5.
AIR QUALITY IMPACT
5.1
Assessment on the potential air quality 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 air quality impacts on
these ASRs arising from dust emission from construction work sites, stockpiles
and barging facilities have been assessed and appropriate mitigation measures
are proposed to alleviate the potential air quality impacts.
5.2
The trains to be employed for the 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 be
carefully positioned to avoid nuisance to the surrounding environment.
Environmental Legislation, Standards and
Guidelines
5.3
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 Objective & EIAO-TM
5.4
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 5.1.
Table 5.1
|
Pollutant |
Maximum Concentration
(µg/m3) (1) |
||||
|
Averaging Time |
|||||
|
1 hour(2) |
1 hour(2) |
1 hour(2) |
1 hour(2) |
1 hour(2) |
|
|
- |
- |
260 |
- |
80 |
|
|
Respirable Suspended Particulates
(RSP) (5) |
- |
- |
180 |
- |
55 |
|
Sulphur Dioxide (SO2) |
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 |
|
Note:
(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.
5.5
The EIAO-TM stipulates that the hourly TSP level should not
exceed
Air Pollution Control (Construction Dust) Regulation
5.6
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, etc. This
Project is expected to include notifiable works (foundation, superstructure
construction and demolition) and regulatory works (temporary stockpile, dusty
material handling and excavation).
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.
Description
of the Environment
5.7
The Project alignment branches
out from the existing East Rail tracks south of Mong Kok East Station (MKK) to
the new Hung Hom Station (HUH) east of the current station. The locality of the Project area is a
developed urban area with major land uses including residential, commercial and
educational institutes.
5.8
In accordance with the Guidelines
in Assessing the ‘TOTAL’ Air Quality Impacts, both Mong Kok and Hung Hom areas
are categorized as urban area.
Since there is no EPD general air quality monitoring station located in
these areas, the recent five years (2006 –2010) annual average monitoring data
recorded at EPD’s general air quality monitoring stations in urban areas are
therefore taken to estimate the background concentration for the purpose of
this assessment. With reference to EPD’s
Air Quality Annual Report, the EPD’s general air quality monitoring stations in
urban areas considered in this assessment include Central/Western, Kwun Tong,
Sham Shui Po, Tsuen Wan and Kwai Chung.
The annual average air pollutant
concentrations recorded at these monitoring stations are presented in Table
5.2. The background concentration adopted for
this assessment is estimated as the mean of these annual average concentrations
as shown in the table.
Table 5.2 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.
5.9
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 ASRs. As stated
in the EIA Study Brief, the boundary of the assessment area for air quality
assessment should be
5.10
The proposed alignment would
generally be built by cut-and-cover method, and the associated construction
works would mostly be at or below existing ground level. The lowest assessment height was
therefore taken as either at
Table 5.3 Representative
Air Sensitive Receivers
|
ASRs |
Description |
Land Use |
Distance from the nearest emission sources (m) |
No. of storey |
Assessment Height (m AGL) |
|
OMA2 |
Parc Palais, Block 6 |
Residential |
115 |
24 |
1.5, 5, 10, 15 & 20 |
|
OMA3 |
Parc Palais, Block 3 |
Residential |
145 |
24 |
1.5, 5, 10, 15 & 20 |
|
OMA4 |
|
Education Institution |
60 |
5 |
1.5, 5, 10, 15 & 20 |
|
OMA5 |
King's Park Sport Ground |
Recreational |
65 |
0 |
1.5 |
|
HHA1 |
|
Residential |
140 |
20 |
1.5, 5, 10, 15 & 20 |
|
HHA2 |
|
Residential |
40 |
8 |
1.5, 5, 10, 15 & 20 |
|
HHA3 |
PolyU Cheung On Tak Lecture Theatre |
Education Institution |
70 |
6 |
1.5, 5, 10, 15 & 20 |
|
HHA4 |
|
Commercial |
40 |
10 |
1.5, 5, 10, 15 & 20 |
|
HHA5 |
The Metropolis Residence |
Service Apartment |
185 |
18 |
1.5, 5, 10, 15 & 20 |
|
HHA6 |
|
Hotel |
55 |
11 |
1.5, 5, 10, 15 & 20 |
|
HHA7 |
Fire Service Headquarters |
GIC |
165 |
13 |
1.5, 5, 10, 15 & 20 |
|
HHA8 |
|
GIC |
90 |
1 |
10, 15 & 20 |
|
HHA9 |
Harbourfront Horizon# |
Service Apartment |
25 |
22 |
5, 10, 15 & 20 |
|
HHA10 |
|
Residential |
115 |
17 |
1.5, 5, 10, 15 & 20 |
Notes:
* - 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.
