11.2 The criteria for evaluating air quality impacts and the guidelines for air quality assessment are laid out in Annex 4 and Annex 12 of the EIAO-TM, respectively.
11.3 The Air Pollution Control Ordinance (APCO) provides the statutory authority for controlling air pollutants from a variety of sources. The Hong Kong Air Quality Objectives (AQOs), which stipulate the maximum allowable concentrations over specific periods for typical pollutants, should be met. The relevant AQOs are listed in Table 11.1.
Table 11.1
|
Pollutant |
Maximum Concentration (µg m-3) (1) |
|||
|
Averaging Time |
||||
|
1 hour (2) |
8 hour (3) |
24 hour (3) |
Annual (4) |
|
|
- |
- |
260 |
80 |
|
|
Respirable Suspended Particulates (RSP) (5) |
- |
- |
180 |
55 |
|
|
800 |
- |
350 |
80 |
|
Nitrogen Dioxide (NO2) |
300 |
- |
150 |
80 |
|
Carbon Monoxide (CO) |
30,000 |
10,000 |
- |
- |
|
Photochemical Oxidants (as Ozone, O3) (6) |
240 |
- |
- |
- |
Note:
(1)
Measured
at 298 K and 101.325 kPa.
(2)
Not to
be exceeded more than three times per year.
(3)
Not to
be exceeded more than once per year.
(4)
Arithmetic
mean.
(5)
Suspended
particulates in air with a nominal aerodynamic diameter of 10 mm or smaller.
(6)
Photochemical
oxidants are determined by measurement of ozone only.
11.4 The EIAO-TM stipulates that the hourly TSP level should not exceed 500 mgm-3 (measured at 25oC and one atmosphere) for construction dust impact assessment. Mitigation measures for construction sites have been specified in the Air Pollution Control (Construction Dust) Regulations.
11.5 Notifiable and regulatory works are under the control of Air Pollution Control (Construction Dust) Regulation. Notifiable works are site formation, reclamation, demolition, foundation and superstructure construction for buildings and road construction. Regulatory works are building renovation, road opening and resurfacing, slope stabilisation, and other activities including stockpiling, dusty material handling, excavation, concrete production, etc. This Project is expected to include notifiable works (demolition, foundation and superstructure construction) and regulatory works (temporary stockpile, dusty material handling, excavation and concrete production). 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.
11.6 Major stationary air polluters such as power plant, incinerator, crushing plant, which are classified as Specified Processes (SP) in the APCO, are subject to a more stringent emission control. The operation of the following facility is classified as SP under the APCO.
§ Operation of Stone Crushing Plant in which the processing capacity exceeds 5000 tonnes per annum and in which stones are subjected to any size reduction or grading by a process giving rise to dust, not being any works described in any other specified process.
11.7 A licence is required for the operation of these processes under Part IV of the ordinance. Application for licence should be made to EPD. EPD may either grant or refuse to grant a licence subject to whether the applicant can fulfil the environmental standards to avoid causing air pollution. If EPD decides to grant the licence, a set of conditions will be imposed to ensure the adequate prevention of the discharge of air pollutant emissions.
11.8
The proposed alignment of the
WIL is from Sheung Wan, via Sai Ying Pun and
11.9 There is currently a Environmental Protection Department (EPD) fixed air quality monitoring station located within the study area, namely Central/Western monitoring station (situated at the Upper Level Police Station, High Street, Sai Ying Pun). The annual averages of pollutants in mg m-3 monitored at this station for the Year 2005 & 2006 are summarized in Table 11.2.
Table 11.2 EPD Air Quality Monitoring Data at Central/Western Station in 2005 & 2006
|
Pollutant |
Annual Average Concentration (μg/m3) |
|
|
2005 |
2006 |
|
|
SO2 |
22 |
23 |
|
NO2 |
58 |
54 |
|
Ozone |
36 |
38 |
|
TSP |
81 |
78 |
|
RSP |
54 |
53 |
Note: Bold value - Exceedance of AQO
11.10 In accordance with Annex 12 of the EIAO-TM, representative air sensitive receivers (ASRs) in the proximity of the construction sites, temporary stockpiles and crushing plants/barging points were identified. The representative ASRs are listed in Table 11.3 to 11.5 and their locations are illustrated in Figure 11.1 to 11.3.
