3.1.1.1
This
section presents the assessment on potential air quality impacts arising from
construction and operation of the Project, which has been conducted in
accordance with the criteria and guidelines as stated in Section 1 of Annex 4
and Annex 12 of the Technical Memorandum on Environmental Impact Assessment
Process (EIAO-TM) as well as the requirements given in Clause 3.4.4 and
Appendix B of the EIA Study Brief (No. ESB-320/2019).
·
Air Pollution Control Ordinance (APCO) (Cap. 311) - this provides the power for controlling air
pollutants from a variety of stationary and mobile sources and encompasses a
number of Air Quality Objectives (AQOs);
·
Air
Pollution Control (Construction Dust) Regulation;
·
Air
Pollution Control (Non-road Mobile Machinery)
(Emission) Regulation;
·
Air
Pollution Control (Fuel Restriction) Regulation; and
·
Environmental
Impact Assessment Ordinance (EIAO) (Cap. 499), EIAO-TM, Annex 4 and Annex 12.
Air Quality Objectives
3.2.1.2 The new set of AQOs which came into
effect on 1 January 2022, is tabulated in Table 3.1.
Table 3.1 New Hong Kong Air Quality
Objectives
|
Pollutant
|
Averaging Time
|
Concentration Limit, µg/m3 [1]
|
No. of Exceedances Allowed per Year
|
|
Fine Suspended
Particulates
(PM2.5 / FSP) [3]
|
24-hour
|
50
|
18 [5]
|
|
Annual [2]
|
25
|
Not applicable
|
|
Respirable Suspended
Particulates (PM10 / RSP) [4]
|
24-hour
|
100
|
9
|
|
Annual [2]
|
50
|
Not applicable
|
|
Sulphur Dioxide (SO2)
|
10-minute
|
500
|
3
|
|
24-hour
|
50
|
3
|
|
Nitrogen Dioxide (NO2)
|
1-hour
|
200
|
18
|
|
Annual [2]
|
40
|
Not applicable
|
|
Photochemical Oxidants
[as Ozone (O3)]
|
8-hour
|
160
|
9
|
|
Carbon Monoxide (CO)
|
1-hour
|
30,000
|
0
|
|
8-hour
|
10,000
|
0
|
|
Lead (Pb)
|
Annual [2]
|
0.5
|
Not applicable
|
Notes:
[1] All measurements of the concentration of
gaseous air pollutants, i.e., sulphur
dioxide, nitrogen dioxide, ozone and carbon monoxide, are to be adjusted to a
reference temperature of 293 Kelvin and a reference pressure of 101.325
kilopascal.
[2] Arithmetic
mean.
[3] “Fine suspended particulates” means suspended
particles in air with a nominal aerodynamic diameter of 2.5 µm or less.
[4] “Respirable suspended particulates” means
suspended particles in air with a nominal aerodynamic diameter of 10 µm or
less.
[5] Under
the new AQOs, the number of exceedances allowed per year for daily FSP is 35
times. However, for new government
projects, the number of exceedances allowed per year for daily FSP is 18 times
only.
Air Pollution Control
(Construction Dust) Regulation
3.2.1.3
With
reference to the Air Pollution Control (Construction Dust) Regulation,
it specifies processes that require special dust control. The Contractors are required to inform the
EPD and adopt proper dust suppression measures while carrying out “Notifiable
Works” (which requires prior notification by the Regulation) and
“Regulatory Works” to meet the requirements as defined under the Regulation.
Air Pollution Control (Non-road Mobile
Machinery) (Emission) Regulation
3.2.1.4
The
Air Pollution Control (Non-road Mobile Machinery)
(Emission) Regulation comes into operation on 1 June 2015. Under the Regulation, non-road mobile
machinery (NRMMs), except those exempted, are required to comply with the
prescribed emission standards. From 1
September 2015, all regulated machines sold or leased for use in Hong Kong must
be approved or exempted with a proper label in a prescribed format issued by
EPD. Starting from 1 December 2015, only
approved or exempted NRMMs with a proper label are allowed to be used in
specified activities and locations including construction sites. The Contractor is required to ensure the
adopted machines or non-road vehicle under the Project could meet the
prescribed emission standards and requirement.
Air Pollution Control (Fuel Restriction) Regulation
3.2.1.5
Air Pollution Control (Fuel Restriction) Regulations should also be complied with an aim
to prohibit the use of high sulphur content solid and liquid fuel for
commercial and industrial appliances.
The Project site is located within the “Sha Tin Fuel Restriction Area”
under the Air Pollution Control (Fuel
Restriction) Regulations. Except
for construction site or during emergency, only gaseous fuel is allowed to be
used in the Sha Tin Fuel Restriction Area.
For any fuel-using equipment that is used or operated in construction
site or during emergency in Sha Tin Fuel Restriction Area, Ultra Low Sulphur
Diesel (ULSD) is practically the liquid fuel to be used.
