3 Air qUALITY

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 laid out in Annex 4 and Annex 12 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM), respectively.

3.2.2 The Air Pollution Control Ordinance (APCO) provides the statutory authority for controlling air pollutants from a variety of sources. The ordinance encompasses a number of Air Quality Objectives (AQOs) which stipulate maximum concentrations for a range of pollutants, of which Carbon Monoxide (CO), Nitrogen Dioxide (NO₂), Respirable Suspended Particulates (RSP) and Total Suspended Particulates (TSP) are relevant to this study. The relevant AQOs are listed in Table 3.1.

Table 3.1 Hong Kong Air Quality Objectives

Parameter	Maximum Average Concentration (µg m^-3) ⁽¹⁾
	1 Hour ⁽²⁾	8 Hours ⁽³⁾	24 Hours ⁽³⁾	Annual ⁽⁴⁾
NO₂	300	-----	150	80
RSP	-----	-----	180	55
CO	30,000	10,000	-----	-----
TSP	500 ⁽⁵⁾	-----	260	80

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) Not an AQO. However, in addition to the established legislative controls, it is accepted that an hourly-averaged TSP concentration of 500 µg m^-3 should not be exceeded.

3.2.3 The criteria for tunnel quality, which are based on EPD’s Practice Note on Control of Air Pollution in Vehicle Tunnels 1995, are presented in Table 3.2.

Table 3.2 Tunnel Air Quality Criteria

Parameter	Maximum Concentration ^{(1) (2)}
CO	115,000 µg m^-3	100 ppm
NO₂	1,800 µg m^-3	1 ppm
SO₂	1,000 µg m^-3	0.4 ppm

Note: (1) Averaging time is 5 minutes.

(2) Measured at 298 K and 101.325 kPa.

3.2.4 In addition, the visibility in tunnels acts as an indicator of smoke concentration and should be controlled so that extinction coefficient does not exceed 0.005 per meter (over five minutes).

3.3 Description of the Environment

3.3.1 As agreed with the EPD, the annual average concentrations of the pollutants measured at EPD’s Central / Western and Central Station air quality monitoring stations in 1999 have been adopted as the background air quality within and adjacent to the CWB & IECL. Table 3.3 summaries the annual average concentrations of the pollutants in 1999.

Table 3.3 Annual Average Concentrations of Pollutants in 1999

Pollutant	Annual Average Concentration in 1999 (mg m^-3)	Monitoring Stations
CO	1,179	Central
NO₂	56	Central / Western
RSP	53	Central / Western
TSP	81	Central / Western

3.3.2 The annual average concentrations of the pollutants were used as the background concentrations for the cumulative impact assessment.

3.4 Sensitive Receivers

3.4.1 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 ASRs are listed in Table 3.4 and the corresponding locations are shown in Figures 3.1.1 and 3.1.2.

Table 3.4 Locations of Air Sensitive Receivers

ASR	Section	Location	Existing / Planned Land Use	No. of floors	Horizontal Distance (m)
ASR	Section	Location	Existing / Planned Land Use	No. of floors	Alignment*	Ventilation Building
		Existing
A1	Sheung Wan	Shun Tak Centre	Commercial	30	20	648	⁽¹⁾
A2	Sheung Wan	Korea Centre	Residential	13	12	654	⁽¹⁾
A3	Sheung Wan	Wing On Centre	Commercial	24	9	606	⁽¹⁾
A4	Central	Vicwood Plaza	Commercial	27	32	527	⁽¹⁾
A5	Central	Harbour Building	G/IC	26	16	407	⁽¹⁾
A6	Central	Crocodile Building	Commercial	20	214	321	⁽¹⁾
A7	Central	Hang Sang Bank Headquarters	Commercial	25	260	313	⁽¹⁾
A8	Central	Exchange Square III	Commercial	26	246	271	⁽¹⁾
A9	Central	Exchange Square I & II	Commercial	45	208	281	⁽¹⁾
A10	Central	Exchange Square I & II	Commercial	45	280	341	⁽¹⁾
A11	Central	Jardine House	Commercial	46	248	360	⁽¹⁾
A12	Central	Jardine House	Commercial	46	287	384	⁽¹⁾
A13	Central	Statue Square	Recreation	0	313	510	⁽¹⁾
A14	Central	Hong Kong Club Building	Commercial	16	282	561	⁽¹⁾
A15	Central	City Hall	G/IC	11	120	534	⁽¹⁾
A16	Central	City Hall	G/IC	11	244	530	⁽¹⁾
A17	Central	Furama Hotel	Commercial	23	260	619	⁽¹⁾
A18	Central	Hutchison House	Commercial	18	257	683	⁽¹⁾
A19	Central	Bank of America Tower	Commercial	33	256	723	⁽²⁾
A20	Central	PLA Headquarters	Others	4	92	604	⁽²⁾
A21	Central	PLA Headquarters	Others	21	204	648	⁽¹⁾
A22	Central	Far East Financial Centre	Commercial	40	310	630	⁽²⁾
A23	Central	Admiralty Centre	Commercial	48	341	579	⁽²⁾
A24	Central	Harcourt Garden	Recreation	0	328	423	⁽²⁾
A25	Wanchai	Police Headquarters	G/IC	7	306	322	⁽²⁾
A26	Wanchai	HK Academy for Performing Arts	G/IC	9	186	212	⁽²⁾
A27	Wanchai	Art Centre	G/IC	10	200	196	⁽²⁾
A28	Wanchai	Citic Tower	Commercial	42	160	327	⁽²⁾
A29	Wanchai	Servicemen's Guides Association	Commercial	3	116	169	⁽²⁾
A30	Wanchai	HK Academy for Performing Arts	G/IC	9	160	132	⁽²⁾
A31	Wanchai	Shui On Centre	Commercial	34	190	228	⁽²⁾
A32	Wanchai	Hong Kong Convention & Exhibition Centre (HKCEC)	Commercial	46	60	356	⁽²⁾
A33	Wanchai	Pedestrian plaza	Recreation	0	95	146	⁽²⁾
A34	Wanchai	HKCEC Extension	Commercial	8	100	276	⁽²⁾
A35	Wanchai	Great Eagle Centre	Commercial	27	112	494	⁽³⁾
A36	Wanchai	Causeway Centre	Residential	42	178	396	⁽³⁾
A37	Wanchai	Wanchai Swimming Pool	Recreation	3	58	281	⁽³⁾
A38	Wanchai	Wanchai Sports Ground	Recreation	0	74	144	⁽³⁾
A39	Wanchai	SPCA	G/IC	6	62	95	⁽³⁾
A40	Wanchai	Gloucester Road 169-170	Residential	12	298	364	⁽³⁾
A41	Wanchai	Gloucester Road 210	Residential	18	276	300	⁽³⁾
A42	Wanchai	Gloucester Road 226	Residential	22	266	290	⁽³⁾
A43	Causeway Bay	Elizabeth House	Residential	21	242	303	⁽³⁾
A44	Causeway Bay	Sino Plaza	Commercial	33	206	368	⁽³⁾
A45	Causeway Bay	World Trade Centre	Commercial	34	168	493	⁽³⁾
A46	Causeway Bay	Excelsior Hotel	Commercial	28	160	525	⁽³⁾
A47	Causeway Bay	Riviera Mansion	Residential	15	166	564	⁽³⁾
A48	Causeway Bay	Marco Polo Mansion (northern facade)	Residential	15	152	663	⁽³⁾
A49	Causeway Bay	Marco Polo Mansion (eastern facade)	Residential	15	148	703	⁽³⁾
A50	Causeway Bay	Royal Hong Kong Yacht Club	Recreation	3	40	317	⁽³⁾
A51	Causeway Bay	Police Officers Club (Tennis Courts)	Recreation	0	96	301	⁽³⁾
A52	Causeway Bay	Police Officers Club (Bowling Green)	Recreation	0	140	370	⁽³⁾
A53	Causeway Bay	Police Officers Club	Recreation	3	88	375	⁽³⁾
A54	Causeway Bay	Bowling Green, Victoria Park	Recreation	0	124	1006	⁽³⁾
A55	Causeway Bay	Victoria Park Public Swimming Pool	Recreation	0	190	1169	⁽³⁾
A56	Causeway Bay	Viking Garden	Residential	25	304	1247	⁽³⁾
A57	Causeway Bay	Victoria court	Residential	18	262	1251	⁽³⁾
A58	Causeway Bay	Mayson Garden	Residential	24	213	1243	⁽³⁾
A59	Causeway Bay	Gorden House	Residential	15	184	1232	⁽³⁾
A60	Causeway Bay	Belle House	Residential	24	122	1205	⁽³⁾
A61	Causeway Bay	Citicorp Centre	Commercial	36	126	1163	⁽³⁾
A62	Causeway Bay	Hoi Tao Building	Residential	30	120	1257	⁽³⁾
A63	Causeway Bay	Victoria Centre	Residential	30	16	1224	⁽³⁾
A64	Causeway Bay	Seaview Estate	Residential	13	21	1277	⁽³⁾
A65	Causeway Bay	Harbour Heights	Residential	44	17	1319	⁽³⁾
A66	Causeway Bay	Whitfield Road Rest Garden	Recreation	0	64	1153	⁽³⁾
		Future
A67	Central	Comprehensive Development Area Site	Commercial	N/a	103	108	⁽¹⁾
A68	Central	Airport Railway Hong Kong Station	Commercial	N/a	30	54	⁽¹⁾
A69	Central	Future Commercial Buildings and landscaped deck east of new outlying Islands Ferry Piers (CDA site)	Commercial	N/a	58	219	⁽¹⁾
A70	Central	Proposed Central Government Complex	G/IC	N/a	68	500	⁽²⁾
A71	Central	New G/IC site south and east of CITIC Tower (to include the redeveloped HK Red Cross Headquarters)	G/IC	N/a	219	314	⁽²⁾
A72	Central	New G/IC site north of CITIC Tower	G/IC	N/a	27	244	⁽²⁾
A73	Central	Waterfront related commercial and leisure uses	Commercial	N/a	14	185	⁽²⁾
A74	Central	Open space promenade along new reclamation edge	Recreation	N/a	11	512	⁽²⁾
A75	Central	Waterfront related commercial and leisure uses - Festival Market	Commercial	N/a	49	516	⁽¹⁾
A76	Wanchai	Waterfront related commercial and leisure uses	Commercial	N/a	14	86	⁽²⁾
A77	Wanchai	Waterfront related commercial and leisure uses	Commercial	N/a	18	82	⁽²⁾
A78	Wanchai	Grade A Office	Commercial	N/a	68	37	⁽²⁾
A79	Wanchai	Helipad	Others	N/a	196	517	⁽³⁾
A80	Wanchai	Pier	Others	N/a	94	304	⁽³⁾
A81	Wanchai	Exhibition Station – future CDA development	Commercial	N/a	22	400	⁽³⁾
A82	Wanchai	Waterfront related commercial and leisure uses	Commercial	N/a	22	266	⁽³⁾
A83	Wanchai	Waterfront related commercial and leisure uses	Commercial	N/a	28	174	⁽³⁾
A84	Wanchai	Waterfront related commercial and leisure uses	Commercial	N/a	39	66	⁽³⁾
A85	Wanchai	Harbour Museum	G/IC	N/a	93	132	⁽³⁾
A86	Wanchai	Indoor games hall and training pool	G/IC	N/a	16	129	⁽³⁾
A87	Wanchai	5-Star hotel / Commercial	Commercial	N/a	52	399	⁽³⁾
A88	Wanchai	5-Star hotel / Commercial	Commercial	N/a	130	455	⁽³⁾
A89	Causeway Bay	Tin Hau Temple	G/IC	N/a	38	1068	⁽³⁾
A90	Causeway Bay	Indoor Entertainment Centre	G/IC	N/a	36	1061	⁽³⁾

