4. Air Quality Impact

Introduction

4.1 The potential air quality impacts of the Project are presented in this section. The major sources of air pollution during the construction and operational phases are likely to be dust from construction sites and vehicle exhaust emissions. Air quality impacts on air sensitive receivers (ASRs) have been predicted. Mitigation measures required to protect the ASRs have been recommended, where necessary, to ensure that the air quality criteria would be satisfied.

Environmental Legislation, Standards and Guidelines

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

4.3 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 (HKAQOs) should be satisfied at the Hong Kong Special Administrative Region (HKSAR). The HKAQOs stipulate the maximum allowable concentrations over specific period for a range of pollutants, of which nitrogen dioxide (NO₂), respirable and total suspended particulates (RSP & TSP) are relevant to this Study. Relevant AQOs are listed in Table 4.1.

Table 4.1 Hong Kong Air Quality Objectives

Pollutant	Maximum Concentration (µg m^-3) ⁽¹⁾
	Averaging Time
	1 hour ⁽²⁾	24 hour ⁽³⁾	Annual ⁽⁴⁾
Nitrogen Dioxide (NO₂)	300	150	80
Respirable Suspended Particulates (RSP) ⁽⁵⁾	-	180	55
Total Suspended Particulates (TSP)	-	260	80

(1) Measured at 298 K and 101.325 kPa.

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

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

(4) Arithmetic mean.

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

4.4 The EIAO-TM stipulated that the hourly TSP level should not exceed 500 mgm^-3 (measured at 25°C and one atmospheric) for construction dust impact assessment. Mitigation measures from construction sites have been specified in the Air Pollution Control (Construction Dust) Regulation.

Description of the Environment

4.5 The Assessment Area is a rural area with a few village houses located in Luk Keng Tsuen. The ambient air quality in the Assessment Area is mainly affected by traffic emission from North Lantau Highway. The on-going construction activities in the Sunny Bay area would also incur temporary effect on the air quality of the Assessment Area.

4.6 There is no fixed air quality monitoring station near the Assessment Area. Reference is made to the annual average air pollutant levels recorded during 2000-2003 at the nearest air quality monitoring station which is in Tung Chung. Table 4.2 presents the 4-years annual average concentrations of the pollutants recorded at Tung Chung.

Table 4.2 Air Pollutant Levels Recorded at EPD’s Air Quality Monitoring Station in Tung Chung

Air Pollutant	4-years Annual Average Concentration (mg/m³) Tung Chung ⁽¹⁾
NO₂	45
TSP	69
RSP	49

(1) Air Quality in Hong Kong, 2000-2003, Environmental Protection Department

Air Sensitive Receivers

4.7 Four representative air sensitive receivers (ASRs) were identified for this assessment (Table 4.3) in accordance with the criteria set out in the EIAO-TM. Existing ASRs were confirmed through site visits and review of the survey maps. Planned / Committed ASRs were identified by reference to relevant Outline Zoning Plans, Outline Development Plans, Layout Plans and other published plans in relation to the planning and development within the assessment area, and they include the Theme Park Gateway, Tourist and Convention Village and the proposed Country Park Extension Area. A brief description of the representative ASRs are given in Table 4.3. Figure 4.1 shows the locations of the ASRs.

Table 4.3 Description of Representative ASRs

ASR	Location	Distance from the Project Site Boundary, m	Construction Phase	Operation Phase
A1	Luk Keng Tsuen	220	b	b
*^#A2	Theme Park Gateway	150	r	b
*^#A3	Tourist and Convention Village	460	r	b
*A4	Proposed Country Park Extension Area	410	b	b

Note: * Planned ASRs identified according to Northshore Lantau Development Feasibility Study RODP dated 14/7/2000.

^#The tentative year of commencement for the Theme Park Gateway and Tourist and Convention Village would be 2014 according to CEDD’s latest master development programme for the NLDFS development.

Assessment Methodology

Construction Phase

4.8 Air quality impacts pertinent to the construction of NLDFS developments including the future Road P1 and the Theme Park along with its associated developments were assessed in details in the NLDFS and Theme Park EIA studies. For the purpose of the present study, reference was made to the findings and recommendations of the two aforesaid EIA studies. Additionally, potential sources of air quality impact that may arise during the construction phase of the Project were identified. Taking into consideration the site conditions, nature and scale of the proposed construction works, separation distances between the ASRs and the proposed work sites, effects of implementation of construction dust control measures as stipulated in Air Pollution Control (Construction Dust) Regulation under the APCO and cumulative impacts from concurrent construction activities in the Sunny Bay area, potential air quality impacts were evaluated and their impact significance determined.