Table 11.3 Representative
Air Sensitive Receivers in the vicinity of
|
ID No. |
Location |
Use |
Distance between ASR and
closest work boundary(m) |
|
K1 |
|
Residential |
12
|
|
|
Urban Council |
GIC |
4 |
|
K3 |
Luen Tak Apartments |
Residential |
25 |
|
K4 |
|
Residential |
42 |
|
K5 |
|
Residential |
15 |
|
K6 |
|
Residential |
24 |
|
K7 |
Kwun Lung Lau Block D |
Residential |
15 |
|
K8 |
|
Open
Space |
9 |
|
K9 |
Sincere Western House |
Residential |
57 |
|
K10 |
Centenary House Block 2 |
Residential |
126 |
|
K11 |
|
Open
Space |
38 |
|
K12 |
The Merton Block 1 |
Residential |
28
|
|
K13 |
Cayman Rise |
Residential |
63 |
|
K14 |
|
Industrial |
18
|
|
K15 |
Victoria Public Mortuary |
GIC |
3 |
|
K16 |
|
Residential |
10 |
|
K17 |
|
Residential |
11 |
|
K18 |
HKIVE
(Tsing Yi) |
Education
Institute |
25 |
|
K19 |
School
at |
Education
Institute |
26 |
|
K20 |
|
Recreational |
461 |
Table 11.4 Representative Air Sensitive Receivers in the vicinity of University Station Work Site during Construction Phase
|
ID No. |
Location |
Use |
Distance between ASR and
closest work boundary(m) |
|
U1 |
The |
Education
Institute |
7 |
|
U2 |
The Belcher’s, Tower 3 |
Residential |
8 |
|
U3 |
|
Residential |
11 |
|
U4 |
Hillview Garden, Block 5-8 |
Residential |
18 |
|
U5 |
|
Residential |
9 |
|
U6 |
Wing Fu Lau |
Residential |
9 |
|
U7 |
Western Court, Block 1 |
Residential |
3 |
|
U8 |
The Belcher’s, Tower 8 |
Residential |
26 |
|
U9 |
Sun Court |
Residential |
34 |
|
U10 |
|
Open Space |
46 |
|
U11 |
New
Fortune House, Block A |
Residential |
59 |
Table 11.5 Representative Air Sensitive Receivers in the vicinity of Sai Ying Pun Station Work Site during Construction Phase
|
ID No. |
Location |
Use |
Distance between ASR and
closest work boundary(m) |
|
S1 |
Bon-Point |
Residential |
5 |
|
S2 |
No. 18-20 Eastern St |
Residential |
4 |
|
S3 |
|
Residential |
4 |
|
S4 |
Chung Ching House |
Residential |
3 |
|
S5 |
Ka |
Residential |
14 |
|
S6 |
|
Residential |
2 |
|
S7 |
Ka On
Building |
Residential |
4 |
11.11
The construction tasks in the
Project include demolishment of some existing structures, construction of three
proposed stations (Kennedy Town Station, University
Station and Sai Ying Pun Station), construction of the WIL tunnel from Sheung
Wan Station to Kennedy Town Station, permanent vent shafts for WIL and temporary
construction shafts. In addition, there are two rock crushers to be installed
at surface works areas, one temporary magazine site under
the western side of
11.12 There is one single stage (secondary crushing) rock crusher with screening process, one temporary stockpile and one barging point (Barging Point 1) at the Kennedy Town Abattoir site. The rock materials from the Kennedy Town Station site would be transported to this rock crusher for processing. The rock crusher with screening processing and the receiving point (unloading of rocks/stones) of crushing facility would be enclosed. Water spraying would be provided at the unloading point. A dust extraction and collection system would be installed at the rock crushing facility for the treatment of the emissions from rock crushing and screening processes. The potential emission sources at this rock crushing facility would be the unloading activities (from trucks to receiving point of crushing facility) and the discharge point of this dust extraction system.
11.13 After crushing/screening process, there is an enclosed conveyor belt for transporting the crushed materials to the nearby temporary stockpile area. No emission is expected during transportation process except the loading point (continuous drop from conveyor to the stockpile). In order to prevent fugitive emission, water spraying and flexible dust curtains would be provided at this loading point. As confirmed with the Project Proponent, the active area of this temporary stockpile area would be limited to 20% of the total area and the other inactive area would be well covered with impervious sheeting. Water spraying system would be applied to the active area. The material handling and wind erosion at the active stockpile site would be potential dust emission sources. The spoil at the stockpile would be transported to the Barging Point 1 by trucks and the dusty materials would be well covered. The material handling and storage pipes within the stockpile site would be one of the potential dust emission sources.
11.14 The haul roads within the Kennedy Town Abattoir site are all paved and water spraying would be provided on the haul roads to keep wet condition. Vehicles would be required to pass through designated wheel washing facilities before leaving the barging facilities. The trucks would directly unload the spoils to the barges in enclosed tipping hall. The unloading activity is considered as one of the potential dust emission sources though water spraying and flexible curtains would be provided at the unloading point.
