3.1
This Section presents an assessment of the
potential air quality impacts associated with the construction and operation
phases of the Project. Representative Air
Sensitive Receivers (ASRs) have been identified and the potential air quality
impacts on these receivers arising from construction dust emission and vehicle
emission have been evaluated.
Appropriate mitigation measures have been proposed to alleviate the
potential air quality impacts, if necessary.
Environmental Legislation, Standards and Guidelines
Air Quality
Objective & EIAO-TMs
3.2
The criteria for evaluating air
quality impacts and the guidelines for air quality assessment are laid out in
Annex 4 and Annex 12 of the Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM),
respectively.
3.3
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 must be satisfied, stipulate the maximum
allowable concentrations over specific period for typical pollutants. The relevant AQOs are listed in Table
3.1.
Table 3.1
|
|
Maximum
Concentration (µg m-3) (1) |
|||
|
Pollutant |
Averaging
Time |
|||
|
|
1
hour (2) |
8
hour (3) |
24
hour (3) |
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 |
- |
- |
- |
Note:
(1)
Measured at 298 K and 101.325 kPa.
(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.
3.4
The EIAO-TM stipulates that the hourly TSP level should not exceed
Air
Pollution Control (Construction Dust) Regulation
3.1
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. Contractors and site agents are required to
inform EPD on carrying out construction works and to adopt dust reduction
measures to reduce dust emission to the acceptable level.
Practice
Note on Control of Air Pollution in Vehicle Tunnels
3.2
The Practice Note on Control of Air Pollution in
Vehicle Tunnels, prepared by the Environmental Protection Department (EPD),
provides guidelines on control of air pollution in vehicle tunnels. Guideline values on tunnel air quality are
presented in Table 3.2.
Table 3.2 Tunnel Air Quality Guidelines (TAQG)
|
Air
Pollutant |
Averaging
Time |
Maximum
Concentration |
|
|
(mg/m3)
(1) |
ppm |
||
|
Carbon
Monoxide (CO) |
5
minutes |
115,
000 |
100 |
|
Nitrogen
Dioxide (NO2) |
5
minutes |
1,800 |
1 |
|
|
5
minutes |
1,000 |
0.4 |
Note: (1)
Expressed at reference conditions of 298K and 101.325kPa.
3.3
The Project site is located in the North Wan Chai
District, and is located between
3.4
The EPD air quality monitoring station at Central/Western
is located nearest to the study area of the Project. The annual average concentrations of
pollutants as indicated in
Table 3.3 EPD Air Quality Monitoring Data at Central/Western Station in 2003
|
Pollutant |
Annual
Average Concentration (μg/m3) |
|
Central/Western |
|
|
SO2 |
18 |
|
NO2 |
52 |
|
Ozone |
44 |
|
TSP |
75 |
|
RSP |
53 |
3.5
In
accordance with Annex 12 of the EIAO-TM, representative existing
and planned worst affected air sensitive receivers (ASRs) in the proximity of
the Project
were selected. The fresh air
intakes of HKCEC Phase II are located at the roof of its building. In view of the high elevation of the
locations, no adverse traffic emission impact would be expected on these fresh
air intakes, therefore, the fresh air intakes of HKCEC Phase II have not been
considered in the assessment. Planned
receivers were identified from the Draft Wan Chai North Outline Zoning Plan No.
S/H25/1. Table 3.4 summarises
the selected ASRs for the air quality impact assessment. The locations of representative ASRs in the
vicinity of the proposed work areas are illustrated in Figure 3.1.
Table 3.4 Representative Air Sensitive Receivers
|
ASR |
Description |
Land Use |
Distance (m) |
Assessment Height (m above ground) |
|
A1 |
North Island Line Ventilation Shafts (planned fresh
air intake) |
Other Use |
320 |
3.5* |
|
A2 |
Harbour Centre |
Commercial |
205 |
1.5 (G/F) 8 (podium
level) 28 (8/F
A)* 58 (18/F
A)* 85 (27/F
A)* 103 (33/F
A)* |
|
A3 |
Great Eagle Centre |
Commercial |
135 |
1.5 (G/F) 8 (podium
level) 28 (8/F
A)* 58 (18/F
A)* 85 (27/F
A)* 103 (33/F
A)* |
|
A4 |
New World Renaissance Harbour View Hotel |
Commercial |
within
construction area |
5 (1/F)* 10.3
(M/F)* 14.5
(2/F)* 18.5
(3/F)* 22.5
(4/F)* 32 (6/F)* 44.3
(8/F)* |
|
A5 |
|
Commercial |
within construction
area |
3* |
|
A6 |
Grand Hyatt Hotel |
Commercial |
within
construction area |
5* |
|
A7 |
|
Commercial |
34 |
14.5
(2/F)* 22.5
(4/F)* 26.9
(5/F)* 32 (6/F)* 38.8
(7/F)* 44.3
(8/F)* |
|
A8 |
|
Open Area |
106 |
3.5 |
|
A9 |
Waterfront Related Commercial and Leisure Uses |
Commercial |
200 |
1.5 |
|
A10 |
Planned CDA |
Residential/ Commercial |
138 |
1.5, 5, 10 |
|
A11 |
Planned CDA |
Residential/ Commercial |
100 |
1.5, 5, 10 |
|
A12 |
OU(Railway Air Intake Location) zone |
Other Use |
28 |
3.5* |
|
A13 |
Existing Children Playground |
Other Use |
220(Long-term
scenario) 162(Interim
Scenario) |
1.5 |
Note: * Fresh
air intake location
3.6
As noted from site visits, the identified ASRs A2, A3, A4, A5,
A6 and A7 are provided with central ventilation systems. As such, the heights
of assessment points of these ASRs are the fresh air intake locations. For ASRs A2 and A3, 1.5 meter above ground level
and the podium level were also considered in the assessment.
