3                                  Noise

3.1                            Introduction

The general requirements, methodology, equipment, and mitigation measures for the monitoring and audit of noise impacts associated with the construction and operation of the Project are described below.

3.2                            Noise Generation Activities

3.2.1                      Construction Phase

The main construction activities to cause noise impacts are:

·           Construction of the temporary steel platform and bridge at the Short Access Route;

·           Enabling works along the Long Access Route; and

·           Construction works at Project Site.

3.2.2                      Operational Phase

The sources of noise emitted from the operating the wind turbine include the rotation of mechanical and electrical equipment and aerodynamic noise originating from the flow of air around the blades. 

3.2.3                      Noise Sensitive Receivers

All NSRs, as defined by EIAO-TM, and the nearest NSRs have been identified.  The locations of the NSRs have been shown in Figure 3.2a and Table 3.2a.  No planned NSR is identified within 2 km of the Project Site. 

Table 3.2a      Identified Noise Sensitive Receivers

NSR

Location

No. of Floors

Distance to the Project Site (m)

N1

Hei Ling Chau Correctional Institution

1

740m

N2

Hei Ling Chau Addiction Treatment Centre (Annex)

1

380m

N3 (a)

Staff Quarters

1

Approx. 2,000m

Note:

(a)   Only applicable for assessment of the construction noise impacts associated with the enabling works along the Long Access Route.  It is a bungalow type accommodation not designed for family units.  Site visit indicated that the quarter has not been occupied for sometime

 

3.3                            Environmental Monitoring and Audit

3.3.1                      Methodology and Criteria

Construction Phase

The construction noise level will be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq) for a period of 30 minutes between 07:00 and 19:00 hours on normal weekdays.  For all other time periods, Leq, 15 minutes will be employed for comparison with the Noise Control Ordinance (NCO) criteria.

Whilst the NCO does not provide the statutory control of construction activities occurring on weekdays during normal working hours (i.e. Monday to Saturday inclusive 07:00-19:00 hours), a day-time standard of 75dB(A) Leq, 30 minute stipulated in Annex 5 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) shall be used as the appropriate criterion for all residential dwellings.

The NCO provides statutory controls on general construction works during restricted hours (i.e. 19:00-07:00 hours Monday to Saturday and at any time on Sundays and public holidays).  The Acceptable Noise Levels (ANLs) for evenings and holidays and for night-time are dependent on the Area Sensitivity Rating at the NSR.  The relevant ANLs are provided in Table 3.3a.

Table 3.3a      ANLs to be used as Construction Noise Criteria

Time period

Area Sensitivity Rating (dB(A))

 

A

B

C

All days during the evening (ie 19:00-23:00 hrs) and general holidays (including Sundays) during the day and evening (ie 07:00-23:00 hrs)

60

65

70

All days during the night-time (ie 23:00-07:00 hrs)

45

50

55

As the Project Site is located in a rural area and no influencing factors affect the NSRs, an ASR of “A” has been assigned. 

Operational Phase

The EIAO-TM and Technical Memorandum on Noise From Places Other than Domestic Premises, Public Places or Construction Sites (IND-TM) specifies the applicable Acceptable Noise Levels (ANLs) for operational noise of wind turbine system.  The ANLs are dependent on the Area Sensitivity Rating (ASR) and the time of the day and are presented in Table 3.3b.

Table 3.3b      ANLs to be used as Operation Noise Criteria

Time Period

LAeq 30min (dB(A))

ASR “A”

ASR “B”

ASR “C”

Daytime 07:00-19:00

60

65

70

Evening 19:00-23:00

60

65

70

Night-time 23:00-07:00

50

55

60

Fixed Plant Noise

Noise associated with the operation of wind turbine is controlled under Section 13 of the NCO and the predictions will be undertaken in accordance with the IND-TM.  The criteria noise limits are set out in the EIAO-TM as follows:

·           the total fixed source noise level at the facade of the nearest NSR is at least 5 dB(A) lower than the appropriate ANL (as shown in Table 5.4) as specified in the Technical Memorandum on Noise from Places other than Domestic Premises, Public Places or Construction Sites (IND-TM); or,

·           where the prevailing noise level in the area is 5 dB(A) or more below the appropriate ANL, the total fixed source noise level must not exceed this noise level. 

The criteria noise limits stipulated in the IND-TM are dependent on the Area Sensitivity Rating (ASR) of the NSRs as shown in Table 3.3b.

