Table of Contents

3.               AIR QUALITY IMPACT.. 3-1

3.1            Introduction. 3-1

3.2            Environmental Legislation, Standards and Criteria. 3-1

Air Quality Objectives & EIAO-TM... 3-1

Air Pollution Control (Construction Dust) Regulation. 3-2

3.3            Existing Environmental Context 3-2

3.4            Existing Background Air Quality Review.. 3-3

3.5            Construction Phase Assessment 3-4

Evaluation of Construction Phase Air Quality Impact 3-4

Construction Phase Mitigation Measures. 3-5

3.6            Operational Phase Assessment 3-7

Identification of Air Sensitive Receivers. 3-7

Identification of Pollution Sources and Key Pollutants. 3-10

Determination of Worst Assessment Year in Air Quality Impact Assessment 3-12

Projected Background Air Quality Result of Year 2021 by PATH Model 3-15

Assessment Methodology. 3-15

Cumulative Impact for “Without Project” Scenario in Year 2021. 3-18

Cumulative Impact for “With Project” Scenario in Year 2021. 3-24

Comparison of Annual Average NO2 Concentrations between “With Project” and “Without Project” Scenarios in Year 2021. 3-29

Mitigation Measures and Residual Impacts. 3-31

3.7            Environmental Monitoring and Audit Requirements. 3-32

Construction Phase. 3-32

Operation Phase. 3-32

3.8            Conclusions. 3-32

Construction Phase. 3-32

Operation Phase. 3-32

Overall 3-32

 


 

LIST OF TABLES

 

Table 3‑1         Hong Kong Air Quality Objectives. 3-1

Table 3‑2         5-year Background Air Quality Data from Kwai Chung Air Quality Monitoring Station. 3-3

Table 3‑3         Representative Air Sensitive Receivers. 3-8

Table 3‑4         Comparison of Road Traffic Flows and Traffic Speeds between “With Project” and “Without Project” Scenarios. 3-12

Table 3‑5         Total Emission Inventory for “Without” Project Scenario. 3-13

Table 3‑6         Total Emission Inventory for “With” Project Scenario. 3-13

Table 3‑7         Predicted Total Traffic Volume in Assessment Years. 3-14

Table 3‑8         Summary of Predicted Results from PATH Model in Year 2021. 3-15

Table 3‑9         Predicted Cumulative Air Pollutants Concentrations under “Without Project” Scenario at 1.5m above Ground in Year 2021. 3-18

Table 3‑10       Predicted Cumulative Air Pollutants Concentrations under “Without Project” Scenario at 5m above Ground in Year 2021. 3-20

Table 3‑11       Predicted Cumulative Air Pollutants Concentrations under “Without Project” Scenario at 10m above Ground in Year 2021. 3-21

Table 3‑12       Breakdown of Total NO2 Annual Average Concentration under “Without Project” Scenario in Year 2021. 3-23

Table 3‑13       Numbers of Predicted Annual Average NO2 Concentration in Compliance of AQOs under “Without Project” Scenario in Different Grids. 3-24

Table 3‑14       Predicted Cumulative Air Pollutants Concentrations under “With Project” Scenario at 1.5m above Ground in Year 2021. 3-25

Table 3‑15       Predicted Cumulative Air Pollutants Concentrations under “With Project” Scenario at 5m above Ground in Year 2021. 3-26

Table 3‑16       Predicted Cumulative Air Pollutants Concentrations under “With Project” Scenario at 10m above Ground in Year 2021. 3-27

Table 3‑17       Breakdown of Total NO2 Annual Average Concentration under “With Project” Scenario in Year 2021. 3-29

Table 3‑18       Difference of Annual Average NO2 between “Without Project” and “With Project” Scenarios in Year 2021. 3-30

 

 

 

LIST OF FIGURES

 

Figure 3.1                    Locations of Air Sensitive Receivers (ASRs)

Figure 3.2                    Road Links of Vehicular Emission Model

Figure 3.3                    Major Roads with Predicted Traffic Flow Changes Due to the Project

Figure 3.4                    Locations of Chimneys within the 500m Study Area

Figure 3.5                    Grids of PATH Model Data within the 500m Study Area

Figure 3.6                    Open Roads at Ground Level

Figure 3.7                    Open Roads on Lai King Hill

Figure 3.8                    Contour of Cumulative Maximum Hourly Average NO2 at 10m above ground (Without Project Scenario in year 2021)

Figure 3.9                    Contour of Cumulative 19th Highest Hourly Average NO2 at 10m above ground (Without Project Scenario in year 2021)

Figure 3.10                  Contour of Cumulative Annual Average NO2 at 10m above ground (Without Project Scenario in year 2021)

Figure 3.11                  Contour of Cumulative Maximum Daily Average RSP at 10m above ground (Without Project Scenario in year 2021)

Figure 3.12                  Contour of Cumulative 10th Highest Daily Average RSP at 10m above ground (Without Project Scenario in year 2021)

Figure 3.13                  Contour of Cumulative Annual Average RSP at 10m above ground (Without Project Scenario in year 2021)

Figure 3.14                  Contour of Cumulative Maximum Daily Average FSP at 10m above ground (Without Project Scenario in year 2021)

Figure 3.15                  Contour of Cumulative 10th Highest Daily Average FSP at 10m above ground (Without Project Scenario in year 2021)

Figure 3.16                  Contour of Cumulative Annual Average FSP at 10m above ground (Without Project Scenario in year 2021)

Figure 3.17                  Contour of Cumulative 19th Highest Hourly Average NO2 at 10m above ground (Without Project Scenario in year 2029)

Figure 3.18                  Contour of Cumulative Annual Average NO2 at 10m above ground (Without Project Scenario in year 2029)

Figure 3.19                  Contour of Cumulative 19th Highest Hourly Average NO2 at 10m above ground (Without Project Scenario in year 2036)

Figure 3.20                  Contour of Cumulative Annual Average NO2 at 10m above ground (Without Project Scenario in year 2036)

Figure 3.21                  Contour of Cumulative Maximum Hourly Average NO2 at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.22                  Contour of Cumulative 19th Highest Hourly Average NO2 at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.23                  Contour of Cumulative Annual Average NO2 at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.24                  Contour of Cumulative Maximum Daily Average RSP at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.25                  Contour of Cumulative 10th Highest Daily Average RSP at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.26                  Contour of Cumulative Annual Average RSP at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.27                  Contour of Cumulative Maximum Daily Average FSP at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.28                  Contour of Cumulative 10th Highest Daily Average FSP at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.29                  Contour of Cumulative Annual Average FSP at 1.5m above ground (With Project Scenario in year 2021)

Figure 3.30                  Contour of Cumulative Maximum Hourly Average NO2 at 10m above ground (With Project Scenario in year 2021)

Figure 3.31                  Contour of Cumulative 19th Highest Hourly Average NO2 at 10m above ground (With Project Scenario in year 2021)