Operation Phase

4.9 The USEPA approved air dispersion model, California Line Source Dispersion Model, CALINE 4, was used to predict vehicle exhaust pollutants from open road emissions due to the proposed Project and surrounding road network. All major roads within 500m from the project site boundary were included in the model. The hourly average NO₂, daily average NO₂ and RSP were predicted at 1.5m above ground level at representative ASRs.

4.10 Peak hour traffic flows and vehicle mixes for the road networks in 2023 were used for the assessment of the worst-case air quality scenario. The traffic forecast plan of year 2023 is shown in Appendix 2.2.

4.11 Fleet emission factors for NO_x and RSP, developed based on EURO4 Model, were used for this EIA. As emission factors beyond 2011 are not available, 2011 vehicle emission factors were assumed for traffic beyond 2011, as a worst case scenario. The fleet emission factors for road links were calculated as the weighted average of the emission factors for different types of vehicles.

4.12 Comparison of vehicle emissions for different scenario years was conducted, and is summarised in Table 4.4. North Lantau Highway (NLH) was selected as the subject of comparison for its traffic flow and thence its emission strength would be highest amongst all other roads within the assessment area. It was predicted that peak hour traffic flows in year 2023 would produce the highest amount of pollutants (highest total NO_x emission) and year 2023 traffic data were employed in this EIA as the worst case scenario. Detailed calculations for the total NO_x emissions of NLH for years 2008 and 2023 and the composite emission factors for each road link in year 2023 are given in Appendix 4.1.

Table 4.4 Comparison of Traffic Emission for Different Scenario Year

Year	Road	Peak Traffic Flow (vehicles/hour)	Total NO_x Emission (g/mile-hour)
2008	North Lantau Highway	5320	21572.6
2023	North Lantau Highway	9370	32907.4

4.13 For the calculation of NO₂ concentrations, the vehicular emission factor of NO_x was adopted and the conversion factor from NO_x to NO₂ was assumed to be 20%. With reference to the Screening Procedures for Estimating the Air Quality Impact of Stating Source (EPA-454/R-92-019), a conversion factor of 0.4 was used to convert the 1-hour average concentrations to 24-hour average concentrations.

4.14 As discussed in Sections 2.57 and 2.58, air quality impact due to vehicle emissions arising from an emergency scenario were also assessed. The assessment was based on traffic conditions of a hypothetical emergency scenario. It should be noted that such an emergency would only happen rarely and its duration would be limited, the assessment for the emergency scenario would be adopted as a reference scenario only. Calculations of emission factors for each road link for the normal and emergency scenario in year 2023 are given in Appendix 4.2.

4.15 The following worst case daytime meteorological conditions have been used in the air quality modelling using the CALINE4 model:

§ Wind speed : 1 m/s

§ Wind direction : worst case

§ Wind variability : 18°

§ Stability class : D

§ Surface roughness : 60 cm

§ Mixing height : 500 m

4.16 Background concentrations of NO₂ and RSP were taken as 45 mg/m³ and 49mg/m³respectively, which were added to the corresponding predicted concentrations. Sample computer outputs are provided in Appendix 4.3.

4.17 The above described methodology had previously been applied in similar situations in other EIA studies (e.g. NLDFS EIA and Theme Park EIA), and has generally been accepted for use in assessing air quality impacts and comparison of prediction results with EIAO-TM standards.

4.18 There would be some limitations of methodology such as the accuracy of the predictive base data for future e.g. traffic flow forecasts and weather conditions. Quantitative uncertainties in the assessment of impacts should be considered when drawing conclusions from the assessment. In carrying out the assessment, realistic worst case assumptions including the adoption of peak hourly traffic flows and worst case wind direction were made in order to provide a conservative assessment of air quality impacts.

Environmental Impact Identification, Prediction and Evaluation

Construction Phase

4.19 Potential impacts arising from the construction of the proposed Project would include dust generated from construction activities and gaseous emissions from the construction plants and vehicles. The major construction activities for the Project which would be potential sources of construction dust in the Assessment Area include:

§ Reclamation at Sunny Bay, comprising removal of existing seawall, dredging and filling, construction of seawall, surcharging and removal of surcharge;

§ Road works and bridgeworks, including piling using pre-bored H-pile, erection of girder, deck slab and parapet using pre-cast concrete; and

§ Road surfacing.

4.20 For the proposed reclamation at Sunny Bay, all the dredged marine sediment as well as the surcharge material removal would be transported via marine access. Filling, surcharge mount along with other earthworks, on the other hand, would mainly rely on the use of trucks. Material handling, wind erosion and truck movement on unpaved roads would be the major dust generating activities. Materials handled by barge would contain high moisture content and dust emissions from which would be considered not significant. Construction dust emissions due to wind erosion and truck movement on unpaved roads would also be considered minor in light of the limited scale of the proposed reclamation (about 3ha).

