4. NOISE
4.1
Introduction
4.1.1 Based upon
the EIA Report, EM&A is recommended during both the construction and
operational phases to ensure the noise levels are reduced to acceptable levels,
to verify the traffic noise modelling and to ensure the effectiveness of the
traffic noise mitigation measures. Operational monitoring will be undertaken
within the first year of the operation of the road which forms the period of
the Contractor’s maintenance period. Thus, the Contractor and the Environmental
Specialist (ES) (see Section1) will be
responsible for the monitoring during this stage as an extension of the
construction phase EM&A.
4.2 INoise Parameters
4.2.1 The
construction noise level shall be monitored by the ES and 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. In respect of all other time periods, Leq(5
min) shall be employed for comparison with the Noise Control Ordinance
criteria.
4.2.2 As
supplementary information for data auditing, statistical results such as L10
and L90 shall also be obtained for reference and shall be recorded
by the ES. A sample data record sheet
is shown in Figure 4.1 for reference.
4.2.3 During
operational monitoring, traffic noise level shall be measured in terms of L10(1hour)
dB(A) during periods of peak traffic flows. Other information such as traffic flow counts, percentage of
heavy vehicles (all vehicles with unladen weight exceeding 1525kg) and average
speed shall also be obtained during the measurement period.
4.3 Monitoring Equipment
4.3.1 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.
4.3.2 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 1.0dB.
4.3.3 Noise
measurements shall not be made in fog, rain, wind with a steady speed exceeding
5m/s or wind with gusts exceeding 10m/s. The wind speed shall be checked with a
portable wind speed meter capable of measuring the wind speed in m/s.
4.3.4 The
Contractor shall ensure that sufficient noise measuring equipment and
associated instrumentation are available for carrying out the baseline
monitoring, construction phase impact monitoring and ad hoc monitoring. All the
equipment and associated instrumentation shall be clearly labelled.
4.4 Monitoring Locations
4.4.1 The
representative noise monitoring stations/sensitive receivers are shown in
Figures 4.2a-e. If the status or
locations of noise sensitive receivers change after issuing this manual, the ES
shall propose the updated monitoring locations and seek approval from the
Engineer’s Representative (ER) and agreement from the Independent Checker
(Environmental) (IC(E)) and Environmental Protection Department (DEP) of the
proposal to amend the monitoring locations.
4.4.2 When alternative
monitoring locations are proposed, the monitoring locations shall be chosen
based on the following criteria:
(i) monitoring at sensitive receivers close
to the major site activities which are likely to have noise impacts;
(ii) monitoring at the noise sensitive
receivers as defined in the Technical Memorandum; and
(iii) assurance of minimal disturbance to the
occupants during monitoring.
4.4.3 The
monitoring station shall normally be at a point 1m from the exterior of the
sensitive receivers building facade and, in the case the measurement is not
being carried out at a building, 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.
4.4.4 For
reference, a correction of +3dB(A) shall be made to the free field
measurements. Noise levels shall be
corrected in accordance with Section 2.10, 2.11 and 2.13 of the “Technical
Memorandum on Noise From Construction Works Other Than Percussive Piling”. The ES shall agree with the IC(E) on the
monitoring position and the corrections adopted prior to the commencement of
the works.
4.4.5 Once the
positions for the monitoring stations are chosen, the baseline monitoring and
the construction phase impact monitoring shall be carried out at the same
positions.
4.4.6
The Contractor shall establish the construction equipment list and
construction schedule which shall be checked and approved by the ER and agreed
by the IC(E). The timing of the noise
impact monitoring work shall be developed by the ES based upon the construction
schedule prepared by the Contractor.
The monitoring programme shall be approved by the ER, the IC(E) and the
DEP and shall be reviewed on a regular basis in light of any changes to the
Contractor’s construction schedule.
4.5 Baseline Monitoring
4.5.1 The ES shall
carry out baseline noise measurements at each monitoring stations shown in
Figures 4.2a-e prior to the commencement of the construction work over a 24
hour period. The baseline monitoring
shall be carried out daily for a period of at least two weeks and shall be
undertaken no earlier than three weeks prior to construction works being
carried out.
4.5.2 In no
circumstance should construction works be carried out within the range of the
monitoring stations during the two weeks of baseline monitoring.
4.5.3
Before commencing the baseline monitoring, the ES shall submit the
monitoring schedule to the ER for approval.
The IC(E) shall also be informed of the baseline monitoring programme
such that the IC(E) can conduct on-site audits to ensure the accuracy of the
monitoring results.