*Distance from the main CWB & IECL alignment.

(1) Distance from the West Ventilation Building.

(2) Distance from the Central Ventilation Building.

(3) Distance from the East Ventilation Building.

3.5 Assessment Methodology

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 emitting 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.

3.5.2 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.

3.5.3 Fugitive Dust Model (FDM) was used to predict the TSP concentration levels. The emission rates 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.

Table 3.5 Emission Factors for Construction Activities

Construction Activities	Reference*
Road Construction, Building Construction and Material Handling (as Heavy Construction)	S.13.2.3.3
Material Handling (Excavation and Backfilling)	S.13.2.4
Truck Haulage	S.13.2.2
Wind Erosion	S.11.9 Table 11.9.4

* AP-42, 5^th Edition

3.5.4 The 1997 meteorological data from the Hong Kong Observatory (Central Station) was used in the FDM to predict the 1-hour and 24-hour averaged TSP concentrations. The data includes hourly-averaged wind speed, wind direction, stability class, ambient temperature and mixing height.

3.5.5 The following summarises the construction stages of the CWB & IECL project. The locations of different construction works are shown in Figures 3.2.1 and 3.2.2.

· CWB & IECL Work Packages (excluding entrusted works):

- Tunnel Section of the Central Interchange (Central Interchange (Tunnel));

- Bridge Section of the Central Interchange (Central Interchange (Building));

- Demolition of part of Rumsey Street Flyover;

- East Section of the IECL (IECL-East);

- West Section of the IECL (IECL-West);

- Tunnel Buildings (includes West Ventilation Building, Central Ventilation Building, East Ventilation Building and Administration Building); and

- E&M and Tunnel Installation.

· CWB entrusted works in Wan Chai Development Phase II (WDII):

- CWB tunnel;

- Slip roads; and

- Tunnel building foundation and ducting structures.

· CWB entrusted works in Central Reclamation Phase III (CRIII):

- CWB tunnel.

3.5.6 Besides the CWB & IECL project, the following is a list of interfacing projects from 2002 to 2012 within 500 m from the study boundary. The locations of different construction works are shown in Figures 3.2.1 and 3.2.2.

· Wan Chai Development Phase II (WDII):

- HKCEC Reclamation Stage 1 – Water Channel (HKCEC1);

- HKCEC Reclamation Stage 2 – West (HKCEC2W);

- HKCEC Reclamation Stage 2 – East (HKCEC2E);

- Wanchai Reclamation Stage 1 – (WCR1);

- Wanchai Reclamation Stage 2 – West (WCR2W);

- Wanchai Reclamation Stage 2 – East (WCR2E);

- Wanchai Reclamation Stage 3 – West (WCR3W);

- Wanchai Reclamation Stage 3 – East (WCR3E);

- Causeway Bay Reclamation Stage 1 – West (CBR1W);

- Causeway Bay Reclamation Stage 1 – East (CBR1E);

- Causeway Bay Reclamation Stage 2 – West (CBR2W);

- Causeway Bay Reclamation Stage 2 – East (CBR2E);

- PCWA Basin Reclamation;

- Pier Construction;

- MTR Tunnel Construction;

- Helipad Construction; and

- Hung Hing Road Flyover Construction.

· Central Reclamation Phase III (CRIII):

- Stage 1 (includes Hinterland Areas, Initial Reclamation Area West (IRAW));

- Stage 2 (includes Hinterland Areas, IRAW and Initial Reclamation Area East (IRAE));

- Stage 3 (includes Hinterland Areas, IRAE, IRAW);

- Stage 4 (includes Hinterland Areas, FRAW, IRAE);

- Stage 5 (includes Hinterland Areas, IRAE, Final Reclamation Area West (FRAW) and Final Reclamation Area East (FRAE));

- Stage 6 (includes FRAW and FRAE);

- Stage 7 (includes FRAW, FRAE and all areas);

- Stage 8 (includes FRAW);

- North Hong Kong Island Line (NHKIL) protection works (within CRIII area); and

- Extended Overrun Tunnel (EOT) entrusted works (within CRIII area).

3.5.7 Public fill is to be used in the reclamation work in WDII area. The major dust generating activities for the public fill are summarised in Appendix 3.1. Based on the sequence of potentially dusty activities on site, ten worst-case scenarios for the public fill are identified and shown in Table 3.6.

Period	2002 – 2004	2005	2006	2007	2008	2009 - 2012
1	CRIII – Stage 5	CRIII – Stage 5	CRIII – Stage 6	CRIII – Stage 6	CRIII – Stage 7	Central Interchange (Tunnel)	Central Interchange (Tunnel)	Central Interchange (Tunnel)	IEC – East	IEC – West
2	CBR1E – Filling	CBR1E – Filling	CBR1W – Filling	CBR1W – Filling	Central Interchange (Tunnel)	CBR2W – Filling	CBR2W – Filling	WCR2 – Drainage	WCR2 – Drainage	Tunnel Buildings
3	WCR1 – Filling	CBR1 – Cooling Water	CBR1 – Drainage	CBR1 – Drainage	Central Interchange (Bridge)	CBR2 – Drainage	CBR2 – Drainage	WCR2W – CWB Tunnel	WCR2W – CWB Tunnel
4	WCR1 – Cooling Water	WCR1 – Filling	CBR1 – Cooling Water	CBR1 – Cooling Water	CBR1 – Drainage	WCR2 – Drainage	WCR2W – Filling	WCR3 – CWB Tunnel	WCR3 - Drainage
5	HKCEC2 – Cooling Water	PCWA Basin Construction	WCR1 – CWB Tunnel	WCR1 – CWB Tunnel	CBR2E – Filling	WCR2E – CWB Tunnel	WCR2 – Drainage	HKCEC2W – CWB Tunnel	HKCEC2 – Drainage
6		HKCEC2 – Cooling Water	WCR3E – Filling	WCR3E – Filling	WCR2E - Filling	WCR3W – Filling	WCR2E – CWB Tunnel		HKCEC2E – CWB Tunnel
7			HKCEC1 – Filling	HKCEC1 – CWB Tunnel	WCR2 – Drainage	HKCEC2W – Filling	WCR3 – CWB Tunnel
8				MTR Tunnel	Pier Construction	Helipad	HKCEC2E – Filling
9							Helipad
10							Hung Hing Road Flyover			`

3.5.8 The working hours of all construction sites were assumed to be 12 hours. Truck speed within the sites was limited to 10 km per hour.