EIAO-TM
3.2.1.6
Annex
4 of EIAO-TM stipulates that hourly Total Suspended Particulate (TSP)
level should not exceed 500µg/m³ measured at 298 K and 101.325 kPa (one
atmosphere) for the construction dust impact assessment. It also stipulates that the odour level at
air sensitive receiver should meet 5 odour units based on an averaging time of
5 seconds for odour prediction assessment.
3.2.1.7
Guidelines for conducting air quality
assessment are stipulated in Annex 12 of EIAO-TM, including the determination
of air sensitive receivers (ASRs), the assessment methodology, baseline study
and impact prediction and assessment.
3.3.1.2
The
Project site covers the existing TWN, which is approximately 2 kilometres (km)
long and 40 metres (m) wide, located at the centre of Tai Wai District and is
mainly surrounded by residential developments as illustrated in Figure 3.1.
3.3.1.3
The
dominant existing air emission source within 500m assessment area from the
Project area is vehicular emission from Shing Mun Tunnel Road, Tai Po Road (Tai
Wai), Tsing Sha Highway, Mei Tin Road, Heung Fan Liu Street and Pik Tin Street, as well as emission from Fu Shan
Crematorium. Within the 500m assessment area,
four chimneys were identified
from Fu Shan Crematorium at the time of the assessment. As the emission from Fu Shan Crematorium is
controlled under the specified process (SP) licence, no adverse air quality
impact arising from this SP is anticipated.
3.3.1.4
The
nearest EPD general air quality monitoring station to the Project area is
situated at Sha Tin Government Secondary School. The recent 5-year (between 2016 and 2020)
concentrations of air pollutants measured at the monitoring station relevant to
the Project, including Fine Suspended Particulates (FSP), Respirable Suspended
Particulates (RSP), Sulphur Dioxide (SO2) and Nitrogen Dioxide (NO2),
were extracted and are summarised in Table 3.2.
It is observed that the maximum 24-hour average FSP concentrations and
the 10th highest 24-hour average FSP concentrations in the latest 5
years complied with the prevailing AQO.
For RSP, non-compliance of the maximum 24-hour average concentrations
were noted in Year 2016 to Year 2018 but the 10th highest values in
Years 2016 to 2020 all complied with the prevailing AQO. Both annual average FSP and RSP
concentrations, 10-minutes and 24-hour average SO2, hourly and
annual average NO2 complied with prevailing AQOs. In general, the results showed that there was
a decreasing trend in the pollutants levels in the past 5 years.
Table 3.2 Average Concentrations of Pollutants in
the Recent Five Years (Year 2016 – 2020) at Sha Tin EPD Air Quality Monitoring
Station
|
Pollutant
|
Averaging Time
|
Previous
AQO [1]
|
Data Summary
|
Year [2]
|
|
2016
|
2017
|
2018
|
2019
|
2020
|
|
Fine
Suspended Particulates (FSP)
|
24-hr
|
75 (9)
|
Max.
|
62
|
90
|
70
|
64
|
56
|
|
10th
Max.
|
44
|
54
|
40
|
39
|
32
|
|
No.
of Exceedance(s)
|
0
|
1
|
0
|
0
|
0
|
|
Annual
|
35
|
-
|
20
|
21
|
19
|
17
|
15
|
|
Respirable
Suspended Particulates (RSP)
|
24-hr
|
100 (9)
|
Max.
|
102
|
103
|
102
|
97
|
71
|
|
10th
Max.
|
66
|
72
|
65
|
60
|
54
|
|
No.
of Exceedance(s)
|
2
|
1
|
1
|
0
|
0
|
|
Annual
|
50
|
-
|
29
|
31
|
32
|
28
|
25
|
|
Sulphur
Dioxide (SO2)
|
10-min
|
500 (3)
|
Max.
|
83
|
73
|
80
|
35
|
36
|
|
4th
Max.
|
67
|
53
|
76
|
27
|
31
|
|
24-hr
|
125 (3)
|
Max.
|
17
|
17
|
20
|
15
|
14
|
|
4th
Max.
|
16
|
16
|
16
|
12
|
13
|
|
No.
of Exceedance(s)
|
0
|
0
|
0
|
0
|
0
|
|
Nitrogen Dioxide (NO2)
|
1-hr
|
200 (18)
|
Max.
|
176
|
178
|
198
|
185
|
183
|
|
19th
Max.
|
137
|
144
|
149
|
150
|
136
|
|
No.
of Exceedance(s)
|
0
|
0
|
0
|
0
|
0
|
|
Annual
|
40
|
-
|
38
|
34
|
35
|
32
|
28
|
Notes:
[1] Previous AQOs, which is put in force
since 1 January 2014, are referenced to evaluate past air quality
conditions. Values in (
) mean the number of exceedances allowed per year.
[2] Bolded values mean exceedance of the
AQOs.
[3] All concentration units are in
microgram per cubic metre (µg/m3).
