4.1
Purpose of the Assessment
This section presents the air quality impact
assessment for the construction and operational phases of the Project.
4.2
Relevant Legislation and Guidelines
The principal legislation for the management of air
quality is the Air Pollution Control
Ordinance (APCO) Cap 311. The whole
of the Hong Kong Special Administrative Region is covered by the Hong Kong Air
Quality Objectives (HKAQOs) which stipulate the
statutory limits of some typical air pollutants and the maximum allowable
number of exceedances over specific periods. The HKAQOs are
shown in Table 4.1 below.
Table 4.1
|
Air Pollutant |
Concentration in micrograms per cubic metre (a) |
|||
|
|
Averaging Time |
|||
|
|
1 Hour (b) |
8 Hours (c) |
24 Hours (c) |
1 Year (d) |
|
Total Suspended
Particulates (TSP) |
- |
- |
260 |
80 |
|
Respirable Suspended Particulates
(RSP) (e) |
- |
- |
180 |
55 |
|
|
800 |
- |
350 |
80 |
|
Nitrogen Dioxide (NO2) |
300 |
- |
150 |
80 |
|
Carbon Monoxide (CO) |
30,000 |
10,000 |
- |
- |
|
Notes: (a) Measured at 298K (25°C) and 101.325 kPa
(one atmosphere). (b) Not to be exceeded more
than three times per year. (c) Not to be exceeded more
than once per year. (d) Arithmetic means. (e) Respirable suspended particulates
mean suspended particles in air with a nominal aerodynamic diameter of 10
micrometers and smaller. |
||||
In addition, the Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM) has also
set an hourly TSP criterion of 500 µgm-3 for use
in the construction dust assessment.
There is no statutory guideline for open-air car
park, and therefore there is no specific requirement for the car park
provision.
4.3
Baseline Conditions and Background Air Quality
The Development Site is located at Sha Lo Tung in Tai
Po,
There is no air quality monitoring station
(AQMS) operated by EPD in the vicinity.
The nearest EPD’s AQMS is located at the
rooftop of Tai Po Government
Table 4.2 Background
Air Quality
|
Air Pollutant |
Background Air Quality
(µg m-3) (a) |
|
Total Suspended Particulates (TSP) |
67 |
|
Respirable Suspended Particulates (RSP) |
49 |
|
Nitrogen Dioxide (NO2) |
51 |
|
|
14 |
|
Carbon Monoxide (CO) |
719 (b) |
|
Notes: (a)
Annual
average data on air pollutant concentrations measured at the EPD Tai Po AQMS
recorded in 2006 -2010 (http://www.epd-asg.gov.hk/english/report/aqr.php). (b)
Since
no CO data is recorded at EPD Tai Po AQMS, therefore, the CO data recorded at
Tap Mun AQMS is used. |
|
Table 4.3 and Figure 4.1 show the
identified air sensitive receivers (ASRs) or those buildings that may be
affected. ASRs were identified in line
with the requirements set out in the Appendix
C of EIA Study Brief (ESB-206/2009) and Annex 12 of the EIAO-TM and with reference to the latest
Outline Zoning Plan (OZP) (No. S/TP/23 gazetted in August 2011).
Table 4.3 Identified
Air Sensitive Receivers
|
ASR |
Description |
Uses |
Maximum Height |
Approximate Distance from
SLT Project Boundary or Sha Lo |
|
A1 |
Fung Yuen Lo Tsuen |
Residential |
10 |
260 |
|
A2 |
Mak |
Residential |
10 |
190 |
|
A3 |
Fung Yuen |
Residential |
10 |
175 |
|
A4 |
Tin Sam |
Residential |
10 |
125 |
|
A5 |
Ha Hang |
Residential |
10 |
125 |
|
A6 |
Cheung Uk |
Residential |
10 |
200 |
|
A7 |
Lei |
Residential |
10 |
380 |
|
A8 |
Tai |
Recreational |
- |
65 |
4.5
Air Quality Impact Assessment
4.5.1
Ecological Reserve
Enhancement
and Other Works
The enhancement works will include installation of a
drop bar at the road entrance to Sha Lo Tung Valley, weed and rubbish removal,
enhancement planting, wet farmland and marsh restoration, plantation, trail
maintenance, provision of signage. In
addition, the existing damaged footpaths alongside the natural streams will be
maintained and enhanced manually (natural stones but not concrete will be
used). This work will be carried out
with hand tools only. No major
excavation works will be required and no dust impact is anticipated.
