3                         Noise

3.1                   Introduction

3.1.1             In this section, the requirements, methodology, equipment, monitoring locations, criteria and protocols for the monitoring and audit of noise impacts during the construction phase and the operation phase of the Project are presented.

3.1.2             Construction noise impacts from the Project at the identified noise sensitive receivers (NSRs) are predicted during the construction phase. Noise mitigation measures will be required to reduce noise levels to the stipulated standard. A noise monitoring programme shall be undertaken to ensure such mitigation measures would be implemented properly.

3.1.3             According to the EIA, road traffic noise levels should be monitored at representative NSRs, which are in the vicinity of the recommended direct mitigation measures, during the first year after road opening. The purpose of the monitoring is to ascertain that the noise levels would comply with the noise criteria at the sensitive receivers, and that the recommended mitigation measures are effective in suppressing the noise levels.

3.2                   Noise Parameters

3.2.1             The construction noise levels 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             The road traffic noise level shall be measured twice within the first year of the road opening.  Measurement shall be made in terms of A-weighted equivalent L10 (1-hour). Other metrics like Leq may be added as seen fit.  During the traffic noise measurement, traffic count shall also be undertaken concurrently.

3.2.3             Supplementary information for data auditing, statistical results such as L10 and L90 shall also be obtained for reference.  Sample data record sheets based on the one presented in the EM&A Guidelines for Development Projects in Hong Kong, are shown in Appendices C and D.  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 IC(E).

3.3                   Monitoring Requirement and 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 shall be accepted as valid only if the calibration levels before and after the noise measurement agree to within 1.0 dB.

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

3.3.3             The ET is responsible for the provision of sufficient and suitable noise measuring equipment and associated instrumentation 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 for Construction Noise

3.4.1             The EIA Report indicated that two worst affected locations are designated for construction noise monitoring as listed in Table 3.1 and illustrated in Figure 3.1.  The status and locations of noise sensitive receivers may change after issuing this manual. If such case exists, the ET Leader shall propose updated monitoring locations and seek approval from EPD and agreement from the ER and the IC(E) before baseline monitoring commences.

Table 3.1             Noise Monitoring Stations during Construction Phase

Identification No.

Noise Monitoring Location

TLLF

The Church of Christ in China Tam Lee Lai Fun Memorial Secondary School

LB1

Lakeshore Building

 

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

Ÿ               Monitoring at sensitive receivers close to the major site activities which are likely to have noise impacts;

Ÿ               Monitoring at the NSRs as defined in the TM; and

Ÿ               Assurance of minimal disturbance to the occupants during monitoring.

3.4.3             The monitoring station shall normally be at a point 1 m from the exterior of the noise sensitive facade and be at a position 1.2 m above ground.  If there is a problem with access to the normal monitoring position, an alternative position shall 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 shall agree with the IC(E) and EPD 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.

3.5                   Baseline Monitoring for Construction Noise

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 14 consecutive days at a minimum logging interval 30 minutes (as 6 consecutive LAeq, 5min readings) for daytime and 15 minutes (as 3 consecutive LAeq,5min readings) for evening time and night time.  The Leq, L10 and L90 shall be recorded at the specified interval.  A schedule on the baseline monitoring shall be prepared by the ET and submitted to the IC(E) and EPD for approval before the monitoring starts.

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 IC(E) and EPD to agree on an appropriate set of data to be used as a baseline reference and submit to the ER for approval.

3.6                   Impact Monitoring for Construction Noise

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

Ÿ               one set of measurement 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 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 3.3, 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.

3.7                   Event and Action Plan for Construction Noise

3.7.1             The Action and Limit levels for construction noise are defined in Table 3.2.  Should non-compliance of the criteria occur, action in accordance with the Event and Action Plan in Table 3.3 shall be implemented.


Table 3.2             Action and Limit Levels for Construction Noise

Time Period

Action Level

Limit Level dB(A)

0700 – 1900 hours on normal weekdays

When one documented complaint is received

70/65# (TLLF)

75 (others)

1900-2300 on all days and 0700-2300 on general holidays (including Sundays)

60/65/70 dB(A)*

2300-0700 on all days

45/50/55 dB(A)*

Note:    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.

* For normal daytime working hours, the noise criteria are 70 dB(A) and 65 dB(A) for normal teaching periods and examination periods, respectively.

 

3.8                   Construction Noise Mitigation Measures

3.8.1             The EIA report indicated that construction activities at the proposed construction site would cause noise exceedance at some existing NSRs in the vicinity of the site. Therefore, appropriate mitigation measures and good site practices are recommended to be properly implemented. The mitigation measures recommended in the EIA report are summarised below:

Ÿ               Use of quiet powered mechanical equipment (PME). The recommended quiet PME are taken from the BS 5228: Part 1: 1997 and the PME are known to be available in Hong Kong.

Ÿ               Use of movable noise barrier (3m high) for PMEs when the following construction activities undertaken in the vicinity of NSR TLLF.  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.

