8.1
Assessment on the potential dust impacts
associated with the construction phase of the Project is presented in this
section. Representative Air
Sensitive Receivers (ASRs) in the vicinity of the study area are
identified. The potential dust
impacts on these ASRs arising from dust emission from construction activities associated with the Project have been
assessed and appropriate mitigation measures are proposed to alleviate the
potential air quality impacts.
8.2
The train to be employed for the Shatin to
Central Link (SCL) will be electrically operated, air
quality impact associated with train emission is therefore not anticipated during operation phase. Exhausts for general ventilation and
smoke extraction facilities will also be carefully positioned to avoid causing
nuisance to the surrounding environment.
Thus, air quality impact during operation phase is considered
insignificant and will not be assessed in this section.
Environmental Legislation,
Standards and Guidelines
8.3
The criteria and guidelines for air quality
assessment are laid down in Annex 4 and Annex 12 of the Technical Memorandum on
Environmental Impact Assessment Process (EIAO-TM). In addition, specific requirements on
air quality assessment for this Project are stipulated in Clause
Air Quality Objectives & EIAO-TM
8.4
The Air Pollution Control Ordinance (APCO)
provides the statutory authority for controlling air pollutants from a variety
of sources. The Hong Kong Air
Quality Objectives (AQOs), which stipulate the maximum allowable concentrations
over specific periods for typical pollutants, should be met. The AQOs are
listed in Table 8.1.
Table 8.1
Pollutant |
Maximum
Concentration (µg/m3) (1) |
||||
Averaging
Time |
|||||
1 hour(2) |
8 hour(3) |
24 hour(3) |
3 month(4) |
Annual(4) |
|
- |
- |
260 |
- |
80 |
|
Respirable Suspended
Particulates (RSP) (5) |
- |
- |
180 |
- |
55 |
|
800 |
- |
350 |
- |
80 |
Nitrogen Dioxide
(NO2) |
300 |
- |
150 |
- |
80 |
Carbon Monoxide
(CO) |
30,000 |
10,000 |
- |
- |
- |
Photochemical
Oxidants (as Ozone, O3)
(6) |
240 |
- |
- |
- |
- |
Lead |
- |
- |
- |
1.5 |
|
Notes:
(1)
Measured at 25°C and one atmosphere .
(2)
Not to be exceeded more than three times per
year.
(3)
Not to be exceeded more than once per year.
(4)
Arithmetic mean.
(5)
Suspended particulates in air with a nominal aerodynamic
diameter of
(6)
Photochemical oxidants are determined by
measurement of ozone only.
8.5
The EIAO-TM stipulates that the hourly TSP
level should not exceed
Air Pollution Control (Construction Dust) Regulation
8.6
Notifiable and regulatory works are under the
control of Air Pollution Control (Construction Dust) Regulation. Notifiable works are site formation,
reclamation, demolition, foundation and superstructure construction for
buildings and road construction.
Regulatory works are building renovation, road opening and resurfacing,
slope stabilisation, and other activities including stockpiling, dusty material
handling, excavation, concrete production, etc. This Project is expected to include
notifiable works (foundation and superstructure construction as well as
reclamation) and regulatory works (temporary stockpile, dusty material
handling, excavation and concrete production). Contractors and site agents are required
to inform EPD and adopt dust reduction measures to minimize dust emission,
while carrying out construction works, to the acceptable level.
Air Pollution Control Ordinance – Control of Emissions from Specified Processes
8.7
A licence is required for the operation of
Cement Work (Concrete Batching Plant) under Part IV of APCO. Application for licence should be made
to EPD. EPD may either grant or
refuse to grant a licence subject to whether the applicant can fulfil the
environmental standards to avoid causing air pollution. If EPD decides to grant the licence, a
set of conditions will be imposed to prevent adverse impact from the discharge
of air pollutant emissions.
Description of the Environment
8.8
The Project alignment is an extension of the existing East Rail Line (EAL) from the
Hung Hom Station (HUH) across the harbour to new Exhibition Station (EXH) and
Admiralty Station (ADM). The
locality of the Project Area is a developed urban area with major land uses
including commercial,
residential and open spaces.
8.9
The study areas include both
Table 8.2 Background
Air Pollutant Concentrations adopted in this Assessment (
Urban
Stations |
Annual Average TSP Concentration
(μg/m3) |
TSP Background Concentration (μg/m3) |
||||
2006 |
2007 |
2008 |
2009 |
2010 |
||
82 |
79 |
67 |
63 |
63 |
70.8 |
|
Kwai Chung |
81 |
85 |
79 |
70 |
71 |
77.2 |
Sham Shui Po |
79 |
79 |
81 |
77 |
76 |
78.4 |
Kwun Tong |
75 |
82 |
72 |
70 |
67 |
73.2 |
Central/Western |
78 |
77 |
78 |
73 |
76 |
76.4 |
|
|
|
|
|
Average |
75.2 |
Note: Monitoring
results that exceeded AQO are shown in bold characters.
8.10
For
8.11
Central/Western
monitoring station is located at Sai Ying Pun at the centre of the hinterland
area. The monitoring station is
surrounded by mixture of commercial as well as densely populated residential
areas and busy local traffic networks in all directions. The TSP recorded at this station would
largely be contributed by the vehicular emissions from the surrounding road
network. On the contrary, the
study area of this Project at the
8.12
Central
Reclamation Phase III (CRIII) is a designated project under the EIA Ordinance
and its project site is located near the northern harbourfront of the
8.13
The air quality
monitoring at PLA commenced in April 2005 and data of up to 5 years are
available to represent the background air quality in the surrounding area. Whereas the air quality monitoring at
City Hall only commenced in March 2006 with less than 5 years available data at
the time of preparation of this assessment and thus is not selected for background
air quality estimation.
8.14
All the TSP
monitoring data were recorded in accordance with the requirements stipulated in
the EM&A Manual of CRIII and were reviewed and submitted as per the
requirements of the corresponding environmental permit issued under the EIA
Ordinance. All the TSP
levels were measured in accordance with the standard high volume sampling
method set out in the Title 40 of the Code of Federal Regulations, Chapter 1
(Part 50), Appendix B. Initial
calibration of dust monitoring equipment was conducted upon installation and
thereafter at bi-monthly intervals.
The transfer standard is traceable to the internationally recognised
primary standard and was calibrated annually. The calibration and air quality
monitoring was conducted by independent environmental team and led by an
environmental team leader. The
calibration data were also reviewed and validated by independent environmental
checker. The collected dust samples
were analysed by a laboratory which had been inspected and audited by the
independent environmental checker as per the EM&A Manual of CRIII Project
to undertake the dust analysis.
8.15
Review of the detailed TSP monitoring results
recorded at PLA was undertaken and it is observed that some unusually low TSP
concentrations were measured on some days.
TSP comprises of suspended particulates of different size including
respirable suspended particulates (RSP).
The background RSP level in Hong Kong is largely influenced by regional
contribution, thus the spatial variation of RSP level over the
8.16
The TSP data
recorded at PLA are considered as of acceptable quality and with sufficient
valid data after discarding the unusually low TSP monitoring data. The
estimated background TSP concentration for the study area at
8.17
For the offsite works area in Shek O, there is no EPD general air quality monitoring station located in the
vicinity of the study area. Since Shek O, in accordance with the Guidelines in
Assessing the ‘TOTAL’ Air Quality Impacts and Annual Air Quality Monitoring
Report, is categorized as rural area, the recent five years (2006 – 2010)
annual average monitoring data recorded for EPD’s general air quality
monitoring stations in rural areas are therefore taken to estimate the
background concentration.
EPD’s rural general air quality monitoring stations considered in this
assessment include Shatin, Tai Po and Tung Chung. The background TSP concentrations adopted in this assessment for Shek O area
is estimated as the mean of the annual average concentrations (2006 – 2010)
recorded at these rural monitoring stations and is equal to 66.4µg/m3.
8.18
In accordance with
Annex 12 of the EIAO-TM, any domestic premises, hotel, hostel, hospital,
clinic, nursery, temporary housing accommodation, school, educational
institution, office, factory, shop, shopping centre, place of public worship,
library, court of law, sports stadium or performing arts centre are considered
as air sensitive receivers (ASRs). As stated in the EIA Study Brief, the boundary of the assessment area
for air quality assessment should be 500m from the Project alignment and
boundaries of all associated areas under the Project. A total of 18 representative ASRs, which
are considered to be most likely to be affected by the construction of the
Project, have been identified for this assessment. The selected representative ASRs are
listed in Table 8.3 and their locations are illustrated in Figure Nos. NEX2213/C/331/ENS/M60/001
to NEX2213/C/331/ENS/M60/004.