3.5.9 Daily TSP concentrations were calculated as follows:

Daily TSP concentration = 12/24 x (1-hour average maximum TSP concentration during working hours) + 12/24 x (1-hour average maximum TSP concentration during non-working hours) + Background

3.5.10 Appendix 3.2 shows the calculation of the dust emission factors and Appendix 3.3 provides sample computer outputs from the FDM model used for the construction dust impact assessment.

3.5.11 Potential air quality impact during the operational phase of the CWB & IECL is likely to arise from the following pollutant sources:

· background pollutant levels within and adjacent to the CWB & IECL as described in Section 3.3;

· vehicle emissions from open sections of existing and planned road networks;

· tunnel portal and ventilation building emissions from the CWB & IECL;

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

· portal emissions from the existing underpasses along Connaught Road Central; and

· portal emissions from the planned deckovers along Road P1, Road P2 and Connaught Road Central.

Vehicle Emissions from Open Sections of Existing and Planned Road Networks

3.5.12 The CALINE4 dispersion model was used for calculation of the 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO concentrations. Open sections of existing and planned road networks within 500 m from the boundary of the CWB & IECL are considered in the model and are listed as follows:

· the CWB & IECL;

· new roads in the Wan Chai Development Phase II (WDII);

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

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

3.5.13 The predicted morning peak hour traffic flows and vehicle mixes for the road networks in 2027 were used for the assessment of the worst-case air quality scenario. Figures 3.3.1 to 3.3.6 show the projected 2027 morning peak hour traffic flows and vehicle compositions.

3.5.14 The most up-to-date vehicular emission factors (Fleet Average Emission Factors – EURO3 Model) available from the EPD are for the year 2011 and these were adopted for the assessment. It is, however, considered that the 2027 emission rates will be lower than those of 2011, as more stringent vehicle emission control will have been in place by that time. The predicted results will therefore be conservative.

3.5.15 The composite emission factors for the road links were calculated as the weighted average of the emission factors of different types of vehicles. Four vehicle categories have been adopted. As a worst-case scenario, the maximum emission factor within the same category was used for the assessment. The vehicular emissions for different vehicle categories are listed in Table 3.7. Detailed calculations of the emission factors are shown in Appendix 3.4.

Table 3.7 Emission Factors for Year 2011 for Different Vehicle Categories (EURO3)

Pollutant	Emission Factors for 2011 (EURO3), g/km-veh
Pollutant	PV ⁽¹⁾	LGV ⁽²⁾	HGV ⁽³⁾	PT ⁽⁴⁾
NOx	0.73	1.53	3.84	6.8
RSP	0.03	0.16	0.53	0.69
CO	1.87	2.25	6.45	7.38

Note: (1) Private Vehicles (PV) include taxi and private car.

(2) Light Goods Vehicles (LGV) include passenger van and light goods vehicle.

(3) HGV stands for Heavy Goods Vehicles.

(4) Public Transport (PT) includes all types of buses.

3.5.16 Peak hour traffic flows within and adjacent to the CWB & IECL will occur during daytime. The night time traffic flows will be low (about 10% of peak flow) and the worst-case scenario will therefore not be encountered during night time.

3.5.17 In order to calculate the cumulative pollutant concentrations from different sources using different models (CALINE4 and ISCST3) in the later part of the assessment, the dispersion modelling was undertaken assuming 360 predetermined meteorological conditions and the highest predicted pollutant concentration amongst the 360 wind directions were identified. The following summarises the meteorological conditions adopted in the air quality modelling using the CALINE4 model:

· Wind speed : 1 m s^-1

· Wind direction : 360 wind directions

· Resolution : 1°

· Wind variability : 24°

· Stability class : D

· Surface roughness : 1 m

· Mixing height : 500 m

3.5.18 The CALINE4 model calculates hourly concentrations only. With reference to the Screening Procedures for Estimating the Air Quality Impact of Stationary Source (EPA-454/R-92-019), a conversion factor of 0.4 is used to convert the 1-hour average concentrations to 24-hour average concentrations.

3.5.19 Potential air quality impacts from the implementation of proposed roadside noise barriers along the CWB & IECL were also incorporated into the air quality model. According to the findings in Section 4, semi-enclosure, cantilever barrier and vertical barrier have been proposed on the Trunk Road to mitigate the noise impacts at Causeway Bay. With the barriers in place, pollutants will tend to accumulate and disperse at a higher elevation (immediate above the barrier height).

3.5.20 Appendix 3.5 shows the sample computer outputs from the CALINE4 model used for the vehicle emissions impact assessment.

Portal and Ventilation Building Emissions

3.5.21 The Industrial Source Complex Short Term (ISCST3) dispersion model was used to predict the portal and ventilation building emissions.

3.5.22 The followings are the portal and ventilation building emissions in and around the study area:

· tunnel portal and ventilation building emissions from the tunnel section of the CWB & IECL;

· tunnel emissions from the existing CHT;

· portal emissions from the existing underpasses along Connaught Road Central; and

· portal emissions from the planned deckovers on Road P1, Road P2 and Connaught Road Central.

3.5.23 The configuration of the tunnel section of the CWB & IECL consists of:

· CWB Tunnel;

· Wanchai Bypass Tunnel; and

· Slip Road F Tunnel.

3.5.24 Vehicle emissions accumulated inside the tunnel sections are required to be extracted or diluted. In order to reduce the potential impacts from the portal emissions, three ventilation buildings have been proposed for the CWB to discharge the tunnel vitiated air:

· West Ventilation Building (WVB): for extracting vitiated tunnel air from Trunk Road Westbound;

· Central Ventilation Building (CVB): for extracting vitiated tunnel air from Slip Road F and Wanchai Bypass Westbound; and

· East Ventilation Building (EVB): for extracting vitiated tunnel air from Trunk Road Eastbound and Wanchai Bypass Eastbound.

3.5.25 Locations of the portals and ventilation buildings emissions are shown in Figures 3.4.1 and 3.4.2. The proposed portal and ventilation building emissions provided by the ventilation design engineer are summarised in Table 3.8.

Table 3.8 Portal and Ventilation Building Emissions

Type	Emission Rate (g s^-1)
Type	NO₂*	CO	RSP
Portal Emission
Trunk Road Eastbound	0	0	0
Wanchai Bypass Eastbound	0.02050	0.90250	0.00725
Slip Road F	0	0	0
Wanchai Bypass Westbound	0.09225	4.47750	0.02602
Trunk Road Westbound	0.11750	4.60500	0.03819
Ventilation Building Emission
EVB - Trunk Road Eastbound	0.84271	18.14583	0.26674
EVB - Wanchai Bypass Eastbound	0.05668	2.49515	0.02176
CVB - Slip Road F	0.12222	2.35556	0.01092
CVB – Wanchai Bypass Westbound	0.04884	2.37044	0.00867
WVB – Trunk Road Westbound	0.38364	14.23364	0.11457

Note: * Based on 20% NO₂/NO_x conversion in ambient condition.

3.5.26 The preliminary design of the ventilation buildings (including minimum discharge heights, exhaust directions, handling capacity of ventilation buildings and exit velocity) is summarised in Table 3.9. For a worse case scenario in air quality assessment, the minimum height of stack was used in modelling.

Table 3.9 Design of Ventilation Buildings

	Maximum capacity (m³ s^-1)	Exit velocity (m s^-1)	Minimum discharge height (meter above ground)	Exhaust direction
EVB - Trunk Road Eastbound	570	8	25	vertical
EVB - Wanchai Bypass Eastbound	200	8	25	vertical
CVB - Slip Road F	180	8	15	vertical
CVB - Wanchai Bypass Westbound	100	8	15	vertical
WVB - Trunk Road Westbound	420	8	15	vertical

3.5.27 The portal emissions (NO₂, RSP and CO) of the existing CHT, the existing underpasses and the planned deckover are calculated based on the vehicle emissions (EURO3) and vehicle flows in 2027. Appendix 3.6 shows the calculations of portal emissions.

3.5.28 Portal emissions were modelled in accordance with the Permanent International Association of Road Congress Report (PIARC, 1991). Pollutants were assumed to eject from the portal as a portal jet such that 2/3 of the total emissions was dispersed within the first 50 m of the portal and 1/3 of the total emissions within the second 50 m.

