3 sAIR QUALITY Impact

3.1 Introduction

3.1.1 This section presents an air quality impact assessment during dredging works for proposed cruise terminal at Kai Tak. Potential air quality impact associated with the Project has been identified and assessed. Appropriate mitigation measures are proposed to alleviate any adverse air quality / odour impacts if necessary.

3.2 Environmental Legislation, Policies, Plans, Standards and Criteria

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

Air Quality Objectives and EIAO-TM

3.2.2 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 3.1.

^Table³^.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	-	-	-

Notes:

(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.

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

3.2.4 In accordance with the EIAO-TM, odour impact predicted at an air sensitive receiver should meet 5 odour units based on an averaging time of 5 seconds.

3.3 Description of the Environment

3.3.1 The Project area is located near the southern tip of the former Kai Tak Airport runway. There is no air quality monitoring station located in the study area. EPD’s Sham Shui Po and Kwun Tong air quality monitoring stations are the nearest stations to the Project site. Table 3.2 summarizes the annual average concentrations of the air pollutants recorded at these two monitoring stations in Year 2005.

^Table³^{.2 Annual Average Concentrations of Pollutants
in}^{Year 2005 at
EPD’s Sham Shui Po and Kwun Tong Air Quality Monitoring Station}^s

Pollutant	Annual Average AQO (mg m^-3)	Year 2005 Annual Average Concentration (mg m^-3)
Pollutant	Annual Average AQO (mg m^-3)	Sham Shui Po station	Kwun Tong station
TSP	80	83	81
RSP	55	56	56
NO₂	80	65	58
SO₂	80	24	18

3.4 Air Quality Sensitive Receivers

3.4.1 In accordance with the Annex 12 of the EIAO-TM, any domestic premises, hotel, hostel, hospital, clinic, nursery, school, educational institution, office, factory, shop, shopping centre, place of public worship, library, court of law, sports stadium or performing arts centre are considered to be an air sensitive receiver (ASR). Any other place with which, in terms of duration or number of people affected, has a similar sensitivity to the air pollutants as the aforelisted places are also considered to be an ASR, for example, playground, sitting area of parks / promenade.

3.4.2 The Project would be conducted in two stages namely Stage 1 with dredging activities for Phase I Berth and seawall reconstruction (later half of Year 2008 – end Year 2011) and Stage 2 with dredging activities for berth 2 (Year 2013 – Year 2014). The programme for Stage 2 dredging is indicative only and the actual programme would depend on the commissioning programme for the second berth. In accordance with Section 3.4.5.2 of the EIA Study Brief No. ESB-159/2006, the air quality impact assessment area is defined by a distance of 500m expanded from the boundary of the Project. The study areas of air quality impact assessment for the Stage 1 works and Stage 2 works are shown in Figure 3.1 and Figure 3.2, respectively.

3.4.3 Referring to the study area of the Stage 1 works, no existing ASRs are identified. The dredging activities under the Stage 1 works would be completed before Year 2012. Within 500m from the dredging area of the Stage 1 works, based on the latest available information, there are no planned ASRs occupied at the former Kai Tak Airport runway before Year 2012.

3.4.4 The dredging activities under the Stage 2 works (for the second berth) are assumed to commence in Year 2013 or later. As there is no available information on the commissioning year of the planned developments at the former Kai Tak Airport runway after Year 2013, as a conservative assumption for the purpose of this assessment, the planned developments at the former Kai Tak Airport runway within 500m of the Stage 2 dredging area boundary are assumed to be occupied after Year 2013. The planned Runway Park, the two planned residential R3 sites and the planned hotel which are located nearest to the Stage 2 dredging area are considered to be the worst-affected and thus representative ASRs in this assessment during the period of the Stage 2 works. A landscaped deck above the cruise terminal development will also be considered as representative ASRs in the assessment.

3.4.5 The identified representative ASRs for the Stage 2 dredging are listed in Table 3.3 and the corresponding locations are shown in Figure 3.2.

^Table³^{.3 Details of Representative Air Sensitive
Receivers for the Stage 2 Dredging}

ASR	Description	Use	Maximum Height (mPD)	Distance from Stage 2 Work Boundary (m)
A1	Residential Development (R3 site)	Residential	45	230
A2	Residential Development (R3 site)	Residential	55	280
A3	Planned Hotel	Commercial	100	200
A4	Landscape Deck at Cruise Terminal	Open space	35	85
A5	Planned Runway Park	Open space	5	440

3.5 Identification, Prediction and Evaluation of Environmental Impacts

Construction Dust

3.5.1 The construction activities under the Project would be dredging activities which are mostly marine based and not dusty activities. Marine sediment will be dredged and disposed of at designated marine disposal sites by barge. The moisture content of dredged materials is very high and negligible fugitive dust emissions are therefore anticipated during the construction period.

Odour Impact from Capital Dredging

3.5.2 Dredging would be required in the Harbour fronting the proposed cruise terminal to provide the necessary manoeuvring basin. Marine site investigation and laboratory testing have recently been carried out to determine the contamination level of the sediments within the proposed dredging area for the cruise terminal. The sediment sampling proposal for the marine site investigation and laboratory testing was prepared in accordance with the ETWB TCW No. 34/2002 Management of Dredge/Excavated Sediment and was accepted by EPD under the EIA Study Brief for the feasibility study of the Kai Tak Development and the EIA Study Brief No. ESB-159/2006 for Dredging Works for Proposed Cruise Terminal at Kai Tak.