As the Project Site is located in a rural area and no influencing factors affect the NSRs, an ASR of “A” has been assigned.  Background noise measurement has been conducted to investigate the prevailing noise level in the Study Area.  A 24-hour continuous measurement of prevailing free field noise levels in the vicinity of Hei Ling Chau Correctional Institution (N1) gave levels in the range 42 to 56 dB(A) Leq, 30min.  With the inclusion of façade correction, the measured prevailing noise level will be equal to the (ANL – 5) criterion, and therefore the (ANL – 5) criterion, ie 45 dB(A) Leq, 30min for night-time period will be considered as the stipulated noise limit for the assessment of operational noise impact. 

3.3.2                      Monitoring Equipment

The Environmental Team (ET) will be responsible for providing and maintaining a sufficient number of sound level meters to conduct the necessary impact monitoring and ad hoc monitoring at the agreed monitoring location.

Sound level meters and calibrators will comply with the International Electrotechnical Commission (IEC) Publication 651 : 1979 (Type 1) and 804 : 1985 (Type 1) specification as referred to in the GW-TM & IND-TM.  The sound level meters will be supplied and used with the manufacturers recommended wind shield and with a tripod.

The calibration of the sound level meters will be carried out in accordance with the manufacturer's requirements.  The sound level meters, including the calibrators, will be verified by the manufacturers once every two years to ensure that they perform to the same level of accuracy as stated in the manufacturers specifications.  Calibrated hand-held anemometers capable of measuring the wind speed in m s-1 will also be supplied for the measurement of wind speeds during noise monitoring periods.  The anemometers will be used and calibrated in accordance with the manufactures recommendations.

Sound level meters will be calibrated using a portable calibrator before and after each measurement.  The calibration levels will be noted with the measurement results and where the difference between the calibration levels is greater than 1 dB(A) the measurement will be repeated.

The ET Leader will ensure the equipment will be kept in a good state of repair in accordance with the manufacturer's recommendations and maintained in proper working order with sufficient spare equipment available in the event of breakdown to maintain the planned monitoring programme.

Noise measurements will not be made in the presence of fog, rain, wind with a steady speed exceeding 5 m s-1 or wind with gusts exceeding 10 m s-1.  The wind speed will be checked with the hand-held anemometers.

3.3.3                      Monitoring Locations

The ET will be responsible for conducting noise monitoring at the following representative monitoring locations, as defined in Tables 3.3c and 3.3d during construction and operational phases respectively.  

Table 3.3c      Representative Monitoring Locations during Construction Phase

NSR No.

Description

N2

Hei Ling Chau Addiction Treatment Centre (Annex)

N3

Staff Quarters (a) (b)

Notes:

(a)       Noise monitoring at NSR N3 will be discontinued after the completion of the enabling works at this location.

(b)       If CSD could arrange not to use this staff quarter, there will be no potential noise impact to this NSR.  Noise monitoring will not be required at this location 

Table 3.3d      Representative Monitoring Location during Operational Phase

NSR No.

Description

N2

Hei Ling Chau Addiction Treatment Centre (Annex)

The monitoring location will normally be at a point 1 m from the exterior of the sensitive receiver building façade and at a height approximately 1.2 m above the ground or at the height that has the least obstructed view of the construction activity in relation to the receiver.  For reference, a correction of +3 dB(A) will be made to the free field measurements.  

3.3.4                      Baseline Monitoring

The ET will carry out baseline noise monitoring prior to the commencement of the construction works.  The baseline monitoring will be measured for a continuous period of at least 14 consecutive days at a minimum logging interval of 30 minutes for day-time (between 07:00 and 19:00 hours of normal weekdays) and 15 minutes (as three consecutive Leq, 5 minutes readings) for evening time (between 19:00 and 23:00 hours of normal weekdays), general holidays including Sundays (between 07:00 and 23:00 hours) and night-time (between 23:00 and 07:00 of all days).  The Leq, L10 and L90 will be recorded at the specified interval.  A schedule on the baseline monitoring will be submitted to the EPD for information before the monitoring starts.

There will not be any construction activities in the vicinity of the stations during the baseline monitoring.  Appropriate set of data will be used as a baseline reference and will be submitted to EPD for information.

