3.1
Potential airborne noise impacts likely to arise from the proposed Project
during both the construction and operation phases have been evaluated and the
results are presented in this section.
3.2
The following potential airborne noise impacts were assessed, and the predicted noise levels and necessary noise
mitigation measures
to control the impacts to within established criteria are presented in this section:
§
Construction noise
§
Operational phase fixed plant
noise
3.3
The Noise Control Ordinance (NCO) and Environmental Impact
Assessment Ordinance (EIAO) provide the statutory framework for noise
control. Assessment procedures and
standards are set out in the five Technical Memoranda (TMs) listed below:
§ TM on Environmental
Impact Assessment Process (EIAO-TM)
§ TM on Noise from
Construction Work other than Percussive Piling (GW-TM)
§ TM on Noise from
Percussive Piling (PP-TM)
§ TM on Noise form
Construction Work in Designated Areas (DA-TM)
§ TM on Noise from Places
other than Domestic Premises, Public Places or Construction Sites (IND-TM)
3.4
Potential construction noise and fixed plant noise impacts arising from
the Project have been assessed in accordance with the criteria and methodology
given in the TMs made under the NCO and the EIAO.
3.5
It is noted that
percussive piling is governed by the PP-TM and separate application to EPD for
Construction Noise Permit (CNP) would be required.
3.6
Daytime construction noise (excluding percussive piling) between the hours 0700 – 1900 on weekdays, i.e. non-restricted hours, is controlled under the EIAO. Annex 5 of the EIAO-TM sets out the
construction noise assessment limits, which are Leq(30 min) 75dB(A)
for domestic premises and Leq(30 min) 70dB(A) for schools during
normal hours (65dB(A) during examination periods) and all other places where
unaided voice communication is required.
3.7
Between 1900 and 0700 hours and all day on Sundays and
public holidays, activities involving the use of powered mechanical equipment
(PME) for the purpose of carrying out construction work is prohibited unless a
Construction Noise Permit (CNP) has been obtained. A CNP may be granted in cases where the noise
can be contained within the Acceptable Noise Level (ANL) at the NSRs. ANLs are assigned depending upon the Area
Sensitivity Ratings (ASRs). The
corresponding basic noise levels (BNLs) for evening and nighttime periods are
given in Table 3.1.
Table 3.1 Construction Noise Criteria for
Activity other than Percussive Piling
Time Period |
Basic Noise Level (BNLs) |
||
ASR A |
ASR B |
ASR C |
|
Evening (1900 to 2300
hours) (1) |
60 |
65 |
70 |
Night (2300 to 0700
hours) |
45 |
50 |
55 |
Notes: (1) Includes Sundays and Public Holidays
during daytime and evening
3.8
Despite any description or assessment made in this EIA
Report on construction noise aspects, there is no guarantee that a Construction
Noise Permit (CNP) will be issued for the project construction. The Noise
Control Authority will consider a well-justified CNP application, once filed,
for construction works within restricted hours as guided by the relevant
Technical Memoranda issued under the Noise Control Ordinance. The Noise Control
Authority will take into account contemporary conditions/ situations of
adjoining land uses and any previous complaints against construction activities
at the site before deciding whether to grant a CNP. Nothing in this EIA Report should bind the
Noise Control Authority in making its decision.
If a CNP is to be issued, the Noise Control Authority should include in
the permit any condition it thinks fit.
Failure to comply with any such conditions will lead to cancellation of
the CNP and prosecution under the NCO.
3.9
Under the TM on Noise from Construction Work in Designated
Areas, the use of five types of Specified Powered Mechanical Equipment (SPME)
and three types of Prescribed Construction Work (PCW) within a designated area
during restricted hours would require a valid CNP. The SPME includes hand-held breaker,
bulldozer, concrete lorry mixer, dump truck and hand-held vibratory poker. The PCW are:
·
Erecting or
dismantling of formwork or scaffolding.
·
Loading, unloading or
handling of rubble, wooden boards, steel bars, wood or scaffolding material.
·
Hammering.
3.10
In general, it should not be presumed that a CNP would be
granted for carrying out PCW within a designated area during restricted
hours. The CNP may be granted for the
execution of construction works during restricted hours involving the use of
PME and/ or SPME if the relevant Acceptable Noise Levels and criteria
stipulated in the GW-TM and DA-TM can be met.
3.11
As defined in the Noise Control Designated Area Plan, the
whole WIL alignment and works areas except Works Areas E and F are within the Designated Area.
3.12
According to the construction programme, all the proposed
construction works except
for underground tunnelling work and the temporary magazine site would be carried out during non-restricted hours. In case of
any construction activities during restricted hours, it is the Contractor’s
responsibility to ensure compliance with the NCO and the relevant TMs. The
Contractor will be required to submit CNP application to the Noise Control
Authority and abide by any conditions stated in the CNP, should one be issued.
3.13
There are no statutory procedures and criteria under the NCO
and EIAO for assessing the airborne noise impacts of blasting and are therefore
beyond the scope of the EIA. However,
the administrative and procedural control of all blasting operations in
3.14
The NCO and IND-TM control noise from fixed noise sources
such as ventilation shaft, chiller and cooling tower. For the assessment of impacts from fixed noise sources, the area sensitivity rating (ASR) of the noise sensitive receivers must be determined in accordance with the IND-TM,
and based on the ASR, the appropriate acceptable noise levels (ANL) can be
determined. ANL is shown in Table 3.2. For this assessment, the ASRs assumed for each NSR and the associated ANL are shown in Appendix 3.1.
Table 3.2 Acceptable Noise Level for Fixed Plant Noise
Time Period |
NCO criteria
|
TM-EIA |
||||
ASR ‘A’ |
ASR ‘B’ |
ASR ‘C’ |
ASR ‘A’ |
ASR ‘B’ |
ASR ‘C’ |
|
Daytime and Evening
(0700-2300 hours) |
60 |
65 |
70 |
55 |
60 |
65 |
Night-time (2300-0700
hours) |
50 |
55 |
60 |
45 |
50 |
55 |
Source: IND-TM
3.15
In any event, the Area Sensitivity Rating assumed in the EIA
Report is
only for indicative and it is
used for assessment only. It should be
noted that the fixed noise sources are controlled under section 13 of the
NCO. Therefore, 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 the EIA study shall bind the Noise
Control Authority in the context of law enforcement against any of the fixed
noise sources being assessed.
3.16
More stringent criteria for
assessing noise impacts of fixed plant are recommended in the EIAO-TM for
planning purposes. The recommended assessment
criteria are as follows:
§
Criteria (1) : 5dB(A) below the appropriate Acceptable Noise Levels (ANL)
set out in the IND-T
§
Criteria (2) : The prevailing background noise level where the prevailing
background noise level is 5dB(A) below the appropriate ANL (i.e. ANL – 5dB(A)).
3.17
Criteria (2) would be more
stringent than Criteria (1), and would generally apply to areas with low
ambient noise levels such as rural and suburban areas. The Project areas are located in well
developed urban areas of Hong Kong Island and as noted from site observations,
the prevailing background noise levels would unlikely be 5dB(A) lower than the appropriate ANL (i.e. Daytime 60 or 65dB(A) and Nighttime 50 or 55dB(A)). Thus, Criteria (1) have been adopted assessment criteria for the fixed plant noise impact assessment.
3.18
Representative NSRs within
3.19
According to Annex 13 of the EIAO-TM, NSRs include the
following:
§
Residential uses – all domestic premises including temporary
housing
§
Institutional uses – including educational institutions
§
Other uses such as hostels and country parks
3.20
In order to evaluate the
construction and operational noise impacts likely to arise from the Project,
representative NSRs (both existing and planned NSRs) were selected within the study area
(i.e. those at the most critical locations) according to the criteria set out
in the EIAO-TM, through site visits and a review of relevant land use
plans including the Outline Zoning Plan (Plan No. S/H1/14 and
S/H3/21).
3.21
NSRs located closest to the
subject noise sources, i.e. the first layer of NSR, would be considered as the
most critical locations and thus selected for noise assessment. Table 3.3 presents a summary of representative NSRs selected
for the present assessment. Locations
of representative NSRs are shown in Figure
3.1-3.13.
Table 3.3 Representative Noise Sensitive Receivers
Works
Area |
NSR |
Description |
Land Use |
Existing / Planned NSR |
No of storey |
Construction Noise Assessment |
Fixed Plant Noise
Assessment |
KET Station |
|||||||
C & D – |
KET 1 |
Kwun
Lung Lau (Block D) |
Residential |
Existing |
21 |
√ |
√ |
KET 2 |
Luen
Fat Apartments |
Residential |
Existing |
15 |
√ |
|
|
KET 3 |
Luen
Tak Apartments |
Residential |
Existing |
15 |
√ |
|
|
KET 4 |
|
Residential |
Existing |
27 |
√ |
|
|
KET 5 |
|
Residential |
Existing |
18 |
√ |
√ |
|
KET 6 |
|
Residential |
Existing |
37 |
√ |
√ |
|
KET 7 |
|
Residential |
Existing |
5 |
√ |
|
|
KET P1 |
Kwun Lung Lau |
Residential |
Planned |
- |
√ |
√ |
|
A – Ex-Police Quarter |
KET 9 |
Hong
Kong Institute of Vocation Education (Tsing Yi) |
School |
Existing |
7 |
√ |
√ |
B – Abattoir Site |
KET 10 |
|
School |
Existing |
7 |
√ |
|
KET 11 |
Cayman
Rise (Block 1) |
Residential |
Existing |
31 |
√ |
|
|
KET 12 |
|
Residential |
Existing |
22 |
√ |
|
|
KET 13 |
The
Merton (Block 2) |
Residential |
Existing |
45 |
√ |
|
|
KET 14 |
|
Clinic |
Existing |
3 |
√ |
|
|
MA – Under-ground Magazine Site |
KET 15 |
Sisters of the Immaculate Heart of Mary (Kongmoon) – Kit Sam Convent |
Residential |
Existing |
2 |
√ |
|
UNI Station |
|||||||
J2 - Entrance B1 |
UNI 1 |
|
Residential |
Existing |
10 |
√ |
|
UNI 2 |
|
School |
Existing |
5 |
√ |
|
|
H - Entrance C2 |
UNI 3 |
Sun
Court |
Residential |
Existing |
23 |
√ |
|
UNI 4 |
The
Belcher's (Tower 8) |
Residential |
Existing |
45 |
√ |
|
|
UNI 5 |
|
Residential |
Existing |
3 |
√ |
|
|
UNI 6 |
|
Residential |
Existing |
21 |
√ |
|
|
J3 - Entrance A |
UNI 7 |
The
Bauhinia |
Residential |
Existing |
9 |
√ |
|
UNI 8 |
|
School |
Existing |
4 |
√ |
|
|
I -
Entrance C1, VS-Z & chiller |
UNI 9 |
The
Belcher's (Tower 3) |
Residential |
Existing |
45 |
√ |
√ |
UNI 10 |
|
School |
Existing |
7 |
√ |
|
|
J -Entrance B2, and J1 - Vent Shaft VS-Y |
UNI 11 |
Sik
On Building |
Residential |
Existing |
9 |
√ |
√ |
UNI 12 |
|
Residential |
Existing |
23 |
√ |
|
|
UNI 13 |
Graceful
Court |
Residential |
Existing |
24 |
√ |
|
|
UNI |
|
Residential |
Existing |
22 |
|
√ |
|
UNI 14 |
Wing
Fu Lau |
Residential |
Existing |
5 |
√ |
√ |
|
G - UNI Construct-ion Shaft |
UNI 15 |
|
Residential |
Existing |
30 |
√ |
|
UNI 16 |
|
Residential |
Existing |
24 |
√ |
|
|
I -
Entrance C1, VS-Z & chiller |
UNI 17 |
|
Residential |
Existing |
6 |
|
√ |
UNI |
|
Residential |
Existing |
6 |
|
√ |
|
E & F - PCWA Barging
Point |
UNI 18 |
|
Residential |
Existing |
24 |
√ |
|
UNI 19 |
Jade
Court (Block A) |
Residential |
Existing |
25 |
√ |
|
|
SYP
Station |
|||||||
N1 - Entrance A1 &
A2 |
SYP 1 |
No.
