6. Air Quality Assessment

6.1 Introduction

6.1.1 The potential air quality impacts associated with the construction and operation of the proposed Project are assessed according to the requirements stipulated in Section 3.4.1 of the Environmental Impact Assessment Study Brief (ESB-070/2001) and presented in the following section. The major components of the Project are described in detail in Chapter 2.

6.1.2 The proposed preferred alignment of the Project, comprising a tunnel section and above ground (intake shafts and portals), will cover areas where existing and future residential development will be located. There is potential for residents to be affected by air quality impacts during the construction stage.

6.1.3 This section presents an assessment of air quality impact associated with the construction and operation of the Project. As the proposed tunnel section will be constructed using a TBM (tunnel boring machine), limited construction nuisance is expected. If appropriate mitigation measures are not followed and implemented, it will result in potential dust nuisance due to the proximity to nearby sensitive receivers. Higher impacts are expected at both portals as they are two main discharge locations for the excavated material and temporary storage before disposal. The air quality impacts due to the operation of the Project are considered to be minor.

6.1.4 Odour is not expected to be an issue since the stream bed sediments will be left in place and are unlikely to be contaminated as there are no known sources of effluents being discharged into these streams.

6.2 Air Quality Assessment Criteria

6.2.1 The principal legislation regulating air emissions in Hong Kong is the Air Pollution Control Ordinance (APCO) [Cap 311] and its subsidiary regulations. Ten air control zones, covering the entire HKSAR, have been declared under APCO. A set of Air Quality Objectives (AQOs) applicable to all air control zones have also been established. The AQOs for hourly, daily and annual concentrations of four major pollutants are shown in Table 6.1.

Table 6.1

Hong Kong Air Quality Objectives (AQOs)

Pollutants	Concentration in Micrograms per Cubic Meters (µg/m^3) Averaging Time
	1 hour^A	24 hour^B	1 year^C
Nitrogen Dioxide (NO2)	300	150	80
Sulphur Dioxide (SO2)	800	350	80
Total Suspended Particulates (TSP)	500^E	260	80
Respirable Suspended Particulates (RSP)^D	--	180	55

Notes: Concentrations measured at 298K (25°C) and 101.325 kPa (one atmosphere)

^A 1 hour criteria not to be exceeded more than 3 times per year.

^B 24 hour criteria not to be exceeded more than once per year.

^C Arithmetic means.

^D Respirable suspended particulates means suspended particulates in air with a nominal aerodynamic diameter of 10 micrometer (µm) or smaller

^E This control limit is a criterion listed in 1.1(b) Annex 4 of the TM on EIA Process for evaluating construction dust assessment.

6.3 Air Sensitive Receivers

6.3.1 Air sensitive receivers (ASRs) of the development include any existing or planned residential areas, schools and parks etc in the vicinity of the development including residents of development itself. Potential representative ASRs outside of the development area have been identified from location plans and the information of tentative future development plans.

6.3.2 The representative ASRs that are outside the proposed development for use in the construction phase assessment are mainly high-rise residential building and schools. They are listed in Table 6.2 and shown in Figures 5.1-5.32 (Noise chapter).

