3      NOISE.. 3-1

3.1         Introduction.. 3-1

3.2         Noise Parameters. 3-1

3.3         Monitoring Equipment. 3-1

3.4         Monitoring Locations. 3-2

3.5         Baseline Monitoring.. 3-2

3.6         Impact Monitoring.. 3-2

3.7         Event and Action Plan.. 3-2

3.8         Noise Mitigation Measures. 3-2

3                    NOISE

3.1              Introduction

3.1.1        In this section, the general requirements, methodology, equipment, and mitigation measures for the monitoring and audit of noise impacts associated with the construction and operation phase of the Designated Projects are described below. The specific noise EM&A requirements for each of the Designated Projects are defined in Appendices D to I.

 

3.2              Noise Parameters

 

Construction Phase

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

3.2.2        Supplementary information for data auditing, statistical results such as L10 and L90 shall also be obtained for reference.  A sample data record sheet based on the one presented in the EM&A Guidelines for Development Projects in Hong Kong is shown in Appendix B.  The ET Leader may modify the data record sheet for this EM&A programme, of which the format should be agreed by the ER and the IEC.

3.2.3        The locations of representative noise sensitive receivers within the Study Area of the Designated Projects are shown in Figure 3.1.

 

Operation Phase

3.2.4        The traffic noise level shall be measured twice within the first year of the road opening.  Measurement shall be made in terms of A-weighted L10 over three half-hour periods during the peak traffic hour.  Other metrics like Leq may be added as seen fit.  A sample data record sheet is shown in Appendix B for reference.

 

3.3              Monitoring Equipment

3.3.1        As referred to in the Technical Memorandum (TM) issued under the 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 agree to within 1.0 dB. 

3.3.2        Noise measurements shall not be made in fog, rain, wind with a steady speed exceeding 5 m s-1 or wind with gusts exceeding 10 m s-1.  The wind speed shall be checked with a portable wind speed meter capable of measuring the wind speed in m s-1.

3.3.3        The ET is responsible for the provision of the 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.

 

3.4              Monitoring Locations

3.4.1        The locations of noise monitoring stations during construction and operation phases of the Designated Projects are shown in Figures 3.2 and 3.3 respectively, while the noise monitoring stations for each of the Designated Projects are outlined in Appendices D to I of this EM&A Manual.

 

3.5              Baseline Monitoring

 

Construction Phase

3.5.1        The ET shall carry out baseline noise monitoring prior to the commencement of the construction works.  The baseline monitoring shall be carried out daily for a period of at least two weeks.  Before commencing the baseline monitoring, the ET shall develop and submit to the IEC the baseline monitoring programme such that the IEC can conduct on-site audit to ensure accuracy of the baseline monitoring results.

3.5.2        There shall not be any construction activities in the vicinity of the stations during the baseline monitoring.

3.5.3        In exceptional cases, when insufficient baseline monitoring data or questionable results are obtained, the ET Leader shall liaise with the ER, EPD and IEC to agree on an appropriate set of data to be used as a baseline reference and submit to the ER and IEC for agreement and EPD for approval.

 

Operation Phase

3.5.4        No baseline operation noise monitoring is generally required.

 

3.6              Impact Monitoring

 

Construction Phase

3.6.1        Noise monitoring shall be carried out at all the designated monitoring stations.  The monitoring frequency shall depend on the scale of the construction activities.  The following is an initial guide on the regular monitoring frequency for each station on a weekly basis when noise generating activities are underway:

(a)              one set of measurements between 0700 and 1900 hours on normal weekdays.

3.6.2        If construction works are extended to include works during the hours of 1900 – 0700 as well as public holidays and Sundays, additional weekly impact monitoring shall be carried out during respective restricted hours periods.  Applicable permits under NCO shall be obtained by the Contractor.

3.6.3        If a school exists near the construction activity, noise monitoring shall be carried out at the monitoring stations for the schools during the school examination periods.  The ET Leader shall liaise with the school’s personnel and the Examination Authority to ascertain the exact dates and times of all examination periods during the course of the contract.

3.6.4        In case of non-compliance with the construction noise criteria, more frequent monitoring, as specified in the Action Plan in Table 3.2, shall be carried out.  This additional monitoring shall be continued until the recorded noise levels are rectified or demonstrated to be unrelated to the construction activities.