11.15 There are two work areas to be considered in the assessment. One of the work sites is located at
11.16 The construction of the station box would require open-cut excavation. The dusty construction activities at these two work areas would include demolishment of concrete structures, soil excavation, material handlings, loading and unloading of excavated materials. Potential dust impact generated from the work sites would be anticipated. For the construction vehicle movement, watering facilities would be provided at every designated vehicle exit point. Since all vehicles would be washed at exit points and vehicle loaded with the dusty materials would be covered entirely by impervious sheeting before leaving the construction site, the dust nuisance from construction vehicle movement outside the work site is unlikely to be significant.
Temporary Magazine Site
11.17 The construction of the WIL would involve substantial amount of rock
excavation of which majority could be carried out by drill and blast
method. A temporary magazine is proposed
to be constructed under the western side of
University Station
11.18 The work sites would include one station box, five station entrance (Entrance A, B1, B2, C1 and C2), a construction shaft and four permanent vent shafts.
11.19 Construction areas for entrance adits, construction shaft and permanent vent shafts would be limited (see Figure 11.2). There would be no demolition activities except Station Entrance B1 (an existing 3 storey height toilet block to be demolished). After site clearance and excavation at the surface area, the secant piles would be installed and then construct overhead gantry crane for mucking out. An enclosed spoil removal hoist (with bucket hopper) would be provided for mucking out. The excavation work would then be carried out in enclosed area and the excavation level would be from ground level to underground level. The spoil removal process would also be conducted within the enclosed structure. No adverse dust impact to the nearby ASRs would be expected. The dusty materials would be well covered by impervious sheeting and the trucks would be washed before leaving the mucking-out area. Therefore, no adverse dust impact from the transportation of spoil would be anticipated.
11.20 The station box of University Station would be constructed underground, not involving open-cut excavation. The spoils at University Station site would be transported to the construction shaft at the open area of Kennedy Town Praya via an underground construction adit and then to Barging Point 3 at Western PCWA via an enclosed conveyor belt system. The whole transporting process is undertaken in the enclosed system, therefore, no adverse dust emission would be expected arising from the University Station site.
Sai Ying Pun Station
11.21 The work sites would include one station box, six station entrance (Entrance A1, A2, B1, B2, B3 and C), one construction shaft and two permanent vent shafts.
11.22 Construction areas for entrance adits, construction shaft and permanent vent shafts would be limited (see Figure 11.3). Demolition activities would be carried out for some entrance adits, however, only one building structure to be demolished of each adit site, for example, Tai Shing House for Entrance A1 and A2, Centre Street Market and Centre Street Cooked Food Centre for Entrance B1 and B2, and Hong Kong Government David Trench Rehabilitation Centre for Entrance C. After site clearance and excavation at the surface area, the secant piles would be installed and then erect a spoil removal hoisting tower at the opening for mucking out purpose. The hoisting tower would be enclosed. The excavation work would be carried out in enclosed area and the excavation level would be from the ground level to the underground level. The spoil removal process would also be conducted within the enclosed structure. No adverse dust impact to the nearby ASRs would be expected. The dusty materials would be covered entirely by impervious sheeting and the trucks would be washed before leaving the mucking-out area. Therefore, no adverse dust impact arising from the transportation of spoil would be anticipated.
11.23 The station box of Sai Ying Pun Station would be constructed underground, not involving open-cut excavation. The spoils at this station site would be transported to the entrance adits for disposal via underground construction adits. As mentioned in Section 11.19, the loading of the spoil to the trucks would be undertaken within the enclosed structure. The dusty materials would be well covered by impervious sheeting and the trucks would be washed before leaving the mucking-out area. Therefore, no adverse dust impact to the surrounding area would be anticipated.
11.24 There are one single stage (secondary crushing) rock crusher with
screening/sorting device, one temporary stockpile and two barging points
(Barging Point 2 and 3) at the
11.25 After rock crushing and screening process, the crushed materials may be transported to nearby stockpile for temporary storage via an enclosed conveyor belt system. Water spraying and flexible dust curtains would be installed at this loading point. As confirmed with the Project Proponent, the active area of this temporary stockpile would be 100% and water spraying would be applied on this open area. The loading point of crushed materials (from rock crushing facility to stockpile), material handling and wind erosion at this active stockpile would be potential dust emission sources.
11.26 The crushed materials from the rock crushers would also be transported to the nearby enclosed tipping hall and then to Barging Point 3 via enclosed conveyor belt system. As mentioned in Section 11.19, the spoils from the University Station would be transported to the enclosed tipping hall and then discharged at Barging Point 3 via enclosed conveyor belt system. In addition, the spoils removed from the University Station entrance adits and Sai Ying Pui Station entrance adits/construction shaft would also be transported to the tipping hall by trucks and then discharged at Barging Point 3 via enclosed conveyor belt system. The possible emission sources for these processes would be unloading process at the tipping hall and the unloading point from enclosed conveyor to the barge. Flexible dust curtains and water spraying would be provided at the unloading point to suppress the dust impact.