18-20 Eastern Street |
Residential |
Existing |
5 |
√ |
|
SYP 2 |
No.
28 Sai Woo Lane |
Residential |
Existing |
5 |
√ |
|
|
SYP 3 |
No.
15 Tsz Mi Alley |
Residential |
Existing |
5 |
√ |
√ |
|
SYP 4 |
Ngan Yu Building |
Residential |
Existing |
6 |
√ |
√ |
|
SYP 5 |
|
Residential |
Existing |
21 |
√ |
√ |
|
SYP 16 |
|
Residential |
Existing |
9 |
√ |
√ |
|
M3 -Entrance C |
SYP 6 |
Bon-Point |
Residential |
Existing |
32 |
√ |
√ |
SYP 7 |
|
School |
Existing |
2 |
√ |
√ |
|
M1 -Entrance B1 & B2 |
SYP 8 |
|
Residential |
Existing |
29 |
√ |
|
SYP 9 |
Yee
Shun Mansion |
Residential |
Existing |
19 |
√ |
|
|
SYP 10 |
|
Residential |
Existing |
25 |
√ |
|
|
L1 - Entrance B3 |
SYP 11 |
|
Residential |
Existing |
8 |
√ |
|
SYP 12 |
|
Residential |
Existing |
4 |
√ |
|
|
SYP 13 |
|
Residential |
Existing |
5 |
√ |
|
|
M - KGV Construct-ion Shaft |
SYP 14 |
|
Residential |
Existing |
29 |
√ |
|
SYP 15 |
H.K.S.P.C
Thomas Tam Day Nursery (A/C) |
Nursery |
Existing |
1 |
√ |
|
|
O1 – Ground Treatment |
GT 1 |
Overseas
|
Residential |
Existing |
8 |
√ |
|
GT 2 |
|
Residential |
Existing |
40 |
√ |
|
|
O2 – Ground Treatment |
GT 3 |
|
Residential |
Existing |
22 |
√ |
|
GT 4 |
Yu
Hing Mansion |
Residential |
Existing |
15 |
√ |
|
|
O3 – Ground Treatment |
GT 5 |
Ka
On Building |
Residential |
Existing |
18 |
√ |
|
GT 6 |
|
Residential |
Existing |
35 |
√ |
|
3.22
It should be noted that some
works areas would be designated for material storage and site facilities only,
and the use of PME was not anticipated at these works areas. Therefore, no construction
noise assessment would be needed for these works areas. These works areas
include works area K at Mui Fong Street, works area L at Mui Fong Street
Children’s Playground, and works area M2 at David Lane (Figures 2.19-2.25
refer).
3.23
The proposed WIL is an extension of the Island line from
3.24
Site visits conducted
from November 2005 to August 2006 revealed that NSRs identified within the
Study Area were exposed to noise from the traffic along existing road networks
including
Table 3.4 Key Noise Sources to the Existing NSRs
Location |
Existing Noise Sources affecting NSR |
NSRs near KET |
Traffic noise from |
NSRs near UNI |
Traffic noise from |
NSRs near SYP |
Traffic noise from Queen’s Road West and |
3.25
In accordance with the EIAO-TM, the methodology outlined in
the GW-TM was used for the construction noise assessment. The general approach
is summarized below:
§
Locate the NSRs which would most likely be affected by noise
from the construction work
§
Determine the items of Powered Mechanical Equipment (PME) for
each discrete construction activity, based on available information or agreed
plant inventories
§
Assign sound power levels (SWLs) to the proposed PME
according to the GW-TM or other sources
§
Calculate distance attenuation and screening effects to NSRs
from notional noise source
§
Predict construction noise levels at NSRs in the absence of
any mitigation measures
§
Include a 3 dB(A) façade correction to the predicted noise
levels in order to account for the façade effect at each NSR.
3.26
Sound power levels (SWLs) of the equipment were taken from
Table 3 of GW-TM. Where no sound power
level (SWL) was given in the GW-TM, reference was made to British Standard
5228:Part 1:1997 Noise Control on Construction and Open Sites and
previous similar studies or from measurements taken at other sites in
3.27
According to the design information, the
major fixed plant noise sources identified include ventilation shafts, chillers
and cooling towers. Other building services equipment such as transformer, pump
and emergency generator will be placed inside plant rooms which are expected to
be fully enclosed. A summary of the identified fixed plant noise sources to be
operated are summarised in Table 3.5.
Table
3.5 Summary of Fixed Plant Noise
Sources for the proposed WIL
Location |
Fixed Noise Sources |
ID |
Number of Fixed Plant |
KET Station |
Ventilation
Shaft |
VS-Y,
VS-Z |
2
units |
Chiller
Plant |
CP
1-3 |
3 units |
|
KET
Station – Ex-police Quarters |
Ventilation
Shaft |
KET-VS |
1
unit |
UNI Station -
Entrance C1 |
Ventilation Shaft |
VS-Z1, VS-Z2,
VS-Z3 |
3 units |
Chiller Plant |
CP
1-3 |
3 units |
|
UNI Station – Vent Shaft Y |
Ventilation Shaft |
VS-Y |
1 unit |
SYP Station-Entrance A1 & A2 |
Ventilation Shaft |
VS-Y |
1 unit |
SYP
Station- Entrance C |
Ventilation Shaft |
VS-Z |
1 unit |
Chiller
Plant |
CP
1-3 |
3
units |
3.28
It was assumed in the assessment that chiller
plants would be installed to provide cooling for the three stations. It was assumed that,
for each station there would be 3 chiller units evenly distributed in the
areas designated for their provision.
Indicative
locations of the chiller units are depicted in Figures 3.9, 3.10 and 3.13.
3.29
In the absence of any detailed information and noise
specification of the proposed fixed plant, the maximum
permissible noise emission levels were determined for future detailed design of the
fixed plant.
3.30
For the assessment of noise from the fixed plant, the maximum
permissible sound power levels (Max
SWLs) of the
identified fixed noise sources were determined by adopting standard acoustics
principles. The following formula
was used for
calculating the Max SWLs of the fixed plant.
SPL
= Max SWL
– DC +
FC - BC
where
Sound Pressure Level, SPL
in dB(A)
Maximum
Permissible Sound
Power Level, Max SWL in dB(A)
Distance Attenuation, DC
in dB(A) = 20 log D + 8 [where D is the distance in metres]
Façade Correction, FC in
dB(A) = 3 dB(A)
Barrier Correction, BC in
dB(A)
3.31
It is assumed that
all the fixed plant
within the same location would be operated at the same
time as worst case scenario. Screening correction offered by buildings or other
structures such as office and residential building were taken into account in
calculating the predicted noise levels. According to the GW-TM, effective barriers can result in noise
reduction of 5-10dB(A) for the fixed plant depending on the line of sight of
the representative NSRs. A
positive 3 dB(A) was added to predicted noise levels at the NSRs due to the
façade effect.
3.32
No corrections have been applied for tonality, intermittency
or impulsiveness. If the noise exhibits any of these characteristics during the
operation of the plant, the noise limit should be reduced in accordance with
the recommendation given in Section 3.3 of IND-TM.
3.33
The potential source of noise impact during the construction
phase of the Project would mainly be the use of PME for various construction
activities. As broadly indicated in the
construction program (Appendix 2.2 refers),
the construction of the Project would be from early 2009 to end 2013 / early
2014.
3.34
The length of the proposed WIL is approximately
3.35
Since the Western District is a
highly developed area, demolition of some existing buildings would be necessary
to create space for WIL facilities.
Demolition of buildings could
however have a potential to generate high construction noise levels. The buildings to
be demolished and the proposed usage of WIL at
the cleared site are summarised in the table below.
Table 3.6 Existing Buildings to be Demolished
Existing Buildings to
be Demolished |
Proposed Use |
Blocks A and C, Ex-police Quarter at |
Construction shaft and vent shaft (KET-VS) |
|
KET Station and associated Entrances A and B |
Whitty Street Public Toilet |
UNI Entrance B1 |
Centre Street Market & Centre Street Cooked Food
Centre |
SYP Entrances B1 and B2 |
|
SYP Entrance C |
Tai Shing House, and Nos. 2 & 4 Tsz Mei Alley |
SYP Entrance A1 |
3.36
There
would be four tunnel construction shafts through which excavated spoil from tunneling
would be mucked out. These shafts could
have higher potential of airborne construction noise. The four tunnel construction shafts would be:
·
Works Area A
(Ex-police Quarter) – working shaft for construction of the overrun tunnels and
installation of rails
·
Works Area G (Kennedy Praya) –
The excavated materials from the construction of tunnels
between the east of KET Station and west of SYP Station, and the UNI and SYP
Stations with their associated adits are disposed via the PCWA barging point. Most of this excavated volume will reach
ground level via the construction shaft at Works Area G in the Kennedy Praya
site, and then be transported by a conveyor system across
·
Works Area J (
·
Works Area N1 (
3.37
There would be another construction shaft proposed at the
existing
3.38
There would be two barging points
for transporting of spoil generated from the construction of WIL to designated
public fill reception facilities at Tuen Mun and / or Tseung Kwan O. These two barging points would be located at
Works Area B at KET Abattoir Site and Works Area E at the
3.39
Summarised in Table 3.7 below are key construction
activities at various works areas which would result in elevated construction
noise levels, as well as the PME which were identified as the dominant source
of noise impact. Locations of various
construction activities and works areas are shown in Figures 2.19 - 2.25.