4.21 Major dust generating activities for the proposed road/bridge construction would include material handling and truck movements on unpaved site area. The limited scale of the road/bridge construction would be unlikely to give rise to insurmountable dust impact on the surroundings. Moreover, the use of pre-bored H-pile and pre-cast concrete would reduce the emission of dust from piling and the construction of superstructure.

4.22 The concrete units required for the road/bridge structures would be pre-fabricated outside Hong Kong. Therefore, dust due to construction of concrete units for the proposed Project would not arise. Insurmountable off site air quality impact would also not be expected given the small scale of the Project and that the quantity of pre-cast concrete units necessary for the construction would not be substantial.

4.23 Amongst all other work sites proposed for the Project, the reclamation sites under this Project would be located closest to the representative ASRs. The distance from the proposed work sites for reclamation at Sunny Bay to the nearest existing ASRs identified for the present assessment, i.e. Luk Keng Tsuen, would be about 230m. As regards road works and bridge works, work sites would be located further away from ASRs than the proposed reclamation. It would be envisaged that the dust dispersion over the large separation between the potential emission sources and receivers would limit the potential of the proposed works of incurring insurmountable construction dust impact on the ASRs. Table 4.5 presents the distances between various work sites and the representative ASRs.

Table 4.5 Separation Distances Between the Proposed Work Site Boundaries and Representative ASRs

ASR	Location	Approximate Distance from the Nearest Work Site Boundary, m
		Reclamation	Roadwork	Bridgework
A1	Luk Keng Tsuen	220	290	350
A4	Proposed Country Park Extension Area	510	520	550

4.24 It is noteworthy that Contractors are required to ensure that all the proposed works be carried out in accordance with the APCO. In particular, all statutory dust control requirements as stipulated in the Air Pollution Control (Construction Dust) Regulation under the Ordinance must be observed. The implementation of the statutory dust suppression measures such as watering, can be effective in controlling dust arising from various construction activities. In addition, EM&A will be conducted for the Project to ensure that the ASRs would be protected. In connection with this, it would therefore be expected that the construction dust impact can be reduced during the construction stage of the Project.

Cumulative Impacts

4.25 According to the NLDFS EIA, construction activities for the proposed NLDFS developments, which would last from Q2 2000 to 2031 according to the NLDFS, would be carried out in parallel with the proposed Project (Section 2 of this EIA study refers). Construction activities identified within the Assessment Area would be Stage 1 Construction for the proposed NLDFS developments (hereinafter referred to as the “Stage 1 Construction”) which would last from 2000 to 2008. According to the NLDFS EIA, developments under Stage 1 Construction with their work sites falling within the Assessment Area of this Study would include:

§ Construction of transport infrastructure including the CWKLR section between Sunny Bay Interchange to the Route 10 toll plaza, distributor Sunny Bay Road from Sunny Bay to Penny’s Bay, and the Theme Park Resort Roads (D1 and D2); and

§ Construction of PBRL.

4.26 Based on the available information at the time of the submission of this Report, the above two project items would be due for completion by mid 2005. It is envisaged that they would not coincide with the construction of the proposed Project which is scheduled to commence in June 2006. Cumulative dust impacts would not be expected at the ASRs.

4.27 It would be envisaged that the proposed project would not trigger exceedance of the TSP levels as set out in the HKAQO on the following grounds:

§ Limited scale of the proposed works;

§ Materials handled generally with high moisture content;

§ Large separation between the proposed emission sources and receivers;

§ Dust reduction as a result of the implementation of dust control measures in accordance with the Air Pollution Control (Construction Dust) Regulation; and

§ Absence of other concurrent construction activities in the Sunny Bay area giving rise to cumulative dust impacts.

Operation Phase

4.28 Vehicular exhaust emission from open road sections would be the major pollutant sources during the operation phase of the Project. Cumulative air quality impacts of air pollutant sources were identified within the Assessment Area, as listed below:

§ North Lantau Highway (NLH);

§ Link Roads 1-4;

§ Sunny Bay Road; and

§ Road P1 Roundabout, Slip Roads 5-6 and Road A to be constructed under this Project.

4.29 There were no other major vehicle emission sources identified within the assessment area.

4.30 In addition to the prevailing normal traffic conditions, air quality impact assessment for a hypothetical emergency scenario (Sections 2.57-2.58, and 4.14 refer) were conducted. Taking into account vehicle emissions from the above road sections, cumulative 1-hour and 24-hour NO₂ and 24-hour RSP concentrations were predicted at the worst affected level, 1.5m above ground. Table 4.6 presents the modelling results.

