3      aIR qUALITY.. 2

3.1       Introduction. 2

3.2       Environmental Legislation, Policies, Plans, Standards and Criteria. 2

3.3       Description of the Environment 2

3.4       Sensitive Receivers. 2

3.5       Identification of Environmental Impacts. 2

3.6       Assessment Methodology. 2

3.7       Prediction and Evaluation of Environmental Impacts. 2

3.8       Mitigation of Adverse Environmental Impacts. 2

3.9       Evaluation of Residual Impacts. 2

3.10     Environmental Monitoring and Audit 2

3.11     Conclusion. 2

 

List of Tables

 

Table 3.1         Hong Kong Air Quality Objectives. 1

Table 3.2         Tunnel Air Quality Guidelines (TAQG) 2

Table 3.3         Annual Average Concentrations of Pollutants in 2006. 2

Table 3.4         Details of Air Sensitive Receivers. 3

Table 3.5         Emission Factors for Construction Activities and Wind Erosion. 9

Table 3.6         Different Major Dust Generating Activities in the Worst Case Scenarios during Construction Phase  12

Table 3.7         Annual Average Concentrations of Pollutants in Past Five Years. 14

Table 3.8         Vehicle Classes in EMFAC-HK Model 15

Table 3.9         Emission Factors for Year 2016 for Different Vehicle Classes (EMFAC-HK) 20

Table 3.10       Portal and Ventilation Building Emissions. 22

Table 3.11       Design of Ventilation Buildings. 23

Table 3.12       Summary of Odour Patrol Results in Year 2006 Survey. 27

Table 3.13       Summary of Odour Patrol Results in Year 2007 Survey. 28

Table 3.14       Results of Olfactometry Analysis (Year 2006) 32

Table 3.15       Results of Olfactometry Analysis (Year 2007) 32

Table 3.16       Existing Odour Emission Inventory for the Worst Case Scenario. 34

Table 3.17       Conversion Factors to 5-second Mean Concentration. 35

Table 3.18       Predicted Cumulative Maximum 1-hour Average TSP Concentrations at 1.5m above ground  37

Table 3.19       Predicted Cumulative Maximum 24-hour Average TSP Concentrations for at 1.5m above ground  38

Table 3.20       Predicted Cumulative Maximum 1-hour Average TSP Concentrations at 5m above ground  39

Table 3.21       Predicted Cumulative Maximum 24-hour Average TSP Concentrations at 5m above ground  40

Table 3.22       Predicted Cumulative Maximum 1-hour Average NO2 Concentrations at the Representative ASRs at Different Elevations. 42

Table 3.23       Predicted Cumulative Maximum 24-hour Average NO2 Concentrations at the Representative ASRs at Different Elevations. 44

Table 3.24       Predicted Cumulative Maximum 24-hour Average RSP Concentrations at the Representative ASRs at Different Elevations. 46

Table 3.25       Predicted Odour Concentrations at the Representative ASRs (Based on the Existing Odour Emission Rates) Under the Worst Case Condition. 48

Table 3.26       Predicted Odour Concentrations at the Representative ASRs (Mitigated Scenario) under the Worst Case Condition. 51

Table 3.27       Number of Hour Exceeding the Odour Criterion at the Representative ASRs (Mitigated Scenario) in a Year  52

 


3                    aIR qUALITY

3.1              Introduction

3.1.1        This section presents an impact assessment of air quality during the construction and operation phases of the WDII and CWB project.  Compared to the previous scheme, the size of reclamation has been decreased in the latest scheme.  Potential construction dust impact is expected to be less.  However, as the tunnel length of the Central-Wan Chai Bypass has been increased, the operational air quality impact arising from vehicular traffic emissions, tunnel ventilation and portal emissions could be an issue.  Odour nuisance associated with the Causeway Bay Typhoon Shelter is an existing environmental problem.  This Project will not create any new odour source during the operational phase.  However, in order to improve the environment, this Project will take the opportunities to mitigate the potential sources of odour nuisance within the Project area so as to alleviate this existing environmental problem as well as to provide an acceptable environment for the future land uses within the project area (including the proposed open space at the northern breakwater). Appropriate air quality mitigation measures for the proposed development are identified under this Study where necessary.      

3.2              Environmental Legislation, Policies, Plans, Standards and Criteria

3.2.1        The criteria for evaluating air quality impacts and the guidelines for air quality assessment are set out in Annex 4 and Annex 12 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM).

Air Quality Objective & EIAO-TM

 

3.2.2        The Air Pollution Control Ordinance (APCO) provides the statutory authority for controlling air pollutants from a variety of sources.  The Hong Kong Air Quality Objectives (AQOs), which must be satisfied, stipulate the maximum allowable concentrations of certain pollutants over specific periods.  The relevant AQOs are listed in Table 3.1.

