8.                   Air quality impact

Introduction

8.1               Potential air quality impacts associated with the construction and operation phases of the Project are presented in this section.   Representative Air Sensitive Receivers (ASRs) have been identified.  The potential air quality impacts on these receivers likely to result from the construction and operation of the Project have been identified and evaluated.  Potential impacts have been avoided wherever possible and appropriate mitigation measures have been proposed to minimise the potential air quality impact. 

Environmental Legislation, Standards and Guidelines

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

Air Quality Objective & EIAO-TMs

8.3               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 (AQOs), which must be satisfied, stipulate the maximum allowable concentrations over specific periods for typical pollutants.  The relevant AQOs are listed in Table 8.1.

Table 8.1          Hong Kong Air Quality Objectives

Pollutant

Maximum Concentration (µg m-3) (1)

Averaging Time

1 hour (2)

8 hour (3)

24 hour (3)

Annual (4)

Total Suspended Particulates (TSP)

-

-

260

80

Respirable Suspended Particulates (RSP) (5)

-

-

180

55

Sulphur Dioxide (SO2)

800

-

350

80

Nitrogen Dioxide (NO2)

300

-

150

80

Carbon Monoxide (CO)

30,000

10,000

-

-

Photochemical Oxidants

(as Ozone, O3) (6)

240

-

-

-

Note:

(1)              Measured at 298 K and 101.325 kPa.

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

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

(4)              Arithmetic mean.

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

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

 

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

Air Pollution Control (Construction Dust) Regulation

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

Description of the Environment

8.6               The Project site is located within the existing Ocean Park area in Aberdeen on the southern side of Hong Kong Island.  The existing park is built on the northern and southern sides of Nam Long Shan, and comprises three parts: Lowland, Headland and Tai Shue Wan.  The Lowland lies at the northern side of Nam Long Shan, and is adjacent to Wong Chuk Hang Road (the main access to Ocean Park) and Ocean Park Road. To the south of the site are coastal waters.

8.7               The potential air quality pollutant sources in the study area include traffic road emissions and industrial emissions from Wong Chuk Hang.

8.8               There is no EPD air quality monitoring station located in the vicinity of the Project site, so the background pollutant concentrations to be adopted for the Project site have therefore been derived from data for “Rural/ New Development” areas such as Shatin, Tai Po and Yuen Long, as recommended in the EPD “Guideline on Assessing the ‘Total’ Air Quality Impacts”.

8.9               The latest five years (1999 – 2003) average monitoring data for similar type of development area including Shatin, Tai Po, Yuen Long, Tap Mun and Tung Chung (adopted to represent the background air quality in this project) are presented in Table 8.2.

Table 8.2          Background Air Pollutant Concentration for the Study Area

Parameters

Concentration (mg/m3)

TSP

75 (1)

RSP

50 (1)

Nitrogen Dioxide

43 (1)

Sulphur Dioxide

15 (1)

                Note:

(1) 5-year average background level measured at Shatin, Tai Po, Yuen Long, Tap Mun and Tung Chung EPD Air Quality Monitoring Stations.

 

Air Sensitive Receivers

8.10            The two main project sites would be on northern (The Waterfront) and southern (The Summit) sides of Nam Long Shan.  The study area for air quality impact assessment was defined by a distance of 500 m from the boundary of the project site and is shown in Figure 8.1.  In accordance with Annex 12 of the EIAO-TM, representative existing and planned air sensitive receivers (ASRs) in proximity to the project site were selected for air quality impact assessment.  At The Summit, the ASRs would be the visitors within Ocean Park itself, whilst the representative ASRs in the vicinity of The Waterfront are listed in Table 8.3 and their locations are illustrated in Figure 8.2.

8.11            The air quality impacts at ground floor of the representative ASRs, which is the average height of the human breathing zone, were assessed in the study.  Assessment heights of 5m and 10m were also selected to show the vertical variation of the pollutant concentrations (during operation phase of the project).  Additionally, higher assessment heights were also selected to show the vertical variation of the sulphur dioxide concentrations during operation of the project.  As there is no air pollutant emission sources found in and around the Summit and the chimneys in Aberdeen / Wong Chuk Hang are located far away (at least 1 km), no adverse air quality impact would be expected at the Summit. 

