8.             Construction Dust IMPACT

Introduction

8.1          Assessment on the potential dust impacts associated with the construction phase of the Project is presented in this section.  Representative Air Sensitive Receivers (ASRs) in the vicinity of the study area are identified.  The potential dust impacts on these ASRs arising from dust emission from construction activities associated with the Project have been assessed and appropriate mitigation measures are proposed to alleviate the potential air quality impacts.

8.2          The train to be employed for the Shatin to Central Link (SCL) will be electrically operated, air quality impact associated with train emission is therefore not anticipated during operation phase.  Exhausts for general ventilation and smoke extraction facilities will also be carefully positioned to avoid causing nuisance to the surrounding environment.  Thus, air quality impact during operation phase is considered insignificant and will not be assessed in this section.

Environmental Legislation, Standards and Guidelines

8.3          The criteria and guidelines for air quality assessment are laid down in Annex 4 and Annex 12 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM).  In addition, specific requirements on air quality assessment for this Project are stipulated in Clause 3.4.2 of the EIA Study Brief (No. ESB-193/2008).

Air Quality Objectives & EIAO-TM

8.4          The Air Pollution Control Ordinance (APCO) provides the statutory authority for controlling air pollutants from a variety of sources.  The Hong Kong Air Quality Objectives (AQOs), which stipulate the maximum allowable concentrations over specific periods for typical pollutants, should be met. The AQOs are listed in Table 8.1.

 

Table 8.1           Hong Kong Air Quality Objectives

Pollutant

Maximum Concentration (µg/m3) (1)

Averaging Time

1 hour(2)

8 hour(3)

24 hour(3)

3 month(4)

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

-

-

-

-

Lead

-

-

-

1.5

 

Notes:

(1)         Measured at 25°C and one atmosphere .

(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.

 

8.5          The EIAO-TM stipulates that the hourly TSP level should not exceed 500 mgm-3 (measured at 25oC and one atmosphere) for construction dust impact assessment. 

Air Pollution Control (Construction Dust) Regulation

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

Air Pollution Control Ordinance – Control of Emissions from Specified Processes

8.7          A licence is required for the operation of Cement Work (Concrete Batching Plant) under Part IV of APCO.  Application for licence should be made to EPD.  EPD may either grant or refuse to grant a licence subject to whether the applicant can fulfil the environmental standards to avoid causing air pollution.  If EPD decides to grant the licence, a set of conditions will be imposed to prevent adverse impact from the discharge of air pollutant emissions.

Description of the Environment

Environs

8.8          The Project alignment is an extension of the existing East Rail Line (EAL) from the Hung Hom Station (HUH) across the harbour to new Exhibition Station (EXH) and Admiralty Station (ADM).  The locality of the Project Area is a developed urban area with major land uses including commercial, residential and open spaces.

Background Air Quality

8.9          The study areas include both Kowloon side (i.e. Hung Hom) and Hong Kong Island side (i.e. Causeway Bay, Wan Chai and Admiralty) as well as an offsite works area (i.e. Shek O).  For Kowloon side, there is no EPD general air quality monitoring station located in the vicinity of the study area. Since Hung Hom area, in accordance with the Guidelines in Assessing the ‘TOTAL’ Air Quality Impacts, is categorized as urban area, the recent five years (2006 –2010) annual average monitoring data recorded at EPD’s general air quality monitoring stations in urban areas are therefore taken to estimate the background concentration.  With reference to EPD’s Air Quality Annual Report, the EPD’s general air quality monitoring stations in urban areas considered in this assessment include Central/Western, Kwun Tong, Sham Shui Po, Tsuen Wan and Kwai Chung.  The annual average air pollutant concentrations recorded at these monitoring stations are presented in Table 8.2.  The background concentration adopted for this assessment for Kowloon side is estimated as the mean of these annual average concentrations as shown in the table.

Table 8.2           Background Air Pollutant Concentrations adopted in this Assessment (Kowloon Side)

Urban Stations

Annual Average TSP Concentration (μg/m3)

TSP Background Concentration (μg/m3)

2006

2007

2008

2009

2010

Tsuen Wan

82

79

67

63

63

70.8

Kwai Chung

81

85

79

70

71

77.2

Sham Shui Po

79

79

81

77

76

78.4

Kwun Tong

75

82

72

70

67

73.2

Central/Western

78

77

78

73

76

76.4

 

 

 

 

 

Average

75.2

Note:      Monitoring results that exceeded AQO are shown in bold characters.

 

8.10        For Hong Kong Island side, there is also no EPD general air quality monitoring station located in the vicinity of the study area.  The nearest one would be the Central/Western monitoring station of which the average annual TSP level recorded at the recent five years (2006 –  2010) is 76.4μg/m3.

8.11        Central/Western monitoring station is located at Sai Ying Pun at the centre of the hinterland area.  The monitoring station is surrounded by mixture of commercial as well as densely populated residential areas and busy local traffic networks in all directions.  The TSP recorded at this station would largely be contributed by the vehicular emissions from the surrounding road network.   On the contrary, the study area of this Project at the Hong Kong Island side is a harbourfront location facing the Harbour to the north.  Lower TSP levels would be expected when wind is blowing in the prevailing north-easterly direction.  Given the different site characteristic of the study area and EPD’s monitoring station, recent monitoring data recorded at harbourfront locations by the environmental monitoring and audit (EM&A) programme for other designated project in close proximity to the study area are referred to for estimation of the background TSP level.

8.12        Central Reclamation Phase III (CRIII) is a designated project under the EIA Ordinance and its project site is located near the northern harbourfront of the Hong Kong Island similar to the environs of the study area under this Project at the Hong Kong Island side.   In accordance with the approved EM&A Manual[1] for CRIII, two air quality monitoring stations were set up to measure the TSP levels in the vicinity of the project site, one at the Chinese People’s Liberation Army Force Hong Kong Building (PLA) and the other at City Hall.  Hong Kong as a whole is characterized with northeast prevailing wind throughout the year.  Influence from the traffic emission impact is therefore relatively lower in most of the time at the harbourfront and the dust arising from CRIII is the dominant source. The site characteristic of this Project and CRIII are similar, the air quality monitoring data recorded by CRIII is therefore considered more appropriate to represent the background air quality concentration of this Project at the Hong Kong Island side. 

8.13        The air quality monitoring at PLA commenced in April 2005 and data of up to 5 years are available to represent the background air quality in the surrounding area.  Whereas the air quality monitoring at City Hall only commenced in March 2006 with less than 5 years available data at the time of preparation of this assessment and thus is not selected for background air quality estimation.

8.14        All the TSP monitoring data were recorded in accordance with the requirements stipulated in the EM&A Manual of CRIII and were reviewed and submitted as per the requirements of the corresponding environmental permit issued under the EIA Ordinance.  All the TSP levels were measured in accordance with the standard high volume sampling method set out in the Title 40 of the Code of Federal Regulations, Chapter 1 (Part 50), Appendix B.  Initial calibration of dust monitoring equipment was conducted upon installation and thereafter at bi-monthly intervals.  The transfer standard is traceable to the internationally recognised primary standard and was calibrated annually.  The calibration and air quality monitoring was conducted by independent environmental team and led by an environmental team leader.  The calibration data were also reviewed and validated by independent environmental checker.  The collected dust samples were analysed by a laboratory which had been inspected and audited by the independent environmental checker as per the EM&A Manual of CRIII Project to undertake the dust analysis.

8.15        Review of the detailed TSP monitoring results recorded at PLA was undertaken and it is observed that some unusually low TSP concentrations were measured on some days.  TSP comprises of suspended particulates of different size including respirable suspended particulates (RSP).  The background RSP level in Hong Kong is largely influenced by regional contribution, thus the spatial variation of RSP level over the Hong Kong territory is relatively small in general.  The TSP level recorded at PLA is considered as unusually low if the TSP value is lower than the RSP level recorded at EPD’s rural monitoring station at Tap Mun during the same monitoring day.  For the purpose of quality control, those unusually low TSP levels are discarded in the calculation of annual average TSP level for this study.

8.16        The TSP data recorded at PLA are considered as of acceptable quality and with sufficient valid data after discarding the unusually low TSP monitoring data.  The estimated background TSP concentration for the study area at Hong Kong Island side using the PLA monitoring results (2006 – 2010) is 73μg/m3.  The past TSP monitoring data recorded at PLA is attached in Appendix 8.1.

8.17        For the offsite works area in Shek O, there is no EPD general air quality monitoring station located in the vicinity of the study area. Since Shek O, in accordance with the Guidelines in Assessing the ‘TOTAL’ Air Quality Impacts and Annual Air Quality Monitoring Report, is categorized as rural area, the recent five years (2006 – 2010) annual average monitoring data recorded for EPD’s general air quality monitoring stations in rural areas are therefore taken to estimate the background concentration.  EPD’s rural general air quality monitoring stations considered in this assessment include Shatin, Tai Po and Tung Chung.  The background TSP concentrations adopted in this assessment for Shek O area is estimated as the mean of the annual average concentrations (2006 – 2010) recorded at these rural monitoring stations and is equal to 66.4µg/m3.