4.5.4 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.
4.6 Construction Phase Impact Monitoring
4.6.1 Noise
monitoring shall be carried out at each of the designated monitoring stations
directly affected by the construction works once every 6 days after the
commencement of construction.
4.6.2 During
construction works between 0700-1900 hours, one set of Leq(30 mins) measurements on normal weekdays shall be
taken. If construction works are extended to include works during the hours of
1900-0700, additional weekly impact monitoring comprising 3 consecutive Leq(5
mins) shall be carried out during evening and nighttime works and
applicable permits shall be obtained by the Contractor in accordance with the
NCO.
4.6.3 In case of
non-compliance with the construction noise criteria, more frequent monitoring
as specified in the Action Plan in Table 4.2 shall be carried out. This
additional monitoring shall be continued until the recorded noise levels are
rectified or proved to be unrelated to the construction activities.
4.7 Operational Monitoring
4.7.1 Locations for
operational noise monitoring have been selected on the basis that without the
noise mitigation they would exceed the criteria and are considered to be
representative of adjacent properties or particularly sensitive uses.
Representative locations for traffic noise monitoring are given below and are
shown in Figures 4.3:
¨
bottom floor of SR4B;
¨
third (top) floor of SR4; and
¨
third floor (top) of SR4D.
4.7.2 Noise
monitoring is recommended during the operational phase to ensure and confirm
that the noise attenuation of the recommended direct noise mitigation measures
meets the requirements of the EIA.
Monitoring shall be conducted on any three occasions for a 30 minute
period during the week day peak hours within the first year of the operation of
the road. The exercise shall be
repeated twice during months 6 and 12 of the commission year.
4.7.3 The status
and the locations of noise sensitive receivers may change after issuing this
manual. If such a situation occurs, the
ES shall propose updated monitoring locations and seek approval from the IC(E)
and the DEP. The alternative
monitoring point should be selected at a point which has nearly the same noise
exposure characteristic as the original location.
4.7.4
The ES shall be responsible for the liaison with IC(E) on all
environmental performance matters during the operational phase and timely
submission of all relevant EM&A proforma (see Appendix B) for IC(E)’s
approval.
4.7.4
4.7.5
During the operational phase, three noise measurements, each for
30 minutes, shall be carried out by the ES at each of the selected
representative noise monitoring locations during peak hours (namely, 08:00 to
09:30 and 17:30 to 18:00), in order to avoid a situation in which the flow is
too low to enable a fair comparison.
4.7.5
4.7.6
Measured noise levels should be compared with the predicted noise
levels using the counted traffic data at the time of measurement. The ES shall comment on the discrepancies,
if any, and report to the DEP for reference.
4.7.6
4.7.7
No Event and Action Plan is applicable to the traffic noise
monitoring during the operational phase.
4.7.7
4.8 Event and
Action Plan for Construction Noise
4.8.1 The Action
and Limit levels for construction noise are defined in Table 4.1. Should non-compliance
of the criteria occur, the ES, the IC(E), the ER and the Contractor shall
undertake their specified actions in accordance with the Action Plan shown in
Table 4.2.
Table 4.1 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)
|
* reduce to 70 dB(A) for schools and
65 dB(A) during school examination periods.
4.9 Noise Mitigation Measures
4.9.1 Background
4.9.1.1 The EIA report
has recommended noise control and mitigation measures to reduce noise levels
from Project construction and operation. The recommended mitigation measures
during construction and operational phase are summarised Appendix A and detailed
below. The Contractor shall be
responsible for the design and implementation of the construction measures and
for the construction of the operational measures in accordance with the
detailed design.
4.9.2 Construction Mitigation
4.9.2.1 The following
measures are
recommended at SRs 2, 4, 5, 9, 13-16 during road and bridge construction and SR
2 and 4 in Tung Chung Valley during permanent noise barrier construction as
detailed in Tables 4.3 and 4.4 respectively. The noise mitigation measures and
the sound reduction estimated are based on current noise control technologies
and BS5228 and have been confirmed by the Project Proponent as being practical.
Table 4.3: Recommended Mitigation Measures for the
Noisy Equipment during Road Construction and Bridge Construction
|
Plant
|
|
Noise Reduction, dB(A)*
|
Reduction Assumed, dB(A)
|
|
· Breaker
(Excavator Mounted)
|
¨ Fit
suitably designed muffler or sound reduction equipment.