 

Table 8.3          Summary of Representative Air Sensitive Receivers

ASR

Description

Land Uses

Existing / Planned NSR

No. of storey

Ground Level

(mPD Level

Assessment Height (mAG)

Horizontal Separation from Site Boundary

(m)

AL1

Grantham Hospital

Hospital

Existing

8

32

1.5, 5, 10

300

AL2

Wong Chuk Hang Hospital

Hospital

Existing

8

10.2

1.5, 5, 10

240

AL3

Wong Chuk Hang San Wai

Residential

Existing

2

10

1.5, 5, 10

160

AL4

Wong Chuk Hang San Wai

Residential

Existing

2

10

1.5, 5, 10

80

AL5

The Hazelton

Residential

Existing

3

22

1.5, 5, 10

40

AL6

Country Villa

Residential

Existing

3

22

1.5, 5, 10

25

AL7

Bay Villas

Residential

Existing

3

34

1.5, 5, 10

25

AL8

Island View

Residential

Existing

2

22

1.5, 5, 10

140

AL9

Manly Villa

Residential

Existing

3

92

1.5, 5, 10

80

AL10

Old Teaching Block (Police Training School)

Educational Institution

Existing

4

10.2

1.5, 5, 10

80

AL11

Inspectorate Married Quarters

Residential

Existing

10

25.5

1.5, 5, 10

40

AL12

Open Area of Police Training School

Residential

Existing

-(1)

6

1.5, 5, 10

15

AL13

Aberdeen Sports Ground

Recreational

Existing

-(1)

9

1.5, 5, 10

80

AL14

Proposed Entry Plaza of Ocean Park (2)

Commercial

Planned

-(1)

8

1.5, 5, 10, 20(3), 40(3) 60(3), 70(3), 80(3) 100(3)

-(2)

AL15

Office near Cable Car Station (2)

Commercial

Existing

-(1)

18

1.5, 5, 10, 20(3), 40(3) 60(3), 70(3), 80(3) 100(3)

-(2)

AL16

Tennis Court adjacent to Wong Chuk Hang Road

Recreational

Existing

-(1)

17.7

1.5, 5, 10

10

AL17

The Hong Kong Country Club

Recreational

Existing

-(1)

17.6

1.5, 5, 10

10

AL18

St. Paul’s Co-educational Primary School

Educational Institution

Planned

6

19.5

1.5, 5, 10

445

AL19

Woodgreen Estate

Residential

Existing

3

27.5

1.5, 5, 10

170

AL20

Beaconfield Court

Residential

Existing

3

21.9

1.5, 5, 10

180

AL21

Xanadu Court

Residential

Existing

3

27.8

1.5, 5, 10

100

                Note:

(1)     N/A

(2)     ASR located within Ocean Park

(3)     Additional assessment heights were selected for assessing SO2 emission from chimneys.

Identification of Pollutant Sources

Construction Phase

8.12            Potential impacts arising from the construction of the proposed Project would include dust and gaseous emissions from construction plant and vehicles. It is anticipated that dust would be generated from activities such as stockpiling, blasting, demolition, excavation, materials handling, vehicular movements on unpaved haul roads and wind erosion from the site.  However, the only major dusty activities would be site formation, excavation works and blasting.

8.13            The proposed construction works at The Waterfront and The Summit would be carried out in phases and the associated construction activities are described as follows:

The Waterfront

8.14            There are 6 main construction sites at The Waterfront.  The main construction activities include site clearance, demolition, site formation, piling works and superstructure construction.  The major dusty construction activities would be excavation and site formation.  The tunnel excavation works for the funicular railway, however, would take place mostly within the tunnel and so should not result in dust major impacts.  For the other sites, the periods planned for excavation/ site formation are as follows (refer to construction programme, Appendix 2.2).

Birds of Paradise – June to July 2006

Entry Plaza – November 2006 to January 2007

Aqua City – April 2007 to September 2007

Whisker’s Harbour – May 2008

Back of House – April to May 2008

8.15            As the construction works are phased, it can be seen that the major dusty construction activities at these sites would not take place concurrently, except for site formation at Whisker’s Harbour and Back of House.  However, the overlapping period would last for only one month.  The cumulative dust impact is therefore of short-term nature, and with the implementation of appropriate dust suppression measures, would be unlikely to cause adverse impacts.