11.27 There is another barging point (Barging Point 2) located within
11.28 The haul roads within the
WIL Tunnel
11.29 The construction works for WIL Tunnel would be bored tunnelling and would be performed underground, potential dust impacts from tunnel works would not be anticipated.
Cumulative Dust Impact
11.30 According to the construction programme, some construction
activities of the proposed stations sites would be overlapped. However, these three construction sites would
be located at least 500m away from each other.
There is no other major concurrent project undertaken within the study
area. Therefore, potential cumulative dust impacts generating from the operation
of Kennedy Town Abattoir Site,
11.31
Referring to Section 11.11 –
11.30, potential adverse dust impact would be expected during operation of
Kennedy Abattoir Site, Western PCWA and construction work activities at
11.32 Predicted dust emissions were based on emission factors from USEPA Compilation of Air Pollution Emission Factors (AP-42), 5th Edition. The major dusty construction activities for the Project to be considered in the modelling assessment include:
-
Discharge point from dust extracting system at enclosed rock crushing
facility and its emission include unloading of rocks to the receiving hopper of
rock crushing facility operation of rock crusher and screening process
-
Loading point (loading crushed materials from rock crushing facility onto
stockpile)
-
Material handlings and wind erosion at the active
temporary stockpile area
-
Transportation of the spoils from the active stockpile area to the
enclosed tipping hall of Barging Point 1 by trucks on the paved haul road
-
Unloading point (Barging Point 1) to the barge
-
-
Heavy construction activities including demolition and excavation within
the construction site
-
Wind erosion of open active site
Temporary
Magazine Site
-
Heavy construction activities including excavation and slope works
within the construction site
-
Wind erosion of open active site
-
Discharge point from dust extracting system at enclosed rock crushing
facility and its emission include unloading of rocks to the receiving hopper of
rock crushing facility, operation of rock crusher and screening process
-
Loading point (loading crushed materials from rock crushing facility onto
stockpile)
-
Material handlings and wind erosion at the active
temporary stockpile area
-
Transportation of spoils to the rock crushing
facilities/barging point within
-
Unloading point inside the tipping hall (from truck
unloading to conveyor leading to Barging Point 3)
-
Unloading points at Barging Point 2 and 3.
11.33 According to the preliminary engineering design information, the processing capacity of the rock crushing plants would exceed 5000 tonnes per annum. The operation of crushing plant is therefore classified as SP. The Contractor should apply the SP license under APCO. The requirements and mitigation measures stipulated in the Guidance Note on the Best Practicable Means for Mineral Works (Stone Crushing Plants) BPM 11/1 should be followed and implemented. The dust control measures have been incorporated into the design of the crushing plant, barging facilities and stockpile areas, as presented in Table 11.6, 11.7 and 11.8. These dust control measures have also been taking into account in the assessment.
Table 11.6 Rock Crushing Plants – Dust Emission Design Control Measures
|
Process |
Description |
Dust Emission Design Control
Measures |
|
Unloading of raw materials |
Unloading of stone/rock at the receiving hopper |
The unloading process would be undertaken within enclosed rock
crushing facility. Water spraying would be provided at the unloading point. |
|
Crushing of raw materials |
Crushing the stone/rock with rock crusher. |
The crushing process is the secondary crushing. The rock crushing plant is enclosed and
water spraying system would be installed.