Table 4.6 Predicted NO₂ and RSP Concentration at Representative ASRs

ASR	*NO₂ Concentration (mg/m³)		*RSP Concentration (mg/m³)
ASR	1-hour average	24-hour average	24-hour average
*Normal Scenario*
A1	76	57	53
A2	93	64	56
A3	102	68	57
A4	75	57	53
*Emergency Scenario*
A1	88	62	55
A2	125	77	60
A3	111	71	58
A4	80	59	54
AQO Criteria	300	150	180

* Background NO₂ and RSP concentrations of 45mg/m³ and 49mg/m³ were included.

4.31 The 1-hour NO₂ levels, 24-hour NO₂ and 24-hour RSP concentrations were predicted in the range of 75 – 102, 57 – 68 and 53 - 57 mg/m³ respectively for the normal scenario. As for the emergency scenario, modelling results showed that the predicted 1-hour NO₂ level would range from 80-125 mg/m³ while 24-hour NO₂ and RSP would range from 59 to 77 mg/m³and 54 to 60 mg/m³ respectively.

4.32 For both scenarios, all the air pollutant levels were predicted to be within the respective AQO criteria. Adverse air quality impact arising from the implementation of the Project would not be expected. The predicted 1-hour average NO₂, 24-hour average NO₂ and 24-hour average RSP concentrations contour plots at 1.5m above ground for the normal scenario are presented Figures 4.2, 4.3 & 4.4 respectively.

Mitigation of Adverse Environmental Impacts

Construction Phase

4.33 Dust suppression measures stipulated in the Air Pollution Control (Construction Dust) Regulation should be implemented to control dust emission from the site. Major control measures relevant to this Project are listed below, and they are recommended to be included in relevant contract documents:

§ skip hoist for material transport should be totally enclosed by impervious sheeting;

§ all dusty materials should be sprayed with water prior to any loading, unloading or transfer operation so as to maintain the dusty materials wet;

§ stockpiles of aggregate or spoil should be covered and water applied;

§ the height from which excavated materials are dropped should be controlled to a minimum practical height to limit fugitive dust generation from unloading;

§ every vehicle should be washed to remove any dusty materials from its body and wheels before leaving the construction sites; and

§ the load of dusty materials carried by vehicle leaving a construction site should be covered entirely by clean impervious sheeting to ensure dust materials do not leak from the vehicle.

4.34 In addition, good site practices and a comprehensive dust monitoring and audit programme are recommended to minimise cumulative dust impacts.

Operation Phase

4.35 The pollutant levels predicted at all ASRs would be within their respective criteria as set out in the HKAQOs. No mitigation measure would be required during the operation phase.

Evaluation of Residual Impacts

Construction Phase

4.36 With the implementation of the proposed dust suppression measures, good site practice and a comprehensive dust monitoring and audit programme, no adverse residual impact would be envisaged.

Environmental Monitoring and Audit

Construction Phase

4.37 With the proposed dust suppression measures (Section 4.34) and good site practices in place, the dust levels at all ASRs would comply with the dust criteria. Details of the monitoring requirements such as monitoring locations, frequency of baseline and impact monitoring are presented in the Project EM&A Manual.

Operation Phase

4.38 No EM&A is required during the operation phase of the proposed Project.

Conclusion

Construction Phase

4.39 Potential air quality impacts arising from the construction of the proposed Project would include dust from construction activities and gaseous emissions from the construction plants and vehicles. Material handling, wind erosion and truck movement on unpaved roads would be the major dust generating activities.

4.40 Having taken into consideration the prevailing humid site conditions, limited scale of the proposed works, materials handled generally of high moisture content, large separation between the dust emission sources and receivers, dust reduction as a result of the implementation of construction dust control measures as stipulated in the Air Pollution Control (Construction Dust) Regulation under the APCO, and in the absence of concurrent construction activities in the Sunny Bay area, it would be envisaged that proposed Project would not result in exceedance of the TSP levels as set out in the HKAQO.

4.41 Dust suppression measures stipulated in the Air Pollution Control (Construction Dust) Regulation should be implemented to control dust emission from the site. In addition, good site practices and a comprehensive dust monitoring and audit programme were recommended to minimise cumulative dust impacts.

Operation Phase

4.42 Vehicular exhaust emissions from open road sections would be the major air pollutant sources during the operation phase of the Project. Cumulative air quality impacts were assessed by using CALINE 4 model. No exceedance of the AQOs was predicted at all representative ASRs during the operation phase for both the Normal and Emergency Scenarios. Therefore, no mitigation measure is required.