Table 3.7 Summary
of Key Construction Works along the WIL
Location |
Works Area |
Major Noisy Construction Activities |
PME Identified as the Major
Source of Noise Impact |
KET Station |
|||
Underground Magazine |
MA |
Possession of Site |
Drill Rig (SWL=110 dB(A)) |
Construction of Magazine |
Drill Rig (SWL=110dB(A)) Jumbo Drill Rig (SWL=110dB(A)) |
||
Ex-Police Quarter |
A |
Demolition
( |
Hydraulic Breaker (SWL= 110 dB(A)) |
|
|
Pilling/walling |
Pile rig (SWL = 112 dB(A)) |
Abattoir Site |
B |
Rock Crusher Operation |
Crusher (SWL= 118 dB(A)) |
KET Station |
C |
Piling/walling |
Pilling, earth auger (SWL= 114 dB(A)) |
|
|
Excavate rock and base |
Rock Drill (SWL= 123 dB(A)) |
|
|
Commence KET Turnback Tunnel |
Drill Rig (SWL= 110 dB(A)) |
|
D |
Demolish Pools and Grandstand |
Hydraulic Breaker (SWL= 110 dB(A)) |
|
|
Piling/walling |
Pilling, earth auger (SWL= 114 dB(A)) |
|
|
Excavate rock and base |
Rock Drill (SWL= 123 dB(A)) |
|
|
Commence KET to SYP Tunnel |
Drill Rig (SWL= 110 dB(A)) |
UNI Station |
|||
UNI Entrance B1 |
J2 |
Demolition of Whitty Public Toilet
Block |
Concrete Corer (SWL= 117 dB(A)) |
|
|
Piling/ Walling |
Pile Rig (SWL= 112 dB(A)) |
|
|
Excavation – Soft |
Drill Rig (SWL= 110 dB(A)) |
|
|
Excavation – Weak Rock |
Drill Rig (SWL= 110 dB(A)) |
|
|
Excavation - Rock |
Rock Drill (SWL =123 dB(A)) |
UNI Entrance B2 |
J |
Piling / Walling |
Pile Rig (SWL= 112 dB(A)) |
|
|
Excavation - Rock |
Rock Drill (SWL= 123 dB(A)) |
|
|
Excavate adit and running tunnel |
Rock Drill (SWL= 123 dB(A)) |
UNI Entrance C2 |
H |
Piling / Walling |
Pile Rig (SWL= 112 dB(A)) |
|
|
Excavate Rock |
Rock Drill (SWL= 123 dB(A)) |
UNI Entrance C1 |
I |
Piling / Walling |
Pile Rig (SWL= 112 dB(A)) |
|
|
Reinstatement |
Pile Extractor (SWL= 125 dB(A)) |
UNI Entrance A |
J3 |
Piling / Walling |
Pile Rig (SWL= 112 dB(A)) |
|
|
Horizontal Adit |
Crawler mounted rock drill trucks (SWL= 123 dB(A)) |
UNI Vent Shaft VS Y
|
J1 |
Piling / Walling |
Pile Rig (SWL= 112 dB(A)) |
Excavation – Weak Rock |
Rock Drill (SWL= 123 dB(A)) |
||
|
Horizontal Adit |
Crawler mounted rock drill trucks (SWL= 123dB(A)) |
|
UNI Construction Shaft (at |
G |
Piling / Walling |
Pile Rig (SWL= 112 dB(A)) |
|
Excavation - Rock (Horizontal Adit) |
Rock Drill (SWL= 123 dB(A)) |
|
PCWA Barging Point |
E & F |
Possession of Site |
Concrete Saw (SWL = 115 dB(A)) |
|
|
Construction |
Concrete Poker (SWL = 113 dB(A)) |
Rock Crusher Operation |
Crusher (SWL = 118 dB(A)) |
||
SYP Station |
|||
SYP Entrance A1 & A2 |
N1 |
Demolition of Existing Building (No.2-4 Tse Mi Alley & Tai Shing House) |
Hydraulic Breaker (SWL= 110 dB(A)) |
|
|
Install sheet piles and bored piles at playground |
Pile Rig (SWL= 112 dB(A)) |
|
|
Install bored piles and H-piles for shaft |
Pile Rig (SWL= 112 dB(A)) |
|
|
Excavate to tunnel level |
Rock Drill (SWL= 123 dB(A)) |
SYP Entrance B1 & B2 |
M1 |
Demolition of Existing Building ( |
Concrete Corer (SWL= 117 dB(A)) |
|
|
Piling/Walling |
Piling, auger (SWL= 114 dB(A)) |
|
|
Excavate Rock |
Rock Drill (SWL= 123 dB(A)) |
SYP Entrance B3 |
L1 |
Piling/Walling |
Piling, auger (SWL= 114 dB(A)) |
|
|
Installation of Pipe Pile for Soft Ground Tunnel |
Piling, auger (SWL= 114 dB(A)) |
SYP Entrance C |
M3 |
Demolition of Existing Building (David Trench Rehabilitation Centre) |
Hydraulic Breaker (SWL= 110 dB(A)) |
|
|
Piling/Walling |
Piling, auger (SWL= 114 dB(A)) |
|
|
Excavate Rock |
Rock Drill (SWL= 123 dB(A)) |
|
|
Excavate Rock Adit (Hard Rock Excavation) |
Crawler mounted rock drill trucks (SWL = 123dB(A)) |
KGV Construction Shaft |
M |
Piling/Walling |
Piling, auger (SWL= 114 dB(A)) |
Excavate Rock |
Rock Drill (SWL= 123 dB(A)) |
||
Ground Treatment Works |
- |
Ground Treatment |
Drill Rig (SWL= 110 dB(A)) |
3.40
The use of PME for the above construction activities would
be the main source of construction
noise impact. As NSRs in
the vicinity to the works areas were identified,
noise control measures would likely be necessary to ensure that construction
noise impact at the identified NSRs would be within acceptable levels.
3.41
Based on the current design, two ventilation fans would be
installed inside the magazine adit and operated for 24 hours to provide
ventilation to the magazine. Therefore, assessment of construction noise during
restricted hours, which is controlled under section 6 of the NCO, would be
carried out in this EIA report to evaluate the feasibility of construction work
during restricted hours. It should be noted that, however, regardless of the assessment
results, the Noise Control Authority under the NCO will consider an application
based on the relevant technical memoranda issued under the NCO, the
contemporary condition/situations of adjoining land uses and any previous
complaints against construction activities at the site. The assessment carried
out in this EIA report is indicative only and is meant to demonstrate that
practical and feasible approaches could be found.
3.42
The construction of the Project
would induce additional traffic to the existing traffic network. Based on the preliminary construction
programme, it is envisaged that only about 5 construction vehicles per hour (on
average) would be induced by the proposed Project. No insurmountable noise impact due to
project-induced traffic during construction phase would be expected.
3.43
The tunnel section of the proposed alignment will largely
be excavated by drill and blast method.
According to the design
information, there will be not more than 2 blasts per day per work front for
tunnel construction: one blast
in the morning and one in the early evening. Each blast would last for only a few
seconds. Multiple, underground blasts on different work fronts will be carried
out within a single area, spread over five to ten minutes. The blasting as well as the removal of debris
and rocks after blasting would be carried out during non-restricted hours. The broken rock would
be removed by conveyor belt to a barging point at Western
PCWA Site.
3.44
As mentioned in Section
3.13, blasting is under the control of the Dangerous Goods Ordinance. Therefore,
the contractor shall obtain a blasting permit from the Mines Division of CEDD
before carrying out the blasting. The Contractor
shall enclose a method statement including manner of working and protective
measures to protect adjacent land and property when blasting is carried
out.
3.45
Noise from fixed plant associated with an underground
railway would mainly be associated with tunnel
ventilation (e.g. tunnel vent shafts) and
cooling systems for stations (e.g. cooling towers and chillers). Locations of the identified fixed plant
for WIL are shown in Figure 3.8-3.13.
3.46
As broadly illustrated in the construction programme,
various construction activities for WIL may be carried out concurrently during
a particular period. The unmitigated
cumulative noise levels at representative NSRs were predicted. Table
3.8 presents the unmitigated construction noise levels predicted
at representative NSRs.
Table 3.8 Unmitigated
Construction Noise Levels during Non-restricted Hours
NSR ID |
Description |
Predicted
Unmitigated Construction Noise Levels, dB(A) |
EIAO-TM
Noise Criteria, dB(A) |
||
KET
1 |
Kwun
Lung Lau (Block 2) |
72 |
- |
91 |
75 |
KET
2 |
Luen
Fat Apartments |
73 |
- |
90 |
75 |
KET
3 |
Luen
Tak Apartments |
71 |
- |
91 |
75 |
KET
4 |
|
67 |
- |
90 |
75 |
KET
5 |
|
62 |
- |
89 |
75 |
KET
6 |
|
60 |
- |
85 |
75 |
KET
7 |
|
61 |
- |
88 |
75 |
KET
9 |
Hong
Kong Institute of Vocation Education (Tsing Yi) |
43 |
- |
89 |
65/70(1) |
KET
10 |
|
61 |
- |
80 |
65/70(1) |
KET
11 |
Cayman
Rise (Block 1) |
63 |
- |
79 |
75 |
KET
12 |
|
41 |
- |
75 |
75 |
KET
13 |
The
Merton (Block 2) |
40 |
- |
77 |
75 |
KET
14 |
|
63 |
- |
83 |
75 |
KET 15 |
Sisters of the Immaculate Heart of Mary (Kongmoon) – Kit Sam Convent |
77 |
- |
84 |
75 |
KET P1 |
Kwun
Lung Lau |
69 |
- |
87 |
75 |
UNI
1 |
|
42 |
- |
83 |
75 |
UNI
2 |
|
42 |
- |
82 |
65/70(1) |
UNI
3 |
Sun Court |
43 |
- |
91 |
75 |
UNI
4 |
The Belcher's (Tower 8) |
44 |
- |
87 |
75 |
UNI
5 |
PLK Chan Au Big Yan Home for the
Elderly |
44 |
- |
94 |
75 |
UNI
6 |
|
43 |
- |
89 |
75 |
UNI
7 |
The Bauhinia |
46 |
- |
90 |
75 |
UNI
8 |
|
46 |
- |
84 |
65/70(1) |
UNI
9 |
The Belcher's (Tower 3) |
49 |
- |
84 |
75 |
UNI
10 |
|
46 |
- |
85 |
65/70(1) |
UNI
11 |
Sik On Building |
47 |
- |
95 |
75 |
UNI
12 |
|
45 |
- |
91 |
75 |
UNI
13 |
Graceful Court |
46 |
- |
90 |
75 |
UNI
14 |
Wing Fu Lau |
48 |
- |
85 |
75 |
UNI
15 |
|
42 |
- |
87 |
75 |
UNI
16 |
|
42 |
- |
88 |
75 |
UNI
18 |
|
43 |
|
83 |
75 |
UNI
19 |
Jade Court (Block A) |
41 |
|
76 |
75 |
SYP
1 |
No. 18-20 Eastern St |
62 |
- |
96 |
75 |
SYP
2 |
No. 28 Sai Woo Lane |
61 |
- |
94 |
75 |
SYP
3 |
No. 15 Tsz Mi Alley |
66 |
- |
93 |
75 |
SYP
4 |
Ngan Yu
Building |
78 |
- |
95 |
75 |
SYP
5 |
|
62 |
- |
94 |
75 |
SYP
6 |
Bon-Point |
81 |
- |
95 |
75 |
SYP
7 |
|
42 |
- |
92 |
65/70(1) |
SYP
8 |
|
42 |
- |
91 |
75 |
SYP
9 |
Yee Shun Mansion |
43 |
- |
97 |
75 |
SYP
10 |
|
43 |
- |
90 |
75 |
SYP
11 |
|
43 |
- |
93 |
75 |
SYP
12 |
|
43 |
- |
94 |
75 |
SYP
13 |
|
43 |
- |
97 |
75 |
SYP
14 |
|
43 |
|
98 |
75 |
SYP
15 |
H.K.S.P.C Thomas Tam Day Nursery
(A/C) |
45 |
|
87 |
65/70(1) |
SYP
16 |
|
45 |
- |
85 |
75 |
GT
1 |
Overseas |
41 |
- |
87 |
75 |
GT
2 |
|
43 |
- |
87 |
75 |
GT
3 |
|
40 |
- |
82 |
75 |
GT
4 |
Yu Hing Mansion |
40 |
- |
81 |
75 |
GT
5 |
Ka On Building |
44 |
- |
91 |
75 |
GT
6 |
|
44 |
- |
91 |
75 |
Note: (1) EIAO-TM noise limits of Leq(30
min) 70dB(A) for schools during normal hours (65dB(A) during examination
periods)
3.47
The construction noise impact assessment during
non-restricted hours showed that predicted cumulative noise levels at the
representative NSRs would range from 40 to 98 dB(A) which
would exceed the EIAO-TM noise criteria by up to 23dB(A).