# - No
air sensitive use was observed at the ground level, assessment height was taken
as the first floor level at 5m AGL.
5.11
The Project alignment is an approximately 1.2km extension
branches out from the existing East Rail Line (EAL) tracks from the tunnel
portal near Oi Man Estate (Portal
5.12
Major construction works that would contribute to
construction dust impacts include cut and cover works for tunnel and surface
works; construction
of superstructures including the
ventilation shafts;
modification work to HUH podium structure; loading/unloading at barging point. The tentative working hours will
be 07:00 to 19:00 from Monday to Saturday for all works sites including the
barging point. Locations of the
construction works areas including cut and cover work sites and barging point
are illustrated in Figure
No. NEX2213/C/361/ENS/M60/501. Details
of the construction activities and potential emission sources for the selected
construction method are described in the following sections.
5.13
Alternative construction
methods/phasing programme that have previously been reviewed and examined for
the Project are described in Section 2 of this report.
Tunnel
5.14
Tunnel construction for the Project would be carried
out by cut-and-cover
method. The major potential dust impacts above
ground would be dust arising from excavation, material handlings
and transportation of spoils on paved haul roads within the
site.
5.15
The proposed alignment from portal
5.16
Some existing superstructures
located directly above the cut-and-cover tunnel would be demolished before the
construction of the tunnel. Dust
arising from demolishing reinforced concrete structure would be limited. With the implementation of
dust suppression measures stipulated in Air Pollution Control (Construction
Dust) Regulation, adverse dust impact associated
with the demolition works would not be expected.
5.17
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 work
site area.
Therefore, adverse dust impact from the transportation of spoil would
not be anticipated. Besides, 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 the dusty materials would be
covered entirely before leaving the work site, the dust nuisance
from construction vehicle movement outside the work site is unlikely to be
significant.
Ventilation Shafts
5.18
Some ventilation shafts
would be built at the north and south of HUH podium edge for
the operational tunnel and station ventilation. The construction areas for these
superstructures would be limited, and all
structures are reinforced concrete in
nature. Adverse dust
impacts arising from construction of ventilation shafts are not anticipated
with the implementation of dust suppression measures stipulated in Air
Pollution Control (Construction Dust) Regulation.
Modification Works to Existing HUH Podium Structure
5.19
Modification works to the
existing HUH podium structure would be carried out to introduce openings for
new escalators, lifts and stairs and also to provide sufficient headroom for
the mid-Level walkway, E&M provisions and also works resulting from the re-configuration
and removal of existing columns of the Freight Terminal. The modification works would only
involve minor excavation work of which most are carried out in an enclosed
environment to minimise the disturbance to the public and railway operations. Adverse dust impacts arising from the
modification works to the existing HUH podium structure are not anticipated with the implementation
of dust suppression measures stipulated in Air Pollution Control (Construction
Dust) Regulation.
Barging Point
5.20
One barging point with two loading ramps at Hung
Hom Freight Pier, constructed under KTE project would be used during the
construction of the SCL projects.
It would be operated for 12 hours a day (07:00 to 19:00) on
normal working days except the typhoon No.3 or above hoist. The excavated materials produced during
the construction of the proposed SCL Alignment would be transported to the
tipping halls of the barging point by trucks and then unloaded to the barges. No stockpile area would be provided for
the barging point.