Dust extraction and collection system (80% dust removal efficiency)
would be provided. |
|
Screening process |
Screening the crushed stone/rock |
The crushed stone/rock would be screened by the screening and sorting
facility before transporting to the temporary stockpile via enclosed conveyor. Water spraying system would be
installed. Dust extraction and
collection system (80% dust removal efficiency) would be provided. |
Table 11.7 Temporary Stockpiles – Dust Emission Design Control Measures
|
Process |
Description |
Dust Emission Design Control
Measures |
|
|
||
|
Loading point |
Loading of crushed materials from rock crushing facility onto stockpile |
The transportation would be via an enclosed conveyor belt system and water spraying and flexible dust curtains would be provided at the loading point to suppress the dust impact. |
|
Storage of materials |
Active area for loading & unloading materials |
The active area would be minimized to 20% of the total area of the stock piles. The 80% inactive area would be well covered with impervious sheeting. Water spraying system would be applied on the active area and watering with complete coverage of active area four times a day would be required. |
|
Trucks |
Transportation of materials to Barging Point 1 |
Wheel wash facilities provided at the site exit. The vehicles would be washed before leaving the stockpiles. The spoils would also be well covered before leaving the site in order to minimise generation of dusty materials. The haul roads within the
site would be all paved and water spraying would be provided to keep the wet
condition. |
|
|
||
|
Loading point |
Loading of crushed materials from rock crushing facility onto
stockpile |
The transportation would be via an enclosed conveyor belt system and water spraying and flexible dust curtains would be provided at the loading point to suppress the dust impact. |
|
Storage of materials |
Active area for loading & unloading materials |
Water spraying system would be applied on the active area and
watering with complete coverage of active area four times a day would be
required. |
|
Trucks |
Transportation of materials to Barging Point 2 |
The vehicles would be washed before leaving the stockpiles. The spoils would also be well covered before leaving the site in order to minimise generation of dusty materials. The haul road would be all paved and water spraying would be provided to keep the wet condition. |
Table 11.8 Barging Facilities – Dust Emission Design Control Measures
|
Process |
Description |
Dust Emission Design Control
Measures |
|
|
||
|
Haul road within barging facilities |
Transportation of spoils to Barging Point 1 |
All road surfaces within
the barging facilities would be paved and water spraying would be provided to
keep the wet condition. |
|
unloading of materials |
unloading of spoil materials |
The unloading process would be undertaken within enclosed tipping hall. Flexible dust curtains and water spraying would be provided at the discharge point for dust suppression. |
|
Trucks |
Vehicles leaving the barging facility |
Vehicle wheel washing facilities provided at site exit. |
|
|
||
|
Haul road within barging facilities |
Transportation of spoils to Barging Point 2 |
All road surfaces within
the barging facilities would be paved and water spraying would be provided to
keep the wet condition.
|
|
Unloading of materials |
Unloading of spoil materials from trucks to Barging Point 2 |
The unloading process would be undertaken within the enclosed tipping hall. Flexible dust curtains and water spraying would be provided at the discharge point for dust suppression. |
|
Unloading of spoil materials from enclosed tipping hall to Barging
Point 3 |
The tipping hall would be enclosed structure. The conveyor from tipping hall to the Barging Point 3 would be enclosed. Water spraying and flexible dust curtains would be provided at the receiving point of the tipping hall. Flexible dust curtains and water spraying would be provided at the discharge point of barging facilities for dust suppression. |
|
|
Trucks |
Vehicles leaving the barging facility |
Vehicle wheel washing facilities provided at site exit. |
11.34 The excavation rate, material handling rate, moisture content, silt
content, number of trucks and truck speed are based on the preliminary
engineering design for Kennedy Town Abattoir Site, Kennedy Town Station site
and
Table 11.9 Emission
Factors for Dusty Construction
Activities at
|
Emission Source |
Activity |
Emission Rate |
Remarks |
|
Rock Crushing
Plant at |
Unloading of rock/stone to the receiving hopper of rock crushing plant |
E = 9.93611 x 10 |
Maximum
crushing rate: 85 Mg/hr, 12 operation hours per day. 75% reduction with water spray AP42,
Section 11.19.2 |
|
Secondary
Crushing |
E = =2.83889 x 10- |
Maximum
crushing rate: 85 Mg/hr, 12 operation hours per day. Within
enclosed system and wet suppression Dust extraction and collection system (80% dust
removal efficiency)installed at the rock crushing facility and the discharge
point is located at least 0
AP42,
Section 11.19 |
|
|
Screening |
E =0.0011 g/Mg =5.20463 x 10-3 g/s |
||
|
Stockpile at |
Loading point
from rock crushing facility to temporary stock pile |
E = 1.32697 x 10-2 g/s |
Maximum handling rate: 85Mg/day AP-42, S13.2.4, particle size < 30
um, 1/95 ed AP-42, Table 13.2.4-1, 1/95 ed 90% dust reduction with watering spraying
and flexible dust curtains provided at the loading point |
|
Material Handling and storage piles |