(i)                  road marking and road paving

(ii)                construction of noise barriers (movable barrier for excavator and compressor only);

Ÿ               The work area of road marking should be located not less than 18m from NSR TLLF during examination period.

Ÿ               Piling operation for construction of noise barrier should also be ceased during examination period of NSR TLLF.

Ÿ               Scheduling of PMEs for road paving activity in the vicinity of NSR TLLF, only one PME (asphalt paver or vibratory roller) to be operated during normal teaching period.

Ÿ               During examination period, cease operation of PMEs if work area of road paving less than 30m from NSR TLLF or only one PME (asphalt paver or vibratory roller) is allowed to be operated if the work area is not less than 22m from NSR TLLF.

Ÿ               Implementation of the following good site practices:

Ø          only well-maintained plant shall be operated on-site and plant shall be serviced regularly during the construction program;

Ø          silencers or mufflers on construction equipment shall be utilised and shall be properly maintained during the construction program;

Ø          mobile plant, if any, shall be sited as far away from NSRs as possible;

Ø          machines and plant (such as trucks) that may be in intermittent use shall be shut down between work periods or throttled down to a minimum;

Ø          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; and

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

3.8.2             The implementation schedule for the recommended mitigation measures is presented in Appendix A.

Table 3.3             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.

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.

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.

 

1.   Submit noise mitigation proposals to ET and ER;

2.   Implement noise mitigation proposals.

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.

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.

 

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.

1.        Take immediate action to avoid further exceedance;

2.        Submit proposals for remedial actions to ET 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.

3.9                   Operational Traffic Noise Monitoring

3.9.1             The ET shall prepare and deposit to EPD, at least 6 months before the operation of the works under the Project, a monitoring plan for the purpose of assessing the accuracy of traffic noise predictions by comparing the project noise impact predictions with the actual impacts.  The monitoring plan shall contain monitoring locations, monitoring schedules, methodology of noise monitoring including noise measurement procedures, traffic counts and speed checks, and methodology of comparison with the predicted levels.   The ET shall implement the monitoring plan in accordance with the deposited monitoring plan unless with prior justification.  Monitoring details and results including the comparison between the measured noise levels and the predicted levels shall be recorded in a report to be deposited with EPD within one month of the completion of the monitoring.  The report shall be certified by the ET Leader and the Project Proponent before deposit with EPD.

3.9.2             The traffic noise levels shall be measured twice at 6-month intervals within the first year upon completion of the Project.  Measurements shall be made in terms of the A-weighted L10 over 3 half hour periods during the peak traffic hour, other metrics like Leq may be added as seen fit.

3.9.3             As shown in Table 3.4, three designated monitoring stations are selected for operational noise monitoring.  Figure 3.1 describes the operational noise monitoring locations, which are also depicted in.  The status and locations of noise sensitive receivers may change after this Manual is issued.  If such cases exist, the ET Leader shall propose updated monitoring locations and seek approval from the ER and IE(C) and agreement from EPD of the proposal.

Table 3.4             Noise Monitoring Stations during Operational Phase

Identification No.

Noise Monitoring Location

TMHQ

Block F, Tuen Mun Hospital Quarter

VB

Victory Building

MYS

SKH Mung Yan Primary School

LB1

Lakeshore Building

 

 

3.9.4             The monitoring locations shall be selected according to the following criteria:-

Ÿ               they should be at NSRs in the vicinity of recommended direct technical remedies; preferably, there should be one representative monitoring locations near each types of noise screening element (i.e. vertical barrier, cantilever barrier and enclosure);

Ÿ               one high floor and one medium floor monitoring points should be chosen at each location as far as possible; and

Ÿ               selected monitoring locations should enable monitoring to be done twice within one year after implementation of the mitigation measures during operation of the proposed road

3.9.5             The status and location of NSRs may change after issuing this manual. If such case exists, the ET Leader shall propose updated monitoring locations and seek approval from EPD and agreement from the ER and the IC(E) before baseline monitoring commences.

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

Ÿ               alternative location shall be similarly exposed to potential noise impacts;

Ÿ               it shall be close to the NSRs; and

Ÿ               shall be located so as to cause minimal disturbance to the occupants.

3.9.7             The operational noise monitoring shall be carried out at a distance of 1 m from the openable window and 1.2 m above the floor level of the noise sensitive receivers identified.  The ET Leader shall agree with the IC(E) on any necessary corrections adopted.

3.9.8             Traffic noise monitoring shall be carried out at all the designated traffic noise monitoring stations.  The following is an initial guide on the traffic noise monitoring requirements during the operational phase:

Ÿ               one set of measurements at the morning traffic peak hour on normal weekdays;

Ÿ               one set of measurements at the evening traffic peak hour on normal weekdays;

Ÿ               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;

Ÿ               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

Ÿ               the two sets of monitoring data shall be obtained within the first your of operation.

3.9.9             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.  A sample data record sheet for traffic noise monitoring is shown in Appendix D.

3.9.10         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.