3.5.29 As mentioned in Section 3.5.17, 360 predetermined meteorological conditions were used. The following summarises the meteorological conditions adopted in the air quality modelling using the ISCST3 model:

· Wind speed : 1 m s^-1

· Wind direction : 360 wind directions

· Resolution : 1°

· Stability class : D

· Mixing height : 500 m

· Emission temperature : 7° above ambient

3.5.30 Sample computer output is shown in Appendix 3.7.

Model Adjustment

3.5.31 As discussed in “Technical Note on Model Calibration for Cross Harbour Tunnel and Its Nearby Roads”⁽[1]⁾, NO₂/NO_x ratio varies from the CHT portal to sensitive receivers along Gloucester Road. As a result, different NO₂/NO_x ratios were adopted in the vicinity of the CHT. Near the CHT portal, the NO₂/NO_x ratio was based on the measured values. For those far away from the portal, a more conservative value of 0.2 was used. To summarise, the following factors were used:

NO₂ /NO_x for section of Gloucester Road : 0.13

between Tonnochy Road and IECL

NO₂/NO_x for local roads near CHT : 0.13

NO₂/NO_x for other roads : 0.2

NO₂/NO_x for portal emissions of other tunnels : 0.2

and ventilation buildings

3.5.32 The spatial distribution of the NO₂/NO_x due to CHT portal emissions in the vicinity of the CHT was found to be:

(NO₂/NO_x) = 0.948 ´ 10^-4 ´ (Distance from Portal in metre) + 0.0957

3.5.33 According to on-site measurements in early 2001⁽[2]⁾, the concentration of NO₂ inside the tennis court of the Police Officers Club was far lower than that at the roadside of the Police Officers Club. The observed discrepancy was attributed to the presence of the boundary wall near the portal and the use of tarpaulin along the site boundary of the Police Officers Club, which together provide a physical barrier restricting the dispersion of pollutants into the tennis court. Besides, as the CHT is located very close to the seafront, sea breeze is expected to play an important role in diluting the pollutants. Therefore, appropriate dilution factor has been applied to the modelling result to reflect the situation.

3.5.34 Other locations towards the seaward side of the CHT, e.g. Yacht Club and the planned hotel site, are expected to be similarly screened by the boundary wall of the tunnel and influenced by sea breeze in the daytime. As discussed in “Technical Note on Model Calibration for Cross Harbour Tunnel and its Nearby Roads”, the dilution factors at Yacht club (A50), Police Officers’ Club (A51-A53), Planned Hotel site (A87, A88) are likey to be lower or similar to that at the tennis court. As a conservative estimate, a dilution factor of 0.56 was applied to all those receivers in the vicinity of the CHT.

3.5.35 The effect of the boundary wall near the tunnel portal on the dilution factor will diminish with increasing height. In this respect, a dilution factor of 0.56 will be applied to those ASRs below 10m. For those ASRs above 10m, no dilution factor is applied to the modelling result.

Cumulative Impact

3.5.36 As mentioned in Section 3.5.11, background pollutant levels within and adjacent to the CWB & IECL, vehicle emissions from open section of existing and planned road networks, tunnel portal and ventilation building emissions from the CWB & IECL, portal emissions from the CHT, the existing underpasses and the planned deckovers will all contribute to the cumulative impact.

3.5.37 The pollutant concentrations at the ASRs at different wind directions (1 degree resolution) were predicted by both CALINE4 and ISCST3 models, where

· the CALINE4 model was used to predict the open road emission from the existing and planned road networks; and

· the ISCST3 model was used to predict all the portal emissions (CWB & IECL, CHT, underpasses and deck-over) and ventilation shaft emissions.

3.5.38 The cumulative pollutant concentrations at the ASRs at each specific wind direction are calculated by summing the results from the two models. The highest pollutant concentrations at the ASRs amongst the 360 wind directions were identified as the worst predicted cumulative pollutant concentrations.

3.6 Identification of Environmental Impacts

Construction Phase

3.6.1 Potential dust nuisance will be the major concern from the construction of CWB & IECL. Public fill has been proposed for use in the reclamation works in WDII area. Major dust generating activities on site will be ground excavation, material handling, truck haulage on unpaved road and building construction. However, no on-site concrete batching activity will be taken place within the construction site.

3.6.2 The tunnel section of the CWB & IECL will be constructed by diaphragm wall method on the reclaimed land. The excavated rate of material is small and the stockpiling of material is not expected. However, as a worst-case scenario, dust nuisance is expected during excavation and backfilling of the tunnel construction.

3.6.3 The reclamations and road works by the Territory Development Department (TDD) for the CRIII and the WDII were also taken into account in assessing the impacts.

Operational Phase

3.6.4 The major sources of traffic emissions include the open road sections and various tunnel portals / ventilation shafts.

3.6.5 As mentioned in Section 3.5.11, potential air quality impact during the operational phase of the CWB & IECL includes the following pollutant sources:

· background pollutant levels within and adjacent to the CWB & IECL as described in Section 3.3;

· vehicle emissions from the open sections of existing and planned road networks;

· tunnel portal and ventilation building emissions from the tunnel section of the CWB & IECL;

· tunnel portal emissions from the existing CHT;

· portal emissions from the existing underpasses along Connaught Road Central; and

· portal emissions from the planned deckovers along Road P1, Road P2 and Connaught Road Central.

3.6.6 Air quality impacts associated with road traffic are caused mostly by NO₂, RSP and CO. The 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO were calculated and compared with the AQO limits.

3.7 Prediction and Evaluation of Environmental Impacts

Construction Phase

3.7.1 Construction activities for CWB & IECL, WDII and CRIII will cause a cumulative impact on the nearby sensitive receivers.

3.7.2 Since most of the construction activities are at ground level, the likely cumulative dust impacts of the CWB & IECL on the ASRs at 1.5 m above ground were modelled. Detailed breakdown of the dust impacts from different construction activities is shown in Appendix 3.8.

3.7.3 The cumulative 1-hour TSP and 24-hour TSP due to the construction of CWB & IECL is shown in Table 3.10 and Table 3.11.

Table 3.10 Predicted Cumulative 1-hour Average TSP Concentration for Scenarios 1 to 10 (Unmitigated)

ASR	Predicted Concentration (mg m^-3) under different scenarios *
ASR	Scen. 1	Scen. 2	Scen. 3	Scen. 4	Scen. 5	Scen. 6	Scen. 7	Scen. 8	Scen. 9	Scen. 10	Max.
A1	145	321	339	189	557	229	289	150	113	98	557
A2	147	324	345	186	618	239	309	157	113	98	618
A3	149	339	360	190	742	249	322	165	114	99	742
A4	153	369	394	197	607	267	347	179	116	100	607
A5	155	405	433	210	734	295	375	206	118	100	734
A6	182	532	591	238	446	341	439	236	127	101	591
A7	195	568	637	255	448	333	433	224	130	100	637
A8	220	649	728	284	501	364	466	249	134	100	728
A9	578	922	1006	424	624	376	464	246	143	102	1006
A10	629	722	780	345	510	327	438	211	136	104	780
A11	289	845	906	385	605	366	487	238	140	106	906
A12	290	763	807	340	537	356	472	217	140	107	807
A13	241	788	882	332	496	398	494	227	153	109	882
A14	264	932	1039	360	594	421	502	226	162	112	1039
A15	354	2582	2668	851	1310	445	587	245	168	113	2668
A16	276	1046	1153	401	696	436	537	242	163	112	1153
A17	292	1124	1251	382	608	445	554	235	170	115	1251
A18	326	1318	1457	389	556	448	589	218	178	116	1457
A19	336	1382	1501	395	539	480	595	219	195	116	1501
A20	556	2134	2307	585	998	570	653	257	213	121	2307
A21	350	1915	2056	443	729	465	556	220	184	118	2056
A22	324	975	1185	375	517	417	584	193	178	128	1185
A23	296	762	930	326	452	429	583	203	180	119	930
A24	326	578	824	337	515	526	731	229	218	113	824
A25	365	550	980	398	525	532	978	232	256	122	980
A26	436	578	1296	494	647	793	1282	320	390	167	1296
A27	391	607	1339	517	808	923	1529	358	414	168	1529
A28	506	731	1337	479	700	936	918	340	285	151	1337
A29	595	712	1802	639	822	1326	1561	424	552	191	1802
A30	406	616	1732	629	813	1100	1715	394	576	175	1732
A31	390	623	1384	534	904	875	1728	321	405	151	1728
A32	508	699	2773	938	1746	1251	1862	562	582	189	2773
A33	393	677	2513	880	1033	1170	2738	412	613	270	2738
A34	337	548	1593	721	1680	1043	3371	463	503	166	3371
A35	692	810	1783	665	1189	1041	1622	448	463	190	1783
A36	593	708	1280	531	993	960	1087	355	295	219	1280
A37	1466	1522	1937	908	1743	1842	1613	616	427	274	1937
A38	1509	1550	1026	982	1853	1908	1470	726	391	360	1908
A39	1401	2550	943	907	1443	1963	1310	736	340	450	2550
A40	535	655	819	455	710	682	669	277	223	192	819
A41	608	664	559	502	650	758	678	305	231	199	758
A42	465	773	580	495	658	825	763	310	242	203	825
A43	443	836	582	534	646	996	997	312	259	209	997
A44	327	816	614	634	617	1171	1175	293	248	226	1175
A45	372	704	714	710	880	1243	1348	239	270	253	1348
A46	404	661	869	864	921	1311	1418	234	291	265	1418
A47	434	659	1014	1008	733	1237	1333	218	303	262	1333
A48	478	604	1045	1045	895	1201	1243	161	304	272	1243
A49	540	590	1033	1036	1023	1224	1244	139	305	279	1244
A50	292	2973	703	701	829	1850	2109	376	287	616	2973
A51	507	1419	642	634	739	2252	2452	357	273	364	2452
A52	390	974	755	752	780	1635	1751	269	268	290	1751
A53	354	1124	684	675	994	2402	2567	322	289	389	2567
A54	3022	3041	1554	1556	888	403	423	106	433	172	3041
A55	1301	1309	1151	1151	353	291	302	101	448	134	1309
A56	813	820	683	682	431	254	271	99	250	125	820
A57	823	835	949	949	291	254	268	99	340	124	949
A58	883	890	641	642	322	284	296	101	225	134	890
A59	918	926	634	616	373	280	295	102	321	134	926
A60	1127	1156	1909	1895	844	500	500	102	285	196	1909
A61	1453	1557	992	976	848	559	562	109	276	226	1557
A62	883	1027	575	570	533	440	438	112	215	194	1027
A63	1045	1190	507	516	323	281	295	126	382	145	1190
A64	586	672	422	432	259	261	271	124	382	130	672
A65	459	485	366	377	236	245	251	123	393	120	485
A66	1557	1647	2258	2247	1057	590	587	104	298	232	2258

