4.0 AIR QUALITY IMPACT ASSESSMENT

Introduction

4.1 This section evaluates the likely air quality impacts associated with the construction/operation of the proposed concrete batching plant and the concurrent construction works at Telegraph Bay. The key issues will be dust impacts arising from the works and the plant.

Assessment Criteria

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

4.3 The Air Pollution Control Ordinance (APCO) provides the statutory authority for controlling air pollutants from a variety of sources. The ordinance encompasses a number of Air Quality Objectives (AQOs) which stipulate maximum concentrations for a range of pollutants, of which Total Suspended Particulates (TSP) are relevant to this study. The relevant AQOs are listed in Table 4.1.

Table 4.1 Hong Kong Air Quality Objectives

Parameter	Maximum Average Concentration1, µg/m^3
	1-Hour2	24-Hour3	Annual4
TSP	---	260	80

1. Measured at 298 K and 101.325 kPa.

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

3 Not to be exceeded more than once per year.

4. Arithmetic means.

4.4 In addition to the AQOs, a non-statutory 1-hour average criterion for Total Suspended Particulates (TSP) of 500 mg/m³ (at 298 K and 101.325 kPA) is adopted for assessing construction dust impacts (as specified in the EIA-TM).

Description of Surrounding Environment

4.5 Telegraph Bay is located on the western side of Hong Kong Island and is to be developed with residential towers and G/IC facilities which are compatible with existing developments in the area.

4.6 Telegraph Bay occupies a reclaimed bay with high landscape quality comprising wooded valleys slopes, streams and armoured sea frontage. The site consists of two areas. The larger northern section (proposals for 3 housing sites and 1 G/IC sit) is located at the foot of the western slopes of Hong Kong Island, on the reclaimed site of Telegraph Bay. The southern section ( 1 housing site) occupies the prominent spur of headland between Waterfall Bay and Telegraph Bay.

Identification of Air sensitive receivers

4.7 Nearby sensitive receivers for air quality in the vicinity of the Study Area are identified. The selected sensitive receivers are made with reference to the approved EIA Report . Description of the sensitive receivers is provided in Table 4.2. Figure 4.1 shows the location of the selected sensitive receiver for the air quality assessment.

Table 4.2 Locations of the Air Sensitive Receivers

ASR	SR No.	Description	Land Use1	App. distance between the plant and the ASRs (m)
1	SR1	Stanley Ho Sports Centre	Rec	1033
2	SR2	Tam Villa	R	890
3	SR3	HKU Staff Quarters	R	771
4	SR4	42 Sasson Road	R	619
5	SR5	45 Sasson Road	R	530
6	SR6	47 Sasson Road	R	530
7	SR7	50 Sasson Road	R	518
8	SR8	60 Sasson Road	R	458
9	SR9	Magnolia Villas	R	577
10	SR10	Point Breeze	R	518
11	SR11	Carriana Sasson	R	601
12	SR12	Stone Manor	R	676
13	SR13	Provident Villas	R	768
14	SR14	HKU Medical Faculty	S	878
15	SR18	Ebenezer Home for the Blind	S	845
16	SR19	16-18, Baguio Villas	R	310
17	SR21	Pok Fu Lam Training Centre	S	571
18	SR22	Pok Fu Lam Garden	R	658
19	SR23	Wah Fu Estate	R	780
20	SR24	Lui Ming Choi Secondary School	S	726
21	SR25	Precious Blood Primary School	S	798
22	SR26	Tsui Ching Tong School for the Handicap	S	810
23	SR27	Kong Sin Wan Tsuen	R	589
24	SR40	Pui Ying Secondary School	S	774

1. Residential uses (R); School (S); Recreational uses (Rec)

Meteorology

4.8 The potential for the dispersion of air pollution is very much dependent on local factors such as wind speed, wind direction, and atmospheric stability.

4.9 Site specific meteorological data for the Telegraph Bay Area are limited. The study has therefore reviewed the nearest Hong Kong Observatory meteorological station data to gain an overall appreciation of likely meteorological conditions that would prevail at the study area.

4.10 The fugitive emissions will be determined by local prevailing meteorological conditions. An understanding of prevailing wind speed and direction at the study area will help to determine potential air quality concerns.