Construction Phase
3.7
The major construction activities of the Project would
be temporary foundation work (footbridge/working platform), demolition of existing
atrium link, and building construction works for the new Atrium Link
Extension. The construction work would
commence in May 2006 and would be completed by March 2009. Gaseous emission from construction plant
would be limited as only a few construction plants would be operated in limited
works area. In view of the scale of the
Project and nature of the major construction activities, minor dust impacts
would be expected.
Operation Phase
3.8
Vehicle exhaust emissions, in particular NO2 and RSP,
from existing roads and planned roads under WDII Project (if WDII Project goes
ahead) would be the major pollutant sources during the operation phase. As the WDII Project has not been confirmed,
two assessment scenarios, Long-term Scenario (with implementation of WDII
Project & CWB Project) and Interim Scenario (without implementation of WDII
Project & CWB Project), have been considered in the EIA Study. The traffic emission sources within
Long-Term Scenario (With the
implementation of WDII Project and CWB Project)
Ÿ
vehicle emissions from open sections of existing and planned
road networks (including Road P2 and CWB) in WDII Project
Ÿ
tunnel portal emission from CWB westbound slip road
Ÿ
emission from
Ÿ
portal emissions from the planned deckovers along Road P2
Ÿ
portal emission from deckover on
Ÿ
portal emission from proposed deckover (New Atrium Link
Extension) between Expo Drive Central and
Interim Term Scenario (Without the
implementation of WDII Project and CWB Project)
Ÿ
vehicle emissions from road networks without WDII Project
and CWB Project
Ÿ
portal emission from deckover on
Ÿ
portal emission from proposed deckover (New Atrium Link
Extension) between Expo Drive Central and
3.9
The proposed deckover would be about 120 -
Construction Phase
3.10
As mentioned in Section 3.11, insignificant dust
impact would be expected during construction phase of the Project, therefore,
only qualitative assessment would be undertaken in the EIA study.
Operational Phase
3.11
As mentioned in Section 3.12, two assessment scenarios
were considered in the EIA study and the detailed methodology for each scenario
is discussed as follows.
Long-term Scenario (With the
implementation of WDII Project and CWB Project)
3.12
Potential air quality impact during the operational
phase of the WDII project and CWB Project includes the following pollutant
sources. The locations of the sources
are indicated in Figure 3.2 and the
cross section diagram showing spatial distri
Ÿ
background pollutant levels based on five years averaged
monitoring data from EPD monitoring stations at Central/Western
Ÿ
vehicle emissions from open sections of existing and planned
road networks in WDII Project and CWB Project
Ÿ
tunnel portal emission from CWB westbound slip road
Ÿ
emissions from
Ÿ
portal emissions from the planned deckovers along Road P2
Ÿ
portal emission from deckover over
Ÿ
portal emission from proposed deckover (New Atrium Link)
between Expo Drive Central and
Background Concentrations
3.14
Carbon Monoxide (CO) was not measured at
Central/Western Stations. The annual average CO concentrations were available
at Tsuen Wan Station, Tung Chung Station and Tap Mun Station. As the annual average CO concentration measured
at Tsuen Wan was greater that the others, the 5-year averaged (1998-2002)
annual concentration of CO measured at Tsuen Wan air quality monitoring station
has been adopted as the background air quality of CO. Table 3.5 summarises the annual
average concentrations of the pollutants considered as background
concentrations for the cumulative impact assessment.