3.3.1.5
Apart
from the air quality monitoring data, EPD has released a set of background air
quality levels extracted from “Pollutants in the Atmosphere and their Transport
over Hong Kong” (PATH) model (PATH v2.1) in July 2021. The PATH model Year 2025 data of the
assessment area are summarised in Table 3.3 below. The 19th highest 24-hour and
annual average concentrations of FSP would comply with the new AQOs, and all
other pollutants level would also comply with the new AQOs.
Table 3.3 Background Air Pollutants in Year 2025 Extracted from the
PATH Model (PATH v2.1)
|
Pollutant
|
Averaging Time
|
Prevailing AQO
[1]
|
Data Summary
|
PATH-2020 Grid
in Year 2025 [2][5]
|
|
39,39
|
39,40
|
40,39
|
40,40
|
41,39
|
41,40
|
|
Fine Suspended Particulates (FSP) [4]
|
24-hr
|
50 (18)
|
Max.
|
69
|
67
|
70
|
67
|
67
|
68
|
|
19th Max.
|
33
|
34
|
33
|
33
|
32
|
33
|
|
No. of Exceedance(s)
|
7
|
7
|
7
|
7
|
6
|
7
|
|
Annual
|
25
|
-
|
14
|
15
|
14
|
14
|
14
|
14
|
|
Respirable Suspended Particulates (RSP) [3]
|
24-hr
|
100 (9)
|
Max.
|
84
|
83
|
86
|
83
|
83
|
84
|
|
10th Max.
|
62
|
62
|
61
|
62
|
62
|
61
|
|
No. of Exceedance(s)
|
0
|
0
|
0
|
0
|
0
|
0
|
|
Annual
|
50
|
-
|
26
|
27
|
26
|
26
|
26
|
26
|
|
Sulphur Dioxide (SO2)
|
10-min
|
500 (3)
|
Max.
|
54
|
55
|
47
|
55
|
45
|
47
|
|
4th Max.
|
54
|
55
|
47
|
55
|
45
|
47
|
|
No. of Exceedance(s)
|
0
|
0
|
0
|
0
|
0
|
0
|
|
24-hr
|
50 (3)
|
Max.
|
16
|
16
|
15
|
15
|
14
|
15
|
|
4th Max.
|
10
|
10
|
10
|
10
|
10
|
10
|
|
No. of Exceedance(s)
|
0
|
0
|
0
|
0
|
0
|
0
|
|
Nitrogen Dioxide (NO2)
|
1-hr
|
200 (18)
|
Max
|
139
|
140
|
143
|
147
|
144
|
149
|
|
19th Max.
|
96
|
95
|
95
|
89
|
93
|
93
|
|
No. of Exceedance(s)
|
0
|
0
|
0
|
0
|
0
|
0
|
|
Annual
|
40
|
-
|
16
|
15
|
17
|
15
|
17
|
17
|
Notes:
|
[1] New AQOs, which came into effect on
1 January 2022, are referenced to evaluate background air quality
conditions. Values in ( ) mean the number of exceedances allowed per year.
[2] Bolded values mean exceedance
of the AQOs.
[3] Annual FSP concentration is adjusted by
adding 3.5 µg/m3 with reference to Guidelines on Choice of Models
and Model Parameters.
[4] 10th highest daily and annual RSP
concentration is adjusted by adding 11.0 µg/m3 and 10.3 µg/m3
respectively with reference to “Guidelines on Choice of Models and Model
Parameters”.
[5] All
concentration units are in microgram per cubic metre (µg/m3).
|
3.4.1.1 In accordance with Clause 3.4.4.2 of
the EIA Study Brief, the assessment area is defined by a distance of 500m from
the boundary of the Project boundary as illustrated in Figure 3.1.
3.4.1.2
For
identification of the representative ASRs within the assessment area that would
likely be affected by the potential impacts from the Project, a review has been
conducted based on relevant available information including topographic maps,
Outline Zoning Plans (OZPs) (such as the
Approved Shatin OZP No. S/ST/36) and other published plans in the vicinity of the
Project site. The representative ASRs
are identified and summarised in Table 3.4.
Table 3.4 Representative Air
Sensitive Receivers
|
ASR
|
Description
|
Land
Use
|
No.
