3. air quality

3.1 Introduction

3.1.1 Potential air quality impacts associated with the construction and operation phases of the Project are presented in this section. Representative Air Sensitive Receivers (ASRs) were identified and the potential air quality impacts on these receivers arising from construction dust emission, vehicle emission, industrial emission and emissions from flaring plant at landfill have been evaluated. Appropriate mitigation measures were proposed to alleviate the potential air quality impacts.

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 Hong Kong Air Quality Objectives (AQOs), which must be satisfied, stipulate the maximum allowable concentrations over specific period for typical pollutants. 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	-	-	-

Note:

(1) Measured at 298 K and 101.325 kPa.

(2) Not to be exceeded more than three times per year.

(3) Not to be exceeded more than once per year.

(4) Arithmetic mean.

(5) Suspended particulates in air with a nominal aerodynamic diameter of 10 mm or smaller.

(6) Photochemical oxidants are determined by measurement of ozone only.

3.2.3 The EIAO-TM stipulates that the hourly TSP level should not exceed 500 mgm^-3 (measured at 25^oC and one atmosphere) for construction dust impact assessment. Mitigation measures for construction sites have been specified in the Air Pollution Control (Construction Dust) Regulations.

3.2.4 The Practice Note on Control of Air Pollution in Vehicle Tunnel, prepared by the Environment Protection Department (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/m^3) ^(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

Study Area of Western Coast Road

3.3.1 The proposed alignment of the Western Coast Road (WCR) is from Lam Tin, via Cha Kwo Ling and Chiu Keng Wan Shan (tunnel section) to Tseung Kwan O (TKO) Town Centre South (TCS). The land uses in the vicinity of the tunnel section of the WCR are residential, commercial and industrial uses. The dominant existing emission source at the Kowloon section of the WCR is the existing traffic from the Kwun Tong Bypass and Eastern Harbour Crossing (EHC). Emissions from industries in Kwun Tong and Yau Tong also affect local air quality.

3.3.2 The EPD air quality monitoring station at Kwun Tong is located nearest to the study area of the WCR on the Kowloon side. The latest published air quality monitoring data at this station is in year 2002, but the data are insufficient to calculate annual average values. Hence, the annual average concentrations of pollutants in Year 2001 are the latest reliable data to reflect the existing condition (Table 3.3).

Table 3.3 EPD Air Quality Monitoring Data at Kwun Tong Station in 2001

Pollutant	Annual Average Concentration (μg/m^3)
SO2	15
NO2	75
Ozone	25
TSP	79
RSP	56

3.3.3 The TKO section of the WCR is in a predominantly rural area and there is no air pollution source located in the vicinity of the road.

Study Area of TKO Town Centre South

3.3.4 The study area is a newly developed area. Since EPD’s air quality monitoring station at TKO ceased operation in 1993, there is no recent air quality monitoring data available for this area. Existing air quality in the study area is affected by emissions from road traffic, landfill gas and construction activities in and around the study area.

Study Area of Cross Bay Link

3.3.5 The proposed Cross Bay Link (CBL) would connect the WCR to Area 86 in TKO. The alignment near the WCR is in a predominantly rural area with no air emission source. Near Area 86, there are emissions of various air pollutants including copper, lead, particulates, SO₂, NO₂, CO, HF, HCL and VOCs, arising from the metal works in Area 85, landfill gas flares in TKO Stage I and Stage II / III landfills, and burning of fossil fuels in the TKO Industrial Estates. However, the concentrations of these pollutants predicted in the Environmental Assessment Study of the MTR Tseung Kwan O Line Tseung Kwan O Area 86 Comprehensive Development Area (submitted under Section 16/4A Town Planning Ordinance in January 1999, and hereinafter called the “EA Study”) were well below the acceptable levels.

Study Area of Pak Shing Kok

3.3.6 Area 78 (Pak Shing Kok [PSK]) is a rural area, having only a few scattered houses. The major pollutant emission is from traffic on Wan Po Road.

3.4 Air Sensitive Receivers

3.4.1 In accordance with Annex 12 of the EIAO-TM, representative existing and planned air sensitive receivers (ASRs) in the proximity of the WCR, CBL, TKO and PSK developments and associated new roads were selected for air quality impact assessment. The ASRs are listed in Tables 3.4 – 3.6 and their locations are illustrated in Figures 3.1a and 3.1b.

3.4.2 The air quality impact at ground floor of the representative ASRs, which is the average height of the human breathing zone, were assessed in the study. Various height levels from low floors to top floors were also selected for assessment to show the vertical variation of the pollutant concentrations during operation phase of the Project.

Table 3.4 Representative Air Sensitive Receivers in the vicinity of Work Sites during Construction Phase

ID No.	Location	Use	Distance between ASR and work boundary(m)
OP1	O Pui Village Houses near Pak Shing Kok	Residential	252
V1	Village Houses in vicinity of Eastern Portal of WCR	Residential	74
OSC2	Ocean Shore	Residential	32
H3	Private Residential Development at the north of WCR (Planned)	Residential	30
H11	Private Residential Development at the north of WCR (Planned)	Residential	12
T1	Tin Hau Temple, south of KMS Development	Temple	25
PW	Ping Tin Estate	Residential	96
CP	Chung Pak House, Hong Pak Court	Residential	42
EHC1	Residential Development near Eastern Harbour Crossing (Under Construction)	Residential	8

Table 3.5 Representative Air Sensitive Receivers in the vicinity of Kowloon Section of WCR during Operation Phase

ID No.	Location	Use	Distance between ASR and emission sources (m)
LC1	Laguna City	Residential	20
CKL1	Existing Residential Development along Cha Kwo Ling Road – Cha Kwo Ling Building	Residential	2
CKL2	Existing Residential Development along Cha Kwo Ling Road – Hoi Chu Building	Residential	2
HS1	School Village of Kaolin Mine Site	Educational Institute	80
HS4	School Village of Kaolin Mine Site	Educational Institute	26
H1	Private Residential Development at the north of WCR (Planned)	Residential	55
H3	Private Residential Development at the north of WCR (Planned)	Residential	46
H11	KMS Housing Development at the South of WCR (Planned)	Residential	22
H12	KMS Housing Development at the South of WCR (Planned)	Residential	46
H15	KMS Housing Development at the South of WCR (Planned)	Residential	44
H17	KMS Housing Development at the South of WCR (Planned)	Residential	44
H20	KMS Housing Development at the South of WCR (Planned)	Residential	22
T1	Tin Hau Temple, south of KMS Development	Temple	30
S1	CCC Kei Fat Primary School (Under Construction)	Educational Institute	13
SG1	Block 9, Sceneway Garden	Residential	28
KH	SKH Kei Hau Secondary School	Educational Institute	20
PW	Ping Tin Estate	Residential	80
CP	Chung Pak House, Hong Pak Court	Residential	120
EHC1	Residential Development near Eastern Harbour Crossing (Under Construction)	Residential	13
EHC2	Residential Development near Eastern Harbour Crossing (Under Construction)	Residential	13
EHC5	Residential Development near Eastern Harbour Crossing (Under Construction)	Residential	13
STA	St. Antonius Primary School and Kindergarten	Educational Institutes	33
AMB	Lam Tin Ambulance Depot	Clinic	24