Table 3.5 Annual Average Concentrations of Pollutants in Past Five Years
|
Pollutant |
Annual Average Concentration in
Past Five Years (1997-2000, 2003) at Central/Western Station (mg
m-3) |
|
NO2 |
54 |
|
RSP |
52 |
|
SO2 |
17 |
|
Pollutant |
Annual Average Concentration in
Past Five Years (1998-2002) at Tsuen Wan Station (mg
m-3) |
|
CO |
929 |
Vehicle Emissions from Open
Sections of Existing and Planned Road Networks in WDII Project & CWB
Project
3.15
The CALINE4 dispersion model was used for calculation
of the 1-hour NO2, 24-hour NO2, and 24-hour RSP
concentrations. Open sections of
existing and planned road networks within
Ÿ
new roads in the WDII Project
Ÿ
new roads in the Central Reclamation Phase III (CRIII)
Ÿ
the CWB and associated roads
Ÿ
the existing roads (including Harbour Road, Fleming Road,
Convention Avenue, Gloucester Road, Harcourt Road, and Hennessy Road)
3.16
The predicted morning peak hour traffic flows and
vehicle mixes for the road networks in Year 2027 were used for the assessment
as the worst-case air quality scenario. Figures
3.3 shows the projected Year 2027 morning peak hour traffic flows and
vehicle compositions. The confirmation
letter from Transportation Department is attached in Appendix 3.3.
3.18
The composite emission factors for the road links were
calculated as the weighted average of the emission factors of different types
of vehicles. Four vehicle categories
have been adopted. As a worst-case
scenario, maximum emission factor within each category was used for the
assessment. The emission factors for
different vehicle categories are listed in Table 3.6. Detailed calculations of the emission factors
are shown in Appendix 3.3.
Table 3.6 Emission Factors for Year 2011 for Different Vehicle Categories (EURO4)
|
Pollutant |
Emission Factors for 2011 (EURO4),
g/km-veh |
|||
|
PV (1) |
LGV (2) |
HGV (3) |
PT (4) |
|
|
NOx |
0.54 |
0.97 |
3.46 |
6.15 |
|
RSP |
0.03 |
0.09 |
0.36 |
0.45 |
Note: (1) Private
Vehicles (PV) include taxi and private car.
(2)
Light Goods
Vehicles (LGV) include passenger van and light goods vehicle.
(3)
HGV stands for
Heavy Goods Vehicles.
(4)
Public
Transport (PT) includes all types of buses.
3.20
In order to calculate the cumulative pollutant
concentrations from different sources using different models (CALINE4 and
ISCST3) in the later part of the assessment, the dispersion modelling was
undertaken assuming 360 predetermined meteorological conditions and the highest
predicted pollutant concentration amongst the 360 wind directions was
identified. The following summarises the
meteorological conditions adopted in the air quality modelling using the
CALINE4 model:
Ÿ
Wind speed :
Ÿ
Wind direction : 360 wind directions
Ÿ
Resolution : 1°
Ÿ
Wind variability : 24°
Ÿ
Stability class : D
Ÿ
Surface roughness :
Ÿ
Mixing height :
3.21
The CALINE4 model calculates hourly concentrations
only. With reference to the Screening Procedures for Estimating the Air
Quality Impact of Stationary Source (EPA-454/R-92-019), a conversion factor
of 0.4 was used to convert the 1-hour average concentrations to 24-hour average
concentrations.
3.22
Referring to the WDII EIA Report, there are no
proposed barriers/enclosures identified within
Emissions from Ventilation
Buildings
3.23
The Industrial Source Complex Short Term (ISCST3)
dispersion model was used to predict the emission from ventilation
buildings. The emissions from Central
Ventilation Building of CWB for extracting vitiated tunnel air from Slip Road F
and CWB Westbound was considered in the assessment. The ventilation building emissions in accordance with WDII EIA Report
are summarised in Table 3.7.
Table 3.7 Ventilation Buildings Emissions from CWB
|
Type |
Emission
Rate (g s-1) |
|
|
NO2
* |
RSP |
|
|
Slip Road
F |
0.12222(1) |
0.01092(1) |
|
Central-Wanchai
Bypass Westbound |
0.04884(1) |
0.00867(1) |
Note: *
Based on 20% NO2/NOx conversion in ambient condition.
(1) Adopted
from Environmental Impact Assessment of Wan Chai Development Phase II
Comprehensive Feasibility Study
3.24
The preliminary design of the ventilation buildings
(including minimum discharge heights, exhaust directions, handling capacity of
ventilation buildings and exit velocity) in accordance with the WDII EIA Report
is summarised in Table 3.8. For a
worst case scenario in the air quality assessment, the minimum height of stack
was used in modelling.
Table 3.8 Design of Central Ventilation Buildings
|
|
Maximum capacity (m3 s-1) |
Exit velocity (m s-1) |
Minimum discharge height (m
above ground) |
Exhaust direction |
|
Slip Road F |
180 |
8 |
15 |
vertical |
|
Central Wanchai Bypass Westbound |
100 |
8 |
15 |
vertical |
3.25
As mentioned in Section 3.23, 360 predetermined
meteorological conditions were used. The
following summarises the meteorological conditions adopted in the air quality
modelling using the ISCST3 model:
Ÿ
Wind speed :
Ÿ
Wind direction : 360 wind directions
Ÿ
Resolution : 1°
Ÿ
Stability class : D
Ÿ
Mixing height :
Ÿ
Emission temperature : 25°
Portal Emissions
3.26
The Industrial Source Complex Short Term (ISCST3)
dispersion model was used to predict the portal emissions. The locations of the
portal emissions considered in the assessment are indicated in Figure 3.2. The portal emissions considered in the model
include:
Ÿ
tunnel portal emission from CWB westbound
Ÿ
portal emissions from the planned deckovers along Road P2
Ÿ
portal emission from deckover over
Ÿ
portal emission from proposed deckover (New Atrium Link)