Table 6.2

Details of Representative Air Sensitive Receivers

ASR No.	Figure no.	Descriptions	Status	Approximate distance to RASRs (m)
Eastern Portal	5.1
EP/1		Blk B Lai Sing Court	Residential	40
EP/2		Future Residential Development (Tower 1, The Legend)	Residential	10
EP/3		True Light Middle School of Hong Kong	School	30
Western Portal	5.2
WP/1		Point Breeze	Residential	140
WP/2		Aegean Terrace	Residential	80
Intake shafts B2(P)	5.3
B2(P)/1		Borrett Mansions	Residential	32
B2(P)/2		Carmel School	School	73
B2(P)/3		Glory Mansion	Residential	29
B2(P)/4		Grand House	Residential	33
Intake shafts BR3(P)	5.4
BR3(P)/1		Greenville Garden Block D	Residential	66
Intake shafts BR4(P)	5.5
BR4(P)/1		Kennedy Court	Residential	92
BR4(P)/2		St. James' Primary School	School	122
BR4(P)/3		Grandview Tower	Residential	111
Intake shafts BR5(P)	5.6
BR5(P)/1		Sakura Court	Residential	75
BR5(P)/2		Camelot Height	Residential	68
BR5(P)/3		HK Tang King Po College	School	123
Intake shafts BR6(P)	5.7
BR6(P)/1		16 Caronia	Residential	12
BR6(P)/2		Man Yuen Garden	Residential	39
BR6(P)/3		15 Carionia	Residential	75
Intake shafts BR7(P)	5.7
BR7(P)/1		16 Caronia	Residential	12
BR7(P)/2		15 Caronia	Residential	15
BR7(P)/3		12 B Bowen Road	Residential	53
BR7(P)/4		Monticello	Residential	60
BR7(P)/5		Man Yuen Garden	Residential	72
Intake shafts DG1(P)	5.8
DG1(P)/1		Rosaryhill School	School	54
DG1(P)/2		Blk C Villa Monte Rosa	Residential	29
DG1(P)/3		Evergreen Villa	Residential	51
Intake shafts E5(A)(P)	5.9
E5(A)(P)/1		Buddist Li Ka Shing Care & Attention Home for the Elderly	Elderly Home	5
E5(A)(P)/2		Blk 10, 135 Tai Hang Road	Residential	20
E5(A)(P)/4		Blk 10, 135 Tai Hang Road	Residential	23
Intake shafts E5(B)(P)	5.9
E5(B)(P)/1		Blk 9 Aurizon	Residential	21
E5(B)(P)/2		Blk 1 Cavendish Heights	Residential	15
Intake shafts E7(P)	5.10
E7(P)/1		Marymount Secondary School	School	8
E7(P)/2		French International School	School	77
E7(P)/3		117 Blue Pool Road	Residential	2
E7(P)/4		Blk J Villa Dorada	Residential	24
E7(P)/5		Blk 1 Green Lane Court	Residential	24
Intake shafts GL1(P)	5.11
GL1(P)/1		Green Lane Hall	Residential	20
Intake shafts HKU(P)	5.12
HKU1(P)/1		WSD Staff Quarters	Residential	36
Intake shafts HR	5.13
HR1/1		Shuk Yuen Terrace	Residential	39
HR1/2		16-20 Broom Road	Residential	23
Intake shafts M3(P)	5.14
M3(P)/1		May Fair	Residential	45
Intake shafts MA13(P)&MA14(P)	5.15
MA13(P) & MA14(P)/1		The Harbour View	Residential	17
MA13(P) & MA14(P)/2		Magazine Gap Towers	Residential	26
MA13(P) & MA14(P)/3		Magazine Heights	Residential	41
Intake shafts MA15(P)	5.15
MA15(P)/1		The Harbour View	Residential	9
MA15(P)/2		Magazine Gap Towers	Residential	86
