2.1
In this section, the requirements,
methodology, equipment, monitoring locations, criteria and protocols for the
monitoring and audit of noise impacts during the construction phase of the Project
are presented.
2.2
The EIA study provided the maximum permissible sound power
levels (Max SWLs) of the identified fixed noise sources of the Project. The Max SWLs should be implemented and
refined by the Contractor. In order
to ensure the operational airborne noise levels would comply with the noise
standards as stipulated in the Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM), the Contractor
should carry out a noise commissioning test for all major fixed noise sources
before operation of the Project. A
summary of noise criteria for fixed plant noise sources is provided in Appendix B.
2.3
The construction
noise level 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 (15
minutes) shall be employed for comparison with the Noise Control
Ordinance (NCO) criteria.
2.4
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 C for reference.
2.5
Whilst the
Noise Control Ordinance (NCO) does not provide for the statutory control of
construction activities occurring on weekdays during normal working hours (i.e.
Monday to Saturday inclusive 0700-1900 hours), a daytime assessment criterion
of Leq(30 minute) 75dB stipulated in Annex 5 of the Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM) shall be
used as the appropriate assessment criterion for all residential dwellings;
while a daytime assessment standard of Leq(30 minute) 70dB will be
adopted for all educational institutions during normal school days and Leq
(30 minute) 65dB during examination periods.
2.6
The NCO
provides statutory controls on general construction works during restricted
hours (i.e. 1900-0700 hours Monday to Saturday and at any time on Sundays and
public holidays). The 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 2.1.
Table 2.1
Acceptable Noise Levels (ANLs)
Time Period |
Area Sensitivity Rating |
||
A |
B |
C |
|
All days during the evening (1900-2300 hours) and general
holidays (including Sundays) during the day and evening (0700-2300 hours) |
60 |
65 |
70 |
All days during the night-time (2300-0700) |
45 |
50 |
55 |
2.7
As referred to
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
levels from before and after the noise measurement agree to within 1.0 dB.
2.8
Noise
measurements should 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.
2.9
The 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.
2.10
Based on the
EIA study, twenty potentially worst affected locations are designated for
construction noise monitoring as listed in Table 2.2 and illustrated in Figure 2.1 to 2.7.
Table
2.2 Noise Monitoring Stations
during Construction Phase
Identification No. |
NSR ID in EIA Report |
Noise Monitoring Stations |
CN1 |
KET 15 |
Sisters of the Immaculate Heart of
Mary (Kongmoon) – Kit Sam Convent |
CN 2 |
KET 9 |
Hong Kong Institute of Vocation Education
(Tsing Yi) |
CN 3 |
KET 10 |
|
CN 4 |
KET 3 |
Luen Tak Apartments |
CN 5 |
UNI 1 |
|
CN 6 |
UNI 15 |
|
CN 7 |
UNI 7 |
The Bauhinia |
CN 8 |
UNI 10 |
|
CN 9 |
UNI 12 |
|
CN 10 |
UNI 13 |
Graceful Court |
CN 11 |
UNI 6 |
|
CN 12 |
UNI 18 |
|
CN 13 |
SYP 1 |
No. 18-20 Eastern Street |
CN 14 |
SYP 6 |
Bon-Point |
CN 15 |
SYP 8 |
|
CN 16 |
SYP 12 |
|
CN 17 |
SYP 14 |
|
CN 18 |
GT 2 |
|
CN 19 |
GT 4 |
Yu Hing Mansion |
CN 20 |
GT 5 |
Ka On Building |
CN 21 |
KET 13 |
The Merton (Block 2) |
2.11
The status
and location of noise sensitive receivers may change after issuing this
manual. If such cases exist, the ET Leader shall propose updated monitoring
locations and seek approval from the ER and agreement from the IEC and EPD on
the proposal. When alternative monitoring locations are proposed, the
monitoring locations shall be chosen based on the following criteria:
§
Monitoring at sensitive receivers
close to the major site activities which are likely to have noise impacts
§
Monitoring close to the noise
sensitive receivers as defined in the Technical Memorandum
§
Assurance of minimal disturbance to
the occupants during monitoring in the vicinity of sensitive receivers
2.12
The
monitoring station shall normally be at a point
2.13
The ET shall
carry out baseline noise monitoring prior to the commencement of the
construction works. The baseline monitoring shall be measured for a
continuous period of at least 14 consecutive days at a minimum logging interval
of 30 minutes for daytime (between 0700 and 1900 hours of normal weekdays) and
15 minutes (as three consecutive Leq, (5 minutes) readings) for evening time
(between 1900 and 2300 hours of normal weekdays), general holidays including
Sundays (between 0700 and 2300 hours) and night-time (between 2300 and 0700 of
all days). The Leq, L10 and L90 shall be recorded at the specified
interval. A schedule on the baseline monitoring shall be submitted to the
IEC for approval before the monitoring starts. The baseline noise
monitoring period shall cover the proposed operation hours of the Project.