8.19
The proposed
alignment would generally be built by cut-and-cover methods, drill and blast,
immersed tube (IMT) or soft ground Tunnel Boring Machines (TBMs). For the cut-and-cover section, some of
the associated construction works would be at ground level. Whereas for IMT, TBM or drill-and-blast
section, the works are mostly underground or underwater with minimal dust
emission.
8.20
The lowest
assessment height was therefore taken as either at 1.5m above local ground
level (AGL) which is the average height of the human breathing zone or at the
lowest height where the air sensitive use of the respective ASR locates. Higher assessment levels as shown in Table 8.3
were also selected for elevated ASRs to show the vertical variation of the
pollutant concentrations.
Table 8.3 Representative
Air Sensitive Receivers
ASRs |
Description |
Land Use |
Distance
from the nearest emission sources (m) |
No. Of
storey |
Assessment
Height (m
AGL) |
|
|||||
HHA6 |
|
Hotel |
50 |
11 |
1.5, 5, 10, 15
& 20 |
HHA7 |
Fire Service Headquarters |
GIC |
60 |
13 |
1.5, 5, 10, 15
& 20 |
HHA8 |
|
GIC |
35 |
1 |
10, 15 & 20 |
HHA9 |
Harbourfront Horizon (b) |
Service
Apartment |
20 |
22 |
5, 10, 15 &
20 |
Hong Kong Side |
|||||
CHA1 |
World Trade Centre (c) |
Commercial |
70 |
34 |
5, 10, 15 &
20 |
CHA2 |
|
Commercial |
35 |
33 |
5, 10, 15 &
20 |
EXA1 |
Causeway Centre Block A (c) |
Residential |
25 |
42 |
5, 10, 15 &
20 |
EXA2 |
Great Eagle centre (c) |
Commercial |
10 |
27 |
5, 10, 15 &
20 |
EXA3 |
Renaissance
Harbour View Hotel (c) |
Hotel |
15 |
46 |
10[2], 15 & 20 |
EXA4 |
|
Recreation |
25 |
NA |
5 |
EXA5 |
Existing Harbour Road Sports Centre and Wan
Chai Swimming Pool (would be demolished in 2015) (b) |
Government/Institution/ Community |
5 |
6 |
2, 5 & 10 |
EXA6 |
Wanchai Sports Ground |
Government/Institution/ Community |
20 |
NA |
1.5 |
EXA7 |
New Harbour Road Sports Centre and Wan Chai
Swimming Pool (would be in operation in 2015) (c) |
Government/Institution/ Community |
5 |
7 |
10, 15 & 20 |
ADA1 |
New G/IC site south and east of CITIC Tower |
Government/Institution/ Community |
160 |
20 |
1.5, 5, 10, 15
& 20 |
ADA2 |
Police Headquarters (Cain House) |
Government/Institution/ Community |
165 |
7 |
1.5, 5, 10, 15
& 20 |
ADA3 |
Admiralty Centre (c) |
Commercial |
320 |
25 |
5, 10, 15 &
20 |
ADA4 |
Police Headquarters (West Wing) |
Government/Institution/ Community |
300 |
42 |
1.5, 5, 10, 15
& 20 |
Off-site |
|||||
TWA1 |
To Tei Wan Village |
Residential |
310 |
2 |
1.5 |
Notes:
(a)
Hong Kong Coliseum is sitting on the podium
of HUH. The tunnel construction
works adjacent to this ASR will be carried out underneath the HUH podium. As such, the lowest assessment height
for this ASR is taken as 10m above the construction works.
(b)
The height of the
lowest air sensitive use was selected as the lowest assessment height of the
respective ASR.
(c)
The estimated
lowest fresh air intake location was selected as the lowest assessment height
of the respective ASR.
8.21
The Project is an approximately 6km extension of the existing EAL from the HUH across
the harbour to new EXH and ADM. HUH, EXH and ADM would become integrated
interchange stations with existing and planned lines.
8.22
The design and build of the new ADM and
8.23
Besides the construction of the railway
alignment, the Project includes the construction of new stations, construction of plant rooms ventilation shafts, some demolition
works and culvert/drain diversion. In addition, barging point locations are
proposed at Hung Hom Freight Pier on
8.24
Major construction works that would
contribute to dust impacts would include surface works for the construction of tunnel,
construction of superstructures
including the new stations, plant rooms and ventilation
shafts, as well as the operation of barging points. The tentative working hours will be from 07:00 –
19:00 from Monday to Saturday for all works sites including barging
points. Locations of the works
sites and barging points are illustrated in Figure Nos. NEX2213/C/331/ENS/M60/001 to NEX2213/C/331/ENS/M60/003. The details of construction activities and
potential emission sources are described in the following sections.
8.25
Alternative
construction methods/phasing programme were described in Chapter 2 of this
report.
8.26
The construction
for tunnels at Hung Hom area would be generally carried out by cut-and-cover method
near waterfront and Hung Hom Landfall.
The North Ventilation Building, Plant Rooms and Emergency Access (NOV)
which is located to the south of the Hung Hom podium and above the SCL running
tracks would also be constructed by cut-and-cover method. In addition, the existing
8.27
The cross-harbour
tunnels would be constructed using IMT and the section of tunnels within the
Causeway Bay Typhoon Shelter (CBTS) would be constructed by cut-and-cover
method involving temporary reclamation.
The South Ventilation Shafts, Plant Rooms and Emergency Access (SOV)
would also be constructed by cut-and-cover method. Tunnels from the SOV to ADM would be
constructed using TBM with a section between Hong Kong Convention and
Exhibition Centre (HKCEC) by cut-and-cover method, which would be reclaimed
under the Wan Chai Development Phase II (WDII) Project. The ADM overrun would be constructed by
drill-and-blast method.
8.28
For cross-harbour
tunnel construction using IMT method, the excavated materials would be wet or
the construction works would be carried out at seabed and no dust emission
would be expected.
8.29
For the
drill-and-blast section at ADM
overrun tunnel and TBM at
8.30
For those sections
using cut-and-cover method, construction would be conducted initially above
ground for installation of a deck.
Once the deck is installed, majority of the construction activities would
be underground below the deck. Therefore, the major potential dust impacts above ground would be dust arising from excavation,
material handlings and
transportation of spoils on the paved haul road within the site.
8.31
During excavation and unloading of spoils,
water spraying would be provided to alleviate potential dust emissions. All the trucks would be equipped with a
cover and the dusty materials would be well covered before leaving the works site area.
Therefore, adverse dust impact from the transportation of spoil would
not be anticipated. Wheel washing
facilities would be provided at every designated vehicle exit point. Since all vehicles would be washed at exit
points and all trucks loaded with dusty materials would be covered entirely
before leaving the works site, the
dust nuisance from construction vehicle movement outside the works site is
unlikely to be significant.
8.32
As mentioned in
Section 8.26, existing
Adits & Shafts and Ventilation Shafts
8.33
There are adits and shafts to be built along
the Project alignment for the operational tunnel ventilation. These adits and shafts are also used
during construction phase for providing access for delivery of tunnelling
equipment and permanent material and the removal of spoil (for sections of
Project alignment using TBM and drill-and-blast method).
8.34
The size of the construction area for each adit/shaft would be limited. After site clearance and open-cut
excavation at the surface area, the sheet piles/diaphragm wall would be
installed. Generally, the
tracked crane would be used for mucking out. Though mucking areas would
not be fully enclosed, water spraying would be provided during excavation and unloading of spoils, to
alleviate potential dust emissions.
All the trucks would be equipped with a cover and dusty materials would be well covered before
leaving the mucking-out areas. Moreover, as the excavation
is carried out below sea level, the excavated materials would mostly be slurry
with high moisture content. Therefore,
adverse dust impact from the transportation of spoil would not be anticipated.
8.35
An underground plant room, namely SOV, would be built by cut-and-cover method underneath the existing Police Officer’s Club
(POC) which is adjacent to the Cross Harbour Tunnel and CBTS. The existing POC facilities would be demolished to enable construction
of the SOV and tunnel structure. On
completion of the SCL construction, the POC would be reconstructed at its
current location and the SOV would be an integrated part of the reprovisioned
POC. A shaft would be
installed on top of the SOV to support the tunnel operation. The SOV is designed as simple reinforced
concrete structure with rooms to house the ventilation fans and support
systems. Potential dust impact
would be expected and would be assessed in this assessment.
8.36
An aboveground plant room, namely NOV would
be built at Hung Hom area. Some ventilation shafts would also be built at
the EXH for the
operational tunnel and station ventilation. However, the construction areas for NOV
and the ventilation shafts at EXH would be limited and are designed as
reinforced concrete structures.
Adverse dust impacts arising from construction of ventilation buildings
and ventilation shafts are not anticipated with the implementation of dust
suppression measures stipulated in Air Pollution Control (Construction Dust)
Regulation.
