The
principal legislation relating to the control of construction noise is the Environmental Impact Assessment Ordinance
(EIAO) (Cap. 499). The Technical Memorandum on Environmental Impact
Assessment Process (EIAO-TM), issued under the EIAO, provides guidelines and noise
criteria for evaluating noise impacts.
The assessment criteria are defined in Annex 5 of the EIAO-TM
with reference made to Annex 13 of
the EIAO-TM for the guidelines of
noise assessment.
The
Noise Control Ordinance (NCO) (Cap.
400) also provides statutory controls on general construction works during
restricted hours (i.e. 1900 to 0700 hours Monday to Saturday and at any time on
Sundays and public holidays). A number
of Technical Memoranda (TMs) have been issued under the NCO to stipulate noise control approaches and criteria. The Technical
Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM),
which provides the guidelines for controlling the construction noise from the
use of Powered Mechanical Equipment (PME) at the construction work sites,
details the procedures that should be adopted for the assessment of noise from
construction work other than percussive piling, the issuing of Construction
Noise Permits (CNP), and for determining whether or not any such CNP is being
complied with.
Under the EIAO,
the potential noise impact arising from general construction works during
normal working hours (i.e. 0700 to 1900 hours on any day not being a Sunday or
public holiday) at noise sensitive receivers that rely on opened windows for
ventilation, should be assessed in accordance with the noise criteria specified
in the EIAO-TM. The EIAO-TM
noise standards are presented in Table 4.1.
Table 4.1 EIAO-TM Daytime Construction Noise Standards (Leq,
30 min dB(A))
|
Uses |
Noise Standards (dB(A)) |
|
Domestic
Premises |
75 |
|
Educational
Institutions |
70 |
|
Educational
Institutions (during examination periods) |
65 |
|
Notes: (a)
The above standards apply to uses which rely on opened windows
for ventilation. (b)
The above standards shall be viewed as the maximum permissible
noise levels assessed at 1m from the external façade. |
|
It
is anticipated that no works are planned during restricted hours (i.e. 1900 to
0700 hrs of the next day and any time on Sundays and public holidays) at this
stage, CNP will be applied if any works will be carried out during restricted
hours. When assessing a CNP application
for the use of PME during the restricted hours (i.e. 1900 to 0700 hours of the
next day and any time on Sundays and public holidays), the Noise Control
Authority will compare the Acceptable Noise Levels (ANLs), as promulgated in GW-TM,
and the Corrected Noise Levels (CNLs) (i.e. after accounting for factors such
as barrier effects and reflections) associated with the proposed PME operations. The ANLs are related to the noise sensitivity
of the area in question and different Area Sensitivity Ratings (ASRs) have been
established to reflect the background characteristics of different areas. The appropriate ASR for the Noise Sensitive
Receiver (NSR) is determined with reference to Table 4.2.
Table 4.2 Area Sensitivity Ratings (ASRs)
|
Types
of Area Containing NSR |
Degree to which NSR is
affected by Influencing Factor (IF) |
||
|
Not Affected |
Indirectly Affected |
Directly Affected |
|
|
Rural area, including |
A |
B |
B |
|
Low density residential area consisting of low-rise or isolated high-rise developments |
A |
B |
C |
|
Urban area |
B |
C |
C |
|
Area other than those above |
B |
B |
C |
|
Notes: The
following definitions apply: (a)
" (b)
"Directly
affected" means that the NSR is at such a location that noise generated
by the IF is readily noticeable at the NSR and is a dominant feature of the
noise climate of the NSR; (c)
"Indirectly affected" means
that the NSR is at such a location that noise generated by the IF, whilst
noticeable at the NSR, is not a dominant feature of the noise climate of the
NSR; (d)
"Not affected" means that
the NSR is at such a location that noise generated by the IF is not
noticeable at the NSR; and (e)
"Urban area" means an area
of high density, diverse development including a mixture of such elements as
industrial activities, major trade or commercial activities and residential
premises. |
|||
The
relevant ANLs are shown in Table 4.3.