4.11 Hong Kong’s climate is dominated by two monsoons:

§ The warm rain bearing south easterly summer monsoon; and

§ The cool dry north-easterly winter monsoon

4.12 The frequency of stable atmospheric conditions over Hong Kong is about 10-20% whilst unstable conditions occur about 30-40% of the time.

4.13 The proposed development site at Telegraph Bay lies between the HK Observatory meteorological sites at Green Island and Wong Chuk Hang.

Identification of Air Pollution Sources

Concurrent Construction Activities

4.14 Dust impact will arise from the following concurrent construction activities:

Ÿ Advance Works for Telegraph Bay Development, including earthworks and surcharging on the reclamation area;

Ÿ Main Construction Works for Telegraph Bay Development, including access roadworks, civil works and superstructure construction; and

Ÿ Construction and operation of the Concrete Batching Plant.

4.15 During the construction phase, dust generating construction activities include vehicle movements, site clearance, drilling, ground excavation and material handling. Wheel wash units will be provided at the entrances and exits of the worksite and, with the proper use of these facilities, there will be minimal dust nuisance outside the worksite. However, fugitive dust will arise from the vehicle movements within the worksite.

4.16 The main dust impacts will arise from truck movements along the unpaved haul roads. Secondary impacts will arise through the stockpiling and removal of spoil during the advance works and main construction works period. The amounts of material expected to be handled during the period December 2000 to December 2001 are summarized in Table 4.3

Table 4.3 Spoil Handling During Construction Phases

Construction Activities	Spoil Quantity (m^3)	Estimated Number of Dump Trucks on Haul road
Advance Works Disposal*	330,000	83 veh/hr
Main Construction Works** Road D1 Road D2 Southern Access Road Northern Access Road	22,280 8,700 124,165 9,900	20 veh/hr
Concrete batching Plant		185 trips/day

* As the import from the sand fill and public has been performed before December 2000, the handling due to the import is not taken into account.

** Since the concrete batching plant is situated on the proposed Route 7, the construction of Route 7 will not take place during the operation of the concrete batching plant.

Construction of Batching Plant

4.17 Major construction works are formation of foundation, erection of carbon steel supports, metal works including welding and assembly of fabricated metal sheets. Since the excavation material is small (~1200m³), the amounts of dust that will be generated from such works are relatively minor compared with other concurrent construction works at the Telegraph Bay Reclamation. However, during construction, the requirements of the Air Pollution Control (Construction Dust) Regulation in dust control will be strictly followed.

Operation of the Batching Plant

4.18 During the operation of the proposed batching plant, dust emission sources can be identified in the plant. They involve:

Ÿ Emissions from the dust collectors;

Ÿ Emissions for unloading of materials to receiving hopper;

Ÿ Emissions from aggregate stockpile; and

Ÿ Emissions from paved access road.

Assessment Methodology

Dispersion Modelling

4.19 Dispersion modelling has been undertaken using USEPA approved Fugitive Dust Model (FDM) to assess potential dust impacts arising from construction activities and fugitive dust sources. Surface roughness was taken to be 0.6 metre in the FDM model to represent the terrain in the vicinity of the study area.

4.20 For the purpose of this assessment, it is considered that dust emissions from vehicles moving on unpaved road surfaces would constitute the major dust source for most of the construction sites. There is no site-specific information relating to particle size distribution, and as a result, assumptions were made using the unpaved road emission equation from AP-42 (5th Edition) to provide input for the FDM modelling. Particle size distribution was estimated based on the most appropriate particle size multipliers. For the modelling exercise 9 particle size classes were used in the FDM model. Their averaged diameters are 0-1 µm, 1-2 µm, 2-2.5 µm, 2.5-3 µm, 3-4 µm, 4-5 µm, 5-6 µm, 6-10 µm and 10-30 µm. The percentage in each class was estimated to be 4%, 7%, 4%, 3%, 7%, 5%, 4%, 17% and 49% respectively.

Meteorological Conditions

4.21 According to the Guideline on Choice of Models and Model Parameters, the worst case meteorological data was used for the FDM modelling:

Mixing height : 500m

Stability Class : D

Wind Direction : worst-case wind angle

Surface Roughness : 0.6 m

Height of Emissions : Ground Level

Wind speed at 1, 2 and 4m/s was tested and the worst case is selected.