of Storeys
|
Approximate Horizontal Distance from the
Nearest Site Boundary (m)
|
|
Existing Air Sensitive
Receivers
|
|
A1
|
Temporary Accommodations
|
Residential
|
2
|
5
|
|
A2
|
Heung Fan Liu New Village
|
Residential
|
3
|
47
|
|
A3
|
Mei Tin Estate
|
Residential
|
40
|
21
|
|
A4
|
Granville Garden
|
Residential
|
28
|
15
|
|
A5
|
Mei Ying Court
|
Residential
|
27
|
16
|
|
A6
|
Park View Garden
|
Residential
|
27
|
27
|
|
A7
|
Tai Wai New Village
|
Residential
|
3
|
148
|
|
A8
|
Pui Kiu College
|
Educational
Institution
|
7
|
235
|
|
A9
|
Mei Pak Court
|
Residential
|
32
|
20
|
|
A10
|
May Shing Court
|
Residential
|
35
|
11
|
|
A11
|
Mei Lam Commercial Centre
|
Shopping
centre
|
3
|
6
|
|
A12
|
Peak One
|
Residential
|
6-15
|
164
|
|
A13
|
Peak House
|
Residential
|
3
|
58
|
|
A14
|
Village Houses at Tung Lo Wan Hill Road
|
Residential
|
3
|
172
|
|
A15
|
TWGHs Tsoi Wing Sing Primary School
|
Educational
Institution
|
7
|
13
|
|
A16
|
Buddhist Wong Wan Tin College
|
Educational
Institution
|
6
|
30
|
|
A17
|
The Great Hill
|
Residential
|
11
|
145
|
|
A18
|
Tung Lo Wan Village
|
Residential
|
3
|
96
|
|
A19
|
Low-rise Residential Developments at Tai Wai
|
Residential
|
3-5
|
14
|
|
A20
|
TWGHs Sin Chu Wan Primary School
|
Educational
Institution
|
7
|
20
|
|
A21
|
Tai Wai Soccer Pitch
|
Recreational
|
-
|
15
|
|
A22
|
Industrial Buildings at Tai Wai
|
Industrial
|
7-11
|
16
|
|
A23
|
Tai Wai Playground
|
Recreational
|
-
|
11
|
|
A24
|
Man Lai Court
|
Residential
|
20
|
5
|
|
A25
|
Caritas Lok Jun School
|
Educational
Institution
|
5
|
80
|
|
A26
|
Sha Tin (Tai Wai)
Clinic
|
Clinic
|
2
|
320
|
|
A27
|
Ng Yuk Secondary School
|
Educational
Institution
|
7
|
132
|
|
A28
|
San Tin Wai
|
Residential
|
3
|
157
|
|
A29
|
Che Kung Temple
|
Place of
Public Worship
|
2
|
60
|
|
A30
|
Koon Ngam Ching Yuen
|
Place of
Public Worship
|
1
|
166
|
|
Planned Air Sensitive
Receivers
|
|
AP1
|
Planned Comprehensive Development Area Next to
Tai Wai Station
|
Residential
|
-
|
44
|
|
AP2
|
Joint-user Complex at Tsuen Nam Road, Tai Wai
|
Residential
and institutional uses
|
-
|
11
|
3.5.1.1
The
construction of the Project would commence in Q1 2024 and complete by Q4
2029. Referring to the tentative
construction programme in Appendix 2.2 and general layout plan in Figure 2.2, the Project site would be divided
into six work sections for construction, Section 1 to Section 6. The locations of the six work sections are
indicated in Figure 3.1. The main construction tasks of the Project
include:
A.
Channel
bed modification for Section 1 to 6;
B.
Improvement
of existing walkways such as construction of viewing deck/pavilion, renovation
of existing footbridges for Section 1 to 5 and demolition of existing
footbridge in Sections 3 and 5, as well as improvement of riparian public open
spaces (including construction of riparian walkway, water play features and UV
Disinfection System, and visitor facilities) in Sections 2 to 4;
C.
Construction
of dry weather flow interceptor (DWFI) system along the nullah and associated
connection works to existing sewerage system for Section 1 (from north of Tsuen
Nam Road near Tai Wai Soccer Pitch) to 5 & underground pumping facilities
(including underground water pumps, water pipes, wet well and valve chamber) in
Section 3 and underground water pipes (mainly housed within the DWFI system and
to be constructed alongside construction of DWFI system) for Sections 3 to 6
for ecological enhancement associated water retention and supplement
D.
Landscape
works along the bankside of nullah and utility works
for Section 1 to 5
E.
Desilting
at downstream tidal zone for Section 1
3.5.1.2 The construction works will be carried out section by section, from the downstream to upstream of
each work section. Desilting works at
downstream tidal zone would be conducted at the commencement and prior to the
completion of the construction works to remove the
silting accumulated at the nullah.
Based on the preliminary engineering design, the
maximum size of the active construction works area at any one time would not be
longer than 100m along the nullah at each work area.
3.5.1.3
Construction
dust is the major concern during construction of the Project. Fugitive dust generated from various
construction activities, including excavation, demolition of existing
footbridge, backfilling, and wind erosion of the excavated areas and
stockpiles, would be major dusty activities which would impose potential dust
impact on the air sensitive receivers in the vicinity.
3.5.1.4
The
operation of powered mechanical equipment (PMEs) within the construction area
and the construction vehicles for the transportation of materials would
contribute to the gaseous emissions to the surrounding air.
3.5.1.5
Potential
odour emission may be generated during the desilting works at downstream tidal
zone/excavation of nullah bed and the transfer and disposal of
desilted/excavated materials.