Table 4.3 Acceptable Noise Levels for General
Construction Works
|
Time
period |
LAeq 5min (dB(A)) |
||
|
|
ASR “A” |
ASR “B” |
ASR “C” |
|
All days during the evening (i.e. 1900-2300 hrs) and general holidays (including Sundays) during the day and evening (ie 0700-2300 hrs) |
60 |
65 |
70 |
|
All days during the night-time (i.e. 2300-0700 hrs of the next day) |
45 |
50 |
55 |
The Noise Control Authority will
consider a well-justified CNP application, for construction works within
restricted hours as guided by the relevant TMs issued under the NCO. The Noise Control Authority will take into
account the adjoining land uses and any previous complaints against
construction activities at the site before making a decision. Nothing in this EIA Report shall bind the
Noise Control Authority in making its decision.
The Noise Control Authority may include any conditions in a CNP that it
considers appropriate. Failure to comply
with any such conditions may lead to cancellation of the CNP and prosecution
action under the NCO.
There is no
specific requirements and noise criteria under the NCO and EIAO-TM for
evaluating noise impact due to marine traffic.
The Technical Memorandum on
Noise From Places Other than Domestic Premises, Public Places or Construction
Sites (IND-TM) issued under the NCO
specifies the applicable ANLs for assessing potential operation noise
impacts. The ANLs are dependent on the
ASR and the time of the day and are presented in Table 4.4.
Table 4.4 Acceptable Noise Levels for Operational Noise
|
Time
Period |
LAeq 30min (dB(A)) |
||
|
ASR “A” |
ASR “B” |
ASR “C” |
|
|
Daytime:
0700-1900 hrs & Evening: 1900-2300 hrs |
60 |
65 |
70 |
|
Night-time:
2300 hrs - 0700 hrs of the next day |
50 |
55 |
60 |
Fixed plant noise is controlled under Section 13 of the NCO and the
predictions will be undertaken in accordance with the IND-TM. The noise criteria for planning and design of
Designated Projects are set out in Table 1A of Annex 5 of the EIAO-TM as follows:
n
The noise level at the facade of the nearest NSR is at
least 5 dB(A) below the appropriate ANL (as shown in Table 4.4) as specified in the IND-TM; or
n
The prevailing background noise level (for quiet areas
with a noise level 5 dB(A) below the appropriate ANL).
Where
the Project is located in rural areas and no influencing factors affect the
NSRs, an ASR of “A” is assigned. Baseline noise
measurements have been conducted to investigate the prevailing noise levels and
to establish the noise limits for the assessment of the operational noise
impacts. Details of the noise
measurements for the Project are discussed further in Section 4.3.4.
The ASR assumed in this EIA Report is for an indicative
operation noise assessment only. It
should be noted that fixed noise sources are controlled under Section 13 of the NCO. At the time of
investigation, the Noise Control Authority shall determine noise impact from
concerned fixed noise sources on the basis of prevailing legislation and
practices being in force, and taking account of contemporary conditions /
situations of adjoining land uses.
Nothing in this EIA Report
shall bind the Noise Control Authority in the context of law enforcement
against any fixed noise source being assessed.
In accordance with the requirements
given in Clause 3.4.4.2 and Appendix C of the EIA Study Brief, the
Assessment Area for the noise impact assessment should generally cover a
distance of 300m from the boundary of the Project, and should be expanded to
include NSRs at distances over 300m from the Project which may be affected by
the Project. The Assessment Area
considered in the assessment is shown in Figure
4.1.
The new OCGTs are located at
LPS on the Lamma Island. Lamma Island is
rural in nature and surrounded by natural terrain. To the south of LPS is open sea. Background noise at the Project site and the
surround environment is dominated by the prevailing general background
including sea waves and operation of the existing power station.