Air Sensitive Receivers

8.18        In accordance with Annex 12 of the EIAO-TM, any domestic premises, hotel, hostel, hospital, clinic, nursery, temporary housing accommodation, school, educational institution, office, factory, shop, shopping centre, place of public worship, library, court of law, sports stadium or performing arts centre are considered as air sensitive receivers (ASRs).  As stated in the EIA Study Brief, the boundary of the assessment area for air quality assessment should be 500m from the Project alignment and boundaries of all associated areas under the Project.  A total of 18 representative ASRs, which are considered to be most likely to be affected by the construction of the Project, have been identified for this assessment.  The selected representative ASRs are listed in Table 8.3 and their locations are illustrated in Figure Nos. NEX2213/C/331/ENS/M60/001 to NEX2213/C/331/ENS/M60/004.

8.19        The proposed alignment would generally be built by cut-and-cover methods, drill and blast, immersed tube (IMT) or soft ground Tunnel Boring Machines (TBMs).  For the cut-and-cover section, some of the associated construction works would be at ground level.  Whereas for IMT, TBM or drill-and-blast section, the works are mostly underground or underwater with minimal dust emission. 

8.20        The lowest assessment height was therefore taken as either at 1.5m above local ground level (AGL) which is the average height of the human breathing zone or at the lowest height where the air sensitive use of the respective ASR locates.  Higher assessment levels as shown in Table 8.3 were also selected for elevated ASRs to show the vertical variation of the pollutant concentrations.

Table 8.3           Representative Air Sensitive Receivers

ASRs

Description

Land Use

Distance from the nearest emission sources (m)

No. Of storey

Assessment Height

(m AGL)

Kowloon Side

HHA6

Harbour Plaza Metropolis

Hotel

50

11

1.5, 5, 10, 15 & 20

HHA7

Fire Service Headquarters

GIC

60

13

1.5, 5, 10, 15 & 20

HHA8

Hong Kong Coliseum (a)

GIC

35

1

10, 15 & 20

HHA9

Harbourfront Horizon (b)

Service Apartment

20

22

5, 10, 15 & 20

Hong Kong Side

CHA1

World Trade Centre (c)

Commercial

70

34

5, 10, 15 & 20

CHA2

Sino Plaza (c)

Commercial

35

33

5, 10, 15 & 20

EXA1

Causeway Centre Block A (c)

Residential

25

42

5, 10, 15 & 20

EXA2

Great Eagle centre (c)

Commercial

10

27

5, 10, 15 & 20

EXA3

Renaissance Harbour View Hotel (c)

Hotel

15

46

10[2], 15 & 20

EXA4

Pedestrian Plaza (b)

Recreation

25

NA

5

EXA5

Existing Harbour Road Sports Centre and Wan Chai Swimming Pool (would be demolished in 2015) (b)

Government/Institution/ Community

5

6

2, 5 & 10

EXA6

Wanchai Sports Ground

Government/Institution/ Community

20

NA

1.5

EXA7

New Harbour Road Sports Centre and Wan Chai Swimming Pool (would be in operation in 2015) (c)

Government/Institution/ Community

5

7

10, 15 & 20

ADA1

New G/IC site south and east of CITIC Tower

Government/Institution/ Community

160

20

1.5, 5, 10, 15 & 20

ADA2

Police Headquarters (Cain House)

Government/Institution/ Community

165

7

1.5, 5, 10, 15 & 20

ADA3

Admiralty Centre (c)

Commercial

320

25

5, 10, 15 & 20

ADA4

Police Headquarters (West Wing)

Government/Institution/ Community

300

42

1.5, 5, 10, 15 & 20

Off-site

TWA1

To Tei Wan Village

Residential

310

2

1.5

Notes:

(a)           Hong Kong Coliseum is sitting on the podium of HUH.  The tunnel construction works adjacent to this ASR will be carried out underneath the HUH podium.  As such, the lowest assessment height for this ASR is taken as 10m above the construction works.

(b)           The height of the lowest air sensitive use was selected as the lowest assessment height of the respective ASR.

(c)            The estimated lowest fresh air intake location was selected as the lowest assessment height of the respective ASR.

 

Potential Sources of Impact

8.21        The Project is an approximately 6km extension of the existing EAL from the HUH across the harbour to new EXH and ADM.  HUH, EXH and ADM would become integrated interchange stations with existing and planned lines.

8.22        The design and build of the new ADM and Hong Kong Park Ventilation Building would be carried out under the SIL(E) project, therefore, the construction activities for these structures (underground and foundation) will be assessed under the SIL(E) EIA. Based on the latest works programme, the construction of the Project would not be concurrent with the SIL(E).

8.23        Besides the construction of the railway alignment, the Project includes the construction of new stations, construction of plant rooms ventilation shafts, some demolition works and culvert/drain diversion.  In addition, barging point locations are proposed at Hung Hom Freight Pier on Kowloon side and Wan Chai Waterfront Promenade on Hong Kong Island side. 

8.24        Major construction works that would contribute to dust impacts would include surface works for the construction of tunnel, construction of superstructures including the new stations, plant rooms and ventilation shafts, as well as the operation of barging points.  The tentative working hours will be from 07:00 – 19:00 from Monday to Saturday for all works sites including barging points.  Locations of the works sites and barging points are illustrated in Figure Nos. NEX2213/C/331/ENS/M60/001 to NEX2213/C/331/ENS/M60/003.  The details of construction activities and potential emission sources are described in the following sections.

8.25        Alternative construction methods/phasing programme were described in Chapter 2 of this report.

Tunnel

8.26        The construction for tunnels at Hung Hom area would be generally carried out by cut-and-cover method near waterfront and Hung Hom Landfall.  The North Ventilation Building, Plant Rooms and Emergency Access (NOV) which is located to the south of the Hung Hom podium and above the SCL running tracks would also be constructed by cut-and-cover method.  In addition, the existing Kowloon Freight Building at south of HUH and the tip of the Hung Hom Freight Pier would need to be demolished to facilitate the tunnel construction.  The latter would be reprovisioned in situ as pile structures after the tunnel construction.

8.27        The cross-harbour tunnels would be constructed using IMT and the section of tunnels within the Causeway Bay Typhoon Shelter (CBTS) would be constructed by cut-and-cover method involving temporary reclamation.  The South Ventilation Shafts, Plant Rooms and Emergency Access (SOV) would also be constructed by cut-and-cover method.  Tunnels from the SOV to ADM would be constructed using TBM with a section between Hong Kong Convention and Exhibition Centre (HKCEC) by cut-and-cover method, which would be reclaimed under the Wan Chai Development Phase II (WDII) Project.  The ADM overrun would be constructed by drill-and-blast method.

8.28        For cross-harbour tunnel construction using IMT method, the excavated materials would be wet or the construction works would be carried out at seabed and no dust emission would be expected.

8.29        For the drill-and-blast section at ADM overrun tunnel and TBM at Causeway Bay, works would be performed entirely underground, except the shaft construction, and major open dust emission source is not anticipated.

8.30        For those sections using cut-and-cover method, construction would be conducted initially above ground for installation of a deck.  Once the deck is installed, majority of the construction activities would be underground below the deck.  Therefore, the major potential dust impacts above ground would be dust arising from excavation, material handlings and transportation of spoils on the paved haul road within the site.

8.31        During excavation and unloading of spoils, water spraying would be provided to alleviate potential dust emissions.  All the trucks would be equipped with a cover and the dusty materials would be well covered before leaving the works site area.  Therefore, adverse dust impact from the transportation of spoil would not be anticipated.  Wheel washing facilities would be provided at every designated vehicle exit point.  Since all vehicles would be washed at exit points and all trucks loaded with dusty materials would be covered entirely before leaving the works site, the dust nuisance from construction vehicle movement outside the works site is unlikely to be significant. 

8.32        As mentioned in Section 8.26, existing Kowloon Freight Building and the tip of the Hung Hom Freight Pier should be demolished before the construction of the tunnel.  However, dust arising from demolishing reinforced concrete structure would be limited, with the implementation of dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation, adverse dust impact would not be expected.

Adits & Shafts and Ventilation Shafts

8.33        There are adits and shafts to be built along the Project alignment for the operational tunnel ventilation.  These adits and shafts are also used during construction phase for providing access for delivery of tunnelling equipment and permanent material and the removal of spoil (for sections of Project alignment using TBM and drill-and-blast method).