SCL Protection Works and Minimum Protection Works undertaken by WDII and Central Wanchai Bypass (CWB)
8.37
In accordance with the latest construction
programme, some construction works of SCL would be carried out at the CBTS
temporary reclamation area under CWB project and the HKCEC reclamation area
under WDII project. These
construction works would be carried out in advance and would not interface with
this Project.
SCL Protection Works at CBTS
8.38
For the SCL Protection Works at CBTS, the
construction works, which are to be undertaken by CWB project, would be advanced in 2012
and completed in 2013 before the commencement of this Project. The potential air quality impact
associated with the construction of the SCL Protection Works at CBTS was
assessed and presented in its EIA report.
As concluded in its EIA report, with the implementation of the
recommended mitigation measures as well as the dust suppression measures and
good site practices stipulated in the Air Pollution Control (Construction Dust)
Regulation, no adverse dust impact on the ASRs in the vicinity of the construction
sites would be anticipated.
Entrustment works next to HKCEC Phase I
8.39
The entrustment work at reclamation area of
HKCEC1 under WDII will also be carried out in advance in 2011/2012 for about
half year by WDII project. The
associated potential air quality impact was assessed in a stand-alone
Preliminary Environmental Report.
Works area of entrustment works would be around 0.1ha and would include
construction of D-walls and excavation up to +2mPD for construction of top
slab. No additional excavation
would be required for this protection works.
8.40
In view of the small scale and short-term
nature (last for 6 months) of the entrustment works, dust generation from the
excavation and backfilling works is considered limited. Since the entrustment works is laid
within the works area of the WDII project and the scale is limited, adverse
cumulative dust impacts on nearby ASRs (e.g. HKCEC,
Barging Point
8.41
There are two on- site barging points to be
provided for this Project, one is located on
8.42
The barging point
will operate for 12 hours a day (7:00 to 19:00) except the hoisting of Typhoon
No.3 or above, Sundays and public holidays. The spoil materials would be transported
to the tipping halls of the barging points by trucks and then unloaded to the
barges.
8.43
The haul roads
within the barging site would be all paved and provided with water
spraying. Vehicles would be
required to pass through designated wheel washing facilities before leaving the
barging facility. Moreover, the
dusty materials on the trucks would be well covered and
flexible dust curtain
would be provided at
the loading points (from barging point to the barges).
On-site Mooring Site
8.44
A public mooring site is located at
south-east side of CBTS for mooring of marine transports, such as boats,
vessels and also for
mooring yachts as temporary reprovisioning for the Royal Hong Kong Yacht
Club. No potential air quality
impact would be expected.
Other Construction Works
8.45
There are some
other associated construction works, including demolition works, pile removal,
stormwater drain and culvert diversion.
The potential dust impacts from these activities are localized and the
excavated areas are limited. Adverse
dust impacts from these construction
works are not anticipated with the implementation
of dust suppression measures stipulated in Air Pollution Control (Construction
Dust) Regulation.
Off-site Construction Works
8.46
An off-site
construction works area has been identified and discussed in Table 8.4. The location of the works
site is shown in Figure No. NEX2213/C/331/ENS/M50/025.
The location of
Table 8.4 Off-site
Construction Works Elements
Off-Sites |
Location |
Remark |
Possible Representative ASR |
|
|
Works site are
located at the previous Shek O Quarry.
The area is remote and assigned for previous quarrying activities
(also used as IMT casting basin for Airport Rail Line in the past). Making reference to the long-term quarrying
activities in the past, no adverse air quality impact would be anticipated. Besides, the
concrete would be loaded from the truck into the barge in “wet” form, no dust
would be generated in this process.
The potential dust impact would be only expected from the on-site haul
road. |
To Tei Wan Village |
A concrete batching
plant would be proposed on site.
Potential dust impact associated with the operation of the plant is
anticipated, but only daytime operation would be expected. |
To Tei Wan Village |
||
|
|
A barging point
would be proposed on site at either the quay (northwest of the site) or the
bund wall. As the quay is located
closer to the ASR as compared with the bund wall, unloading activities were
assumed at the quay to represent a worst-case assumption. Dusty activities will mainly be the unloading of
spoils from the barge. The spoils
will then be transferred to the concrete batching plant through enclosed
conveyor belt. No adverse dust
impact would be expected. |
To Tei Wan Village |
Cumulative Dust Impact from Other Concurrent Project
8.47
On
SCL (MKK – HUH)
8.48
SCL (MKK – HUH)
branches out from the existing East Rail tracks from the tunnel portal near Oi
Man Estate (Portal
SCL (TAW – HUH)
8.49
The SCL (TAW –
HUH) is an extension of Ma On Shan Line from the Tai Wai Station through the new
stations in the east Kowloon, namely Diamond Hill, Kai Tak, To Kwa Wan, Ma Tau
Wai, Ho Man Tin Stations and finally connecting the West Rail Line (WRL) at the
HUH. The section of the SCL (TAW –
HUH) alignment at Hung Hom would be constructed by cut-and-cover method. Potential dust impacts would be
expected. The detailed assessment
methodology is presented in the SCL (TAW – HUH) EIA report and it is also
summarized in Appendix 8.3.
KTE
8.50
The KTE alignment
which branches out from the existing Yau Ma Tei Station to the new Ho Man Tin
Station would be constructed by drill-and-blast and mine tunnelling
methods. The new Ho Man Tin Station
would be constructed by cut-and-cover method and potential dust impacts would
be expected. The detailed
assessment methodology is presented in the KTE EIA report and it is also
summarized in Appendix 8.4.
8.51
On
8.52
The major
construction works for WDII and CWB Project would be the construction of trunk
road and reclamation works. The
proposed trunk road runs from Central Interchange in Central Reclamation Phase
I through the Central Reclamation Phase III, WDII and CWB project areas, and
the Island Eastern Corridor Link (IECL) which provides connection from the
eastern portal of the CWB to the IECL.
8.53
Any above ground
construction activity arising from WDII and CWB that is located within 500m
from the Project boundary would be examined in this assessment. The assessment methodology extracted
from the WDII and CWB EIA report is summarized in Appendix 8.5.
Shek O (Off-site)
8.54
During the
construction phase of the Project, no concurrent project would be located
within 500m of the Project works area at Shek O and hence cumulative dust
impact would not be expected.
8.55
Referring to the above sections, potential
adverse dust impact would be expected from construction of cut-and-cover tunnel/station/adits/shafts, operation of the barging points and
concrete batching plant. Quantitative
assessment is therefore conducted for these activities. The potential dust emission sources
considered in the assessment are shown in Figures
No. NEX2213/C/331/ENS/M60/052 to NEX2213/C/331/ENS/M60/055 under
Appendix 8.7.
8.56
Regarding construction of plant rooms and ventilation shafts, loading and unloading of spoils at the
adits/shafts, no adverse
dust impact at nearby sensitive receivers would be expected due to limited
dusty construction activities.
Minor excavation works and spoil loading/unloading would all be
undertaken within enclosed structure.
With the implementation of dust suppression measures as stipulated in
Air Pollution Control (Construction Dust) Regulation, no adverse dust impacts
would be expected from these construction activities. Therefore, the potential dust impacts
arising from these works areas are addressed qualitatively in the study.
8.57
Limited dust impact from unloading of spoils
at the barging points would be expected with the installation of flexible dust
curtain at the loading point, covering of the inactive temporary stockpiles
areas, and water spraying on the active stockpiles area and haul roads. However, the barging point at Hung Hom
Freight Pier and Wan Chai Waterfront Promenade would
operate concurrently with other dusty construction activities within the 500m
study area. Quantitative
assessments are thus conducted to determine the cumulative dust impacts on the
nearby ASRs.
Emission Inventory
8.58
The principal source of air pollution during
the construction phase will be the dust generated from the dusty activities as
mentioned above. The impact of
fugitive dust sources on air quality depends upon the quantity as well as the
drift potential of the dust particles emitted into the atmosphere. Large dust particles (i.e. over 100 mm in diameter) will settle close to the
source and particles that are between 30 and 100 mm in diameter would likely undergo impeded
settling. The main dust impacts are
likely to arise from particles with less than 30 mm in diameter, which have a greater potential
to disperse over greater distance.
8.59
According to USEPA AP-42[3], construction dust particles are grouped
into various particle sizes. On
8.60
On
8.61
Predicted dust emissions are based on
emission factors from AP-42. The
major dusty construction activities for the Project to be considered in the
modelling assessment include:
(A)
Tunnel, Station, Plant Rooms and Ventilation Shafts Cut-and-Cover areas
-
Excavation and
material handlings within the construction site modelled as heavy construction
activities
-
Wind erosion of
open active site
(B)
Barging Points
-
Transportation of
the spoils to the enclosed tipping hall of Barging Point by trucks on the paved
haul roads
-
Unloading point to
the barge
(C)
Concrete Batching Plant at
-
Unloading of
aggregates to the receiving hopper
-
Emissions from
dust collectors at the top of the large capacity cement silos, cement/PFA silos
and mixers
-
Transporting of
raw materials/products by trucks on the unpaved haul roads within the plant
8.62
According to the engineering design
information, dust control measures have been incorporated into the design of
the barging facilities, as presented in Table 8.5. These dust control measures have also
been taken into account in the assessment.