5.21
The haul roads within the barging point 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. To alleviate the
potential dust impacts, the dusty materials on the trucks would be well covered
and flexible dust curtain would be provided
at the loading points (from the berths of barging point to the barges). The barging facilities would be share
used by this Project, SCL (HUH – ADM), SCL (TAW – HUH) and KTE.
Railway Reprovisioning Works of Homantin Siding
5.22
Homantin Siding, the former
livestock sidings area located at the south side of Chatham Road Interchange,
would be reserved for railway reprovisioning works. Only minor excavation works, e.g.
realignment of the existing rail track and relocation of the crossing, would be
carried out. No potential dust impact would, therefore, be expected.
Other Construction Works
5.23
Apart from the above construction
works, there are some minor supporting works, including demolition works, pile
removal, stormwater drain, culvert diversion and other improvement works for
Viaducts, for the Project. The
potential dust impacts from these activities are localized and the extent of
excavated areas would be limited. Adverse dust impacts are,
therefore, not anticipated with the implementation of dust suppression measures
stipulated in Air Pollution Control (Construction Dust) Regulation.
Off-site Area at MKK Freight Yards
5.24
Minor modification works
for office/store layout would be carried out inside the current freight yard
underneath MKK podium. No potential
dust impact would be expected.
Cumulative Dust Impact from Other Concurrent Projects
5.25
Based on the current programme,
the Project would likely have interactions with some other projects, including
SCL (HUH – ADM), SCL (TAW – HUH) and KTE.
SCL (HUH – ADM)
5.26
SCL (HUH – ADM) starts from the
north of the proposed NOV across the harbour to new stations at Exhibition and
Admiralty. The construction of SCL
(HUH – ADM) at Hung Hom would be carried out concurrently with the
Project. The construction of
tunnels at Hung Hom would be generally carried out by cut-and-cover method near
the waterfront. In addition, the
existing
SCL (TAW – HUH)
5.27
The SCL (TAW – HUH) is an
extension of Ma On Shan Line from Tai Wai 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 addressed in the SCL (TAW – HUH) EIA Report and it is also
summarized in Appendix 5.3.
5.28
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, located next
to the Project boundary, would be constructed by open excavation method and
potential dust impacts would be expected.
Two rock crushing facilities and one barging point with two loading
ramps located at Hung Hom Freight Pier are required to be constructed and
operated during the construction of KTE.
The barging facilities would be share among this Project,
SCL (HUH – ADM), SCL (TAW – HUH) and KTE.
Thus, potential cumulative dust impacts arising from the operation of the rock crushing facilities
and barging point are expected. The
detailed assessment methodology is addressed in the KTE EIA Report and it is
also summarized in Appendix
5.4.
5.29
Any above-ground major construction activity arising
from SCL (HUH – ADM), SCL (TAW – HUH) and KTE within
Operation Phase
5.30
During operation of the Project,
no air pollutant emissions would be generated from the electrical trains. The ventilation shafts connecting to the
ventilation system of the station would only emit carbon dioxide (CO2)
generated from the breathing of the passengers and staff. The ventilation system is designed for
an air exchange rate of 5 litre/person/second in accordance with MTR Design
Manual. As a result, all CO2
would be exhaled by normal air exchange.
Similar to other electrical rail projects with substantial underground
sections (e.g. Express Rail Link and Kowloon Southern Link), air quality impact
from the operations of ventilation shafts would not be considered as a key
environmental issue.
5.31
With regards to the future
operations, freight train (with diesel locomotive) operation will be winded
down, and intercity service would remain the same in fairly low frequency. Thus, there will be less emission
generated from diesel locomotives as compared to the current situation. No additional particulate emission
associated with diesel combustion is therefore anticipated.
5.32
One of the works items is to
realign the Cheong Wan Road Viaduct.