The Summit

8.16            Apart from excavation of the summit itself and the spoil handling facility/ barging point located at Tai Shue Wan (both addressed below), there are 6 construction sites at the Summit.  The main construction activities would include site clearance, excavation, piling works, drainage & sewerage works and superstructure construction.  The major dusty construction activities would be excavation and site formation.  As for the waterfront area, excavation of the funicular railway would occur in tunnel and would not result in major dust generation. For the other sites, the periods planned for excavation/ site formation are as follows (refer to construction programme, Appendix 2.2).

Vet Hospital – June 2006 to October 2006

Thrill Mountain and Rainforest – October 2007 to December 2007

Polar Adventure – May 2008 to July 2008

Killer Whale Stadium – May 2009 to November 2009

Marine World – January 2009 to March 2009

 

8.17            As the construction works are phased, the major dusty construction activities at different sites would not take place concurrently.  Therefore, cumulative dust impact is not expected.  With the adoption of dust suppression measures and provision of a buffer zone between the construction areas and the visitor areas, adverse construction dust impacts are not expected.

8.18            Excavation of the Summit to form a series of level platforms from +180mPD to about +140mPD (see Figure 3.4) could result in substantial dust generation.  Drilling and blasting would be the only viable option for rock breaking given the quantity of rock and programme constraints.

8.19            However, in order to avoid dust impact to the Park visitors, blasting would take place only in the early morning prior to the opening of the Park.  Therefore Park visitors would not be affected by dust from blasting.  In addition, the closest ASRs are located at a considerable distance from the site (at least 350 m away) and with appropriate mitigation measures, adverse dust impact are not expected to occur.

8.20            The excavated rock will need to be removed from the site after blasting.  In view of the potential for dust impacts along the transportation route, a tunnel will be formed and excavated material will be fed down the drop shaft and conveyed along a horizontal adit (the so-called “glory-hole” excavation method).  From the entrance to the tunnel adit, excavated material will be transported by covered conveyor belt system to a marine barging point with enclosed tipping hall at Shum Wan Road.  An illustrative section showing the glory hole method for excavation and conveyor belt system is shown in Figure 3.5 and Figure 3.6 respectively.  The conveyor belt would run inside a steel enclosure. The tipping hall of the barging point would be enclosed and the excavated materials would be transported via the enclosed chute into the barge.  Flexible curtain would also hang on the chute to prevent the dust impact, and dust sprays would be applied where necessary at offloading points.   There will be a temporary mobile crusher located in the vicinity of the adit to crush the rock-cut materials.  The fabric filters would be installed for the crushing plant as well as water spraying on the crusher.  If the processing capacity of the crushing plant exceeds 5000 tonnes per annum, it would be necessary to apply for a specified process (SP) licence under the APCO.  The conditions and mitigation measures stipulated in the SP license will be followed and will be implemented.  With the implementation of the above dust suppression measures, dust impact is not expected to occur at any ASRs.

Operational Phase

8.21            The major air pollutant sources during operational phase of the Project would be vehicular emissions (in particular NO2 and respirable suspended particulates, RSP) from additional traffic induced by the operation of the new park.  Emissions from existing roads and industrial emissions from the existing Wong Chuk Hang industrial buildings, as well as from the hospitals within 500 m from the study area, and portal emissions and emission from exhaust ventilation shaft of the existing Aberdeen Tunnel, would contribute to cumulative air quality impact.

Assessment Methodology

Construction Phase

8.22            As the construction activities would be phased, it is expected that, with implementation of dust suppression measures as stipulated in the Air Pollution Control (Construction Dust) Regulation and proposed mitigation measures stipulated in section 8.42 - 8.46, significant dust impact would not arise.  A qualitative approach to evaluate the air quality impact pertinent to the construction of the Project is therefore adopted.

Operational Phase

8.23            Potential air quality impacts have been considered for two scenarios: (i) future operation of Ocean Park without redevelopment and (ii) future operation of redeveloped Ocean Park.