2.14
There shall
not be any construction activities in the vicinity of the stations during the
baseline monitoring. Any non-project related construction activities in the
vicinity of the stations during the baseline monitoring shall be noted and the
source and location recorded.
2.15
In
exceptional cases, when insufficient baseline monitoring data or questionable
results are obtained, the ET Leader shall liaise with the IEC and EPD to agree
on an appropriate set of data to be used as a baseline reference.
2.16
Noise
monitoring shall be carried out at all the designated monitoring
stations. The monitoring frequency shall depend on the scale of the
construction activities. An initial guide on the monitoring is to obtain
one set of 30-minute measurement at each station between 0700 and 1900 hours on
normal weekdays at a frequency of once a week when construction activities are
underway.
2.17
Any General
construction work carried out during restricted hours is controlled by
Construction Noise Permit (CNP) under the NCO.
2.18
For school exists
near the construction activity, noise monitoring shall be carried out at the
monitoring stations for the schools during 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.
2.19
In case of
non-compliance with the construction noise criteria, more frequent monitoring,
as specified in Event / Action Plan in Table
2.4 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.
2.20
The Action and Limit levels for construction noise are
defined in Table 2.3. Should
non-compliance of the noise quality criteria occur, actions in accordance with
the Event and Action Plan in Table 2.4
shall be taken.
Table 2.3
Action and Limit Levels for Construction Noise
Time Period |
Action |
Limit |
0700-1900 hrs on normal weekdays |
When one documented complaint is
received |
75* dB(A) |
0700-2300 hrs on
holidays; and 1900-2300 hrs on all other days |
65/70 dB(A) # |
|
2300-0700 hrs of next
day |
50/55 dB(A)# |
* Limit for school is reduce to 70 dB(A) and 65 dB(A) during
school examination periods.
# Limit depends on Area Sensitivity Rating (ASR). The ASR for
monitoring locations is “B”, the
limit should be 65dB(A) and 50dB(A) for the period during 0700-2300 and
2300-0700 respectively. The ASR for monitoring locations is “C”, the limit
should be 70dB(A) and 55dB(A) for the period 0700-2300 and 2300-0700
respectively.
2.21
To account for cases where ambient noise levels as
identified by baseline monitoring approach or exceed the stipulated Limit
Levels prior to commencement of construction, a Maximum Acceptable Impact Level
may be defined and agreed with EPD, which incorporates the baseline noise
levels and the identified construction noise Limit Level. The amended level
will therefore be greater than 75 dB(A) and will represent the maximum
acceptable noise level at a specific monitoring station. Correction factors for
the effects of acoustic screening and/or architectural features of NSRs may
also be applied for as specified in the TM.
ACTION |
||||
ET |
IEC |
ER |
CONTRACTOR |
|
Action
Level |
1. Notify
IEC and ER 2. Carry
out investigation 3. Report
the results of investigation to the IEC and ER 4. Discuss
jointly with the ER and 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 ER with copy to 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, EPD the causes and
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, 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 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 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 ER with copy to IEC 3.Implement the
agreed proposals 4.Revise and
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 |
Table 2.4 Event and Action Plan for Construction Noise Monitoring
2.22
The EIA report indicated that construction activities would
cause noise exceedance at NSRs. Therefore, appropriate mitigation measures and
good site practices are recommended to be properly implemented. The Contractor
shall be responsible for the design and implementation for these measures.
2.23
The mitigation measures
recommended in the EIA report are summarized below:
§
Implementation of the following good
site practices:
-
only well-maintained plant shall be operated on-site and
plant shall be serviced regularly during the construction program;
-
silencers or mufflers on construction equipment shall be
utilized and shall be properly maintained during the construction program;
-
mobile plant, if any, shall be sited as far away from NSRs
as possible;
-
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;
-
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
-
material stockpiles and other structures shall be
effectively utilized, wherever practicable, in screening noise from on-site
construction activities.
§
Adoption of silenced types of PME, which
should be in accordance with BS 5228: Part 1, 1997, as proposed in the EIA
report
§
Use of movable noise barrier
§
Use of noise enclosure or acoustic
shed
§
Use of acoustic enclosure to cover
the rock drill
§
Use of noise insulating cover
§
Use of silencer
§
Use of noise insulating fabric
§
Use of “Noise Control Curtain” for
the demolition works at Ex-Police Quarter site
§
Use of temporary noise barrier
§
Decking over the excavation area or
lift shaft
§
Full enclosure of works areas
§
Use of alternative quieter construction method such
as concrete crusher
2.24
If the above measures are not sufficient to restore the
construction noise quality to acceptable levels upon the advice of ET Leader,
the Contractor shall liaise with the ET Leader on some other mitigation
measures, propose them to ER for approval, and carry out the mitigation
measures.
2.25
The implementation schedule for the recommended mitigation
measures is presented in Appendix A.