Figure 3.32                  Contour of Cumulative Annual Average NO2 at 10m above ground (With Project Scenario in year 2021)

Figure 3.33                  Contour of Cumulative Maximum Daily Average RSP at 10m above ground (With Project Scenario in year 2021)

Figure 3.34                  Contour of Cumulative 10th Highest Daily Average RSP at 10m above ground (With Project Scenario in year 2021)

Figure 3.35                  Contour of Cumulative Annual Average RSP at 10m above ground (With Project Scenario in year 2021)

Figure 3.36                  Contour of Cumulative Maximum Daily Average FSP at 10m above ground (With Project Scenario in year 2021)

Figure 3.37                  Contour of Cumulative 10th Highest Daily Average FSP at 10m above ground (With Project Scenario in year 2021)

Figure 3.38                  Contour of Cumulative Annual Average FSP at 10m above ground (With Project Scenario in year 2021)

 

 

 

APPENDICES

 

Appendix 3-1      Construction Area of Heavy Construction Activities

Appendix 3-2      Road Links and Traffic Breakdown of 16 Vehicle Types

Appendix 3-3      Chimney Survey and Emission Inventory

Appendix 3-4      Summary of 2020 Hong Kong Emission Inventory for the PATH Model

Appendix 3-5      Assumptions on the Adjusted PATH Model for Year 2021

Appendix 3-6      Estimation of Emission Factor

Appendix 3-7      Hourly Emission Factors in Grams per Miles per Vehicles

Appendix 3-8      Cumulative Results for Separated Grids at Different Levels for “Without Project” Scenario in Year 2021

Appendix 3-9      Detailed Breakdown from Background, Road and Chimney Emissions for "Without Project" Scenario in Year 2021

Appendix 3-10    Comparison of Cumulative Impact Result of NO2 Annual Average of Different Levels in “Without Project” in the Year of 2021, 2029 and 2036

Appendix 3-11    Cumulative Results for Separated Grids at Different Levels for “With Project” Scenario in Year 2021

Appendix 3-12    Detailed Breakdown from Background, Road and Chimney Emissions for "With Project" Scenario in Year 2021

Appendix 3-13    Comparison of Cumulative Impact Result of NO2 Annual Average between “Without Project” and “With Project” Scenarios at 1.5m, 5m and 10m in Year 2021

 

 

 

 

3.                       AIR QUALITY IMPACT

3.1                   Introduction

3.1.1             This section identifies potential air quality impacts that may arise from the construction and operation of the Project. Fugitive dust impact during the construction phase and the potential air quality impact arising from the operation phase of the Project have been assessed. Where necessary, appropriate mitigation measures will be recommended to reduce the impacts contributed by the Project to the identified Air Sensitive Receivers (ASRs) so as to satisfy the corresponding environmental legislations and guidelines.

3.2                   Environmental Legislation, Standards and Criteria

3.2.1             The relevant criteria and standards as specified in the following legislation and guidelines shall be followed in evaluating the air quality impact assessment in this study:

·         Environmental Impact Assessment Ordinance (EIAO) (Cap.499.S16), EIAO-TM, Annexes 4 and 12;

·         Air Pollution Control Ordinance (APCO) (Cap. 311);

·         Air Pollution Control (Construction Dust) Regulation;

·         Requirement set out under Clause 3.4.4 of the EIA Study Brief (No. ESB-242/2012).

 

Air Quality Objectives & EIAO-TM

3.2.2             The Air Pollution Control Ordinance (APCO) (Cap 311) provides a regulatory framework for controlling air pollutants from a variety of stationary and mobile sources and it encompasses an Air Quality Objectives (AQOs), effective in 2014.

3.2.3             The AQOs stipulate the concentrations for a range of pollutants, namely sulphur dioxide (SO2), respirable suspended particulates (RSP), fine suspended particulates (FSP), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and lead (Pb). The AQOs are summarised in Table 3‑1.

Table 31      Hong Kong Air Quality Objectives

Pollutant

Concentration Limit (mg/m3) Averaging Time(i)(v)

10-min

1 Hour

8 Hours

24 Hours

1 Year (iv)

Sulphur Dioxide

500 (3)

-

-

125 (3)

-

Respirable Suspended

Particulates (ii)

-

-

-

100 (9)

50

Fine Suspended Particulates (iii)

-

-

-

75 (9)

35

Nitrogen Dioxide

-

200 (18)

-

-

40

Ozone

-

-

160 (9)

-

 

Carbon Monoxide

-

30,000

10,000

-

 

Lead

-

-

-

-

0.5

Notes: (i)             All measurements of the concentration of gaseous air pollutants, i.e., sulphur dioxide, nitrogen dioxide, ozone and carbon monoxide, are to be adjusted to a reference temperature of 293 Degrees Kelvin and a reference pressure of 101.325 kilopascal.

(ii)           Respirable suspended particulates mean suspended particles in air with a nominal aerodynamic diameter of 10 µm or less.

(iii)          Fine suspended particulates means suspended particles in air with a nominal aerodynamic diameter of 2.5 µm or less.

(iv)          Arithmetic means.

(v)           The numbers in brackets ( ) refer to number of exceedances allowed per year.

 

3.2.4             The Annex 4 of EIAO-TM stipulates that hourly Total Suspended Particulate (TSP) level should not exceed 500µg/m3 measured at 298K and 101.325kPa (one atmosphere) for the construction dust impact assessment. Mitigation measures for construction sites are specified in the Air Pollution Control (Construction Dust) Regulation. Notifiable and regulatory works are, also, under the control of the Air Pollution Control (Construction Dust) Regulation.

3.2.5             Guidelines for conducting air quality assessment are stipulated in Annex 12 of EIAO-TM, including the determination of ASRs, the assessment methodology, baseline study and impact prediction and assessment.

Air Pollution Control (Construction Dust) Regulation

3.2.6             Under the Air Pollution Control (Construction Dust) Regulation, the contractors should inform Environmental Protection Department (EPD) for any notifiable and regulatory works. Notifiable works are site formation, reclamation, demolition, foundation works 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 materials handling, excavation, concrete works, etc. As both notifiable works and regulatory works are included in this Project, contractors and site agents should inform the EPD for carrying out construction works and should adopt dust control measures to reduce dust emissions to the acceptable level.

3.3                   Existing Environmental Context

3.3.1             The Project is located in the existing urban area of Kwai Chung.  The land uses within the study area consists predominately of urban residential, institutional, industrial and commercial areas according to Kwai Chung Outline Zoning Plan (OZP) No. S/KC/28.  Residential areas with a number of public housing estates, private premises and schools at Lai King Hill are mainly located to the east of the proposed flyover, while major industrial areas are located to the northwest of the Project.