Emission Inventory

Vehicle Emissions from Open Roads

8.24            The peak hourly traffic flows induced from the operation of the Project occurring within 15 years of the park without development or redeveloped park opening, i.e. Year 2026 traffic flows, were used to predict the worst case scenario in the future.

8.25            A sensitivity test was conducted to determine whether the worst air quality scenario would occur on a weekday or on a Sunday/ Public Holiday.  The worst case was determined in terms of the traffic flow and emission factors, for major roads in the year 2026 with redeveloped park and the park without development (refer to Appendices 8.1a and 8.1b).  Results indicate that the worst scenario in terms of air pollution from vehicle emissions would occur on a Sunday/ Public Holiday P.M. peak in year 2026.  Therefore, projected Year 2026 P.M. traffic flows on Sunday/ Public Holiday (maximum traffic flow induced by the operation of the Park within 15 years of commencement of the Project and maximum traffic flow inducted by the operation of the Park without re-development) were adopted for the assessment of future scenarios.

8.26            The vehicular emission factors (Fleet Average Emission Factors – EURO4 Model) for the year 2026 were adopted for assessment of the future scenarios (park without development and re-developed park).  The composite emission factors for the road links were calculated as the weighted average of the emission factors of different types of vehicle.  As emission factors beyond 2011 are not available, the 2011 vehicle emission factors have been used for traffic beyond 2011 as a worst-case scenario.  Details for the calculations of the composite emission factors for each road link are given in Appendices 8.2a and 8.2b.

8.27            All major roads within 500m of the project development were incorporated into the assessment.

8.28            According to information provided by the Traffic Consultants, there was no queue found on Sunday/ Public Holidays.  Therefore, emission from idling vehicles near the Aberdeen toll plaza during the peak hour flow was not included in the assessment.

Emissions from Portal and Ventilation Shaft of Aberdeen Tunnel

8.29            The proportion of traffic emissions expelled from the portals and the vent shaft(s) of a vehicular tunnel depends on the ventilation design of the tunnel. Aberdeen Tunnel is a 1.85 km twin-tube tunnel with four ventilation shafts.  The ventilation shafts are located at each end of northbound and southbound tunnel (i.e. two ventilation shafts at Aberdeen side and two ventilation shafts at Wan Chai side).  Within the study area, emissions from the ventilation shafts and the portals at the Aberdeen side of the tunnel were considered in the assessment.  The two ventilation shafts were assumed to be operated 24 hours a day.  Details of the tunnel and ventilation shafts are summarised in Table 8.4.  Detailed calculation for portal emissions and the figure showing locations of the two ventilation shafts are presented in Appendix 8.3.

Table 8.4          Details of Aberdeen Tunnel and Ventilation Shafts

Tunnel Length

1.85 km

Carriageway

6.75 m

Height of Ventilation Shaft

5.5 m

Intake Volume of each Ventilation Shaft

212.5 m3/s

Exhaust Volume of each Ventilation Shaft

150 m3/s

Exit Direction

Upward

Exit Velocity

12.6 m/s

Portal Emission for each carriageway direction

29.41% *

            Note: * Calculated based on the given flow rate from Aberdeen Tunnel Management Company.

Emission from Industrial Buildings and Hospitals

8.30            Emissions from the industrial buildings at Wong Chuk Hang and hospitals at Nam Long Shan area would contribute to the cumulative impact of nitrogen dioxide (NO2).  Air quality impacts due to these emissions in the vicinity of Ocean Park have been considered in the assessment.  The inventory of industrial chimneys maintained by EPD (received in September 2005) was used to assess the impacts from the chimney emissions.  A total of 12 active diesel oil-fired furnaces were identified within 1km radius of the subject site from EPD’s register.  The locations of the chimney are shown in Appendix 8.4.

8.31            The emission factor for NOX was based on AP42 (USEPA 1998: Table 1-3-1 Criteria Pollutant Emission Factors for Fuel Oil Combustion).  For calculation of the NO2 concentrations, the conversion factor from NOX to NO2 was assumed (conventionally) to be 20%.  The calculation of chimney emission factor is shown in Appendix 8.4.