3.5.2.1
The
purpose of the Project is to revitalise the existing concrete-lined
TWN into a green space to connect the community with nature. The beautification and vegetating of the
existing nullah would bring positive influence on the surrounding
environment. In view of the Project
nature, adverse air quality impact due to the operation of the Project is not
anticipated. With the implementation of
DWFI system under the Project and treatment wetlands, the existing dry weather
flows from drainage outlets along TWN would either be intercepted and diverted
to the existing sewerage system for conveying to Shatin Sewage
Treatment Works for treatment by the DWFI system, or be discharged into the
treatment wetlands installed at drainage outlets for in-situ polishing. Furthermore, with the
modification of channel bed downstream of TWN’s low flow channel near its
confluence with Shing Mun River near Man Lai Court, the excessive accumulation
of silt brought by tidal influence due to the flat and uneven nullah bed in
front of the broad-crested weir would be greatly reduced. With the abovementioned designs, it is
expected that the odour
nuisance of TWN would be alleviated due to the operation of the Project.
3.6
Prediction
and Evaluation of Environmental Impacts
3.6.1
Construction Phase
Fugitive Dust
3.6.1.1 The Project will be constructed in
sections by sections. The construction
works at the nullah will be divided into six sections and the construction
activities will not be undertaken at the entire work site at the same
time. The construction tasks for each
work section would be completed before commencement of the similar construction
tasks at another work section. As
mentioned in Section 3.5.1.2, the maximum size of the active construction work area at any one time
would not be longer than 100m along the nullah at each work area. Hence, the active exposed work site would be
limited.
3.6.1.2 Various construction activities,
including excavation, backfilling, material handling and wind erosion of the
excavated areas and stockpiles would be the main sources of fugitive dust. The production of concrete would be conducted
with the use of a concrete lorry mixer, therefore,
adverse dust impact is not anticipated.
3.6.1.3 Referring to construction programme
in Appendix 2.2, the construction duration at each
work section is summarised in Table 3.5.
The dusty works including the
excavation works for the nullah bed per work section and demolition of two
existing footbridges in Sections 3 and 5 would each only last for 1 month.
Table 3.5 Construction Duration at Each Work Section
|
ID
|
Main Construction Tasks
|
Main Construction Elements
|
Construction Duration at Work Section (month)
|
|
1
|
2
|
3
|
4
|
5
|
6
|
|
A-1
|
Channel Bed Modification
|
Excavation
|
1
|
1
|
1
|
1
|
1
|
1
|
|
A-2
|
Re-surfacing
and Greening of the Nullah
|
3
|
5
|
5
|
5
|
5
|
5
|
|
A-3
|
Construction
of Energy Dissipation Structures at Upstream Section
|
-
|
-
|
-
|
-
|
-
|
2
|
|
B-1
|
Improvement
of Existing Walkways and Riparian Public Open Spaces
|
Construction
of Viewing Deck / Pavilion / Footbridges
|
1
|
3
|
3
|
3
|
3
|
-
|
|
B-2
|
Construction
of Staircases and Ramps
|
2
|
3
|
3
|
3
|
3
|
-
|
|
B-3
|
Construction
of UV Disinfection System, Water Play Features, Toilet, and Management Office
|
-
|
3
|
3
|
3
|
-
|
-
|
|
B-4
|
Demolition
of Existing Footbridge
|
-
|
-
|
1
|
-
|
1
|
-
|
|
C-1
|
Construction
of Dry Weather Flow Interceptor & Recirculation Pumping Facilities
|
Connection
Work to the Existing Sewerage System
|
2
|
-
|
-
|
-
|
-
|
-
|
|
C-2
|
Construction
of Dry Weather Flow Intercepting Channel and Pipe Laying along the Nullah
|
3
|
5
|
5
|
5
|
5
|
5
|
|
C-3
|
Pumping
Facilities & associated E&M Works
|
-
|
-
|
3
|
-
|
-
|
-
|
|
D-1
|
Landscaping
and Miscellaneous
|
Landscaping
/ Greening of the Bankside along the Nullah
|
1
|
7
|
7
|
7
|
7
|
-
|
|
D-2
|
Utility
Works
|
2
|
5
|
5
|
5
|
5
|
-
|
|
E-1
|
Desilting
|
Desilting
at Downstream Tidal Zone
|
5
|
-
|
-
|
-
|
-
|
-
|
3.6.1.4 Due to the small amount of C&D
materials to be disposed of off-site, the dust generated from construction
vehicles for materials handling would generally be limited within the work
areas. In accordance with the
preliminary engineering information, for the inert C&D materials, it is
proposed to dispose at Tseung Kwan O Area 137 Fill Bank for beneficial reuse in
other projects via Lung Cheung Road and Kwun Tong Road or other approved
PFRF. It is estimated that an average of
about 1 truck trip per day would be required to dispose these materials off-site. For non-inert C&D materials, it is
planned to deliver to NENT
landfill via Tate's Cairn Highway, Territories Circular Road and Po Shek Wu Road or other approved landfills. It is estimated that an average of about 1
truck trip per day would be required.
Considering the limited number of dump truck in operation together with
tarpaulin covering of these dump trucks and washing the vehicle wheel and body
before leaving the construction site, dust nuisance during transportation of
the C&D materials would not be anticipated.