Table 3.1     Hong Kong Air Quality Objectives

Pollutant

Maximum Concentration (µg m-3) (1)

Averaging Time

1 hour (2)

8 hour (3)

24 hour (3)

Annual (4)

Total Suspended Particulates (TSP)

-

-

260

80

Respirable Suspended Particulates

(RSP) (5)

-

-

180

55

Sulphur Dioxide (SO2)

800

-

350

80

Nitrogen Dioxide (NO2)

300

-

150

80

Carbon Monoxide (CO)

30,000

10,000

-

-

Photochemical Oxidants

(as Ozone, O3) (6)

240

-

-

-

Notes:

(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.

 


3.2.3        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.  Standard mitigation measures for construction sites are specified in the Air Pollution Control (Construction Dust) Regulations.

3.2.4        In accordance with the EIAO-TM, odour level at an air sensitive receiver should meet 5 odour units based on an averaging time of 5 seconds for odour prediction assessment.

 

Air Pollution Control (Construction Dust) Regulation

 

3.2.5        Notifiable and regulatory works are under the control of the Air Pollution Control (Construction Dust) Regulation.  Notifiable works are site formation, reclamation, demolition, foundation and superstructure construction for buildings and road construction.  Regulatory works are building renovation, road opening and resurfacing slope stabilisation, and other activities including stockpiling, dusty material handling, excavation, concrete production etc.  This Project is expected to include both notifiable and regulatory works.  Contractors and site agents are required to inform the Environmental Protection Department (EPD) on carrying out construction works and to adopt dust reduction measures to reduce dust emission to the acceptable level.

 

Practice Note on Control of Air Pollution in Vehicle Tunnels

 

3.2.6        The Practice Note on Control of Air Pollution in Vehicle Tunnels, prepared by the EPD provides guidelines on control of air pollution in vehicle tunnels.  Guideline values on tunnel air quality are presented in Table 3.2.

Table 3.2     Tunnel Air Quality Guidelines (TAQG)

        Air Pollutant

Averaging Time

Maximum Concentration

(mg/m3) (1)

ppm

Carbon Monoxide (CO)

5 minutes

115,000

100

Nitrogen Dioxide (NO2)

5 minutes

1,800

1

Sulphur Dioxide (SO2)

5 minutes

1,000

0.4

Note:      (1) Expressed at reference conditions of 298K and 101.325kPa.

3.3              Description of the Environment

Baseline Conditions

3.3.1        The study area is in Wan Chai, Causeway Bay and North Point.  The nearest EPD air quality monitoring stations are in Central and Central/Western.  The annual average concentrations of the pollutants measured at EPD’s Central / Western and Central air quality monitoring stations in 2006 adjacent to the WDII development area are summarised in Table 3.3.

Table 3.3     Annual Average Concentrations of Pollutants in 2006

Pollutant

Annual Average Concentration in 2006 (mg m-3)

Monitoring Station

CO

862

Central

NO2

54

Central / Western

RSP

53

Central / Western

TSP

78

Central / Western

 

3.4              Sensitive Receivers

3.4.1        The study area is within 500m from the project boundary.  The study area of air quality assessment is shown in Figure 3.1.  Existing and planned Air Sensitive Receivers (ASRs) including domestic premises, commercial buildings, educational institutions, and recreational and leisure facilities have been identified for air quality impact assessment.

3.4.2        The identified representative ASRs are listed in Table 3.4 and the corresponding locations are shown in Figures 3.2 and 3.3.

Table 3.4         Details of Air Sensitive Receivers

ASRs

Section

Location

Existing / Planned Land Use

No. of floors

 

Horizontal Distance (m)

Alignment*

Ventilation Building

Existing

A25

Wanchai

Police Headquarters

G/IC

7

306

357

1

A26

Wanchai

HK Academy for Performing Arts (Office/Performance Hall)

G/IC

9

186

254

1

A27

Wanchai

Arts Centre

G/IC

10

200

175

1

A28

Wanchai

Citic Tower

Commercial

42

160

385

1

A29

Wanchai

Servicemen's Guides Association

Commercial

3

116

228

1

A30

Wanchai

HK Academy for Performing Arts (Open Space)

G/IC

9

160

144

1

A31

Wanchai

Shui On Centre

Commercial

34

190

160

1

A32

Wanchai

Hong Kong Convention & Exhibition Centre (HKCEC)

Commercial

46

60

229

1

A33

Wanchai

Pedestrian plaza

Recreation

0

95

62

1

A34

Wanchai

HKCEC Extension

Commercial

8

100

177

1

A35

Wanchai

Great Eagle Centre

Commercial

27

112

372

1

A36

Wanchai

Causeway Centre (Block A)