3.48
As mentioned in Section 3.41, two ventilation fans would
operate for 24 hours during operation of the magazine. Preliminary construction
noise impact assessment during restricted hours as defined under NCO has been
carried out, and the results showed that predicted noise levels at KET 15
during restricted hours would be 59 dB(A), exceeding the NCO criteria by 14dB(A).
3.49
Mitigation measures are considered necessary in order to
abate the construction noise impacts at all works areas. Appendix
3.2 shows the detailed construction noise calculations for the unmitigated
scenario.
3.50
Max SWLs would be determined by following
the methodology as described in Section
3.30-3.33. Potentially worst affected NSRs were selected for the
assessment and their corresponding Max SWLs were determined in accordance with IND-TM and the EIAO-TM. Appendix
3.3 presents the details of noise assessment for the proposed fixed plant
using both daytime and night time noise criteria. Table 3.9 presents a summary of the
required Max SWLs for key fixed plant along the WIL alignment.
Table 3.9 Maximum Sound Power Level (SWL) for Key Fixed Plant
Source
ID |
Description |
|
Direction
Facing |
Maximum
SWL at daytime, dB(A) |
Maximum
SWL at nighttime, dB(A) |
KET
Station |
|
|
|
|
|
VS-Y |
Ventilation
Shaft |
TVS |
North |
90 |
80 |
|
|
|
West |
90 |
80 |
|
|
TVS |
East |
90 |
80 |
|
|
BEVS |
South |
90 |
80 |
|
|
SEVS |
North |
90 |
80 |
|
|
SSVS |
South |
90 |
80 |
|
|
TSVS |
East |
86 |
76 |
|
|
TEVS |
South |
85 |
75 |
VS-Z |
Ventilation
Shaft |
BEVS |
North |
95 |
85 |
|
|
|
East |
85 |
75 |
|
|
|
South |
85 |
75 |
|
|
TEVS |
North |
94 |
84 |
|
|
TSVS |
South |
85 |
75 |
|
|
SSVS |
South |
85 |
75 |
|
|
TVS |
North |
92 |
82 |
|
|
TVS |
South |
85 |
75 |
|
|
|
West |
92 |
82 |
CP |
Chiller Plant |
1 |
- |
91 |
81 |
|
|
2 |
- |
91 |
81 |
|
|
3 |
- |
91 |
81 |
KET
Ex-police Quarter |
|
|
|
|
|
KET VS |
Ventilation
Shaft |
- |
Northwest
|
106 |
- |
|
|
- |
Southeast
|
105 |
- |
UNI
Station (Entrance C1) |
|
|
|
|
|
VS-Z1 |
Ventilation
Shaft |
BEVS |
North |
91 |
81 |
|
|
|
East |
92 |
82 |
|
|
|
South |
96 |
86 |
|
|
TVS |
West |
92 |
82 |
VS-Z2 |
Ventilation
Shaft |
TVS |
North |
94 |
84 |
|
|
|
East |
94 |
84 |
|
|
|
South |
98 |
88 |
VS-Z3
& CP |
Ventilation
Shaft and Chiller Plant |
1 |
- |
94 |
84 |
|
|
2 |
- |
94 |
84 |
|
|
3 |
- |
94 |
84 |
UNI
Station (Under |
|||||
VS-Y |
Ventilation
Shaft |
SSVS |
North |
83 |
73 |
|
|
|
South |
80 |
70 |
|
|
|
West |
80 |
70 |
|
|
TVS |
North |
82 |
72 |
|
|
TEVS |
South |
83 |
73 |
SYP
Station (Entrance A1 & A2) |
|||||
VS-Y |
Ventilation
Shaft |
TVS |
South |
87 |
77 |
|
|
|
West |
87 |
77 |
SYP
Station (Entrance C) |
|||||
VS-Z |
Ventilation
Shaft |
SSVS |
North |
75 |
65 |
|
|
|
South |
75 |
65 |
|
|
|
West |
76 |
66 |
|
|
SEVS |
North |
80 |
70 |
|
|
BEVS |
North |
81 |
71 |
|
|
|
East |
84 |
74 |
|
|
TVS |
East |
84 |
74 |
|
|
|
South |
83 |
73 |
|
|
TEVS |
South |
82 |
72 |
|
|
|
West |
78 |
68 |
CP |
Chiller Plant |
1 |
- |
80 |
70 |
|
|
2 |
- |
80 |
70 |
|
|
3 |
- |
80 |
70 |
3.51
It should be noted that the calculation of the maximum SWLs
is based on the worst-case scenario including the emergency testing mode. Provided the fixed plants are designed
to meet the Max SWLs as indicated in Table
3.9, no adverse noise impacts
on the NSRs would be expected.
3.52
Due to the extensively developed
and densely populated nature of the
§
Minimise the number of PME.
§
Works would be implemented in phases, where possible, in order to reduce
the number of PME required to be on-site.
3.53
It is proposed to excavate a tunnel more than
3.54
The construction noise assessment
showed that, in the absence of any mitigation measures, there would be
exceedance of the construction noise criteria at some of the NSRs. Various mitigation options have thus been
considered in accordance with the guidelines laid down in the Environmental Impact Assessment Ordinance,
Guidance Note No. 9/2004 “Preparation of Construction Noise Impact Assessment
under the Environmental Impact Assessment Ordinance” (GN 9/2004). It should be noted that
the assumptions used in formulating mitigation measures and their practicality were
based on the best available information from the preliminary design stage of
the Project. Alternative mitigation proposals which could achieve the same
noise reduction effect may be formulated in detailed design stage. Mitigation measures considered
are discussed below.
3.55
Although the noise mitigation effects are easily
quantifiable and the benefits may vary with site conditions and operating
conditions, good site practices are easy to implement and do not impact upon
the works schedule. The site practices
listed below should be followed during each phase of construction:
§
Only well-maintained plant should be operated on-site and
plant should be serviced regularly during the construction program
§
Silencers or mufflers on construction equipment should be
utilized and should be properly maintained during the construction program
§
Mobile plant, if any, should be sited as far from NSRs as
possible
§
Machines and plant (such as trucks) that may be in
intermittent use should be shut down between work periods or should be
throttled down to a minimum
§
Plant known to emit noise strongly in one direction should,
wherever possible, be orientated so that the noise is directed away from the
nearby NSRs
§
Material stockpiles and other structures should be
effectively utilized, wherever practicable, in screening noise from on-site
construction activities.
3.56
In order to reduce the excessive noise impacts at the
affected NSRs during normal daytime working hours, quieter PME are
recommended. The Contractors do not have
to use specific items of quiet plant adopted in this assessment. The Contractors may use other type of quiet
plant, which have the same total SWL, to meet their needs. The quiet PME adopted in the assessment were
taken from the BS5228: Part 1:1997 (Appendix 3.4).
It should be noted that the silenced PME selected for assessment can be found
in
3.57
A list of quieter PME recommended for adoption during the
construction phase is presented in Table
3.10.
Table 3.10 Quieter PME Recommended for Adoption during Construction
Phase
PME |
Power rating/size, weight |
Reference |
SWL |
Dump Truck |
450kW, 50t |
BS C9/39 |
103 |
Tracked Crane |
62kW |
BS C7/114 |
101 |
Tracked Excavator/Loader |
52kW |
BS C3/97 |
105 |
Wheeled excavator/loader fitted with hydraulic rock breaker |
52kW |
BS C8/12 |
106 |
Truck Mixer |
22kW, |
BS C6/23 |
100 |
Poker Vibrators |
0.75 each poker |
BS C6/40 |
98 |
Electrical Vibratory Extractor |
24 Hz |
BS C4/22 |
125 |
Road Roller |
51kW |
BS C8/30 |
101 |
Asphalt Spreader |
90kW, 13t |
BS C8/24 |
101 |
Tracked Excavator Fitted with Hydraulic Breaker |
|
BS C8/13 |
110 |
Consolidated rig (down-the-hole hammer) |
160kW |
BS C11/2 |
112 |
Tracked Crane |
58kW, 34t |
BS C7/112 |
102 |
Sheet Steel Piling, Hydraulic |
220 |
BS C4/13 |
106 |
3.58
The use of movable
barrier for certain PME could further alleviate the construction noise impacts. In general, 5dB(A) reduction for movable PME
and 10dB(A) for stationary PME can be achieved depending on the actual design
of movable noise barrier.
3.59
Table
3.11
shows the assumed noise reduction effects achieved by the movable noise barrier
for certain items of PME. The Contractor
shall be responsible for
design of the movable noise barrier with due consideration given to the size of
the PME and the requirement of intercepting the line of sight between the NSRs
and PME. Barrier material of surface mass
in excess of
3.60
Noise enclosure would
be used to cover stationary PME such as air
compressor and concrete pump. With the adoption of the
noise enclosure, the PME could be completely
screened, and noise
reduction of 15 dB(A) could be achieved with reference to Paragraph 4.5 of EIAO Guidance Note
No. 9/2004.
3.61
Enclosing a rock drill in a portable or fixed acoustic enclosure with suitable
ventilation would result in up to 20dB(A) noise reduction (Table B1 of BS5228
refers). The acoustic enclosure should
enclose the PME as fully as possible. It
should possess adequate insulation so that noise energy would not readily pass
through them. A sheet material mass of
3.62
The noise insulating cover (NIC) would be used to cover some of the
mucking out points where necessary and practical. It was reported in the EIA Report for the Kowloon
Southern Link project that the NIC could achieve an overall noise reduction of
22dB(A). Typical configuration of
acoustic panels that could achieve this insulation requirement would be 1.5 GS
outer skin,
3.63
To reduce noise emission from the
ventilation fans, silencers are also recommended to be used in fan ventilation system
to attenuate noise generated during fan operation to achieve a noise reduction
of 15dB(A).
The Contractor shall
be responsible for selection of appropriate silencers for the ventilation fans.