3.6.1.5 Given that the construction works of
the Project would be of small-scale and confined in a smaller work area, small
influence zone would be expected. With
proper and effective implementation of good site practices and mitigation
measures stipulated in the Air Pollution Control (Construction Dust)
Regulation, dust emission from the construction works would be well controlled
and minimised. No adverse construction
dust impacts from the Project would therefore be anticipated.
Operation
of PMEs
3.6.1.6 The fuel combustion from the use of
PMEs during construction works could be a potential source of air pollutants
such as PM, NO2, SO2 and CO. To improve air quality, Air Pollution Control
(Fuel Restriction) Regulation and Air Pollution control (Non-road
Mobile Machinery) (Emission) Regulation are introduced to regulate SO2 emissions
from commercial and industrial processes, and emissions from machines and
non-road vehicles respectively. In addition,
all construction plants are required to use ultra-low-sulphur diesel (ULSD)
(defined as diesel fuel containing not more than 0.005% sulphur by weight) as
stipulated in Environment, Transport and Works Bureau Technical Circular
(ETWB-TC(W)) No. 19/2005 on Environmental Management on Construction
Sites.
3.6.1.7 The number and type of PMEs to be
used on site for each main construction task under Sections 1 to 6 are
presented in Appendix 4.6.
According to the preliminary engineering design, while there would be
several sub-group construction works under each main
construction task, the construction periods of these sub-group works would not
be overlapped. Therefore, the PMEs of
each sub-group works/construction sequence would not be operated
concurrently. Based on the construction
programme presented in Appendix 2.2 and the plant inventory attached in
Appendix 4.6, there would be up to 4 concurrent
construction tasks within 500m assessment for all work section - i.e.
“Construction of Viewing Deck / Pavilion, Renovation of Existing Footbridges”
(Group B-1), “Construction of Staircases and Ramps” (Group B-2) “Landscaping / Greening
of the Bankside along the Nullah” (Group D-1) and “Utility Works” (Group D-2)
for Sections 2 to 5 (limited to one month at each section), as well as
“Construction of Staircases and Ramps” (Group B-2), “Pumping Facilities &
associated E&M Works (Group C-3), “Landscaping / Greening of the Bankside
along the Nullah” (Group D-1) and “Utility Works” (Group D-2) for Section 3
(limited to two months). There would be
at most a total of 13 nos. NRMM in operation during the concurrent tasks. As the works are
divided into small sections, the potential air quality impacts would be limited. With proper and effective implementation of
the good practices as stated in the regulations, no significant dust and
gaseous emission impacts from the use of PME would be anticipated.
Odour
3.6.1.8 Desilting works at downstream tidal
zone would tentatively be undertaken at the
commencement and prior to the completion of the construction works respectively
to remove the accumulated silting and debris at the nullah. Each desilting works
at downstream tidal would last for two months and is estimated to produce about
1,000m3 of desilted materials. Potential odour nuisance would be expected
during desilting works. However, the
desilted materials will be contained in watertight container on-site
immediately and be transported off-site by trucks for disposal of at strategic
landfill within one day. Therefore, the
odour emissions are likely to be minimal and localised at a short duration.
3.6.1.10
The
desilted materials and excavated materials from the nullah bed would be
enclosed during trucking, therefore, very minor odour nuisance would be
expected during transportation of these materials for disposal.
Cumulative impacts
from concurrent projects
3.6.1.11 As presented in Section 2.8, there are three concurrent
projects which would potentially overlap with the construction of the Project
is identified within the 500m assessment area, including (i)
planned box culverts in Chui Tin Street under Drainage Improvement Works in Sha Tin and Sai Kung, (ii) Revised Trunk
Road T4 and (iii) Joint-user complex at Tsuen Nam Road,
Tai Wai. Based on the construction
programme of the Project, the cumulative impacts from these concurrent projects
have been considered.
3.6.1.12 The footprint of the planned box
culverts in Chui Tin Street under “Drainage Improvement Works in Sha Tin and
Sai Kung”, which is scheduled to construct in 2023-2031, would partly overlap
with the Project in the eastern end of the Project site at Shing Mun River
Channel. Consider the comparatively small scale of
the planned box culvert and site constraints of this concurrent project (e.g.
works along and across existing carriageways), it is anticipated that the box
culvert would need to be constructed in small sections and there would unlikely
be extensive excavation works that its environmental impacts would be
localised. Likewise, consider the
small and confined scale of the works area of the construction works of this
Project, the construction dust impact is expected to be limited and well
controlled with proper and effective implementation of good site practices and
mitigation measures stipulated in the Air Pollution Control (Construction Dust)
Regulation. Nonetheless, during the
detailed design stage, the contractor of this Project should be requested to
closely liaise the contractors of this potential concurrent project in planning the interfacing works properly to avoid /minimise
repeated and concurrent heavy construction works. With such arrangement in place, cumulative
construction environmental impacts could be further minimised
and no adverse cumulative dust impact would be anticipated.
