring requirement, it is concluded that only Construction Air-borne Noise and Operational Fixed Plant Noise would require monitoring.

3.3                     Noise Sensitive Receivers

3.3.1.1            According to the EIA report of the Trunk Road T2 project, the designated locations for the construction noise monitoring are listed in Table 3.1 and shown in Figure 3.1.

Table 3.1   Relevant Noise Sensitive Receivers

NSR No.

Noise Sensitive Receivers (NSRs)

KTD 1

Centre of Excellence in Paediatric

KTD 2

G/IC Zone next to Kwun Tong Bypass (Future Hospital at Site 3C1)

KER 1

Future Development at Kerry Godown

CKL 1

Flat 121 Cha Kwo Ling Village

CKL 2

Flat 103 Cha Kwo Ling Village

3.3.1.2            It should be noted that the identified noise sensitive receivers (NSRs) may not be occupied at the time construction commences, hence the status and location of the 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:

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

·               The monitoring close to the NSRs as defined in the EIAO-TM; and

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

3.3.1.3            If the identified NSRs are not occupied when the construction works commences, 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.

3.4                     Mitigation Measures

3.4.1.1            The recommended mitigation measures for construction noise impacts are presented the EMIS in Appendix A of this EM&A Manual.  In the event of complaints or non-compliances, the ET, Engineer and Contractor should review the effectiveness of these mitigation measures, design alternatives or additional mitigation measures as appropriate.  The Contractor should propose the corrective action to the Engineer for approval, and implement them accordingly.

3.5                     EM&A Requirements

3.5.1                 Air-Borne Noise Monitoring Requirements

Noise Parameters and Criteria

3.5.1.1            The 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.  A sample data record sheet is shown in Appendix C for reference.

Monitoring Equipment and Methodology

3.5.1.2            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.

3.5.1.3            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.

3.5.1.4            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.

3.5.2                 Construction Air-borne Noise

3.5.2.1            The designated locations for the construction noise monitoring are listed in Table 3.1 above and shown in Figure 3.1.  It should be noted that identified NSRs at the South Apron are future NSRs and may not be occupied at the time the construction of Trunk Road T2 commences.  Assessment is only required when the NSRs are occupied and in operation.

Baseline Monitoring

3.5.2.2            The ET should carry out the baseline noise monitoring prior to the commencement of the 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 the 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.

3.5.2.3            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.

3.5.2.4            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.

Impact Monitoring

3.5.2.5            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.

3.5.2.6            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.

Event and Action Plan

3.5.2.7            The Action and Limit levels for the construction noise are shown in Table 3.2.  Should non-compliances of the noise criteria occur, the action in accordance with the Event and Action Plan in Table 3.3 should be taken.

Table 3.2   Action and Limit (A/L) Levels for Construction Noise Impact Monitoring

Time Period

Action Level

Limit Level

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

 

3.5.2.8            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.

3.5.2.9            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 ER for approval, and implement the mitigation measures.

3.5.3                 Operation Fixed Plant Noise

3.5.3.1            Prior to the operation of the Trunk Road T2 project, the Contractor should conduct noise commissioning tests for all major fixed noise sources to ensure the noise emission at the louvers comply with the EIA report assessed scenario.  The ETL should agree with the IEC and EPD on the commissioning test procedures to be adopted for the commissioning test, and obtain the actual noise emissions from the fixed plant at the louvers to ensure the fixed plant noise impact at the identified NSRs would not exceed the EIA assessed scenario.  The test should be carried out by a qualified person possessing at least 7 years of noise control experience.  The noise commissioning test report should be submitted to the ER, ET and IEC for agreement.

3.5.3.2            One set of 30-minute measurement at each monitoring station should be conducted during the daytime and evening period (0700-2300 hours), and night-time (2300-0700 hours).  The Leq(30min) should be used as the monitoring parameter.  The supplementary information for the data auditing, statistical results, such as Lmax, L10 and L90 should also be obtained for reference.

Table 3.3   Event and Action Plan for Construction Noise Monitoring

EVENT

ACTION

ET(1)

IEC(1)

ER(1)

Contractor

Action Level

1.    Notify the IEC, ER and Contractor.

2.    Carry out investigation.

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

4.    Discuss jointly with the ER and Contractor and formulate remedial measures.

5.    Increase the monitoring frequency to check the mitigation effectiveness.

1.    Review the monitoring data submitted by the ET.

2.    Review the construction methods and proposed redial measures by the Contractor, and advise the ET and ER if the proposed remedial measures would be sufficient.

 

1.    Notify the Contractor.

2.    Require the Contractor to propose remedial measures for implementation if required.

1.    Submit noise mitigation proposals to the ER and copy to the IEC and ET.

2.    Implement noise mitigation proposals. 

Limit Level

1.    Notify the IEC, ER and Contractor.

2.    Identify sources.

3.    Repeat measurements to confirm findings.

4.    Carry out analysis of the Contractor’s working procedures with the ER and Contractor to determine possible mitigations to be implemented.

5.    Record the causes and action taken for the exceedances.

6.    Increase the monitoring frequency.

7.    Assess the effectiveness of the Contractor’s remedial action with the ER and keep the IEC informed of the results.

8.    If exceedance stops, cease additional monitoring.

1.    Discuss amongst the ER, ET and Contractor on the potential remedial action.

2.    Review the Contractor’s remedial action whenever necessary to assure their effectiveness and advise the ER accordingly.

3.    Supervise the implementation of remedial measures.

1.    Confirm receipt of notification of exceedance in writing.

2.    Notify the Contractor.

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

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 ER and copy to the ET and 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 ER until the exceedance is abated.

Note (1):  ET – Environmental Team, IEC – Independent Environmental Checker, ER – Engineer’s Representative

3.5.4                 Site Inspections

3.5.4.1            Inspections of the construction activities and works sites and works areas should be conducted by the Contractor at least on a weekly basis to ensure the mitigation measures to be properly implemented.

3.5.4.2            Site audits should be carried out by the Engineer, ET and Contractor, and should be based on the mitigation measures for the noise mitigation measures as recommended in Appendix A of this EM&A Manual. In the event that the recommended mitigation measures are not fully or properly implemented, the Contractor should report the deficiency to the Engineer and ET.  The following appropriate action will need to be taken by the Contractor:

·               Investigate the problems and causes;

·               Discuss a remedial and corrective proposal with the ER and ET;

·               Take action according to the action notes agreed with the ER;

·               Implement the remedial and corrective action immediately;

·               Re-inspect the site conditions upon the completion of the remedial and corrective action; and

·               Record the event.