Table
8.5 Barging
Facilities– Dust Emission Design Control Measures
Process |
Description |
Dust
Emission Design Control Measures |
Haul road within barging facilities |
Transportation of spoils to the Barging Point |
All road surfaces within the barging
facilities would be paved and watering once along the haul road for every
working hour would be provided. |
Unloading of materials |
Unloading of spoil materials |
The unloading process would be undertaken
within a 3-sided screen with top tipping hall. Water spraying and flexible dust
curtains would be provided at the discharge point for dust suppression. |
Trucks |
Vehicles leaving the barging facility |
Vehicles would be required to pass through
the wheel washing facilities provided at site exit. |
8.63
The maximum production capacity of the
concrete batching plant would be 250 m3 per hour and the total
capacity of silo exceeds 50 tonnes and in which cement is handled. The operation of the concrete batching
plant is therefore classified as Specified Process (SP). The Contractor should apply a SP license
under APCO. The requirements and
mitigation measures stipulated in the Guidance
Note on the Best Practicable Means for Cement Works (Concrete Batching Plant)
BPM 3/2(93) should be followed and implemented. According to the above Guidance Note,
the design emission concentrations of the dust collectors for cement/
Pulverised Fuel Ash (PFA) silos and mixers of the concrete batching plant
should not exceed 50 mg/m3.
The dust control measures as stipulated in the above Guidance Note have
been incorporated into the design of the concrete batching plant as presented
in Table 8.6. These dust control measures have also
been taken into account in the assessment.
Table
8.6 Concrete
Batching Plant – Dust Emission Design Control Measures
Process |
Description |
Dust
Emission Design Control Measures |
Loading of raw materials |
Unloading of aggregates from the tipper
trucks to receiving hopper |
The aggregates would be unloaded from the tipper
trucks to the receiving hopper equipped with enclosures on 3 sides and top
cover, and water spraying system.
Minimal dust emission would be generated during unloading of the raw
materials. |
|
Unloading of cement and PFA from tankers into
the silo |
The cement and PFA would be directly loaded
into the silo via a flexible duct.
Dust collectors would be installed at cement/PFA silos, therefore, no
dust emission would be expected. |
Storage of raw materials |
Storage of aggregates in overhead storage
bins |
The aggregates would be stored in fully
enclosed overhead storage bins.
The top of overhead storage bins would be covered with cladding. Water spraying system would be
installed at the top of storage bins for watering the aggregates, and
aggregates storage bins would be fully enclosed. Thus, no dust emission would be
expected. |
Batching of raw materials |
Weighing and batching of cementitious
materials |
The whole process of weighing and mixing would
be performed in a fully enclosed environment. The mixers would all equip with dust
collectors, no dust emission would be expected. |
Truck loading |
Loading of concrete from mixer into transit
mixer of a truck |
The concrete would be directly loaded from
the mixer into the transit mixer of a truck in “wet” form, no dust would be
generated in this process. |
Trucks |
Tipper trucks and cement tankers leaving the Concrete
Batching Plant |
Haul road within the site is unpaved. Wheel washing pit would be installed
at the gate of the concrete batching plant. Insignificant dust emission would be
expected. |
Unpaved haul road within the Concrete
Batching Plant |
Transportation of materials within the plant |
Watering twice a day would be provided
(standard mitigation measure as stipulated in the Air Pollution Control
(Construction Dust) Regulation). |
8.64
Due to the constrained size of the works
sites and the tight construction programme, it will be necessary for active
construction activities to be undertaken at multiple work faces spread across
each site. Therefore, it is not
feasible to identify the exact location of individual dust emission source. As such, for the purpose of predicting
annual TSP concentrations, it is assumed that dust emissions would be
distributed across the whole area of each site and the dust emission rates are
estimated based on the annual average percentage active works area of each
works site. Based on the
preliminary engineering design, the annual average active area is estimated to
be 6% and would be assumed for predicting the annual average
concentrations. The justification
for the percentage of annual average active area is presented in Appendix 8.6a. However, for both the on-site and
off-site barging points haul road areas, it is assumed that the barging point
would be working at full capacity and a continuous use of the haul road
throughout the construction period would be taken as a worst-case
assumption. Thus, 100% emission
from the barging point haul road areas is assumed in the model.
8.65
Whereas for predicting hourly and daily
average TSP levels, it is assumed that 20% of the total works area of each site
would be active at any one time. As
mentioned above, it is not feasible to identify the exact locations of
individual dust emission source. As
such, the dust modelling assessment has assumed that the dust emissions would
be distributed across the whole area of each site to reasonably represent this
mode of construction activities.
8.66
Based upon the above, works activities and
plant would not be concentrated in certain areas of the site close to ASRs for
an extended period of time during the construction period. However, notwithstanding that such a
scenario would not be expected to occur, a hypothetical Tier 1 screening test
assuming 100% active area of construction site of the Project with mitigation
measures in place has been undertaken.
It aims to highlight the hot spot locations where construction dust may
potentially become an issue.
However, it should be emphasized that Tier 1 screening test is a
hypothetical one which is very conservative and does not occur in reality.
8.67
The Tier 1 results have allowed a more
focused Tier 2 assessment to be undertaken at the specific hot spot locations
where TSP non-compliance is predicted under the Tier 1 screening test. A focused Tier 2 assessment was
undertaken whereby the % daily maximum active works areas, which is assumed to
be 20% - 40%, for the Project are positioned closest to the potentially worst
affected ASRs. Same as for
predicting annual average TSP levels, 100% emission from the barging point haul
road areas is assumed in the model.
The Tier 2 assessment is also a very conservative approach as it assumed
20% - 40% active area of the Project would be located closest to the
potentially worst affected ASRs at any one time and that the barging point
would be working at full capacity throughout the construction period which is
unlikely to occur in reality. The
justification for the percentage of hourly and daily average active area is
presented in Appendix
8.6b.
8.68
The excavation rate, material handling rate, percentage
active area, moisture content, silt content, number of trucks and truck speed
are based on the preliminary engineering design. The emission rate of identified
pollutant sources are summarised in Table 8.7. Detailed calculations of the emission
factors are given in Appendix 8.7.
Table 8.7 Emission
Factors for Dusty Construction Activities
Emission Source |
Activity |
Emission Rate |
Remarks |
|
|
|
|
Tunnel Construction at Hung Hom Landfall |
Heavy
Construction Activities |
E=2.69 Mg/hectare /month of
activity |
100%
area actively operating
(for hourly and daily concentration prediction)
6% area
actively operating (for annual concentration prediction)
AP42,
Section 13.2.3 |
|
Wind
Erosion |
E=0.85Mg/hectare /year |
100%
area actively operating
(for hourly and daily concentration prediction)
6% area
actively operating (for annual concentration prediction)
AP42,
Section 11.9, Table 11.9.4 |
|
|||
Tunnel
Construction and Construction of SOV / New EXH and Launching
Shafts (Cut-and-Cover Areas) |
Heavy
Construction Activities |
E=2.69 Mg/hectare /month of activity |
100%
area actively operating
(for Tier 1 hourly and daily concentration prediction)
20%
area actively operating
(for Tier 2 hourly and daily concentration prediction)
6% area
actively operating (for annual concentration prediction)
AP42,
Section 13.2.3 |
|
Wind
Erosion |
E=0.85Mg/hectare /year |
100%
area actively operating
(for Tier 1 hourly and daily concentration prediction)
20% area
actively operating (for Tier 2 hourly and daily concentration prediction)
6% area actively operating (for
annual concentration prediction)
AP42, Section 11.9.4 |
Barging Point at Wan Chai Waterfront Promenade |
Unloading of spoils to barge |
E = k x (0.0016) x [(U/2.2)1.3 / (M/2)1.4] |
AP-42,
S13.2.4, particle size < 30 um, 1/95 ed
AP-42, Table 13.2.4-1, 1/95 ed
Handling capacity: 2500Mg/day Number of berth: 1 |
|
Paved haul road –Transport the spoil from the
stockpile to the Barging Point and potential temporary stockpile (Modelled as
Heavy Construction) |
E=2.69 Mg/hectare /month of activity |
100%
area actively operating
AP42,
Section 13.2.3 |
Shek O (Off-site) |
|||
Concrete Batching
Plant at |
Unloading of aggregates to the
receiving hopper of concrete batching plant |
E=0.0064lb/yd3 |
AP42
Section 11.12, (aggregate transfer)
Max. loading rate of aggregate =
250m3/hr |
|
Dust collector for each cement/PFA
silo/mixer |
E=50mg/m3 |
Design
emission concentration of 50mg/m3
Exhaust
rate for dust collector: 1780m3/hr
Number
of silos/mixer: 6 |
|
Heavy Construction Activities |
E=2.69
Mg/hectare /month
of activity |
100%
area actively operating
(for Tier 1 hourly and daily concentration prediction)
40%
area actively operating (for Tier 2 hourly and daily concentration
prediction)
40% area actively operating (for annual
concentration prediction)
AP42,
Section 13.2.3 |
|
Wind
Erosion (night time) |
E=0.85Mg/hectare /year =8.086 x 10-7 g/m2/s |
100%
area actively operating
(for Tier 1 hourly and daily concentration prediction)
40%
area actively operating (for Tier 2 hourly and daily concentration
prediction)
40% area actively operating (for annual
concentration prediction)
AP42,
Section 11.9.4 |
Barging Point at |
Unloading of spoils to barge |
E = k x (0.0016) x [(U/2.2)1.3
/ (M/2)1.4] |
AP-42,
S13.2.4, particle size < 30 um, 1/95 ed
AP-42, Table 13.2.4-1, 1/95 ed
Handling capacity for each barging
point: 4000Mg/day
Number
of berth: 1 |
8.69
Twelve working hours per day on normal
working days was assumed for the above-mentioned construction activities during
07:00 to 19:00 in the assessment.