¨ Use
dampened bit to eliminate ringing
|
Up to 15
|
5
|
|
· Excavator
· Bulldozer
· Concrete
Lorry Mixer
|
¨ Fit
more efficient exhaust sound reduction equipment
¨ Manufacturers’
enclosure panels should be kept closed
|
5 to 10
|
5
|
|
· Chipper
|
¨ Fit
suitably designed muffler or sound reduction equipment.
¨ Ensure
all leaks in air line are sealed
¨ Use
dampened bit to eliminate ringing
|
Up to 15
|
5
|
* Ref: Noise
and vibration control on construction and open sites, BS5228: Part 1: 1997,
P.15-16.
Table 4.4 Recommended
Mitigation Measures for the Noisy Equipment during Permanent Noise Barrier
Construction
|
Plant
|
|
Noise Reduction, dB(A)*
|
Reduction Assumed, dB(A)
|
|
·
Excavator
·
Crane
·
Lorry
·
Concrete Lorry Mixer
|
¨ Fit
more efficient exhaust sound reduction equipment
¨ Manufacturers’
enclosure panels should be kept closed
|
5 to 10
|
5
|
|
·
Poker
|
¨ Fit
suitably designed muffler or sound reduction equipment.
¨ Ensure
all leaks in air line are sealed
¨ Use
dampened bit to eliminate ringing.
|
Up to 15
|
5
|
* Reference:
Noise and vibration control on construction and open sites, BS5228: Part 1:
1997, P.15-16.
4.9.2.2 Temporary noise barriers are
also required at SR4, SR13 and SR15 during road construction, and SR2 and SR4
during permanent noise barrier construction in Tung Chung, such that the stationary
construction equipment will be totally screened
providing a 10 dB(A) attenuation and a 5dB(A) attenuation provided for moving
equipment. The design of the temporary noise barriers will be the
responsibility of the Contractor who will be required to submit his design to
the ER for approval before carrying out the work.
4.9.2.3 In addition
to the above, the number of excavator mounted breakers in operation during road
construction works at any one time should be restricted from two to only one
breaker in Tung Chung (SR 4) and the Cheung Sha area (SRs 13 and 15). Further mitigation
measure for SR13 is required during the construction scenario E1, E3, R1 and P2
at South Lantau Road. Restriction on
the time of operation of power mechanical equipment is, therefore, required. When the operation time of the breaker, dump
truck, bulldozer and grader is restricted by 50%, the predicted noise level
would be 75dB(A) during scenarios E1, E3, R1 and P2 and no exceedance would
occur.
4.9.2.4 In addition,
noise levels can be further controlled with the following standard noise
pollution control contract clauses:
¨
good site practice to limit noise
emissions at source;
¨
avoidance of simultaneous noisy
activities;
¨
reduction in the numbers of plant
operating in critical areas close to NSRs;
¨
use of a quiet equipment and
maintenance of it so as to minimise noise; and
¨
proper planning of work area.
4.9.3.4 Construction works for the permanent noise barrier in Tung Chung shall
be scheduled to avoid times when the mobile
crane and road planer for the road works and mobile crane for the site
development works associated with the Tung Chung Valley development are
on-going.
4.9.3.5 If the above
measures are not sufficient to restore the construction noise quality to an
acceptable level, upon the advice of ES, the Contractor shall consult the
IC(E), liaise and gain approval from the ER on other mitigation measures proposed to reduce noise
levels to an acceptable level and carry out these measures. The measures may include but not be limited
to amendments to the construction schedule to restrict noisy equipment to
certain time periods and restricting the type of equipment that can be used
during construction at any one time.
4.9.3 Operational Phase
4.9.3.1 A series of
noise structures in the form of barriers are required for the protection of
existing NSRs from operational traffic noise in Tung Chung. The barriers are given in Table 4.5 below.
Table 4.5 Summary of Direct Mitigation Measures
|
Barrier Height
|
Location of Barrier
|
Length of Barrier
|
Barrier Type
|
|
4.5m
|
Lung
Tseng Tau
|
30m
|
Reflective
|
|
1.5m
to 4.5m barrier (graded height)
|
Lung
Tseng Tau
|
59m
|
Reflective
|
|
1.5m
barrier
|
Lung
Tseng Tau
|
38m
|
Reflective
|
4.9.3.2 In addition, measures are
required to protect future receivers in both Tung Chung and Cheung Sha. For the future sale sites at Cheung Sha, a 2
meter high landscaped bund, together with a 4m
non building area along the boundary of the sites facing the new Tung Chung
Road is required. For the future school
in Area 40 of the Tung Chung Valley development, a 4m landscaped bund is
required to protect the school.