The section of Cheong Wan Road Viaduct connecting HUH and
·
To the east of the road – the
nearest ASRs are Metropolis Residence and
·
To the west of the road – the
nearest ASR is Hong Kong Polytechnics University (HKPU) which has been provided
with a central fresh air supply system to minimize any roadside effect. The new Cheong Wan Road Viaduct would be
shifted insignificantly towards the HKPU by 10m as compared to the original
distance of 110m. The impact will
be minimal as compared to the recommended setback distance of 5m from local
distributor in accordance with the Hong Kong Planning Standard and Guidelines (HKPSG).
·
To the south of the road – the
nearest ASR is HUH. There is no change in the setback distance as compared to
the existing alignment. As the ASRs
are more than 75m away from the road, vehicular impact arising from the
realigned Cheong Wan Road Viaduct would expect to be
negligible in accordance with the HKPSG Guidelines.
·
To the north of the road – the
nearest ASR is On Tai Mansion.
Similarly, the ASRs are more than 150m away and there is no change to
the setback distance as compared to the existing alignment. Therefore, vehicular impact arising from
the realigned Cheong Wan Road Viaduct would not be a concern.
5.33
Referring to the above sections, major potential dust
impacts would be expected from the construction of cut-and-cover tunnel and the
operation of the barging point at Hung
Hom Freight Pier. Quantitative assessment is therefore
conducted for these construction works. The
potential dust emission sources considered in the assessment are shown in NEX2213/C/361/ENS/M60/512 under Appendix
5.1.
5.34
Regarding the construction of ventilation shafts at HUH and
the modification works to existing HUH podium structure, there would only be
limited dusty construction activities involved and any excavation works and/or
spoil loading/unloading would all be undertaken within enclosed structure. Therefore, 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. The potential dust impacts arising from these works
areas are addressed qualitatively in this study.
Emission Inventory
5.35
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
5.36
According to United States Environmental Protection Agency
(USEPA) AP-42[1], construction dust particles may be grouped into five
particle size classes. Their size
ranges are 1.25 mm,
3.75 mm, 7.5 mm, 12.5 mm,
22.5 mm, and the percentage of
particles in each class was estimated to be 7%, 20%, 20%, 18% and 35%,
respectively.
5.37
Predicted dust emissions are based on emission factors from AP-42. The major
dusty construction activities for the Project that have been considered in the
modelling assessment include:
(A) Tunnel Cut &
Cover areas
-
Excavation and material handling
within the construction site were modelled as heavy construction activities
-
Wind erosion of open active site
(B) Barging Point
(share used facilities, the design has been updated in this study as compared
to the approved KTE EIA Report)
-
Transportation of the spoils to
the enclosed tipping hall of the barging point was modelled as heavy
construction activities
-
Unloading point to the barge
5.38
According to the preliminary engineering design information,
dust control measures have been incorporated into the design of the barging
facilities, as presented in Tables 5.4. These dust control measures have also
been taking into account in the assessment.
Table 5.4 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. |
5.39
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
concentrations. The justification
for the percentage of annual average active area is presented in Appendix 5.5.
5.40
Whereas for predicting hourly and daily average TSP levels,
a more conservative approach is adopted.
It is assumed that the whole construction site would be 100% actively
operated, notwithstanding such a scenario would unlikely occur.
5.41
The emission rates of identified pollutant sources are
summarised in Tables 5.5
and 5.6. Detailed calculations of the emission
factors are given in Appendix 5.1.