Residential

42

178

531

1

A37

Wanchai

Wanchai Swimming Pool

Recreation

3

58

568

1

A38

Wanchai

Wanchai Sports Ground

Recreation

0

74

723

1

A39

Wanchai

SPCA

G/IC

6

62

787

1

A40

Wanchai

Gloucester Road 169-170

Residential

12

306

750

1

A41

Wanchai

Gloucester Road 210

Residential

18

276

870

1

A42

Wanchai

Gloucester Road 226

Residential

22

264

924

1

A43

Causeway Bay

Elizabeth House

Residential

21

231

1023

1

A44

Causeway Bay

Sino Plaza

Commercial

33

182

900

2

A45

Causeway Bay

World Trade Centre

Commercial

34

151

756

2

A46

Causeway Bay

Excelsior Hotel

Commercial

28

147

726

2

A47

Causeway Bay

Riviera Mansion

Residential

15

162

705

2

A48

Causeway Bay

Marco Polo Mansion (northern façade)

Residential

15

174

633

2

A49

Causeway Bay

Marco Polo Mansion (eastern façade)

Residential

15

180

606

2

A50

Causeway Bay

Royal Hong Kong Yacht Club

Recreation

3

59

720

2

A51

Causeway Bay

Police Officers Club (Tennis Courts)

Recreation

0

70

840

2

A52

Causeway Bay

Police Officers Club (Bowling Green)

Recreation

0

116

822

2

A53

Causeway Bay

Police Officers Club

Recreation

3

68

774

2

A54

Causeway Bay

Bowling Green, Victoria Park

Recreation

0

226

438

2

A55

Causeway Bay

Victoria Park Public Swimming Pool

Recreation

0

322

483

2

A56

Causeway Bay

Viking Garden

Residential

25

434

591

2

A57

Causeway Bay

Victoria court

Residential

18

380

534

2

A58

Causeway Bay

Mayson Garden

Residential

24

327

480

2

A59

Causeway Bay

Gordon House

Residential

15

293

471

2

A60

Causeway Bay

Belle House

Residential

24

214

366

2

A61

Causeway Bay

Citicorp Centre

Commercial

36

146

294

2

A62

Causeway Bay

Hoi Tao Building

Residential

30

160

300

2

A63

Causeway Bay

Victoria Centre

Residential

30

63

249

2

A64

Causeway Bay

Seaview Estate

Industrial/

commercial

13

63

282

2

A65

Causeway Bay

Harbour Heights

Residential

44

674

312

2

A66

Causeway Bay

Whitfield Road Rest Garden

Recreation

0

165

318

2

A93

North Point

City Garden (Block 11) (the height of 1st Sensitive Receiver is located at 5m above ground)

Residential

27

16

612

2

A94

North Point

City Garden (Block 6) (the height of 1st Sensitive Receiver is located at 5m above ground)

Residential

27

20

744

2

A95

North Point

Hong Kong Baptist Church Henrietta Secondary School

Educational

N/a

44

810

2

A96

North Point

Provident Centre (Block 1)

Residential

25

46

918

2

A97

North Point

Provident Centre (Block 6)

Residential

25

34

984

2

A98

North Point

Provident Centre (Block 17)

Residential

25

48

1176

2

Future

A70

Central

Central Government Complex

G/IC

N/a

360

564

1

A71

Central

New G/IC site south and east of CITIC Tower

G/IC

20

264

360

1

A73

Central

Waterfront related commercial and leisure uses

Recreation

N/a

42

246

1

A76

Central

Open space at the west of HKCEC

Recreation

N/a

10

132

1

A81

Wanchai

Waterfront related commercial and leisure uses

Commercial

N/a

15

432

1

A91

North Point

A land zone as “CDA(1) near Oil Street

CDA(1)

45

40

414

2

A92

North Point

A land zoned as CDA near Oil Street

CDA

45

32

513

2

A99

Wanchai

OU(Railway Air Intake Location) zone

 

Other use

3.5m above ground

28

246

1

A100

Wanchai

Water Sports Centre

Recreation

N/a

21

894

2

A101

Causeway Bay

Open space at CBTS Breakwater

Other use

N/a

150

306

2

 

*Distance from the edge of Trunk Road/ IECL alignment.

1 Distance from the Central Ventilation Building.

2 Distance from the exhaust vent shaft of the East Ventilation Building.

 

3.4.3        For construction dust impact assessment, the proposed ASRs under WDII Project including ASRs A71, A73, A76, A81, A99, A100 and A101 would only be occupied after the completion of construction activities of WDII Project, therefore, the construction dust impact assessment does not cover these ASRs.  ASRs A91 and A92 are planned ASRs and there is no construction programme for these two ASRs at the time of this assessment, these two ASRs are therefore also not considered in the construction dust impact assessment.  The planned ASR A70 is Central Government Complex which may be occupied during the construction period of WDII Project.  As a conservative approach, ASR A70 was considered in the construction dust impact assessment.  For operational traffic emission impact, all ASRs listed in Table 3.4 are considered in the assessment.