Background Pollutant Concentrations

4.22 Background pollutant concentrations have been derived from the baseline monitoring result performed in December 1999 in Cyberport. Therefore, the baseline 1-hour TSP and 24-hour TSP are 265 mg/m³ and 59 mg/m³ respectively.

4.23 In the absence of in-situ monitoring data, the annual average TSP concentration has been used as the background concentration for the impact assessment.

Emission Factors

4.24 The particulate emission rates are estimated using the Compilation of Air Pollutant Emission Factors (AP-42), USEPA, 5^th edition, 1995. The emission factors used in the modelling are tabulated in Table 4.4.

Table 4.4 Emission Factors of Dust Generating Activities

Activities	Emission Factor
Truck movements unpaved roads	Appendix 4.1
Handling of spoil (loading/unloading)	Appendix 4.1
Wind erosion	Appendix 4.1
Emissions for unloading of materials to receiving hopper	AP 42 Section 11.19.2, Table11.19.2-1
Emissions from aggregate stockpile	AP 42 Section 13.2.4
Paved roads	AP 42 Section 13.2.1

Impact Assessment

4.25 During the construction of the Concrete Batching Plant, the requirement of the Air Pollution Control (Construction Dust) will be followed. As the construction period of the plant is short (< 120days) and the amount of excavated material is small (~1200m³), the impact due to the construction phase of the concrete batching plant is smaller than that during the operation stage. Therefore, the operation phase of the concrete batching plant is presented in this report.

4.26 In the schematic process, there will be totally eleven emission points. Detail calculations of the source strengths of the identified emission points in plant are given in Appendix 4.2.

4.27 The concrete recycling machine is used to recycle wet concrete waste, which will not generate dust problem.

4.28 Mitigation measures which have been assumed in the concrete batching plant assessment are summarized in Table 4.5.

Table 4.5 Mitigation Measures incorported on the Proposed Concrete Batching Plant