Note: * Background concentration is included.

Bold letters indicate the exceedance of AQO.

Table 3.11 Predicted Cumulative 24-hour Average TSP Concentration for Scenarios 1 to 10 (Unmitigated)

ASR	Predicted Concentration (mg m^-3) *
ASR	Scen. 1	Scen. 2	Scen. 3	Scen. 4	Scen. 5	Scen. 6	Scen. 7	Scen. 8	Scen. 9	Scen. 10	Max.
A1	114	205	215	136	328	157	187	117	98	90	328
A2	115	206	218	135	361	162	198	120	98	90	361
A3	116	213	226	137	427	167	204	124	99	90	427
A4	118	229	243	141	356	176	217	132	100	91	356
A5	119	248	263	147	428	191	231	145	101	91	428
A6	133	313	344	162	268	215	264	161	106	91	344
A7	139	331	366	171	269	211	261	155	107	91	366
A8	152	373	412	186	296	226	278	167	109	91	412
A9	331	513	555	257	361	233	278	167	114	92	555
A10	356	411	439	216	302	208	264	149	111	93	439
A11	187	474	503	237	350	228	289	162	113	94	503
A12	188	431	452	214	315	223	281	152	113	94	452
A13	163	443	489	210	295	244	293	156	120	96	489
A14	175	516	569	224	345	256	297	156	125	97	569
A15	221	1348	1388	472	706	268	340	166	128	98	1388
A16	181	574	626	245	397	264	314	164	125	97	626
A17	189	612	676	235	352	268	323	161	129	99	676
A18	207	710	781	239	325	270	341	152	133	99	781
A19	212	741	804	242	316	286	344	152	142	99	804
A20	323	1125	1212	339	547	332	374	172	152	102	1212
A21	219	1009	1081	266	412	278	324	153	136	100	1081
A22	206	537	646	231	304	254	338	139	133	105	646
A23	192	429	517	207	271	259	337	144	134	101	517
A24	207	337	466	213	303	309	412	158	155	98	466
A25	228	324	544	244	308	314	536	160	176	102	544
A26	268	343	713	294	371	449	691	206	248	126	713
A27	245	355	730	305	451	511	819	225	260	126	819
A28	301	418	735	285	396	515	508	215	190	117	735
A29	353	415	984	367	458	720	832	260	335	138	984
A30	255	363	933	363	455	605	913	244	346	130	933
A31	244	363	752	314	500	487	918	206	254	118	918
A32	301	398	1458	533	930	684	992	332	344	137	1458
A33	256	400	1324	494	566	636	1435	254	364	180	1435
A34	234	342	857	412	892	579	1753	281	310	125	1753
A35	391	452	949	384	650	576	868	274	283	138	949
A36	341	400	693	313	547	531	596	224	196	152	693
A37	783	812	1026	506	934	984	871	361	266	182	1026
A38	810	831	572	546	985	1020	796	417	254	226	1020
A39	754	1329	530	508	776	1046	716	424	231	274	1329
A40	312	373	459	273	402	389	383	184	160	139	459
A41	348	379	328	296	372	429	388	199	165	143	429
A42	277	434	338	292	376	462	431	201	170	145	462
A43	265	466	339	312	370	548	551	202	179	148	551
A44	207	456	355	363	354	641	646	192	174	157	646
A45	228	399	405	402	487	684	739	163	185	171	739
A46	245	377	483	479	508	719	776	161	196	177	776
A47	260	377	556	552	414	677	728	152	202	175	728
A48	282	350	573	572	496	657	681	123	204	179	681
A49	314	344	567	567	560	665	678	112	206	183	678
A50	190	1555	401	398	463	983	1119	235	199	361	1555
A51	297	763	369	364	417	1185	1290	226	188	230	1290
A52	238	536	426	423	438	881	943	180	185	191	943
A53	221	614	391	385	546	1280	1366	206	196	242	1366
A54	1563	1579	837	836	502	252	264	95	277	130	1579
A55	704	709	631	630	231	193	200	92	287	110	709
A56	454	459	391	390	264	173	183	91	175	105	459
A57	460	467	525	524	195	173	181	91	221	105	525
A58	491	496	372	372	212	188	196	92	167	109	496
A59	510	518	373	363	241	187	195	93	217	110	518
A60	619	644	1020	1012	489	297	299	92	194	141	1020
A61	781	839	557	548	487	326	330	96	192	155	839
A62	488	564	340	336	318	266	266	97	157	139	564
A63	570	647	306	310	214	185	193	104	252	114	647
A64	338	385	261	266	179	174	181	104	252	107	385
A65	274	291	232	236	167	167	171	103	257	102	291
A66	842	896	1203	1196	603	342	343	94	204	159	1203

Note: * Background concentration is included.

Bold letters indicate the exceedance of AQO.

3.7.4 As shown in Tables 3.10 and 3.11, exceedances of both 1-hour and 24-hour TSP objectives are predicted at almost all ASRs, except A65 in different scenarios. Maximum predicted 1-hour and 24-hour TSP at the HKCEC Extension (A34) in Scenario 7 are 3,371 mg m^-3 and 1,753 mg m^-3, respectively.

3.7.5 Since exceedance of both TSP guideline and AQO is predicted at most of the ASR locations, dust suppression measures are required.

Operational Phase

3.7.6 Taking into account the vehicle emissions from open road networks, portal and ventilation building emissions from the CWB & IECL, portal emissions from the CHT, existing underpasses and planned deckovers, and the background pollutant concentrations, the cumulative 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO concentrations at 360 wind directions were predicted and the highest pollutant concentrations at each ASR under the worst wind directions were calculated.

3.7.7 In order to determine the likely impacts on upper level receivers, pollutant concentrations at various levels (1.5 m to 150 m above ground) have been calculated. All the results are shown in Appendix 3.9.

3.7.8 From the results, it is clear that the maximum pollutant concentrations would occur at 1.5 m above ground. Table 3.12 summaries the predicted cumulative 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO concentrations at 1.5 m above ground.