Table 5.5 Emission
Factors for Dusty Construction Activities
|
Emission Source |
Activity |
Emission Rate |
Remarks |
|
North
Approaching Tunnel Construction
(Cut & Cover Areas and Stockpile Areas) |
Heavy Construction Activities |
E=2.69 Mg/hectare /month of activity |
|
|
|
Wind Erosion |
E=0.85Mg/hectare /year |
|
|
South
Approaching Tunnel Construction
(Cut & Cover Areas and Stockpile Areas) |
Heavy Construction Activities |
E=2.69 Mg/hectare /month of activity |
|
|
|
Wind Erosion |
E=0.85Mg/hectare /year |
|
Table 5.6 Emission
Factors for Barging Facilities
|
Emission Source |
Activity |
Emission
Rate |
Remarks |
|
Barging Point at Hung Hom Freight Pier |
Unloading of spoils to barge |
E=3.42
x 10-4 kg/Mg |
|
|
Paved haul road -transport the spoil from the construction sites to
the barging point (modelled as heavy construction) |
E=2.69
Mg/hectare /month
of activity |
|
5.42
Twelve working hours per day on normal working days was
assumed for the above-mentioned construction activities during 07:00
to 19:
Dispersion Modelling & Concentration Calculation
5.43
Fugitive Dust Model (FDM) (1993 version) was adopted to
assess potential dust impact from the construction works. The height of
5.45
Since no construction activities
would occur on Sundays and public holidays, only wind erosion would be assumed
for these days as well as for other non-working hours (19:00 to 07:00 of the
following day) on normal working days.
5.46
As mentioned in Section
5.8, the background TSP
level of 75.2 mg/m3,
estimated based on the latest five years average monitoring data recorded
at EPD’s urban
general air quality monitoring stations, was adopted as the future TSP
background concentration for this assessment.
5.47
As there is no significant air
quality impact identified during operation of the Project, only qualitative
approach is adopted to address the air quality implications.
Prediction and Evaluation of Impacts
Unmitigated Scenario
5.48
The predicted unmitigated cumulative maximum hourly,
daily and
annual average TSP concentrations at the representative ASRs are
summarized in Table
5.7. The
contour plots at 1.5m AGL are presented in Figure Nos. NEX2213/C/361/ENS/M60/514 - NEX2213/C/361/ENS/M60/516.
Table 5.7 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 |
||
|
1.5 |
1237 |
405 |
77.3 |
|
|
|
5 |
1029 |
355 |
77.2 |
|
|
10 |
673 |
236 |
76.8 |
|
|
15 |
406 |
162 |
76.5 |
|
|
20 |
335 |
125 |
76.2 |
|
OMA3 |
1.5 |
844 |
342 |
78.1 |
|
|
5 |
763 |
324 |
78.0 |
|
|
10 |
508 |
249 |
77.4 |
|
|
15 |
340 |
184 |
76.9 |
|
|
20 |
286 |
141 |
76.5 |
|
OMA4 |
1.5 |
1837 |
245 |
77.6 |
|
|
5 |
1464 |
203 |
77.2 |
|
|
10 |
775 |
154 |
76.6 |
|
|
15 |
505 |
131 |
76.4 |
|
|
20 |
375 |
118 |
76.2 |
|
OMA5 |
1.5 |
1217 |
523 |
81.5 |
|
HHA1 |
1.5 |
895 |
320 |
79.3 |
|
|
5 |
736 |
275 |
79.0 |
|
|
10 |
425 |
186 |
78.0 |
|
|
15 |
333 |
152 |
77.2 |
|
|
20 |
252 |
135 |
76.6 |
|
HHA2 |
1.5 |
1939 |
424 |
79.3 |
|
|
5 |
1580 |
249 |
77.8 |
|
HHA2 |
10 |
832 |
172 |
76.7 |
|
|
15 |
468 |
144 |
76.4 |
|
|
20 |
345 |
138 |
76.1 |
|
HHA3 |
1.5 |
1755 |
754 |
84.8 |
|
|
5 |
989 |
468 |
82.4 |
|
|
10 |
524 |
207 |
78.9 |
|
|