MA15(P)/3		Rose Gardens	Residential	38
MA15(P)/4		Magazine Court	Residential	66
Intake shafts MA17(P)	5.16
MA17(P)/1		Blk A Grenville House	Residential	42
MA17(P)/2		Magazine Court	Residential	45
MA17(P)/3		Rose Gardens	Residential	85
Intake shafts MB16(P)	5.17
MB16/1		Clement Court	Residential	15
MB16/2		81 Perkins Road	Residential	20
MB16/3		83 Perkins Road	Residential	20
Intake shafts MBD2	5.18
MBD2/1		Amber Lodge	Residential	15
Intake shafts P5(P)	5.19
P5(P)/1		24 Po Shan Road	Residential	7
P5(P)/2		23 Po Shan Road	Residential	38
P5(P)/3		Haddon Court	Residential	50
Intake shafts PFLR(P)	5.20
PFLR(P)/1		Honey Court	Residential	14
PFLR(P)/2		Pokfulam Heights	Residential	19
Intake shafts RR1(P)	5.21
RR1(P)/1		Primrose Court	Residential	15
RR1(P)/2		Scenic Heights	Residential	21
RR1(P)/3		Ying Wa Girl's School	School	60
RR1(P)/4		Peaksville Court	Residential	29
Intake shafts THR2(P)	5.22
THR2(P)/1		Hong Chi Lions Morninghill School	School	7.5
THR2(P)/2		Hong Kong Japanese School	School	30
THR2(P)/3		Wan Chui Chuen	Residential	12
THR2(P)/4		Marymount Primary School	School	46
Intake shafts TP4(P)	5.23
TP4(P)/1		Tregunter Tower 1	Residential	32
TP4(P)/2		Tregunter Tower 2	Residential	26
Intake shafts TP5(P)	5.23
TP5(P)/1		Tavistock II	Residential	50
Intake shafts TP789(P)	5.24
TP789(P)/1		Tavistock	Residential	42
TP789(P)/2		Branksome	Residential	45
Intake shafts WO(P)	5.25
WO(P)/1		Sir Ellis Kadoorie Secondary School (Edward Hall)	School	18
WO(P)/2		Goodview Garden	Residential	25
WO(P)/3		Kui Yuen	Residential	30
Intake shafts W1(P)	5.26
W1(P)/1		74 Bamboo Grove	Residential	60
W1(P)/2		Blk B Merry Garden	Residential	25
W1(P)/3		St James's Primary School	School	64
W1(P)/4		Caine Terrace	Residential	18
Intake shafts W3(P)	5.27
W3(P)/1		Regent on the Park	Residential	63
W3(P)/2		Carmel School	School	158
W3(P)/3		Green Villa	Residential	95
Intake shafts W5(P)	5.28
W5(P)/1		Raimondi College	School	6
W5(P)/2		Raimondi Primary School	School	8
W5(P)/3		Caritas House	Residential	14
W5(P)/4		Canossa Hospital	Hospital	70
Intake shafts W8(P)	5.29
W8/1		Blk1, 80 Robinson Road	Residential	5
W8/2		Bonham Court	Residential	8
W8/3		Hong Kong Institute of Technology	School	1
Intake shafts W10(P)	5.30
W10/1		Future Residential Development	Residential	17
W10/2		Blk 2 Po Shan Rd	Residential	18
W10/3		University Lodge	School	51
W10/4		Blk A-B University Heights	Residential	38
Intake shafts W11(P)	5.31
W11(P)/1		17 Hatton Road	Residential	29
W11/(P)/2		Block B Hatton Place	Residential	56
Intake shafts W12(P)	5.32
W12(P)/1		Sylvanbrook	Residential	4
W12(P)/2		94A Pok Fu Lam Road	Residential	2
W12(P)/3		Blk A La Clare Mansion	Residential	27

