6.                    NOISE

6.1                    Noise Quality Parameters

6.1.1                        Construction noise level shall be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq). Leq 30 min 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 min shall be employed for comparison with the Noise Control Ordinance (NCO) criteria.

6.1.2                        As supplementary information for data auditing, statistical results such as L10 and L90 shall also be obtained for reference.

6.2                   Monitoring Equipment

6.2.1                        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 agrees to within 1.0 dB.

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

6.2.3                        The ET is responsible for the provision, installation, operation, maintenance, dismantle 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.

6.3                   Monitoring Locations

6.3.1A  The locations of construction noise monitoring stations are summarised in Table 6.1 and shown in Figure 6.1.

6.3.2                        The ET shall select the monitoring location from the above table based on the locations of the construction activities and seek approval from ER and agreement from the IEC and EPD to the proposal. The monitoring locations should be chosen based on the following criteria:

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

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

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

6.3.3                        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 IEC 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.

6.3.4                        The ENPO may, depending on site conditions and monitoring results, decide whether additional monitoring locations shall be included or any monitoring locations could be removed/relocated during any stage of the construction phase.

6.4                  Baseline Monitoring for Construction Noise

6.4.1                        The ET shall carry out baseline noise monitoring prior to the commencement of the construction works. There shall not be any construction activities in the vicinity of the stations during the baseline monitoring. Continuous baseline noise monitoring for the A-weighted levels Leq, L10 and L90 shall be carried out daily for a period of at least two weeks in a sample period of 5 minutes or 30 minutes between 0700 and 1900, and 5 minutes between 1900 and 0700. A schedule on the baseline monitoring shall be submitted to the ER and IEC for approval before the monitoring starts.

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

6.4.3A  The baseline monitoring was undertaken for the Project between September and November 2011 under Agreement CE No.35/2011 (EP) “Baseline Environmental Monitoring for Hong Kong–Zhuhai-Macao Bridge Hong Kong Projects – Investigation” prior to commencement of construction of the Project. The baseline monitoring results obtained under Agreement CE No.35/2011 (EP) will be adopted for this Contract.

6.5                   Impact Monitoring for Construction Noise

6.5.1                        During normal construction working hour (0700-1900 Monday to Saturday), monitoring of Leq, 30min noise levels (as six consecutive Leq, 5min readings) shall be carried out at the agreed monitoring locations once every week in accordance with the methodology in the TM.

6.5.2                        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.

6.5.3                        In case of non-compliance with the construction noise criteria, more frequent monitoring, as specified in the Action Plan, 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.

6.5.4                        A schedule on the compliance monitoring shall be submitted to the ER and IEC for approval before the monitoring starts.

6.6                  Event and Action Plan for Construction Noise

6.6.1A    The Action and Limit levels for construction noise are defined in Table 6.2. Should non-compliance of the criteria occur, action in accordance with the Action Plan in Table 6.3 shall be carried out.

6.7                   Mitigation Measures

6.7.1                        The EIA Report has recommended construction noise control measures including the use of quiet plant and temporary noise barriers. All the proposed mitigation measures are summarised in the EMIS in Appendix B.

6.7.2                        Not applicable.

6.8A        Report of Monitoring Data to ENPO

6.8.1A    This Assignment, which involves multiple construction contracts, will be constructed concurrently with other major infrastructures such as the HKLR and TMCLKL. These interface projects will be overviewed by the ENPO. The ENPO will also oversee and coordinate the cumulative environmental issues arising from the concurrent projects.

 

6.8.2A    To facilitate the ENPO to evaluate environmental impacts and investigate complaints, the ET Leaders shall provide the impact noise monitoring results within one working day after the monitoring event. The ET Leader shall follow ENPO's requirement on the data submission format and procedure.