15 |
345 |
168 |
77.3 |
|
|
20 |
281 |
144 |
76.5 |
|
HHA4 |
1.5 |
2515 |
679 |
81.1 |
|
|
5 |
1381 |
398 |
79.1 |
|
|
10 |
790 |
246 |
77.2 |
|
|
15 |
439 |
182 |
76.5 |
|
|
20 |
331 |
141 |
76.1 |
|
HHA5 |
1.5 |
1366 |
295 |
76.8 |
|
|
5 |
1248 |
285 |
76.8 |
|
|
10 |
836 |
228 |
76.5 |
|
|
15 |
494 |
178 |
76.2 |
|
|
20 |
373 |
145 |
76.0 |
|
HHA6 |
1.5 |
810 |
242 |
83.3 |
|
|
5 |
802 |
242 |
81.1 |
|
|
10 |
653 |
213 |
78.6 |
|
|
15 |
488 |
179 |
77.4 |
|
|
20 |
346 |
150 |
76.7 |
|
HHA7 |
1.5 |
546 |
195 |
89.1 |
|
|
5 |
549 |
198 |
88.8 |
|
|
10 |
468 |
180 |
86.2 |
|
|
15 |
375 |
159 |
83.5 |
|
|
20 |
288 |
139 |
81.2 |
|
HHA8 |
10 |
705 |
200 |
78.0 |
|
|
15 |
502 |
166 |
77.1 |
|
|
20 |
339 |
138 |
76.6 |
|
HHA9 |
5 |
707 |
254 |
97.8 |
|
|
10 |
560 |
190 |
85.0 |
|
|
15 |
452 |
159 |
80.2 |
|
|
20 |
352 |
137 |
78.2 |
|
HHA10 |
1.5 |
1044 |
223 |
77.2 |
|
|
5 |
919 |
205 |
77.1 |
|
|
10 |
556 |
162 |
76.6 |
|
|
15 |
362 |
132 |
76.3 |
|
|
20 |
284 |
121 |
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
(3) Boldfaced value presents the predicted
TSP concentration exceed the respective criteria.
5.49
Based on the results shown in Table 5.7
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.
Hence, proper dust mitigation measures should be implemented.
Recommended Air Quality Mitigation Measures
5.50
In order to minimise the
construction dust impact, the following dust mitigation measures should be
implemented:
Ÿ
Watering once every working hour on the active works areas,
exposed areas and paved haul roads to reduce dust emission by 91.7%[2]. 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
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 1.7L/m2 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.
Ÿ
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%[3];
and
5.51
In addition to the dust control measures described above,
dust suppression measures stipulated in the Air Pollution Control (Construction
Dust) Regulation and good site practices listed below should be carried out to
further minimize construction dust impact:
Ÿ
Use of regular watering to reduce dust emissions from
exposed site surfaces and unpaved roads, particularly during dry weather.
Ÿ
Use of frequent watering for particularly dusty construction
areas and areas close to ASRs.
Ÿ
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.
Ÿ
Tarpaulin covering of all dusty vehicle loads transported
to, from and between site locations.
Ÿ
Establishment and use of vehicle wheel and body washing
facilities at the exit points of the site.
Ÿ
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.
Ÿ
Provision of not less than
Ÿ
Imposition of speed controls for vehicles on site haul
roads.
Ÿ
Where possible, routing of vehicles and positioning of
construction plant should be at the maximum possible distance from ASRs.
Ÿ
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.
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.
Mitigated Scenario
5.52
The predicted mitigated cumulative maximum hourly, daily and
annual average TSP concentrations at the representative ASRs during
construction are summarized in Table 5.8.