3.6.1.14 For the “Joint-user complex at Tsuen
Nam Road, Tai Wai”, it is to build a joint-user complex at the existing site of
the Tai Wai Playground at Tsuen Nam Road, Tai Wai to provide community
facilities and public housing. The
construction works are expected to commence in 2024 for completion in 2030 at
the earliest but no detailed construction programme of the project is available
at time of the preparation of this EIA Report.
Consider the small and confined scale of the works area of the
construction works of this Project, the construction dust impact is expected to
be limited and well controlled with proper and effective implementation of good
site practices and mitigation measures stipulated in the Air Pollution Control
(Construction Dust) Regulation. During
the detailed design stage, the contractor of this Project should be requested
to closely liaise the contractors of this potential concurrent project in
planning the interfacing works properly to minimise the potential cumulative
impacts by avoiding/minimising repeated and concurrent heavy construction
works.
3.6.2
Operational Phase
3.6.2.1
As
mentioned in Section 3.5.2.2, similar to the existing practices by the DSD, regular maintenance
works for the drainage and sewerage systems along TWN, including maintenance
desilting at the nullah and minor maintenance to the DWFI system, to remove
excessive silts, debris and obstruction to safeguard the hydraulic capacity of
the nullah would be required. Maintenance desilting of the nullah
should be carried out on an annual basis during dry season (November to
March) when the water flow is low,
except during emergency situations where the accumulated silt would adversely
affect the hydraulic capacity of the nullah or where flooding risk is imminent,
or when complaints on environmental nuisance associated with the accumulated
silt are received. Moderate
siltation would generally be allowed to accumulate, and removal of excess silt
would be carried out at locations where it would impede water flow. Maintenance works would also be undertaken
for the DWFI system on an as-needed basis and frequent maintenance (i.e.
monthly) would not be required. The
maintenance practices and frequency would be similar to the existing
maintenance works undertaken by the DSD.
Such small-scale maintenance would require only light mechanical equipment
such as a small loader and/or a small crane truck. Hand-held equipment would be used for
vegetation removal. Therefore, adverse
impacts from dust and gaseous emission are not expected.
3.6.2.2 While the odour nuisance of TWN is
anticipated to be alleviated with the implementation of DWFI system under the
Project and treatment wetlands to intercept / polish the polluted discharges
from drainage outlets along the nullah, as well as with the modification of
channel bed downstream of TWN’s low flow channel near its confluence with Shing
Mun River near Man Lai Court to improve the excessive accumulation of silt
brought by tidal influence due to the flat and uneven nullah bed in front of
the broad-crested weir, desilted materials from the maintenance/desilting works
may be found to be odorous when exposed to air.
While minor odour impact may arise from maintenance/desilting works, the
desilted materials will be properly covered with tarpaulin / contained in
watertight container on-site immediately and be located as far away from the
ASRs as possible and be transported off-site by trucks for disposal of at
strategic landfill within one day. As
such, any odour impact during the maintenance would be temporary and confined
to the areas of maintenance works that it would be well-controlled through good
site practices described in Section 3.7.
No adverse odour impact would be anticipated.
3.7.1.1
Sufficient
dust suppression measures as stipulated under the Air Pollution Control
(Construction Dust) Regulation (Cap. 311R) and good site practices such as
enclosing stockpiles of sand with three-side enclosure, covering the dusty
materials with clean impervious sheet, water spraying of all access roads and
site areas, and good house-keeping of the site should
be properly implemented in order to minimise the construction dust
generation. These measures include the
followings:
a) Use of
regular watering, to reduce dust emissions from exposed site surfaces and
unpaved roads particularly during dry weather;
b) Use of
frequent watering in particularly dusty construction areas close to ASRs;
c) Use of
frequent watering or water sprinklers for major haul roads, material
stockpiling areas and other dusty activities within the construction site;
d) 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 should be applied to aggregate
fines;
e) For the
work sites close to the ASR with a separation distance less than 5m, provide
hoardings of not less than 5m high from ground level along the site boundary;
for the work sites close to the ASRs with a separation distance between 5m and
10 m, provide hoardings of not less than 3.5 m high from ground level along the
site boundary; for other work sites, provide hoardings of not less than 2.4 m
high from ground level along the site boundary except for site entrance or
exit;
f) Open
temporary stockpiles should be avoided or covered. Prevent placing dusty material storage plies
near ASRs;
g) Tarpaulin
covering of all dusty vehicle loads transported to, from and between site
locations;
h) Establishment
and use of vehicle wheel and body washing facilities at the exit point of the
site;
i) Imposition
of speed control for vehicles on unpaved site roads. 8 km/hr is the recommended limit;
j) Routing
of vehicles and positioning of construction plants should be at the maximum
possible distance from ASRs;
k) Avoid
position of material stockpiling areas, major haul roads and dusty works within
the construction site close to concerned ASRs;
l) Avoid
unnecessary exposed earth; and
m) During or after the de-bagging
process, the use of cement or dry pulverised fuel ash should be conducted in a
totally enclosed system or facility and effective air pollution control
measures should be placed at any exits or exhaust to avoid potential air
quality influence.