8.70
According to the updated information
presented in the Environmental Permit of WDII & CWB Project, the
construction period of the whole WDII & CWB project is from 2009 to
2017. It is expected that the construction
of this Project would be only concurrently with the construction of WDII
Project after 2013. The hourly and
daily dust impacts arising from the construction of WDII & CWB in mid 2013
to early 2014 (namely scenario 1 in this assessment), mid 2014 to early 2015
(namely scenario 2 in this assessment) and mid 2015 to 2017 (namely scenario 3
in this assessment) were predicted and presented in the approved WDII & CWB
EIA Report.
8.71
However, annual average TSP concentrations
were not predicted in the WDII & CWB EIA. The annual TSP impact is therefore
assessed by assuming an annual average active area of 6% calculated based on
the available construction programme and plant inventory of WDII & CWB EIA
Report. The justification for the
percentage of annual average active area is presented in Appendix 8.6c.
8.72
With reference to
the proposed construction method of WDII and CWB, temporary seawall
construction will be first conducted to enclose each phase of the temporary
reclamation. Installation of
diaphragm wall on temporary reclamation land as well as any bulk filling will
proceed behind the completed seawall.
After the temporary reclaimed land was formed, tunnel box construction by
cut-and-cover method down to below water level will be conducted. Then all construction works would be
carried out below water level and adverse dust impact would not be
anticipated. Finally, the temporary
reclamation will be removed after completion of all tunnel construction
works. According to the assumption
made under WDII & CWB EIA, the maximum percentage of active construction
works area is 50%, the remaining 50% of the works area is just exposed to air
without any construction works.
Therefore, as the worst-case assumption, the annual exposed area is
assumed to be 50% for predicting the annual concentrations. Detailed calculations of the emission
factors are presented in Appendix 8.5. The major dusty construction activities
during construction of WDII from year 2013 to 2017 which interfacing with the
Project were extracted from WDII EIA Report Table 3.6 and its EP, EP-356/2009
as follows:
Table 8.8 Different
Major Dust Generating Activities in the Worst Scenarios during Construction
Phase of WDII
Activities |
Scenario 1 (namely Scenario 4 in WDII EIA report) |
Scenario 2 (namely Scenario 5 in WDII EIA report) |
Scenario 3 (namely Scenario 6 in WDII EIA report) |
1 |
TCBR3 –
CWB Tunnel |
TCBR3 –
CWB Tunnel |
TCBR4 –
CWB Tunnel |
2 |
TCBR4 –
Filling |
TCBR4 –
CWB Tunnel |
TPCWAW –
CWB Tunnel |
3 |
TPCWAW –
CWB Tunnel |
Slip Rd
8 & Victoria Park Reprovisioning |
Realignment
|
4 |
WCR2 –
Promenade |
TPCWAW –
CWB Tunnel |
Rd P2
from |
5 |
WCR3 –
Filling |
WCR3 –
CWB Tunnel |
Mainline
to IEC |
6 |
WCR4 –
Filling |
WCR4 –
CWB Tunnel |
|
7 |
WCR4 –
Drainage |
HKCEC2E
– Drainage |
|
8 |
HKCEC2W
– CWB Tunnel |
HKCEC2W
– Drainage |
|
9 |
HKCEC3W
– CWB Tunnel |
HKCEC2E
– CWB Tunnel |
|
10 |
HKCEC3E
– CWB Tunnel |
HKCEC2W
– CWB Tunnel |
|
11 |
IEC
Connection Work |
HKCEC3E
– CWB Tunnel |
|
12 |
|
HKCEC3W
– CWB Tunnel |
|
8.73
According to the construction programme (Appendix 3.4), the major dusty activities of this Project which would be
undertaken concurrently during the above three periods have been identified in
order to conduct the cumulative impact assessment. As the construction of this Project
would be undertaken from mid 2013 to 2020, the worst assessment year during
this period would be taken as the year having the maximum number of
construction activities. The
concurrent major dusty construction activities during different worst
construction periods are summarized below:
Table 8.9 Major
Dust Generating Activities during Different Construction Periods
Period |
Mid 2013 – Early 2014 |
Mid 2014 – Early 2015 |
Worst Assessment Year between Mid 2015 –
2020 |
Activities |
Scenario 1 |
Scenario 2 |
Scenario 3 |
1 |
Barging point at Wan Chai Waterfront
Promenade |
Barging point at Wan Chai Waterfront
Promenade |
Barging point at Wan Chai Waterfront
Promenade |
2 |
Launching Shaft Construction at |
Launching Shaft Construction at |
Launching Shaft Construction at |
3 |
EXH Construction at PTI Area |
EXH Construction at PTI Area |
EXH Construction at PTI Area |
4 |
|
EXH Construction at Wan Chai Sport Ground |
EXH Construction at Wan Chai Sport Ground |
5 |
|
Tunnel Construction West of EXH |
Tunnel Construction West of EXH |
6 |
|
SOV Construction |
SOV Construction |
7 |
|
|
Tunnel Construction at CBTS (outside
breakwater) |
8 |
|
|
Tunnel Construction at CBTS (inside
breakwater) |
9 |
|
|
EXH Station Construction at |
10 |
|
|
EXH Station Construction at |
Dispersion Modelling & Concentration Calculation
8.74
Fugitive Dust Model (FDM) (1993 version) was
adopted to assess potential dust impact from the construction works. The heights of 1.5m or the lowest air
sensitive level, 5m, 10m, 15m and 20m above ground were adopted for the
construction dust impact assessment.
8.75
Hourly
meteorological data including wind speed, wind direction, air temperature and
Pasquill stability class from the nearest Hong Kong Observatory weather station,
Hong Kong Observatory Station, for the year 2008, were employed for the model
run in
8.76
Whereas, the worst
case meteorological condition was used to predict the maximum hourly and daily
average TSP concentrations at representative discrete ASRs in the vicinity of
the construction sites at Hong Kong Island side.
·
Wind direction: 360
wind directions (1 degree resolution)
·
Resolution: 1°
·
Stability class: D (daytime, 8:00-18:00) & F (night time,
18:00-8:00)
·
Surface roughness: 1m
8.77
In order to
calculate the cumulative pollutant concentrations from this Project and WDII
& CWB project, the dispersion model was undertaken based on the above worst
case meteorological conditions. The
cumulative pollutant concentrations at the ASRs under each specific wind
direction were calculated by summing the results from the same scenario of this
Project and WDII & CWB
project. The highest pollutant
concentrations at the ASRs amongst the 360 wind directions were identified as the
worst predicted cumulative pollutant concentrations.
8.78
Daily TSP concentrations were calculated as
follows:
Daily TSP concentration = (number of daytime working hour)/24 ´ (1-hour average maximum TSP concentration predicted during daytime
working hours) + (number of night time working hour)/24 ´ (1-hour average maximum TSP concentration predicted during night time
working hours) + (number of non-working hour)/24 ´ (1-hour average maximum TSP concentration predicted during non-working
hours) + Background concentration
8.79
For prediction of
the annual TSP concentrations due to the Project, hourly meteorological data
including wind speed, wind direction, air temperature and Pasquill stability
class from the nearest Hong Kong Observatory weather station, Hong Kong
Observatory Station, for the year 2008, were employed for the model run.