3.3.5                      Impact Monitoring

Construction Phase

Noise monitoring will be undertaken at the identified NSRs during the construction phase to ensure the compliance to acceptable noise levels.  Noise monitoring will be undertaken at the two representative monitoring locations with a frequency of once a week to obtain one set of 30-minute measurement between 07:00 and 19:00 hours on normal weekdays.  Regular site audits (ie once a month) will be conducted to ensure that the proposed mitigation measures are implemented properly and that the plant inventory used on site is consistent with the assumptions used in the EIA Report. 

If construction works are extended to include works during the hours of 19:00 – 07:00 hours, or general holidays and Sundays, impact monitoring in terms of 3 consecutive Leq, 5 minutes will be carried out at a minimum frequency of once a week during evening, general holiday or night-time works.  Applicable CNP under NCO will be obtained by the Contractor.

In case of non-compliance with the construction noise criteria, more frequent monitoring, as specified in Event/Action Plan in Table 3.3g will be carried out.  Additional monitoring will be continued until the recorded noise levels are rectified or proved to be irrelevant to the construction activities.

Operation Phase

Noise monitoring will be undertaken at the nearest NSR (ie Hei Ling Chau Addiction Treatment Centre (Annex) (N2)) during the night-time period at the agreed monitoring location to ensure the compliance with the stipulated noise criterion.  As wind speed will vary throughout the year and hence the potential noise impacts.  It is recommended to monitor noise levels at monthly intervals for the first 12 months of the operation of the wind turbine.   The monitoring frequency will increase to biweekly intervals during the higher wind speed months (ie winter months - from December to January), and storm season – (July).

Two types of measurement will be carried out:

(a)       Broadband measurement of LAeq (t).  Note that the measurement period (t) shall normally be 30 minutes (six consecutive 5-minute measurements).  However, if it can be demonstrated that the noise level is constant, then a shorter measurement period (no less than 5 minutes) may be used.

(b)       Frequency analysis between 31.5 and 16 kHz measured at 1/3 octave intervals.  If the noise emanating from the wind turbine is found to be tonal (as defined in IND-TM) then an appropriate tonal correction will be applied to the measured noise level (MNL) to achieve the corrected noise level (CNL).  This CNL will be compared with the noise criterion.

3.3.6                      Event and Action Plan

Construction Noise

The action and limit levels for construction noise are defined in Table 3.3e.  Should non-compliance of the criteria occurs, action in accordance with the Event/Action Plan in Table 3.3g will be carried out.  If exceedances are resulted from cumulative impacts, all steps stipulated in the Event/Action Plan will be carried out.

Table 3.3e          Action and Limit Levels for Construction Noise

Time Period

Action Level

Limit Level

07:00 – 19:00 hours on normal weekdays

When one documented complaint is received from any one of the sensitive receivers

75 dB(A)

19:00-23:00 hours on all days and 07:00-23:00 hours on general holidays (including Sundays)

60dB(A)

23:00-07:00 hours on all days

45dB(A)

Operational Noise

The action and limit levels for the operational noise for every 30 minutes are defined in Table 3.3f.  Should non-compliance of the criteria occurs, action in accordance with the Event/Action Plan in Table 3.3h will be undertaken.  If exceedances are resulted from cumulative impacts, all steps stipulated in the Event/Action Plan will be carried out.

Table 3.3f      Action and Limit Levels for Operational Noise

Time Period

Action Level

Limit Level

Day-time (ie 07:00-19:00 hrs)

When one documented complaint is received from any one of the sensitive receivers; or

Noise monitoring results indicate tonal, impulsive or intermittent characteristics.

55 dB(A)

Evening (ie 19:00-23:00 hrs)

55 dB(A)

Night-time (ie 23:00-07:00 hrs)

45 dB(A)

Table 3.3g     Event / Action Plan for Construction Noise

 

Action

Event

ET Leader

CAPCOER

Contractor

Action Level

1.  Notify the Contractor.

2.  Carry out investigation.

3.  Report the results of investigation to the Contractor.

4.  Discuss with the Contractor and formulate remedial measures.

5.  Increase monitoring frequency to check mitigation measures.

 

1. Confirm receipt of notification of exceedance in writing.

2. Notify the Contractor.

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

4. Ensure remedial measures are properly implemented.

1. Submit noise mitigation proposals to the CAPCOER.

2. Implement noise mitigation proposals.

Limit Level

1.  Identify the source.

2.  Notify CAPCOER, EPD and the Contractor.

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 CAPCOER and EPD the causes & actions taken for the exceedances.