Dispersion Modelling

Vehicle Emissions from Open Roads

8.32            The CALINE4 dispersion model was used to calculate the hourly NO2, 24-hour NO2 and 24-hour RSP concentrations.  For calculation of the NO2 concentrations, the vehicular emission factor for NOx was used and the conversion factor from NOx to NO2 was assumed (conventionally) to be 20%.

8.33            The USEPA publication: Screening Procedures for Estimating the Air Quality Impact of Stationary Source (EPA-454/R-92-019), recommends a conversion factor of 0.4 to convert hourly average concentrations into daily (24 hour) average concentrations.  This conversion factor was used in the assessment.

8.34            The worst-case scenario of neutral meteorological conditions was assumed in the CALINE4 model.

·               Wind speed:                     1 m/s

·               Wind direction:                 360 wind direction

·               Wind variability:                18o

·               Stability class:                  D

·               Surface roughness:           1 m

·               Mixing height:                   500 m

·               Temperature                     25 °C

 

8.35            Portal emissions from the Aberdeen Tunnel were calculated based on the procedures in Section III of the Permanent International Association of Road Congress Report (PIARC), 1991.  It was assumed that emissions would emerge as an air jet along the axis of the road so that only the well-diluted parts gradually shear off.  The pollutants were assumed to be ejected as a volume source in the model, with two-thirds of the total emissions dispersed in the first 50m, and one third of the total emissions dispersed in the second 50m.  The portal emissions were modelled as volume sources in the ISCST3 model.

Chimney Emissions and Ventilation Shaft Emissions from Aberdeen Tunnel

8.36            Emissions (NO2 & SO2) from chimneys and emissions (NO2) from the ventilation shafts of the Aberdeen Tunnel were modelled as point sources employing the Industrial Source Complex Short-Term (ISCST3) dispersion model.  The meteorological conditions used in the ISC3 model were the same as those used in the CALINE4 model.

Concentration Calculation

8.37            To obtain the cumulative pollutant concentrations, a set of 360 values was derived from both the CALINE4 model and the ISCST3 model at each receptor location (one value for each of the 360 wind directions).  The highest value among the 360 wind directions of each set values were identified and then added together (regardless of wind direction), the resulting value was considered to be the highest predicted pollutant concentration level at the receptor.

8.38            Background pollutant concentrations were added to the results calculated above to produce the worst-case concentrations. 


Evaluation of Impacts

Construction Phase

8.39            The construction activities would be phased, and the blasting activities would be undertaken in early morning before the opening of the Park. The conveyor system would be operated in enclosed area.  With the implementation of standard dust suppression measures as stipulated in the Air Pollution Control (Construction Dust) Regulation and recommended measures in Section 8.42, there would be no adverse dust impacts on the ASRs in the vicinity of the construction sites.  Additionally, an environmental monitoring and audit programme will be implemented during construction to ensure all the proposed mitigation measures would be properly in place.

Operational Phase

8.40            The predicted average NO2, RSP and SO2 concentrations at the representative ASRs are summarized in Tables 8.5 to 8.7.  The predicted concentrations are the cumulative result of emissions from:

·               Open road sections

·               Aberdeen Tunnel portals

·               Aberdeen Tunnel Ventilation Shafts

·               Chimney emissions in the Wong Chuk Hang and Nam Long Shan Area.

Table 8.5          Predicted Air Pollutant Concentrations at Representative ASRs for the Future Scenario (Year 2026, Redeveloped Park)

ASR ID

Assessment Height

(metres AGL)

Hourly Averaged NO2 concentration (mg/m3)

24-Hour NO2 Averaged concentration (mg/m3)

24-Hour RSP Averaged concentration (mg/m3)