3.3.2             In close vicinity to the west of the proposed flyover is Kwai Chung Container Terminal (KCCT), which consists of nine container terminals with 24 berths. The container terminals occupy 279 hectares of coastal areas along Rambler Channel and on Stonecutters Island, as well as 7,694 meters of deep water frontage. Total handling capacity of the container terminals is about 20 million TEUs[1] per year. It is the main port facility in Hong Kong and is the third busiest container port in the world. It has been anticipated that emission associated with the marine vessels and the operation of KCCT is one of the major sources of air pollution in the existing Kwai Tsing District. Given the arrival number of marine vessels reaching KCCT would keep growing in the coming years, air pollution due to marine vessels and KCCT would still be dominant.

3.3.3             Apart from the emissions from the marine vessels and KCCT, vehicular emissions from open road section of the Project and nearby heavily trafficked road network (e.g. Tsuen Wan Road, Kwai Chung Road, Tsing Kwai Highway and Kwai Tsing Road) as well as industrial emissions at the northern west to the Project would also contribute to air pollution issue within the study area. Details of air pollution emission sources identified within the 500 metres study area in this Project are discussed in Section 3.6.

3.3.4             The new flyover is proposed to be constructed in order to resolve the forecasted traffic congestion on the south bound carriageway of Tsuen Wan Road (TWR) between Kwai Tsing Interchange (KT I/C) and Kwai Chung Road (KCR) during peak hours in the future. Due to the implementation of this Project, more free traffic flow and improvement in the overall vehicular emission from those road sections are anticipated.


3.4                   Existing Background Air Quality Review

3.4.1             The nearest EPD Air Quality Monitoring Station to the study area is Kwai Chung Air Quality Monitoring Station (KCAQMS). The background air quality levels applicable to this Project could make reference to the latest 5-year data (2009 to 2013) recorded at KCAQMS, as summarised in Table 3‑2.

Table 32     5-year Background Air Quality Data from Kwai Chung Air Quality Monitoring Station

Pollutant

Year

Maximum Concentration (mg/m3) Averaging Time

1-Hour

24-Hour

8-Hour

Annual

NO2

 

 

 

 

 

 

2009

260 [40]

200.3

N/A

64.4

2010

280 [34]

159.1

N/A

64.9

2011

290 [28]

164.7

N/A

66.9

2012

292 [32]

147

N/A

63.8

2013

306 [42]

161

N/A

68.9

5-year mean

285.6

166.4

N/A

65.8

AQOs

200 (18)

N/A

N/A

40

RSP

 

 

 

 

 

 

2009

210

180.4 [6]

N/A

46.6

2010

628(6)

505.2 [7](6)

N/A

45

2011

204

119.8 [9]

N/A

48.3

2012

179

145.3 [4]

N/A

42.1

2013

231

150.6 [20]

N/A

46.3

5-year mean

290.4

220.3

N/A

45.7

AQOs

N/A

100 (9)

N/A

50

FSP (3)

 

 

 

 

 

 

2009

- (2)

- (2)

N/A

- (2)

2010

- (2)

- (2)

N/A

- (2)

2011

164

98.6 [12]

N/A

35.5

2012

143

82.7 [4]

N/A

29.2

2013

197

126.6 [24]

N/A

32.2

3-year mean (3)

168

102.6

N/A

32.3

AQOs

N/A

75 (9)

N/A

35

SO2

 

 

 

 

 

 

2009

269

112.3 [0]

N/A

21.4

2010

211

94.2 [0]

N/A

21.4

2011

228

85 [0]

N/A

21.1

2012

232

88.3 [0]

N/A

16.5

2013

254

104.6 [0]

N/A

20.2

5-year mean

238.8

96.9

N/A

20.1

AQOs

N/A

125 (3)

N/A

N/A

O3

 

 

 

 

 

 

2009

N/A

N/A

146.6

32.6

2010

N/A

N/A

166.0

28.4

2011

N/A

N/A

135.8

28.3

2012

N/A

N/A

174.6

30.3

2013

N/A

N/A

140.6

30.0

5-year mean

N/A

N/A

152.7

29.9

AQOs

N/A

N/A

160

N/A

TSP

 

 

 

 

 

2009

N/A

144

N/A

70

2010

N/A

234

N/A

71

2011

N/A

149

N/A

71

2012

N/A

166

N/A

66

2013

N/A

168

N/A

66

5-year mean

N/A

172.2

N/A

68.8

Annex 4 of EIAO-TM

500

N/A

N/A

N/A

              Notes:

(1)            Values bolded and underlined had exceeded the prevailing AQOs value.

(2)            “-” indicated no data is available for the corresponding periods.

(3)            No data of FSP were available from 2009 to 2010 at Kwai Chung EPD Air Quality Monitoring Station, 3 year average from 2011 to 2013 are adopted.

(4)            Number in ( ) indicate the number of exceedance allowed to comply with the AQOs.

(5)            Number in [ ] indicate the number of exceedance recorded.

(6)            The maximum 1-hour and 24-hour average RSP concentrations recorded in Year 2010 was due to a dust storm originated from Northern China.

 

3.4.2             The table above indicates that the maximum daily SO2, annual and the maximum 8-hour O3, annual RSP and annual FSP recorded at KCAQMS are well within the AQOs in the past five years. However, maximum hourly NO2, annual NO2, daily maximum RSP and daily FSP exceed the AQOs from year 2009 to 2013.

3.4.3             Concentrations of the maximum hourly NO2 for the past 5 years ranged from 260µg/m3 to 306µg/m3 with exceedance frequency of AQOs by at least 28 times, which is far more than the allowance stipulated in the AQOs of less than 18 times per year. For annual NO2, an average value of 65.8µg/m3 is calculated over the past 5 years. This value is much higher than the AQO of 40µg/m3.

3.4.4             Exceedances of AQOs could be found also in both the maximum daily RSP and FSP from 2009 to 2013. The record of FSP at Kwai Chung monitoring station was not available until 2011. The maximum daily FSP has an average value of 102.6µg/m3 ranging from 82.7µg/m3 to 126.6µg/m3 all of which were above the AQO of 75µg/m3. The number of exceedance in 2011 and 2013 is beyond the limit of 9 times under the AQO.

3.4.5             The data recorded at KCAQMS indicated that before the commencement of the proposed project, maximum hourly and annual average NO2, maximum daily average RSP and FSP have already exceeded the AQOs as prevailing air quality conditions.

3.5                   Construction Phase Assessment

3.5.1             This section presents the assessment of potential air quality impacts associated with the construction phase of the Project. The assessment has been conducted in accordance with the requirements given in Clause 3.4.4 and Section 3 of Appendix B of the EIA Study Brief (No. ESB-242/2012).