3.4.4        During construction phase of the Project, dredging activities would be undertaken at the CBTS, and waterfronts along Wan Chai and North Point.  There is potential odour impact associated with the dredging and handling of dredged material from CBTS.  During operational phase, this Project will not create any new odour source.  However, odour nuisance associated with the Causeway Bay Typhoon Shelter is an existing environmental problem.  In order to improve the environment, this Project will take the opportunities to mitigate the potential sources of odour nuisance within the Project area so as to alleviate this existing environmental problem as well as to provide an acceptable environment for the future land uses within the project area (including the proposed open space at the northern breakwater).  The odour impact assessment has assessed the existing odour impact in the vicinity of the Causeway Bay Typhoon Shelter and the potential odour impacts on the planned ASRs proposed under WDII Project during the operational phase.  Odour mitigation measures have been formulated to alleviate this existing environmental problem.  The ASRs considered in the odour impact assessment during operational phase include ASRs A76, A81, A100 and A101.

3.4.5        Regarding the corner of CBTS (i.e. the area in the vicinity of POC), in accordance with the RODP, the pavement at that area would not be changed.  The land strip with 1.5m to 4.5m width would not attract pedestrians to stay here.  It is expected that this narrow strip of land will continue to serve as pedestrian walkway, not a sensitive land use.  The area in the vicinity of drainage culvert outfall Q is also a walkway.  No active and passive recreational uses are proposed under the Project along the existing Gloucester Road/Victoria Park Road from the POC to Causeway Bay Flyover.  It is not expected that the land uses along CBTS between POC and Causeway Bay Flyover would be changed.   


3.5              Identification of Environmental Impacts

Construction Phase

Air Quality Impact from Construction Activities

3.5.1        Construction of seawall and filling works are the major construction works during reclamation.  Excavation, materials handling, wind erosion, truck haulage on unpaved roads are other major sources of dust impact.  However, no on-site concrete batching activity will take place within the construction site.  SO2, NO2 and smoke emitted from diesel-powered equipment may also affect the air quality of the study area.

3.5.2        Potential marine traffic emissions from the dredgers would be expected.  However, given that only a maximum of 10 dredgers would be concurrently operated at CBTS and Wan Chai waterfront, the associated emissions should be limited.  In addition, the nearest distance between the dredgers and ASR (A50) at CBTS is 66m while the nearest distance at Wan Chai waterfront is 27m (ASR A32). Therefore, marine traffic emission impact arising from the Project is anticipated to be insignificant.       

3.5.3        For the tunnel works of the Trunk Road, potential dust nuisance is anticipated during excavation and backfilling of the tunnel construction. 

3.5.4        The concurrent works for the CRIII project has also been taken into account in assessing the impacts.

Odour Impact from Dredging Activities

3.5.5        The water quality in the typhoon shelter has been polluted by sewage discharges in the past and sediments deposited on the seabed in the vicinity of storm outfalls.  These sediments may contain high concentrations of organic matter and heavy metals.  The sediments in CBTS would be dredged away when carrying out the temporary reclamation.

3.5.6        For the dredging activities carried out in the vicinity of Police Officers’ Club, the dredging operation will be restricted to only 1 small close grab dredger to minimise the odour impact during the dredging activity.  The dredging rate should be reduced as much as practicable for the area in close proximity to the Police Officers’ Club.  As the sediments may contain highly contaminated mud which may be disposed with the use of geosynthetic containers (details shall refer to Section 6), grab dredger has to be used for filling up the geosynthetic containers on barges.  As there is no programme constraint for the removal of the sediments at the south-west corner of the typhoon shelter in the vicinity of Police Officers’ Club for mitigating the existing odour problem, the dredging rate can be slowed down or restricted to specific non-popular hours in weekdays when it is necessary during construction.


Operational Phase

Traffic Emission Impact

3.5.7        The major sources of traffic emissions include the open road sections and various tunnel portals / ventilation shafts.  In accordance with the engineering design for CWB Main Tunnel, there will be zero portal emission at the eastern tunnel portal, Slip Road 1 and Slip Road 3.  The exit portals will be provided with an extract system with capacity that exceeds the maximum ventilation rate of the tunnel to achieve zero portal emission.  Standby ventilation fans would also be provided to ensure zero portal emission of CWB during all time of the tunnel operation.  Therefore, tunnel portal emission impact on the ASRs in the vicinity is not anticipated.  Other than emissions from tunnel portal, long sections of landscape deck/deckovers may also result in portal emissions.  Within the study area of the Project, there are some existing and planned deckovers which may have portal emissions.  The landscape deckovers identified in the study area are summarized as follows:

·                     Planned deckover along Road P2

·                     Landscape deck to HKCEC West

·                     Existing deckover over Expo Drive

·                     Deckover (New Atrium Link) between Expo Drive Central and Convention Avenue

·                     Landscaped deck link to waterfront and ferry pier

·                     Landscaped deck from Victoria Park to CBTS waterfront

·                     Landscaped deck over Trunk Road Portal

3.5.8        The landscape deck to HKCEC West (with width of about 8.5m), landscaped deck link to waterfront and ferry pier (with width of about 12m), and landscaped deck from Victoria Park to CBTS waterfront (with width of about 16 m) are very short (see Figure 2.5), therefore, portal emissions from these three landscape decks are not anticipated.  For the landscaped deck over Trunk Road Portal, only one side of the deckover is supported by solid wall (near the Oil Street site), columns would be used as a support on the other side, hence, no portal emission from this landscape deck is expected.