8.80
For prediction of the hourly, daily and
annual TSP concentrations at Shek O, hourly
meteorological data including wind speed, wind direction, air temperature and
Pasquill stability class from the nearest Hong Kong Observatory weather
station, Stanley Station, for the year 2008, were employed for the model run.
8.81
Since no
construction activities would occur on Sundays and the public holidays, only
wind erosion would be assumed for these days as well as for other non-working
hours (19:00 to 0700 of the following day) on normal working days.
8.82
As mentioned in Section 8.9 - 8.17, the background TSP levels of 75.2 mg/m3 and
73.0 mg/m3
were adopted as the future TSP background concentration on
8.83
For the off-site construction works at
Level of Uncertainty in the Assessment
8.84
The emission rates adopted in the
construction dust impact assessment are in accordance with the USEPA AP-4),
which had previously been applied in similar situations in other EIA studies in
8.85
The Fugitive Dust Model (FDM) for
construction dust impact assessment is an accepted model for use in assessing
construction dust impacts with reference to EPD’s Guidelines on Choice of
Models and Model Parameters.
8.86
There are some modelling limitations such as
the accuracy of the plant inventory for the proposed construction works,
sequences of construction activities, and assessment height limit of 20m in the
adopted dust model. Uncertainties
in the assessment of impacts have been considered when drawing conclusion from
the assessment.
Prediction and Evaluation of Impacts
Unmitigated Scenario
8.87
The predicted unmitigated cumulative maximum hourly, daily and annual average TSP concentrations at the
representative ASRs are summarized in Tables 8.10
– 8.12 and detailed in Appendix 8.8.
The contour plots at 1.5m AGL are presented in Figure Nos. NEX2213/C/331/ENS/M60/063
- NEX2213/C/331/ENS/M60/077.
Table 8.10 Predicted
Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at
Representative Air Sensitive Receivers (Unmitigated) (
ASRs |
Assessment
Height (mAGL) |
Cumulative Maximum
TSP Concentrations
in mg/m3 |
||
Hourly Average |
24-hour Average |
Annual Average |
||
HHA6 |
1.5 |
648 |
149 |
76.6 |
|
5 |
612 |
144 |
76.5 |
|
10 |
426 |
125 |
76.2 |
|
15 |
236 |
106 |
76.0 |
|
20 |
181 |
97 |
75.8 |
HHA7 |
1.5 |
481 |
242 |
79.2 |
|
5 |
395 |
214 |
79.1 |
|
10 |
252 |
147 |
78.3 |
|
15 |
203 |
107 |
77.5 |
|
20 |
161 |
101 |
76.8 |
HHA8 |
10 |
394 |
127 |
75.9 |
|
15 |
254 |
108 |
75.8 |
|
20 |
194 |
96 |
75.7 |
HHA9 |
5 |
357 |
168 |
78.3 |
|
10 |
240 |
132 |
77.0 |
|
15 |
193 |
110 |
76.4 |
|
20 |
160 |
99 |
76.1 |
Note: (1) The background TSP
level of 75.2 mg/m3 is included in the
above results.
(2) The hourly, daily and annual average TSP EIAO-TM/AQO
criteria are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.
(3) Boldfaced values represent the
predicted TSP concentration exceeds the respective criteria.
Table 8.11 Predicted
Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at
Representative Air Sensitive Receivers (Unmitigated) (
ASRs |
Assessment
Height (mAGL) |
Cumulative
Maximum TSP Concentrations
in mg/m3 |
||
Hourly Average |
24-hour Average |
Annual Average |
||
CHA1 |
5 |
1357 |
634 |
77.0 |
|
10 |
800 |
432 |
75.8 |
|
15 |
582 |
293 |
75.0 |
|
20 |
446 |
227 |
74.4 |
CHA2 |
5 |
1774 |
809 |
78.4 |
|
10 |
919 |
494 |
76.2 |
|
15 |
645 |
322 |
75.1 |
|
20 |
486 |
224 |
74.4 |
EXA1 |
5 |
1605 |
668 |
79.0 |
|
10 |
896 |
480 |
76.5 |
|
15 |
635 |
334 |
75.4 |
|
20 |
440 |
243 |
74.7 |
EXA2 |
5 |
2355 |
1099 |
83.5 |
|
10 |
1154 |
601 |
78.2 |
|
15 |
716 |
375 |
76.2 |
|
20 |
479 |
260 |
75.3 |
EXA3 |
10 |
1408 |
734 |
81.4 |
|
15 |
892 |
459 |
78.2 |
|
20 |
591 |
311 |
76.5 |
EXA4 |
5 |
2099 |
684 |
81.4 |
EXA5 |
2 |
3118 |
1319 |
97.2 |
|
5 |
2206 |
864 |
85.6 |
|
10 |
1112 |
591 |
79.8 |
|
15 |
761 |
397 |
77.4 |
|
20 |
517 |
276 |
76.1 |
EXA6 |
1.5 |
5593 |
1884 |
89.5 |
EXA7 |
10 |
1298 |
676 |
78.1 |
|
15 |
798 |
412 |
76.2 |
|
20 |
514 |
273 |
75.2 |
ADA1 |
1.5 |
946 |
292 |
75.6 |
|
5 |
965 |
301 |
75.6 |
|
10 |
828 |
282 |
75.2 |
|
15 |
672 |
259 |
74.8 |
|
20 |
525 |
235 |
74.5 |
ADA2 |
1.5 |
763 |
265 |
75.3 |
|
5 |
789 |
275 |
75.3 |
|
10 |
697 |
260 |
74.9 |
|
15 |
586 |
242 |
74.5 |
|
20 |
470 |
222 |
74.2 |
ADA3 |
5 |
678 |
225 |
74.4 |
|
10 |
615 |
216 |
74.3 |
|
15 |
536 |
205 |
74.1 |
|
20 |
452 |
193 |
74.0 |
ADA4 |
1.5 |
619 |
220 |
74.5 |
|
5 |
647 |
229 |
74.5 |
|
10 |
587 |
220 |
74.4 |
|
15 |
510 |
208 |
74.1 |
|
20 |
428 |
195 |
73.9 |
Note: (1) The background TSP
level of 73.0 mg/m3 is included in the
above results.
(2) The hourly, daily and annual average TSP EIAO-TM/AQO criteria
are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.
(3) Boldfaced values represent the predicted TSP
concentration exceeds the respective criteria.
Table 8.12 Predicted
Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative
Air Sensitive Receivers (Unmitigated) (
ASRs |
Maximum Hourly Average TSP
Concentrations in mg/m3 |
Maximum Daily Average TSP
Concentrations in mg/m3 |
Annual Average TSP
Concentrations in mg/m3 |
TWA1 (at 1.5m AGL) |
1920 |
402 |
70.2 |
Note: (1)
The
background TSP level of 66.4 mg/m3 has
been included in the above results.
(2) The hourly
average TSP EIAO-TM criterion: 500 mg/m3; the daily average
TSP AQO criterion: 260
mg/m3; the annual average TSP AQO criterion: 80 mg/m3
(3) Boldfaced values represent the predicted TSP
concentration exceeds the respective criteria.
8.88
Based on the
results shown in Tables 8.10 - 8.12 above, the predicted
cumulative maximum hourly, daily and annual average TSP concentrations at most
of the representative ASRs would exceed the criteria stipulated in EIAO-TM and
AQO under unmitigated scenario.
Hence, proper dust mitigation measures should be implemented.
Recommended Air Quality Mitigation Measures
Watering
once every working hour on active works areas, exposed areas and paved haul
roads to reduce dust emission by 91.7%[4]. This dust suppression efficiency is derived based on the
average haul road traffic, average evaporation rate and an assumed application
intensity of 1.7 L/m2 for Kowloon side and 1.0 L/m2 for
Hong Kong side once every working hour. Any potential dust impact and watering
mitigation would be subject to the actual site condition. For example, a construction activity
that produces inherently wet conditions or in cases under rainy weather, the
above water application intensity may not be unreservedly applied. While the above watering frequency is to
be followed, the extent of watering may vary depending on actual site
conditions but should be sufficient to maintain an equivalent intensity of no
less than 1.7 L/m2 for Kowloon side and 1.0 L/m2 for Hong
Kong side to achieve the removal efficiency. The dust levels would be monitored
and managed under an EM&A programme as specified in the EM&A Manual.
Enclosing
the unloading process at barging point by a 3-sided screen with top tipping
hall, provision of water spraying and flexible dust curtains to reduce dust
emission by 50%[5].
Use of
regular watering to reduce dust emissions from exposed site surfaces and
unpaved roads, particularly during dry weather.
Use of
frequent watering for particularly dusty construction areas and areas close to
ASRs.