In accordance with Section 3.3.3, the other works within
the Ecological Reserve will include minor improvement to the existing footpath
to Lei Uk, construction and removal of a temporary
footbridge and provision of fence around broken village houses and structures at Lei Uk. All of
the works will be undertaken by hand tools and will be completed within
3 months.
No powered mechanical equipment (PME) will be used.
Lei
A temporary footbridge will be constructed
across the stream within the Sha Lo Tung Stream SSSI (please refer to Section 3.2.3 for detail). Minor excavation for the construction of
bridge footing is required. It is
estimated that about 1.1 m3 of C&D materials will be generated
from the footing construction. About 0.4
m3 of this material will be reused as backfilling onsite and the
rest will be disposed offsite. The temporary footbridge will be removed
manually after the erection of fencing around Lei Uk. All of the works would be implemented using
hand tools. In view of the small
quantity of C&DM to be generated, no significant dust impact is anticipated.
Minor improvement of the existing new footpath to Lei
Uk such as vegetation removal in certain section of
the footpath may be required but no dust impact is anticipated.
Maintenance
and Operation
Only minor works will be required during emergencies
or routine maintenance of the Ecological Reserve. No air pollution generating activity is
required and no air quality impact is expected during the operational phase.
4.5.2
Development Site
Construction
Phase
Potential dust impact to the vicinity is one of the
air quality issues during the construction of the proposed Nature
Interpretation Centre, Multi-Cultural Education Retreat and Columbarium. The area of the Development Site is
approximately 4.1 hectares. The
construction works (including site formation and superstructure works) for the
Development Site are expected to last for 17 months in total. The site formation works will be carried out
in three stages. The detailed site formation
works in each stage have been described in Section
3. The site formation works for
Stages 1, 2 and 3 will last for 6 months, 5 months and 6 months,
respectively. The major construction
works will include site clearance, site formation, slope stabilization works,
building and civil construction and landscaping works. Materials handling, excavation and filling,
stockpiling, wind erosion and truck movements during site formation works will
likely be the major dust generating activities.
A total of 16,100 m3 of soil will be excavated from site
formation works including 3,600 m3 in Stage 1, 11,300 m3
in Stage 2 and 1,200 m3 in Stage 3.
Filling work is required to level the ground in which a total of 7,600 m3
of soil will be required. The scale of
the construction works is likely to be small and the rate of excavated soil generation
will also be low (ie about maximum average of 134 m3
per day ([1])).
The nearest ASR to the worksite, Fung Yuen Lo Tsuen (ASR A1), is located about 770 m away the
construction worksite boundary. With the
implementation of recommended site practices and dust control measures
stipulated in the Air Pollution Control
(Construction Dust) Regulation and considering large separation distance
between worksite and the nearest ASR, the dust impact at ASRs is expected to be
low and no adverse dust impact is anticipated.
Nitrogen dioxide (NO2) and
sulphur dioxide (SO2) will be emitted from diesel-powered
construction equipment. However, the number
of such equipment to be operated will be limited owing to the small size of the
works areas, emissions from the equipment are expected to be minor, and no
adverse air quality impact is anticipated.
Operational
Phase
Vehicular emissions from
Burning of effigies and paper offerings in the
Development Site (including the columbarium, multi-cultural education retreat
and open space) will not be allowed, and therefore no adverse impact to air
quality is anticipated.
Especially during public holidays and festival
holidays, the maximum number of visitors accumulated within a 2-hour period
will be 2,500 visitors at any one time.