3.64
Noise insulating
fabric (the Fabric) would be adopted for certain PME (e.g. drill rig, piling
auger etc). The Fabric should be lapped
such that there would be no opening or gaps on the joints. With reference to
MTRC Contract C4420 Tsim Sha Tsui Modification Noise Assessment Report for
Variation of Environmental Permit (July 2003) and the technical data from manufacturer, a noise reduction of
over 10 dB(A) could be achieved with the use of the
Fabric. As a conservative approach, a noise reduction of 10
dB(A) for the PME lapped with the Fabric
was assumed in this assessment.
3.65
The Fabric would also be used for screening the noise emitted from the
use of PME for the demolition works at the
3.66
A summary of the assumed noise
reduction effects achieved by the use of movable noise barrier,
noise enclosure, silencer, acoustic enclosure,
the Fabric as well as the Noise Control Curtain for certain item of PME
is presented in Table 3.11.
Table 3.11 Noise Mitigation Measures for Certain PME during
Construction Phase
PME |
Mitigation Measures Proposed |
Noise Reduction, dB(A) |
Air Compressor |
Enclosure/Shed |
15 |
Breaker |
Movable Noise Barrier |
10 |
Mini backhoe |
Movable Noise Barrier |
5 |
Pile Rig |
The
Fabric |
10 |
Generator, super silenced |
Movable Noise Barrier |
10 |
Backhoe |
Movable Noise Barrier |
5 |
Ventilation fan |
Silencer |
15 |
Crane |
Movable Noise Barrier |
5 |
Rock Drill |
Acoustic
Enclosure |
20 |
Concrete pump |
Enclosure/Shed |
15 |
Poker, vibratory, hand-held |
Movable Noise Barrier |
10 |
Pile Extractor |
The
Fabric |
10 |
Power Rammer |
The
Fabric |
10 |
Pilling, earth auger |
The
Fabric |
10 |
Hydraulic Breaker |
Movable Noise Barrier |
5 |
Compressor |
Enclosure/Shed |
15 |
Wheel Loader |
Movable Noise Barrier |
5 |
Crusher |
Movable Noise Barrier |
5 |
Concrete Pump |
Enclosure/Shed |
15 |
Shotcrete Pump |
Enclosure/Shed |
15 |
Grout Pump |
Enclosure/Shed |
15 |
Concrete Corer |
Enclosure/Shed |
15 |
Grout Plant |
Movable Barrier |
10 |
Grout Mixer |
Movable Barrier |
5 |
Excavator |
Movable Barrier |
5 |
Lorry Crane |
Movable Barrier |
5 |
Crawler Crane |
Movable Barrier |
5 |
Piling Hydraulic |
The Fabric |
10 |
Sheet Piling Machine |
The Fabric |
10 |
Rock Drill |
Acoustic Enclosure |
20 |
Air compressor, Hand-held breaker & Hydraulic breaker
(used for the demolition works at the Ex-police Quarter site) |
Noise Control Curtain |
5 |
3.67
The use of temporary noise barriers would be an effective
mean to alleviate the noise impact arising from the construction works,
particularly at NSRs
at lower levels.
Site surveys revealed that NSRs located
within the Assessment Area would
mainly be mid/high-rise in nature (about
10-40 storeys). Having considered the engineering constraints, nature of
construction work, height and location of NSRs, the practical heights of the temporary
noise barrier have been determined to screen their sensitive façade from
viewing the ground-level construction equipment within the site.
3.68
The practicality of using
temporary noise barriers would also
depend on whether there would be sufficient space
available. Hence
the use of temporary noise barrier would not be practicable
for all areas. In
particular, temporary noise barriers would not be suitable for erecting along a
lane closure in highway as the barrier might be knocked down by vehicles.
3.69
Having taken into account all the
factors mentioned above, temporary barriers would be proposed at the works area
C, i.e. the
3.70
At SYP Entrance A1 and A2 (
3.71 A deck over would be provided to cover the excavation area at the Works Area J – UNI Entrance B2, J3 – UNI Entrance A, G – UNI Construction Shaft and L1 - SYP Entrance B3. The typical configuration of the deck is shown in Figures 3.24. The deck would fully covered the opening of the excavation area / shaft such that noise would not be leaked out from the shaft or tunnel. The inside of the deck cover should be lined with sound-absorbent materials so that a noise reduction of 20dB(A) can be achieved.
3.72
It is proposed that works area J2 for
the construction of UNI Entrance B1 would be fully
enclosed after piling
works are completed to reduce the noise emission due to
the excavation activities and construction of entrance. With reference to paragraph
4.5 of EIAO Guidance Note No. 9/2004, the use of noise enclosure could achieve
a noise reduction of 15dB(A). The
typical configuration of the full enclosure is shown in Figures 3.24.
3.73
High level of noise exceedance would
be encountered for sites which involve demolition of buildings.
In view of this, concrete crusher
(SWL=103dB(A)), which is a quieter
alternative to conventional hydraulic breaker (SWL=110dB(A)),
has been proposed for use at works areas where practicable.
3.74
Concrete crushers would be used for demolishing the Whitty Street Public Toilet
in works area J2 (UNI Entrance B1),
David Trench Rehabilitation Centre in works area M3
(SYP Entrance C),
and Centre Street Cooked Food Market at works area M1 (SYP
Entrances B1 and
B2). The
practicality of using concrete crushers at these locations has been confirmed
by the Project Proponent.
3.75
With the
implementation of all above-mentioned mitigation measures, the total SWLs of each
activity were predicted, and are presented in Appendix 3.4.
The predicted noise levels at most of the NSRs would comply with the EIAO-TM noise
criteria. Table 3.12 presents the
mitigated noise levels during normal daytime working hours at NSRs. A sample
calculation of construction noise levels for mitigated scenario is presented in
Appendix 3.4.
Table 3.12 Summary of
Mitigated Construction Noise Levels during Non-restricted Hours
NSR ID |
Description |
Predicted
Mitigated Construction Noise Levels, dB(A) |
EIAO-TM
Noise Criteria, dB(A) |
||
KET
1 |
Kwun
Lung Lau (Block 2) |
64 |
- |
74 |
75 |
KET
2 |
Luen
Fat Apartments |
62 |
- |
73 |
75 |
KET
3 |
Luen
Tak Apartments |
60 |
- |
76 |
75 |
KET
4 |
|
56 |
- |
76 |
75 |
KET
5 |
|
51 |
- |
77 |
75 |
KET
6 |
|
49 |
- |
71 |
75 |
KET
7 |
|
50 |
- |
76 |
75 |
KET
9 |
Hong
Kong Institute of Vocational Education (Tsing Yi) |
43 |
- |
73 |
65/70(1) |
KET
10 |
|
59 |
- |
70 |
65/70(1) |
KET
11 |
Cayman
Rise (Block 1) |
61 |
- |
69 |
75 |
KET
12 |
|
41 |
- |
65 |
75 |
KET
13 |
The
Merton (Block 2) |
40 |
- |
65 |
75 |
KET 14 |
|
61 |
- |
72 |
75 |
KET 15 |
Sisters of the Immaculate Heart of Mary (Kongmoon) Kit Sam Convent |
64 |
- |
75 |
75 |
KET P1 |
Kwun
Lung Lau |
59 |
- |
70 |
75 |
UNI
1 |
|
42 |
- |
83 |
75 |
UNI
2 |
|
42 |
- |
66 |
65/70(1) |
UNI
3 |
Sun Court |
43 |
- |
72 |
75 |
UNI
4 |
The Belcher's (Tower 8) |
44 |
- |
68 |
75 |
UNI
5 |
PLK Chan Au Big Yan Home for the
Elderly |
44 |
- |
75 |
75 |
UNI
6 |
|
43 |
- |
70 |
75 |
UNI
7 |
The Bauhinia |
46 |
- |
75 |
75 |
UNI
8 |
|
46 |
- |
69 |
65/70(1) |
UNI
9 |
The Belcher's (Tower 3) |
49 |
- |
71 |
75 |
UNI
10 |
|
46 |
- |
71 |
65/70(1) |
UNI
11 |
Sik On Building |
47 |
- |
77 |
75 |
UNI
12 |
|
45 |
- |
77 |
75 |
UNI
13 |
Graceful Court |
46 |
- |
75 |
75 |
UNI
14 |
Wing Fu Lau |
48 |
- |
68 |
75 |
UNI
15 |
|
42 |
- |
72 |
75 |
UNI
16 |
|
42 |
- |
73 |
75 |
UNI
18 |
|
43 |
- |
75 |
75 |
UNI
19 |
Jade Court (Block A) |
41 |
- |
68 |
75 |
SYP
1 |
No. 18-20 Eastern Street |
62 |
- |
79 |
75 |
SYP
2 |
No. 28 Sai Woo Lane |
61 |
- |
77 |
75 |
SYP
3 |
No. 15 Tsz Mi Alley |
66 |
- |
77 |
75 |
SYP
4 |
Ngan Yu
Building |
65 |
- |
81 |
75 |
SYP
5 |
|
62 |
- |
82 |
75 |
SYP
6 |
Bon-Point |
42 |
- |
75 |
75 |
SYP
7 |
|
42 |
- |
74 |
65/70(1) |
SYP
8 |
|
43 |
- |
86 |
75 |
SYP
9 |
Yee Shun Mansion |
43 |
- |
76 |
75 |
SYP
10 |
|
43 |
- |
82 |
75 |
SYP
11 |
|
43 |
- |
82 |
75 |
SYP
12 |
|
43 |
- |
83 |
75 |
SYP
13 |
|
43 |
- |
82 |
75 |
SYP
14 |
|
45 |
- |
72 |
75 |
SYP
15 |
H.K.S.P.C Thomas Tam Day Nursery
(A/C) |
45 |
- |
70 |
65/70(1) |
SYP
16 |
|
68 |
- |
83 |
75 |
GT
1 |
Overseas |
41 |
- |
74 |
75 |
GT
2 |
|
43 |
- |
75 |
75 |
GT
3 |
|
40 |
- |
69 |
75 |
GT
4 |
Yu Hing Mansion |
40 |
- |
69 |
75 |
GT
5 |
Ka On Building |
44 |
- |
77 |
75 |
GT
6 |
|
44 |
- |
77 |
75 |
Note: (1) EIAO-TM noise limits
of Leq(30 min) 70dB(A) for schools during normal hours (65dB(A)
during examination periods)
3.76
With the implementation of mitigation measures, the preliminarily
predicted noise levels at KET 15 during restricted hours due to the 24 hour operation
of ventilation fans at the temporary magazine site would be 44 dB(A), which would
comply with the NCO criteria.
3.77
With the
fixed plant properly designed to meet the maximum SWL listed in Table 3.9, there would not be any
residual impact predicted. However,
it is still recommended that the following noise reduction measures should be
considered as far as practicable during detailed design:
§
Choose quieter plant such as those which have been effectively
silenced.
§
Include noise levels specification when ordering new plant (including chillers
and E/M equipment).
§
Locate fixed plant/louver away from any NSRs as far as practicable.
§
Locate fixed plant in walled plant rooms or in specially designed
enclosures.
§
Locate noisy machines in a basement or a completely separated building.