Item/ Process	Description	Mitigation Measures
Unloading of Sand And Aggregates	a. Unloading of Sand and Aggregates from Barge to aggregate Receiving Hopper at Seafront	· Water spray installed on barge for wetting the sand and aggregates1 · Conveyor barge designed for unloading aggregate3 · Fully enclosed conveyor used to unload the material to the aggregate receiving hopper1 · Aggregate receiving hopper installed with 3 sides and water spray1
	b. Unloading of wetted Sand and Aggregates from Aggregate Receiving Hopper to Tipper truck	· The wetted sand and aggregates are loaded into the tipper truck in enclosed loadout section1
Storage of Sand and Aggregates	Storage of Sand and Aggregates in Ground Storage Yards and Aggregate Storage Bins. Storage of Sand and Aggregates in Fully Enclosed Aggregate Overhead Storage Bins	· The storage yards are installed with 3 sides enclosure and roof, curtain at entrance1 · Water spray is installed in storage yard for wetting the sand and aggregates1 · Aggregate Storage Bins and Aggregate Overhead Storage Bins are fully enclosed1
Transfer of Sand And Aggregates	a. Transfer of sand and Aggregates from Loadout Section to Storage Yards by tipper truck	· The tipper trucks with wetted sand and aggregates are covered with plastic canvas2 · The aggregate materials are unloaded into storage yards, which have 3 sides and roof enclosed and curtain at entrance and water spray1
	b. Transfer of Sand and Aggregates from Storage Yards to Aggregate Receiving Hoppers by loader	· The sand and aggregates are wetted before transferring to aggregate receiving hopper1 · Aggregate receiving hopper installed with 3 sides and roof and water spray1
	c. Transfer of Sand and Aggregates from Seafront Aggregate Receiving Hopper to Aggregate Storage Bins OR from Ground Aggregate Receiving Hopper or from Aggregate Storage Bins to Overhead Aggregates Storage Bins	· The sand and aggregates are transferred by fully enclosed conveyors1 · Aggregate conveyor and Transfer Points are fully enclosed1 · The sand and aggregates are unloaded into fully enclosed overhead storage bins1
Batching of Sand And Aggregates	a. Weighing and Batching of Sand and Aggregate by Aggregate Weigh Hopper	· The sand and aggregates are transferred and weighed within an enclosed structure1
Unloading of Cementitious Material	a. Transfer of Cementitous Material from Cement Barge to Cement Tankers or directly to Plant Silos	· All cementitious materials are transferred within a fully enclosed piping system1,2 · The cement blower of barge is enclosed1,2 · The cement tanker and silos are fully enclosed systems1,2 · Dust-laden air is filtered through bag filter and vented to the dust collectors1,2
Transferring of Cementitious Material	a. Transferring of Cementitious Material from cement tanker to Silos	· The silos are fully enclosed1,2 · Dust-laden air is filtered through bag filter and vented tot he dust collectors1,2 · The level alarms are installed for all silos to prevent overfilling1,2 · Cement Tanker will transfer the materials within an enclosure1,2
Batching of Cementitious Material	a. Weighing and batching of Cementitious Material by Cement Weigh Hoppers	· The weigh hopper is fully enclosed1,2 · Dust-laden air from the cementitious weigh hoppers is filtered through bag filter and vented to the dust collector1,2 · Cementitious transfer using fully enclosed pipes and screw conveyors1,2
Mixing of Sand, Aggregates and Cementitious Material	a. Mixing of Batched Sand, Aggregates and Cementitious Material in the Concrete Mixer	· The mixer is fully enclosed1,2 · Dust-laden air in the mixer is filtered though bag filter and vented to the dust collector1,2
Truck Loading	a. Loading of mixed concrete into the trucks	· All mixing & loading conduct in fully enclosed area1 · Truck loaded with concrete in “Wet” form1,2
Plant Yard	a. The Concrete Batching Plant Area	· Floor to be concrete paved1,2 · Pavement to be kept moist with water1,2
Concrete trucks	a. Concrete Delivery Mixer Trucks within Cyber Port Site	· Well maintained trucks3 · Clean trucks regularly1 · Trucks comply with APCO regulations2
Plant Equipment	a. Facilities and equipment operates within the batching plant for handling materials and producing concrete	· Perform regular maintenance works for plant equipment1,3 · Maintain all environmental control facilities in operating condition3

1. Recommended by the Best Practicable Means Requirement for Cement Works (Concrete Batching Plant)

2. Recommended by the Air Pollution Contral (Construction Dust) Regulation in Dust Control

3. Good Site Management Practices

4.29 Sample of computer output is shown in Appendix 4.3.

4.30 Results in Tables 4.6 and 4.7 demonstrate that the TSP concentrations arising from the batching plant at the representative ASRs are well below the AQOs. Therefore, there is no air quality impact arising from the plant on the nearby ASRs.

Table 4.6 Predicted TSP Concentration Levels at Representative Air Sensitive Receivers without mitigation at 1.5m height

		TSP Concentration (mgm^-3)
		Concrete^1		Others^2		Background		Overall
		1-hr	24-hr	1-hr	24-hr	1-hr	24-hr	1-hr	24-hr
1	SR1	8	4	432	216	265	59	705	279
2	SR2	11	5	550	275	265	59	826	339
3	SR3	13	7	685	342	265	59	963	408
4	SR4	19	9	957	479	265	59	1241	547
5	SR5	24	12	1108	554	265	59	1397	625
6	SR6	24	12	1162	581	265	59	1451	652
7	SR7	26	13	1296	648	265	59	1587	720
8	SR8	30	15	1453	726	265	59	1748	800
9	SR9	22	11	1091	545	265	59	1378	615
10	SR10	26	13	1341	670	265	59	1632	742
11	SR11	20	10	961	481	265	59	1246	550
12	SR12	16	8	772	386	265	59	1053	453
13	SR13	13	7	671	336	265	59	949	402
14	SR14	11	5	540	270	265	59	816	334
15	SR18	11	6	476	238	265	59	752	303
16	SR19	57	29	1078	539	265	59	1400	627
17	SR21	23	12	543	271	265	59	831	342
18	SR22	18	9	529	265	265	59	812	333
19	SR23	13	7	739	369	265	59	1017	435
20	SR24	15	8	1010	505	265	59	1290	572
21	SR25	13	7	788	394	265	59	1066	460
22	SR26	13	6	763	382	265	59	1041	447
23	SR27	20	10	1011	505	265	59	1296	574
24	SR40	14	7	791	395	265	59	1070	461