However, as discussed above, the development does not allow burning of
effigies and paper offerings, therefore, adverse air quality impact during such
period will not be anticipated.
In addition, the Motor
Vehicle Idling (Fixed Penalty) Ordinance has been in effect on 15 December 2011. It is prohibited to allow the drivers leaving
vehicle engines idling for more than three minutes in any 60-minute
period. As such, no air emission is
anticipated from the shuttle buses during idling in the parking area.
4.5.3
Road Improvement Works
Construction
Phase
The existing
A total of 11,000 m3 of soil
will be excavated in three phases over the 19-month construction period. With 24 working days a month, about 20 m3
of soil will be generated per day (refer to Section
8). Even if a peak factor of 2 is
applied to cater for the potential increase in spoil generation during the
overlapping of two phases, the estimated peak volume of spoil to be generated
per day (ie 40 m3) is still considered
small. The road improvement works will
be carried out in phases, and therefore the works area will be small. The nearest ASR, Ha Hang, is located at about
125 m from the nearest site boundary.
During the improvement work, dust control measures stipulated in the Air Pollution Control (Construction Dust)
Regulation will be implemented. With
the consideration of small works area, limited volume of spoil generated during
excavation and implementation of dust control measures, dust generated from the
construction works at any one time is expected to be limited and the dust
impact is insignificant.
Nitrogen dioxide (NO2) and sulphur
dioxide (SO2) will be emitted from diesel-powered construction
equipment. The number of such equipment
to be operated will be limited owing to the small size of the works area. Air emissions from construction equipment are
expected to be minor and no adverse air quality impact is anticipated.
Operational
Phase
Vehicular emissions are the only air quality concern
during the operation of the widened
4.5.4
Cumulative Impacts
Construction
Phase
According to the construction programme, the
construction works of ecological reserves, development site and road
improvement would not cause cumulative dust impact.
No other concurrent projects were also identified in
the vicinity to cause cumulative dust impact.
Operational
Phase
No cumulative impact is anticipated.
4.6.1
Ecological Reserve
Enhancement
Works
Since hand tools are used, no significant dust impact
is anticipated during construction phase and no mitigation measures will be
required.
Maintenance
and Operation
No mitigation measures will be required as no air
pollution will be generated during the maintenance and operation.
4.6.2
Development Site
Construction
Phase
The following dust control measures are recommended
to be implemented:
·
A
vehicle washing facility should be provided at the main exit of the
construction site and water recaptured or discharged offsite via sand traps to
the drainage paths away from the SSSI;
·
Excavated
spoils should be covered or wetted, especially during the dry season;
·
Exposed
surfaces should be sprayed with water or covered entirely to avoid fugitive
dust emissions;
·
Areas
where dusty work takes place should be sprayed with water immediately prior to,
during and immediately after dusty activities so as to maintain the entire
surface wet;
·
Temporary
stockpiles of dusty materials, if any, should be covered entirely or sprayed with
water;
·
During
transportation by truck, materials should not be loaded to a level higher than
the side and tail boards, and should be dampened or covered before leaving the
site;
·
Dusty
loads transported by the trucks should be covered entirely to avoid any
spillage onto public roads;
·
During
air flushing for soil nail drilling, dust screens should be provided at the
three sides of the drilling machine and the soil nailing area to avoid fugitive
dust emissions; and
·
Diesel-powered
equipment should be properly maintained to avoid black smoke emissions.
Operational
Phase
Since the ASRs are located well away from
4.6.3
Sha Lo
Construction
Phase
The following dust control measures are recommended
to be implemented during the road improvement works.
·
Excavated
spoils should be covered or wetted, especially during the dry season;
·
Exposed
surfaces should be kept wet always or entirely covered to avoid fugitive dust
emissions;
·
During
transportation by truck, materials should not be loaded to a level higher than the
side and tail boards, and should be dampened or covered before leaving the
site;
·
Dusty
loads transported by the trucks should be covered entirely to avoid any
spillage onto public roads;
·
During
air flushing for soil nail drilling, dust screens should be provided at the
three sides of the drilling machine and the soil nailing area to avoid fugitive
dust emissions; and
·
Diesel-powered
equipment should be properly maintained to avoid black smoke emissions.