between Expo Drive Central and
3.27
The portal emissions (NO2 and RSP) were
calculated based on the vehicle emission (EURO4) and vehicle flows in Year
2027. Appendix 3.4 shows the calculations of portal emissions.
3.28
Portal emissions were modelled in accordance with the Permanent International Association of Road
Congress Report (PIARC, 1991).
Pollutants were assumed to eject from the portal as a portal jet such that
2/3 of the total emissions was dispersed within the first
3.29
As mentioned in Section 3.23, 360 predetermined
meteorological conditions were used. The
meteorological conditions adopted in the air quality modelling using the ISCST3
model are those described in Section 3.28.
3.30
The
width of the proposed deckover (New Atrium Link) would be approximately
Table 3.9 Portals Emissions from Proposed Deckover (Long-term Scenario)
|
Type |
Emission
Rate (g s-1) |
|
|
NO2
* |
RSP |
|
|
Portal Emission |
||
|
|
0.0148 |
0.0056 |
|
|
0.0013 |
0.0004 |
|
|
0.0043 |
0.0015 |
|
|
0.0085 |
0.0030 |
|
Central
Wan Chai Bypass Eastbound |
0.0126 |
0.0049 |
|
Central Wan
Chai Bypass Westbound(1) |
0.0778 |
0.0293 |
|
Convention
Avenue |
0.0046 |
0.0016 |
Note:
* Based on 20% NO2/NOx conversion in ambient condition.
(1) Portal Emission Rate includes Tunnel
Emission and open road emission of Central Wan Chai Bypass Westbound under the
Proposed Deckover.
Cumulative Impact
3.31
To obtain the cumulative pollutant concentration at
each receptor, two sets of 360 values each were first derived from the CALINE4 and
the ISCST3 models respectively, for the 360 wind directions. The corresponding components of these two
sets of 360 values were then added together and the highest value among the 360
wind directions was identified and considered as the highest predicted
pollutant concentration level at the receptor.
3.32
Background pollutant concentrations were added to the
results calculated above to produce the worst-case concentrations.
Vehicular Emission under the
Proposed Atrium Link Deck
3.33
Under
the proposed deckover (New Atrium Link), all roads considered in the assessment
for the Long-term Scenario including (i) Expo Drive Central, (ii) CWB
eastbound, (iii) Road P2 eastbound, (iv) Road P2 westbound, (v) CWB westbound
including tunnel section and (vi) Convention Avenue.
3.34
As
mentioned in Section 3.33, under the proposed deckover,
(i)
Deckover along Expo Drive Central – emissions contri
(ii)
Deckover along Road P2 Eastbound & Westbound and CWB
Eastbound & Westbound – emissions contri
(iii)
Deckover along
3.35
As
the representative ASRs are located along the
3.36
The vehicular emissions (NO2, CO & SO2)
under the proposed deck were calculated in the assessment. A conversion factor of 12.5%
including tailpipe NO2 emission (taken as 7.5% of NOx) plus 5% of NO2/NOx for tunnel
air recommended in PIARC for air expelled from the tunnel was taken in this
assessment as the inside tunnel conversion factor. Two scenarios were considered: i.e. normal
traffic flow condition and congested traffic flow condition. Vehicle speed of 50 kph was assumed in the
assessment for normal traffic flow condition.
For the congested mode, the separation between vehicles was assumed to
be
Interim Scenario (Without WD II Project
& CWB Project)
3.37
Potential air quality impact during the operation phase of Interim scenario
includes the following pollutant sources.
The location of these emission sources are indicated in Figure 3.4 and the cross section
diagram showing spatial distri
Ÿ
background pollutant levels based on five years averaged
monitoring data from EPD monitoring station at Central/Western
Ÿ
vehicle emissions from open sections of existing road
networks
Ÿ
portal emission from deck over
Ÿ
portal emission from proposed deckover between Expo Drive
Central and the
Background Concentrations
3.38
The annual average concentrations of the pollutants measured
at EPD’s Central / Western and Tsuen Wan air quality monitoring stations was
considered in the assessment. For
details refer to Section 3.17.