8.34        The size of the construction area for each adit/shaft would be limited.  After site clearance and open-cut excavation at the surface area, the sheet piles/diaphragm wall would be installed.  Generally, the tracked crane would be used for mucking out.  Though mucking areas would not be fully enclosed, water spraying would be provided during excavation and unloading of spoils, to alleviate potential dust emissions.  All the trucks would be equipped with a cover and dusty materials would be well covered before leaving the mucking-out areas.  Moreover, as the excavation is carried out below sea level, the excavated materials would mostly be slurry with high moisture content.  Therefore, adverse dust impact from the transportation of spoil would not be anticipated.

8.35        An underground plant room, namely SOV, would be built by cut-and-cover method underneath the existing Police Officer’s Club (POC) which is adjacent to the Cross Harbour Tunnel and CBTS.  The existing POC facilities would be demolished to enable construction of the SOV and tunnel structure.  On completion of the SCL construction, the POC would be reconstructed at its current location and the SOV would be an integrated part of the reprovisioned POC.  A shaft would be installed on top of the SOV to support the tunnel operation.  The SOV is designed as simple reinforced concrete structure with rooms to house the ventilation fans and support systems.  Potential dust impact would be expected and would be assessed in this assessment.

8.36        An aboveground plant room, namely NOV would be built at Hung Hom area.  Some ventilation shafts would also be built at the EXH for the operational tunnel and station ventilation.  However, the construction areas for NOV and the ventilation shafts at EXH would be limited and are designed as reinforced concrete structures.  Adverse dust impacts arising from construction of ventilation buildings and ventilation shafts are not anticipated with the implementation of dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation.

SCL Protection Works and Minimum Protection Works undertaken by WDII and Central Wanchai Bypass (CWB)

8.37        In accordance with the latest construction programme, some construction works of SCL would be carried out at the CBTS temporary reclamation area under CWB project and the HKCEC reclamation area under WDII project.  These construction works would be carried out in advance and would not interface with this Project.

SCL Protection Works at CBTS

8.38        For the SCL Protection Works at CBTS, the construction works, which are to be undertaken by CWB project, would be advanced in 2012 and completed in 2013 before the commencement of this Project.  The potential air quality impact associated with the construction of the SCL Protection Works at CBTS was assessed and presented in its EIA report.  As concluded in its EIA report, with the implementation of the recommended mitigation measures as well as the dust suppression measures and good site practices stipulated in the Air Pollution Control (Construction Dust) Regulation, no adverse dust impact on the ASRs in the vicinity of the construction sites would be anticipated.

Entrustment works next to HKCEC Phase I

8.39        The entrustment work at reclamation area of HKCEC1 under WDII will also be carried out in advance in 2011/2012 for about half year by WDII project.  The associated potential air quality impact was assessed in a stand-alone Preliminary Environmental Report.  Works area of entrustment works would be around 0.1ha and would include construction of D-walls and excavation up to +2mPD for construction of top slab.  No additional excavation would be required for this protection works.

8.40        In view of the small scale and short-term nature (last for 6 months) of the entrustment works, dust generation from the excavation and backfilling works is considered limited.  Since the entrustment works is laid within the works area of the WDII project and the scale is limited, adverse cumulative dust impacts on nearby ASRs (e.g. HKCEC, Pedestrian Plaza, and HKCEC Extension) from the entrustment works and the construction of WDII project is not anticipated with the implementation of appropriate dust control measures.

Barging Point

8.41        There are two on- site barging points to be provided for this Project, one is located on Kowloon side at Hung Hom Freight Pier and the one on Hong Kong Island side would be proposed at Wan Chai Waterfront Promenade.

8.42        The barging point will operate for 12 hours a day (7:00 to 19:00) except the hoisting of Typhoon No.3 or above, Sundays and public holidays.  The spoil materials would be transported to the tipping halls of the barging points by trucks and then unloaded to the barges. 

8.43        The haul roads within the barging site would be all paved and provided with water spraying.  Vehicles would be required to pass through designated wheel washing facilities before leaving the barging facility.  Moreover, the dusty materials on the trucks would be well covered and flexible dust curtain would be provided at the loading points (from barging point to the barges).

On-site Mooring Site

8.44        A public mooring site is located at south-east side of CBTS for mooring of marine transports, such as boats, vessels and also for mooring yachts as temporary reprovisioning for the Royal Hong Kong Yacht Club.  No potential air quality impact would be expected.

Other Construction Works

8.45        There are some other associated construction works, including demolition works, pile removal, stormwater drain and culvert diversion.  The potential dust impacts from these activities are localized and the excavated areas are limited.  Adverse dust impacts from these construction works are not anticipated with the implementation of dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation.

Off-site Construction Works

8.46        An off-site construction works area has been identified and discussed in Table 8.4.  The location of the works site is shown in Figure No. NEX2213/C/331/ENS/M50/025.  The location of Shek O Casting Basin and its relationship with the nearby ASRs is shown in Figure No. NEX2213/C/331/ENS/M60/004.

Table 8.4           Off-site Construction Works Elements

Off-Sites

Location

Remark

Possible Representative ASR

IMT Casting Basin

Shek O Casting Basin

Works site are located at the previous Shek O Quarry.  The area is remote and assigned for previous quarrying activities (also used as IMT casting basin for Airport Rail Line in the past).

Making reference to the long-term quarrying activities in the past, no adverse air quality impact would be anticipated.

Besides, the concrete would be loaded from the truck into the barge in “wet” form, no dust would be generated in this process.  The potential dust impact would be only expected from the on-site haul road. 

To Tei Wan Village

A concrete batching plant would be proposed on site.  Potential dust impact associated with the operation of the plant is anticipated, but only daytime operation would be expected.

To Tei Wan Village

 

 

A barging point would be proposed on site at either the quay (northwest of the site) or the bund wall.  As the quay is located closer to the ASR as compared with the bund wall, unloading activities were assumed at the quay to represent a worst-case assumption.  Dusty activities will mainly be the unloading of spoils from the barge.  The spoils will then be transferred to the concrete batching plant through enclosed conveyor belt.  No adverse dust impact would be expected.

To Tei Wan Village

 

Cumulative Dust Impact from Other Concurrent Project

Kowloon Side

8.47        On Kowloon side, the Project would likely interface with SCL – Mong Kok East to Hung Hom Section [SCL (MKK – HUH)], Shatin to Central Link – Tai Wai to Hung Hom Section [SCL (TAW – HUH)], Kwun Tong Line Extension (KTE).  Any above ground construction activity arising from these concurrent projects that is located within 500m from the Project boundary would be examined in this assessment.

SCL (MKK – HUH)

8.48        SCL (MKK – HUH) branches out from the existing East Rail tracks from the tunnel portal near Oi Man Estate (Portal 1A) to the NOV in Hung Hom.  The construction of SCL (MKK – HUH) would be carried out by cut-and-cover method.  Construction would be conducted initially above ground for installation of slab.  Once the slab is installed, majority of the construction activities would be underground below the slab.  Therefore, the major potential dust impacts above ground would be dust arising from excavation, material handlings and transportation of spoils on the paved haul roads within the site.  The detailed assessment methodology is presented in the SCL (MKK – HUH) EIA report and it is also summarized in Appendix 8.2.

SCL (TAW – HUH)

8.49        The SCL (TAW – HUH) is an extension of Ma On Shan Line from the Tai Wai Station through the new stations in the east Kowloon, namely Diamond Hill, Kai Tak, To Kwa Wan, Ma Tau Wai, Ho Man Tin Stations and finally connecting the West Rail Line (WRL) at the HUH.  The section of the SCL (TAW – HUH) alignment at Hung Hom would be constructed by cut-and-cover method.  Potential dust impacts would be expected.  The detailed assessment methodology is presented in the SCL (TAW – HUH) EIA report and it is also summarized in Appendix 8.3.

KTE

8.50        The KTE alignment which branches out from the existing Yau Ma Tei Station to the new Ho Man Tin Station would be constructed by drill-and-blast and mine tunnelling methods.  The new Ho Man Tin Station would be constructed by cut-and-cover method and potential dust impacts would be expected.  The detailed assessment methodology is presented in the KTE EIA report and it is also summarized in Appendix 8.4.

Hong Kong Island Side

8.51        On Hong Kong Island side, the Project would likely interface with WDII and CWB. 

8.52        The major construction works for WDII and CWB Project would be the construction of trunk road and reclamation works.  The proposed trunk road runs from Central Interchange in Central Reclamation Phase I through the Central Reclamation Phase III, WDII and CWB project areas, and the Island Eastern Corridor Link (IECL) which provides connection from the eastern portal of the CWB to the IECL.

8.53        Any above ground construction activity arising from WDII and CWB that is located within 500m from the Project boundary would be examined in this assessment.  The assessment methodology extracted from the WDII and CWB EIA report is summarized in Appendix 8.5.

