3.                  NOISE

 

3.1              Introduction

 

3.1.1        Noise impact is likely to arise from some of the activities for the construction of KT13. The EIA recommended a number of mitigation measures that should be implemented to reduce potential impacts to acceptable limits. A monitoring programme is recommended for baseline conditions and during the construction phase to evaluate the performance of the proposed measures.

 

3.1.2        This section of the Manual lists all the recommended mitigative and preventive measures in the EIA for the control of construction noise, and the up to date requirements for baseline and construction phase noise monitoring. The Contractor is required to implement these listed measures in the EIA and to undertake noise monitoring as specified in this section, in addition to complying with all noise control related legislation.

 

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 (Leq). Leq(30 min) shall be used as the monitoring parameter for the time period between 0700-1900 hours on normal weekdays.

 

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 B for reference.

 

3.3              Monitoring Equipment

 

3.3.1        As referred to in the Technical Memorandum (TM) issued under the Noise Control Ordinance (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 the presence of fog, rain, wind with a steady speed exceeding 5ms-1 or wind with gusts exceeding 10ms-1. The wind speed shall be checked with a portable wind speed meter capable of measuring the wind speed in m/s. Standard acoustical principles and practices should be observed during monitoring.

 

3.3.3        The Contractor’s ET leader 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 are shown in Table 3.1 and Figure 3.1.  In case works is required for restricted hours, monitoring locations may also include those relevant to the application of Construction Noise Permit (CNPs) as advised by EPD.

 

3.4.2        The status and locations of noise sensitive receivers may change after issuing this manual. In this case, the Contractor’s ET leader shall propose updated monitoring stations and seek approval from ER and agreement from the ICE and EPD of the proposal.

 

Table 3.1

Noise Monitoring Stations for Baseline and Construction Monitoring

Noise Monitoring Stations

Equivalent RNSRs in EIA

Rationale

N1

13b

Closest to proposed work under Section A

N2

13d

Closest to proposed works under Section B

N3

13f

Closest to proposed work for bypass culvert

 

3.4.3        When alternative monitoring stations are proposed, the monitoring locations should be chosen based on the following criteria:

 

(a)                at locations close to the major site activities which are likely to have noise impacts;

 

(b)               close to the noise sensitive receivers (N.B. For the purposes of this section, any domestic premises, hotel, hostel, temporary housing accommodation, hospital, medical clinic, educational institution, place of public worship, library, court of law, performing art centre should be considered as noise sensitive receiver); and

 

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

 

3.4.4        The monitoring station shall normally be at a point 1m from the exterior of the sensitive receivers building facade and be at a position 1.2m 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 +3dB(A) shall be made to the free field measurements.

 

3.4.5        The Contractor’s ET leader shall agree with the ER 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.

 

3.4.6        In case the monitoring location’s windows are normally closed and operate their air condition units, or has fixed windows and operate air conditioning units, alternative locations shall be sought, bearing in mind the criteria listed in Section 3.4.3.

 

3.5              Baseline Monitoring

 

3.5.1        The ET Leader shall carry out baseline noise monitoring prior to the commencement of the construction works. The baseline monitoring shall be carried out continuously for a period of at least one week at interval of 5 minutes. The A-weighted noise level Leq, L10 and L90 shall be recorded. A schedule on the baseline monitoring shall be submitted to the ER for approval before the monitoring starts.

 

3.5.2        The survey period should be selected prior to the commencement of construction activities in order to avoid other atypical noise sources. The proper functioning of the logger shall be ensured during the monitoring period, and as a minimum, the equipment shall be inspected for a period of not less that one hour every two days to ensure its continued operation and to detail specific noise sources audible at the monitoring location. The calibration of the logger kit shall be as recommended by the manufacturer. Measurements shall be recorded to the nearest 0.1 dB.

 

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

 

3.6              Impact Monitoring

 

3.6.1        Impact monitoring shall be carried out at all the designated monitoring station in Table 3.1 during the construction phase of the project. The monitoring frequency for each station on a basis of each calendar week when noise generating activities are underway is as follows:

 

•                     one set of Leq (30min) between 0700-1900 hours on normal weekdays.

 

3.6.2        General construction work carried out during restricted hours is controlled by CNP system under the Noise Control Ordinance (NCO).

 

3.6.3        The Action and Limit Levels for Regular Monitoring are given in Table 3.2 and the Event/Action Plan in Table 3.3.

 

3.7              Event and Action Plan for Construction Noise

 

3.7.1        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. The contractor’s ET shall provide full documentation of his investigation on the cause of the non-compliance and whether it can be traced to activities other than those caused by the project, to the satisfaction of the ER and the IEC.

 

Table 3.2

Action and Limit Levels for Construction Noise

 

 

Time Period

Action

Limit

Normal hours

0700-1900 hrs on normal weekdays

When one documented complaint is received

75* dB(A)

 

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

 

3.8              Construction Noise Mitigation Measures

 

3.8.1        To mitigate construction noise impacts, gap-free noise barriers made of material at least 10 kg/m² shall be installed at locations as indicated in Figure 3.2 shall be maintained throughout the construction period. The Contractor shall also used quiet powered mechanical equipment as well as conduct good site practices throughout the construction period.

 

Table 3.3  Event/Action Plan for Construction Noise Monitoring

EVENT

ACTION

Contractor’s ET Leader

IEC

ER

Contractor

 

 

 

 

 

Action Level

1.     Notify IEC, Contractor and ER

2.     Carry out investigation

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

4.     Discuss with the Contractor and formulate remedial measures

5.     Double monitoring frequency

6.     Check compliance to Action/Limit Levels after application of mitigation measures

1.     Review the analysed results submitted by the Contract’s ET leader

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

3.     Review the implementation of remedial measures

1.     Confirm receipt of notification of complaint 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 ER and IEC

2.     Implement noise mitigation proposals

 

 

 

 

 

 

 

 

 

 

Limit Level

1.     Notify IEC, ER, EPD and Contractor

2.     Identify Source

3.     Repeat measurement 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 IEC, ER and EPD the causes & actions taken for the exceedances

7.     Assess effectiveness of Contractor’s remedial actions and keep IEC, EPD and ER informed of the results

8.     If exceedance stops, cease additional monitoring

1.     Discuss amongst ER, Contractor’s ET leader and Contractor on the potential remedial actions

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

3.     Audit 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

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 actions to 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