Table 3.6 Representative Air Sensitive Receivers in the vicinity of TKO Town Centre South during Operation Phase

ID No.	Location	Use	Distance between ASR and emission sources (m)
73Bb	Area 73B – Planned residential Area (R1)	Residential	37
73Bd	Area 73B – Planned residential Area (R1)	Residential	7
OSC2	Area 72 – Ocean Shores	Residential	36
OSC5	Area 72 – Ocean Shores	Residential	127
OSC8	Area 72 – Ocean Shores	Residential	5
TKC2	Area 57 – Park Central	Residential	42
TKC6	Area 57 – Park Central	Residential	36
TKC12	Area 57 – Park Central	Residential	27
TKC13	Area 57 – Park Central	Residential	38
TKP2	Area 55 – Site 55A – Tseung Kwan O Plaza	Residential	38
TKP5	Area 55 – Site 55A – Tseung Kwan O Plaza	Residential	19
BaG1	Area 65 – Site 65A – Bauhinia Garden	Residential	39
BaG3	Area 65 – Site 65A – Bauhinia Garden	Residential	39
BaG11	Area 65 – Site 65A – Bauhinia Garden	Residential	12
V1	Village Houses at North of Eastern Portal of WCR	Residential	102
74S4	Area 74S – Planned School Area	Educational Institutes	23
74S5	Area 74S – Planned School Area	Educational Institutes	37
74S6	Area 74S – Planned School Area	Educational Institutes	56
73B1	Area 73B – Planned School Area	Educational Institutes	45
73B2	Area 73B – Planned School Area	Educational Institutes	8
73B3	Area 73B – Planned Residential Area (R1)	Residential	9
73B4	Area 73B – Planned Residential Area (R1)	Residential	10
73B5	Area 73B – Planned Residential Area (R1)	Residential	19
SAPS	At. Andrew’s Catholic Primary School	Educational Institutes	2
67S1	Area 67 – Planned School Area	Educational Institutes	29
67S2	Area 67 – Planned School Area	Educational Institutes	18
67S4	Area 67 – Planned School Area	Educational Institutes	24
67S6	Area 67 – Planned School Area	Educational Institutes	22
66A2	Area 66 – Site 66A – Planned Residential Area (R1) (with 3 storeys commercial development at lower levels)	Residential	12
66A3	Area 66 – Site 66A – Planned Residential Area (R1) (with 3 storeys commercial development at lower levels)	Residential	21
66B1	Area 66 – Site 66B – Planned Residential Area (R1) (with 3 storeys commercial development at lower levels)	Residential	9
66B3	Area 66 – Site 66B – Planned Residential Area (R1) (with 3 storeys commercial development at lower levels)	Residential	16
66B5	Area 66 – Site 66B – Planned Residential Area (R1) (with 3 storeys commercial development at lower levels)	Residential	9
55B1	Area 55 – Site 55B – Tseung Kwan O Plaza (Phase2)	Residential	43
65B1	Area 65 – Site 65B – Planned Residential Area (R2)	Residential	65
65B2	Area 65 – Site 65B – Planned Residential Area (R2)	Residential	15
65B3	Area 65 – Site 65B – Planned Residential Area (R2)	Residential	14
65C1	Area 65 – Site 65C – Planned School Area	Educational Institutes	11
65C2	Area 65 – Site 65C – Planned School Area	Educational Institutes	12
66C1	Area 66C – Planned Other Specified Uses Area including Residential Uses	OU	24
66C2	Area 66C – Planned Other Specified Uses Area including Residential Uses	OU	14
66C3	Area 66C – Planned Other Specified Uses Area including Residential Uses	OU	12
68A1	Area 68A – Planned Other Specified Uses Area including Residential Uses	OU	38
78B1	Area 78 – Planned Residential Area (R3) (Site 78C)	Residential	25
78B2	Area 78 – Planned Residential Area (R3) (Site 78A)	Residential	15
78E1	Area 78 – Planned Residential Area (R3) (Site 78E)	Residential	79
78E3	Area 78 – Planned Residential Area (R3) (Site 78E)	Residential	37
78E5	Area 78 – Planned Residential Area (R3) (Site 78E)	Residential	16
78E6	Area 78 – Planned Residential Area (R3) (Site 78E)	Residential	15
S1	Area 78 – Planned School	Educational Institute	48
S2	Area 78 – Planned School	Educational Institute	43
N4	Area 86 – MTRC Area 86 Development (Under Construction)	Residential	15
N10	Area 86 – MTRC Area 86 Development (Under Construction)	Residential	20
N14	Area 86 – MTRC Area 86 Development (Under Construction)	Residential	12
N16	Area 86 – MTRC Area 86 Development (Under Construction)	Residential	2
N19	Area 86 – MTRC Area 86 Development (Under Construction)	Residential	24
N22	Area 86 – MTRC Area 86 Development (Under Construction)	Residential	6
MTR	MTR Tseung Kwan O Extension - Tiu Keng Leng Station	OU	8

3.5 Identification of Pollutant Sources

Construction Phase

3.5.1 According to the construction programme of the Project, there are four construction packages including:

· Package 1: TCS, Tiu Keng Leng (TKL) and PSK & Tseung Kwan O Stage I Landfill (TKOL-1) Development:

- TCS comprise the newly reclaimed land south of Po Yap Road, Eastern Drainage Channel and the toe along TKOL-1;

- TKL comprise the newly reclaimed land on the east of Ocean Shores (South of Chui Ling Road);

- PSK comprise the three large terraces on the east of TKOL-1 and Wan Po Road;

· Package 2: Western Coast Road including reclamation & toll plaza & at-grade road at TKO, tunnel, Kowloon viaduct and road;

· Package 3: Cross Bay Link;

· Package 4: Road P2 & Road D4 Flyover.

3.5.2 The potential construction dust impact and cumulative impact at the ASRs are identified as follows:

Package 1: TCS, TKL, PSK & TKOL-1 Development

3.5.3 During construction phase, no ASRs would be located adjacent to the construction site, except Bauhinia Garden and Ocean Shores. However, there would be minor modification of the existing Roads L661 and L861. Generation of significant dust impact at the ASRs would not be expected.

3.5.4 The construction works of Package 1 would not be operated concurrently with those land activities of WCR (Package 2) at TKO side, CBL (Package 3) and Road P2 & Road D4 Flyover (Package 4). No cumulative dust impact would be expected.