The
statutory Outline Zoning Plans (OZP)
and other relevant development plan available from Lands
Department or Town Planning Board have been reviewed with regard to the
Assessment Area. The Assessment Area is located within the
boundary of the existing LPS, covered by the approved Lamma Outline Zoning Plan S/I-LI/11 under zoning ‘Other Specified
Uses – For “Power Station” only’. There
is no existing or planned NSR identified within the 300m Assessment Area from
the boundary of the Project. The first
layer of NSR is at least 800m away from the Project site.
A site
visit was carried out on 14 December 2020 to review the current situation for
the first layer of existing NSRs near the LPS.
Representative NSRs are identified and listed in Table 4.5 and shown in Figure 4.1. Photographs of the identified NSRs and the
existing building structures of LPS are shown in Appendix 4A.
Table
4.5 Identified Representative NSRs
|
NSR
ID |
Description |
Use |
Approximate
Distance to nearest Project Site Boundary (m) |
|
N1 |
Village House at Tai Shan
Central at Lamma Island |
Existing Residential |
810 |
|
N2 |
Village House at Hung Shing
Yeh |
Existing Residential |
1,450 |
N1 - Village House at Tai Shan Central at Lamma Island
The Village House at Tai Shan Central at Lamma
Island (NSR N1) is located approximately 810m to the northeast of the Project
site. The direct line of sight of NSR N1
to the Project site is totally screened by the existing building structures of
LPS and natural terrain (see Figure
4.2).
For NSR N1, the separation distance between the
Project site and NSR N1 is about 810m, and they are screened by the natural
terrain and existing building structures of LPS. Hence, unacceptable noise impact due to the
Project is not anticipated. Based on
this, quantitative noise impact assessment is considered not necessary at NSR
N1.
N2 - Village House in Hung Shing Yeh at Lamma
Island
The Village House at Hung Shing
Yeh (NSR N2) is approximately 1.45km to the east of the Project site. NSR N2 is located at high level, just above
the top of the small hill viewing to the west towards the LPS, and hence it is
considered as a NSR that may be affected by the operation of the Project.
Summary
Despite the large separation distance of 1.45km, in
view of the background noise environment at NSR N2 being typically rural in
nature, and that there is only partial screening from the existing plant
buildings and structures of the LPS, NSR N2 is considered as the critical NSR
to the Project site. Fixed plant noise
due to the operation of the Project may have potential noise impact to this
NSR. Based on the above, NSR N2 is
identified as the representative NSR for quantitative operational noise impact
assessment to present the worst case scenario for the Project.
Noise measurements were taken at the
Concerto Inn near NSR N2 on 14 – 15 December 2020 and 28 – 29 May 2021 to
investigate the prevailing background noise levels. Due to close proximity between Concerto Inn
and NSR N2, the background noise environment is considered similar at both
locations. The noise measurements were
conducted using a Rion NL-52 Sound Level Meter (Type 1), which had been
calibrated using a 01dB-Stell CAL21 Sound Calibrator with a calibration signal
of 94.0 dB(A) at 1kHz. The microphone
was set at 1.2m above floor level with façade reflection. The measurements were conducted in accordance
with the calibration and measurement procedures stated in the IND-TM.
Two (2) sets of 30-minute baseline noise measurement
have been conducted at NSR N2 during each of the daytime and evening periods (i.e.
2200 – 2300 hrs within 0700 – 2300 hrs), and night-time period (i.e. 0200 –
0300 hrs within 2300 – 0700 hrs of the next day) on two different
weekdays. The two aforementioned
background noise measurement periods (i.e. 2200 – 2300 hrs and 0200 – 0300 hrs
of the next day) are considered to be representative to reflect the minimum
background noise levels of the respective daytime/evening and night-time
periods. Averaged L90 has
been adopted as prevailing background noise levels.
The measurement location is shown
in Figure 4.3 with measured
prevailing background noise levels summarised in Table 4.6 with details
shown in Appendix 4B.