Shek O (Off-site)

8.54        During the construction phase of the Project, no concurrent project would be located within 500m of the Project works area at Shek O and hence cumulative dust impact would not be expected.

Assessment Methodology

8.55        Referring to the above sections, potential adverse dust impact would be expected from construction of cut-and-cover tunnel/station/adits/shafts, operation of the barging points and concrete batching plant.  Quantitative assessment is therefore conducted for these activities.  The potential dust emission sources considered in the assessment are shown in Figures No. NEX2213/C/331/ENS/M60/052 to NEX2213/C/331/ENS/M60/055 under Appendix 8.7.

8.56        Regarding construction of plant rooms and ventilation shafts, loading and unloading of spoils at the adits/shafts, no adverse dust impact at nearby sensitive receivers would be expected due to limited dusty construction activities.  Minor excavation works and spoil loading/unloading would all be undertaken within enclosed structure.  With the implementation of dust suppression measures as stipulated in Air Pollution Control (Construction Dust) Regulation, no adverse dust impacts would be expected from these construction activities.  Therefore, the potential dust impacts arising from these works areas are addressed qualitatively in the study.

8.57        Limited dust impact from unloading of spoils at the barging points would be expected with the installation of flexible dust curtain at the loading point, covering of the inactive temporary stockpiles areas, and water spraying on the active stockpiles area and haul roads.  However, the barging point at Hung Hom Freight Pier and Wan Chai Waterfront Promenade would operate concurrently with other dusty construction activities within the 500m study area.  Quantitative assessments are thus conducted to determine the cumulative dust impacts on the nearby ASRs.

Emission Inventory

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

8.59        According to USEPA AP-42[3], construction dust particles are grouped into various particle sizes. On Kowloon side, in order to maintain consistency in the model assumptions with the concurrent projects including SCL(TAW-HUH) and KTE, construction dust particles of five particle size classes were used.  Their size ranges are 1.25 mm, 3.75 mm, 7.5 mm, 12.5 mm, 22.5 mm, and the percentage of particles in each class was estimated to be 7%, 20%, 20%, 18% and 35%, respectively.

8.60        On Hong Kong Island,  the particle size ranges are 0.5 mm, 1.5 mm, 2.25 mm, 2.75 mm, 3.5 mm, 4.5 mm, 5.5 mm, 8 mm, 20 mm, and the percentage of particles in each class was estimated to be 4%, 7%, 4%, 3%, 7%, 5%, 4%, 17% and 49%, respectively.

8.61        Predicted dust emissions are based on emission factors from AP-42.  The major dusty construction activities for the Project to be considered in the modelling assessment include:

(A) Tunnel, Station, Plant Rooms and Ventilation Shafts Cut-and-Cover areas

-                 Excavation and material handlings within the construction site modelled as heavy construction activities

-                 Wind erosion of open active site

 

(B) Barging Points

-                 Transportation of the spoils to the enclosed tipping hall of Barging Point by trucks on the paved haul roads

-                 Unloading point to the barge

 

(C) Concrete Batching Plant at Shek O Casting Basin

-                 Unloading of aggregates to the receiving hopper

-                 Emissions from dust collectors at the top of the large capacity cement silos, cement/PFA silos and mixers

-                 Transporting of raw materials/products by trucks on the unpaved haul roads within the plant

8.62        According to the engineering design information, dust control measures have been incorporated into the design of the barging facilities, as presented in Table 8.5.  These dust control measures have also been taken into account in the assessment.

Table 8.5           Barging Facilities– Dust Emission Design Control Measures

Process

Description

Dust Emission Design Control Measures

Haul road within barging facilities

Transportation of spoils to the Barging Point

All road surfaces within the barging facilities would be paved and watering once along the haul road for every working hour would be provided.

 

Unloading of materials

Unloading of spoil materials

The unloading process would be undertaken within a 3-sided screen with top tipping hall.  Water spraying and flexible dust curtains would be provided at the discharge point for dust suppression.

 

Trucks

Vehicles leaving the barging facility

Vehicles would be required to pass through the wheel washing facilities provided at site exit.

 

 

8.63        The maximum production capacity of the concrete batching plant would be 250 m3 per hour and the total capacity of silo exceeds 50 tonnes and in which cement is handled.  The operation of the concrete batching plant is therefore classified as Specified Process (SP).  The Contractor should apply a SP license under APCO.  The requirements and mitigation measures stipulated in the Guidance Note on the Best Practicable Means for Cement Works (Concrete Batching Plant) BPM 3/2(93) should be followed and implemented.  According to the above Guidance Note, the design emission concentrations of the dust collectors for cement/ Pulverised Fuel Ash (PFA) silos and mixers of the concrete batching plant should not exceed 50 mg/m3.  The dust control measures as stipulated in the above Guidance Note have been incorporated into the design of the concrete batching plant as presented in Table 8.6.  These dust control measures have also been taken into account in the assessment.

Table 8.6           Concrete Batching Plant – Dust Emission Design Control Measures

Process

Description

Dust Emission Design Control Measures

Loading of raw materials

Unloading of aggregates from the tipper trucks to receiving hopper

The aggregates would be unloaded from the tipper trucks to the receiving hopper equipped with enclosures on 3 sides and top cover, and water spraying system.  Minimal dust emission would be generated during unloading of the raw materials.

 

 

Unloading of cement and PFA from tankers into the silo

The cement and PFA would be directly loaded into the silo via a flexible duct.  Dust collectors would be installed at cement/PFA silos, therefore, no dust emission would be expected.

 

Storage of raw materials

Storage of aggregates in overhead storage bins

The aggregates would be stored in fully enclosed overhead storage bins.  The top of overhead storage bins would be covered with cladding.  Water spraying system would be installed at the top of storage bins for watering the aggregates, and aggregates storage bins would be fully enclosed.  Thus, no dust emission would be expected.

Batching of raw materials

Weighing and batching of cementitious materials

The whole process of weighing and mixing would be performed in a fully enclosed environment.  The mixers would all equip with dust collectors, no dust emission would be expected.

Truck loading

Loading of concrete from mixer into transit mixer of a truck

The concrete would be directly loaded from the mixer into the transit mixer of a truck in “wet” form, no dust would be generated in this process.

Trucks

Tipper trucks and cement tankers leaving the Concrete Batching Plant

Haul road within the site is unpaved.  Wheel washing pit would be installed at the gate of the concrete batching plant.  Insignificant dust emission would be expected.

Unpaved haul road within the Concrete Batching Plant

Transportation of materials within the plant

Watering twice a day would be provided (standard mitigation measure as stipulated in the Air Pollution Control (Construction Dust) Regulation).

8.64        Due to the constrained size of the works sites and the tight construction programme, it will be necessary for active construction activities to be undertaken at multiple work faces spread across each site.  Therefore, it is not feasible to identify the exact location of individual dust emission source.  As such, for the purpose of predicting annual TSP concentrations, it is assumed that dust emissions would be distributed across the whole area of each site and the dust emission rates are estimated based on the annual average percentage active works area of each works site.  Based on the preliminary engineering design, the annual average active area is estimated to be 6% and would be assumed for predicting the annual average concentrations.  The justification for the percentage of annual average active area is presented in Appendix 8.6a.  However, for both the on-site and off-site barging points haul road areas, it is assumed that the barging point would be working at full capacity and a continuous use of the haul road throughout the construction period would be taken as a worst-case assumption.  Thus, 100% emission from the barging point haul road areas is assumed in the model.

8.65        Whereas for predicting hourly and daily average TSP levels, it is assumed that 20% of the total works area of each site would be active at any one time.  As mentioned above, it is not feasible to identify the exact locations of individual dust emission source.  As such, the dust modelling assessment has assumed that the dust emissions would be distributed across the whole area of each site to reasonably represent this mode of construction activities.

8.66        Based upon the above, works activities and plant would not be concentrated in certain areas of the site close to ASRs for an extended period of time during the construction period.  However, notwithstanding that such a scenario would not be expected to occur, a hypothetical Tier 1 screening test assuming 100% active area of construction site of the Project with mitigation measures in place has been undertaken.  It aims to highlight the hot spot locations where construction dust may potentially become an issue.  However, it should be emphasized that Tier 1 screening test is a hypothetical one which is very conservative and does not occur in reality.

8.67        The Tier 1 results have allowed a more focused Tier 2 assessment to be undertaken at the specific hot spot locations where TSP non-compliance is predicted under the Tier 1 screening test.  A focused Tier 2 assessment was undertaken whereby the % daily maximum active works areas, which is assumed to be 20% - 40%, for the Project are positioned closest to the potentially worst affected ASRs.  Same as for predicting annual average TSP levels, 100% emission from the barging point haul road areas is assumed in the model.  The Tier 2 assessment is also a very conservative approach as it assumed 20% - 40% active area of the Project would be located closest to the potentially worst affected ASRs at any one time and that the barging point would be working at full capacity throughout the construction period which is unlikely to occur in reality.  The justification for the percentage of hourly and daily average active area is presented in Appendix 8.6b.