3.5.5 With the implementation of mitigation measures stipulated in Air Pollution Control (Construction Dust) Regulation, adverse construction dust impacts from the construction of local roads would not be expected. No quantitative assessment is required for ASRs in vicinity of TCS, TKL and TKOL-1 development site due to Package 1 construction works

3.5.6 Regarding PSK construction package, the major construction activities would be site formation (levelling and filling) at Pak Shing Kok platform and site formation for Pak Shing Kok Freshwater Service Reservoir. Potential dust impacts would be expected at the O Pui Village in vicinity of the construction site.

Package 2: Western Cross Road

3.5.7 For TKO side, the major dusty works including reclamation works (three different phases), construction of Toll Plaza, and Main Tunnel and associated works which would be undertaken separately. The nearest ASRs identified in vicinity of the works area include Ocean Shore and the village house located close to the Eastern Portal of the WCR. As the worst-case scenario, these two ASRs would be affected by reclamation works according to the construction programme. The work programme for three different Reclamation Work packages would not be overlapped and no cumulative dust impact would be expected. Quantitative assessment was carried out for these worst affected ASRs under worst-case scenario. According to the construction programme, no cumulative dust impacts would be expected arsing from construction works under Package 1, 3 & 4 within 500m from the work area of Package 2 work site.

3.5.8 For Kowloon side, the major works would be demolition and reprovision of ambulance depot, construction of western portal of WCR, road construction of WCR and associated slip roads. Potential dust impacts would be expected on the nearest ASRs located in vicinity of the works site including ASRs at Kaolin Mine Site Development close to the WCR, residential development near EHC, Ping Tin Estate and Chung Pak House, Hong Pak Court.

Package 3: Cross Bay Link

3.5.9 There are no ASRs located in the vicinity of the construction work areas (within 500m from the work area) for viaduct and bridge section of the CBL. Each construction task for WCR/CBL/Road P2 Interchange would be operated individually and no ASRs are located adjacent to the construction work area. Regarding the road section along Area 86, no concurrent construction activities would be operated simultaneously. It is anticipated that no adverse dust impacts would be expected on the proposed development on Area 86 with the adoption of dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation for individual construction activity.

3.5.10 Regarding the cumulative impact with other construction package, only construction of the road section along Area 86 and the Toll Plaza and at-grade roads of WCR would be constructed at the same period. However, the distance between these two areas exceeding 500m and therefore cumulative dust impact would not be expected.

Package 4: Road P2 & Road D4 Flyover

3.5.11 The roadworks for Road P2 including Bridge Section, Depressed Section and At-grade Section would not carried out at the same time according to the construction programme, cumulative dust impacts would not expected at the ASRs such as Ocean Shore. Minor dust impact arising from individual construction tasks for Road P2 and Road D4 Flyover on the ASRs in vicinity of the site would be expected with the implementation of dust mitigation measures stipulated in Air Pollution Control (Construction Dust) Regulation.

3.5.12 As stated in Section 3.5.3 – 3.5.11, potential construction dust impact would be expected at some ASRs. The following cases are considered to be the worst-case scenarios in the Project and quantitative assessment for construction dust impact at these ASRs was carried out.

Case 1 - O Pui Village houses (ASR OP1) due to site formation at Pak Shing Kwok;

Case 2 - Villages houses (V1) in vicinity of Eastern Portal of the WCR due to Reclamation Work Phase 2;

Case 3 - Ocean Shores (ASR OSC2) due to Reclamation Work Phase 3; and

Case 4 - ASRs (ASR H3, H11 and T1) at Kaolin Mine Development and ASRs (ASR PW, CP and EHC1) in vicinity of Western Portal of the WCR at Kowloon side due to construction of WCR and Western Portal of WCR.

Operation Phase

3.5.13 Vehicle exhaust emissions, in particular NO₂ and RSP, from new and existing roads would be the major pollutant sources during the operation phase. New traffic emission sources considered in the assessment include the proposed WCR, Road P2, Road D4 Flyover, CBL and associated new roads, and ventilation buildings for the WCR. Emissions from existing roads, and portal emissions from the existing EHC and emissions from the exhaust openings of the EHC ventilation building, which are located within the study area, would contribute to cumulative air quality impact.

3.5.14 The proposed WCR Tunnel is about 2,150m long. Indeed, approximately 172m and 200m full enclosures are proposed on WCR. Owing to the longitudinal transport of pollutants promoted by the statistical fluctuation of the traffic density, the meteorological condition, and the turbulence generated by the passing vehicles, air pollutants arising from vehicle emissions would be confined inside enclosure structures. The in-tunnel air quality is hence of concern, and was assessed based on their respective traffic flow features.

3.5.15 In addition to the vehicle exhaust emission from the road networks, industrial emissions from the existing Kwun Tong and Yau Tong industrial buildings and landfill gas emission from Sai Tso Wan Landfill have been considered in the cumulative air quality impact arising in the Kowloon area of the WCR. The landfill gas flaring emissions from TKO Stage I and Stage II/III Landfills has been considered in the cumulative air quality impact arising in the TKO area. The nitrogen dioxide and sulphur dioxide from chimney emissions from the TKO Industrial Estate was excluded in the assessment, as the chimneys are not located within 500m from the Project study area.

3.5.16 Major air pollutant emission sources in the study areas include:

(A) Kowloon Area (Kowloon section of WCR)

· Vehicular emissions from road networks.

· Portal emissions from the proposed WCR, the existing EHC, deck-over of Sceneway Garden and the Lei Yue Mun Road underpass (planned).

· Emissions from idling traffic at the toll plaza section of EHC.

· Emissions from the EHC exhaust ventilation building.

· Vehicular emissions inside tunnel of WCR and the proposed full enclosure.

· Flaring plant located at the Sai Tso Wan Landfill.

· Industrial emissions from factories in Kwun Tong and Yau Tong.

(B) TKO Area (including TKO section of WCR, TKO TCS, CBL & PSK)

· Vehicular emissions from road networks.

· Portal emissions from the WCR Tunnel, underpass section of link roads at WCR/CBL/Road P2 interchange and depressed Road P2.

· Emissions from idling traffic at the toll plaza of eastern portal of WCR.

· Emissions from the Mid-Ventilation Building.

· Flaring emissions from TKO Stage I and Stage II/III Landfills.

3.5.17 With the installation of high efficiency deodourization units, minimal odour impact would be expected from the proposed sewage pumping station at the TKOL-1 (located at the end of Road 861 near Area 86). The existing Tseung Kwan O Preliminary Treatment Works (TKOPTW) would be upgraded and deodorisation equipment would be installed to reduce the concentration of hydrogen sulphide. The separate distance between the existing TKOPTW and the planned sewage pumping station would be at least 760m, no adverse cumulative odour impact would be expected and quantitative odour assessment is therefore considered unnecessary.