Vehicle Emissions from Open Sections of Existing Road Networks
3.39
The
CALINE4 dispersion model was used for calculation of the 1-hour NO2, 24-hour NO2, and 24-hour RSP
concentrations. Open sections of
existing road networks within
3.40
The proposed Atrium Link Extension would be completed
in Year 2009 and the maximum traffic flow would be expected in Year 2024 within 15 years of the
operation. A sensitivity
test for emission rates of Year 2009 and 2024 was conducted and the calculation
is presented in Appendix 3.1. Results indicated that the traffic emission
rates in Year 2024 are higher and therefore the predicted morning peak hour
traffic flows and vehicle mixes for the road networks in Year 2024 were used
for the assessment of the worst-case air quality scenario. Figure
3.5 shows the projected Year 2024 morning peak hour traffic flows and
vehicle compositions. The confirmation letter from Transportation Department is
attached in Appendix 3.5.
3.41
The most up-to-date vehicular emission factors (Fleet
Average Emission Factors – EURO4 Model) available from the EPD are for the year
2011 and these were adopted for the assessment.
It is, however, believed that the 2024 emission rates would be lower
than those of 2011, as more stringent vehicle emission control will have been
in place by that time. The predicted
results are therefore conservative.
3.42
The vehicular emissions for different vehicle categories
are listed in Table 3.6. Detailed
calculations of the emission factors are shown in Appendix 3.5. The
meteorological conditions adopted in the air quality modelling using the
CALINE4 model were the same as the long-term scenario.
Portal Emissions
3.43
The Industrial Source Complex Short Term (ISCST3)
dispersion model was used to predict the portal emissions. The locations of the
portal emissions from proposed ALE deck are indicated in Figure 3.4.
3.44
The method for calculation of portal emissions was
similar to the Long-term Scenario. As
the separation distance between Expo Drive Central and
Table 3.10 Portals Emissions from Proposed Deckover (Interim Scenario)
|
Type |
Emission Rate (g s-1) |
|
|
NO2 * |
RSP |
|
|
Portal
Emission |
||
|
|
0.0024 |
0.0007 |
|
|
0.0025 |
0.0007 |
|
Convention Avenue |
0.0101 |
0.0033 |
Note: * Based
on 20% NO2/NOx conversion in ambient condition.
Cumulative Impact
3.45
The
cumulative pollutant concentrations at the ASRs were calculated using the same methodology
as the Long-term Scenario (refer to Sections 3.34 & 3.35).
Vehicular Emission under the Proposed Atrium Link Deck
3.46
Underneath
the
Identification, Prediction and Evaluation of Air Quality Impacts
Construction Phase
3.47
Due to limited construction work for the Project and less
dusty construction activities, significant dust impact and emissions from
operated construction equipment would not be expected.
Operation Phase
Long-term Scenario (With the
implementation of WDII Project and CWB Project)
Air Quality from Open Roads
3.48
Taking into account vehicle emissions from open road
networks, portal and ventilation building emissions from the CWB, portal emission from the planned
deckover and the background pollutant concentration, the cumulative 1-hour NO2,
24-hour NO2 and 24-hour RSP concentrations at each ASR were
calculated. The predicted concentrations
of ASRs are listed in Table 3.11.
Table 3.11 Predicted Cumulative 1-hour Average NO2, 24-hour Average NO2 and 24-hour Averaged RSP at the Representative ASRs (Long-term Scenario)
|
ASR |
Assessment Height (mAG) |
Predicted Concentration (mg/m-3) |
||
|
1-hour Averaged NO2 |
24 hr Averaged NO2 |
24 hr Averaged RSP |
||
|
A1 |
3.5 |
92 |
69 |
57 |
|
A2 |
1.5 |
100 |
73 |
58 |
|
8 |
97 |
71 |
58 |
|
|
28 |
79 |
64 |
55 |
|
|
58 |
66 |
59 |
54 |
|
|
85 |
61 |
57 |
53 |
|
|
103 |
60 |
56 |
52 |
|
|
A3 |
1.5 |
109 |
76 |
59 |
|
8 |
99 |
72 |
58 |
|
|
28 |
78 |
63 |
55 |
|
|
58 |
66 |
59 |
53 |
|
|
85 |
61 |
57 |
53 |
|
|
103 |
59 |
56 |
52 |
|
|
A4 |
5 |
988* |
- |
- |
|
10.3 |
103 |
73 |
59 |
|
|
14.5 |
99 |
72 |
58 |
|
|
18.5 |
95 |
70 |
58 |
|
|
22.5 |
90 |
69 |
57 |
|
|
32 |
80 |
64 |
56 |
|
|
44.3 |
69 |
60 |
54 |
|
|
A5 |
3 |
988* |
- |
- |
|
A6 |
5 |
988* |
- |
- |
|
A7 |
14.5 |
101 |
73 |
59 |
|
22.5 |
79 |
64 |
55 |
|
|
26.9 |
77 |
63 |
55 |
|
|
32 |
74 |
62 |
55 |
|
|
38.8 |
70 |
60 |
54 |
|
|
44.3 |
67 |
59 |
54 |
|
|
A8 |
3.5 |
125 |
83 |
62 |
|
A9 |
1.5 |
136 |
87 |
63 |
|
A10 |
1.5 |
132 |
85 |
62 |
|
5 |
118 |
79 |
61 |
|
|
10 |
98 |
72 |
58 |
|
|
A11 |
1.5 |
124 |
82 |
61 |
|
5 |
110 |
76 |
59 |
|
|
10 |
92 |
69 |
57 |
|
|
A12 |
3.5 |
107 |
75 |
60 |
|
A13 |
1.5 |
111 |
77 |
60 |
Note: * ASRs A4, A5 & A6
are located within proposed deckover, the results of in-tunnel air quality are
presented.