Side
enclosure and covering of any aggregate or dusty material storage piles to
reduce emissions. Where this is not
practicable owing to frequent usage, watering shall be applied to aggregate
fines.
Open
stockpiles shall be avoided or covered.
Where possible, prevent placing dusty material storage piles near ASRs.
Tarpaulin
covering of all dusty vehicle loads transported to, from and between site
locations.
Establishment
and use of vehicle wheel and body washing facilities at the exit points of the
site.
Provision
of wind shield and dust extraction units or similar dust mitigation measures at
the loading area of barging point, and use of water sprinklers at the loading
area where dust generation is likely during the loading process of loose
material, particularly in dry seasons/ periods.
Provision of not less than 2.4m high hoarding from ground level along
site boundary where adjoins a road, streets or other accessible to the public
except for a site entrance or exit.
Imposition
of speed controls for vehicles on site haul roads.
Where
possible, routing of vehicles and positioning of construction plant should be
at the maximum possible distance from ASRs.
Every
stock of more than 20 bags of cement or dry pulverised fuel ash (PFA) should be
covered entirely by impervious sheeting or placed in an area sheltered on the
top and the 3 sides.
Instigation of an environmental monitoring and auditing program to
monitor the construction process in order to enforce controls and modify method
of work if dusty conditions arise.
Mitigated Scenario
8.91
The predicted mitigated cumulative maximum
hourly, daily and annual average TSP concentrations at the representative ASRs
during construction are summarized in Table 8.13.
Table 8.13 Predicted Cumulative
Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative
Air Sensitive Receivers (Mitigated) (Kowloon Side)
ASRs |
Assessment
Height (mAGL) |
Cumulative
Maximum TSP Concentrations
in mg/m3 |
||
Hourly Average |
24-hour Average |
Annual Average |
||
HHA6 |
1.5 |
213 |
113 |
76.5 |
|
5 |
242 |
113 |
76.4 |
|
10 |
231 |
108 |
76.1 |
|
15 |
153 |
102 |
75.9 |
|
20 |
143 |
97 |
75.7 |
HHA7 |
1.5 |
195 |
112 |
78.1 |
|
5 |
192 |
111 |
78.0 |
|
10 |
178 |
108 |
77.5 |
|
15 |
163 |
104 |
77.0 |
|
20 |
153 |
101 |
76.6 |
HHA8 |
10 |
196 |
104 |
75.9 |
|
15 |
161 |
100 |
75.7 |
|
20 |
145 |
96 |
75.6 |
HHA9 |
5 |
201 |
105 |
77.9 |
|
10 |
168 |
102 |
76.7 |
|
15 |
143 |
98 |
76.2 |
|
20 |
137 |
95 |
75.9 |
Note: (1) The background TSP
level of 75.2 mg/m3 is included in the
above results.
(2) The hourly, daily and annual average TSP EIAO-TM/AQO criteria
are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.
8.92
Based on the
results shown in Table 8.13, the cumulative maximum hourly, daily and annual average TSP levels at
all ASRs would comply with the criteria stipulated in EIAO-TM and AQO after
implementation of the proposed dust mitigation measures. The worst-hit level would be at 1.5m AGL
at most ASRs. The contour plots of
cumulative maximum hourly, daily and annual average TSP concentrations at 1.5m
AGL are presented in Figure Nos. NEX2213/C/331/ENS/M60/005 - NEX2213/C/331/ENS/M60/007. As
there is no air sensitive use at the ground level of Harbourfront Horizon
(HHA9), the highest cumulative TSP
concentration is predicted at 5mAGL.
Contour plots of cumulative maximum hourly, daily and annual average TSP
concentration at HHA9 (5mAGL) is presented in Figure No. NEX2213/C/331/ENS/M60/008, NEX2213/C/331/ENS/M60/061 - 062. Some exceedance of hourly, daily and
annual average TSP concentrations were predicted at the north of the HUH and
the freight pier in the contour plots, however, there is no air sensitive use
at these areas and no adverse impact is anticipated.
8.93
The predicted mitigated cumulative maximum hourly and daily average TSP concentrations amongst the three
assessment scenarios of Tier 1 screening test at the
representative ASRs during construction are summarized in Tables 8.14 – 8.15. The detailed assessment results are
presented in Appendix 8.8. The Tier 1 contour plots of cumulative
maximum hourly and daily average TSP concentrations at 1.5m AGL are presented
in Figure Nos. NEX2213/C/331/ENS/M60/009
- NEX2213/C/331/ENS/M60/014.
Table 8.14 Predicted
Cumulative Maximum Hourly Average TSP Concentrations at Representative Air
Sensitive Receivers (Tier 1 – Mitigated) (
ASRs |
Cumulative
Maximum Hourly Average TSP Concentrations in mg/m3 |
||||
1.5m AGL |
5m AGL |
10m AGL |
15m AGL |
20m AGL |
|
CHA1 |
NA |
210 |
196 |
178 |
159 |
CHA2 |
NA |
214 |
166 |
155 |
145 |
EXA1 |
NA |
269 |
227 |
190 |
163 |
EXA2 |
NA |
357 |
240 |
195 |
164 |
EXA3 |
NA |
NA |
311 |
237 |
185 |
EXA4 |
NA |
365 |
NA |
NA |
NA |
EXA5 |
429 |
388 |
318 |
252 |
202 |
EXA6 |
533 |
NA |
NA |
NA |
NA |
EXA7 |
NA |
NA |
191 |
142 |
124 |
ADA1 |
203 |
207 |
194 |
179 |
164 |
ADA2 |
169 |
171 |
161 |
149 |
139 |
ADA3 |
NA |
154 |
150 |
145 |
139 |
ADA4 |
141 |
144 |
139 |
134 |
128 |
Notes: (1) The background TSP level of 73.0 mg/m3 is included in the above results.
(2) The hourly average TSP EIAO-TM criterion is 500 mg/m3.
(3) Boldfaced values represent the predicted TSP
concentration exceeds the respective criteria.
(4) The lowest sensitive level of EXA5 is 2m AGL.
Table 8.15 Predicted
Cumulative Maximum Daily Average TSP Concentrations at Representative Air
Sensitive Receivers (Tier 1 – Mitigated) (
ASRs |
Cumulative
Maximum Daily Average TSP Concentrations in mg/m3 |
||||
1.5m AGL |
5m AGL |
10m AGL |
15m AGL |
20m AGL |
|
CHA1 |
NA |
147 |
130 |
121 |
112 |
CHA2 |
NA |
146 |
122 |
113 |
107 |
EXA1 |
NA |
175 |
147 |
127 |
114 |
EXA2 |
NA |
211 |
149 |
129 |
114 |
EXA3 |
NA |
NA |
182 |
145 |
122 |
EXA4 |
NA |
223 |
NA |
NA |
NA |
EXA5 |
261 |
238 |
191 |
156 |
131 |
EXA6 |
275 |
NA |
NA |
NA |
NA |
EXA7 |
NA |
NA |
136 |
107 |
97 |
ADA1 |
141 |
142 |
135 |
126 |
118 |
ADA2 |
122 |
123 |
118 |
111 |
105 |
ADA3 |
NA |
115 |
113 |
110 |
106 |
ADA4 |
108 |
110 |
107 |
104 |
100 |
Note: (1) The background TSP
level of 73.0 mg/m3 is included in the
above results.
(2) The daily average TSP AQO criterion is 260 mg/m3.
(3) Boldfaced values represent the predicted TSP
concentration exceeds the respective criteria.
(4) The lowest sensitive level of EXA5 is 2m AGL.
8.94
Based on the results of the Tier 1 screening
test, the predicted TSP levels at the ASRs along Wanchai harbourfront between
8.95
The assessment results of Tier 2 test are summarized in Tables 8.16 – 8.17. The Tier 2 contour plots of cumulative
maximum hourly and daily average TSP concentrations at 1.5m AGL for scenarios 1 – 3 are presented in Figure Nos. NEX2213/C/331/ENS/M60/015 - NEX2213/C/331/ENS/M60/020.
Table 8.16 Predicted
Cumulative Maximum Hourly Average TSP Concentrations at Representative Air
Sensitive Receivers (Tier 2 – Mitigated) (
ASRs |
Cumulative Maximum Hourly Average TSP
Concentrations in mg/m3 |
||||
1.5m AGL |
5m AGL |
10m AGL |
15m AGL |
20m AGL |
|
EXA5 |
420 |
374 |
290 |
229 |
184 |
EXA6 |
341 |
NA |
NA |
NA |
NA |
Note: (1) The background TSP level of 73.0 mg/m3 is included in the above results.
(2) The
hourly average TSP EIAO-TM
criterion is 500 mg/m3.
(3) The
lowest sensitive level of EXA5 is 2m AGL.