3.6 Assessment Methodology

Construction Phase

Emission Inventory

3.6.1 Predicted dust emissions were based on emission factors from USEPA Compilation of Air Pollution Emission Factors (AP-42), 5th Edition. The major construction activities for the Project, which would be potential sources of construction dust in the Study Area, include:

Case 1 Pak Shing Kok Site Formation (levelling and filing)

- sand filling activities

- truck movement on unpaved haul road within the construction site

- wind erosion of open site

Pak Shing Kok Fresh Water Service Reservoir

- soil excavation activities

- transportation / handling of spoil

- wind erosion of open site.

Case 2 Reclamation Works at TKO (Phase II)

- backfilling

- transportation / handling of spoil

- truck movement on unpaved haul road within the construction site

- wind erosion of open site

Case 3 Reclamation Works at TKO (Phase III)

- backfilling

- transportation / handling of spoil

- truck movement on unpaved haul road within the construction site

- wind erosion of open site

Case 4 Construction works of WCR & Western Portal of WCR

- cut & cover tunnel (near Kaolin Site) & aggregate handling

- soil excavation

- transportation / handling of spoil

- truck movement on unpaved haul road within the construction site

- wind erosion of open site

3.6.2 The excavation rate, material handling rate, moisture content, silt content, no. of trucks and truck speed are provided by the Engineer. Detailed calculations of the emission factors are given in Appendix 3.1.

Table 3.7 Emission Factors for Dusty Construction Activities

Scenario	Activity		Emission Rate	Remarks
Case 1	Pak Shing Kok Site Formation (levelling and filling)	Material Handling	E = 0.1083 g/Mg =1.706 x 10^-3 g/s	· Volume of material: 567 m^3/day · Moisture content: 10 % · Average wind speed: 1.98 m/s · Density of spoil: 2 Mg/m^3 · 50% reduction by water suppression. · AP42, Section 13.2.4
		Unpaved Haul Road	E=344.7 g/VKT =2.394 x 10^-3 g/m/s	· Silt content: 10% · Moisture content: 10% · Vehicle speed: 10 kph · No. of vehicle: 50 trips/hr · 50% reduction by water suppression. · AP42, Section 13.2.2
		Wind Erosion	E = 0.85 Mg/hectare/year = 1.348 x 10^-6 g/m^2/s	· 50% reduction by water suppression. · AP42, Section 11.9.4
	Pak Shing Kok Fresh Water Service Reservoir	Material Handling	E = 0.1083 g/Mg =8.424 x 10^-5 g/s	· Volume of material: 28 m^3/day · Moisture content: 10 % · Average wind speed: 1.98 m/s · 50% reduction by water suppression. · AP42, Section 13.2.4
		Wet drilling	E = 8.4 x 10^-5 kg/Mg =6.533 x 10^-5 g/s	· Volume of material: 28 m^3/day · 50% reduction by water suppression. · AP42, Section 11.19.2
		Wind Erosion	E = 0.85 Mg/hectare/year = 1.348 x 10^-6 g/m^2/s	· 50% reduction by water suppression. · AP42, Section 11.9.4
Case 2 Reclamation Works at TKO	Phase II	Material Handling	E = 0.1083 g/Mg = 1.805 x 10^-2 g/s	· Volume of material: 6000 m^3/day · Moisture content: 10 % · Average wind speed: 1.98 m/s · Density of spoil: 2 Mg/m^3 · 50% reduction by water suppression. · AP42, Section 13.2.4
	Phase II	Unpaved Haul Road	E=344.7 g/VKT =2.394 x 10^-3 g/m/s	· Silt content: 10% · Moisture content: 10% · Vehicle speed: 10 kph · No. of vehicle: 50 trips/hr · 50% reduction by water suppression. · AP42, Section 13.2.2
	Phase II	Wind Erosion	E = 0.85 Mg/hectare/year = 1.348 x 10^-6 g/m^2/s	· 50% reduction by water suppression. · AP42, Section 11.9.4
Case 3 Reclamation Works at TKO	Phase III	Material Handling	E = 0.1083 g/Mg = 9.025 x 10^-3 g/s	· Volume of material: 3000 m^3/day · Moisture content: 10 % · Average wind speed: 1.98 m/s · Density of spoil: 2 Mg/m^3 · 50% reduction by water suppression. · AP42, Section 13.2.4
	Phase III	Unpaved Haul Road	E=344.7 g/VKT =2.394 x 10^-3 g/m/s	· Silt content: 10% · Moisture content: 10% · Vehicle speed: 10 kph · No. of vehicle: 50 trips/hr · 50% reduction by water suppression. · AP42, Section 13.2.2
		Wind Erosion	E = 0.85 Mg/hectare/year = 1.348 x 10^-6 g/m^2/s	· 50% reduction by water suppression. · AP42, Section 11.9.4
Case 4 Construction works of WCR and Western Portal of WCR	Cut & Cover Tunnel (near Cha Kwo Ling Kaolin Mine Site)	Material Handling	E = 0.1083 g/Mg = 8.273 x 10^-4 g/s	· Volume of material: 275 m^3/day · Moisture content: 10 % · Average wind speed: 1.98 m/s · Density of spoil: 2 Mg/m^3 · 50% reduction by water suppression. · AP42, Section 13.2.4
	Cut & Cover Tunnel (near Cha Kwo Ling Kaolin Mine Site)	Wet Drilling	E = 8.4 x 10^-5 kg/Mg = 6.417 x 10^-4 g/s	· Volume of material: 275 m^3/day · Density of spoil: 2 Mg/m^3 · 50% reduction by water suppression. · AP42, Section 11.19.2
	Cut & Cover Tunnel (near Cha Kwo Ling Kaolin Mine Site)	Wind Erosion	E = 0.85 Mg/hectare/year = 1.348 x 10^-6 g/m^2/s	· 50% reduction by water suppression. · AP42, Section 11.9.4
	Construction of WCR	Material Handling	E = 0.1083 g/Mg =8.123 x 10^-4 g/s	· Volume of material: 270 m^3/day · Moisture content: 10 % · Average wind speed: 1.98 m/s · Density of spoil: 2 Mg/m^3 · 50% reduction by water suppression. · AP42, Section 13.2.4
	Construction of WCR	Wet drilling	E = 8.4 x 10^-5 kg/Mg = 6.3 x 10^-4 g/s	· Volume of material: 270 m^3/day · Density of spoil: 2 Mg/m^3 · 50% reduction by water suppression. · AP42, Section 11.19.2
	Construction of WCR	Unpaved Haul Road	E=344.7 g/VKT =1.436 x 10^-3 g/m/s	· Silt content: 10% · Moisture content: 10% · Vehicle speed: 10 kph · No. of vehicle: 30 trips/hr · 50% reduction by water suppression. · AP42, Section 13.2.2
	Construction of WCR	Wind Erosion	E = 0.85 Mg/hectare/year = 1.348 x 10^-6 g/m^2/s	· 50% reduction by water suppression. · AP42, Section 11.9.4

3.6.3 The Air Pollution Control (Construction Dust) Regulation specified that dust depression measures such as watering should be applied for the construction site. Dust emission from the site would be reduced by 50% if watering with complete coverage of active construction area twice a day. This assumption was considered in the construction dust impact assessment.