AL1

1.5

141

82

63

5

139

82

63

10

133

79

62

AL2

1.5

155

88

65

5

152

87

64

10

145

84

64

AL3

1.5

185

100

69

5

180

98

68

10

169

93

67

AL4

1.5

150

86

64

5

147

85

64

10

138

81

63

AL5

1.5

158

89

65

5

149

85

64

10

132

79

62

AL6

1.5

173

95

67

5

145

84

63

10

124

76

61

AL7

1.5

145

84

63

5

135

80

62

10

120

74

60

AL8

1.5

99

65

57

5

99

65

57

10

97

64

57

AL9

1.5

77

57

54

5

77

57

54

10

76

56

54

AL10

1.5

100

66

57

5

98

65

57

10

94

64

57

AL11

1.5

84

60

55

5

84

59

55

10

83

59

55

AL12

1.5

116

72

60

5

113

71

59

10

106

68

58

AL13

1.5

130

78

61

5

128

77

61

10

124

75

61

AL14

1.5

126

76

61

5

125

76

61

10

120

74

60

AL15

1.5

112

71

59

5

110

70

59

10

105

68

58

AL16

1.5

102

67

58

5

101

66

58

10

98

65

57

AL17

1.5

89

61

56

5

89

61

56

10

88

61

56

AL18

1.5

284

140

82

5

261

130

79

10

200

106

71

AL19

1.5

148

85

64

5

146

84

64

10

139

81

63

AL20

1.5

164

91

66

5

161

90

66

10

152

86

64

AL21

1.5

153

87

65

5

126

76

61

10

107

69

58

Notes:

(1) Value in bold type indicates that the NO2 concentration exceeds the HKAQO.

(2) Background NO2 concentration of 43 mg/m3 and RSP concentration of 50 mg/m3 are included.

 

Table 8.6          Predicted Air Pollutant Concentrations at Representative ASRs for the Future Scenario (Year 2026, Park without Development)

ASR ID

Assessment Height

(metres AGL)

Hourly Averaged NO2 concentration (mg/m3)

24-Hour NO2 Averaged concentration (mg/m3)

24-Hour RSP Averaged concentration (mg/m3)

AL1

1.5

126

76

61

5

125

76

61

10

119

73

60

AL2

1.5

136

80

62

5

132

79

62

10

127

77

61

AL3

1.5

163

91

66

5

159

89

65

10

148

85

64

AL4

1.5

135

80

62

5

132

79

62

10

124

75

61

AL5

1.5

145

84

64

5

137

81

62

10

120

74

60

AL6

1.5

160

90

66

5

134

79

62

10

115

72

60

AL7

1.5

134

79

62

5

125

76

61

10

110

70

59

AL8

1.5

92

63

56

5

91

62

56

10

90

62

56

AL9

1.5

72

55

54

5

72

54

54

10

71

54

54

AL10

1.5

81

58

55

5

81

58

55

10

80

58

55

AL11

1.5

73

55

54

5

73

55

54

10

72

55

54

AL12

1.5

89

62

56

5

89

61

56

10

88

61

56

AL13

1.5

117

73

60

5

116

72

60

10

112

70

59

AL14

1.5

114

71

59

5

112

71

59

10

108

69

59

AL15

1.5

102

67

58

5

101

66

58

10

96

64

57

AL16

1.5

94

63

57

5

93

63

57

10

91

62

56

AL17

1.5

83

59

55

5

83

59

55

10

81

58

55

AL18

1.5

230

118

75

5

212

111

73

10

166

92

67

AL19

1.5

129

77

62

5

127

77

61

10

121

74

61

AL20

1.5

142

83

63

5

139

81

63

10

132

79

62

AL21

1.5

145

84

64

5

118

73

60

10

96

64

57

Notes:

(1) Value in bold type indicates that the NO2 concentration exceeds the HKAQO.

(2) Background NO2 concentration of 43 mg/m3 and RSP concentration of 50 mg/m3 are included.

 

Table 8.7          Predicted SO2 concentrations at Representative ASRs for Future Scenario

 

ASR ID

Assessment Height (mAG)

Hourly Averaged SO2 concentration (mg/m3)

AL14

1.5

104

5

105

10

107

20

114

40

160

60

332

70

440

80

386

100

217

AL15

1.5

134

5

134

10

135

20

135

40

173

60

204

70

204

80

191

100

129

Note: Background concentration of SO2 concentration = 15 mg/m3 is included.

8.41            As indicated in Tables 8.5 & 8.6, the NO2 & RSP concentrations at all representative ASRs in the future scenarios (with or without development of the Park) would comply with the AQO limits.  The contour plots for hourly and daily average NO2 and daily average RSP are only provided for the future scenario (Redeveloped Park) and are presented in Figures 8.3 to 8.5.  The contour plots indicated that there would be no exceedance of either hourly or daily AQO at any of the ASRs within the Study Area (i.e. 500 m from the Project boundary).  There would not be any AQO exceedance within the boundary of the planned school, AL18 (St. Paul’s Co-educational Primary School).  The ASRs (temporary structures) located in the vicinity of the Aberdeen Tunnel portal outside the Study Area have also been considered in the assessment.  Assessment results indicated that these ASRs in the area surrounding the portal would also comply with the AQOs.