8.68        The excavation rate, material handling rate, percentage active area, moisture content, silt content, number of trucks and truck speed are based on the preliminary engineering design.  The emission rate of identified pollutant sources are summarised in Table 8.7.  Detailed calculations of the emission factors are given in Appendix 8.7. 


Table 8.7           Emission Factors for Dusty Construction Activities

 

Emission Source

Activity

Emission Rate

Remarks

Kowloon Side

 

 

 

Tunnel Construction at Hung Hom Landfall

Heavy Construction Activities

E=2.69 Mg/hectare

/month of activity

 

*           100% area actively operating (for hourly and daily concentration prediction)

*           6% area actively operating (for annual concentration prediction)

*            AP42, Section 13.2.3

 

Wind Erosion

 

E=0.85Mg/hectare

/year

 

*           100% area actively operating (for hourly and daily concentration prediction)

*           6% area actively operating (for annual concentration prediction)

*             AP42, Section 11.9, Table 11.9.4

Hong Kong Island Side

Tunnel Construction and Construction of SOV / New EXH and Launching Shafts

(Cut-and-Cover Areas)

Heavy Construction Activities

E=2.69 Mg/hectare

/month of activity

 

*           100% area actively operating (for Tier 1 hourly and daily concentration prediction)

*           20% area actively operating (for Tier 2 hourly and daily concentration prediction)

*           6% area actively operating (for annual concentration prediction)

*             AP42, Section 13.2.3

 

Wind Erosion

 

E=0.85Mg/hectare

/year

 

*           100% area actively operating (for Tier 1 hourly and daily concentration prediction)

*           20% area actively operating (for Tier 2 hourly and daily concentration prediction)

*           6% area actively operating (for annual concentration prediction)

*             AP42, Section 11.9.4

Barging Point at Wan Chai Waterfront Promenade

Unloading of spoils to barge

E = k x (0.0016) x [(U/2.2)1.3 / (M/2)1.4]

*             AP-42, S13.2.4, particle size < 30 um, 1/95 ed

*             AP-42, Table 13.2.4-1, 1/95 ed

*             Handling capacity: 2500Mg/day

*             Number of berth: 1

 

Paved haul road –Transport the spoil from the stockpile to the Barging Point and potential temporary stockpile (Modelled as Heavy Construction)

 

E=2.69 Mg/hectare

/month of activity

 

*             100% area actively operating

*             AP42, Section 13.2.3

 

Shek O (Off-site)

Concrete Batching Plant at Shek O Casting Basin

Unloading of aggregates to the receiving hopper of concrete batching plant

E=0.0064lb/yd3

 

*             AP42 Section 11.12, (aggregate transfer)

*             Max. loading rate of aggregate = 250m3/hr

 

Dust collector for each cement/PFA silo/mixer

E=50mg/m3

 

*             Design emission concentration of 50mg/m3

*             Exhaust rate for dust collector: 1780m3/hr

*             Number of silos/mixer: 6

Shek O Casting Basin

Heavy Construction Activities

E=2.69 Mg/hectare

/month of activity

 

*           100% area actively operating (for Tier 1 hourly and daily concentration prediction)

*           40% area actively operating (for Tier 2 hourly and daily concentration prediction)

*           40% area actively operating (for annual concentration prediction)

*           AP42, Section 13.2.3

 

Shek O Casting Basin

Wind Erosion

(night time)

E=0.85Mg/hectare

/year

=8.086 x 10-7 g/m2/s

 

*           100% area actively operating (for Tier 1 hourly and daily concentration prediction)

*           40% area actively operating (for Tier 2 hourly and daily concentration prediction)

*           40% area actively operating (for annual concentration prediction)

*           AP42, Section 11.9.4

Barging Point at Shek O Casting Basin

Unloading of spoils to barge

E = k x (0.0016) x [(U/2.2)1.3 / (M/2)1.4]

*             AP-42, S13.2.4, particle size < 30 um, 1/95 ed

*             AP-42, Table 13.2.4-1, 1/95 ed

*             Handling capacity for each barging point: 4000Mg/day

*             Number of berth: 1

 

8.69        Twelve working hours per day on normal working days was assumed for the above-mentioned construction activities during 07:00 to 19:00 in the assessment.

8.70        According to the updated information presented in the Environmental Permit of WDII & CWB Project, the construction period of the whole WDII & CWB project is from 2009 to 2017.  It is expected that the construction of this Project would be only concurrently with the construction of WDII Project after 2013.  The hourly and daily dust impacts arising from the construction of WDII & CWB in mid 2013 to early 2014 (namely scenario 1 in this assessment), mid 2014 to early 2015 (namely scenario 2 in this assessment) and mid 2015 to 2017 (namely scenario 3 in this assessment) were predicted and presented in the approved WDII & CWB EIA Report. 

8.71        However, annual average TSP concentrations were not predicted in the WDII & CWB EIA.  The annual TSP impact is therefore assessed by assuming an annual average active area of 6% calculated based on the available construction programme and plant inventory of WDII & CWB EIA Report.  The justification for the percentage of annual average active area is presented in Appendix 8.6c. 

8.72        With reference to the proposed construction method of WDII and CWB, temporary seawall construction will be first conducted to enclose each phase of the temporary reclamation.  Installation of diaphragm wall on temporary reclamation land as well as any bulk filling will proceed behind the completed seawall.  After the temporary reclaimed land was formed, tunnel box construction by cut-and-cover method down to below water level will be conducted.  Then all construction works would be carried out below water level and adverse dust impact would not be anticipated.  Finally, the temporary reclamation will be removed after completion of all tunnel construction works.  According to the assumption made under WDII & CWB EIA, the maximum percentage of active construction works area is 50%, the remaining 50% of the works area is just exposed to air without any construction works.  Therefore, as the worst-case assumption, the annual exposed area is assumed to be 50% for predicting the annual concentrations.  Detailed calculations of the emission factors are presented in Appendix 8.5.  The major dusty construction activities during construction of WDII from year 2013 to 2017 which interfacing with the Project were extracted from WDII EIA Report Table 3.6 and its EP, EP-356/2009 as follows:

 

Table 8.8           Different Major Dust Generating Activities in the Worst Scenarios during Construction Phase of WDII

Activities

Scenario 1

(namely Scenario 4 in WDII EIA report)

Scenario 2

(namely Scenario 5 in WDII EIA report)

Scenario 3

(namely Scenario 6 in WDII EIA report)

1

TCBR3 – CWB Tunnel

TCBR3 – CWB Tunnel

TCBR4 – CWB Tunnel

2

TCBR4 – Filling

TCBR4 – CWB Tunnel

TPCWAW – CWB Tunnel

3

TPCWAW – CWB Tunnel

Slip Rd 8 & Victoria Park Reprovisioning

Realignment Hung Hing Road

4

WCR2 – Promenade

TPCWAW – CWB Tunnel

Rd P2 from Fleming Road to Marsh Road

5

WCR3 – Filling

WCR3 – CWB Tunnel

Mainline to IEC

6

WCR4 – Filling

WCR4 – CWB Tunnel

 

7

WCR4 – Drainage

HKCEC2E – Drainage

 

8

HKCEC2W – CWB Tunnel

HKCEC2W – Drainage

 

9

HKCEC3W – CWB Tunnel

HKCEC2E – CWB Tunnel

 

10

HKCEC3E – CWB Tunnel

HKCEC2W – CWB Tunnel

 

11

IEC Connection Work

HKCEC3E – CWB Tunnel

 

12

 

HKCEC3W – CWB Tunnel

 

 

8.73        According to the construction programme (Appendix 3.4), the major dusty activities of this Project which would be undertaken concurrently during the above three periods have been identified in order to conduct the cumulative impact assessment.  As the construction of this Project would be undertaken from mid 2013 to 2020, the worst assessment year during this period would be taken as the year having the maximum number of construction activities.  The concurrent major dusty construction activities during different worst construction periods are summarized below:

Table 8.9           Major Dust Generating Activities during Different Construction Periods

Period

Mid 2013 – Early 2014

Mid 2014 – Early 2015

Worst Assessment Year between Mid 2015 – 2020

Activities

Scenario 1

Scenario 2

Scenario 3

1

Barging point at Wan Chai Waterfront Promenade

Barging point at Wan Chai Waterfront Promenade

Barging point at Wan Chai Waterfront Promenade

2

Launching Shaft Construction at Convention Avenue

Launching Shaft Construction at Convention Avenue

Launching Shaft Construction at Convention Avenue

3

EXH Construction at PTI Area

EXH Construction at PTI Area

EXH Construction at PTI Area

4

 

EXH Construction at Wan Chai Sport Ground

EXH Construction at Wan Chai Sport Ground

5

 

Tunnel Construction West of EXH

Tunnel Construction West of EXH

6

 

SOV Construction

SOV Construction

7

 

 

Tunnel Construction at CBTS (outside breakwater)

8

 

 

Tunnel Construction at CBTS (inside breakwater)

9

 

 

EXH Station Construction at Harbour Road Sports Centre

10

 

 

EXH Station Construction at Fleming Road

 

Dispersion Modelling & Concentration Calculation

8.74        Fugitive Dust Model (FDM) (1993 version) was adopted to assess potential dust impact from the construction works.  The heights of 1.5m or the lowest air sensitive level, 5m, 10m, 15m and 20m above ground were adopted for the construction dust impact assessment.