¹Concrete batching plant, with dust suppression measures

²Concurrent construction works at the site

Bolded figure indicate the exceedance of the 1-hr or 24-hr TSP criteria

Table 4.7 Predicted TSP Concentration Levels at Representative Air Sensitive Receivers without mitigation at 10m height

		TSP Concentration (mgm^-3)
		Concrete^1		Others^2		Back-		Overall
		1-hr	24-hr	1-hr	24-hr	ground		1-hr	24-hr
1	SR1	9	4	446	223	265	59	720	286
2	SR2	11	5	560	280	265	59	836	344
3	SR3	13	7	689	344	265	59	967	410
4	SR4	19	9	936	468	265	59	1220	536
5	SR5	24	12	1051	526	265	59	1340	597
6	SR6	24	12	1103	552	265	59	1392	623
7	SR7	25	13	1217	609	265	59	1507	681
8	SR8	29	15	1323	662	265	59	1617	736
9	SR9	21	11	1053	526	265	59	1339	596
10	SR10	25	13	1260	630	265	59	1550	702
11	SR11	20	10	933	467	265	59	1218	536
12	SR12	16	8	764	382	265	59	1045	449
13	SR13	13	7	672	336	265	59	950	402
14	SR14	11	5	549	274	265	59	825	338
15	SR18	11	6	479	240	265	59	755	305
16	SR19	53	26	952	476	265	59	1270	561
17	SR21	23	12	521	260	265	59	809	331
18	SR22	18	9	523	262	265	59	806	330
19	SR23	14	7	735	368	265	59	1014	434
20	SR24	15	8	896	448	265	59	1176	515
21	SR25	13	7	765	383	265	59	1043	449
22	SR26	13	6	734	367	265	59	1012	432
23	SR27	20	10	948	474	265	59	1233	543
24	SR40	14	7	785	392	265	59	1064	458

¹Concrete batching plant, with dust suppression measures

²Concurrent construction works at the site

Bolded figure indicate the exceedance of the 1-hr or 24-hr TSP criteria

4.31 Contours of the cumulative 1-hour and 24-hour average TSP concentrations at the levels of 1.5m and 10m above ground are presented in Figures 4.2 and 4.3, showing exceedance of the TSP criteria at sensitive receiver locations.

4.32 As shown in Tables 4.6 and 4.7, the cumulative TSP concentrations are expected to exceed the TSP criteria at all Air sensitive Receivers. In order to comply with the TSP criteria, the following mitigation measures are proposedhave incorporated for the concurrent construction works at Telegraph Bay:

Ÿ Twice daily watering (with complete coverage) of the whole area. Through the implementation of this mitigation measure, dust emissions from materials handling can be reduced by 50%, according to AP-42.

Ÿ Speed control of dump truck in site area can reduce dust generation by 50%, according to AP-42.

Ÿ A watering program of once every 2 hours in normal weather conditions, and hourly in dry/windy condition on all haul roads can reduce dust emission by 97%, according to the Scheme 1 of the EIA report for the Infrastructural Works for the Proposed Development at Telegraph Bay.

4.33 The mitigated cumulative 1-hour and 24-hour average TSP concentrations are shown in Tables 4.8 and 4.9. The contours of the TSP concentration are shown in Figures 4.4 and 4.5.