Table 3.12 Predicted Cumulative 1-hour Average NO₂, 24-hour Average NO₂, 24-hour Average RSP and 1-hour Average CO Concentrations at the Representative ASRs at 1.5 m above ground

	Predicted Concentration (mg m^-3) *
ASR	1-Hour NO₂	24-Hour NO₂	24-Hour RSP	1-Hour CO
A1	226	124	83	2757
A2	249	133	85	3242
A3	254	135	86	3283
A4	208	117	79	2666
A5	201	114	78	2602
A6	212	118	80	2718
A7	237	128	84	2998
A8	264	139	89	3076
A9	153	95	71	2004
A10	192	110	77	2324
A11	144	91	69	1902
A12	196	112	76	2401
A13	234	127	82	2892
A14	278	145	90	3234
A15	126	84	64	1989
A16	254	135	86	2943
A17	277	144	90	3235
A18	241	130	83	3025
A19	264	139	87	3090
A20	127	84	64	2020
A21	205	116	77	2520
A22	246	132	84	3014
A23	272	142	88	3293
A24	248	133	85	2997
A25	245	131	85	2914
A26	153	95	69	2162
A27	179	105	72	2386
A28	138	89	65	2225
A29	134	87	65	2091
A30	138	89	66	2457
A31	143	91	67	2620
A32	182	106	69	5728
A33	131	86	64	3053
A34	129	85	63	3089
A35	137	89	66	2881
A36	180	106	74	2616
A37	156	96	70	2136
A38	165	99	77	2338
A39	154	95	76	2277
A40	213	119	90	3272
A41	196	112	86	2995
A42	207	116	89	3119
A43	232	127	100	3295
A44	265	140	111	3934
A45	263	139	111	3969
A46	253	135	108	3817
A47	228	125	98	3364
A48	205	115	88	2964
A49	202	114	86	2890
A50	193	111	94	3089
A51	244	131	109	3762
A52	174	103	88	2811
A53	231	126	108	3709
A54	192	110	77	2494
A55	167	101	73	2272
A56	160	98	71	2220
A57	186	108	76	2457
A58	186	108	76	2440
A59	218	121	82	2745
A60	205	115	80	2640
A61	206	116	80	2601
A62	168	101	73	2254
A63	187	108	77	2416
A64	184	107	76	2400
A65	188	109	77	2444
A66	193	111	78	2486
A67	147	92	67	3386
A68	225	124	77	6621
A69	136	88	68	2399
A70	135	88	65	2049
A71	166	100	71	2196
A72	158	97	69	2407
A73	147	92	67	2186
A74	131	86	64	1939
A75	125	83	64	1820
A76	141	90	67	2435
A77	167	100	70	3022
A78	137	89	66	2500
A79	114	79	62	2232
A80	129	85	66	2132
A81	145	92	68	2776
A82	156	96	71	2247
A83	162	98	72	2227
A84	206	116	79	2944
A85	194	111	77	2425
A86	184	107	76	2365
A87	291	150	130	4732
A88	156	96	83	2579
A89	134	87	67	1912
A90	234	127	85	2860

Note: * Background concentrations are included.

3.7.9 From the above table, it is noted that the predicted 24-hour NO₂ concentration at ASR A87 (planned hotel / commercial building) at 1.5m above ground approaches the AQO. However, as the proposed development will be central air-conditioned with fresh air intakes at high level, the air quality at A87 is considered acceptable.

3.7.10 Based on the above prediction, no exceedance of 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO objective would occur at any ASR in the Study Area. Mitigation measures are therefore not required.

3.7.11 The predicted cumulative maximum 1-hour NO₂ concentrations at 1.5 m, 10 m, 20 m, 30 m, 70 m and 110 m above ground are shown in Figures 3.5.1 to 3.10.4. The maximum predicted cumulative 24-hour NO₂, 24-hour RSP and 1-hour CO concentrations contour plots at 1.5 m above ground are shown in Figures 3.11.1 to 3.13.4.

3.8 Mitigation of Adverse Environmental Impacts

Construction Phase

3.8.1 As shown in Tables 3.10 and 3.11, the cumulative 1-hour and 24-hour TSP concentrations are predicted to exceed the TSP criteria at almost all of the ASRs. In order to minimize the air quality impact during the construction, the following mitigation measures for the CWB & IECL project are proposed:

CWB & IECL project (excluding works entrusted to TDD), managed by HyD

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition. This will reduce the dust generation by about 90%, in accordance with Control Techniques for Particulate Emissions from Stationary Sources, Volume 2, US Environmental Protection Agency 1982;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry. Through the implementation of this mitigation measure, dust emissions from materials handling can be reduced by 50%, according to USEPA AP-42;

Ÿ watering during excavation and material handling; this can reduce the emission by 85%;

· provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

· tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

CWB entrusted works, managed by TDD under WDII project

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ watering during excavation and material handling;

Ÿ provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

Ÿ tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

CWB entrusted works, managed by TDD under CRIII project

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ watering during excavation and material handling;

· provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

· tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

3.8.2 In addition, the following mitigation measures proposed in WDII and CRIII projects are assumed to be implemented by all relevant parties.

WDII (non-CWB entrusted work), managed by TDD

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ watering during excavation and material handling;

· provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

· tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

CRIII (non-CWB entrusted work), managed by TDD

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ watering during excavation and material handling;

· provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

· tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

3.8.3 With the above mitigation measures, the predicted cumulative 1-hour and 24-hour TSP concentrations are shown in Tables 3.13 and 3.14. The maximum predicted cumulative 1-hour and 24-hour TSP concentrations within the whole construction period are shown in Figures 3.14.1 to 3.15.4. Detailed breakdown of the dust impacts from different construction activities is shown in Appendix 3.10.

Table 3.13 Predicted Cumulative 1-hour Average TSP Concentration for Scenarios 1 to 10 (Mitigated)

ASR	Predicted Concentration (mg m^-3) under different scenarios *
ASR	Scen. 1	Scen. 2	Scen. 3	Scen. 4	Scen. 5	Scen. 6	Scen. 7	Scen. 8	Scen. 9	Scen. 10	Max.
A1	88	107	108	94	259	116	123	107	88	89	259
A2	88	107	109	93	287	120	127	111	88	89	287
A3	89	109	111	94	347	124	131	114	88	90	347
A4	89	112	114	95	273	131	139	121	88	90	273
A5	89	116	118	96	331	144	152	134	88	90	331
A6	93	130	136	99	167	157	167	145	90	90	167
A7	95	134	141	101	163	151	161	139	91	90	163
A8	98	144	151	104	176	163	174	150	91	90	176
A9	154	173	181	119	185	160	170	146	93	91	185
A10	161	150	155	110	162	143	154	129	92	92	162
A11	110	163	168	114	180	156	169	142	92	93	180
A12	111	154	157	109	168	148	160	133	92	93	168
A13	99	156	165	109	162	151	161	132	94	93	165
A14	102	171	180	112	170	151	159	129	95	94	180
A15	111	341	348	160	257	160	174	137	96	96	348
A16	103	183	193	116	188	158	168	136	95	94	193
A17	104	191	202	114	175	155	166	132	97	95	202
A18	108	210	223	116	159	146	161	121	98	95	223
A19	110	217	227	117	153	145	156	116	101	95	227
A20	132	296	311	135	209	158	167	124	103	98	311
A21	111	271	283	122	180	146	154	119	99	96	283
A22	107	175	195	114	149	132	149	107	99	101	195
A23	104	152	169	109	141	132	147	107	99	99	169
A24	106	133	159	110	143	140	160	108	103	97	160
A25	110	131	175	120	141	139	184	106	108	99	184
A26	118	134	207	132	157	169	217	117	126	107	217
A27	114	137	212	133	174	181	248	121	130	106	248
A28	127	152	211	131	165	183	180	120	114	108	211
A29	137	150	259	154	179	229	248	130	150	112	259
A30	115	138	253	151	176	203	263	126	150	111	263
A31	114	139	217	135	184	175	273	117	128	109	273
A32	127	147	365	183	268	214	271	141	150	135	365
A33	117	144	336	185	195	205	386	126	156	119	386
A34	114	132	242	155	263	198	394	134	141	124	394
A35	146	159	261	150	207	190	254	128	135	135	261
A36	136	148	208	133	185	180	195	116	121	150	208
A37	229	235	279	173	277	278	257	147	137	177	279
A38	235	240	185	181	280	286	242	161	138	220	286
A39	223	339	176	173	235	293	226	162	132	266	339
A40	130	142	160	124	154	149	148	106	115	137	160
A41	138	144	133	128	146	158	149	109	121	140	158
A42	122	155	134	127	147	165	158	110	124	142	165
A43	120	162	136	131	147	185	185	111	129	145	185
A44	108	161	139	142	144	206	207	109	135	153	207
A45	112	149	150	150	171	218	230	102	146	167	230
A46	115	144	166	166	176	224	237	102	156	173	237
A47	119	143	181	181	155	215	226	100	163	171	226
A48	123	138	185	185	172	204	208	92	168	176	208
A49	130	139	184	184	185	208	210	90	171	180	210
A50	103	391	149	149	166	273	302	117	139	348	391
A51	127	224	141	140	159	314	338	117	136	222	338
A52	115	177	154	154	164	263	276	106	142	185	276
A53	111	193	147	146	186	338	357	112	141	235	357
A54	384	389	239	239	171	119	121	85	249	126	389
A55	213	214	195	195	118	105	107	84	258	107	258
A56	159	160	147	147	122	101	103	84	160	103	160
A57	162	164	174	174	110	101	103	84	204	103	204
A58	169	170	147	147	112	104	106	84	147	107	170
A59	170	171	143	142	117	104	106	84	194	107	194
A60	189	207	282	281	178	129	129	84	176	138	282
A61	223	244	187	186	176	135	136	85	171	153	244
A62	166	183	136	136	136	122	122	85	140	138	183
A63	181	197	129	130	111	104	106	87	217	113	217
A64	135	143	119	120	104	102	103	87	216	105	216
A65	121	125	113	114	101	100	101	87	222	101	222
A66	234	260	321	320	204	139	139	84	182	156	321

Note: * Background concentration is included.