3.6.4 12-hour (07:00-19:00) was assumed for the reclamation works in the assessment (i.e.. Cases 2 & 3). Besides, 10-hour working day (08:00-18:00) was assumed for all other construction works (ie. Cases 1 & 4) in the assessment. Wind erosion of open sites would take place over the whole day.

Dispersion Modelling & Concentration Calculation

3.6.5 Fugitive Dust Model (FDM) (1993 version) was adopted to assess potential dust impact from the construction works. One year sequential meteorological data for the year 2003 from the Hong Kong Observatory Junk Bay Station 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.

3.6.6 Daily TSP concentrations were calculated as follows:

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

3.6.7 The background TSP (77 mg/m³) for rural/new development, based on the latest five years (1999 – 2003) average monitoring data (from EPD monitoring stations including Eastern, Central/Western, Sham Shui Po, Kwun Tong, Kwan Chung and Tsuen Wan) for urban development areas as defined in the Guidelines on Assessing the Total Air Quality Impacts, was adopted as an indication of the future TSP background concentration.

Operation Phase

Emission Inventory

Vehicle Emissions from Open Roads

3.6.8 The vehicular emission factors (Fleet Average Emission Factors – EURO4 Model) for the year 2011 were adopted for the assessment. The composite emission factors for the road links were calculated as the weighted average of the emission factors of different types of vehicles. As emission factors beyond 2011 are not available, the 2011 vehicle emission factors have been used for traffic beyond 2011 as a worst-case scenario.

3.6.9 A sensitivity test was conducted to determine the worst air quality scenario, in terms of the traffic flow and emission factors, for major proposed new roads at both Kowloon area and TKO area for the years 2016 and 2031 (refer to Appendix 3.2). Results indicate that the worst scenario in terms of air pollution from vehicle emissions for both areas would occur in AM Peak of year 2031. Details for the calculations of the composite emission factors for each road link are given in Appendix 3.3.

3.6.10 All major roads including WCR, CBL, Road P2 and Road D4 flyover within 500m of the project development were incorporated into the assessment.

3.6.11 The assessment should be based on projected peak hour flows for the worst year within 15 years of commencement of operation. According to the traffic forecast, 2031 is the worst year within 15 years of commencement of the operation.

3.6.12 Emissions from idling vehicles nears the EHC toll plaza and the WCR toll plaza were included in the model based on the assumption that the vehicles are queuing on all lanes approaching or leaving the tunnel portal for a distance of 100m. The maximum steady queues at the EHC toll plaza and WCR toll plaza are summarised in Table 3.8 and 3.9.

Table 3.8 Queuing Forecast at EHC Toll Plaza

EHC Toll Plaza	Maximum Steady Queue (No. of vehicles)
Eastbound	80
Westbound	80

Table 3.9 Queuing Forecast at WCR Toll Plaza

WCR Toll Plaza	Maximum Steady Queue (No. of vehicles)
Eastbound	80
Westbound	93

3.6.13 The emission factors for idling vehicles in the assessment were obtained from the Final Report of Feasibility Study for Developments at Cha Kwo Ling Kaolin Mine Site. Calculation of emission factors for queuing lanes is provided in Appendix 3.4.

Table 3.10 Vehicle Idling Emission Factors

Vehicle Type	Idling Emission Factor (g/min/veh)
	NOx	RSP
Public Light Bus, Light Goods Vehicles	0.5	0.043
Bus, Medium Goods Vehicles and Heavy Goods Vehicles	2.0	0.043
Taxi	0.5	0.043
Private Car	0.2	Negligible

Emissions from Mid-Ventilation Building of WCR Tunnel

3.6.14 The proposed ventilation system of WCR has taken account of the preliminary assessment result that not more than 10% vehicle emission from the westbound tunnel should be allowed to emit from the Kowloon side portal, 90% of the westbound WCR tunnel emissions would be extracted and discharged at the Mid-Ventilation Building, which located at the junction of Chui Ling Road and Choi Ming Street in Tiu Keng Leng area (see Appendix A3.5). The residual 10% of the westbound WCR tunnel emission would be exhausted at the Kowloon portal. The exhaust vent shaft would face in an upward direction with 3m/s of exit velocity and the release height would be at 10m above ground level.

Portal Emissions from Vehicular Tunnel

3.6.15 The proportion of traffic emissions expelled from the portals and the vent shaft(s) of a vehicular tunnel depends on the ventilation design of the tunnel. For this assessment, the portal emissions from the WCR tunnel (10% of the westbound WCR tunnel emission would be discharged through the WCR portal at Kowloon area and 100% of the eastbound WCR tunnel emission would be discharged through the WCR portal at the TKO area), Lei Yue Mun underpass, Sceneway Garden deck-over and recommended noise enclosures on WCR were calculated based on the predicted 2031 peak hour traffic flow and the traffic composition from the traffic forecast. Detail calculation and the locations of all portals, underpass and full enclosures are shown in Appendix 3.5.

Portal Emission & Vent Shaft Emissions from EHC

3.6.16 According to the EHC EIA Final Report, only 30% of the tunnel emissions would be emitted from the portal exit, with the remainder extracted at the ventilation exhaust building. Portal emissions from EHC were calculated based on the above assumption, the predicted 2031 peak hour traffic flow and the traffic composition from the traffic forecast. Detail calculation of the portal emission is shown in Appendix 3.5. The location of the EHC ventilation exhaust building is shown in Figure 3.3.

Industrial Emission and Landfill Gas Flaring Plant Emission

3.6.17 Emissions from the industrial buildings at Kwun Tong and Yau Tong would contribute to the cumulative impact of NO₂. Air quality impacts due to industrial emissions within 1km radius of the subject site have been considered in the assessment. The inventory of industrial chimneys maintained by EPD (received in September 2004) was used to assess the impacts from the chimney emissions. A total number of 12 active diesel oil-fired furnaces were identified within 1km radius of the subject site from EPD’s register. The locations of the chimney were shown in Figure 3.2. Regarding TKO side, there was no industrial chimney emissions identified within the 500m of the Project study area.

3.6.18 The emission factor for NO₂ was based on AP42 (USEPA 1998: Table 1-3-1 Criteria Pollutant Emission Factors for Fuel Oil Combustion). The calculation of chimney emission factor is shown in Appendix 3.6.

3.6.19 Flaring emission from the landfill gas flaring plant and the Thermal Oxidizer at the TKO Stage I and Stage II/III Landfills also included in the assessment. The emission factor and those physical information were based on the monitoring data given by EPD. The locations of the flare stack and thermal oxidixers were shown in Figure 3.3. According to the information provided by EPD, the SO₂ emission is less than 1 mg/m3. Due to insignificant SO₂ emission from landfill sites, only NO₂ emissions were assessed in the study. The calculation of landfill gas emission is shown in Appendix 3.7.