 

Operation Phase

 

3.6.5        Traffic noise monitoring shall be carried out at all the designated traffic noise monitoring stations as shown in Figure 3.3.  The following is an initial guide on the traffic noise monitoring requirements during the operation phase:

(i)                one set of measurements at the morning traffic peak hour on normal weekdays;

(ii)              one set of measurement at the evening traffic peak hour on normal weekdays;

(iii)            a concurrent census of traffic flow and percentage heavy vehicles shall be conducted for the far-side and near-side of the road and the existing road network in the vicinity of each measurement points;

(iv)            average vehicle speed estimated for far-side and near-side of the road and the existing road network in the vicinity of each measuring points; and

(v)              the two sets of monitoring data shall be obtained within the first year of operation.

 

3.6.6        Measured noise levels shall be compared with the predicted noise levels by applying appropriate conversion corrections to allow for the traffic conditions at the time of measurement. 

 

3.7              Event and Action Plan

 

Construction Phase

 

3.7.1        The Action and Limit levels for construction noise are defined in Table 3.1.  Should non-compliance of the criteria occur, action in accordance with the Event and Action Plan in Table 3.2 shall be implemented.

Table 3.1         Action and Limit Levels for Construction Noise

Time Period

Action Level

Limit Level

0700 – 1900 hours

on normal weekdays

When one documented complaint is received

75 dB(A) * 

 

Notes:    If works are to be carried out during restricted hours, the conditions stipulated in the Construction Noise Permit (CNP) issued by the Noise Control Authority have to be followed.

* 70 dB(A) and 65 dB(A) for schools during normal teaching periods and school examination periods, respectively.

 

Operation Phase

 

3.7.2        For the traffic noise, the measured/monitored noise levels shall be compared with the predicted results and the predicted traffic flow conditions (calculated noise levels based on concurrent traffic census obtained).  In case discrepancies are observed, explanation shall be given to justify the discrepancies. 

 

3.8              Noise Mitigation Measures

 

Construction Phase

 

3.8.1        The EIA has recommended noise control and mitigation measures during the construction and operation phases of the Project. In the event of exceedances or complaints, the Contractor shall be responsible for the design and implementation of these measures which are outlined in Implementation Schedule in Appendix A.

3.8.2        The Contractor is recommended to adopt quiet powered mechanical equipment (PME) for the following construction tasks of the Designated Projects:

·                 Piling activity for construction of temporary breakwater at Causeway Bay Typhoon Shelter

·                 Temporary seawall construction, filling behind seawall, for whole project construction

·                 Diaphragm wall, excavation, construction of slabs and backfilling in CWB tunnel construction

·                 Rock excavation at CWB tunnel (Cross Harbour Tunnel section)

·                 Temporary diversion of cooling water pipeline at CBTS 4

·                 Slip Road 8 and Victoria Park Road re-provisioning and at-grade road construction

·                 Substructure and superstructure for landscape deck, connection of IECL

·                 Demolition of structure

·                 Drainage culverts construction

·                 Ferry pier reprovisioning, including construction of new ferry pier and demolition of existing structure

·                 WSD’s salt water pumping station construction

·                 Construction of Wan Chai East sewage outfall

·                 Road works construction

·                 MTR Tunnel crossing

·                 Cross harbour watermains

·                 Foundation of East Ventilation Building

 

3.8.3        To alleviate the construction noise impact on the affected NSRs, two types of noise barriers (movable and temporary noise barriers during construction) are proposed to be provided for particular items of plant and construction works. The Contractor is recommended to adopt movable noise barriers with a cantilevered upper portion for the following items of plant:

·      Excavator

·                                   Air Compressor

·      Bentonite Plants

·                                   Concrete Pump

·      Poker Vibrator

·                                   Hand-held Breaker

·      Diaphragm Wall Rigs

·                                   Breaker

·      Generator

 

 

3.8.4        Temporary noise barriers (5m in height) with cantilevered upper portion (3.5m in length) are proposed in NPR2W, NPR1, NPR2E work sites along the diaphragm wall of the tunnel section and retaining walls of the tunnel approach ramp for alleviation of construction noise during construction of diaphragm walls and substructures of the tunnel approach ramp.  Temporary noise barriers with height up to the soffit of the bridge deck area are proposed along the existing IEC structure for alleviation of construction noise during the demolition and construction of substructures for the IEC and construction of adjacent tunnel approach ramp structures.  Locations of the temporary noise barriers are presented in Figure 3.4. A 10 dB(A) noise reduction can be achieved by eliminating the line of sight from the receivers along the construction areas.  The barrier material shall have a surface mass of not less than 14 kg/m2 on skid footing with 25mm thick internal sound absorptive lining to achieve the maximum screening effect.

3.8.5        Additionally, apart from the temporary noise barrier as proposed and presented in Figure 3.4, temporary noise barriers to be mounted on the existing piers of IEC are also proposed for the demolition works of existing piers and crossheads of the marine section of the existing IEC. Locations of this type of temporary noise barrier are presented in Figure 3.5.