6.4 Baseline Air Quality

Meteorology and Topography

6.4.1 The Study Area is situated in the northwest of Hong Kong Island. It comprises the fringes of the urban area and Country Parks. The project area is surrounded by series of hills, they are Jardine’s Lookout, Mount Nicholson, Mount Cameron, Wan Chai Gap, Mount Gough and Victoria Peak with peaks ranging from 300 m to 550 m.

6.4.2 Figures 6.1 a to d illustrates the wind conditions at North Point, Central Plaza, Star Ferry Central and Green Island of Hong Kong Observatory in year 2002 which are close to the Project and will be taken as an indication of the conditions. Most of time, dominant wind directions are come from East and Northeast directions. The wind pattern characteristic is the result of blocking effect of hills over western parts of the New Territories and Hong Kong Island. Topographic barriers also create eddies that change the direction and speed of the air.

Existing Conditions

6.4.3 EPD latest data from the air quality monitoring station at Central/Western has been used to estimate the ambient air quality of the Project. According to Air Quality in Hong Kong (EPD, 2000, 01 & 02), the concentration levels of the NO₂, SO₂, TSP and RSP for Central/Western Station during 2000-02 are shown in Table 6.3.

Table 6.3

Air Pollutants Maximum Concentrations at Central/Western

EPD Air Quality Monitoring Station (2000-2002)

Pollutant	Averaging Time	AQO (µg/m³)	2002 (µg/m³)	2001 (µg/m³)	2000 (µg/m³)
Sulphur Dioxide - SO2	1 hour	800	395	274	416
	24 hours	350	105	103	92
	1 year	80	20	21	18
Nitrogen Dioxide - NO2	1 hour	300	239	280	326
	24 hours	150	123	144	170
	1 year	80	46	54	53
Total Suspended Particulate - TSP	1 hour	N/A	-	-	-
	24 hours	260	129	165	258
	1 year	80	61	69	71
Respirable Suspended Particulate - RSP	1 hour	N/A	216	242	349
	24 hours	180	152	155	200
	1 year	55	41	54	50

Notes:

N/A means data is not available.

Concentrations with exceedance of AQOs are bolded

6.4.4 The measurement results show that both short term maximum values (one hour and 24 hours) and long term maximum values (1 year) are all in compliance with the respective AQO both in years 2001 and 2002.

6.4.5 Sulphur dioxide levels in Hong Kong are below the long term AQO because of the enforcement of the Air Pollution Control (Fuel Restriction) regulations for stationary sources and the Air Pollution Control (Vehicle Fuel) Regulation for mobile sources. Decrease of traffic volume of diesel vehicles in Hong Kong has probably contributed to the nitrogen dioxide decreases in the past few years. For TSP and RSP, the pollutants are constantly low. The key contribution factors are likely to be the fully developed land and consequently less intense construction activities at the Central area.

6.4.6 For the purpose of this air quality assessment, the usual practice of adopting the latest annual average results of the nearest air quality monitoring station for the background air pollution levels will be used.

Future Air Quality

6.4.7 It is less likely that air quality of the area will deteriorate further due to the development of the Project.

6.5 Impact Assessment and Mitigation

6.5.1 According to the schedule of works, the deepest intake shafts (site clearance, formation and excavation) will be finished within a period of about less than 12 months. Dust generating activities such as drilling and muck shift will be mainly conducted through Eastern and Western portal during construction period. The remaining works are mainly on adit lining and finishing works on intakes and portals. It has been assumed that the dust emissions during the excavation of intake shafts will be minimal owing to the small works area and excavated spoil will be collected inside the tunnel for the majority of the intake locations (raise boring method) and transported out from either portal for proper disposal. This should not create unacceptable impact on residents nearby. For only six intakes (W8, W5, RR1, THR(2), WO and HR1) formed by reserve circulation drill method, materials will be excavated in slurry mud, therefore, emission to air will be minimal.

Construction Phase

6.5.2 The principal potential source of air quality impact arising from the construction of Project will be fugitive dust. The temporary dust nuisance from construction activities, measurable as TSP (Total Suspended Particulates) and RSP (Respirable Suspended Particulates) will be generated mainly by removal of tunnelling spoil from the tunnel portals and site formation works. The type of tunnelling spoil is expected to be broken granite, volcanic rock and soil.

6.5.3 The nuisance from emission of construction vehicles at intake shafts is likely to be negligible because it is anticipated that the number of these vehicles will be relatively small for the area involved.

6.5.4 No on-site concrete batching plant will be erected. Any concrete to be used will be transported to the work site. When construction tenders/contracts are prepared, these documents will clearly specify that the Contractor shall not erect or operate on-site concrete batching plant.