3.6.20 Emissions from the landfill gas flaring plant at Sai Tso Wan Landfill was also taken into account in the assessment, by adopting the emission factor used in the Final Report of Feasibility Study for Developments at Cha Kwo Ling Kaolin Mine Site.The pollutant emission limits and operational parameters of Sai Tso Wan Landfill Flare are summarised in Table 3.11. The location of the landfill gas flaring plant is shown in Figure 3.3. The calculation of Sai Tso Wan landfill gas emission is shown in Appendix 3.7.

Table 3.11 Pollutant Emission Limits and Operational Parameters of Sai Tso Wan Landfill Flare

Parameters
Emission Limit of NOx (mg/m^3)	400
Emission Limit of RSP (mg/m^3)	50
Exhaust Volume Flow Rate (m^3/hr)	19,110
Flare Stack Height (m)	6
Flare Stack Diameter (m)	1
Exit Temperature (°C)	900

Remark: Reference from Final Report of Feasibility Study for Developments at Cha Kwo Ling Kaolin Mine Site.

Vehicular Emission inside WCR Tunnel and Proposed Full Enclosure and Road P2 Deckover

3.6.21 In accordance with the “Practice Note on Control of Air Pollution in Vehicle Tunnels”, the air quality inside the tunnel should achieve the EPD recommended standard of 1ppm NO₂ concentration. Additional ventilation system should be provided when exceeding the above limit.

3.6.22 The air quality inside the 2,150m WCR Tunnel with uni-directional traffic flow. As provided by the ventilation engineer, the air change rate per hour for the WCR Tunnel Eastbound and Westbound, would be 6.07 and 6.14 respectively based on the supply airflow rates. A conversion factor of 12.5% including tailpipe NO₂ emission (taken as 7.5% of NO_x) plus 5% of NO₂/NOx for tunnel air recommended in PIARC for air expelled from the tunnel was taken in this assessment as the inside tunnel conversion factor. It was assumed normal traffic flow condition with the vehicle speed of 50 kph in the assessment. Detail calculations of in-tunnel air quality for WCR Westbound and Eastbound are presented in Appendices 3.8 and 3.11 respectively.

3.6.23 Two sections of full enclosures (172m long and 200m long covering the eastbound and westbound carriages) on WCR and the longest deckover (80m long) on Road P2 were calculated based on the empirical formulas of fluid dynamics. A conversion factor of 12.5% including tailpipe NO₂ emission (taken as 7.5% of NO_x) plus 5% of NO₂/NOx for tunnel air recommended in PIARC for air expelled from the tunnel was taken in this assessment as the inside tunnel conversion factor. Two scenarios were considered for the full enclosures/deckover, i.e. normal traffic flow condition and congested traffic flow condition. It was assumed that under normal traffic flow condition, the vehicles are at a speed of 50 kph, whereas under congested mode, the separation between vehicles is assumed to be 1 m. The calculation of in-tunnel air quality for two sections of full enclosures is shown in Appendix 3.9. The calculation of in-tunnel air quality of the longest deckover at Road P2 is presented in Appendix 3.10. The Northbound and Southbound of Road P2 under the deckover would be separated by a concrete structure, the Northbound of Road P2 which would have a higher traffic emission, was calculated in this assessment for demonstration of the compliance with the in-tunnel air quality standard.

3.6.24 The ratio of guideline standard of CO (5-minutes) concentration to NO₂ (5-minutes) concentration in mg/m3 is 64 to 1, however, the emission rate of CO is less than 64 times NO2 emission rate. Therefore, CO would comply with the standard if the predicted NO₂ concentration was below 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, it is expected that SO₂ would also comply with the tunnel air quality limit.

Dispersion Modelling

Vehicle Emissions from Open Roads

3.6.25 The CALINE4 dispersion model was used for calculation of the hourly NO₂, 24-hour NO₂ and 24-hour RSP concentrations. For the calculation of the NO₂ concentrations, the vehicular emission factor for NO_x was used and the conversion factor from NO_x to NO₂ was assumed to be 20%.

3.6.26 The USEPA publication: Screening Procedures for Estimating the Air Quality Impact of Stationary Source (EPA-454/R-92-019), recommends a conversion factor of 0.4 to convert hourly average concentrations into daily average concentrations. This conversion factor was used in the assessment.

3.6.27 Peak hour traffic would occur in daytime (morning), and the following worst-case daytime meteorological conditions were assumed in the CALINE4 model.

· Wind speed: 1 m/s

· Wind direction: 360 wind direction

· Wind variability: 18^o

· Stability class: D

· Surface roughness: 1m

· Mixing height: 500 m

3.6.28 Secondary air quality impacts arising from the implementation of roadside noise barriers and enclosures were also incorporated into the air quality model. It was assumed that all traffic pollutants generated from road sections with vertical noise barriers would be emitted from the top of the noise barriers. For cantilevered noise barriers and semi-enclosures, it was assumed that dispersion of the traffic pollutants would have effect similar to assuming that traffic pollutants would be emitted from the top of the canopies and semi-enclosures at a point close to the central divider of the road. The detailed dimensions and locations of the noise barriers were described in Section 4.6 and 4.9.9 to 4.9.20 and Figures 4.6 to 4.7.

3.6.29 Portal emissions from the WCR Tunnel, the existing EHC, the deck-over of Sceneway Garden, the deck-over and proposed full enclosure along the WCR, tunnel sections of link roads of WCR/CBL Road P2 interchange and the decked road sections of Road P2, were calculated based on the procedures in Section III of the Permanent International Association of Road Congress Report (PIARC), 1991. It was assumed that emissions would emerge as an air jet along the axis of the road so that only the well-diluted parts gradually shear off. The pollutants were assumed to be ejected as a volume source in the model, with 2/3 of the total emissions dispersed in the first 50m, and 1/3 of the total emissions dispersed in the second 50m. The portal emissions were modelled as volume sources in ISCST3 model.

Vent Shaft Emissions from Vehicular Tunnels, Industrial Emissions and Landfill Gas Flaring Plant Emission

3.6.30 Emissions from the vent shafts of the vehicular tunnels, chimney emissions and landfill gas flaring plant emissions were modelled as point sources employing the Industrial Source Complex Short-Term (ISCST3) dispersion model. AM peak hour traffic flow was adopted in the assessment, the meteorological conditions assumed in the ISC3 model as same as the CALINE4 model.

Concentration Calculation

3.6.31 To obtain the cumulative pollutant concentration at each receptor, two sets of 360 values each were first derived from the CALINE4 and the ISCST3 models respectively, for the 360 wind directions. The corresponding components of these two sets of 360 values were then added together and the highest value among the 360 wind directions was identified and considered as the highest predicted pollutant concentration level at the receptor.

3.6.32 Background pollutant concentrations were added to the results calculated above to produce the worst-case concentrations. As the data at Kwun Tong station obtained for the years 2000 and 1998 were below their respective minimum data requirement of 66% for number of data within the period and the data in Year 2002 were insufficient for calculation of annual average values, the air pollutant concentrations measured at Kwun Tong were not used to represent the background concentrations.