3.49
The
above results indicated that the average NO2 and RSP concentrations at all the representative
ASRs except ASRs A4, A5 and A6 would comply with the AQO limits. Other than ASRs A4, A5 and A6, the
concentrations of 1-hour average NO2, 24-hour average NO2 and 24 hour average RSP of other
representative ASRs were predicted to range from 59 to
Air Quality under the Proposed Atrium Link Deck
3.50
The
assessment results of NO2 concentrations, CO and SO2
concentrations underneath the proposed Atrium Link Extension are summarised in Tables
Table
|
|
NO2
(mg/m3) |
||
|
Deckover Section |
Criteria/Standard
(1) |
Normal Traffic |
Congested Traffic |
|
|
1,800 |
147 |
144 |
|
Road
P2 and CWB (2) |
1,800 |
337 |
365 |
|
Convention
Avenue (2) |
1,800 |
595 |
988 |
Note: (1) The in-tunnel Air Quality
Criteria over 5 minutes average
(2) including tunnel
portal emission from CWB westbound
Table 3.12b In-Tunnel Air Quality Results (Long-term Scenario) – Carbon Monoxide (CO)
|
|
CO (mg/m3) |
||
|
Deckover Section |
Criteria/Standard
(1) |
Normal Traffic |
Congested Traffic |
|
|
115,000 |
2,166 |
2,117 |
|
Road
P2 and CWB (2) |
115,000 |
4,501 |
5,051 |
|
Convention
Avenue (2) |
115,000 |
10,768 |
18,607 |
Note: (1) The in-tunnel Air Quality
Criteria over 5 minutes average
(2) including tunnel
portal emission from CWB westbound
Table
|
|
SO2
(mg/m3) |
||
|
Deckover Section |
Criteria/Standard
(1) |
Normal Traffic |
Congested Traffic |
|
|
1,000 |
27 |
27 |
|
Road
P2 and CWB (2) |
1,000 |
47 |
52 |
|
Convention
Avenue (2) |
1,000 |
101 |
168 |
Note: (1) The in-tunnel Air Quality Criteria
over 5 minutes average
(2) including tunnel
portal emission from CWB westbound
3.51
According
to the results, the predicted NO2, CO and SO2
concentrations at the three ‘tunnel tubes” would comply with the respective
In-Tunnel Air Quality Guidelines.
3.52
However,
the air quality of ASRs A4, A5 and A6 and the area underneath the Atrium Link
Extension would not comply with the AQO, mitigation measures would be
required.
3.53
In
view of the proposed deckover, the background air quality outside the planned CWB
eastbound tunnel would be different comparing with the condition predicted in
the WDII EIA Study. However, the impact to the CWB tunnel air quality would be
alleviated as the design of
Interim Scenario (Without the
implementation of WDII Project and CWB Project)
Air Quality from Open Roads
3.54
Taking into account vehicle emissions from open road networks, portal
emissions from the proposed deckover, and the background pollutant
concentration, the cumulative 1-hour NO2, 24-hour NO2 and
24-hour RSP concentrations at each ASR were calculated. The predicted concentrations are listed in Table 3.13.
|
ASR |
Assessment Height (mAG) |
Predicted Concentration (mg/m-3) |
||
|
1-hour Averaged NO2 |
24 hr Averaged NO2 |
24 hr Averaged RSP |
||
|
A1 |
3.5 |
98 |
72 |
58 |
|
A2 |
1.5 |
101 |
73 |
58 |
|
8 |
96 |
71 |
57 |
|
|
28 |
75 |
63 |
55 |
|
|
58 |
62 |
57 |
53 |
|
|
85 |
57 |
55 |
52 |
|
|
103 |
56 |
55 |
52 |
|
|
A3 |
1.5 |
111 |
77 |
59 |
|
8 |
101 |
73 |
58 |
|
|
28 |
71 |
61 |
54 |
|
|
58 |
61 |
57 |
53 |
|
|
85 |
57 |
55 |
52 |
|
|
103 |
56 |
55 |
52 |
|
|
A4 |
5 |
183* |
- |
- |
|
10.3 |
90 |
69 |
57 |
|
|
14.5 |
86 |
67 |
56 |
|
|
18.5 |
82 |
65 |
56 |
|
|
22.5 |
78 |
64 |
55 |
|
|
32 |
70 |
60 |
54 |
|
|
44.3 |
64 |
58 |
53 |
|
|
A5 |
3 |
183* |
- |
- |
|
A6 |
5 |
183* |
- |
- |
|
A7 |
14.5 |
80 |
65 |
55 |
|
22.5 |
77 |
63 |
55 |
|
|
26.9 |
75 |
62 |
55 |
|
|
32 |
73 |
61 |
54 |
|
|
38.8 |
70 |
60 |
54 |
|
|
44.3 |
67 |
59 |
54 |
|
|
A8 |
3.5 |
82 |
65 |
55 |
|
A9 |
1.5 |
81 |
65 |
55 |
|
A10 |
1.5 |
102 |
73 |
58 |
|
5 |
100 |
72 |
58 |
|
|
10 |
94 |
70 |
57 |
|
|
A11 |
1.5 |
138 |
88 |
63 |
|
5 |
120 |
80 |
60 |
|
|
10 |
99 |
72 |
58 |
|
|
A12 |
3.5 |
122 |
81 |
61 |
|
A13 |
1.5 |
104 |
74 |
58 |
Note: * ASRs A4, A5
& A6 are located within proposed deckover, the results of in-tunnel air
quality are presented.