6.5.5 Bored-tunnels divided into two sections from Tai Hang Road to Aberdeen Tunnel and Aberdeen Tunnel to Pok Fu Lam are proposed to be constructed as the key components of the proposed Project. The estimated volumes of spoil generated within the alignment have been estimated from engineering drawings produced at this stage. An approximate estimate of material volumes is given in Table 6.4.

Table 6.4 Estimated Total Quantity of Spoil Generated during the

Construction of TBM Tunnel, Intake Shafts and Adits

		Length (m)
Construction activities	External diameter (m)	Granite & Volcanic Rock (m³)	Soil (m³)	Granite & Volcanic Rock (m³)	Soil (m³)
TBM Tunnel
Tai Hang Road to Aberdeen Tunnel	7	4,360	-	167,707	0
Aberdeen Tunnel to Pok Fu Lam	8	6,000	-	308,675	0
Intake Shafts + Ventilation pipes	2.3	3,080	359	12,790	1,491
Adits	2.3	7,556	0	313,77	0
			Total	520,549	1,491

Table 6.5 Proposed Excavation Programme (TBM tunnel, Adits and Intake Shafts)

Proposed excavation programme	Duration	Estimate starting date		Expected finished date
TBM procurement & assembly	14 months	May 2007		June 2008
Tunnel excavation and lining	26 months for TBM with diameter 6.25m (Eastern Portal)	June 2008		July 2010
	25.5 months for TBM with internal diameter 7.25m (Western Portal)	June 2008		Aug 2010
		Eastern Portal		Western Portal
		Start	Finish	Start	Finish
TBM removal	2-4 weeks	Sept 10	Sept 10	Aug 09	Sept 10
Drill & Blast (Adits)	8.5 months for longest adit	Sept 08	Apr 11	Sept 08	Apr 11
Shaft excavation by raise boring / reverse circulation drill method	2 months for deepest shaft	Aug 08	Mid May 11	Aug 08	June 11
Adits lining	2 months	Sept 08	Apr 11	Sept 08	Apr 11
Finishing (Eastern & Western Portal & Intake Shafts)	4.5 months	Apr 11	Jul 11	May 11	Sept 11
Landscaping Works & Correction of Defects	3.5 months	End Jul 11	Mid Nov 11	Mid Sept 11	Mid Nov 11
		55 months		55 months

6.5.6 The proposed excavation programme is shown in Table 6.5. Based on this programme, estimated total quantity of spoil generated to be transported out of Eastern and Western portals during construction are approximate 185,073 m³ and 336,967 m³ respectively from Jun 2008 - May 2011. Based on the average truck load capacity of 6m³, it is estimated that the maximum number of loaded trucks will be approximate 10 vehicles per hour (5in/5out) at Eastern Portal. For Western Portal, excavated spoil will be transported by barge. Details of estimation are shown in Tables 6.6a and 6.6b. Given such a small number of truck trips for transportation, dust nuisance is expected to be insignificant if the standard site good housekeeping practice is in place.

Table 6.6a Estimated Spoil Generated Breakdown from Eastern Portal

for 24 hours TBM operation resume

Eastern Portal	Construction Period & Duration	Total volume, m³	m³/month	m³ / day by truck
Bored tunnel (Tai Hang Road to Aberdeen Tunnel) (Granite & Volcanic Rock)	June 2008 to July 2010 (26 months)	167,707	6,450	215
Adits (Granite & Volcanic Rock)	September 2008 to April 2011 (31.5 months)	13,741	436	15
Adits (Soil)		-	-	-
Intake Shafts & Ventilation Pipes (Granite & Volcanic Rock)	August 2008 to May 2011 (33.5 months)	3,165	95	3
Intake Shafts & Ventilation Pipes (Soils)		460	14	0.5
Total		185,073	6,995	233.5