E = = 8.27736 x 10-5 g/m2/s |
E=k´0.0016´[(U/2.2)^1.3/(M/2)^1.4] Maximum Material Handling rate: 85 Mg/hr Particle size multiplier: 0.74 Moisture content: 0.7 % Average wind speed: 2.35 m/s 80%
inactive area (well covered by impervious sheeting) and 20 % active area 75%
reduction by water suppression (complete coverage of active area four
times a day) AP42, Section 13.2.4 |
|
|
Wind
Erosion |
E = 0.85 Mg/hectare/year = 2.69533 x 10-6 g/m2/s |
80%
inactive area (well covered by impervious sheeting) and 20 % active area Watering
on the active area during operation hours AP42, Section 11.9.4 |
|
|
Barging Point at |
Paved haul road
-Transport the spoil from the stockpile to the Barging Point 1 |
E = 1850 g/VKT =4.54004 x 10-4 g/m/s |
E=k´(sL/2)^0.65´(W/3)^1.5 Particle size multiplier: 24g/VKT Silt content: 12% Averaged truck weight: 25tons No. of truck: 106 trucks/day (including return
trip), 90%
reduction by water spraying to keep wet condition AP42, Section 13.2.1. |
|
Unloading
process within enclosed tipping hall. |
E = 1.32697 X 10-2 g/s |
AP-42, S13.2.4, particle size < 30
um, 1/95 ed AP-42, Table 13.2.4-1, 1/95 ed Watering spraying and flexible dust curtains
provided at discharging point. 90%
reduction of dust emission assumed. |
Table 11.10 Emission Factors for Dusty Construction Activities at
|
Emission Source |
Activity |
Emission Rate |
Remarks |
|
Construction Site ( |
Heavy
Construction Activities |
E=2.69 Mg/hectare /month of activity =2.59452 x 10-5 g/m2/s |
50% area actively operating 75%
reduction by water suppression (complete coverage of active construction
area four times a day) AP42, Section
13.2.3 |
|
Wind Erosion (night time) |
E=0.85Mg/hectare /year =1.34767 x 10-6 g/m2/s |
50% active site AP42, Section 11.9.4 |
|
|
Magazine Site (open works area) |
Heavy Construction Activities |
E=2.69 Mg/hectare /month of activity =5.18904 x 10-5 g/m2/s |
50% area actively operating 50%
reduction by water suppression (complete coverage of active construction
area two times a day) AP42, Section 13.2.3 |
|
|
Wind Erosion (night time) |
E=0.85Mg/hectare /year =1.34767 x 10-6 g/m2/s |
50% active site AP42, Section 11.9.4 |
Table 11.11 Emission Factors for Dusty Construction Activities at
|
Emission Source |
Activity |
Emission Rate |
Remarks |
|
Rock Crushing
Plant at |
Unloading of rock/stone to the receiving hopper of rock crushing plant
(Crusher Loading Point) |
E = 1.27361 x 10 |
Maximum
crushing rate: 109 Mg/hr, 12 operation hours per day. 75% reduction With water spray AP42, Section 11.19.2 |
|
Secondary
Crushing |
E =0.0006 g/Mg =3.63889 x 10-3 g/s |
Maximum crushing rate: 109Mg/hr Within
enclosed structure and wet suppression Dust extraction and collection system (80% dust
removal efficiency)installed at the rock crushing facility AP42, Section 11.19 |
|
|
Screening |
E =0.0011 g/Mg =6.67130 x 10-3 g/s |
Handling rate: 109Mg/hr Within
enclosed structure and wet suppression Dust extraction and collection system (80% dust
removal efficiency)installed at the rock crushing facility AP42, Section 11.19 |
|
|
Stockpile at |
Loading point
from rock crushing facility to temporary stock pile |
E = 1.70092 x 10-2 g/s |
Handling rate: 109Mg/hr, 12 operation hours AP-42, S13.2.4, particle size < 30
um, 1/95 ed AP-42, Table 13.2.4-1, 1/95 ed 90% dust reduction with watering spraying
and flexible dust curtains provided at the loading point |
|
Material Handling and storage piles |
E = 0.00561 kg/Mg = 1.16643 x 10-4 g/m2/s |
E=k´0.0016´[(U/2.2)^1.3/(M/2)^1.4] Material Handling rate: 109 Mg/hr Particle size multiplier: 0.74 Moisture content: 0.7 % Average wind speed: 2.35 m/s 100 %
active area 75%
reduction by water suppression (complete coverage of active area four
times a day) AP42, Section 13.2.4 |
|
|
Wind
Erosion |
E = 0.85 Mg/hectare/year = 2.69533 x 10-6 g/m2/s |
Watering
on the active area during operation hours AP42, Section 11.9.4 |
|
|
Barging Point 2 at |
Paved |
E = 1850 g/VKT =6.852893
x 10-4 g/m/s |
E=k´(sL/2)^0.65´(W/3)^1.5 Particle
size multiplier: 24g/VKT Silt
content: 12% Averaged
truck weight: 25tons No. of
truck: 160
truck/day (including return trip) 90% reduction by water spraying
to keep wet condition AP42,
Section 13.2.1 |
|
Unloading
of spoils to the barge within enclosed tipping hall. |
E = 3.56089 x 10-2 g/s |
AP-42, S13.2.4, particle size < 30
um, 1/95 ed 90% reduction by water spray and flexible dust curtain at
discharging point AP-42, Table 13.2.4-1, 1/95 ed |
|
|
Barging Point 3 at |
Unloading of spoils from truck to the conveyor within tipping hall |
E = 1.66675 x 10-3 g/s |
AP42, Section 11.19.2 Handling capacity: 2743 Mg/day 75% reduction by water spraying |
|
Unloading of spoils from the conveyor to the barge |
E = 3.56089 x 10-2 g/s |
AP-42, S13.2.4, particle size < 30
um, 1/95 ed 90% reduction by water spraying and flexible dust curtain
provided at discharging point AP-42, Table 13.2.4-1, 1/95 ed |
11.35 In accordance with the preliminary engineering design for both rock crushing facilities, the dust emission in the rock crushing and screening processes would be extracted to the dust extraction and collection system which would have 80% dust removal efficiency for treatment before discharging into the atmosphere. As advised by the Project Proponent, an active operating area of 50% for Kennedy Town Station construction site and temporary magazine site are assumed at any one time. 12-hour (07:00-19:00) is assumed for the construction period in the assessment.