3.5.9        The overall traffic emission air quality impact for this Project would result from:

·                     background pollutant levels based on five years averaged monitoring data from EPD monitoring station at Central/Western

·                     vehicle emissions from open sections of existing and planned road networks in WDII Project and the CWB

·                     emissions from Central Ventilation Building and East Ventilation Building

·                     portal emissions from the existing Cross Harbour Tunnel (CHT)

·                     portal emissions from the planned deckovers along Road P2

·                     portal emissions from the existing deckover over Expo Drive

·                     portal emissions from the proposed deckover (New Atrium Link) between Expo Drive Central and Convention Avenue.


3.5.10    Air quality impacts associated with road traffic are caused mostly by NO2 and RSP.  The fleet average emission factors of various classes of vehicles were calculated by the EMFAC Model and are shown in Appendix 3.8a.  According to the emission rates derived from the EMFAC Model, the ratio of the emission rate for NO2 (as 20% of NOX) and CO to the corresponding 1-hour average AQO is 0.0041 and 0.0015, respectively.  Detailed calculation of the ratio of the hourly average NO2 and CO emission rates to the corresponding AQO is presented in Appendix 3.8b.  The calculation indicates that NO2 is a more critical criteria air pollutant of concern as compared with CO.  In other words, if the predicted NO2 concentrations comply with the corresponding AQO, CO with lower ratio would also comply with its respective AQO.  NO2 and RSP were selected as the critical traffic air pollutants for the purpose of this assessment.

3.5.11    The tunnel section of the Trunk Road is around 3.5km long.  As confirmed with the tunnel ventilation design engineer, a ventilation system would be provided to maintain the air quality inside the tunnel so as to achieve the EPD recommended standard of 1ppm NO2 concentration within the tunnel in accordance with the “Practice Note on Control of Air Pollution in Vehicle Tunnels”.  The emission rate of CO is more than 44 times of the NO2 emission rate with reference to vehicle emission derived from the EMFAC Mode, however, the ratio of guideline standard of CO (5-minutes) concentration to NO2 (5-minutes) concentration in mg/m3 is 64 to 1.  Therefore, CO would also comply with the standard.  Under the Air Pollution Control (Motor Vehicle Fuel) Regulation, the sulphur content of diesel fuel is required to be less than 0.005%.  In view of the low emission rates relative to the statutory limit, SO2 would also comply with the tunnel air quality limit.

Odour Impact

3.5.12    During operational phase, this Project will not create any new odour source.  An extension / modification of Wan Chai East Sewage Screening Plant is not within the scope of the WDII or CWB project, it is only the reprovisioning of the sewage outfall affected by the reclamation work that is within the scope of the WDII Project.  However, odour nuisance associated with the Causeway Bay Typhoon Shelter is an existing environmental problem.  In order to improve the environment, this Project will take the opportunities to mitigate the potential sources of odour nuisance within the Project area so as to alleviate this existing environmental problem as well as to provide an acceptable environment for the future land uses within the project area.

3.6              Assessment Methodology

Construction Phase

3.6.1        There is potential for SO2, NO2 and smoke to be emitted from the diesel-powered equipment and dredgers being used during the construction phase.  However, the number of such plant required on-site (land based and water based) will be limited and under normal operation, equipment with proper maintenance is unlikely to cause significant dark smoke emissions and gaseous emissions are expected to be minor.  Thus, the AQOs are not expected to be exceeded.  Notwithstanding, plant should be regularly maintained to minimise emissions.


3.6.2        The principal source of air pollution during the construction phase will be dust from the dusty activities as mentioned in Section 3.5.1.  The impact of fugitive dust sources on air quality depends upon the quantity as well as the drift potential of the dust particles emitted into the atmosphere.  Large dust particles (i.e. over 100 mm in diameter) will settle out near the source and particles that are between 30 and 100 mm in diameter are likely to undergo impeded settling.  The main dust impacts are likely to arise from particles less than 30 mm in diameter, which have a greater potential to disperse over greater distances.

3.6.3        According to the USEPA AP-42, construction dust particles may be grouped into nine particle size classes.  Their size ranges are 0 - 1 mm, 1 - 2 mm, 2 - 2.5 mm, 2.5 - 3 mm, 3 - 4 mm, 4 - 5 mm, 5 - 6 mm, 6 - 10 mm and 10 - 30 mm, and the percentage of particles in each class was estimated to be 4%, 7%, 4%, 3%, 7%, 5%, 4%, 17% and 49%, respectively.