Table 6.6b Estimated Spoil Generated Breakdown from Western Portal

for 24 hours TBM operation resume

Eastern Portal	Construction Period & Duration	Total volume, m³	m³/month	m³ / day by barge
Bored tunnel (Aberdeen Tunnel to Pok Fu Lam) (Granite & Volcanic Rock)	June 2008 to August 2010 (26.5 months)	308,674	11,648	388
Adits (Granite & Volcanic Rock)	September 2008 to April 2011 (31 months)	17,636	569	19
Adits (Soil)		-	-	-
Intake Shafts & Ventilation Pipes (Granite & Volcanic Rock)	August 2008 to June 2011 (34 months)	9,625	283	10
Intake Shafts & Ventilation Pipes (Soils)		1,032	30	1
Total		336,967	12,530	418

6.5.7 For Western portal, spoil generated will be delivery to barges by means of a covered conveyor belt. As a result, the number of vehicles entering the site will be reduced hugely and no vehicle-generated air pollution problems will arise. However, dust may be emitted from the transfer points of the conveyor. Proper design and maintenance of the conveyor will reduce dust emissions from the transfer points to ensure low dust impact.

6.5.8 The remaining construction activities are not expected to produce any dust nuisance to the air sensitive receivers. Landscaping areas within the Project will not involve significant movement of earth materials; hence dust impacts are expected to be insignificant.

Mitigation Measures

6.5.9 In order to comply with the Air Pollution Control Ordinance (APCO), the Contractor should undertake at all times to prevent dust nuisance as a results of his activities. The Contractor will be required to follow all the requirements for dust control stipulated in the Air Pollution Control (Construction Dust) Regulation. Dust suppression measures shall be implemented and shall be incorporated into the Contract Specification, the following fugitive dust suppression measures are to be implemented during the construction phase.

Dust Mitigation Measures

(i) The Contractor shall undertake at all times to prevent dust nuisance as a result of his activities. Effective dust suppression measures should be installed to minimize air quality impacts, at the boundary of the site and at any sensitive receivers.

(ii) No blasting shall be carried out when the strong wind signal or tropical cyclone warning signal No. 3 or higher is hoisted (unless prior permission of the Commissioner of Mines is obtained).

(iii) Effective water sprays shall be used during the delivery and handling of all sand, aggregate and other similar materials, when dust is likely to be created, to dampen all stored materials during dry and windy weather. Watering of exposed surfaces shall be conducted as often as possible depending on the circumstances.

(iv) A watering programme of once every 2 hours in normal weather conditions, and hourly in dry/windy conditions.

(v) Any stockpile of dusty material cannot be immediately transported out of the Site shall be either: a) covered entirely by impervious sheeting; b) placed in an area sheltered on the top and the three sides; or c) sprayed with water or a dust suppression chemical so as to maintain the entire surface wet.

(vi) Should a conveyor system be used, the Contractor shall implement the following precautionary measures. Conveyor belts shall be fitted within windboards. Conveyor transfer points and hopper discharge areas shall be enclosed to minimize dust emission. All conveyors under control of the Contractor, and carrying materials which have the potential to create dust, shall be totally enclosed and fitted with belt cleaners.

(vii) Any dusty materials being discharge to vehicle from a conveying system at fixed transfer point, a three-sided roofed enclosure with a flexible curtain across the entry shall be provided. Exhaust fans shall be provided for this enclosure and vented via a suitable fabric filter system.

(viii) The heights from excavated spoils are dropped should be minimise to reduce the fugitive dust arising from unloading/loading.

(ix) The Contractor shall confine haulage and delivery vehicles to designated roadways inside the site. If in the opinion of the Engineer, any motorised vehicle is causing dust nuisance, the Engineer may require that the vehicle be restricted to a maximum speed of 15 km per hour while within the site area.

(x) Areas within the site where there is a regular movement of vehicles shall have an approved hard surface, be kept clear of loose surface materials and / or be regularly watered.