Dispersion Modelling &
Concentration Calculation
11.36 Fugitive Dust Model (FDM) (1993 version) was adopted to assess potential dust impact from the construction works. The worst case meteorological condition was used to predict the 1-hour and 24-hour average TSP concentrations at representative discrete ASRs in the vicinity of the construction sites. The height of 1.5m (the breathing level of human), 5m, 10m, 15m and 20m above ground were adopted for the construction dust impact assessment. The meteorological data used in the model were:
§ Wind direction: 360 wind directions
§ Stability class: D (daytime) & F (night time)
§ Surface roughness: 1m
11.37 The background TSP level of 78 mg/m3, based on the latest five years (2000, 2003 – 2006) average monitoring data from EPD Central/Western monitoring station, was adopted as an indication of the TSP background concentration during the construction phase. The monitoring data in Year 2001 and 2002 were not considered as their monitoring data were below their respective minimum data requirement of 66% for number of data within that period.
11.38 The predicted cumulative hourly and daily average TSP concentrations at the representative ASRs due to construction activities at Kennedy Town Abattoir Site, Kennedy Town Station site, temporary magazine site and Western PCWA under the worst case scenario are presented in Table 11.12 and 11.13.
11.39 Based on the results indicated in Table 11.12 and 11.13, the predicted 1-hour and 24-hour average TSP at all representative ASRs would comply with the criteria in EIAO-TM and AQO. It is noted that the worst levels would be at 1.5m above ground level. The contour plots of 1-hour and 24-hour average TSP concentrations at 1.5m above ground level are indicated in Figure 11.6 and 11.7. There are no ASRs found to have non-compliance of the 1-hour and 24-hour average TSP criteria in the contour plots.
Table 11.12 Predicted Cumulative Hourly Average TSP Concentrations at Representative Air Sensitive Receivers
|
ASRs |
Cumulative Hourly Average TSP Concentrations
in mg/m3 |
||||
|
1.5m AGL |
5m AGL |
10m
AGL |
15m
AGL |
20m AGL |
|
|
K1 |
369
|
215
|
140 |
114 |
101
|
|
|
398 |
232
|
135 |
100 |
96
|
|
K3 |
282 |
218
|
138 |
100 |
96
|
|
K4 |
271 |
243
|
176 |
131 |
107
|
|
K5 |
350 |
253
|
162
|
120
|
100
|
|
K6 |
308 |
232
|
138 |
102 |
94
|
|
K7 |
408 |
270
|
164 |
118 |
96
|
|
K8 |
385 |
293
|
181 |
130 |
104
|
|
K9 |
204 |
195
|
161 |
130 |
109
|
|
K10 |
141 |
141
|
130 |
118 |
107
|
|
K11 |
114 |
115
|
111 |
106 |
101
|
|
K12 |
109 |
109
|
107 |
103 |
99
|
|
K13 |
130 |
126
|
111 |
102 |
97
|
|
K14 |
283 |
211
|
116 |
100 |
93
|
|
K15 |
312 |
228
|
129 |
121 |
101
|
|
K16 |
354 |
211
|
124 |
99 |
92
|
|
K17 |
335 |
179
|
108 |
100 |
92
|
|
K18 |
293
|
210
|
122 |
98 |
93
|
|
K19 |
366 |
275 |
152 |
100 |
90 |
|
K20 |
95 |
96 |
95 |
93 |
91 |
|
U10 |
323
|
269 |
165 |
108 |
98 |
|
U11 |
259
|
241 |
188 |
140 |
107 |
Note: The background TSP level of 78 mg/m3, have been included in the above results.