Table 8.17 Predicted
Cumulative Maximum Daily Average TSP Concentrations at Representative Air
Sensitive Receivers (Tier 2 – Mitigated) (
ASRs |
Cumulative Maximum Daily Average TSP
Concentrations in mg/m3 |
||||
1.5m AGL |
5m AGL |
10m AGL |
15m AGL |
20m AGL |
|
EXA5 |
239 |
213 |
171 |
142 |
122 |
EXA6 |
206 |
NA |
NA |
NA |
NA |
Note: (1) The background TSP level of 73.0 mg/m3 is included in the above results.
(2) The
daily average TSP AQO
criterion is 260 mg/m3.
(3) The
lowest sensitive level of EXA5 is 2m AGL.
8.96
Based on the results of the Tier 2
assessment, the cumulative maximum hourly and daily average TSP at all ASRs located within the
hot spot area would comply with the criteria in EIAO-TM and AQO.
8.97
The cumulative maximum
annual average TSP concentrations amongst the three assessment scenarios at the
representative ASRs are predicted and presented in Table 8.18. The detailed
assessment results are presented in Appendix 8.8.
Table 8.18 Predicted
Cumulative Annual Average TSP Concentrations at Representative Air Sensitive
Receivers (Mitigated) (
ASRs |
Cumulative Annual Average TSP
Concentrations in mg/m3 |
||||
1.5m AGL |
5m AGL |
10m AGL |
15m AGL |
20m AGL |
|
CHA1 |
NA |
74.7 |
74.3 |
73.9 |
73.6 |
CHA2 |
NA |
74.5 |
74.1 |
73.8 |
73.6 |
EXA1 |
NA |
74.6 |
74.1 |
73.7 |
73.5 |
EXA2 |
NA |
76.7 |
74.8 |
74.1 |
73.7 |
EXA3 |
NA |
NA |
75.8 |
74.7 |
74.1 |
EXA4 |
NA |
77.0 |
NA |
NA |
NA |
EXA5 |
78.1 |
76.4 |
75.0 |
74.4 |
74.0 |
EXA6 |
77.4 |
NA |
NA |
NA |
NA |
EXA7 |
NA |
NA |
74.0 |
73.6 |
73.4 |
ADA1 |
74.7 |
74.6 |
74.3 |
74.0 |
73.7 |
ADA2 |
74.4 |
74.4 |
74.1 |
73.8 |
73.6 |
ADA3 |
NA |
73.8 |
73.7 |
73.6 |
73.5 |
ADA4 |
73.9 |
73.9 |
73.8 |
73.6 |
73.5 |
Note: (1) The background TSP level of 73.0 mg/m3 is included in the above results.
(2) The
annual average TSP AQO
criterion is 80 mg/m3.
(3) Boldfaced
values represent the predicted TSP concentration exceeds the respective
criteria.
(4) The
lowest sensitive level of EXA5 is 2m AGL.
8.98
Based on the
results shown in Table 8.18, the cumulative annual average TSP levels at all ASRs would comply with
the AQO after implementation of the proposed dust mitigation measures. The worst-hit level would be predicted
at 1.5m AGL and 5m AGL. The
contour plots of cumulative annual average TSP concentrations at 1.5m AGL and 5m AGL for scenarios 1 – 3
are presented in Figure Nos. NEX2213/C/331/ENS/M60/021
– NEX2213/C/331/ENS/M60/026. Marginal exceedances of annual average
TSP concentrations at 1.5m AGL are predicted at part of the buildings of
Renaissance Harbour View Hotel and Hong Kong Convention & Exhibition Centre
in the contour plots, the buildings of Renaissance Harbour View Hotel and Hong
Kong Convention & Exhibition Centre are provided with central air
conditioning and there are no fresh air intake at these areas, i.e. no air
sensitive areas within the exceedance areas. Some exceedances of annual average TSP concentrations at both 1.5m AGL
and 5m AGL are predicted at the vicinity of Wanchai Harbourfront area and
Causeway Bay Typhoon Shelter in the contour plots, however, there is no air
sensitive use at these areas and some are in most case transient and no adverse
impact is anticipated. The existing Harbour Road Sports Centre
and Wan Chai Swimming Pool would be demolished and in operation at south of its
original location, i.e. EXA7. The
new Harbour Road Sports Centre and Wan Chai Swimming Pool will be provided with
central air conditioning.
Exceedances of annual average TSP concentrations at 1.5m AGL are
predicted at the existing location of existing Harbour Road Sports Centre and
Wan Chai Swimming Pool in contour plot of scenario 3, however, the existing
Harbour Road Sports Centre and Wan Chai Swimming Pool will be demolished at
that time, and hence no air sensitive areas are located within the exceedance
areas.
8.99
The predicted mitigated maximum hourly and daily average TSP concentrations of Tier 1
screening test and annual average TSP concentration at the representative ASR during construction are summarized in Table
8.19.
8.100
Based on the results, the predicted mitigated
annual average TSP concentration at the representative ASR would comply with
the AQO. However, the predicted
mitigated maximum hourly average TSP concentration of the Tier 1 screening test would
exceed the EIAO-TM criteria. A
focused Tier 2 assessment was thus undertaken. The predicted mitigated maximum hourly and daily average TSP concentrations of the Tier
2 assessment at the representative ASR during construction are summarized in Table
8.19.
8.101
Based on the
results of Tier 2 testing, hourly and daily average TSP at the representative ASR would comply with the
criteria in EIAO-TM and AQO. As
there is only one ASR identified within the assessment boundary, contour of Tier
1 testing for screening purpose is not necessary. The contour plots of maximum hourly, daily (Tier 2 Assessment) and annual average TSP concentrations at 1.5m AGL are shown in Figure Nos. NEX2213/C/331/ENS/M60/027 –
NEX2213/C/331/ENS/M60/029.
Table 8.19 Predicted
Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative
Air Sensitive Receivers (Mitigated)
ASRs |
Maximum TSP Concentrations
in mg/m3 |
||||
Hourly Average |
Daily Average |
Annual Average |
|||
|
Tier 1 |
Tier 2 |
Tier 1 |
Tier 2 |
|
TWA1 (at 1.5m AGL) |
532 |
358 |
150 |
118 |
67.4 |
Note: (1) The background TSP level of 66.4 mg/m3 is included in the above results.
(2) The
hourly, daily and annual average TSP EIAO-TM/AQO criteria are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.
(3) Boldfaced value represents the
predicted TSP concentration exceeds the respective criteria.
Evaluation of Residual Impacts
8.102
With the implementation of the mitigation
measures as stipulated in the Air Pollution Control (Construction Dust)
Regulation together with the recommended dust control measures and good site
practices, no adverse residual impact would be expected on both
8.103
The operation of the concrete batching plant
is classified as a SP. The
Contractor should apply a SP license under APCO before operation. Suitable mitigation measures stipulated
in the Guidance Note on the Best Practicable Means for Cement Works (Concrete
Batching Plant) BPM 3/2(93) should be followed and implemented.
8.104
For the rest of the casting basin, with the
implementation of the mitigation measures as stipulated in the Air Pollution
Control (Construction Dust) Regulation together with the recommended dust
control measures and good site practices, the predicted dust impact at ASRs
would comply with the hourly, daily and annual TSP criteria in the EIAO-TM and
AQO.
Environmental Monitoring and
Audit Requirements
8.105
Environmental monitoring and audit for dust
emission should be conducted during the construction phase of the Project so as
to check compliance with legislative requirements. Details of the monitoring and audit
programme are contained in a stand-alone EM&A Manual.
8.106 Potential air quality impacts from the construction works of the Project would mainly be related to construction dust from excavation, materials handling, spoil removal and wind erosion. With the implementation of mitigation measures specified in the Air Pollution Control (Construction Dust) Regulation together with the recommended dust suppression measures, good site practices, and EM&A programme, the predicted dust impact at ASRs would comply with the hourly, daily and annual TSP criteria in the EIAO-TM and AQO. No adverse residual impact is anticipated.
[1] Territory Development
Department (July 2001). Central
Reclamation, Phase III Studies, Site Investigation, Design and Construction,
Environmental Monitoring and Audit Manual
[2] Maunsell Consultants
Asia Ltd, Environmental Impact Assessment Report (
[3] USEPA Compilation of Air Pollutant Emission Factors (AP-42), Appendix B.2, Page B.2-13
[4] USEPA, AP-42, “Control of Open Fugitive Dust Sources”.
[5] USEPA AP-42, “Control Techniques for Particulate Emission for Stationary Sources Volume 2”. It states that watering alone would reduce the dust emission by 50%. However, the unloading facilities is enclosed by a 3-side screen with top, addition dust removal efficiency is expected. Thus, it is a very conservative assumption.