4.
AIR
QUALITY
4.1
Introduction
4.1.2 The operation of Sha Tin WTW does not involve any air polluting
activities, air quality impact is therefore not anticipated during operation
phase of the Project and will not be assessed in
this section.
4.2.2 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 relevant AQOs are listed in Table
4.1.
Table 4.1 Hong
Kong Air Quality Objectives
Pollutants
|
Averaging Time
|
Concentration Limit (µg/m3)
|
No. of Exceedances to be Allowed per Calendar Year
|
Respirable Suspended Particulates
(RSP) (1)
|
24-hour
|
100
|
9
|
1-year
|
50
|
Not
applicable
|
Fine Suspended Particulates (FSP) (2)
|
24-hour
|
75
|
9
|
1-year
|
35
|
Not applicable
|
Note:
(1)
RSP means suspended particles in air with a nominal
aerodynamic diameter of 10 µm or less.
(2)
FSP means
suspended particles in air with a nominal aerodynamic diameter of 2.5 µm or
less.
4.2.3 Annex 4 of the EIAO-TM stipulates that the hourly Total Suspended
Particulates (TSP) level should not exceed 500 mgm-3 (measured at 25ºC and
one atmosphere) for construction dust impact assessment.
4.2.4 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 both notifiable works and regulatory works. 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.
Background Air Quality
4.3.2 With reference to EPD’s Air Quality Annual Report, the recent five
years (2009 – 2013)
annual average particulate matter concentrations recorded at EPD’s
air quality monitoring station closest to the Project site, namely the Shatin
station, are presented in Table 4.2. The long-term (5-year)
average of these annual average monitoring data obtained by EPD at the Shatin
station is taken as the background concentration for the Project site in
accordance with EPD’s Guidelines on Assessing the ‘TOTAL’ Air Quality Impacts.
Table 4.2 Annual Average Pollutant Concentration in the Latest Five Years (Year 2009 – 2013) at Shatin Air
Quality Monitoring Station
Pollutant
|
Annual Average Concentration
(μg/m3)
|
Background
Concentration (μg/m3)
|
2009
|
2010
|
2011
|
2012
|
2013
|
TSP
|
60
|
67
|
66
|
54
|
57
|
60.8
|
RSP
|
45
|
45
|
47
|
39
|
42
|
43.6
|
FSP
|
N/A
|
N/A
|
N/A
|
26
|
29
|
27.5*
|
Remarks:
-
N/A indicate data not
available.
-
Asterisk indicates background concentration
calculated from the available data (year 2012 and 2013) only.
-
FSP concentrations were not available for
years earlier than 2012.
Table 4.3 Representative Air Sensitive Receivers
ASRs
|
Description
|
Land
Use
|
Distance from the Project Boundary (m)
|
No. of Storey
|
ASR-1
|
The Blossom Phase 4
|
Residential
|
100
|
2
|
ASR-2
|
The L Louey
|
Residential
|
25
|
2
|
ASR-3
|
Hin Keng Estate -
Hin
Yau House
|
Residential
|
95
|
35
|
ASR-4
|
Hin Keng Estate -
Hin
Wan House
|
Residential
|
115
|
35
|
ASR-5
|
Hin Keng Estate -
Hin
Kwai House
|
Residential
|
145
|
35
|
ASR-6
|
Sha Tin
Height Tunnel Administration Building
|
Office
|
180
|
3
|
4.4
Identification of
Environmental Impacts
4.6
Prediction and
Evaluation of Environmental Impacts
4.6.1 The construction of the Project would commence in 2015 for
completion in early-2021 (see
construction programme in Appendix 2.1). The total construction programme is about 70 working months. According
to the current construction programme, the demolition and construction works
are scheduled to be conducted in sequence. Some of the construction tasks would
be carried out concurrently. Details of
the major dusty construction activities are discussed below and the locations
of the dusty construction activities are shown in Figures 4.2 and 4.3.
Excavation Works
4.6.2
The most dusty construction
activities would likely be excavation works.
Excavation works would be required for the construction of the retaining
wall and new access road, Water Treatment Works Logistics Centre,
washwater recovery tanks, Pre-ozonation House, Flocculation Tanks, High Rate Sedimentation Tanks,
Intermediate Ozonation House, Stage 2 Granular Media Filters.
These excavation works would be carried out over a reasonable period
to minimise the daily excavated volume.
With the small volume of excavated materials to be generated daily and
disposed off-site, the potential dust impact at the nearby ASRs shall not be
significant with the effective implementation of good site practices and dust
suppression measures stipulated in Air Pollution Control (Construction Dust)
Regulation.