§
Install direct noise
mitigation measures including silencers, acoustic louvers and acoustic
enclosure where necessary.
3.78
Residual construction noise impacts were identified,
as presented in Table 3.13 below.
Table 3.13 Predicted Residual Impacts Due to the
Proposed Project
NSR ID |
Location
|
Affected floor |
|
Duration of Residual Impact (months) |
KET 1 |
Kwun
Lung Lau (Block 2) |
- |
- |
- |
KET 2 |
Luen
Fat Apartments |
- |
- |
- |
KET 3 |
Luen
Tak Apartments |
1-5/F |
1 |
2 |
KET 4 |
|
1-12/F |
1 |
2 |
KET 5 |
|
1-4/F |
1-2 |
3 |
KET 6 |
|
- |
- |
- |
KET 7 |
|
1-5/F |
1 |
3 |
KET 9 |
Hong
Kong Institute of Vocation Education (Tsing Yi) |
1-7/F |
1-3 |
5 |
KET 10 |
|
- |
- |
- |
KET 11 |
Cayman
Rise (Block 1) |
- |
- |
- |
KET 12 |
|
- |
- |
- |
KET 13 |
The
Merton (Block 2) |
- |
- |
- |
KET 14 |
|
- |
- |
- |
KET 15 |
Sisters of the Immaculate Heart of Mary
(Kongmoon) – Kit Sum Convent |
- |
- |
- |
KET P1 |
Kwun Lung Lau |
- |
- |
- |
UNI 1 |
|
1-10/F |
1-8 |
6 |
UNI 2 |
|
- |
- |
- |
UNI 3 |
Sun Court |
- |
– |
– |
UNI 4 |
The Belcher's (Tower 8) |
- |
- |
- |
UNI 5 |
PLK Chan Au Yan Home for the
Elderly |
- |
- |
- |
UNI 6 |
|
- |
- |
- |
UNI 7 |
The Bauhinia |
- |
- |
- |
UNI 8 |
|
- |
- |
- |
UNI 9 |
The Belcher's (Tower 3) |
- |
- |
- |
UNI 10 |
|
1-7/F |
1 |
3 |
UNI 11 |
Sik On Building |
1 – 2/F |
1 – 2 |
4 |
UNI 12 |
|
1/F |
2 |
4 |
UNI 13 |
Graceful Court |
- |
- |
- |
UNI 14 |
Wing Fu Lau |
- |
- |
- |
UNI 15 |
|
- |
- |
- |
UNI 16 |
|
- |
- |
- |
UNI 18 |
|
- |
- |
- |
UNI 19 |
Jade Court (Block A) |
- |
- |
- |
SYP 1 |
No. 18-20 Eastern St |
1-4/F |
1-4 |
23 |
SYP 2 |
No. 28 Sai Woo Lane |
1-3/F |
1-2 |
6 |
SYP 3 |
No. 15 Tsz Mi Alley |
1-5/F |
1-2 |
9 |
SYP 4 |
Ngan Yu
Building |
1-6/F |
1-6 |
26 |
SYP 5 |
|
1-21/F |
7 |
4 |
SYP 6 |
Bon-Point |
- |
- |
- |
SYP 7 |
|
1-2/F |
2-4 |
19 |
SYP 8 |
|
1-5/F |
1-11 |
27 |
SYP 9 |
Yee Shun Mansion |
1/F |
1 |
5 |
SYP 10 |
|
1-5/F |
1-7 |
15 |
SYP 11 |
|
1-4/F |
1-7 |
10 |
SYP 12 |
|
1-4/F |
1-8 |
9 |
SYP 13 |
|
1-3/F |
1-7 |
11 |
SYP 14 |
|
- |
- |
- |
SYP 15 |
H.K.S.P.C Thomas Tam Day Nursery
(A/C) |
- |
- |
- |
SYP 16 |
|
3 – 9/F |
2-8 |
5 |
GT 1 |
Overseas |
- |
- |
- |
GT 2 |
|
- |
- |
- |
GT 3 |
|
- |
- |
- |
GT 4 |
Yu Hing Mansion |
- |
- |
- |
GT 5 |
Ka On Building |
1/F |
1-2 |
2 |
GT 6 |
|
1/F |
1-2 |
2 |
3.79
Residual impacts of 1-11dB(A)
would be expected, mainly due to the limited separation distance between NSRs
and the works areas. The feasibility of
providing noise reduction measures to further reduce the residual impacts has
been examined, and discussed below.
3.80
In view of the high noise exceedance during the construction
phase of the Project, further mitigation measures have been explored. However,
with the consideration of on-site condition and safety of site workers and passers-by,
some mitigation measures are considered not practicable. For example, though
the use of movable noise barriers is effective in reducing noise level, it
would not be feasible to be used for demolition of existing buildings since the
demolition process would start from the top of the buildings and erecting the barriers
on the top floor of the buildings would give rise to safety issues. In
addition, the number of movable noise barriers used on site should be
restricted to minimize the chance of works site accidents and prevent the
barriers from collapse. Further mitigation measures which are considered
practical for implementation are discussed below.
3.81
For some of the works areas
including Works Area C, D, M1, L1, M3 and M, using piling auger for installing
pipe piles would cause residual impacts at some of the NSRs. Alternative piling method by using vibratory
hammer or silent piler such as for installing sheet piles has been
considered. This alternative would
induce local deformation and thus considered to be unsafe and impractical.
3.82
Demolition of some existing buildings
would involve the use of hydraulic breakers.
Hydraulic breakers would have high noise emissions. For safety reasons, noise barriers could not
be used to screen the noise generated by breakers. It has been suggested in the EIAO Guidance
Note. 9/2004 that the use of concrete crushers instead of hydraulic breakers in
the demolition of buildings could be considered for reducing the impacts. The practicality of using this alternative
has been reviewed.
3.83
One major limitation of the
concrete crusher is that its jaws would need to be able to get to both sides of
the concrete element (beam, column, slab etc.) before it can crush or cut that
element. This generally requires a
number of holes to be cut into the structure at each floor level to enable the
crusher to commence its work. The most
effective way of making these holes in the structure is by replacing the jaws
on the backhoe with a more conventional pneumatic breaker. This will obviously create as much noise as
the more familiar method of concrete demolition but for a reduced period of
time. For small structures, these holes
in the structures can be made using concrete corer. However, for structures with considerable
size / thickness of concrete elements that would need to be demolished, conventional
hydraulic breakers should be deployed from a practical engineering
viewpoint. This would be applicable to
the case of Kennedy Town Swimming Pool demolition at Works Area D.
3.84
Demolition using a concrete
crusher would be generally less controlled than demolition using a hydraulic
breaker since it removes elements of the structure in larger pieces which then
have to be lowered carefully to ground level.
This is particularly difficult to control in buildings which have a
small plan area such as those buildings at
3.85
The use of hydraulic breaker for
demolishing David Trench Rehabilitation Centre at Works Area M3 cannot be fully
replaced by the sole use of concrete crusher.
The breaker has to be retained to form holes in the thick concrete
elements of this building before the concrete crusher can work by getting to
both sides of concrete element. However,
concrete crusher would be used at this location wherever applicable, and the
conventional demolition method would only be applied if absolutely necessary at
specific part of the demolition such that the construction noise impact can be minimized.
3.86
It should also be noted that
demolition using a concrete crusher would generally be 50% slower than the more
conventional hydraulic breaker.
3.87
With the consideration of all
mitigation measures and alternative construction methods, residual impacts are
still predicted at some of the works areas. In view of the residual impacts, feasibility
of adopting alternative construction methods/PME is further reviewed. Site-specific
constraints of implementing various direct mitigation measures are also discussed
below.
3.88
With the use of noise control
curtain to screen the noise generated from the use of breakers, the demolition
of the existing
3.89
Apart from using noise control
curtain (Section 3.64 refers), the practicality of using movable barriers for
reducing the residual impact due to demolition works has been reviewed. However, as the PME would be placed on top of
the buildings to be demolished, it would be unsafe to erect movable barriers for
the PME there. Therefore, it would not
be feasible to use movable barriers in this case. It was considered that the use
of noise control curtain would be the only feasible mitigation option for
controlling the noise from demolition works based on available preliminary
design information. It would also be
recommended that noisy demolition works be scheduled as far as practicable to
avoid examination hours in view of the predicted residual impacts at the school
NSR (KET 9).
3.90
Having taken into account the
above, it was considered that all direct mitigation measures have been
exhausted and the construction noise impact at this works area has been
minimized.
3.91
The construction of KET Station
would be undertaken at these two works areas.
Residual impacts were predicted at NSRs KET3-KET5 and KET7. Construction activities that would cause the residual
impacts would include piling as well as demolition of the existing Kennedy Town
Swimming Pool site.
3.92
During piling, the use of piling auger would generate high
noise levels. However, as mentioned in Section
3.79, the use of alternative piling method would not be feasible in this
works area. To abate the noise from the piling auger, noise insulating fabric
has been proposed to cover the plant and a noise reduction of 10dB(A) could be
achieved. The practicality of various mitigation measures for
ameliorating other PME including cranes and trucks has been reviewed. Yet, as
piling would be carried out along the site boundary, mitigation measures such
as movable noise barriers would not be feasible due to spatial limitation.
3.93
Rock drill, which would be the noisiest PME
amongst various equipment to be used, has been proposed for excavation works at these two
works areas. Such would be needed for excavation of rock. To specifically control the emission of noise
from this key source of noise impact, an acoustic enclosure as mentioned in Section 3.60
has been proposed to cover this equipment. It
was envisaged that 20dB(A) noise reduction could be achieved by using
the acoustic enclosure to cover the rock drill.
3.94
Demolition of the existing
Kennedy Town Swimming Pool would result in residual impacts at NSRs
nearby. As mentioned above, movable
barriers would be unsafe and not feasible for screening the noise generated
from the equipment when demolition works are undertaken. The use of concrete crusher instead of
hydraulic breakers has then been considered.
However, as mentioned in Section
3.81, given the considerable size / thickness of concrete elements of the
swimming pool structure, the use of hydraulic breakers would be necessary.
3.95
In addition, temporary noise
barriers would be provided along the southern and northern boundary of the
works area C after piling. The noise levels from various construction
activities such as excavation and construction of station box would be lowered
with the temporary barriers in place. Based on the construction noise
calculation, no noise exceedance would be predicted for those construction
activities with temporary barriers in place. Therefore, the erection of
temporary barriers along site boundary is considered effective in alleviating
the construction noise impact.
3.96
With the use of all practicable
direct mitigation measures and alternative construction methods/PME, it is
considered that the construction noise impact due to the use of PME for various
construction activities at these two works areas has been minimized.
3.97
Key activities to be undertaken
at this works area would include the demolition of the existing Whitty Street
Public Toilet, piling, excavation and construction of entrance. Construction
activities at this works area would result in residual impacts at NSR UNI 1,
which is located immediately next to the works area.
3.98
The residual impact would primarily be due to the demolition
activity. In view of the large residual impact, quieter alternative demolition
including the use of concrete crusher, which has a much lower SWL, has been
adopted instead of the conventional use of hydraulic
breaker. Noise level would be reduced with the use of concrete crusher. Additionally,
enclosure would be applied to concrete corer such that the noise levels could
be further reduced.