3.5.2             According to the Clause 3.4.4 of the EIA Study Brief, a quantitative assessment is required only if the project will give rise to significant construction dust impacts at the ASRs likely to exceed the recommended limits in the TM, despite the incorporation of the dust control measures proposed. In this project, based on the assessment of the construction phase air quality impact and the recommendation of construction phase mitigation measures in the following sections, it is expected that no significant construction dust impact would be generated during the construction stage and no exceedance of relevant AQOs is expected. Therefore, the construction dust impacts are assessed qualitatively.

Evaluation of Construction Phase Air Quality Impact

3.5.3             Fugitive dust will be potentially generated by heavy construction activities during the construction phase, including excavation works, earth movement, stockpiling, loading and unloading, etc. The major dust-emitting construction activities of the Project have been identified and listed as follows:

·                Construction of an additional traffic lane (Bridge H);

·                Modification of existing slip roads (Bridge G);

·                Demolition of the existing footbridge NF303;

·                Construction of footbridge and associated footpath reprovision;

·                Relocation and modification of existing bus lay-by; and

·                Modification of Kwai Chung Road.

 

3.5.4             The preliminary programme of heavy construction activities and the corresponding locations of dust emission work are shown in Appendix 3-1. The tentative schedule of construction will commence in the first quarter of 2018 and complete by the third quarter of 2021.

3.5.5             Dust-emitting activities would be carried out at different construction periods according to the construction programme with minimum overlapping. In general, the active heavy construction areas typically range from 100m2/month to 1300m2/month. Among the maximum construction area of 1300m2/month, 1200m2/month are mainly from road works of Bridge H, while the remaining 100m2/month are the stockpiling area. In fact, the active heavy construction areas from road works of Bridge H will only occupy approximately 300m2 per week. The extents of the active construction works are generally small, comparing to the usual construction sites. Also, there would be limited quantity of equipment being adopted on-site, including breaker, excavator, and concrete mixer. Parallel construction activity and overlapping of different work stages should be avoided as far as practicable. Hence, the concurrent open area involved for each procedure of work would be constrained by the number of equipment adopted. In addition, majority components of the proposed flyover are pre-casted for on-site installation. Part of the construction and demolition (C&D) materials generated would be reused and backfilled on-site. Therefore, concrete batching and transporting dusty materials is minimised.

3.5.6             In this connection, the number of parallel heavy construction activities would be avoided as far as practicable, and the adverse air quality impact to the surrounding sensitive receivers would be minimised. As a result, it is anticipated that there is no adverse impact from fugitive dust emitted from the heavy construction activities.

3.5.7             In view of the relatively small project scale, the abundant margin of the relevant standards, and the topographic nature of the nearest ASRs which locate at a relative higher elevations over the construction works area, significant dust generation from the construction of the Project is not anticipated, especially after the implementation of good site practices and sufficient dust suppression measures stipulated under the Air Pollution Control (Construction Dust) Regulation. Therefore, adverse impact is not anticipated at the ASRs and quantitative dust impact assessment is considered not necessary.

Construction Phase Mitigation Measures

3.5.8             As no massive earthworks and excavation works are required during the construction of the Project, adverse air quality impact arising from the fugitive dust is not anticipated.  Dust suppression measures as stipulated under the Air Pollution Control (Construction Dust) Regulation, and good site practices should be implemented to further minimise the construction dust generated. The following dust suppression measures should be incorporated by the Contractor to control the dust nuisance throughout the construction phase.

·                Every temporary access road shall be paved with concrete, bituminous materials, hardcores or metal plates, and kept clear of dusty materials; or sprayed with water or a dust suppression chemical so as to maintain the entire road surface wet.

·                Any stockpile of dusty materials shall be covered entirely by impervious sheeting, placed in an area sheltered on the top and the 3 sides, or sprayed with water or a dust suppression chemical so as to maintain the entire surface wet. The materials should be removed or backfilled or reinstated where practicable within 24 hours of the excavation or unloading.

·                All dusty materials shall be sprayed with water or a dust suppression chemical immediately prior to any loading, unloading or transfer operation so as to maintain the dusty materials wet.

·                Vehicles used for transporting dusty materials should be covered with tarpaulin or similar material, and the cover should extend over the edges of the sides and tailboards.

·                Vehicle wheel washing facilities should be provided at each construction site exit. Immediately before leaving a construction site, every vehicle shall be washed to remove any dusty materials from its body and wheels.

·                Where a vehicle leaving a construction site is carrying a load of dusty materials, the load shall be covered entirely by clean impervious sheeting to ensure that the dusty materials do not leak from the vehicle.

·                The speed of vehicles on unpaved road within the site should be controlled to not higher than 10 km/hr.

·                Routing of vehicles and positioning of construction plants should be arranged at maximum possible distances from the sensitive receivers.

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

·                Loading, unloading, transfer, handling or storage of large amount of cement or dry PFA should be carried out in a totally enclosed system or facility, and any vent or exhaust should  be fitted with the an effective fabric filter or equivalent air pollution control system.

·                Exposed earth shall be properly treated by compaction, turfing, hydroseeding, vegetation planting or sealing with latex, vinyl, bitumen, shotcrete or other suitable surface stabilizer within 6 months after the last construction activity on the construction site or part of the construction site where the exposed earth lies.

 

3.5.9             The abovementioned requirements are recommended to be incorporated into the contract specification for the civil work. In addition, a monitoring and audit programme during the construction phase should be implemented by the Contractors to ensure that the construction dust impacts are well managed and recorded, and thus to be controlled within the acceptable criteria.

3.5.10         In accordance with Section I Clause 3 (ii) in Appendix B of the EIA Study Brief (No. ESB-242/2012), a monitoring and audit programme for the construction phase of the Project shall be devised to verify the effectiveness of the control measures proposed so as to ensure proper construction dust control. Detailed requirements for the monitoring and audit programme are presented separately on the EM&A Manual.


3.6                   Operational Phase Assessment

3.6.1             Potential air quality impacts arising from the operation phase of the Project will be described in this section. Background air quality estimation, identification of air pollution sources and representative ASRs, and the methodology adopted for the assessment will be presented. The assessment is conducted in accordance with Clause 3.4.3 and Appendix B of the EIA Study Brief (No. ESB-242/2012).

3.6.2             The flyover is planned to be in operation in year 2021.  With the consideration of air quality improvement schemes implemented by the government, such as “A Clean Air Plan for Hong Kong” which aims to tackle roadside air pollution and to reduce marine emissions, the first year of operation (year 2021) is anticipated to be the worst assessment year for the Project, in terms of potential air quality impact.

Identification of Air Sensitive Receivers

3.6.3             With reference to Section 3.4.4 of EIA Study Brief (No. ESB-242/2012), study area for air quality impact assessment should be defined by a distance of 500 metres away from the project boundary. ASRs are identified in accordance with Annex 12 of EIAO-TM, including any domestic premises, hotels, hostels, hospitals, medical, clinics, nurseries, temporary housing accommodation, schools, educational institutions, offices, factories, shops, shopping centres, places of worship, libraries, courts of law, sports stadiums or performing arts centres. The graph below illustrates the general distribution of ASRs identified within the 500m study area.