Table 4.8 Predicted TSP Concentration Levels at Representsative Air Sensitive Receivers with mitigation at 1.5m height

		TSP Concentration (mgm^-3)
		Concrete^1		Others^2		Background		Overall
		1-hr	24-hr	1-hr	24-hr	1-hr	24-hr	1-hr	24-hr
1	SR1	8	4	16	8	265	59	289	71
2	SR2	11	5	20	10	265	59	296	74
3	SR3	13	7	25	12	265	59	303	78
4	SR4	19	9	34	17	265	59	318	85
5	SR5	24	12	41	21	265	59	330	92
6	SR6	24	12	42	21	265	59	331	92
7	SR7	26	13	45	23	265	59	336	95
8	SR8	30	15	51	25	265	59	346	99
9	SR9	22	11	39	19	265	59	326	89
10	SR10	26	13	47	24	265	59	338	96
11	SR11	20	10	35	18	265	59	320	87
12	SR12	16	8	28	14	265	59	309	81
13	SR13	13	7	24	12	265	59	302	78
14	SR14	11	5	20	10	265	59	296	74
15	SR18	11	6	18	9	265	59	294	74
16	SR19	57	29	40	20	265	59	362	108
17	SR21	23	12	20	10	265	59	308	81
18	SR22	18	9	20	10	265	59	303	78
19	SR23	13	7	26	13	265	59	304	79
20	SR24	15	8	37	18	265	59	317	85
21	SR25	13	7	29	14	265	59	307	80
22	SR26	13	6	28	14	265	59	306	79
23	SR27	20	10	38	19	265	59	323	88
24	SR40	14	7	28	14	265	59	307	80

¹Concrete batching plant, with dust suppression measures

²Concurrent construction works at the site, with dust suppression measures

Table 4.9 Predicted TSP Concentration Levels at the Selected Air Sensitive Receivers with mitigation at 10m height

		TSP Concentration (mgm^-3)
		Concrete^1		Others^2		Background			Overall
		1-hr	24-hr	1-hr	24-hr	1-hr	24-hr		1-hr	24-hr
1	SR1	8	4	16	8	265		59	289	71
2	SR2	11	5	20	10	265		59	296	74
3	SR3	13	7	25	12	265		59	303	78
4	SR4	19	9	34	17	265		59	318	85
5	SR5	24	12	39	20	265		59	328	91
6	SR6	24	12	40	20	265		59	329	91
7	SR7	26	13	43	21	265		59	334	93
8	SR8	30	15	46	23	265		59	341	97
9	SR9	22	11	37	19	265		59	324	89
10	SR10	26	13	44	22	265		59	335	94
11	SR11	20	10	34	17	265		59	319	86
12	SR12	16	8	28	14	265		59	309	81
13	SR13	13	7	24	12	265		59	302	78
14	SR14	11	5	20	10	265		59	296	74
15	SR18	11	6	18	9	265		59	294	74
16	SR19	57	29	36	18	265		59	358	106
17	SR21	23	12	19	10	265		59	307	81
18	SR22	18	9	19	10	265		59	302	78
19	SR23	13	7	26	13	265		59	304	79
20	SR24	15	8	32	16	265		59	312	83
21	SR25	13	7	28	14	265		59	306	80
22	SR26	13	6	27	13	265		59	305	78
23	SR27	20	10	35	18	265		59	320	87
24	SR40	14	7	28	14	265		59	307	80

¹Concrete batching plant, with dust suppression measures

²Concurrent construction works at the site, with dust suppression measures

4.34 From the results, it was noted that with the implementation of the dust suppression measures on the concurrent construction works at Telegraph Bay, no adverse cumulative dust impact is expected at all ASRs.

Conclusions

4.35 The construction works of the concrete batching plant are much smaller than the concurrent construction works of the Telegraph Bay Reclamation. Therefore, the dust impact during construction phase of the concrete batching plant is insignificant. However, during the construction of concrete batching plant, the Air Pollution Control (Construction Dust) Regulation would be strictly followed.

4.36 During operation phase, the concrete batching plant should strictly follow the requirements stipulated in the Best Practicable Means Requirement for Cement Works (Concrete Batching Plant) and the Air Pollution Control (Construction Dust) for dust control. Besides, the following practices will also be incorporated:

· Dust collectors will be sized to exceed the requirement of the Specified Processes Regulation.

· For Stage 1, the cement tankers will be working inside enclosure with cladding to reduce air quality impactnoise.

· For stage 2, cement will be transferred directly from barges to the plant. There is no need for cement tankers for intermediate transfer.

4.37 With the implementation of the mitigation measures at the concrete batching plant and the concurrent construction site at the Telegraph Bay, the predicted cumulative 1-hour and 24 hour TSP concentration are expected to comply with the Air Quality Objectives.