Table
4.6 Measured Prevailing Background Noise
Levels
|
Location |
Time Periods |
Averaged Measured Noise Levels (Measured Noise
Levels), L90 (30min) dB(A) (b) |
ANL-5 for ASR
“A”, dB(A) (a) |
Operational Noise Criteria, dB(A) (a) |
|
Concerto
Inn |
Daytime
& Evening |
53 |
55 |
53 |
|
Night-time |
52
|
45 |
45 |
|
|
Notes: (a) IND-TM specifies the
applicable Acceptable Noise Levels (ANLs) for the
operation of the Project. The noise criteria for planning and
design of Designated Projects are set out in the EIAO-TM as follows: -
the noise level at the facade of the nearest NSR is
at least 5 dB(A) below the appropriate ANL (as shown in Table 4.4) as specified
in the IND-TM; or, -
the prevailing background noise level (for quiet
areas with a noise level 5 dB(A) below the appropriate ANL). (b) The
background noise is mainly dominated by the sound of sea waves. |
||||
Potential
noise sources during the demolition and construction phases of the Project will
mainly arise from Powered Mechanical Equipment (PME) operating at the Project
site. The works carried out on-site are
expected to be relatively small-scale and noisy activities, i.e. extensive
concrete breaking and foundation works are not required. Major components of the Project will be fully
assembled off-site as far as practicable to minimise assembly works to be
carried on-site. The major works will
include:
n Decommissioning
and removal of the existing OCGTs and CCGT, including GT2, GT3, GT4, GT57 and
GT6; and
n Installation
of new OCGTs, including GT8, GT9, GT10 and GT11, and associated facilities.
There may be potential marine
traffic noise impact from delivery of construction equipment and components of
the new OCGTs via marine route to the LPS jetty. Waste generated during the demolition and
construction phases may also be transported off-site via marine route to the fill
banks or landfills for reuse or disposal.
As the demolition and construction works associated with the Project are
small scale, marine traffic for equipment transport and waste disposal during
the demolition and construction phases of the Project are expected to be limited,
i.e. no more than 1 to 2 marine vessel trips within every 2 days during daytime
period only. There will be no marine
traffic associated with the demolition and construction of the Project during
night-time period.
Fixed plant
noise associated with the operation of the new OCGTs, including GT8, GT9, GT10
and GT11, is the major potential noise source during operation phase of the
Project. The new OCGTs would only be
operated intermittently during peak-lopping and emergency situations. However, the
operation of the new OCGTs could occur any time of a day from Monday to Sunday,
including public holidays.
No existing
or planned NSR was identified within 300m distance from the Project site
boundary. All NSRs are located far away
from the Project site (at least 810m) and noisy activities (i.e. extensive
concrete breaking and foundation works) are not required. Therefore, adverse noise impact during
demolition and construction phases are not anticipated and quantitative noise
assessment is considered not necessary.
No existing
or planned NSR was identified within 300m distance from the Project site
boundary. All NSRs are located far away
from the LPS jetty (at least 1.6km) and further away from the marine vessel
route. With no more than 1 to 2 vessel
trips within every 2 days, adverse noise impact due to marine traffic during
demolition and construction phases are not anticipated and quantitative marine
traffic noise assessment is considered not necessary.
No NSR was identified within the 300m distance
from the Project site boundary. The nearest NSR
N1 is located at approximately 810m from the Project site boundary with no
direct line of sight to the OCGTs due to screening by the existing building
structures of the LPS and natural terrain.
Hence, noise impact due to operational activities of the Project is not
anticipated at NSR N1. However, with the
background noise environment typically rural in nature, the operational noise
criteria are more stringent. NSR N2 is
approximately 1.45km away from the Project site, with partial screening from
the existing plant buildings and structures of the LPS. As a conservative assessment, a quantitative
noise assessment has been carried out for the operation of the OCGTs at NSR N2,
which is the nearest NSR with possible direct line of sight towards the
OCGTs. With reference to the discussion
in Section
4.3.3, a quantitative operational noise assessment for the other NSRs
is considered not necessary.