3.6.4        The emission rates adopted in the WDII project assessment for different construction activities were based on the USEPA Compilation of Air Pollutant Emission Factors (AP-42), 5th edition.  Table 3.5 gives the relevant clauses for emission factors used in this assessment in AP-42.  Detailed calculation of emission rate is presented in Appendix 3.1.

 

Table 3.5         Emission Factors for Construction Activities and Wind Erosion

Construction Activities

Emission Rate (g/m2/s)

Remark

Road Construction, Building Construction and Material Handling (as Heavy Construction)

E = 3.113426E-05

- 50%  work area

- 75% reduction by water suppression (watering four times a day)

-USEPA AP-42 5th ED., S.13.2.3.3

 

Wind Erosion

E = 1.347666E-06

 

- 50% work area

- AP-42 5th ED., S.11.9  Table 11.9.4

 

3.6.5        The Air Pollution Control (Construction Dust) Regulation specifies that dust suppression measures such as watering should be applied for the construction site.  Dust emission from the site would be reduced by 75% if watering with complete coverage of active construction area four times a day.  This assumption was adopted in the construction dust impact assessment.

3.6.6        As confirmed with the Project Proponent, 10 working hours per day (08:00-18:00) was assumed for the dusty construction works in the assessment.  Wind erosion of open work sites would take place over the whole day.

3.6.7        The following summarises the construction activities during the construction stage of the WDII Project.  The locations of the different reclamation sites are shown in Figure 3.4

Causeway Bay Temporary Reclamation (CBR)

·                     Temporary Relocation Causeway Bay Typhoon Shelter (CBTS)

·                     CBTS Temporary Reclamation Stage 1 (TCBR1W & TCBR1E)

·                     CBTS Temporary Reclamation Stage 2 (TCBR2)

·                     CBTS Temporary Reclamation Stage 3 (TCBR3)

·                     CBTS Temporary Reclamation Stage 4 (TCBR4)

·                     Slip Road 8 & Victoria Park Facilities Reprovisioning

 

Ex-PCWA Temporary Reclamation

·                     Temporary Reclamation PCWA Stage 1 (TPCWAE)

·                     Temporary Reclamation PCWA Stage 2 (TPCWAW)

 

Wan Chai Reclamation (WCR)

·                     Wan Chai Reclamation Stage 1 (WCR1)

·                     Wan Chai Reclamation Stage 2 (WCR2)

·                     Wan Chai Reclamation Stage 3 (WCR3)

·                     Wan Chai Reclamation Stage 4 (WCR4)

·                     New Ferry Pier Reprovisioning & Demolish Existing Pier

·                     Helipad Reprovisioning at HKCEC

·                     Roads

 

HKCEC Reclamation

·                     HKCEC Reclamation Stage 1 (Water Channel) (HKCEC1)

·                     HKCEC Reclamation Stage 2 (HKCEC2E & HKCEC2W)

·                     MTR Tunnel Crossing

·                     HKCEC Reclamation Stage 3 (HKCEC3E & HKCEC3W)

·                     Roads

 

Cross Harbour Watermains

·                     Submarine Pipeline

·                     Land Section

 

North Point Reclamation (NPR)

·                     North Point Reclamation Stage 1 (NPR1)

·                     North Point Reclamation Stage 2 (NPR2E & NPR2W)

 

Construction of IECL

·                     IECL Connection Work

·                     East Portal and IEC Connection

 

Construction of Central Interchange

Tunnel Building and Installation

·                     East Ventilation Building

·                     Administration Building

·                     Central Ventilation Building

 

3.6.8        Beside the Wan Chai development, some construction activities would be undertaken within 500m from the boundary of WDII development area.  The construction period of whole CRIII Project is from February 2003 to September 2012.  The interfacing of CRIII dusty construction activities would be from end 2008 to the 1st quarter of 2012.  The concurrent dusty construction activities undertaken within 500 m from the boundary of the WDII development area are summarized as follows. 

Construction of CWB Tunnel Under CRIII Project

·                     CWB Tunnel at Initial Reclamation Area East

·                     CWB Tunnel at Final Reclamation Area East

 

3.6.9        Based on the construction programme (Appendix 2.5) and the number of dusty activities on site, six worst-case scenarios for the development works have been identified throughout the construction period and are shown in Table 3.6.  Overall, the scenarios presented are considered to be representative of the worst case.  The figures showing locations of dusty construction site areas for each scenario are presented in Figures A3.1 to A3.6 in Appendix 3.1.