Table 5.8 Predicted
Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative
Air Sensitive Receivers (Mitigated)
|
ASRs |
Assessment Height (mAGL) |
Cumulative Maximum TSP Concentrations in mg/m3 |
||
|
Hourly Average |
24-hour Average |
Annual Average |
||
|
OMA2 |
1.5 |
273 |
148 |
76.2 |
|
|
5 |
250 |
142 |
76.2 |
|
|
10 |
191 |
123 |
76.1 |
|
|
15 |
149 |
109 |
76.0 |
|
|
20 |
141 |
100 |
75.9 |
|
OMA3 |
1.5 |
245 |
130 |
76.2 |
|
|
5 |
232 |
127 |
76.3 |
|
|
10 |
190 |
115 |
76.1 |
|
|
15 |
153 |
104 |
76.0 |
|
|
20 |
141 |
96 |
75.9 |
|
OMA4 |
1.5 |
291 |
141 |
76.4 |
|
|
5 |
258 |
134 |
76.3 |
|
|
10 |
179 |
121 |
76.2 |
|
|
15 |
170 |
113 |
76.1 |
|
|
20 |
159 |
106 |
76.1 |
|
OMA5 |
1.5 |
337 |
161 |
76.9 |
|
HHA1 |
1.5 |
314 |
140 |
76.5 |
|
|
5 |
286 |
137 |
76.5 |
|
|
10 |
236 |
122 |
76.2 |
|
|
15 |
202 |
111 |
76.0 |
|
|
20 |
176 |
105 |
75.9 |
|
HHA2 |
1.5 |
439 |
202 |
77.0 |
|
|
5 |
263 |
149 |
76.4 |
|
|
10 |
252 |
139 |
76.1 |
|
|
15 |
282 |
144 |
76.0 |
|
|
20 |
269 |
138 |
75.9 |
|
HHA3 |
1.5 |
317 |
161 |
76.9 |
|
|
5 |
291 |
152 |
76.6 |
|
|
10 |
237 |
133 |
76.1 |
|
|
15 |
199 |
119 |
75.8 |
|
|
20 |
174 |
111 |
75.7 |
|
HHA4 |
1.5 |
324 |
161 |
76.5 |
|
|
5 |
262 |
138 |
76.2 |
|
|
10 |
177 |
117 |
75.9 |
|
|
15 |
167 |
109 |
75.7 |
|
|
20 |
158 |
103 |
75.6 |
|
HHA5 |
1.5 |
220 |
118 |
75.8 |
|
|
5 |
213 |
117 |
75.8 |
|
|
10 |
180 |
110 |
75.7 |
|
|
15 |
154 |
104 |
75.6 |
|
|
20 |
148 |
98 |
75.6 |
|
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 |
|
HHA8 |
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 |
|
HHA10 |
1.5 |
254 |
127 |
76.1 |
|
|
5 |
227 |
122 |
76.1 |
|
|
10 |
205 |
119 |
76.0 |
|
|
15 |
205 |
117 |
75.9 |
|
|
20 |
188 |
112 |
75.8 |
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
5.53
Based on the results shown in Table 5.8, 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 the
implementation of 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/361/ENS/M60/502 -
NEX2213/C/361/ENS/M60/504. 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 Nos. NEX2213/C/361/ENS/M60/505 - Nos.
NEX2213/C/361/ENS/M60/507.
5.54
Some exceedances of hourly, daily
and annual average TSP concentrations were predicted at the slope near to
Chatham Road North Interchange, the railway track at north of the HUH, the
freight pier on the contour plots.
However, there is no air sensitive use at these areas and no adverse
impact is anticipated. The hourly
average TSP concentration at the rest garden and playground near the Chatham
Road North Interchange and the annual average TSP concentration at
5.55
There is no adverse air quality
impact expected from the operation of the Project as discussed in Sections 5.30 - 5.32 above.
Evaluation of Residual Impacts
5.56
With the implementation of the mitigation measures as
stipulated in the Air Pollution Control (Construction Dust) Regulation as well
as the recommended dust control measures and good site practices, no adverse
residual air quality impact would be expected.
5.57
As the freight train operation
would be winded down and the intercity operation mode would remain the same but
in fairly low frequency, less emission generated from operation of the existing
diesel locomotives would be expected.
Thus, insignificant air quality impact from operation of diesel
locomotives along the existing East Rail is anticipated.
Environmental Monitoring and Audit Requirements
5.58
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.
5.59
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
as well as the recommended dust suppression measures and good site practices, no
adverse dust impact on the ASRs in the vicinity of the construction sites would
be anticipated.
5.60
As the train will be electrically operated, air quality
impact is therefore not anticipated during operational phase. Besides, no adverse air quality impact
is expected from the operation of realigned Cheong Wan Road Viaduct and
reduction in the number of the existing diesel locomotives (for maintenance
trains/intercity) along the existing East Rail. Exhausts for general ventilation and
smoke extraction facilities will also be carefully positioned to avoid nuisance
to the surrounding environment.