The fixed plant noise sources from the OCGTs are
identified as the major noise sources from the Project which may cause noise
impact to NSR N2. The worst case
operation mode which represents the maximum noise emission in connection with
the identified fixed noise sources of the operation of the OCGTs has been
assessed.
The methodology used for the quantitative
fixed plant noise assessment is in accordance with the procedures outlined in
the IND-TM and the EIAO-TM and is presented
below:
n Identify
the types of equipment and their number;
n Calculate the
maximum total SWL from the OCGTs;
n Identify
representative NSR as defined by the EIAO-TM based on existing
and committed land uses that may be affected by the OCGTs;
n Calculate the
distance correction factors, using a conservative approach, based on the
horizontal distance between the NSR and the noise sources;
n Calculate the
corrected noise levels after taking into account other corrections such as
potential screening effects, if any, by adopting standard acoustics principles,
and atmospheric absorption in accordance with ISO 9613-1 Acoustics – Attenuation of Sound During Propagation Outdoors
– Part 1: Calculation of the Absorption of Sound by the Atmosphere; and
n Present the
results in terms of Leq, 30min dB(A), as specified in the IND-TM.
The predicted noise levels at the NSR N2 (see Section
4.6.2) were compared with the criteria set out in Table
4.6.
As advised by HK Electric, the maximum sound
power level (SWL) of each new set of OCGT (including gas turbine, generator,
transformer, intake and exhaust) shall be 104dB(A). Such sound power level requirement shall be included
in the HK Electric’s Contract Specification for this Project. Therefore, such sound power level requirement
has been adopted in the quantitative operational noise assessment for the OCGTs as presented
in Appendix 4C. As
the OCGTs may operate any time of a day, noise impact due to operation of the
OCGTs during daytime/ evening period and night-time period has been assessed.
As no NSRs were identified
within 300m from the Project site boundary and that the nearest representative
NSR with possible direct line of sight is located approximately 1.45km away
from the Project site, adverse noise impact due to the demolition
and construction activities is not anticipated.
The predicted noise levels at
the representative NSR N2 due to operation of the OCGTs are summarised in Table
4.7. Detailed calculation of predicted noise
levels are presented in Appendix
4D.
Table
4.7 Predicted Noise Level at the
Representative NSR N2
|
NSR ID |
Predicted Noise Level, dB(A) |
Noise Criteria, dB(A) (b) |
Compliance (Yes/No) |
|||
|
|
D (a) |
N (a) |
D |
N |
D |
N |
|
N2 |
37 |
37 |
53 |
45 |
Yes |
Yes |
|
Notes: (a) D: Daytime and Evening, 0700-2300 hours,
N: Night, 2300-0700 hours. (b) Please refer to Table 4.6. |
||||||
Based on the plant inventory
presented in Appendix 4C,
results of the quantitative noise assessment due to operation of the OCGTs
indicate that the predicted noise levels at 1m from
the façade of the NSR N2 comply with the respective noise criteria during
daytime and night-time periods. Therefore, adverse noise impact due to
operation of the OCGTs is not anticipated.
In view
of the insignificant noise impact arising from the Project, no mitigation
measures are required for the demolition and construction phases. However, the following good site practices
should be followed:
n Machines and
construction plant that may be in intermittent use should be shut down between
work periods or should be throttled down to a minimum; and
n Only
well-maintained construction plant should be operated on-site and should be
serviced regularly.
The
predicted noise levels based on a conservative quantitative assessment at the
representative NSR N2 due to the operation of the OCGTs are well below the
daytime and night time criteria as a result of the considerable separation
distance between NSR N2 and the OCGTs.
Therefore, no mitigation measures are required during the operation
phase.