3.55
The
above results indicate that the average NO2 and RSP concentrations at all representative
ASRs would comply with the AQO limits.
The concentrations of 1-hour average NO2, 24-hour average NO2 and 24 hour average RSP were
predicted to range from 56 to
Air Quality under the Proposed Atrium Link Deck
3.56
For
the air quality underneath the proposed deck, the predicted NO2, CO and
SO2 concentrations
of normal and worst condition are summarized in Tables
Table
|
|
NO2
(mg/m3) |
||
|
Deckover Section |
Criteria/Standard
(1) |
Normal Traffic |
Congested Traffic |
|
|
1800 |
121 |
130 |
|
Convention
Avenue (2) |
1800 |
146 |
183 |
Note: (1) The in-tunnel Air
Quality Criteria over 5 minutes.
(2) including
tunnel portal emission from CWB westbound
Table 3.14b In-Tunnel Air Quality Results (Interim Scenario) – Carbon Monoxide (CO)
|
|
CO (mg/m3) |
||
|
Deckover Section |
Criteria/Standard
(1) |
Normal Traffic |
Congested Traffic |
|
|
115,000 |
2,049 |
2,279 |
|
Convention
Avenue (2) |
115,000 |
2,332 |
3,229 |
Note: (1) The in-tunnel Air Quality
Criteria over 5 minutes average
(2) including tunnel
portal emission from CWB westbound
Table
|
|
SO2
(mg/m3) |
||
|
Deckover Section |
Criteria/Standard
(1) |
Normal Traffic |
Congested Traffic |
|
|
1,000 |
27 |
29 |
|
Convention
Avenue (2) |
1,000 |
30 |
38 |
Note: (1) The in-tunnel Air Quality
Criteria over 5 minutes average
(2) including tunnel
portal emission from CWB westbound
3.57
The predicted air quality underneath the Atrium Link
Extension would comply with both the AQO and In-Tunnel Air Quality
Guideline. The open spaces under the
proposed deckover can continue to be used by the public in the Interim
Scenario.
Construction Phase
3.58
To ensure compliance with the relevant standards, dust mitigation
measures stipulated in the Air Pollution Control (Construction Dust) Regulation
and good site practices should be incorporated in the contract document to
control potential dust emission from the site.
The major dust suppression measures include:
Ÿ
skip hoist for material transport should be totally enclosed
by impervious sheeting
Ÿ
every vehicle should be washed to remove any dusty materials
from its body and wheels before leaving a construction site
Ÿ
the area where vehicle washing takes place and the section
of the road between the washing facilities and the exit point should be paved
with concrete, bituminous materials or hardcores
Ÿ
where a site boundary adjoins a road, streets or other
accessible to the public, hoarding of not less than
Ÿ
every stock of more than 20 bags of cement should be covered
entirely by impervious sheeting placed in an area sheltered on the top and the
3 sides
Ÿ
all dusty materials should be sprayed with water prior to
any loading, unloading or transfer operation so as to maintain the dusty
materials wet
Ÿ
the height from which excavated materials are dropped should
be controlled to a minimum practical height to limit fugitive dust generation
from unloading
Ÿ
The load of dusty materials carried by vehicle leaving a construction
site should be covered entirely by clean impervious sheeting to ensure dust
materials do not leak from the vehicle
Ÿ
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
Operation Phase
3.59
Referring
to Table 3.11, except exceedance of AQO found at ASRs A4, A5 and A6, the predicted air quality impacts
at the representative ASRs would comply with the AQO in the Long-term Scenario. It is recommended to divert these affected
fresh air intakes to the new air vent shaft provided for the Atrium Link
Extension. The location of the proposed
fresh air intake (+55.8 mPD) is indicated in Figure 3.6. The predicted
concentrations of 1-hour average NO2, 24-hour average NO2 and 24-hour average RSP at proposed
fresh air intake would be
3.60
Referring
to Table 3.13, the predicted air quality impacts at all representative ASRs would
comply with the AQO in the Interim Scenario.