Table 3.6         Different Major Dust Generating Activities in the Worst Case Scenarios during Construction Phase

Period

2009 – Early 2010

Mid 2010 – Early 2011

Mid 2011 – Early 2012

Mid 2012 – Early 2013

Mid 2013 – Early 2014

Mid 2014-2016

Worst month

Jan 2010

Aug 2010

April 2012

Feb 2013

Nov 2013

Apr 2015

Activities

Scenario 1

Scenario 2

Scenario 3

Scenario 4

Scenario 5

Scenario 6

1

TCBRIE–

Filling

TCBR1E –

CWB Tunnel

TCBR1W – CWB Tunnel

TCBR3 – CWB Tunnel

TCBR3 – CWB Tunnel

TCBR4-CWB Tunnel

2

TCBRIW – Filling

TCBR1W – CWB Tunnel

TCBR2 – CWB Tunnel

TCBR4 – Filling

TCBR4 – CWB Tunnel

TPCWAW-CWB Tunnel

3

TCBRIE –

CWB Tunnel

TCBR2 –

CWB Tunnel

TCBR3 – CWB Tunnel

TPCWAW – CWB Tunnel

Slip Rd 8 & Victoria Park Reprovisioning

Realignment Hung Hing Road

4

TCBR2 –

Filling

TPCWAE –  CWB Tunnel

TPCWAE – CWB Tunnel

WCR2 – Promenade

TPCWAW – CWB Tunnel

Road P2 from Fleming Road to Marsh Road

5

TPCWAE – CWB Tunnel

WCR1 - Drainage

WCR2 – CWB Tunnel

WCR3 – Filling

WCR3 – CWB Tunnel

Mainline to IEC

6

WCR1 – Filling

WCR1 – Cooling Water

HKCEC2E – Filling

WCR4 – Filling

WCR4 – CWB Tunnel

 

7

WCR1 – CWB Tunnel

WCR1 – CWB Tunnel

HKCEC2W – Filling

WCR4 – Drainage

HKCEC2E – Drainage

 

8

New Ferry Piers

HKCEC1 – Cooling Water

HKCEC3E – Filling

HKCEC2W – CWB Tunnel

HKCEC2W – Drainage

 

9

HKCEC1 – Cooling Water

MTR - Piling

HKCEC3E – Drainage

HKCEC3W – CWB Tunnel

HKCEC2E – CWB Tunnel

 

10

HKCEC2E - Filling

NPR1 – CWB Tunnel

HKCEC3W – Drainage

HKCEC3E – CWB Tunnel

HKCEC2W – CWB Tunnel

 

11

Cross Harbour Watermains – Land Sections

NPR2E – Filling

HKCEC3E – CWB Tunnel

IEC Connection Work

HKCEC3E – CWB Tunnel

 

12

NPR1 – CWB Tunnel

CRIII – CWB Tunnel at Initial Area East

NPR2W – CWB Tunnel

East Ventilation Building

HKCEC3W – CWB Tunnel

 

13

NPR2E – Filling

CRIII – CWB Tunnel at Final Area West

 

 

 

 

14

NPR2W – CWB Tunnel

CRIII – CWB Tunnel at Final Area East

 

 

 

 

15

CRIII – CWB Tunnel at Initial Area East

 

 

 

 

 

16

CRIII-CWB Tunnel at Final East

 

 

 

 

 


3.6.10    Fugitive Dust Model (FDM) (1993 version) was used to assess potential dust impact from the construction works.  The worst case meteorological data was used to predict the 1-hour and 24-hour average TSP concentrations at representative discrete ASRs close to the construction works.  Since the construction activities would be undertaken at ground level and underground level, the worst dust impact on the ASRs would be at the ground floor of the ASRs.  The height of 1.5m above ground, which is the breathing level of human, was adopted for the construction dust impact assessment.  As there are some ASRs at the podium level, assessment for ASRs at 5m above ground was also included in the assessment.  The meteorological data used in the model were:

·                     Wind speed:                     1 m/s

·                     Wind direction:                        360 wind direction

·                     Stability class:                  D (daytime) & F (night time)

·                     Surface roughness:          1m

·                     Mixing height:                  500 m

 

3.6.11    Daily TSP concentrations were calculated as follows:

Daily TSP concentration = (number of working hour)/24 ´ (1-hour average maximum TSP concentration during working hours) + (number of non-working hour)/24 ´ (1-hour average maximum TSP concentration during non-working hours) + Background

 

3.6.12     The background TSP concentration of 77 mg/m3, based on the latest five years average monitoring data from EPD’s Central/Western monitoring station, was adopted as an indication of the future TSP background concentration.  As the monitoring data in year 2001 and 2002 were below their respective minimum data requirement of 66% for number of data within the period, therefore, the annual average concentration of TSP was calculated based on the data in Year 2000 and 2003-2006. 