8.75        Hourly meteorological data including wind speed, wind direction, air temperature and Pasquill stability class from the nearest Hong Kong Observatory weather station, Hong Kong Observatory Station, for the year 2008, were employed for the model run in Kowloon side.  Since no construction activities would occur on Sundays and public holidays, only wind erosion would be assumed for these days as well as for other non-working hours (19:00 to 07:00 of the following day) on normal working days.

8.76        Whereas, the worst case meteorological condition was used to predict the maximum hourly and daily average TSP concentrations at representative discrete ASRs in the vicinity of the construction sites at Hong Kong Island side. 

·                     Wind speed:                             1 m/s

·                     Wind direction:                          360 wind directions (1 degree resolution)

·                     Resolution:                               1°

·                     Stability class:                          D (daytime, 8:00-18:00) & F (night time, 18:00-8:00)

·                     Surface roughness:                   1m

·                     Mixing height:                           500 m

8.77        In order to calculate the cumulative pollutant concentrations from this Project and WDII & CWB project, the dispersion model was undertaken based on the above worst case meteorological conditions.  The cumulative pollutant concentrations at the ASRs under each specific wind direction were calculated by summing the results from the same scenario of this Project and  WDII & CWB project.  The highest pollutant concentrations at the ASRs amongst the 360 wind directions were identified as the worst predicted cumulative pollutant concentrations.

8.78        Daily TSP concentrations were calculated as follows:

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

8.79        For prediction of the annual TSP concentrations due to the Project, hourly meteorological data including wind speed, wind direction, air temperature and Pasquill stability class from the nearest Hong Kong Observatory weather station, Hong Kong Observatory Station, for the year 2008, were employed for the model run.

8.80        For prediction of the hourly, daily and annual TSP concentrations at Shek O, hourly meteorological data including wind speed, wind direction, air temperature and Pasquill stability class from the nearest Hong Kong Observatory weather station, Stanley Station, for the year 2008, were employed for the model run.

8.81        Since no construction activities would occur on Sundays and the public holidays, only wind erosion would be assumed for these days as well as for other non-working hours (19:00 to 0700 of the following day) on normal working days.

8.82        As mentioned in Section 8.9 - 8.17, the background TSP levels of 75.2 mg/m3 and 73.0 mg/m3 were adopted as the future TSP background concentration on Kowloon side and Hong Kong Island side respectively. 

8.83        For the off-site construction works at Shek O Casting Basin, the background TSP level of 66.4 mg/m3 was adopted as the future TSP background concentration.


Level of Uncertainty in the Assessment

8.84        The emission rates adopted in the construction dust impact assessment are in accordance with the USEPA AP-4), which had previously been applied in similar situations in other EIA studies in Hong Kong.

8.85        The Fugitive Dust Model (FDM) for construction dust impact assessment is an accepted model for use in assessing construction dust impacts with reference to EPD’s Guidelines on Choice of Models and Model Parameters.

8.86        There are some modelling limitations such as the accuracy of the plant inventory for the proposed construction works, sequences of construction activities, and assessment height limit of 20m in the adopted dust model.  Uncertainties in the assessment of impacts have been considered when drawing conclusion from the assessment.

Prediction and Evaluation of Impacts

Unmitigated Scenario

8.87        The predicted unmitigated cumulative maximum hourly, daily and annual average TSP concentrations at the representative ASRs are summarized in Tables 8.10 – 8.12  and detailed in Appendix 8.8.  The contour plots at 1.5m AGL are presented in Figure Nos. NEX2213/C/331/ENS/M60/063 - NEX2213/C/331/ENS/M60/077. 

Table 8.10         Predicted Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative Air Sensitive Receivers (Unmitigated) (Kowloon Side)

ASRs

Assessment Height (mAGL)

Cumulative Maximum TSP Concentrations in mg/m3

Hourly Average

24-hour Average

Annual Average

HHA6

1.5

648

149

76.6

 

5

612

144

76.5

 

10

426

125

76.2

 

15

236

106

76.0

 

20

181

97

75.8

HHA7

1.5

481

242

79.2

 

5

395

214

79.1

 

10

252

147

78.3

 

15

203

107

77.5

 

20

161

101

76.8

HHA8

10

394

127

75.9

 

15

254

108

75.8

 

20

194

96

75.7

HHA9

5

357

168

78.3

 

10

240

132

77.0

 

15

193

110

76.4

 

20

160

99

76.1

Note:      (1)   The background TSP level of 75.2 mg/m3 is included in the above results.

(2)   The hourly, daily and annual average TSP EIAO-TM/AQO criteria are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.

(3)   Boldfaced values represent the predicted TSP concentration exceeds the respective criteria.

 

Table 8.11         Predicted Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative Air Sensitive Receivers (Unmitigated) (Hong Kong Island Side)

ASRs

Assessment Height (mAGL)

Cumulative Maximum TSP Concentrations in mg/m3

Hourly Average

24-hour Average

Annual Average

CHA1

5

1357

634

77.0

 

10

800

432

75.8

 

15

582

293

75.0

 

20

446

227

74.4

CHA2

5

1774

809

78.4

 

10

919

494

76.2

 

15

645

322

75.1

 

20

486

224

74.4

EXA1

5

1605

668

79.0

 

10

896

480

76.5

 

15

635

334

75.4

 

20

440

243

74.7

EXA2

5

2355

1099

83.5

 

10

1154

601

78.2

 

15

716

375

76.2

 

20

479

260

75.3

EXA3

10

1408

734

81.4

 

15

892

459

78.2

 

20

591

311

76.5

EXA4

5

2099

684

81.4

EXA5

2

3118

1319

97.2

 

5

2206

864

85.6

 

10

1112

591

79.8

 

15

761

397

77.4

 

20

517

276

76.1

EXA6

1.5

5593

1884

89.5

EXA7

10

1298

676

78.1

 

15

798

412

76.2

 

20

514

273

75.2

ADA1

1.5

946

292

75.6

 

5

965

301

75.6

 

10

828

282

75.2

 

15

672

259

74.8

 

20

525

235

74.5

ADA2

1.5

763

265

75.3

 

5

789

275

75.3

 

10

697

260

74.9

 

15

586

242

74.5

 

20

470

222

74.2

ADA3

5

678

225

74.4

 

10

615

216

74.3

 

15

536

205

74.1

 

20

452

193

74.0

ADA4

1.5

619

220

74.5

 

5

647

229

74.5

 

10

587

220

74.4

 

15

510

208

74.1

 

20

428

195

73.9

Note:      (1)   The background TSP level of 73.0 mg/m3 is included in the above results.

(2)   The hourly, daily and annual average TSP EIAO-TM/AQO criteria are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.

(3)   Boldfaced values represent the predicted TSP concentration exceeds the respective criteria.

 

Table 8.12         Predicted Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative Air Sensitive Receivers (Unmitigated) (Shek O IMT Casting Basin (Off-site))

ASRs

Maximum Hourly Average TSP Concentrations in mg/m3

Maximum Daily Average TSP Concentrations in mg/m3

Annual Average TSP Concentrations in mg/m3

TWA1

(at 1.5m AGL)

1920

402

70.2

Note:      (1) The background TSP level of 66.4 mg/m3 has been included in the above results.

(2) The hourly average TSP EIAO-TM criterion: 500 mg/m3; the daily average TSP AQO criterion: 260 mg/m3; the annual average TSP AQO criterion: 80 mg/m3

(3)   Boldfaced values represent the predicted TSP concentration exceeds the respective criteria.

 

8.88        Based on the results shown in Tables 8.10 - 8.12 above, the predicted cumulative maximum hourly, daily and annual average TSP concentrations at most of the representative ASRs would exceed the criteria stipulated in EIAO-TM and AQO under unmitigated scenario.  Hence, proper dust mitigation measures should be implemented.