Legend:

      Assessed ASRs

      500m Study Area

      Project Boundary

 

 

Locations of Representative ASRs within 500m Study Area of this Project

3.6.4             The existing ASRs have been identified with reference to the latest information showing on the survey maps, topographic maps, aerial photos and land status plans. Various site surveys have been undertaken to verify and confirm with the above desktop studies.

3.6.5             The planned ASRs have been identified with reference to the latest information including those earmarked on the Kwai Chung Outline Zoning Plan (OZP S/KC/28) and other relevant published land use plans, including plans and drawings published by Lands Department and any land use and development applications approved by the Town Planning Board.

3.6.6             Details of the identified representative ASRs are shown in Figure 3.1 and summarised in Table 3‑3 below. ASRs identified in this assessment have different degree of sensitivity to the potential air pollution impact. Land use with reference to the OZP classification type for each ASR has been provided.

3.6.7             In general, ASRs identified as “Residential” (R) or "Government, Institution or Community” (G/IC) would be more sensitive to the potential air pollution impact when comparing to the “Industrial” areas (I).  In addition, areas identified as “Other Specified Uses” (OU) are situated within the container terminal, where the potential air pollution impact is more likely to be dominated by the adjacent marine traffic and cargo terminal operation, instead of the inland road network and this Project in Kwai Chung area, which are remotely located at about 250m away.

Table 33       Representative Air Sensitive Receivers

ASRs ID

Representative ASRs Description

Land Use (i)

Assessment Height (Above Ground) (m) (ii)

Shortest Horizontal Distance to the Project Boundary (m)

Existing /

Planned

A001

Kwai Tsing Theatre

G/IC

1.5 ,5 ,10

246

Existing

A002

Not used

-

-

-

-

A003

Kwai Tsing District Police Headquarters & Divisional Police Station

G/IC

1.5 ,5 ,10

483

Existing

A004

Proposed Residential (Group E) 1 Development at Ex-Kwai Chung Police Married Quarters at Kwai Yi Road

R

1.5 ,5 ,10

448

Planned

A005

Kwai Fong Terrace Block 2

R

16.4 ,19.9 ,24.9

339

Existing

A006

Kwai Yi Road Playground & Sports Ground

O

1.5

290

Existing

A007

Tin Hau Temple

RE

1.5 ,5 ,10

393

Existing

A008

Lai Yiu Estate Fu Yiu House

R

1.5 ,5 ,10

379

Existing

A009

TWGHs Ko Ho Ning Memorial Primary School

G/IC

1.5 ,5 ,10

332

Existing

A010

Kwai Chung Methodist College

G/IC

1.5 ,5 ,10

354

Existing

A011

Lingnam Dr. Chung Wing Kwong Memorial Secondary School

G/IC

1.5 ,5 ,10

78

Existing

A012

Lai King Catholic Secondary School

G/IC

1.5 ,5 ,10

47

Existing

A013

Ho Kwai Chung Polyclinic & Special Education Services Centre

G/IC

1.5 ,5 ,10

131

Existing

A014

Lai King Hill Road North Sitting-out Area

G/IC

1.5

112

Existing

A015

Lai King Estate Wo King House

R

1.5 ,5 ,10

62

Existing

A016

Lai King Estate Fung King House

R

1.5 ,5 ,10

21

Existing

A017

Lai King Estate Ming King House

R

1.5 ,5 ,10

21

Existing

A018

Lai King Estate Yat King House

R

1.5 ,5 ,10

89

Existing

A019

HKEAA Lai King Assessment Centre

G/IC

1.5 ,5 ,10

30

Existing

A020

Lai King Restaurant Playground

O

1.5

46

Existing

A021

Lai King Restaurant

C

1.5 ,5 ,10

32

Existing

A022

Not Used

-

-

-

-

A023

Yuet Lai Court - Lai Hung House (Block D)

R

1.5 ,5 ,10

172

Existing

A024

Yuet Lai Court - Lai Wah House (Block B)

R

1.5 ,5 ,10

230

Existing

A025

Lai King Estate - Yeung King House

R

1.5 ,5 ,10

239

Existing

A026

Lai King Estate - On King House

R

1.5 ,5 ,10

282

Existing

A027

Lai King Estate - Flatted Factories

I

1.5 ,5 ,10

331

Existing

A028

China Holiness College

G/IC

1.5 ,5 ,10

415

Existing

A029

OUHK CITA Learning Centre

G/IC

1.5 ,5 ,10

313

Existing

A030

Lai King Community Hall

G/IC

1.5 ,5 ,10

383

Existing

A031

Asbury Methodist Primary School

G/IC

1.5 ,5 ,10

438

Existing

A032

Mariners' Club

OU

1.5 ,5 ,10

398

Existing

A033

Container Terminal 2 Office

OU

1.5 ,5 ,10

364

Existing

A034

Container Terminal 2 Workshop

OU

1.5 ,5 ,10

324

Existing

A035

Container Terminal 5 Administration Building

OU

16.5 ,20 ,25

276

Existing

A036

Container Terminal 5 Godown

OU

16.5 ,20 ,25

278

Existing

A037

Container Terminal 5 Office

OU

1.5 ,5 ,10

387

Existing

A038

Fidelity Godown

OU

1.5 ,5 ,10

249

Existing

A039

Kerry (Kwai Chung) Godown

I

1.5 ,5 ,10

228

Existing

A040

Cargo Consolidation Complex

I

21.3 ,24.8 ,29.8

226

Existing

A041

Ever Gain Plaza Tower 1

I

47.9 ,51.4 ,56.4

146

Existing

A042

Ever Gain Plaza Tower 2

I

47.9 ,51.4 ,56.4

63

Existing

A043

Kwai Shun Industrial Centre North Tower

I

1.5 ,5 ,10

60

Existing

A044

Golden Industrial Building

I

1.5 ,5 ,10

91

Existing

A045

Kwai Shun Street Cooked Food Market

I

1.5 ,5 ,10

70

Existing

A046

Kwai Shun Street Playground

G/IC

1.5

98

Existing

A047

Kwai Tak Industrial Building Block 2

I

1.5 ,5 ,10

126

Existing

A048

Profit Industrial Building

I

1.5 ,5 ,10

85

Existing

A049

Join-in Hang Sing Centre

I

1.5 ,5 ,10

46

Existing

A050

Petrol Station Office at Container Port Road

OU

1.5 ,5 ,10

40

Existing

A051

Marvel Industrial Building Block B

I

5.5 ,9 ,14

178

Existing

A052

Wing Hang Industrial Building

I

7.5 ,11 ,16

295

Existing

A053

Kwai Shing Swimming Pool

I

1.5 ,5 ,10

499

Existing

A054

Hing Shing Road Basketball Court

I

1.5

440

Existing

A055

Kwai Chung Sports Ground

G/IC

1.5

345

Existing

A056

Kwai Chung Plaza Block 1

R

1.5 ,5 ,10

476

Existing

A057

New Kwai Fong Gardens Block A

R

1.5 ,5 ,10

297

Existing

A058

Hibiscus Park Block 2

R

5.1 ,8.6 ,13.6

498

Existing

A059

Highland Park Block 6

R

3.3 ,6.8 ,11.8

384

Existing

A060

Cho Yiu Chuen Kai Min Lau

R

1.5 ,5 ,10

279

Existing

A061

Cho Yiu Chuen Kai Hang Lau

R

1.5 ,5 ,10

350

Existing

A062

Cho Yiu Chuen Chung Ling Sheh

R

1.5 ,5 ,10

364

Existing

A063

Lai King Estate - Lok King House (Block 7)