8.42            As shown in Table 8.7, the worst hit SO2 impact at the ASRs within the Ocean Park would occur at 70m above ground level.  The contour plot for hourly SO2 concentrations at the worst hit level is illustrated in Figure 8.6.  Results indicated that the predicted SO2 concentration at the ASRs within Ocean Park in future would comply with the AQO limits. 


Mitigation of Adverse Environmental Impacts

Construction Phase

Good Site Practice

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

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

§     Use of frequent watering for particularly dusty construction areas, temporary stockpiles and areas close to ASRs.

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

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

§     Restricting heights from which materials are dropped, as far as practicable to minimise the fugitive dust arising from unloading/ loading.

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

§     Use of vehicle wheel and body washing facilities at the exit points of the site.

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

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

§     Dusty activities should be re-scheduled if high-wind conditions are encountered.

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

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

Drilling & Blasting

8.44            The following mitigation measures would be adopted for drilling & blasting activities:

§     Watering on the exposed area after blasting.

§     Use of vacuum extraction drilling methods.

§     Carefully sequenced blasting.

§     Firing of explosive would be carried out in the morning prior to opening of the Park.

Crushing Plant

8.45            The following mitigation measures would be adopted for temporary crusher:

§     Water sprays on the crusher.

§     Fabric filters installed for the crushing plant.

§     When transferring materials from crusher to the conveyors, chutes or dust curtains would be used for controlling dust.

Barging Point & Conveyor Belt System

8.46            To ensure negligible dust emission from the barging point and conveyor belt system, the following measures would be adopted:

§     The conveyors would be placed within a totally enclosed structure (see Figure 3.5 and 3.6).

§     Profiled steel cladding would be provided at two sides of loading point.

§     Dust suppression sprays would be installed and operated in strategic locations at the feeding inlet and outlet.

§     The barging point would be placed within a totally enclosed structure incorporating an enclosed chute for material transfer to the barge.   Flexible curtain would hang on the enclosed chute to prevent dust emission when excavated materials/rocks are transported into the barge.

8.47            Some areas of the Park would remain open for visitors during the construction period.  Therefore, suitable buffer zones from major construction activities should be provided where practical and the works areas should be fenced off with hoarding during the construction phase.   It is recommended to erect hoarding of a height not less than 2.4m from ground level.

Operational Phase

8.48            No adverse air quality impact are expected to arise from the additional traffic induced due to operation of redeveloped Ocean Park, therefore mitigation measures would not be required.    

Evaluation of Residual Impacts

Construction Phase

8.49            With the implementation of the Air Pollution Control (Construction Dust) Regulation and proposed mitigation measures, adverse residual impact is not expected.

Operational Phase

8.50            No adverse residual impact is expected during the operational phase.    

Environmental Monitoring and Audit

Construction Phase

8.51            An Environmental Monitoring and Audit (EM&A) programme is recommended to be established to check compliance with legislative requirements.   All the recommended mitigation measures should be incorporated into the EM&A programme for implementation during construction.  Details are provided in a stand-alone EM&A Manual.

Operational Phase

8.52            The assessment concluded that the project would not result in unacceptable traffic emission impacts, and so no mitigation measures are required.  Hence, there would be no EM&A requirement for the operational phase of the Project.

Conclusion

Construction Phase

8.53            With the implementation of effective dust suppression measures, no adverse construction dust impact would be expected in the vicinity of the project.  Similarly, visitors in the park should not be affected.

Operation Phase

8.54            Cumulative emissions from nearby pollutant sources such as chimneys, and road traffic on nearby roads as well as emissions from the Aberdeen Tunnel were assessed.  The air quality impact due to operation of the future Ocean Park (scenarios for redeveloped Park & Park without development), even assuming a worst case scenario, would be within acceptable limits since all the relevant AQO would likely be achieved.