Recommended Air Quality Mitigation Measures

8.89        In order to minimise the construction dust impact, the following dust mitigation measures shall be implemented:

Ÿ     Watering once every working hour on active works areas, exposed areas and paved haul roads to reduce dust emission by 91.7%[4].  This dust suppression efficiency is derived based on the average haul road traffic, average evaporation rate and an assumed application intensity of 1.7 L/m2 for Kowloon side and 1.0 L/m2 for Hong Kong side once every working hour. Any potential dust impact and watering mitigation would be subject to the actual site condition.  For example, a construction activity that produces inherently wet conditions or in cases under rainy weather, the above water application intensity may not be unreservedly applied.  While the above watering frequency is to be followed, the extent of watering may vary depending on actual site conditions but should be sufficient to maintain an equivalent intensity of no less than 1.7 L/m2 for Kowloon side and 1.0 L/m2 for Hong Kong side to achieve the removal efficiency. The dust levels would be monitored and managed under an EM&A programme as specified in the EM&A Manual.

Ÿ     Enclosing the unloading process at barging point by a 3-sided screen with top tipping hall, provision of water spraying and flexible dust curtains to reduce dust emission by 50%[5].

8.90        In addition to the dust control measures described above, dust suppression measures stipulated in the Air Pollution Control (Construction Dust) Regulation and good site practices listed below shall be carried out to further minimize construction dust impact:

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

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

Ÿ     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.

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

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

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

Ÿ     Provision of wind shield and dust extraction units or similar dust mitigation measures at the loading area of barging point, 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.

Ÿ     Provision of not less than 2.4m high hoarding from ground level along site boundary where adjoins a road, streets or other accessible to the public except for a site entrance or exit.

Ÿ     Imposition of speed controls for vehicles on site haul roads.

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

Ÿ     Every stock of more than 20 bags of cement or dry pulverised fuel ash (PFA) should be covered entirely by impervious sheeting or placed in an area sheltered on the top and the 3 sides.

Ÿ     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.

Mitigated Scenario

Kowloon Side

8.91        The predicted mitigated cumulative maximum hourly, daily and annual average TSP concentrations at the representative ASRs during construction are summarized in Table 8.13.

Table 8.13         Predicted Cumulative Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative Air Sensitive Receivers (Mitigated) (Kowloon Side)

ASRs

Assessment Height (mAGL)

Cumulative Maximum TSP Concentrations in mg/m3

Hourly Average

24-hour Average

Annual Average

HHA6

1.5

213

113

76.5

 

5

242

113

76.4

 

10

231

108

76.1

 

15

153

102

75.9

 

20

143

97

75.7

HHA7

1.5

195

112

78.1

 

5

192

111

78.0

 

10

178

108

77.5

 

15

163

104

77.0

 

20

153

101

76.6

HHA8

10

196

104

75.9

 

15

161

100

75.7

 

20

145

96

75.6

HHA9

5

201

105

77.9

 

10

168

102

76.7

 

15

143

98

76.2

 

20

137

95

75.9

Note:      (1)   The background TSP level of 75.2 mg/m3 is included in the above results.

(2)   The hourly, daily and annual average TSP EIAO-TM/AQO criteria are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.

 

8.92        Based on the results shown in Table 8.13, the cumulative maximum hourly, daily and annual average TSP levels at all ASRs would comply with the criteria stipulated in EIAO-TM and AQO after implementation of the proposed dust mitigation measures.  The worst-hit level would be at 1.5m AGL at most ASRs.  The contour plots of cumulative maximum hourly, daily and annual average TSP concentrations at 1.5m AGL are presented in Figure Nos. NEX2213/C/331/ENS/M60/005 - NEX2213/C/331/ENS/M60/007.  As there is no air sensitive use at the ground level of Harbourfront Horizon (HHA9), the highest cumulative  TSP concentration is predicted at 5mAGL.  Contour plots of cumulative maximum hourly, daily and annual average TSP concentration at HHA9 (5mAGL) is presented in Figure No. NEX2213/C/331/ENS/M60/008, NEX2213/C/331/ENS/M60/061 - 062.  Some exceedance of hourly, daily and annual average TSP concentrations were predicted at the north of the HUH and the freight pier in the contour plots, however, there is no air sensitive use at these areas and no adverse impact is anticipated.

Hong Kong Island Side

8.93        The predicted mitigated cumulative maximum hourly and daily average TSP concentrations amongst the three assessment scenarios of Tier 1 screening test at the representative ASRs during construction are summarized in Tables 8.14 – 8.15.  The detailed assessment results are presented in Appendix 8.8.  The Tier 1 contour plots of cumulative maximum hourly and daily average TSP concentrations at 1.5m AGL are presented in Figure Nos. NEX2213/C/331/ENS/M60/009 - NEX2213/C/331/ENS/M60/014.

Table 8.14         Predicted Cumulative Maximum Hourly Average TSP Concentrations at Representative Air Sensitive Receivers (Tier 1 – Mitigated) (Hong Kong Island Side)

ASRs

Cumulative Maximum Hourly Average TSP Concentrations in mg/m3

1.5m AGL

5m AGL

10m AGL

15m AGL

20m AGL

CHA1

NA

210

196

178

159

CHA2

NA

214

166

155

145

EXA1

NA

269

227

190

163

EXA2

NA

357

240

195

164

EXA3

NA

NA

311

237

185

EXA4

NA

365

NA

NA

NA

EXA5

429

388

318

252

202

EXA6

533

NA

NA

NA

NA

EXA7

NA

NA

191

142

124

ADA1

203

207

194

179

164

ADA2

169

171

161

149

139

ADA3

NA

154

150

145

139

ADA4

141

144

139

134

128

Notes:    (1)   The background TSP level of 73.0 mg/m3 is included in the above results.

(2)   The hourly average TSP EIAO-TM criterion is 500 mg/m3.

(3)   Boldfaced values represent the predicted TSP concentration exceeds the respective criteria.

(4)   The lowest sensitive level of EXA5 is 2m AGL.

Table 8.15         Predicted Cumulative Maximum Daily Average TSP Concentrations at Representative Air Sensitive Receivers (Tier 1 – Mitigated) (Hong Kong Island Side)

ASRs

Cumulative Maximum Daily Average TSP Concentrations in mg/m3

1.5m AGL

5m AGL

10m AGL

15m AGL

20m AGL

CHA1

NA

147

130

121

112

CHA2

NA

146

122

113

107

EXA1

NA

175

147

127

114

EXA2

NA

211

149

129

114

EXA3

NA

NA

182

145

122

EXA4

NA

223

NA

NA

NA

EXA5

261

238

191

156

131

EXA6

275

NA

NA

NA

NA

EXA7

NA

NA

136

107

97

ADA1

141

142

135

126

118

ADA2

122

123

118

111

105

ADA3

NA

115

113

110

106

ADA4

108

110

107

104

100

Note:      (1)   The background TSP level of 73.0 mg/m3 is included in the above results.

(2)   The daily average TSP AQO criterion is 260 mg/m3.

(3)   Boldfaced values represent the predicted TSP concentration exceeds the respective criteria.

(4)   The lowest sensitive level of EXA5 is 2m AGL.

 

8.94        Based on the results of the Tier 1 screening test, the predicted TSP levels at the ASRs along Wanchai harbourfront between Marsh Road and Fleming Road (EXA5 and EXA6) would exceed the respective criteria.  These ASRs where TSP non-compliance was predicted under the Tier 1 screening test were selected to undergo the Tier 2 assessment.  Although the contour plot presented in Figure Nos. NEX2213/C/331/ENS/M60/009 – NEX2213/C/331/ENS/M60/014 showed exceedance of cumulative hourly and daily average TSP concentrations at EXA2, EXA3, EXA4 and EXA7 at 1.5m AGL, EXA2, EXA3 and EXA7 are commercial, hotel and GIC use with central air conditioning and their fresh air intake locations are at 10m AGL; whereas EXA4 is recreation use with the lowest air sensitive level is at 5m AGL.  In other words, there is no air sensitive use identified at the predicted exceedance areas at 1.5mAGL of EXA2, EXA3, EXA4 and EXA7 and adverse construction dust impacts at these ASRs were therefore not anticipated.

8.95        The assessment results of Tier 2 test are summarized in Tables 8.16 – 8.17.  The Tier 2 contour plots of cumulative maximum hourly and daily average TSP concentrations at 1.5m AGL for scenarios 1 – 3 are presented in Figure Nos. NEX2213/C/331/ENS/M60/015 - NEX2213/C/331/ENS/M60/020.