3.6.33 The background pollutant values adopted for assessment were based on the EPD “Guideline on Assessing the ‘TOTAL’ Air Quality Impacts”. In the categorisation of monitored air quality data, Kwun Tong is categorised as urban or industrial development. Hence, the latest five years (1999 – 2003) average monitoring data for similar type of development area including Eastern, Central/Western, Sham Shui Po, Kwun Tong, Kwan Chung and Tsuen Wan were adopted to represent the background air quality in this project. Although Junk Bay is defined as rural/ new development in the categorisation, the air pollutant value for the same assumption as Kowloon Area is considered to represent the worst-case scenario. The background air pollutant concentrations used in the assessment are presented in Table 3.12.

Table 3.12 Background Air Pollutant Concentration for Urban Development

Parameters	Concentration (mg/m^3)
Sulphur Dioxide	19
Nitrogen Dioxide	64
Ozone	27
TSP	77
RSP	51

3.7 Identification, Prediction and Evaluation of Air Quality Impacts

Construction Phase

3.7.1 The predicted TSP concentration at the representative ASRs under the worst case scenarios identified in Section 3.6 is presented in Table 3.13.

Table 3.13 Predicted TSP Concentrations at Representative Air Sensitive Receivers

Scenarios	ASRs ID	TSP Concentration (mg/m^3)
		1 – hour Average	24 – hour Average
Case 1	OP1	499	277
Case 2	V1	519	319
Case 3	OSC2	995	551
Case 4	H3	366	217
	H11	366	219
	T1	285	195
	PW	206	145
	CP	278	195
	EHC1	456	269

Remark: Background TSP concentration of 77 mg/m³ is included.

3.7.2 Assessment results indicated that some representative ASRs (OP1, V1, OSC2 and EHC1) would not comply with the criteria. It is expected that dust suppression measures at all cases would be required in order to achieve compliance with the AQO limit. No adverse construction dust impact on the other ASRs in vicinity of the construction sites with the implementation of dust suppression measures as stipulated in Air Pollution Control (Construction Dust) Regulation.

Operation Phase

Kowloon Area

3.7.3 The predicted average NO₂ and RSP concentrations at the representative ASRs are summarized in Appendix 3.12. The predicted concentrations are the cumulative result of emissions from:

· Open road sections.

· WCR tunnel portals.

· Recommended noise enclosures on WCR.

· Existing roads including EHC, Lei Yue Mun Road underpass (planned) and the deck-over of Sceneway Garden; idling emissions from EHC toll plaza; emissions from EHC vent shafts.

· Chimney emissions in the Yau Tong industrial area.

· Landfill gas flaring plant emissions.

3.7.4 As indicated in Appendix 3.12, the average NO₂ and RSP concentrations at all the representative ASRs would comply with the AQO limits. The concentrations of 1-hour average NO₂, 24-hour average NO₂ and 24 hour average RSP were predicted to range from 70 to 223 mg/m³, 67 to 128 mg/m³, 52 to 72 mg/m³, respectively. The highest average concentrations of 1-hour NO_2, 24-hour average NO_2, and 24-hour average RSP are predicted at ASR EHC5. The predicted hourly average NO₂, 24-hour average NO₂ and RSP concentration contours at 1.5m above local ground are shown in Figures 3.12 to 3.14.

WCR Tunnel and Proposed Full Enclosure and Road P2 Deckover

3.7.5 For the air quality assessment inside the WCR tunnel eastbound and westbound, the predicted NO₂ concentrations are 1418 mg/m³ and 1410 mg/m³ respectively, and comply with the Tunnel Air Quality Objective (1800 mg/m³). Besides, the predicted maximum NO₂ concentrations inside the two sections of the two full enclosures at WCR (Kowloon side) during normal traffic condition would be 469 mg/m³ & 455 mg/m³ respectively; while predicted maximum NO₂ concentrations under congested traffic flow condition would be 694 mg/m³ and 742 mg/m³, respectively. The predicted maximum NO₂ concentrations at the proposed longer deckover on Road P2 during normal traffic condition and congested traffic condition would be 161 mg/m³ and 182 mg/m³, respectively. It is expected the air quality in another deckover on Road P2 with shorter length would also comply with the criteria.

TKO Area

3.7.6 The predicted maximum and averaged NO₂ and RSP concentrations at the representative ASRs are summarized in Appendix 3.12. The predicted concentrations are the cumulative result of emissions from:

· Open road sections

· WCR tunnel portals

· Mid-Ventilation Building of WCR Tunnel

· Decked sections of Road P2

· Tunnel sections of link roads of WCR/ CBL Road P2 interchange

· Idling vehicles queuing at the WCR toll plaza

· Flaring emissions from TKO Stage I and Stage II/III Landfills

3.7.7 As indicated in Appendix 3.12, the average NO₂ and RSP concentrations at some representative ASRs would not comply with the AQO limits. The concentrations of 1-hour average NO₂, 24-hour average NO2 and 24 hour average RSP were predicted to range from 66 to 314 mg/m³, 65 to 164 mg/m³, 51 to 96 mg/m³, respectively. The highest predicted average concentrations of 1-hour average NO_2, 24-hour average NO_2, and 24-hour average RSP are 314 mg/m³, 164mg/m³, and 96mg/m³ at ASR 73B5 respectively. The exceedances of 1-hour average NO₂ and 24-hour average NO₂ predicted at ASR 73B5 due to emission from Mid-ventilation Building of WCR. The predicted 24-hour average NO₂ at ASR V1, which would be dominantly affected by portal emission from eastern portal of the WCR, would just marginally comply with the criterion. Mitigation measures would be provided in order to achieve compliance with the AQO limit.

3.8 Mitigation Measures

Construction Phase

3.8.1 To ensure compliance with the guideline level and AQO at the ASRs, the Air Pollution Control (Construction Dust) Regulation should be implemented and good site practices should be incorporated into the contract clauses to minimize construction dust impact. A number of practical measures are listed below:

· Use of regular watering, with complete coverage, to reduce dust emissions from exposed site surfaces and unpaved roads, particularly during dry weather.

· Use of frequent watering for particularly dusty construction areas and areas close to ASRs.

· Side enclosure and covering of any aggregate or dusty material storage piles to reduce emissions. Where this is not practicable owing to frequent usage, watering shall be applied to aggregate fines.

· Open stockpiles shall be avoided or covered. Where possible, prevent placing dusty material storage piles near ASRs.

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

· Establishment and use of vehicle wheel and body washing facilities at the exit points of the site.

· Provision of wind shield and dust extraction units or similar dust mitigation measures at the loading points, and use of water sprinklers at the loading area where dust generation is likely during the loading process of loose material, particularly in dry seasons/ periods.

· Imposition of speed controls for vehicles on unpaved site roads. Ten kilometers per hour is the recommended limit.