R

1.5 ,5 ,10

305

Existing

A064

Wing Hong Factory Building

I

1.5 ,5 ,10

132

Existing

A065

Metroplaza Tower 2

C

1.5 ,5 ,10

348

Existing

A066

Yin Lai Court - Yin Kwong House (Block A)

R

1.5 ,5 ,10

91

Existing

A067

Yin Lai Court - Yin Tak House (Block B)

R

1.5 ,5 ,10

102

Existing

A068

Wah Fung Industrial Centre

I

6.5 ,10 ,15

213

Existing

A069

Fook Yip Building

I

1.8 ,5.3 ,10.3

149

Existing

A070

Lai King Sports Centre

R

1.5

174

Existing

Notes: (i)            R – Residential, I – Industrial, C – Commercial, G/IC – Government / Institution / Community, O – Open Space, OU – Other Specified Uses, T – MTR Station, RE - Religious

             (ii)           The assessment heights are adjusted to the corresponding assessment level or fresh air intake point, such as locations above the following facilities:-

                             -     Car parking podium

                             -     Ground floor lobby

                             -     Shopping centre with non-openable window façade

                  


Identification of Pollution Sources and Key Pollutants

3.6.8             Major sources of air quality impact associated with the operation of the Project include the followings:

·         Vehicular emissions in associated with the operation of the proposed carriageway (the Project).

·         Vehicular emission arising from the existing roads networks within the 500m study area from the Project boundary.

·         Chimney emissions from the nearby factories within the study area.

·         Background air pollution levels for the assessment year (Year 2021) estimated by the PATH model.

 

Vehicular Emission from Open Road

3.6.9             Vehicular emission comprises a number of air pollutants, including Nitrogen Oxides (NOx), Respirable Suspended Particulates (RSP), Sulphur Dioxide (SO2), Carbon Monoxide (CO), Lead (Pb), etc. Motor vehicles are the major causes of high concentrations of RSP and NOx at street level in Hong Kong and these two pollutants are considered as key air quality pollutants for road projects. For other pollutants, due to the low concentration in vehicular emission, they are not considered as key pollutants for the purpose of this study. The characteristics of these pollutants are briefly described below:

Nitrogen Dioxide (NO2)

3.6.10         NOx are major pollutants created by the use of fossil fuel combustion. According to the 2012 Environmental Performance Report published by EPD, road transport is the major NOx contributor of the total emissions. Hence, NO2 is considered as one of the key air pollutants for the operational air quality impact assessment of the Project.

Respirable Suspended Particulates (RSP)

3.6.11         RSP refers to the suspended particulates with a nominal aerodynamic diameter of 10µm or less. According to the 2012 Environmental Performance Report published by EPD, road transport is the second largest RSP contributor of the total emission. Hence, RSP is also considered as a key air pollutant for the operational air quality assessment of the Project.

Fine Suspended Particulates (FSP)

3.6.12         FSP refers to the suspended particulates with a nominal aerodynamic diameter of 2.5µm or less, which can be suspended in the air and cause adverse impact to the human health. FSP is newly introduced in the prevailing AQO effective from January 2014. Hence, FSP is one of the key pollutants for the operational air quality assessment of the Project.

Sulphur Dioxide (SO2)

3.6.13         SO2 is formed primarily from the combustion of sulphur-containing fossil fuels. SO2 emission from vehicular exhaust is due to the sulphur content in diesel oil. According to EPD’s “Cleaning the Air at Street Level”, ultra low sulphur diesel (ULSD) with a sulphur content of only 0.005% has been adopted as the statutory minimum requirement for motor vehicle diesel since April 2002. With the use of ULSD, according to the 2011 Environmental Performance Report released by EPD, road transport is the smallest share of SO2 emission sources in 2009 and only constitutes 0.5% of the total SO2 emission.  From 1 July 2010, EPD has tightened the statutory motor vehicle diesel and unleaded petrol specifications to Euro V level, which further tightens the cap on sulphur content from 0.005% to 0.001%. Road transport is therefore anticipated only a very small amount of SO2 emission contribution. With the adoption of low-sulphur and ultra-low-sulphur fuel under the existing government policy, SO2 is not a critical air pollutant of concern.

Carbon Monoxide (CO)

3.6.14         CO is a typical pollutant emitted during fossil fuel combustion and comes mainly from vehicular emissions. With reference to the “Air Quality in Hong Kong 2012”, the highest 1-hour average (2,670µg/m3) and the highest 8-hour average (2,345µg/m3) were both measured at the Tsuen Wan station; these values were around 8.9% and 23.5% of the respective AQOs.  In view that there is still a large margin to the AQOs, CO would not be a critical air pollutant of concern. 

Ozone (O3)

3.6.15         O3 is produced from photochemical reaction between NOx and Volatile Organic Compounds (VOCs) in the presence of sunlight. Concentration of O3 is governed by both precursors and atmospheric transport from other areas. When precursors transport along under favorable meteorological conditions and sunlight, O3 will be produced. This explains why higher O3 levels are generally not produced in the urban core or industrial area but rather at some distance downwind after photochemical reactions have taken place. In the presence of large amounts of NOx in the roadside environment, O3 reacts with NO to give NO2 and thus results in O3 removal. As it takes few hours for these photochemical reactions to take place, O3 recorded in one area could be attributed to VOCs and NOx emissions from another area, which may be distant from the project site. Hence, O3 is a regional air pollution problem and is not a primary pollutant emitted from vehicular emissions. O3 is therefore not considered as a key air pollutant for the operational air quality assessment of a road project.

Lead (Pb)

3.6.16         The sale of leaded petrol has been banned in Hong Kong since April 1999. According to the “Air Quality in Hong Kong 2012”, the measured ambient Pb concentrations were ranging from 11ng/m3 to 57ng/m3. The measured concentrations were well below the AQO.  Therefore, lead is not considered as a critical air pollutant of concern.