Table 8.16         Predicted Cumulative Maximum Hourly Average TSP Concentrations at Representative Air Sensitive Receivers (Tier 2 – Mitigated) (Hong Kong Island Side)

ASRs

Cumulative Maximum Hourly Average TSP Concentrations in mg/m3

1.5m AGL

5m AGL

10m AGL

15m AGL

20m AGL

EXA5

420

374

290

229

184

EXA6

341

NA

NA

NA

NA

Note:      (1)   The background TSP level of 73.0 mg/m3 is included in the above results.

(2)   The hourly average TSP EIAO-TM criterion is 500 mg/m3.

(3)   The lowest sensitive level of EXA5 is 2m AGL.

 

Table 8.17         Predicted Cumulative Maximum Daily Average TSP Concentrations at Representative Air Sensitive Receivers (Tier 2 – Mitigated) (Hong Kong Island Side)

ASRs

Cumulative Maximum Daily Average TSP Concentrations in mg/m3

1.5m AGL

5m AGL

10m AGL

15m AGL

20m AGL

EXA5

239

213

171

142

122

EXA6

206

NA

NA

NA

NA

Note:      (1)   The background TSP level of 73.0 mg/m3 is included in the above results.

(2)   The daily average TSP AQO criterion is 260 mg/m3.

(3)   The lowest sensitive level of EXA5 is 2m AGL.

 

8.96        Based on the results of the Tier 2 assessment, the cumulative maximum hourly and daily average TSP at all ASRs located within the hot spot area would comply with the criteria in EIAO-TM and AQO.

8.97        The cumulative maximum annual average TSP concentrations amongst the three assessment scenarios at the representative ASRs are predicted and presented in Table 8.18.  The detailed assessment results are presented in Appendix 8.8.

Table 8.18         Predicted Cumulative Annual Average TSP Concentrations at Representative Air Sensitive Receivers (Mitigated) (Hong Kong Island Side)

ASRs

Cumulative Annual Average TSP Concentrations in mg/m3

1.5m AGL

5m AGL

10m AGL

15m AGL

20m AGL

CHA1

NA

74.7

74.3

73.9

73.6

CHA2

NA

74.5

74.1

73.8

73.6

EXA1

NA

74.6

74.1

73.7

73.5

EXA2

NA

76.7

74.8

74.1

73.7

EXA3

NA

NA

75.8

74.7

74.1

EXA4

NA

77.0

NA

NA

NA

EXA5

78.1

76.4

75.0

74.4

74.0

EXA6

77.4

NA

NA

NA

NA

EXA7

NA

NA

74.0

73.6

73.4

ADA1

74.7

74.6

74.3

74.0

73.7

ADA2

74.4

74.4

74.1

73.8

73.6

ADA3

NA

73.8

73.7

73.6

73.5

ADA4

73.9

73.9

73.8

73.6

73.5

Note:      (1)   The background TSP level of 73.0 mg/m3 is included in the above results.

(2)   The annual average TSP AQO criterion is 80 mg/m3.

(3)   Boldfaced values represent the predicted TSP concentration exceeds the respective criteria.

(4)   The lowest sensitive level of EXA5 is 2m AGL.

 

8.98        Based on the results shown in Table 8.18, the cumulative annual average TSP levels at all ASRs would comply with the AQO after implementation of the proposed dust mitigation measures.  The worst-hit level would be predicted at 1.5m AGL and 5m AGL.  The contour plots of cumulative annual average TSP concentrations at 1.5m AGL and 5m AGL for scenarios 1 – 3 are presented in Figure Nos. NEX2213/C/331/ENS/M60/021 – NEX2213/C/331/ENS/M60/026.  Marginal exceedances of annual average TSP concentrations at 1.5m AGL are predicted at part of the buildings of Renaissance Harbour View Hotel and Hong Kong Convention & Exhibition Centre in the contour plots, the buildings of Renaissance Harbour View Hotel and Hong Kong Convention & Exhibition Centre are provided with central air conditioning and there are no fresh air intake at these areas, i.e. no air sensitive areas within the exceedance areas.  Some exceedances of annual average TSP concentrations at both 1.5m AGL and 5m AGL are predicted at the vicinity of Wanchai Harbourfront area and Causeway Bay Typhoon Shelter in the contour plots, however, there is no air sensitive use at these areas and some are in most case transient and no adverse impact is anticipated.  The existing Harbour Road Sports Centre and Wan Chai Swimming Pool would be demolished and in operation at south of its original location, i.e. EXA7.  The new Harbour Road Sports Centre and Wan Chai Swimming Pool will be provided with central air conditioning.  Exceedances of annual average TSP concentrations at 1.5m AGL are predicted at the existing location of existing Harbour Road Sports Centre and Wan Chai Swimming Pool in contour plot of scenario 3, however, the existing Harbour Road Sports Centre and Wan Chai Swimming Pool will be demolished at that time, and hence no air sensitive areas are located within the exceedance areas.

Shek O IMT Casting Basin (Off-site)

8.99        The predicted mitigated maximum hourly and daily average TSP concentrations of Tier 1 screening test and annual average TSP concentration at the representative ASR during construction are summarized in Table 8.19. 

8.100      Based on the results, the predicted mitigated annual average TSP concentration at the representative ASR would comply with the AQO.  However, the predicted mitigated maximum hourly average TSP concentration of the Tier 1 screening test would exceed the EIAO-TM criteria.  A focused Tier 2 assessment was thus undertaken.  The predicted mitigated maximum hourly and daily average TSP concentrations of the Tier 2 assessment at the representative ASR during construction are summarized in Table 8.19.

8.101      Based on the results of Tier 2 testing, hourly and daily average TSP at the representative ASR would comply with the criteria in EIAO-TM and AQO.  As there is only one ASR identified within the assessment boundary, contour of Tier 1 testing for screening purpose is not necessary.  The contour plots of maximum hourly, daily (Tier 2 Assessment) and annual average TSP concentrations at 1.5m AGL are shown in Figure Nos. NEX2213/C/331/ENS/M60/027 – NEX2213/C/331/ENS/M60/029. 

Table 8.19         Predicted Maximum Hourly, Daily and Annual Average TSP Concentrations at Representative Air Sensitive Receivers (Mitigated)

ASRs

Maximum TSP Concentrations in mg/m3

Hourly Average

Daily Average

Annual Average

 

Tier 1

Tier 2

Tier 1

Tier 2

TWA1

(at 1.5m AGL)

532

358

150

118

67.4

Note:      (1)   The background TSP level of 66.4 mg/m3 is included in the above results.

(2)   The hourly, daily and annual average TSP EIAO-TM/AQO criteria are 500 mg/m3, 260 mg/m3 and 80 mg/m3 respectively.

(3)   Boldfaced value represents the predicted TSP concentration exceeds the respective criteria.

 

Evaluation of Residual Impacts

8.102      With the implementation of the mitigation measures as stipulated in the Air Pollution Control (Construction Dust) Regulation together with the recommended dust control measures and good site practices, no adverse residual impact would be expected on both Kowloon and Hong Kong Island sides.

Shek O IMT Casting Basin (Off-site)

8.103      The operation of the concrete batching plant is classified as a SP.  The Contractor should apply a SP license under APCO before operation.  Suitable mitigation measures stipulated in the Guidance Note on the Best Practicable Means for Cement Works (Concrete Batching Plant) BPM 3/2(93) should be followed and implemented. 

8.104      For the rest of the casting basin, with the implementation of the mitigation measures as stipulated in the Air Pollution Control (Construction Dust) Regulation together with the recommended dust control measures and good site practices, the predicted dust impact at ASRs would comply with the hourly, daily and annual TSP criteria in the EIAO-TM and AQO.

Environmental Monitoring and Audit Requirements

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

Conclusion

8.106      Potential air quality impacts from the construction works of the Project would mainly be related to construction dust from excavation, materials handling, spoil removal and wind erosion.  With the implementation of mitigation measures specified in the Air Pollution Control (Construction Dust) Regulation together with the recommended dust suppression measures, good site practices, and EM&A programme, the predicted dust impact at ASRs would comply with the hourly, daily and annual TSP criteria in the EIAO-TM and AQO.  No adverse residual impact is anticipated.

 


[1]  Territory Development Department (July 2001). Central Reclamation, Phase III Studies, Site Investigation, Design and Construction, Environmental Monitoring and Audit Manual  

 

[2] Maunsell Consultants Asia Ltd, Environmental Impact Assessment Report (Hong Kong Convention and Exhibition Centre, Atrium Link Extension), March 2006

[3] USEPA Compilation of Air Pollutant Emission Factors (AP-42), Appendix B.2, Page B.2-13

[4] USEPA, AP-42, “Control of Open Fugitive Dust Sources”.

[5] USEPA AP-42, “Control Techniques for Particulate Emission for Stationary Sources Volume 2”.  It states that watering alone would reduce the dust emission by 50%.  However, the unloading facilities is enclosed by a 3-side screen with top, addition dust removal efficiency is expected.  Thus, it is a very conservative assumption.