3 NOISE

3.1 Introduction

3.1.1 Representative noise sensitive receivers (NSRs) along the proposed alignment have been identified and assessed in the EIA Report. The locations of the representative NSRs are shown in Figure 3.1. It is predicted that some NSRs will be subjected to daytime and restricted hour construction noise. The monitoring programme shall be carried out by the ET to ensure that the noise level of construction works complies with the criteria of the Noise Control Ordinance (NCO) and noise criteria laid down by the contract.

3.2 Noise Parameters

3.2.1 The construction noise level shall be measured in terms of the A-weighted equivalent continuous sound pressure level (L_eq). L_{eq (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, L_{eq (5 minutes)} shall be employed for comparison with the Noise Control Ordinance (NCO) criteria.

3.2.2 As supplementary information for data auditing, statistical results such as L₁₀ and L₉₀ shall also be obtained for reference. A sample data record sheet is shown in Appendix B2 for reference.

3.3 Monitoring Equipment

3.3.1 As referred 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 should not be made in the presence of fog, rain, and 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 meter per second.

3.3.3 The ET is responsible for 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 Baseline Monitoring

3.4.1 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. A schedule of baseline monitoring shall be submitted to the ER for approval before the monitoring starts.

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

3.4.3 In exceptional cases, when insufficient baseline monitoring data or questionable results are obtained, the ET 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.

3.5 Impact Monitoring of Construction Noise Impact

3.5.1 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 per week basis when noise generating activities are underway:

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

3.5.2 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 proved to be irrelevant to the construction activities.

3.5.3 A schedule on the compliance monitoring shall be submitted to the ER and IC(E) for approval before the monitoring starts.

3.5.4 The locations of construction noise monitoring stations are summarised in Table 3.1 and shown in Figure 3.2.

Table 3.1 Noise Monitoring Stations during Construction Phase

CWB & IECL	Noise Monitoring Station	Noise Monitoring Location
Central Interchange Section	M1	Korea Centre
Exhibition Section	M2	Causeway Bay Centre
IECL Section	M3	Marco Polo Mansion
IECL Section	M4	Victoria Centre

3.5.5 Owing to the nature of the works under the project, construction activities will shift from one location to another from time to time. The ET shall select the monitoring locations from those in Table 3.1 based on the locations of the construction activities and seek approval from ER and agreement from the IC(E) and EPD to the proposal. The monitoring locations should be chosen based on the following criteria:

· at locations close to the major site activities which are likely to have noise impacts;

· close to the most affected existing noise sensitive receivers; and

· for monitoring locations located in the vicinity of the sensitive receivers, care should be taken to cause minimal disturbance to the occupants during monitoring.

3.5.6 The monitoring station shall normally be at a point 1 m from the exterior of the sensitive receiver building facade and be at a position 1.2 m 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. For reference, a correction of +3 dB(A) shall be made to the free field measurements. The ET shall agree with the IC(E) 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.

3.6 Event And Action Plan For Construction Noise

3.6.1 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 Action Plan in Table 3.3, shall be carried out.

Table 3.2 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) *

Note : If works are to be carried out during restricted hours, the conditions stipulated in the construction noise permit issued by the Noise Control Authority have to be followed.

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

Table 3.3 Event / Action Plan for Construction Noise

EVENT

ACTION

IC(E)

CONTRACTOR

Action Level

1. Identify source, investigate the causes of exceedance and propose remedial measures;

2. Notify IC(E) and Contractor;

3. Report the results of investigation to the ER 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 ER accordingly;

3. Supervise the implementation of remedial measures.

1. Confirm receipt of notification of failure in writing;

2. Notify Contractor;

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

4. Ensure remedial measures are properly implemented.

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

2. Implement noise mitigation proposals.

Limit Level

1. Identify source;

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

3. Repeat measurements 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 IC(E), ER and EPD the causes and actions taken for the exceedances;

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 Contractors 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 Contractor;

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

4. Ensure remedial measures properly implemented;

5. If exceedance continues, consider what portion of the work is responsible and instruct the Contractor to stop that portion of work until the exceedance is abated.

1. Take immediate action to avoid further exceedance;

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

3. Implement the agreed proposals;

4. Resubmit proposals if problem still not under control;

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

3.7 Noise Mitigation Measures

3.7.1 The EIA Report has recommended the following construction noise control and mitigation measures during construction.

Construction Phase

3.7.2 The Contractor shall be responsible for the design and implementation of the following measures. The key measures are :

· use of quieter and silenced equipment for road construction and site development;

· use of movable noise barriers for particular plant;

· reduction of on-time operation of the powered mechanical equipment during the construction of Bridge M, demolition of the existing Island Eastern Corridor and CWB tunnel near the Hong Kong Convention and Exhibition Centre.

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

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

· silencers or mufflers on construction equipment should be utilised and should be properly maintained during the construction program;

· mobile plant, if any, should be sited as far away from NSRs as possible;

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

· plant known to emit noise strongly in one direction should, where possible, be orientated so that the noise is directed away from nearby NSRs; and

· material stockpiles and other structures should be effectively utilised, where practicable, in screening noise from on-site construction activities.

3.7.4 If the above measures are not sufficient to restore the construction noise quality to an acceptable level 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.