Table 3.14 Predicted Cumulative 24-hour Average TSP Concentration for Scenarios 1 to 10 (Mitigated)

ASR	Predicted Concentration (mg m^-3) *
ASR	Scen. 1	Scen. 2	Scen. 3	Scen. 4	Scen. 5	Scen. 6	Scen. 7	Scen. 8	Scen. 9	Scen. 10	Max.
A1	85	96	97	88	175	100	103	95	85	85	175
A2	85	96	97	88	190	101	105	96	85	85	190
A3	85	97	98	88	222	103	107	98	85	85	222
A4	85	99	100	89	183	107	112	102	85	86	183
A5	85	101	103	90	216	114	118	108	85	86	216
A6	88	109	112	91	126	121	126	114	86	86	126
A7	89	111	114	92	125	118	123	111	87	86	125
A8	90	116	120	94	131	124	129	117	87	86	131
A9	118	133	136	102	137	123	128	115	88	86	137
A10	122	120	122	97	124	114	120	107	87	87	124
A11	97	127	129	99	134	121	127	113	88	87	134
A12	97	122	123	97	127	117	123	108	88	87	127
A13	91	123	127	96	125	118	124	108	89	87	127
A14	93	131	135	98	129	118	123	106	90	88	135
A15	97	219	221	124	174	123	131	111	91	89	221
A16	93	137	141	100	139	122	127	110	90	88	141
A17	94	141	147	100	131	120	126	108	91	88	147
A18	96	151	158	100	123	116	124	102	92	88	158
A19	97	154	160	101	120	116	121	100	93	88	160
A20	109	197	205	111	149	123	127	104	94	90	205
A21	97	182	188	104	134	116	121	101	92	89	188
A22	96	132	145	100	118	109	117	95	92	91	145
A23	94	120	131	97	113	109	117	95	92	90	131
A24	96	111	126	97	114	113	123	96	95	89	126
A25	98	110	135	103	114	113	136	95	98	91	136
A26	104	114	156	110	122	131	154	102	110	95	156
A27	102	115	157	110	131	136	171	104	111	94	171
A28	107	122	159	108	126	136	135	103	101	95	159
A29	116	124	191	121	133	163	170	109	125	97	191
A30	104	117	181	120	132	150	179	107	124	97	181
A31	102	115	159	112	136	133	184	101	110	96	184
A32	107	118	238	144	183	157	186	116	122	109	238
A33	108	123	222	140	143	148	246	107	127	102	246
A34	110	120	170	123	178	148	251	112	120	103	251
A35	116	123	179	121	151	143	176	109	114	109	179
A36	111	117	151	111	138	136	144	102	105	117	151
A37	160	163	189	133	190	190	181	120	115	131	190
A38	165	168	143	139	190	196	172	128	118	154	196
A39	159	217	138	134	165	199	163	129	116	177	217
A40	108	114	125	105	121	119	118	96	102	110	125
A41	112	116	111	107	117	124	120	98	105	112	124
A42	104	121	112	106	117	128	124	98	107	113	128
A43	102	125	112	109	117	138	139	99	110	115	139
A44	96	124	114	114	115	151	153	97	113	119	153
A45	97	118	119	119	130	160	168	93	118	126	168
A46	99	115	128	127	132	164	172	93	123	129	172
A47	101	115	136	135	122	157	164	92	127	128	164
A48	103	113	138	137	130	150	154	88	130	130	154
A49	107	114	137	137	137	151	153	86	132	132	153
A50	94	250	119	119	127	186	204	102	117	221	250
A51	105	159	115	114	123	207	221	102	114	155	221
A52	99	133	122	121	126	183	192	96	117	136	192
A53	97	143	118	117	138	229	240	99	117	161	240
A54	238	244	170	169	135	105	107	84	175	105	244
A55	154	154	145	145	106	97	98	83	181	95	181
A56	124	125	118	118	105	94	96	83	125	93	125
A57	126	127	132	132	100	94	95	83	148	93	148
A58	130	131	120	119	102	96	97	83	121	95	131
A59	131	133	120	118	106	96	97	83	145	95	145
A60	143	157	194	193	143	108	109	83	134	111	194
A61	159	172	145	143	140	111	113	84	133	118	172
A62	127	137	114	114	114	104	105	84	115	110	137
A63	134	144	111	111	102	95	96	84	159	97	159
A64	111	116	105	105	97	93	95	84	159	94	159
A65	103	107	101	101	95	92	93	84	162	91	162
A66	169	187	217	216	159	113	114	83	139	120	217

Note: * Background concentration is included.

3.8.4 From the above results, the predicted dust levels at all air sensitive receivers would comply with the 1-hour and 24-hour TSP criteria with the above mitigation measures.

3.8.5 To further ensure compliance with the AQOs at the ASRs at all time, requirements of the Air Pollution Control (Construction Dust) Regulation shall be adhered to during the construction period. In addition, good site practices and a comprehensive dust monitoring and audit programme are recommended to minimise cumulative dust impacts.

Operational Phase

3.8.6 The predicted air quality impacts on the ASRs are within the Air Quality Objectives. No mitigation measure will be required during the operation phase. However, as a good engineering practice, the fresh air intake for the planned hotel should be located at a high level and faced away from the CHT tunnel portal.

3.9 Evaluation of Residual Impacts

Construction Phase

3.9.1 With the recommended mitigation measures during the CWB & IECL construction, there will be no adverse residual air quality impact generated from the CWB & IECL construction activities.

Operational Phase

3.9.2 No adverse residual air quality impact is predicted.

3.10 Environmental Monitoring and Audit

Construction Phase

3.10.1 With the implementation of the proposed dust suppression measures (Sections 3.8.1 and 3.8.2), good site practices and comprehensive dust monitoring and audit, the TSP levels at all ASRs will comply with the dust criteria. Details of the monitoring requirements such as monitoring locations, frequency of baseline and impact monitoring are presented in the stand-alone EM&A Manual.

Operational Phase

3.10.2 For the air pollution within the tunnel section of the CWB & IECL, monitoring of tunnel air quality should be required to ensure the acceptability of the tunnel air quality criteria.

3.11 Conclusion

Construction Phase

3.11.1 During the construction of the CWB & IECL, ground excavation, material handling, truck haulage on unpaved road, ventilation building construction as well as tunnel construction would generate a large amount of dust. The concurrent reclamations and road works, by the TDD for the CRIII and the WDII would also generate dust impacts. Due to the complex sequencing of the activities, ten worst-case scenarios of the construction schedules were identified and modelled using the FDM model.

3.11.2 Exceedances of the TSP criteria were predicted to occur at ASRs in the vicinity during construction. In order to achieve the Air Quality Objectives, the following mitigation measures for the CWB & IECL construction are recommended:

CWB & IECL project (excluding works entrusted to TDD), managed by HyD

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ watering during excavation and material handling;

Ÿ provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

Ÿ tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

CWB entrusted works, managed by TDD under WDII project

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry.;

Ÿ watering during excavation and material handling;

Ÿ provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

Ÿ tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

CWB entrusted works, managed by TDD under CRIII project

Ÿ strictly limit the truck speed on site to below 10 km per hour and water spraying to keep the haul roads in wet condition;

Ÿ twice daily watering of the work site with active operations when the weather and the work site are dry.;

Ÿ watering during excavation and material handling;

· provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

· tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

3.11.3 With the above mitigation measures on the CWB & IECL construction, the predicted dust levels at all ASRs would comply with the 1-hour and 24-hour TSP criteria. There would be no adverse residual air quality impact due to the CWB & IECL construction activities.

Operational Phase

3.11.4 The cumulative effects arising from the background pollutant levels within and adjacent to the CWB & IECL, vehicle emissions from open road networks, tunnel portal and ventilation building emissions from the CWB & IECL, tunnel portal emissions from the CHT, and portal emissions from existing underpasses and planned deckovers was modelled using the CALINE4 and ISCST3 models.

3.11.5 Results show that the predicted air quality at the ASRs would comply with the AQOs. No mitigation measures are proposed.

3.11.6 For the air pollution within the tunnel section of the CWB & IECL, monitoring of tunnel air quality should be required to ensure the acceptability of the tunnel air quality criteria.