Demolition of Existing Structures
4.6.3
The demolition works of the
existing South Works including chemical house, washwater recovery tanks and
administration building would each take about 3 to 18 months. Given the short duration and small scale of
the demolition works and with the implementation of dust suppression measures
stipulated in Air Pollution Control (Construction Dust) Regulation together with good site practices, the potential dust impact would be
minimal. No adverse dust impacts on the
nearby ASRs would be anticipated.
Cumulative Dust Impacts with Concurrent Project
4.6.4
It is noted that the
construction period of the Shatin to Central Link – Tai Wai to Hung Hom Section
[SCL(TAW-HUH)] would overlap with the construction period of this Project.
4.6.5
The SCL (TAW – HUH) is an
extension of Ma On Shan Line from Tai Wai through the new stations in the east
Kowloon, and connecting the West Rail Line (WRL) at Hung Hom Station. According
to the approved EIA report of SCL(TAW-HUH) (AEIAR-167/2012), the construction
works of SCL(TAW-HUH) near Hin King area, including the alignment at Hin Keng
and the Hin Keng Station, would commence in 2012 and be completed by June 2016.
As the Project would commence in August 2015, there might be cumulative
construction dust impacts in the vicinity of the study area during August 2015 to
June 2016.
4.6.6
The tentative construction
methods of SCL(TAW-HUH) near Hin Keng area include cut-and-cover tunnel
construction and at-grade construction of Hin Keng Station and SCL(TAW-HUH)
alignment. Potential dust impacts would be expected. Yet, dust suppression
measures would be implemented for the SCL(TAW-HUH) project, and as such, no unacceptable construction dust
impact was predicted under the SCL(TAW-HUH) EIA study.
4.6.7
The construction programme provided in the approved SCL(TAW-HUH) EIA
report indicated that the peak construction period for Hin Keng area would occur
in year 2013 to 2014, and this peak construction period was referred as worst-case
scenario in the EIA study for prediction of air quality impacts. However, the concurrent
period for SCL(TAW-HUH) and the Project will be less than a year, from August
2015 to June 2016. Prior to this period, the majority of dusty construction
works at Hin Keng area, including most of the bulk excavation would have been
finished. During the concurrent period, the construction works of SCL(TAW-HUH)
would mainly involve only minor dusty works, such as structural element casting
and E&M installation. Therefore, it is expected that the dust generated
from SCL(TAW-HUH) during the concurrent period would be much less than that
predicted under the worst-case scenario as presented in the approved EIA.
4.6.8
On the other hand, with reference to the construction programme of the
Project in Appendix
2.1, during the concurrent period, only minor construction works would
be carried out, including construction of haul road and the associated
retaining wall. The other construction activities, including demolition of
existing Sha Tin WTW, excavation and construction of various buildings would be
started after the construction of SCL(TAW-HUH) is completed in June 2016. Therefore,
adverse cumulative construction dust impact from the two projects is not
anticipated during the concurrent period of August 2015 to June 2016.
4.6.9
Since the scale of this Project is minimal comparing with SCL(TAW-HUH), the amount
of dust generation from this Project would be minimal, adverse construction dust impact from the Project alone is also not
anticipated.
4.7.1 To ensure compliance with the relevant standards, dust suppression
measures stipulated in the Air Pollution Control (Construction Dust) Regulation
and good site practices should be incorporated into the contract document to
control potential dust emission from the site.
The major dust suppression measures include:
·
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 stockpiling of dusty
material to reduce emissions. Where this
is not practicable owing to frequent usage, watering shall be applied to
aggregate fines.
·
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 not less than 2.4 m high hoarding from
ground level along site boundary where adjoins a road, streets or other areas 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.
·
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.
4.8
Evaluation of
Residual Environmental Impacts
4.8.1 With the implementation of the dust suppression measures stipulated
in the Air Pollution Control (Construction Dust) Regulation, no adverse
residual dust impact would be expected.
4.9
EM&A
Requirements
4.9.1 Environmental monitoring and audit for potential dust impacts 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.
4.10
Conclusion
4.10.1 Potential air quality impacts from the construction works of the Project
would mainly be related to construction dust from excavation, materials
handling, spoil removal, demolition and wind erosion. In view of the nature of works, adverse dust
impact at the ASRs would not be expected from the Project. Nevertheless, appropriate dust suppression
measures as stipulated in the Air Pollution Control (Construction Dust)
Regulation should be implemented to minimize any potential dust impact.
~
End of Section 4 ~