The existing vent shaft for Renaissance Harbour View Hotel (ASR A4 at
the levels higher than the proposed deckover) would be blocked by the new
Atrium Link Extension. In view of
provision of good indoor air quality to these sensitive receivers , it is also
recommended that these fresh air intakes, (Hong Kong Convention and Exhibition
Centre Phase I, Renaissance Harbour View Hotel and Grand Hyatt Hotel), be
diverted to the new air vent shaft provided for the Atrium Link Extension
(where the intake location is at +55.8 mPD).
The predicted concentrations of 1-hour average NO2, 24-hour average NO2 and 24-hour average RSP at proposed
new fresh air intake would be
3.61
The
HKCEC and the Hotel management have agreed on the diversion of fresh air
intakes (see Appendix 3.9).
3.62
Based
on the assessment methodology and assumptions (e.g. no good mixing of air
pollutants under the proposed deck and no ventilation system provided), the air
quality underneath the Atrium Link Extension is predicted to comply with both
the AQO and In-Tunnel Air Quality Guidelines in the Interim Scenario. In the
Long-term scenario, the
air quality underneath the Atrium Link Extension would comply with the EPD
Tunnel Air Quality Guidelines but would not comply with the AQO. According to the current Draft Wan Chai North
Outline Zoning Plan, the planned land use underneath the Atrium Link Extension
is “Road”. However, in view of exceedance of AQO, the area underneath the
Atrium Link Extension would not be suitable for placing any air sensitive
receivers in the Long-term scenario.
Construction Phase
3.63
With
the implementation of recommended
mitigation measures during construction of the Atrium Link Extension, no
adverse residual air quality impact would be expected.
Operation Phase
3.64
No adverse residual air quality impact on the
representative ASRs would be identified during operational phase of the Project
with the re-diversion of the fresh air intakes of ASRs A4, A5 and A6 for
Long-term Scenario and Interim Scenario.
3.65
According to the current Draft
Wan Chai North Outline Zoning Plan, the planned land use underneath the Atrium
Link Extension is “Road” which is not ASR. In view of exceedance of AQO,
however, the area underneath the Atrium Link Extension would not be suitable
for placing any air sensitive receivers in the Long-term Scenario.
Environmental Monitoring and Audit
Construction Phase
3.66
With the implementation of the proposed dust suppression measures (Section 3.62), good site
practices and dust monitoring and audit programme, acceptable dust impact would
be expected at the ASRs. Details of the
monitoring requirements such as monitoring locations, frequency of baseline and
impact monitoring are presented in the stand-alone EM&A Manual.
Operation Phase
3.67
No adverse air quality impact on the ASRs was identified during operational phase
of the Project after relocation of the fresh air intakes of ASRs A4, A5 and A6.
Notwithstanding this, post-project air quality monitoring is recommended to be
carried out for the area underneath the Atrium Link Extension. Details of the
monitoring requirements such as monitoring locations, frequency of baseline and
impact monitoring are presented in the stand-alone EM&A Manual.
Construction Phase
3.68
In view of limited scale of construction areas and less dusty construction activities, negligible
dust impact would be expected with the implementation of appropriate mitigation
measures and good site practices. An
EM&A programme during construction has been recommended to monitor the
effectiveness of the proposed dust suppression measures.
Operation Phase
3.69
The cumulative air quality impact under both Long-term
scenario and Interim scenario were assessed.
Results showed that the predicted air quality at the surrounding ASRs
and the area underneath the Atrium Link Extension would comply with the AQOs in
the Interim Scenario. In view of
provision of good indoor air quality, it is recommended to re-divert the fresh
air intakes of Renaissance
Harbour View Hotel (ASR A4), Hong Kong Convention and Exhibition Centre Phase I
(ASR A5) and Grand Hyatt Hotel (ASR A6) located underneath the deck to the new
fresh air intake provided for the New Atrium Link Extension.
3.70
In the Long-term Scenario, results indicated that the
air quality at the representative ASRs except fresh air intakes of Renaissance Harbour View Hotel (ASR
A4), Hong Kong Convention and Exhibition Centre Phase I (ASR A5) and Grand
Hyatt Hotel (ASR A6) would comply with the AQOs. The affected fresh air intakes are
recommended to re-divert to the new fresh air intake provided for Atrium
Link Extension. The air
quality underneath the Atrium Link Extension would comply with the EPD Tunnel
Air Quality Guidelines but would not comply with the AQO. According to the current Draft Wan Chai North
Outline Zoning Plan, the planned land use underneath the Atrium Link Extension
is “Road”. However, in view of exceedance of AQO, the area underneath the
Atrium Link Extension would not be suitable for placing any air sensitive
receivers.