3.8.6        PMEs grouping for IECL substructure construction works and slip Road 8 at-grade road works, either Group 1 or 2 can be operated at any one time under the construction schedule, are also proposed in order to further minimize noise impact to the receivers.

3.8.7        In addition, there are also many good site practices recommended as follows:

·                   Only well-maintained plant shall be operated on-site and plant shall be serviced regularly during the construction program.

·                   Silencers or mufflers on construction equipment shall be utilised and shall be properly maintained during the construction program.

·                   Mobile plant, if any, shall be sited as far away from NSRs as possible.

·                   Machines and plant (such as trucks) that may be in intermittent use shall be shut down between works periods or shall be throttled down to a minimum.

·                   Plant known to emit noise strongly in one direction shall, wherever possible, be orientated so that the noise is directed away from the nearby NSRs.

·                    Material stockpiles and other structures shall be effectively utilised, wherever practicable, in screening noise from on-site construction activities.

3.8.8        If the above measures are not sufficient to restore the construction noise quality to acceptable levels upon the advice of ET Leader, the contractor shall liaise with the ET Leader to identify further mitigation measures.  They shall be proposed to ER for approval, and the contractor shall then implement these additional mitigation measures.

 

Operation Phase

3.8.9        The following direct mitigation measures, as shown in Figure 3.6, have been proposed in the EIA.

·                    about 500m length of noise semi-enclosure covering the westbound slip road from the IEC

·                    about 230m length of noise semi-enclosure covering the main carriageways (eastbound and westbound) of the CWB and IEC

·                    about 135m length of 5.5m high cantilevered noise barrier with 3m cantilever inclined at 45° on the eastbound slip road to the IEC

·                    about 95m length of 5.5m high cantilevered noise barrier with 1m cantilever inclined at 45° on the eastbound slip road to the IEC

·                    about 350m length of 3.5m high vertical noise barrier on the eastbound slip road to the IEC

 

 

Table 3.2         Event/Action Plan for Construction Noise

EVENT

ACTION

 

ET

IC(E)

ER

CONTRACTOR

Action Level being exceeded

1.       Notify ER, IC(E) and Contractor;

2.       Carry out investigation;

3.       Report the results of investigation to the IC(E), ER and Contractor;

4.       Discuss with the IC(E) and Contractor on remedial measures required;

5.       Increase monitoring frequency to check mitigation effectiveness.

(The above actions should be taken within 2 working days after the exceedance is identified)

1.                                                      Review the investigation results submitted by the ET;

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

3.                                                      Advise the ER on the effectiveness of the proposed remedial measures.

(The above actions should be taken within 2 working days after the exceedance is identified)

1.       Confirm receipt of notification of failure in writing;

2.       Notify Contractor;

3.       In consolidation with the IC(E), agree with the Contractor on the remedial measures to be implemented;

4.       Supervise the implementation of remedial measures.

(The above actions should be taken within 2 working days after the exceedance is identified)

 

1.   Submit noise mitigation proposals to IC(E) and ER;

2.   Implement noise mitigation proposals.

(The above actions should be taken within 2 working days after the exceedance is identified)

 

 

 

 

 

Limit Level being exceeded

1.       Inform IC(E), ER, Contractor and EPD;

2.       Repeat measurements to confirm findings;

3.       Increase monitoring frequency;

4.       Identify source and investigate the cause of exceedance;

5.       Carry out analysis of Contractor’s working procedures;

6.       Discuss with the IC(E), Contractor and ER on remedial measures required;

7.       Assess effectiveness of Contractor’s remedial actions and keep IC(E), EPD and ER informed of the results;

8.       If exceedance stops, cease additional monitoring.

(The above actions should be taken within 2 working days after the exceedance is identified)

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

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

(The above actions should be taken within 2 working days after the exceedance is identified)

1.       Confirm receipt of notification of failure in writing;

2.       Notify Contractor;

3.       In consolidation with the IC(E), agree with the Contractor on the remedial measures to be implemented;

4.       Supervise the implementation of remedial measures;

5.       If exceedance continues, consider stopping the Contractor to continue working on that portion of work which causes the exceedance until the exceedance is abated.

(The above actions should be taken within 2 working days after the exceedance is identified)

1.       Take immediate action to avoid further exceedance;

2.       Submit proposals for remedial actions to IC(E) and ER within 3 working days of notification;

3.       Implement the agreed proposals;

4.       Submit further proposal if problem still not under control;

5.       Stop the relevant portion of works as instructed by the ER until the exceedance is abated.

(The above actions should be taken within 2 working days after the exceedance is identified)