3.99
The use of movable noise barriers during demolition has also
been reviewed. However, it was considered not practical during the demolition
of the toilet block due to spatial limitation and safety reasons.
3.100
Another construction activity which would lead to residual impact would be
piling. The large residual impact is due to the fact that NSR UNI 1 would be
located immediately next to the works area boundary
at which
piling works would be carried out. To reduce the construction noise impact, the practicality of
using various direct mitigation measures during piling has been reviewed. Pile rig would be the nosiest
PME to be used, and it is proposed that a noise insulating
fabric would be used to cover it to achieve a noise reduction of 10dB(A). Furthermore, there would be insufficient space
for erecting noise barriers during piling.
Given these engineering constraints, mitigation measures to further
reduce the residual impact from piling works were not available.
3.101
Excavation would also result in high residual
noise impacts at
NSR UNI1. To further minimize the construction noise impact, the entire
works area would be fully enclosed after piling. As mentioned in Section 3.71, the provision of full
noise enclosure at this works area could achieve a noise reduction of 15dB(A). The
SPL generated from the excavation activities and construction of entrance would
be reduced with the full noise enclosure in place.
3.102
It was considered that all direct practicable
noise mitigation measures have been exhausted, and
alternative quieter construction method/PME would be used where practicable to
minimise the residual noise impacts due to works conducted at this works
area.
3.103
Minor residual impact would be expected
at the school NSR UNI10 located
in proximity of this works area. The use of pile extractor and power rammer for
reinstatement
works at this works area would be the main
reason for the predicted residual impact.
Noise insulating fabric has been proposed to control the emission of
noise from the operation of these two PME.
However, other feasible direct mitigation measures to further reduce the
residual noise impact were not available. The residual construction noise impact was
considered to be controlled to a minimum level with the proposed mitigation
measures in place.
3.104
The use of pile rig for piling
works at this works area would result in high construction noise levels at
neighbouring NSRs. Noise insulating
fabric has already been proposed to alleviate the noise impact associated with
the use of this PME. With this mitigation
in place, NSR UNI12 would still be subject to slight residual impact when
piling works would be conducted.
Residual impact could be further reduced by enclosing the pile rig. However,
in view of the nature of the piling works and size of the pile rig, using
enclosure to cover the pile rig was considered not feasible. Alternative piling method by using vibratory
hammer or silent piler has been rejected based on the reasons given in Section 3.79. The predicted residual impacts have been
minimised as no further practical direct mitigation measures were
available.
3.105
Excavation would also generate high construction noise levels at this works area. To abate the noise level during excavation, decking
over has been proposed to cover the noise from the construction shaft. However, decking could not be installed at
early stage of excavation. Sufficient
depth would need to be excavated to allow adequate underground working space
for the excavation to be proceeded before the ground opening could be covered
with the decking. Hence, for
conservative noise assessment, it was assumed that the deck would not be
provided at initial stage of excavation i.e. weak rock excavation. The deck was assumed to be in place when rock
excavation is conducted.
3.106
The feasibility of using NIC to
cover the operation of PME during excavation has been examined. Nevertheless, since the construction shaft
would take up almost the entire works area, there
would be insufficient space to
construct the necessary foundation for the NIC. Hence,
it would not be feasible to adopt this mitigation option.
3.107
Residual construction noise
impacts due to works at this location have been minimised as all practicable mitigation
measures including the use of movable noise barriers, deck
over, enclosure,
silencer and noise insulating fabric have already been
exhausted.
3.108
Minor residual impacts of 1-2
dB(A) were predicted at NSR UNI 11 which is located at about
3.109
As revealed from the construction plant inventories, pile
rig would have the highest noise emission level among all other
PME used for piling. Noise insulating fabric which
could achieve 10dB(A) noise reduction
has been
proposed to cover the pile rig. However, minor residual impact would still be
predicted. To further reduce the
construction noise impact, it would be necessary to identify practical measures
which could reduce the noise emission from the pile rig by more than
10dB(A). One possible option would be
the use of noise enclosure. However, as
discussed in Section 3.102, given
the nature of the piling works and size of the pile rig, noise enclosure would
not be a feasible option. Alternative
piling method by using vibratory hammer or silent piler has been rejected based
on the reasons given in Section 3.79. The predicted residual impacts have been
minimised as further practical direct mitigation measures were not
available.
3.110
Throughout the process of excavating the shaft and
horizontal adit, noise insulating cover could be employed for covering
the opening of the shaft such that the noise from the PME beneath could be reduced.
A noise reduction of up to 20dB(A)
could be achieved after the use of this mitigation. However, minor residual impact would still be
predicted. Practical mitigation measures to further reduce the residual impacts
are not available.
3.111
It was predicted that the
reinstatement works would also result in minor residual impact at
the NSR UNI11. It can be observed that power
rammer, being the nosiest PME, would be covered by a noise insulating fabric.
Mitigation measures for other noisy plants, including truck, vibratory roller,
concrete lorry mixer and asphalt paver have also been explored. However, due to the mobile nature of these equipment, further
practical mitigation measures were not available. In particular, the use of movable noise barrier or
noise enclosure would be considered not practical.
3.112
All direct mitigation measures
have been looked into and applied where practicable to minimise the noise
impacts due to works at this location.
3.113
The use of PME for demolishing
existing buildings and excavation activities would result in residual impacts at NSRs SYP 1-5 and 16. The practicality of various mitigation proposals to
further alleviate the residual noise impact has been examined.
3.114
Due to spatial constraints and
safety concerns, the use of movable noise barriers for shielding the noise from
the use of PME for demolition was not recommended. Alternative quieter demolition method such as
the use of concrete crusher has also been considered. This
option was however discarded based on reasons given in Section 3.82.
Conventional demolition method using
hydraulic breaker was assumed to be used at this works area.
3.115
The practicability of using noise
control curtain was also investigated for the demolition works. This works area
is a highly congested site when compared with the Ex-police quarter site. There
would not be enough space to support the scaffold robust required supporting
the noise control curtain and the substantial supporting structure required
supporting the heavy weight of the fabric. Therefore, the use of noise control
curtain is not recommended at this stage. However, the practicality of using
the noise control curtain in this works area could be subject to further
investigation in the detailed design stage.
3.116
The use of truck for transporting
spoil from excavation works would be the other cause of the residual
impact. However, due to its mobile nature,
it would not be feasible to use mitigation measures such as movable noise barrier and noise
enclosure. In addition to
trucks, noise from hand-held breakers and backhoes would also contribute much
to the high noise level. In view of this, movable noise barrier has been
proposed for these two PME to alleviate the associated nose impact. Rock drill would be used during excavation to tunnel level. Given this PME would have a high noise
emission level, an acoustic enclosure has been proposed to cover this
equipment such that its noise emission level could be cut by about 20dB(A).
3.117
To further control the noise
impact, a NIC would
be used to cover the mucking out point upon
commencement of tunnel construction. The
NIC would help reduce the noise due to mucking out activities. It should be noted that the feasibility of providing
the NIC
at earlier stage of excavation works such as immediately after the
completion of piling
has been examined. However, since
this works
area would be used as the launching shaft for the TBM, the NIC could
only be installed following the launching of the two TBM for tunnel
construction. As a result, it was
assumed in the calculation that the NIC would only be in place upon
commencement of tunnel construction.
3.118
Temporary barriers have been proposed to shield the noise from the water
cooling towers that would be used during tunnel construction. Further reduction in noise impact could be
achieved by using full enclosure.
However, operating cooling towers in an enclosure would have heat
dissipation problems.
3.119
Other noise mitigation measures including
movable barriers, noise insulating fabric, silencer and enclosure have been
proposed to ameliorate the noise impact due to the use of various PME for
different
construction activities at this works area. The noise impacts arising from works at this
location have been minimised through the adoption of all practicable mitigation
measures discussed above.
3.120
It was predicted that the
demolition of existing David Trench Rehabilitation Centre and excavation
activities at this works area would lead to residual noise impact at the school
NSR SYP7 .
3.121
A review of the practicality of
using alternative quieter concrete crusher for demolition works at David Trench
Rehabilitation Centre has been conducted.
As discussed in Section 3.83,
the use of hydraulic concrete crusher will be used locally for specific
demolition works wherever applicable to minimise the construction noise
impact. However, the hydraulic breaker
would be retained to make initial holes through thick concrete slabs and
structural walls especially those with steel reinforcement. However, the use of the breaker would play a
supplementary role and so its utilization rate would only be in the order of
30%. The concrete crusher would be used
as far as practicable to minimise the noise impact from the demolition works.
3.122
The feasibility of adopting other direct mitigation measures
for the demolition works at this works area has been reviewed. The use of
movable noise barrier is considered impractical and unsafe to be placed on top
of the building to be demolished. Though trucks would be placed on ground
level, it would not be viable to use either movable barriers or noise
enclosures to screen the noise since they are mobile in nature. In this
regards, noise
impact caused by demolition works at this works area could not be reduced
further as no other practicable mitigation measures would be
available.
3.123
Throughout the entire excavation process, NIC would be provided to
cover the opening of the shaft. Those
PME used for excavation would be placed underneath
the cover
such that the noise could be effectively screened. A noise reduction of 20dB(A)
could be achieved with the use of NIC. For those PME
including dump
trucks, cranes and concrete lorry mixer which have to
operate outside
the cover, other direct mitigation measures have also been
considered.
However, it would be not be practicable to use movable noise barriers or
noise
enclosures to cover these mobile equipment. Further
practicable measures to mitigate the noise impact were not available.
3.124
The use of trucks during the carrying out of
station
fitout would also cause minor noise exceedance. Similarly, due to
the mobile nature of trucks, no mitigation measures could be provided to
alleviate the noise impact.
3.125
Having taken into consideration the
above factors, the mitigation proposal in this works area is
considered to be exhausted and the construction noise impact has been
minimized.
3.126
Piling, excavation, demolition of
the Centre Street Market West Block and station fitout would result in residual impacts at
NSRs SYP8-10
located in
close proximity to this works area. Mitigation
measures to further ameliorate the predict residual impact have been
considered.
3.127
Piling works would be conducted
at the works area boundary. The
separation distance between NSRs and the location at which piling works would
be carried out would be small, and this would be the main reason for the noise
exceedances. Amongst various equipment
to be used for piling, piling auger would be the noisiest equipment. A noise insulating fabric which would result
in a noise reduction of 10dB(A) has been deployed to cover the noise from this
noisiest equipment. However, residual impact would still be
predicted. Either the use of mitigation
measure such as noise enclosure which could cut the noise from the use of
piling auger by more than 10dB(A) or alternative piling method using quieter
PME such as vibratory hammer or silent piler could further ameliorate the
residual impact. Given the nature of the
piling works, noise enclosure for covering the piling auger would not be a
practicable option. The use of
alternative piling method mentioned above has been considered but such method
could possibly cause local deformation and therefore was not recommended. Cranes and trucks would also be used during
piling. However, due to their mobile nature and spatial limitation, the use of movable
noise barriers and noise enclosures would not be feasible. It was considered
that all practicable mitigation measures have been exhausted and residual noise
impacts due to piling works have been minimised.