([1]) Maunsell Consultants Asia Ltd. (2001). Central-Wan Chai Bypass and Island Eastern Corridor Link, Design and Construction Assignment, Project Review Study, “Technical Note on Model Calibration for Cross Harbour Tunnel and Its Nearby Roads”.

([2]) Maunsell Environmental Management Consultants Ltd. (2001). “Short-term Air Quality Monitoring near Cross Harbour Tunnel”.

3.2.4 In addition, the visibility in tunnels acts as an indicator of smoke concentration and should be controlled so that extinction coefficient does not exceed 0.005 per meter (over five minutes).

3.3 Description of the Environment

3.3.2 The annual average concentrations of the pollutants were used as the background concentrations for the cumulative impact assessment.

3.4.1 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 ASRs are listed in Table 3.4 and the corresponding locations are shown in Figures 3.1.1 and 3.1.2.

3.5.4 The 1997 meteorological data from the Hong Kong Observatory (Central Station) was used in the FDM to predict the 1-hour and 24-hour averaged TSP concentrations. The data includes hourly-averaged wind speed, wind direction, stability class, ambient temperature and mixing height.

3.5.5 The following summarises the construction stages of the CWB & IECL project. The locations of different construction works are shown in Figures 3.2.1 and 3.2.2.

3.5.6 Besides the CWB & IECL project, the following is a list of interfacing projects from 2002 to 2012 within 500 m from the study boundary. The locations of different construction works are shown in Figures 3.2.1 and 3.2.2.

3.5.8 The working hours of all construction sites were assumed to be 12 hours. Truck speed within the sites was limited to 10 km per hour.

3.5.9 Daily TSP concentrations were calculated as follows:

3.5.10 Appendix 3.2 shows the calculation of the dust emission factors and Appendix 3.3 provides sample computer outputs from the FDM model used for the construction dust impact assessment.

3.5.11 Potential air quality impact during the operational phase of the CWB & IECL is likely to arise from the following pollutant sources:

3.5.13 The predicted morning peak hour traffic flows and vehicle mixes for the road networks in 2027 were used for the assessment of the worst-case air quality scenario. Figures 3.3.1 to 3.3.6 show the projected 2027 morning peak hour traffic flows and vehicle compositions.

3.5.20 Appendix 3.5 shows the sample computer outputs from the CALINE4 model used for the vehicle emissions impact assessment.

3.5.22 The followings are the portal and ventilation building emissions in and around the study area:

3.5.23 The configuration of the tunnel section of the CWB & IECL consists of:

3.5.24 Vehicle emissions accumulated inside the tunnel sections are required to be extracted or diluted. In order to reduce the potential impacts from the portal emissions, three ventilation buildings have been proposed for the CWB to discharge the tunnel vitiated air:

3.5.25 Locations of the portals and ventilation buildings emissions are shown in Figures 3.4.1 and 3.4.2. The proposed portal and ventilation building emissions provided by the ventilation design engineer are summarised in Table 3.8.

3.5.27 The portal emissions (NO2, RSP and CO) of the existing CHT, the existing underpasses and the planned deckover are calculated based on the vehicle emissions (EURO3) and vehicle flows in 2027. Appendix 3.6 shows the calculations of portal emissions.

3.5.29 As mentioned in Section 3.5.17, 360 predetermined meteorological conditions were used. The following summarises the meteorological conditions adopted in the air quality modelling using the ISCST3 model:

3.5.30 Sample computer output is shown in Appendix 3.7.

3.5.32 The spatial distribution of the NO2/NOx due to CHT portal emissions in the vicinity of the CHT was found to be:

3.5.35 The effect of the boundary wall near the tunnel portal on the dilution factor will diminish with increasing height. In this respect, a dilution factor of 0.56 will be applied to those ASRs below 10m. For those ASRs above 10m, no dilution factor is applied to the modelling result.

3.5.37 The pollutant concentrations at the ASRs at different wind directions (1 degree resolution) were predicted by both CALINE4 and ISCST3 models, where

3.6.3 The reclamations and road works by the Territory Development Department (TDD) for the CRIII and the WDII were also taken into account in assessing the impacts.

3.6.4 The major sources of traffic emissions include the open road sections and various tunnel portals / ventilation shafts.

3.6.5 As mentioned in Section 3.5.11, potential air quality impact during the operational phase of the CWB & IECL includes the following pollutant sources:

3.6.6 Air quality impacts associated with road traffic are caused mostly by NO2, RSP and CO. The 1-hour NO2, 24-hour NO2, 24-hour RSP and 1-hour CO were calculated and compared with the AQO limits.

3.7.1 Construction activities for CWB & IECL, WDII and CRIII will cause a cumulative impact on the nearby sensitive receivers.

3.7.2 Since most of the construction activities are at ground level, the likely cumulative dust impacts of the CWB & IECL on the ASRs at 1.5 m above ground were modelled. Detailed breakdown of the dust impacts from different construction activities is shown in Appendix 3.8.

3.7.3 The cumulative 1-hour TSP and 24-hour TSP due to the construction of CWB & IECL is shown in Table 3.10 and Table 3.11.

3.7.4 As shown in Tables 3.10 and 3.11, exceedances of both 1-hour and 24-hour TSP objectives are predicted at almost all ASRs, except A65 in different scenarios. Maximum predicted 1-hour and 24-hour TSP at the HKCEC Extension (A34) in Scenario 7 are 3,371 mg m-3 and 1,753 mg m-3, respectively.

3.7.5 Since exceedance of both TSP guideline and AQO is predicted at most of the ASR locations, dust suppression measures are required.

3.7.7 In order to determine the likely impacts on upper level receivers, pollutant concentrations at various levels (1.5 m to 150 m above ground) have been calculated. All the results are shown in Appendix 3.9.

3.7.8 From the results, it is clear that the maximum pollutant concentrations would occur at 1.5 m above ground. Table 3.12 summaries the predicted cumulative 1-hour NO2, 24-hour NO2, 24-hour RSP and 1-hour CO concentrations at 1.5 m above ground.

3.7.10 Based on the above prediction, no exceedance of 1-hour NO2, 24-hour NO2, 24-hour RSP and 1-hour CO objective would occur at any ASR in the Study Area. Mitigation measures are therefore not required.

3.8.2 In addition, the following mitigation measures proposed in WDII and CRIII projects are assumed to be implemented by all relevant parties.

3.8.4 From the above results, the predicted dust levels at all air sensitive receivers would comply with the 1-hour and 24-hour TSP criteria with the above mitigation measures.

Operational Phase

3.9.1 With the recommended mitigation measures during the CWB & IECL construction, there will be no adverse residual air quality impact generated from the CWB & IECL construction activities.

3.9.2 No adverse residual air quality impact is predicted.

3.10.2 For the air pollution within the tunnel section of the CWB & IECL, monitoring of tunnel air quality should be required to ensure the acceptability of the tunnel air quality criteria.

3.11.2 Exceedances of the TSP criteria were predicted to occur at ASRs in the vicinity during construction. In order to achieve the Air Quality Objectives, the following mitigation measures for the CWB & IECL construction are recommended:

3.11.3 With the above mitigation measures on the CWB & IECL construction, the predicted dust levels at all ASRs would comply with the 1-hour and 24-hour TSP criteria. There would be no adverse residual air quality impact due to the CWB & IECL construction activities.

3.11.5 Results show that the predicted air quality at the ASRs would comply with the AQOs. No mitigation measures are proposed.

3.11.6 For the air pollution within the tunnel section of the CWB & IECL, monitoring of tunnel air quality should be required to ensure the acceptability of the tunnel air quality criteria.

3.5.27 The portal emissions (NO₂, RSP and CO) of the existing CHT, the existing underpasses and the planned deckover are calculated based on the vehicle emissions (EURO3) and vehicle flows in 2027. Appendix 3.6 shows the calculations of portal emissions.

3.5.32 The spatial distribution of the NO₂/NO_x due to CHT portal emissions in the vicinity of the CHT was found to be:

3.6.6 Air quality impacts associated with road traffic are caused mostly by NO₂, RSP and CO. The 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO were calculated and compared with the AQO limits.

3.7.4 As shown in Tables 3.10 and 3.11, exceedances of both 1-hour and 24-hour TSP objectives are predicted at almost all ASRs, except A65 in different scenarios. Maximum predicted 1-hour and 24-hour TSP at the HKCEC Extension (A34) in Scenario 7 are 3,371 mg m^-3 and 1,753 mg m^-3, respectively.

3.7.8 From the results, it is clear that the maximum pollutant concentrations would occur at 1.5 m above ground. Table 3.12 summaries the predicted cumulative 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO concentrations at 1.5 m above ground.

3.7.10 Based on the above prediction, no exceedance of 1-hour NO₂, 24-hour NO₂, 24-hour RSP and 1-hour CO objective would occur at any ASR in the Study Area. Mitigation measures are therefore not required.