The 1-hour average TSP
EIAO-TM criterion: 500 mg/m3.
|
ASRs |
Cumulative 24-Hour Average TSP Concentrations
in mg/m3 |
||||
|
1.5m AGL |
5m AGL |
10m
AGL |
15m
AGL |
20m AGL |
|
|
K1 |
235
|
149
|
110 |
96 |
90
|
|
|
250 |
158
|
107 |
90 |
87
|
|
K3 |
189 |
151
|
108 |
89 |
87
|
|
K4 |
185 |
166
|
129 |
105 |
93
|
|
K5 |
225 |
170
|
121
|
99
|
89
|
|
K6 |
203 |
158
|
109 |
90 |
86
|
|
K7 |
258 |
179
|
122 |
98 |
87
|
|
K8 |
247 |
192
|
131 |
104 |
91
|
|
K9 |
149 |
142
|
121 |
105 |
94
|
|
K10 |
114 |
113
|
106 |
99 |
93
|
|
K11 |
98 |
99
|
96 |
93 |
90
|
|
K12 |
95 |
95
|
93 |
91 |
89
|
|
K13 |
107 |
104
|
96 |
91 |
88
|
|
K14 |
185 |
146
|
98 |
90 |
86
|
|
K15 |
201 |
155
|
104 |
100 |
90
|
|
K16 |
228 |
147
|
102 |
89 |
85
|
|
K17 |
216 |
130
|
94 |
90 |
86
|
|
K18 |
195
|
147
|
101 |
89 |
86
|
|
K19 |
230 |
179 |
116 |
90 |
85 |
|
K20 |
88 |
88 |
87 |
86 |
85 |
|
U10 |
202
|
175 |
123 |
93 |
88 |
|
U11 |
170
|
161 |
134 |
109 |
93 |
Note: The background TSP level of 78 mg/m3, have been included in the above results.
The
24-hour average TSP AQO criterion: 260 mg/m3.
11.40 In view of limited work site areas and most of excavation activities carried out underground level and within covered area, no adverse dust impact to the surrounding environment would be expected with the implementation of standard dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation and good site practices. An underground construction adit and enclosed conveyor belt system would be provided for transportation of spoil from University Station box to the Barging Point 3 via the construction shaft. The whole process would be undertaken in enclosed system and no adverse dust impact would be expected. For the entrance adits/construction shaft, the spoil removal process would be conducted within the enclosed mucking-out area. The dusty materials would be well covered by impervious sheeting and the trucks would be washed before leaving the mucking-out area. Insignificant dust impact arising from transportation of spoils would be anticipated.
11.41 Similar to University Station construction site, the work areas at the above ground level are limited and most construction activities would be carried out underground at Sai Ying Pun Station. Demolishment of some structures at some entrance adits would be required, however, adverse dust impacts would not be anticipated at the nearby ASRs with the implementation of standard dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation and good site practices. Minimal spoil would be removed from the entrance adits sites and construction shaft. The spoil loading activity would be undertaken within enclosed mucking-out area. The spoil materials would be covered entirely by impervious sheeting and the trucks would be washed before leaving the mucking-out area, insignificant dust impacts from the transportation of spoil would be anticipated.
11.42 Dust control measures have been incorporated into the engineering design as presented in Tables 11.6 to 11.8. For rock crushing plants, the requirements and mitigation measures stipulated in the Guidance Note on the Best Practicable Means for Mineral Works (Stone Crushing Plants) BPM 11/1 should be followed and implemented. In addition, implementation of dust suppression measures stipulated in the Air Pollution Control (Construction Dust) Regulation and good site practices should be carried out to further minimize construction dust impact.
§
Use of regular watering, with
complete coverage, 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 dusty material storage piles to reduce emissions. Where this is not practicable owing to
frequent usage, watering shall be applied to aggregate fines.
§ Open stockpiles shall be avoided or covered. Where possible, prevent placing dusty material storage piles near ASRs.
§ 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 wind shield and
dust extraction units or similar dust mitigation measures at the loading
points, 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.
§ Imposition of speed controls for vehicles on unpaved site roads. 8 kilometers per hour is the recommended limit.
§ Where possible, routing of vehicles and positioning of construction plant should be at the maximum possible distance from ASRs.
§
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.
§ Cement or dry PFA delivered in bulk should be stored in a closed silo fitted with an audible high level alarm which is interlocked with the material filling line and no overfilling is allowed.
§
Loading, unloading, transfer,
handling or storage of bulk cement or dry PFA should be carried out in a
totally enclosed system or facility, and any vent or exhaust should be fitted
with an effective fabric filter or equivalent air pollution control system.
11.43 With the implementation of the mitigation measures as stipulated in the Air Pollution Control (Construction Dust) Regulation, dust control measures and good site practices, the predicted dust impact at ASRs would comply with the TSP criterion in EIAO-TM and AQO.
11.44 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.
11.45 Air quality impacts from the construction works for the Project would mainly be related to construction dust from excavation, materials handling, spoil removal and wind erosion, as well as operation of crushing plants, temporary magazine site, stockpiles and barging facilities. With the implementation of mitigation measures specified in the Air Pollution Control (Construction Dust) Regulation, proposed dust suppression measures, good site practices and dust control measures for the Specified Process (crushing plant) checked by an EM&A programme, no adverse dust impact on the ASRs in the vicinity of the construction sites would be anticipated.