3.8 Operational Phase Noise Monitoring

3.8.1 As the noise sensitive receivers close to the proposed road will be exposed to traffic noise during the operational phase, a noise monitoring programme shall be developed to include noise measurements at noise sensitive receivers during the peak traffic hour. The programme shall be carried out by the Environmental Team (ET) to ensure that the traffic noise levels are comparable to those predicted in the EIA under the full provision of the mitigation measures recommended. Operational noise monitoring will also be required during commissioning stage of ventilation buildings to ensure that the compliance with the noise limits specified in the EIA Report has been achieved. The HyD will be responsible for the operational phase monitoring.

Traffic Noise

Noise Parameters

3.8.2 The traffic noise level shall be measured twice within the first year of the road opening. Measurement shall be made in terms of the A-weighted L₁₀ over three half-hour periods during the peak traffic hour. Other metrics like L_eq may be added as seen fit. A sample data record sheet is shown in the Appendix D. More details could be referred to Section 3.8.3.

Monitoring Equipment

3.8.3 Sound level meters to be used shall be in compliance with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications 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(A).

3.8.4 Noise measurement should be made in accordance with standard acoustical principles and practices in relation to weather conditions.

3.8.5 The ET Leader is responsible for the provision and maintenance 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.

Monitoring Locations

3.8.6 The operational noise monitoring locations are shown in Figure 3.3 and are summarised in Table 3.4. The status and locations of noise sensitive receivers may change after issuing the Environmental Monitoring and Audit Manual. In such cases, the ET Leader shall propose updated monitoring locations and seek approval from the Engineer’s Representative, and agreement from the IC(E) and EPD to the proposal. The monitoring locations are based on the following criteria for selection:

(a) They should be at NSRs in the vicinity of recommended direct technical remedies;

(b) One high floor and one medium floor monitoring points should be chosen at each location as far as possible; and

(c) 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.

Table 3.4 Noise Monitoring Stations during Operational Phase

Noise Monitoring Station	Noise Monitoring Location
OM1	Marco Polo Mansion
OM2	Belle House

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

(a) they shall be similarly exposed to potential noise impacts;

(b) they shall be close to the noise sensitive receivers; and

3.8.8 The operational noise monitoring shall be carried out 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.

Baseline Monitoring

3.8.9 No baseline operational noise monitoring is required.

Impact Monitoring

3.8.10 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 :

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

(b) one set of measurements at the evening traffic peak hour on normal weekdays;

(c) a concurrent census of traffic flow and percentage heavy vehicle shall be obtained for far-side and near-side of the road and the existing road network in the vicinity of each measuring point;

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

(e) the two sets of monitoring data should be obtained within the first year of operation.

3.8.11 Measured noise levels should be compared with predicted noise levels by applying appropriate conversion corrections to allow for the traffic conditions at the time of measurement. Appendix D shows a sample data record sheet for operational noise monitoring.

Noise Mitigation Measures

3.8.12 In the EIA Report, a series of mitigation measures have been considered for the proposed road to reduce the noise impacts at the NSRs. The mitigation measures include:

IECL Section

· a 107 m long semi-enclosure for the eastbound carriageway of IECL (CH4883 – CH4990);

· a 57 m long semi-enclosure for the westbound carriageway of IECL (CH4883 – CH4940)

· a 113 m long and 7 m high vertical barrier, located at the edge of the parapet of the westbound carriageway of IECL (CH4770 – CH 4883);

· a 210 m long and 7 m high vertical barrier located at the edge of the parapet of the Slip Road J (CH350 - CH560);

· a 139 m long and 5.5 m high vertical barrier, located at the edge of the parapet of the westbound carriageway of IECL (CH4116 – CH4255);

· a 140 m long and 4 m high vertical barrier, located at the edge of the parapet of the westbound carriageway of IECL (CH4630 – CH4770);

· a 81 m long cantilevered barrier (5.5 m high vertical barrier with 2 m cantilever length at 45 degrees to the horizontal) located at the central divider of IECL (CH4802 - CH4883); and

· a 259 m long cantilevered barrier (5.5 m high vertical barrier with 2 m cantilever length at 45 degrees to the horizontal) located at the edge of the parapet of the westbound carriageway of IECL (CH4255 – CH4514).

Event and Action Plan

3.8.13 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 should be given to justify the discrepancies.

Fixed Plant Noise

3.8.14 It is recommended that noise monitoring is carried out for the ventilation buildings on two occasions: Day one of commissioning and Day 60 of operation.

3.8.15 Noise measurements shall be made in accordance with the procedures outlined in the ‘Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places and Construction Sites’ (IND-TM) and shall be conducted at a time when the ventilation buildings are operating at maximum capacity.

3.8.16 The monitoring location shall be outside the ventilation buildings at a distance of 1 m from the centre of the louvre. Two types of measurement shall be carried out:

(a) Broadband measurement of L_eq _{(30 minutes)} dB(A). Shorter measurement period may be used if it can be demonstrated that the noise level is constant.

(b) Frequency analysis between 31.5 Hz and 16 kHz measured at 1/3 octave intervals. If the noise emanating from the louvre is found to be tonal (as defined in IND-TM) then an appropriate tonal correction should be applied to the measured noise level to achieve the corrected noise level (CNL). The CNL shall be compared with the noise specifications.