3.6.17         In this Project, the major pollutant sources are from vehicular emissions. Among the pollutants mentioned above, NO2, RSP, and FSP are the major air pollutants that would be generated. The time averaged concentrations of these pollutants are calculated and assessed as stipulated in the prevailing AQOs. All road links included in this assessment are illustrated in Figure 3.2 while traffic flow data can refer to Appendix 3-2.

3.6.18         It is identified that only the road links listed below have changes in traffic volume and travelling speed between the “With Project” and “Without Project” scenarios as shown in Figure 3.3:

·      58S - Kwai Chung Road

·      92S - Tsuen Wan Road

·      93S - Kwai Chung Road

·      94S2 - Kwai Chung Road

·      95S - Kwai Chung Road

·      96S - Flyover from Kwai Tsing Interchange to Kwai Chung Road

3.6.19         From the traffic forecast of “With Project” and “Without Project” scenarios in Year 2021, it is anticipated that the total traffic volume will remain unchanged and there will be no additional increase in traffic flow drawn by the Project. Instead, traffic congestion and travelling speed will be improved after the implementation of the Project. In view of these, it is unlikely that additional adverse air quality impacts would be induced by the proposed project to the existing environment. The comparisons of traffic flows and traffic speeds between “With Project” and “Without Project” scenarios on the above identified roads sections in concern are shown in Table 3‑4 below.

            Table 34        Comparison of Road Traffic Flows and Traffic Speeds between “With Project” and “Without Project” Scenarios

Road ID

Road Name

Section

Bound

Year 2021

"Without Project”

Scenario

Year 2021 Design

“With Project”

Scenario

Daily Total Traffic

Traffic at Peak Hour

Traffic Speed at Peak Hour

Daily Total Traffic

Traffic at Peak Hour

Traffic Speed at Peak Hour

58S

Kwai Chung Rd

Under Tsing Kwai Highway

SB

72,051

5,220

55.48

71,860

5,218

55.50

92S

Tsuen Wan Rd

KT I/C Upramp - KCR Upramp

SB

72,765

5,272

30

54,055

3,917

47.67

93S

Kwai Chung Rd

Flyover from KT I/C upramp - KCR

SB

13,302

960

70

31,821

2,313

54.54

94S2

Kwai Chung Rd

TWR - Tsing Kwai Highway Upramp

SB

58,749

4,260

43.66

40,039

2,905

57.74

95S

Kwai Chung Rd

Tsing Kwai Highway - KCR

SB

58,749

4,260

43.66

40,039

2,905

57.74

96S

Flyover from KT I/C to Kwai Chung Rd

KT I/C - KCR

SB

-

-

-

18,710

1,355

49.03

 

Industrial Chimney Emissions

3.6.20         As mentioned in Section 3.3, the project site is located in the vicinity of the major industrial area in Kwai Chung District, industrial chimney emissions is one of the major sources of air quality impact in the project site.

3.6.21         The chimney inventory is mainly developed with reference to the previous EIA study “Tsuen Wan Bypass, Widening of Tsuen Wan Road between Tsuen Tsing Interchange and Kwai Tsing Interchange and Associated Junction Improvement Works” (EIA-152/2008).

3.6.22         Site visits were conducted in September 2013, in order to update and validate the chimney information. In addition, chimney survey was carried out within the study area to collect updated information of chimney emissions. Details of the site visits and chimney surveys are shown in Appendix 3-3. There are 5 chimneys identified within the study area. Locations of these chimneys are illustrated in Figure 3.4.

 

Determination of Worst Assessment Year in Air Quality Impact Assessment

3.6.23         According to EIA Study Brief ESB-242/2012, the air pollution impacts of future road traffic shall be calculated based on the highest emission strength from the road within the next 15 years upon commencement of operation of the Project (i.e. Year 2021 to 2036).

3.6.24         In order to identify the worst assessment year, the trend of emission inventory from Year 2021 to 2036 was studied by using EMFAC-HK V2.6, under “Without Project” and “With Project” scenarios.  The emission inventory for NOx, RSP and FSP under “Without Project” and “With Project” scenarios are shown in Table 3‑5 and Table 3‑6 respectively.  The corresponding road types are illustrated in Figure 3.2.

3.6.25         The results indicate that there is a trend with decreasing emissions of NOx, RSP and FSP from Years 2021 to 2036 for different types of vehicles under both scenarios. Total emissions of NOx contributing from all road types within the study area are predicted.  Take urban trunk road as example, predicted NOx level would drop by about 42% from Years 2021 to 2029, and 44% from Years 2029 to 2036. On the other hand, RSP and FSP emissions do not show a significant drop from Years 2021 to 2029, but a drop of around 40% from Years 2029 to 2036.

3.6.26         Comparing the predicted trend of emissions of NOx with that of RSP and FSP, NOx emission from the urban trunk road under “With” Project shall be reduced from Year 2021 onward, while RSP and FSP emissions shall be increased by 1% to 2% in Year 2029 and 2036. This slight rising emission trend of RSP and FSP is mainly due to the increase of vehicular travelling speed under “With” Project scenario, when the traffic congestion has been relieved when this Project is in place.

3.6.27         From the EMFAC analysis, the optimal vehicular travelling speed for the least RSP and FSP emission is around 40km/h. When the speed is faster than 40km/h, a positive growing relationship between the RSP/FSP emission and the vehicular travelling speed has been observed.

3.6.28         Notwithstanding such slight increase in RSP/FSP emission under “With” Project scenario, the predicted RSP and FSP concentrations are well within the AQOs based on the results presented in Section 3.6.105, and thus it is not of the primary concern in this project.

Table 35       Total Emission Inventory for “Without” Project Scenario

Year

Total Emission (g/day)

Expressway

Urban District Distributor

Urban Local Distributor

Urban Primary Distributor

Urban Trunk Road

NOx

2021

110154.8

71299.1

54890.5

24772.3

87413.3

2029

77078.7

50379.3

36765.0

17294.4

51095.0

2036

46569.2

29662.5

22999.3

9945.4

28462.6

RSP

2021

4432.3

2257.2

1959.3

804.5

3001.2

2029

4608.3

2216.2

1903.4

826.2

2594.4

2036

2746.2

1410.2

1217.7

497.7

1540.2

FSP

2021

4075.1

2071.4

1798.9

739.5

2757.7

2029

4242.0

2039.2

1751.4

760.4

2386.6

2036

2529.7

1299.2

1121.9

458.3

1418.1

 

Table 36       Total Emission Inventory for “With” Project Scenario

Year

Total Emission (g/day)