Operational Phase

Vehicular Emission Impact (Open Road)

3.6.13    The overall traffic air quality impact for this Project would result from the following sources and the locations of portals and ventilation building emissions are indicated in Figure 3.5:

·                     background pollutant levels based on five years averaged monitoring data from EPD’s monitoring stations at Central/Western

 

·                     vehicle emissions from open sections of existing and planned road networks (e.g. Trunk Road) in WDII Project and CWB Project

 

·                     emissions from Central Ventilation Building and East Ventilation Building

 

·                     portal emissions from the existing Cross Harbour Tunnel (CHT)

 

·                     portal emissions from the planned deckovers along Road P2

 

·                     portal emissions from the existing deckover over Expo Drive

 

·                     portal emissions from the proposed deckover (New Atrium Link) between Expo Drive Central and Convention Avenue


3.6.14    The tunnel of Trunk Road Eastbound, CWB Slip Road 3 and Slip Road 1 would be provided with an extraction system with capacity that exceeds the maximum ventilation rate of the tunnel, and the in-tunnel emissions would be exhausted at the vent shaft of East Ventilation Building and Central Ventilation Building.  Therefore, the tunnel exit portals of these two slip roads and trunk road eastbound would have zero portal emissions.

Background Concentration

3.6.15    The annual average concentrations of the pollutants measured at EPD’s Central / Western air quality monitoring station in the past five years were adopted as the background air quality within and adjacent to the Project area.  As the monitoring data in year 2001 and 2002 were below their respective minimum data requirement of 66% for number of data within the period, therefore, the annual average concentration of NO2, and RSP were calculated based on the data in Year 2000 and 2003 – 2006. 

3.6.16    Table 3.7 summarises the annual average concentrations of the pollutants considered as background concentrations for the cumulative impact assessment.

Table 3.7     Annual Average Concentrations of Pollutants in Past Five Years

Pollutant

Annual Average Concentration in Past Five Years (2000, 2003-2006) at Central/Western Station (mg m-3)

NO2

55

RSP

54

       

Vehicle Emissions from Open Sections of Existing and Planned Road Networks

3.6.17    The CALINE4 dispersion model was used for calculation of the 1-hour average NO2, 24-hour average NO2 and 24-hour average RSP concentrations.  Open sections of existing and planned road networks within 500 m from the boundary of the WDII project area are considered in the model and are listed as follows:

·                     new roads in the WDII

·                     new roads in the Central Reclamation Phase III (CRIII)

·                     the Trunk Road & IECL

·                     the existing roads (including Island Eastern Corridor, Victoria Park Road, Gloucester Road, Harcourt Road, Causeway Road, Hennessy Road and Queensway)

3.6.18    The predicted morning peak hour traffic flows and vehicle mixes for the road networks in 2031, which is higher than the afternoon peak traffic flow, were used for the assessment of the worst-case air quality scenario.  The projected 2031 morning peak hour traffic flows and vehicle compositions are attached in Appendix 3.2.


Fleet Average Emission Factors

Vehicle Classes

3.6.19    EMFAC-HK model was adopted to estimate the vehicle emission rates and inventories of exhaust, carbon monoxide, oxides of nitrogen and particulate matter. 

3.6.20    The “vehicle fleet” refers to all motor vehicles operating on roads within this Study Area.  The modelled fleet was broken down into 16 vehicle classes based on the information as shown in Table 4.4 (Registration and Licensing of Vehicle by Fuel Type) of the “Transport Monthly Digest (May 2006)” and the vehicle group classification was based on the definition in the “The Annual Traffic Census 2005 – Appendix F Vehicle Classification System”. 

3.6.21    Referring to “Transport Monthly Digest (May 2006)”, there were only 0.5% of private car using diesel fuel.  It was therefore assumed that all private cars would be grouped as “petrol private car” in the model in view of negligible value.  The “Transport Monthly Digest (May 2006)” also indicated that there were 3% light good vehicle using petrol fuel.  Besides, in accordance with the Up to Date Vehicle Licensed Number by Age and Technology Group Fractions launched on EPD’ website, the % of LGV under MC1 is less than 7% of the total vehicle of MC1.  Moreover, refer to EPD’s Guideline on Modelling Vehicle Emissions Appendix 2 Implementation Schedule of Vehicle Emission Standards in Hong Kong, the implementation schedule of diesel LGV emission standards were later than petrol private car.  As a conservative approach, all light good vehicles would be grouped as “diesel light good vehicle”.  The 16 vehicle classes which were modelled in EMFAC-HK are summarized in Table 3.8.

Table 3.8     Vehicle Classes in EMFAC-HK Model

Vehicle Class

Description

Fuel Type

Gross Vehicle Weight

MC1

Petrol Private Cars (PC) & Light Goods Vehicles (LGV)

Petrol

all

MC3

Diesel Private Cars & Light Goods Vehicles<2.5t

Diesel

<=2.5t

MC4

Diesel Private Cars & Light Goods Vehicles 2.5-3.5t

Diesel

>2.5-3.5t

MC5

Public Light Buses

LPG, Diesel

all

MC6

Light Goods Vehicles >3.5t

Diesel

>3.5-5.5t

MC7

Medium & Heavy Goods Vehicles with GVW 5.5-15t

Diesel

>5.5-15t

MC8

Medium & Heavy Goods Vehicles with GVW >=15t