· Where possible, routing of vehicles and positioning of construction plant should be at the maximum possible distance from ASRs.

· Instigation of an environmental monitoring and auditing program to monitor the construction process in order to enforce controls and modify method of work if dusty conditions arise.

3.8.2 As shown in Table 3.13, after watering with complete coverage area twice a day as stated in S.3.6.3, the predicted 24-hour TSP concentrations at ASRs OP1 and EHC1 would still exceed the TSP criteria due to located near to PSK site formation and WCR construction works, respectively. The predicted 1-hour and 24-hour TSP concentrations at ASR V1 and OSC2 would still exceed the TSP criteria due to located adjacent to WCR reclamation works Phase 2 & 3. In order to minimize the air quality impact during the construction, the following additional mitigation measures for the haul roads within the PSK site formation, WCR construction works and WCR reclamation works phase 2 & 3 area proposed:

For PSK site formation (levelling & filling) and Construction of WCR

· Strictly limit the truck speed on site not more than 10 km per hour and watering the haul roads at least 4 times a day to reduce the dust generation by 75%, with reference to Control Techniques for Particulate Emissions from Stationary Sources, Volume 2, US Environmental Protection Agency 1982..

For WCR reclamation works phase 2 & 3

· Strictly limit the truck speed on site not more than 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.

3.8.3 With the implementation of the recommended mitigation measures, the emission factors for dusty construction activities are summarized in Table 3.14. Detailed calculations of the emission factors are provided in Appendix 3.1.

Table 3.14 Emission Factors for Dusty Construction Activities (With Mitigation Measures)

Scenario	Activity		Emission Rate
Case 1 Pak Shing Kok Site Formation (levelling and filling)	Site formation	Unpaved Haul Road Wind Erosion	E = 1.197 x 10^-3 g/m/s E=6.738 x 10^-7 g/m^2/s
Cases 2 & 3 Reclamation Works at TKO	Phases II & III	Unpaved Haul Road Wind Erosion	E = 4.787 x 10^-4 g/m/s E=2.695 x 10^-7 g/m^2/s
Case 4 Construction works of WCR and Western Portal of WCR	Construction of WCR	Unpaved Haul Road Wind Erosion	E = 7.181 x 10^-4 g/m/s E= 6.738x 10^-7 g/m^2/s

3.8.4 As indicated in Table 3.15, the predicted 1-hour and 24-hour TSP concentrations at all ASRs would comply with the AQO criteria with the implementation of the mitigation measures. The predicted hourly and daily average TSP concentration contours at 1.5m above local ground are shown in Figure 3.4 to 3.11. There is no air sensitive use within the areas with exceedance of either hourly or daily TSP criteria and outside the work boundaries. The sampling output files are given in Appendix 3.14.

Table 3.15 Predicted TSP Concentrations at Representative Air Sensitive Receivers (Mitigated)

Scenarios	ASRs ID	TSP Concentration (mg/m^3)
		1 – hour Average	24 – hour Average
Case 1	OP1	303	195
Case 2	V1	220	169
Case 3	OSC2	298	203
Case 4	EHC1	281	196

Remark: Background TSP concentration of 77 mg/m³ is included.

Operation Phase

Kowloon Area

3.8.5 According to the predicted results of all cumulative emissions at Kowloon side, all the representative ASRs comply with the AQO limit, thus no further mitigation measure is required.

TKO Area

3.8.6 As discussed in Section 3.7.8, the ASR would experience 1-hour and 24-hour average NO₂ concentrations in excess of or marginally comply with the AQO limits. In order to achieve compliance with the AQO limit, it is proposed that:

· Provision of a ventilation building at the eastern portal of WCR (Eastern Portal Ventilation Building) and it should be designed to extract 70% of the tunnel emission from the eastbound carriageway of the WCR tunnel. Then 30% of the tunnel emission from eastbound carriageway would be discharged through the WCR portal at the TKO area. The exhaust vent shaft of the ventilation building are proposed to be designed to exhaust in upward direction and the exhaust height should be at least 25m above ground level to prevent adverse air quality impact on the nearby ASRs (e.g. ASR V1).

· The Mid-ventilation building should be relocated from Tiu Keng Leng to the proposed reclamation area near CBL/WCR/Road P2 Interchange. The mid-ventilation building on the reclamation area should be at least 350 m to south of Ocean Shores. There would be two exhaust vent pipes discharge the in-tunnel air to the exhaust vent shaft. The exhaust vent shaft of the ventilation building would be upward direction with the exit velocity of 16 m/s, and release height would be 6 m above ground.

· The preliminary design of the ventilation buildings (including exit height, exhaust directions, exit velocity, design airflow rate and the exhaust diameter of the ventilation building) is summarized in Table 3.16.

Table 3.16 Design of Ventilation Building at the eastern portal of WCR and Mid-Ventilation building

		Design Airflow Rate (m^3/s)	Exit Velocity (m/s)	Exit Height (m)	Exhaust Diameter (m)	Exhaust Direction
Ventilation Building at eastern portal		321	16	25	5.1	Upward
Mid-Ventilation Building	Vent 1	228	16	6	4.3	Upward
	Vent 2	210	16	6	4.1	Upward

3.8.7 The locations of proposed Eastern Portal Ventilation Building and the Mid-Ventilation Building are shown in Figure A1. With the implementation of the proposed mitigation measures, it was predicted that no ASR would experience air pollutants in excess of the AQO limits. As shown in Appendix 3.13, the predicted 1-hour average concentrations of NO₂, 24-hour average concentrations of NO₂, and 24-hour average concentrations of RSP would range from 69 to 192 mg/m³; 66 to 115 mg/m³; and 52 to 64 mg/m³, respectively. The predicted hourly average NO₂, 24-hour average NO₂ and RSP concentration contours at 1.5m above local ground (mitigated scenario) are shown in Figures 3.15 to 3.17. All the air sensitive uses within the study area would comply with the AQOs. The sampling output files were given in Appendices 3.14 and 3.15.

3.9 Residual Environmental Impact

Construction Phase

3.9.1 With the implementation of the mitigation measures as stipulated in the Air Pollution Control (Construction Dust) Regulation, no adverse residual impact would be anticipated during the construction phase.

Operation Phase

3.9.2 With the implementation of the recommended ventilation systems for the WCR tunnel, the relocation of Mid-ventilation building and the addition of Eastern Portal Ventilation Building with directing the exhaust vent shaft away from the sensitive receivers, no adverse residual impact would be anticipated during the operational phase.

3.10 Environmental Monitoring and Audit Requirements

Construction Phase

3.10.1 Environmental monitoring and audit should be conducted during the construction phase of the Project so as to check compliance with legislative requirements. Details of the monitoring and audit programme are contained in a stand-alone EM&A Manual.

Operation Phase

3.10.2 Since no adverse operational air quality impacts would occur, environmental monitoring and audit is not deemed necessary during the operation phase.