At
present, the known projects that are existing, committed and planned to be
constructed and operated in the vicinity of the Project site have been
considered when assessing the cumulative noise impact. The projects that may pose cumulative noise
impact include the Hong Kong Offshore LNG
Terminal, 1,800 MW Gas-fired Power
Station at Lamma Extension, Lamma
Power Station – Unit L2 Flue Gas Desulphurization Plant Retrofit Project, Lamma
Power Station Units L4 & L5 Flue Gas Desulphurization Plant Retrofit
Project and Improvement Dredging for
Lamma Power Station Navigation Channel.
According
to the latest construction programme for
Hong Kong Offshore LNG Terminal, the construction of Gas Receiving Station
(GRS) at LPS will be completed tentatively by first quarter of 2022 before this
Project commences. Therefore, cumulative
noise impact from the Hong Kong Offshore LNG Terminal is not expected.
Unit L9 and L10 are currently under operation while L11 and L12 are
currently under construction at LPS. In
accordance with the EIA
Report for 1,800 MW Gas-fired Power
Station at Lamma Extension (AEIAR-010/1999), the predicted maximum noise
levels due to the construction works are 55dB(A) at NSR N1 and 62dB(A) at Hung
Shing Yeh near NSR N2, which are well below noise criterion of 75dB(A).
Improvement
dredging for the LPS navigation channel during construction phase is currently
ongoing. In accordance with the EIA for Improvement Dredging for Lamma Power
Station Navigation Channel (AEIAR-212/2017), the predicted maximum noise
levels due to construction of the project during daytime period are 67dB(A) and
64dB(A) at NSRs N1 and N2, respectively, which are also well below the
construction noise criterion of 75dB(A).
Adverse
cumulative noise impact from the abovementioned projects is not expected during
the demolition and construction phases of the Project.
In accordance with AEIAR-010/1999,
Lamma Power Station – Unit L2 Flue Gas
Desulphurization Plant Retrofit Project (DIR-153/2007) and Lamma Power Station Units L4 & L5 Flue
Gas Desulphurization Plant Retrofit Project (AEIAR-098/2006), the predicted
maximum noise levels at Hung Shing Ye near NSR N2 due to operation of existing
units at LPS and proposed units at LPS Extension Site are 55dB(A) in summer and
52dB(A)
in winter during daytime period, and 50dB(A) in both summer and winter during
night-time period.
In
accordance with the EIA Report for Hong Kong Offshore LNG Terminal (AEIAR-218/2018),
the predicted maximum noise level due to operation of the Gas Receiving Station
(GRS) at LPS is
44 dB(A) at NSR N2 during both daytime and night-time periods.
Therefore,
with a predicted noise level of 37dB(A) at NSR N2 as presented in Table
4.7, the
operation of the new OCGTs will have insignificant contribution to the
cumulative operational noise impact. Adverse cumulative noise impact arising from the
operation of the Project is not anticipated.
No adverse residual noise impact is anticipated from the demolition/ construction
or operation of the Project.
No
adverse noise impact is anticipated to arise from the demolition and
construction works of the Project and thus noise monitoring is considered not
necessary. However, it is recommended to
carry out regular environmental site inspections to ensure the implementation
of the good site practices as recommended in Section 4.7.1 throughout
the demolition and construction phases.
Adverse
noise impact is not anticipated during the operation of the Project. Environmental monitoring and audit related to
noise during the operation phase is considered not necessary.
No existing or planned NSR was
identified within 300m from the Project site boundary and representative NSRs
with possible direct line of sight to the Project is located at least 1.45km
away from the Project site. Therefore,
unacceptable noise impact associated with the demolition and construction of
the Project is not anticipated.
Predicted noise levels at NSR N2
due to the operation of the OCGTs indicated full compliance with the relevant
operational noise criteria during both daytime and night-time periods. Therefore, unacceptable noise impact arising
from the operation of the Project is not anticipated.
Mitigation measures are not
required in meeting the requirements of Section
6 of Annex 13 of the EIAO-TM.
Noise monitoring is also considered not necessary during both the demolition/
construction and operation phases of the Project.