3.5.3 The marine site investigation was completed in two phases. The first phase of the marine site investigation was commenced on 15 January 2007 and was completed on 23 January 2007 and comprised 30 sampling stations (stations A01-A30) (refer to Figure 6.1). The second phase of the marine site investigation was commenced on 23 February 2007 and was completed on 10 March 2007 and comprised 41 sampling stations (stations B01-B41) (refer to Figure 6.1). The marine site investigation comprised grab sampling and vibrocoring to obtain sediment samples for chemical testing.

3.5.4 The levels of acid volatile sulphide (AVS) were measured for the sediment samples collected under the marine site investigation to assess the potential odour impact from the dredged sediment. In general, high AVS concentrations in sediment indicate that odorous hydrogen sulphide gas is likely to be generated from the sediment. Based on the laboratory analysis results, the AVS levels measured in all the collected sediment samples were below the detection limit of 1 mg/kg.

3.5.5 Bioremediation was previously undertaken at Shing Mun River and Sam Ka Tsuen Typhoon Shelter to eliminate the odour generating potential of the sediment. Percentage of AVS removal was taken as the primary acceptance criteria of the odour remediation works. The measured AVS levels of the sediments collected at Sam Ka Tsuen Typhoon Shelter were ranged from 50 – 500 mg/kg whereas the measured AVS levels of the sediments collected at Shing Mun River were ranged from 90 – 100 mg/kg ^([1]). These sediments are considered to have been remediated to a level with minimum odour impact to the surrounding environment. Based on the results of marine site investigation, the AVS levels of the sediments collected from the dredging area of the proposed cruise terminal were all below the detection limit of 1 mg/kg, which are far below the AVS levels of the remediated sediments at Sam Ka Tsuen Typhoon Shelter and Shing Mun River. Therefore, it is expected that the potential odour emissions from the sediments within the dredging area of the proposed cruise terminal would be minimal and adverse odour impact from the dredging activities in the Stage 1 and 2 areas would not be anticipated. Adverse odour impacts within the study areas of both Stage 1 and Stage 2 works areas are not anticipated disregards whether ASRs are planned in the study areas in the future.

Odour Impact from Maintenance Dredging

3.5.6 Maintenance dredging would be carried out once every 5 to 10 years. The volume of sediment to be dredged during maintenance dredging would be significantly lower than the volume of capital dredging during the construction phase. The period of maintenance dredging would also be shorter than that during capital dredging. Besides, given the continual improvement of sewage collection and treatment in Hong Kong, it is not expected that the sediment quality in the Victoria Harbour would deteriorate in the future. Thus, similar to the above assessment on capital dredging, adverse odour impacts on ASRs due to maintenance dredging are not expected.

3.6 Mitigation of Environmental Impacts

Construction Dust

3.6.1 Negligible dust impacts would be expected from dredging activities. In order to further ensure compliance with the AQOs at the ASRs, requirements of the Air Pollution Control (Construction Dust) Regulation, where relevant, shall be adhered to during the construction period.

Odour Impact from Capital Dredging and Maintenance Dredging

3.6.2 As discussed above, adverse odour impacts during the dredging operation would not be expected. In order to minimize the potential odour emissions, if any, the dredged sediment placed on barge should be properly covered as far as practicable to minimise the exposed area and hence the potential odour emissions during the transportation of the dredged sediment.

3.7 Residual Environmental Impacts

3.7.1 No residual air quality / odour impact would be expected during the course of this Project with the effective implementation of proposed dust and odour mitigation measures.

3.8 Environmental Monitoring and Audit

3.8.1 Air quality / odour monitoring is not required. A regular site audit (weekly audit) will be conducted to ensure compliance of the relevant requirements of the Air Pollution Control (Construction Dust) Regulation and the implementation of the proposed odour mitigation measure.

3.9 Summary

3.9.1 Dredging activities are marine based activities and negligible dust impacts on nearby ASRs would be expected. Referring to the marine site investigation results, the AVS levels measured in all the sediment samples collected from the dredging area of the proposed cruise terminal were below the detection limit of 1 mg/kg. In general, high AVS concentrations in sediment indicate that odorous hydrogen sulphide gas is likely to be generated from the sediment. These AVS levels are far below the AVS levels of the odour remediated sediments collected from Shing Mun River and Sam Ka Tsuen Typhoon Shelter. Therefore, it is expected that the potential odour emissions from the sediments within the dredging area of the proposed cruise terminal would be minimal and adverse odour impact from the dredging activities in the Stage 1 and 2 areas would not be anticipated. Adverse odour impacts during the capital dredging are therefore not expected. Maintenance dredging would be carried out once every 5 to 10 years and adverse odour impacts at ASRs are also not expected.

^([1]) Agreement No. CE 4/2004 (TP) South East Kowloon Development Comprehensive Planning and Engineering Review Stage 1: Planning Review, Situation Report on Odour Issue of Kai Tak Development, November 2006.