3.7.1.2
Guidelines
stipulated in EPD’s Recommended Pollution Control Clauses for Construction
Contracts should be incorporated in the contract documents to abate dust
impacts. The clauses include:
·
The
Contractor shall observe and comply with the APCO and its subsidiary
regulations, particularly the Air Pollution Control (Construction Dust)
Regulation.
·
The
Contractor shall undertake at all times to prevent dust nuisance as a result of
the construction activities.
·
The
Contractor shall ensure that there will be adequate water supply / storage for
dust suppression.
·
The
Contractor shall devise and arrange methods of working and carrying out the
works in such a manner so as to minimise dust impacts on the surrounding environment, and shall provide experienced personnel with
suitable training to ensure that these methods are implemented.
·
Before
the commencement of any work, the Contractor may be required to submit the
methods of working, plant, equipment and air pollution control system to be
used on the site for the Engineer inspection and approval.
3.7.1.3
In
order to minimise the exhaust emissions from NRMMs during construction phase,
the requirements as stipulated in the Air Pollution Control (Non-road
Mobile Machinery) (Emission) Regulation shall be followed. The following measures are also recommended
to be implemented:
·
Connect
construction plant and equipment to mains electricity supply and avoid use of
diesel generators and diesel-powered equipment;
·
Deploy
electrified NRMMs as far as practicable; and
·
Use
of exempted NRMMs not allowed.
3.7.1.4 The odorous materials from desilting works at downstream tidal zone / excavation at nullah
bed should be contained in watertight container on-site and be transported
off-site by trucks for disposal of at strategic landfill within one day. The materials from excavation at nullah bed
should be well covered on site with tarpaulin and placed as far away from the
ASRs as possible. These odorous
materials should be removed off-site for disposal as soon as possible within 24
hours to avoid any odour nuisance.
During transportation, these odorous materials on the trucks should be
properly covered by tarpaulin sheets to minimise the release of any potential
odour.
3.7.2
Operational Phase
3.8
Evaluation
of Residual Impacts
3.8.1
Construction Phase
3.8.1.1 With proper and effective
implementation of the good site practices and mitigation measures as stipulated
in relevant Regulations and proposed in Section
3.7, no adverse residual air quality
impact would be expected.
3.8.2
Operational Phase
3.9
Environmental
Monitoring and Audit
3.9.1.1
No
adverse air quality impact due to the construction of the Project would
therefore be anticipated. Nonetheless,
dust monitoring is recommended near mid-stream TWN (sections 2 to 4
of TWN) during construction phase to ascertain that there would be
no adverse cumulative dust impacts at the nearby sensitive receivers due to this Project and the concurrent construction with
the interfacing Revised Trunk Road T4, which site
area overlaps with this Project.
Regular weekly site environmental audit is also recommended to ensure
the implementation of recommended mitigation measures during construction
phase. Details of the monitoring and
audit programme are contained in a stand-alone EM&A Manual. No EM&A programme is required during
operational phase.
3.10.1.1 The potential air quality impacts
arising from the construction of the Project would be related to fugitive dust
emissions from construction works and gaseous emissions from the use of PME,
and odour nuisance from desilted / excavated materials
generated during the desilting at downstream tidal zone / excavation works in the
nullah. In view of the small scale of the Project, the air quality impacts would
be localised and minor, and would be well controlled through the implementation
of good site practices and dust suppression measures stipulated in the Air Pollution Control (Construction Dust) Regulation as well as the proposed good site practices to minimise the exhaust emissions from NRMMs and odour
nuisance from handling of desilting/excavated
materials. Dust monitoring and regular
weekly site audit are recommended to be carried out during construction phase
in order to confirm that the mitigation measures are properly implemented and
are working effectively. No adverse air quality impact due to the construction of
the Project would therefore be anticipated.
3.10.1.2 No adverse air quality impact due to
the operation of the Project would be anticipated. With the implementation of DWFI system and
treatment wetlands under the Project the existing dry weather flows from
drainage outlets along TWN would either be intercepted and diverted to the
existing sewerage
system for conveying to Shatin Sewage Treatment Works for treatment by the DWFI system, or be discharged into the
treatment wetlands installed at drainage outlets for in-situ polishing. Furthermore, with the modification of channel
bed downstream of TWN’s low flow channel near its confluence with Shing Mun
River near Man Lai Court, the excessive accumulation of silt brought by tidal
influence due to the flat and uneven nullah bed in front of the broad-crested
weir would be greatly reduced. The odour nuisance from TWN would be
alleviated as a result of the operation of the Project. Any odour emission generated from exposed
desilted materials during the routine maintenance works would be temporary and
confined to the areas of maintenance works that it would be well-controlled
through good site practices. No adverse
air quality impact due to the operation of the Project would be anticipated.