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

8.  If exceedance stops, cease additional monitoring

1. Confirm receipt of notification of exceedance in writing.

2. Notify the Contractor.

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

4. Ensure remedial measures are properly implemented.

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

1. Take immediate action to avoid further exceedance.

2. Submit proposals for remedial actions to CAPCOthe ER within 3 working days of notification.

3. Implement the agreed proposals.

4. Resubmit proposals if problem still not under control.

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

Notes:

(a)   CAPCOER = Engineering representative of CAPCO

 

Table 3.3h     Event/ / Action Plan for Operational Noise

 

Action

Event

ET Leader

CAPCO

Action Level

1.  Identify source.

2.  Notify EPD and CAPCO

3.  Conduct additional noise monitoring and investigate the causes.

4.  Report the investigation results to the EPD and CAPCO.

5.  If the exceedance is related to the wind turbine, conduct additional monitoring for checking mitigation effectiveness and report the findings and results to EPD and CAPCO.

 

1.   Take immediate action to avoid further exceedance.

2.   Prepare proposal for remedial actions within 3 calendar days of notification.

3.   Implement the agreed remedial actions immediately.

Limit Level

1.  Identify source.

2.  Notify EPD and CAPCO.

3.  Analyse the performance of the wind turbine and the setting in order to investigate the causes of exceedance.

4.  Provide interim report to EPD and CAPCO the causes of the exceedances.

5.  If the exceedance is related to the wind turbine, assess effectiveness by additional monitoring.

6.  Report the remedial action implemented and the additional monitoring results to EPD and CAPCO.

7.  If exceedance stops, cease additional monitoring.

1.   Take immediate action to avoid further exceedance.

2.   Assist ET to analyse the performance of the wind turbine and the setting.

3.   Determine possible mitigation to be implemented and prepare proposal for remedial actions within 3 calendar days of notification.

4.   Implement the agreed remedial actions immediately.

6.  Prepare further proposal if the problems is still not under control.

 

3.3.7                                Mitigation Measures

Construction Phase

The contractor is required to adopt site specific direct technical measures as specified below for the enabling works along the Long Access Route near NSR N3.

·           Avoid or reduce concurrent operation of construction equipment;

·           Use of quiet construction plant;

·           Use of site hoarding barriers with a minimum height of 3m.  In general, this would provide a minimum 10 dB(A) attenuation for the low-rise receivers.  The barriers should not have openings or gaps and have a superficial surface density of at least 10 kgm-2.  The location and extent of the proposed barrier are shown in Figure 3.3a;

·           As a last resort, indirect mitigation measures in the form of window insulation and air-conditioning (air-conditioners have been provided for the staff quarters) are recommended to mitigate the residual noise impact.  In general, this would provide a minimum 10 dB(A) attenuation for the receivers. 

·           After consultation with CSD, agreed mitigation measures would be implemented (eg the use of air-conditioners and avoidance of use of the affected staff quarter during the period when works are undertaking in the area).  The Contractor will closely liaise with the CSD to programme the noisy construction works such that the noise impact to the CSD staff will be avoided or reduced.  Prior to commencement of the construction, CSD will be notified with the programme of the works, the planned construction activities, the potential impacts to the Staff Quarters, the measures to mitigate the impacts, the monitoring programme to check the efficiency of the measures, and the communication channels between CSD and the Site Engineer.

Operation Phase

Noise reduction methods for wind turbines include special finishing of gear teeth, using low speed cooling fans and adding baffles and acoustic insulation to the nacelle.  The detailed methods to be employed vary from supplier to supplier.  It is practicable and achievable to reduce the wind turbine with typical sound power level to 104 dB(A) during the detailed design stage of the wind turbine.  The tender specification of the Project will specify that the wind turbine will have a maximum operational noise level of 104 dB(A) with no tonality, impulsiveness and intermittency characteristics.

The noise assessment indicates that under the worst-case scenario (covering a full range of operation including start-up, shut-down, cut-in, cut-out, braking and yawing; and the full range of wind speeds), with a wind turbine with typical sound power level of 104 dB(A) and with no tone, impulse and intermittence characteristics, the predicted facade noise levels at the identified NSRs will comply with the day-time and night-time noise limits at all NSRs.

3.3.8                      Site Audit/Inspection

Monthly site audits/inspections will be conducted to ensure that the proposed mitigation measures are implemented properly and that the plant inventory used on site is consistent with the assumptions used in the EIA Report.