Expressway

Urban District Distributor

Urban Local Distributor

Urban Primary Distributor

Urban Trunk Road

NOx

2021

110154.8

71299.1

54890.5

24772.3

83537.3

2029

77078.7

50379.3

36765.0

17294.4

50285.5

2036

46569.2

29662.5

22999.3

9945.4

28081.7

RSP

2021

4432.3

2257.2

1959.3

804.5

2934.7

2029

4608.3

2216.2

1903.4

826.2

2643.8

2036

2746.2

1410.2

1217.7

497.7

1557.5

FSP

2021

4075.1

2071.4

1798.9

739.5

2696.7

2029

4242.0

2039.2

1751.4

760.4

2431.7

2036

2529.7

1299.2

1121.9

458.3

1433.9

 

Table 37       Predicted Total Traffic Volume in Assessment Years

     Road Type

 

 

 

Year

Total Traffic Volume per Day

Expressway

Urban District Distributor

Urban Local Distributor

Urban Primary Distributor

Urban Trunk Road

Total

2021

749642

523783

550249

186247

517496

2527417

2029

786216

548924

576138

195180

542534

2648992

2036

819635

571931

599874

203389

565488

2760317

 

 

3.6.29         Despite of the growth in traffic volume in the assessment year as shown in Table 3‑7 above, the vehicular emission is decreasing. The decreasing trend of NOx, RSP and FSP emissions from Years 2021 to 2036 is mainly due to the government’s air quality improvement policies/programmes. The major vehicle exhaust emission control programmes included in EMFAC-HK V2.6 are:

·      The tightening of vehicle emission standards for first-registered vehicles;

·      The particulate removal device retrofit programme for pre-Euro diesel vehicles and Euro I franchised buses;

·      The introduction of ultra-low sulphur diesel;

·      I/M program using remote sensing and dynamometer testing for petrol/ LPG vehicles;

·      Mandatory retirement of pre-Euro IV diesel commercial vehicles including ex-gratia payment, mandatory retirement of pre-Euro IV diesel commercial vehicles in phases and the 15-year limit on service life of new diesel commercial vehicles;

·      Retrofitting franchised buses with selective catalytic reduction (SCR) Devices; and

·      Subsidy programme for the replacement of catalytic converters and oxygen sensors on LPG/petrol taxi and LPG light bus.

 

3.6.30         NOx consist of nitrogen monoxide (NO), nitrogen dioxide (NO2) and nitrous oxide (N2O), and it is the major pollutant that would be generated from the vehicular emissions. RSP and FSP would also be generated from the vehicular emissions. However, their daily emissions are comparatively smaller than the NOx daily emissions. As mentioned in Section 3.4, annual average NO2 concentration remains high in the existing environment and it exceeds the AQO. Hence NO2 is the pollutant of primary concern among all other pollutants in this study.

3.6.31         In this connection, Year 2021 was selected as the worst assessment year in terms of on-road vehicular emission, within 15 years after the Project commencement.

 

 

Projected Background Air Quality Result of Year 2021 by PATH Model

3.6.32         PATH is a regional air quality model developed by EPD to simulate air quality over Hong Kong against the Pearl River Delta (PRD) as background. For EIA applications, it simulates wind field, pollutant emissions, transportation and chemical transformation and outputs pollutant concentrations over Hong Kong and the PRD region at a fine grid size of 1.5km. PATH model has been adopted in different EIAs projects for projecting background air quality in the future years within the study area.  In the Project, available PATH data are Year 2015 and 2020.

3.6.33         In order to incorporate the updated marine vessel information and to avoid the double counting effects of vehicular emissions, a re-run of the PATH model for the Year 2021 has been conducted for the background air quality concentrations within the study area. The re-run was based on the PATH emission inventory for Year 2020 as shown in Appendix 3-4 while the assumptions were shown in Appendix 3-5.

3.6.34         In this study, the 500m study area covers 4 grids of PATH model, including grids (25, 30), (25, 31), (26, 30) and (26, 31) as shown in Figure 3.5.  A summary of the projected background concentrations in Year 2021 is shown in Table 3‑8 below.  It shows that the 1-hour and annual NO2 background level marginally comply with the AQOs, especially at grids (25, 30) and (25, 31), in which local vehicular emissions contributed by the road network and this Project at Kwai Chung area have not been taken into account.

Table 38       Summary of Predicted Results from PATH Model in Year 2021

Pollutant

Averaging Time

Concentration Limits in AQOs (µg/m3) (i)

Year 2021 PATH Model Concentration (µg/m3) (ii)

Grid (25,30)

Grid (25,31)

Grid (26,30)

Grid (26,31)

RSP

24-hour

100 (9)

100 [1]

97 [0]

98 [0]

96 [0]

Annual

50

43

41

40

40

FSP

24-hour

75 (9)

77 [1]

75 [0]

76 [1]

74 [0]

Annual

35

31

29

29

28

Nitrogen Dioxide (NO2)

1-hour

200 (18)

244 [10]

234 [12]

241 [6]

238 [6]

Annual

40

39

30

29

26

Notes: (i)             The numbers in brackets ( ) refer to number of exceedances allowed per year.

(ii)           The numbers in brackets [ ] refer to number of exceedances of the background concentration.

 

Assessment Methodology

3.6.35         The overall methodology for the air quality impact assessment within study areas is as follows:

·         EMFAC-HK is adopted to determine the emission factors for 16 vehicular classes, details are shown in Appendix 3-6.

·         Use of near field dispersion model (i.e. CALINE4) for open road sources within the study area including adjacent road networks.

·         Use of near field dispersion model (i.e. ISCST3) for volume sources to quantify the air quality impacts at local scale from sources including emissions from noise enclosure portals.

 

Determination of Vehicular Emissions from Open Roads

3.6.36         CALINE4 model was developed by US Environmental Protection Agency (USEPA) and is commonly adopted to estimate the vehicular emissions from the open road sources. The hourly emission rates of each vehicle class (in g/VMT) and each road section have been determined using the emission factors obtained from the EMFAC-HK model, in which the consideration of the hourly traffic flow and the distance travelled had been included.  The composite vehicular emission factor for each road link in the assessment Year 2021 is given in Appendix 3-7.

3.6.37         Refer to Section 3.6.22 – Section 3.6.34, PATH model results were adopted as the background concentrations for different pollutants in grids (25, 30), (25, 31), (26, 30) and (26, 31). Four different sets of MM5 hourly meteorological data were adopted for the assessment in the corresponding grids. The pollution impacts at ASRs have been estimated using CALINE4 and ISCST3 models and the corresponding 1-year hourly MM5 data, which fall within the same grid of the ASRs.

3.6.38         The stability classes were calculated using PCRAMMET model issued by USEPA.

3.6.39         With the generation of stability class data, a full set one year meteorological data extracted from MM5 data, including the followings were adopted in the CALINE4 model:

·      Temperature

·      Wind speed

·      Wind direction

·      Stability class

·      Mixing height

·      Surface roughness (Z0): 370cm.

·      Standard deviations for different stability classes: s × (Z0/15 cm)0.2

where            Stability Class A (sA)    = 22.5°

Stability Class B (sB)     = 22.5°

Stability Class C (sC)     <