(xi) Wheel cleaning facilities shall be installed for both portals and used by all vehicles leaving the site. No earth, mud, debris, dust and the like shall be deposited on public roads. Water in the wheel cleaning facility shall be changed at frequent intervals and sediments shall be removed regularly. The Contractor shall submit details of proposals for the wheel cleaning facilities to the Engineer prior to construction of the facility. Such wheel cleaning facilities shall be usable prior to any earthwork excavation activity on site. The Contractor shall provide a hard-surfaced road between any cleaning facility and the public road.

(xii) Chemical wetting agents shall only be used on completed cuts and fills to reduce wind erosion.

(xiii) No vehicle exhausts shall be directed towards the ground or downwards to minimize dust nuisance.

(xiv) Ventilation system, equipped with proprietary filters, should be provided to ensure the safe working environment inside the tunnel. Particular attention should be paid to the location and direction of the ventilation exhausts. The exhausts should not be allowed to face any sensitive receivers directly. Consideration should also be given to the location of windows, doors and direction of prevailing winds in relation to the nearby sensitive receivers.

(xv) In the event of any spoil or debris from construction works being deposited on adjacent land, or stream, or any silt being washed down to any area, then all such spoil, debris or material and silt shall be immediately removed and the affected land and areas restored to their natural state by the Contractor to the satisfaction of the Engineers.

6.5.10 In addition, based on the Air Pollution Control (Construction Dust) Regulation, any works involved regulatory and notifiable works, such as stockpiling, loading and unloading of dusty materials, shall take precautions to suppress dust nuisance. Examples of dust suppression methods are:

· The working area of any excavation or earthmoving operation shall spray with water or a dust suppression chemical immediately before, during and immediately after the operation so as to maintain the entire surface wet;

· Exposed earth shall be properly treated by compaction, turfing, hydroseeding, vegetation planting or sealing with latex, vinyl, bitumen or other suitable surface stabiliser within six months after the last construction activity on the construction site or part of the construction site where the exposed earth lies;

· Any stockpile of dusty materials (greater than 20 m³) shall be either covered entirely by impervious sheeting or placed in an area sheltered on the top and three sides; and sprayed with water or a dust suppression chemical so as to maintain the entire surface wet; and

· Other suitable dust control measures as stipulated in the Air Pollution Control (Construction Dust) Regulation, where appropriate, should be adopted.

6.6 Operation Impact Assessment

6.6.1 None of area will likely be subject to adverse air quality impact due to the operation of the proposed Project.

6.7 Concurrent Projects and Potential Cumulative Impacts

6.7.1 There are no scheduled concurrent public works in the vicinity of the proposed tunnel portals, intakes or tunnel alignment. The northern access road to Cyberport is complete before commencement of construction for this Designated Project. No cumulative construction impact is expected from this Designated Project.

6.8 Monitoring and Audit Requirements

6.8.1 An Environmental Monitoring & Audit (EM&A) program in respect of dust issues will be carried out to monitor compliance with acceptable levels of air quality indicators and to ensure that the proposed mitigation measures are implemented and that they are effective. Otherwise, it is likely that some nearest air sensitive receivers would suffer unacceptable impact.

6.8.2 Suggested monitoring locations are EP/1 (Lai Sing Court) at Eastern portal and WP/2 (Aegean Terrace) at Western portal. These two representative sensitive receivers are very close to the construction works areas and hence, the most likely being impacted if dust suppression measures are not properly implemented.

6.8.3 No monitoring is required during operation phase.

6.9 Conclusion

6.9.1 The construction dust impact assessment has identified Air Sensitive Receivers (ASRs) within the Study Area. It has also identified those works that have potential to generate substantial dust impact to the nearby ASRs.

6.9.2 The transportation of earth material by trucks over site haul roads for both portals is likely to be the dominant dust generation during the excavation of the construction stage. With implementation of the recommended dust suppression measures and backed up by a proper designed EM&A programme, the construction of Project is expected to comply with the AQOs.