Operational
Phase
Since the buffer distances between the ASRs and the
widened
4.7.1
Ecological Reserve
No residual impacts are anticipated during both
construction and operational phases.
4.7.2
Development Site
No residual impacts are anticipated during both
construction and operational phases.
4.7.3
Road Improvement Works
No residual impacts are anticipated during both
construction and operational phases.
4.8
Environmental Monitoring and Audit Requirements
4.8.1
Ecological Reserve
No specific air quality monitoring and audit programme
is required as no air pollution is predicted to be generated during both
enhancement works and maintenance and operation stages. Regular site audit will be performed to
ensure no dust impact is generated.
4.8.2
Development Site
During the construction phase, regular environmental
site audit is required to ensure the implementation of dust control
measures. No EM&A programme is
required during operational phase.
4.8.3
Sha Lo
During the construction phase, regular environmental
site audit is required to ensure the implementation of dust control
measures. No EM&A programme is
required during operational phase.
4.9.1
Ecological Reserve
The enhancement works will include the installation of
drop bar at the road entrance to Sha Lo Tung Valley, weed and rubbish removal,
enhancement planting, wet farmland and marsh restoration, plantation, trail
enhancement, provision of signage and enhancing the existing damaged footpaths
alongside the natural streams. These
works will be carried out with hand tools only.
No major excavation works will be required and no dust impact is
anticipated.
Only minor works will be required during emergencies
or routine maintenance. No air pollution
generating activity is required and no air quality impact is expected during
the operational phase.
4.9.2
Development Site
The construction works at the Development
Site will be carried out in three stages.
Dust nuisance from construction works and gaseous emissions from diesel-powered
equipment are the potential air quality concerns during the construction of the
Multi-Cultural Education Retreat cum Columbarium. Dust may be generated from materials
handling, excavation and filling, wind erosion and truck movements during site
formation works. The scale of the
construction works is likely to be small and the rate of excavated soil
generation will also be low (ie 94 m3/day
on average). With the implementation of
recommended dust control measures and good site practices, dust impact is not
expected. The number of diesel-powered
construction equipment to be operated at any one time will be limited owing to
the small scale of the works and the division of the works into phases. Gaseous emissions from the operation of
diesel-powered equipment are expected to be minor, and no adverse air quality
impact is anticipated.
The number of visitors during public holidays and
festival holidays will be increased.
However, burning of effigies and paper offerings will not be allowed at
the future development; therefore no adverse air quality impact is anticipated
during the operation of the development.
In-house management measures such as signage to remind visitors on the
prohibition of burning effigy should be provided.
Vehicular emissions from
In addition, the Motor
Vehicle Idling (Fixed Penalty) Ordinance has been in effect on 15 December 2011. It is prohibited to allow the drivers leaving
vehicle engines idling for more than three minutes in any 60-minute
period. As such, no air emission is
anticipated from the shuttle buses during idling in the parking area.
4.9.3
Road Improvement Works
Dust nuisance from construction works and gaseous
emissions from diesel-powered equipment are the potential concerns during the
road improvement works. Materials
handling, wind erosion and truck movements are expected to be the major sources
of construction dust. The road
improvement works will be conducted over a period of 19 months and the works
will be carried out in phases, each of which covers only a road section of
approximately 800m in length, and therefore the works area will be small. In view of the large separation distances
between ASRs and the works area, no adverse dust impact is anticipated. The number of diesel-powered equipment to be
used for the works will be limited owing to the small size of the works
area. The air emissions from diesel
equipment are expected to be minor and no adverse air quality impact is
expected. With the implementation of the
recommended dust control measures and good site practices, the dust impact is
expected to comply with the dust criteria.
Vehicular emissions are envisaged to be the only air
quality concern during the operation of the widened