3.128
Another construction activity which would lead to the noise
exceedance would be demolition of the Centre Street Market West Block. Having
reviewed the
site conditions, concrete crusher instead of hydraulic
breaker has
been proposed for carrying out the demolition works at this
location. Noise impact resulted from the use of this
alternative demolition method would generally be lower than that from the use
of conventional method using hydraulic breakers.
3.129
A concrete corer would be needed in conjunction with the use
of concrete crusher. To mitigate the noise impact from this PME, a noise
enclosure which could achieve a noise reduction of 15dB(A) has
been proposed.
In addition, the practicality of using movable noise barrier during demolition
was also reviewed. Similar to other works area where demolition would take
place, placing movable noise barrier on top of the building to be demolished
would have construction safety issues. Practicable
mitigation
measures to further reduce the extent of residual impact
were not available.
3.130
The excavation process at this works area would also cause
the noise exceedance. To reduce the noise impact, a NIC has been proposed to
cover the opening of the shaft throughout the excavation process. Similar to
the situation in works area M3 – SYP Entrance C (Section 3.120 refers), the NIC could
reduce the noise emissions by about 20dB(A). PME operating outside the NIC including trucks
and crane would be mobile, and thus would not be possible to cover them by
using enclosure or movable barriers.
3.131
Similar to the situation in works
area M3 – SYP Entrance C, the use of trucks for station fitout would also
cause residual
noise impact. No
mitigation
measures could be provided due to the mobile nature of the trucks.
3.132
All practicable measures have
been exhausted and residual noise impacts that would arise from the execution
of works at this location have been minimised.
3.133
Residual impact would be predicted at NSRs SYP 11-13
surrounding this works area. Piling, excavation and construction activities that would take place in the
soft ground tunnel would be main reasons of the residual impact.
3.134
Similar to the situation in Works Area M1 - SYP Entrance B1
& B2, since the NSRs are in close proximity to the site boundary at which
piling would take place, and it would not be feasible to
use alternative
quieter piling method, piling would give rise to residual
impacts at the surrounding NSRs. The use of noise insulating fabric is considered to be the
only practicable mitigation measure to screen the noise from the piling auger.
Further reduction in noise levels
can be achieved by covering the piling equipment with a NIC. However, since this works area would
be extremely tight, space available for erecting the NIC would be
highly limited.
In particular, since this works area is highly congested, there would
not be sufficient space for providing the necessary foundation of the NIC.
3.135
In light of the predicted noise
exceedance, the
use of decking has been proposed to minimize the noise levels generated from
the construction activities in the soft ground tunnel. By
covering the opening of the shaft with a deck, a noise reduction of 20dB(A) can
be achieved. As mentioned in Section 3.70,
there would
not be any opening at the deck such that noise would not leak out from the
deck. As the soft ground tunnel is excavated, the excavated material would not
be transported out of the tunnel to ground level at this works area.
Instead, they will be transported to the
nearby mucking out shaft at
3.136
Because of the congested environment
of this works area, residual noise impacts have been minimised as far as
possible by deploying all available practicable mitigation measures. However measures to further ameliorate the
residual impacts could not be provided because of the tight environment of this
works area.
3.137
Minor residual impact would be
anticipated at NSRs GT5 and GT6, which are in proximity to this Works Area O3.
The noise exceedance would possibly be due to
the small
separation distance
between the impacted NSRs and the works area.
3.138
Drill rig and power rammer would be the nosiest PME used in
this works area. To reduce their associated noise impact, noise insulating
fabric has been proposed to screen the noise generated from them to the NSRs. Noise
reduction of 10dB(A) would be achieved with this mitigation measures in place.
3.139
Movable noise barrier and noise enclosure have also been
recommended where practical. With the use of all practicable noise mitigation
measures, the construction noise impact arising from this works area has been
minimized.
3.140
Residual noise impacts have been
minimised through exhausting all practicable direct noise mitigation measures
including the use of quieter plant, temporary / movable noise barriers, noise
enclosure/acoustic shed, “Noise Control Curtain”, silencers, noise insulating
fabric, noise insulating cover, acoustic enclosure and decking over the
excavation area / shaft as far as practicable.
Having reviewed the site constraints and nature of works to be undertaken
at various works areas, it is considered that all practicable mitigation
measures have been exhausted and residual impacts minimised.
3.141
Because of the close proximity to
the NSRs, further direct mitigation measures would not be practicable in
eliminating all construction noise exceedance.
Indirect Technical Remedies (ITR) is therefore considered for minimizing
the construction noise impacts.
3.142
It should be noted that the use
of ITR as a mitigation measure is neither a requirement stipulated under Annex
13 of the EIAO-TM nor the EIA Study Brief. The provision of ITR is the initiative of the Project
Proponent in view of the noise disturbance associated with the construction of
the WIL. ITR would generally require the
consideration to upgrade the glazing if necessary for the noise sensitive
facades exposed to excessive residual noise impact. The provision of air-conditioning would also
be considered for those affected dwellings.
3.143
With reference to the East Rail Extension Hung Hom to Tsim Sha
Tsui EIA Final Report (ERE-EIA Report), the eligibility criteria proposed
for qualifying NSRs for ITR would be dependent on the severity of the residual
noise impact and duration of exceedance after implementing all practical direct
mitigation measures. The eligibility criteria
set out in the ERE-EIA Report are:
i.
The affected household would be subject to a residual noise
impact of 5 dB(A) or above;
ii.
The duration of the residual noise impact at the building
façade of the household would be 1 month or more.
3.144
Based on the assessment results
presented in Appendix 3.4, residual
impacts which would be in excess of 5dB(A) and last for one month or more would
be predicted at NSRs located in the proximity of the following works areas:
i.
UNI Entrance B1
ii.
SYP Entrance A1 & A2
iii.
SYP Entrance B1 & B2
iv.
SYP Entrance B3
3.145
NSRs which would be considered
eligible for providing ITR as per the two criteria set out in the ERE-EIA are
listed in Table 3.14 below and
depicted in Figure 3.19 – 3.20.
Table 3.14 NSRs Eligible for the Provision of ITR
Works Area |
Locations |
Total no. of floors |
Estimated no. of affected dwellings per floor (with noise
exceedance>5dB(A)) |
No. of floors requiring ITR |
No. of dwellings requiring ITR |
UNI Entrance B1 |
|
10 |
2 |
4 |
8 |
SYP Entrance A1 & A2 |
Ngan Yu Building |
6 |
3 |
6 |
18 |
|
21 |
1 |
14 |
14 |
|
|
6 |
1 |
6 |
6 |
|
SYP Entrance B1 & B2 |
|
29 |
4 |
3 |
12 |
|
27 |
2 |
2 |
4 |
|
|
5 |
2 |
2 |
4 |
|
First Street No. 77 |
4 |
1 |
2 |
2 |
|
First Street No. 75 |
4 |
1 |
2 |
2 |
|
SYP Entrance B3 |
|
6 |
1 |
1 |
1 |
|
5 |
1 |
1 |
1 |
|
|
5 |
2 |
1 |
2 |
|
|
5 |
4 |
1 |
4 |
|
|
5 |
1 |
1 |
1 |
|
|
4 |
1 |
1 |
1 |
|
|
5 |
1 |
1 |
1 |
|
|
5 |
2 |
2 |
4 |
|
|
5 |
1 |
2 |
2 |
|
|
6 |
1 |
2 |
2 |
|
|
5 |
2 |
2 |
4 |
|
Chung Ching House |
5 |
4 |
2 |
8 |
|
|
5 |
1 |
2 |
2 |
|
|
8 |
3 |
2 |
6 |
|
Total no. of dwellings requiring ITR |
109 |
Notes: the number of affected dwellings per floor was
estimated based on information obtained from site visits conducted in October 2006.
3.146
No adverse operational residual
noise impact would be envisaged if the noise emissions from the proposed fixed
plant are designed to meet the Max SWL with appropriate noise reduction
measures in place.
3.147
An Environmental Monitoring and Audit (EM&A) programme
is recommended to be established according the predicted occurrence of noisy
activities. The recommended mitigation
measures should be implemented during construction
stage. Details of the programme are provided in a
stand-alone EM&A Manual.
3.148
Prior to the operation phase of
the Project, a commissioning test should be conducted to ensure compliance of
the operational airborne noise levels with the EIAO-TM noise criteria. Details of the EM&A programme are
provided in a stand-alone EM&A Manual.
3.149
Noise arising from the construction activities of the
project would have unavoidable potential impact on the NSRs located in the
vicinity of the works areas.
Unmitigated cumulative construction noise levels at the representative
NSRs are predicted, which are found to be in the range of 40 to 98 dB(A),
exceeding the EIAO-TM daytime construction noise limit by up to 23 dB(A).
3.150
Mitigation measures are recommended to reduce the noise
levels to within the EIAO-TM noise criterion, including good site practices, quieter plant,
silencer, movable noise barrier, temporary noise barrier, noise enclosure,
noise insulating fabric, “Noise Control Curtain”, acoustic enclosure, noise
insulating cover and decking over the excavation area/ shaft. With the recommended mitigation measures in
place, noise levels at most of the NSRs are
predicted to comply
with the EIAO-TM daytime construction noise criterion and no adverse residual
construction noise impact is expected. Some NSRs,
including KET3-5,
KET7, KET9, UNI1, UNI10-12, SYP1-5, SYP7-13, SYP16 and GT5-6 located in close
proximity to the works areas, would still be exposed to noise levels
exceeding the EIAO-TM noise criteria.
The ITR has been considered for minimizing the residual construction
noise impacts for these affected NSRs. The
provision of ITR is neither a requirement stipulated under Annex 13 of the
EIAO-TM nor the EIA Study Brief, and is the initiative of the Project Proponent
in view of the noise disturbance associated with the construction of the WIL. Based
on the criteria developed in the East
Rail Extension Hung Hom to Tsim Sha Tsui EIA Final Report (ERE-EIA), NSRs
which were considered to be eligible for ITR provision were identified.
3.151
Based on the current design,
there would be two ventilation fans operating in the magazine adit during
restricted hours, and would require the application of CNP under
the NCO. To
evaluate whether construction works in restricted hours are feasible,
preliminary construction noise impact assessment has been
carried out and the assessment results showed that with the implementation of
mitigation measures, the predicted noise level at the representative NSR would
comply with the NCO criteria. However, it should be noted that the assessment
result is indicative only and the Noise Control Authority will only consider an
application based on the NCO, the relevant technical memoranda issued under the
NCO, the contemporary condition/situations of adjoining land uses and any
previous complaints against construction activities at the site. The assessment
result in this EIA Report would not bind the Noise Control Authority in making
its decision in granting a CNP.
3.152
The assessment results indicated that predicted noise levels
at all NSRs arising from the fixed plant of the Project would comply with the
EIAO-TM criteria, with the noise emissions from the fixed plant controlled to
achieve the specified Max SWL by proper noise reduction measures. Thus, no adverse fixed plant noise impacts
would be expected.