Contents

Page

5 WATER QUALITY 1

5.1 Legislation, Standards and Guidelines 1

5.2 Baseline Conditions 9

5.3 Indication Point and Methodology of Quantitative Modelling 33

5.4 Construction Phase Assessment ¡V Land-based Works 42

5.5 Construction Phase Assessment ¡V Marine-based Works 49

5.6 Operational Phase Assessment 97

5.7 Conclusion 118

References

Tables

Figures

Figure 5.1 Locations of Water Sensitive Receivers

Drawings

Pictures

Photographs

Attachments

Appendices

Appendix 5.1a Location of Water Control Zones

Appendix 5.1b Location of HKIA Non-Statutory Water Quality Monitoring Stations

Appendix 5.2a Grid Properties

Appendix 5.2b Validation Data of Refined Model

Appendix 5.3 Results of Pore Water Test

Appendix 5.4a Construction Methodology

Appendix 5.4b Water Quality Modeling Results (Construction Phase)

Appendix 5.5 Calculation of Pollution Inventory due to Project

Appendix 5.6 Hydrodynamic Modeling Results (Operational Phase)

Appendix 5.7 Water Quality Modeling Results (Operational Phase)

Appendix 5.8 Sustainable Urban Drainage Systems and Polder Scheme

5 WATER QUALITY

5.1 Legislation, Standards and Guidelines

5.1.1 Legislation and Guidelines to the Surrounding Waterbodies

Environmental Impact Assessment Ordinance (EIAO) (Cap. 499)

5.1.1.1 EIAO (Cap. 499) provides the major statutory framework for the environmental impact assessment in Hong Kong. Under Section 16 of the EIAO, EPD issued the Technical Memorandum on Environmental Impact Assessment Process (TM-EIAO) which specifies the assessment methods and criteria for the EIA. Annexes 6 and 14 of the TM-EIAO stipulate the ¡§Criteria for Evaluating Water Pollution¡¨ and ¡§Guidelines for the Assessment of Water Pollution¡¨ respectively.

Water Pollution Control Ordinance (Cap. 358)

5.1.1.2 WPCO (Cap 358) provides the major statutory framework for the protection and control of water quality in Hong Kong. According to the Ordinance and its subsidiary legislation, the entire Hong Kong waters are divided into ten Water Control Zones (WCZs) and four supplementary WCZs. Each WCZ has a designated set of statutory Water Quality Objectives (WQOs). The WQOs set limits for different parameters that should be achieved in order to protect specific beneficial uses and conservation goals of each of the zones. The study area is situated within the Northern WCZ and close to Western Buffer WCZ, which are identified with the following beneficial uses:

¡P Nature reserves and Site of Special Scientific Interest;

¡P Maintenance of natural ecosystems and wildlife;

¡P Production of fish, crustaceans and shellfish for human consumption;

¡P Bathing, diving and primary contact recreation;

¡P Boating, fishing and secondary contact recreation;

¡P Aesthetic enjoyment;

¡P Industrial and domestic water supply;

¡P Supply of flushing water;

¡P Navigation and shipping;

¡P Typhoon shelter;

¡P Reception and dilution of effluents.

5.1.1.3 The water quality objectives for the North Western WCZ, North Western Supplementary WCZ and Western Buffer WCZ are summarized in Table 5.1a, Table 5.1b and Table 5.1c. The location of North Western WCZ, North Western Supplementary WCZ and Western Buffer WCZ are presented in Appendix 5.1a.

Table 5.1a WQOs of North Western WCZ

Water Quality Objectives

Aesthetic Appearance

• There should be no objectionable odours or discolouration of the water;

• Tarry residues, floating wood, articles made of glass, plastic, rubber or any other substances should be absent;

• Mineral oil should not be visible on the surface;

• There should be no recognisable sewage derived debris; and

• Floating, submerged and semi-submerged objects of a size likely to interfere with the free movement of vessels, or cause damage to vessels, should be absent.

• Waste discharges should not cause the water to contain substances which settle to form objectionable deposits.

Bacteria

• The levels of E coli should not exceed 180 counts per 100ml at bathing beaches, calculated as the geometric mean of all samples collected from March to October inclusive. Samples have to be taken at least 3 times a month at intervals of between 3 and 14 days;

• The levels of E coli should not exceed 610 counts per 100ml at secondary contact recreation sub-zones, calculated as the geometric annual mean; and

• Waste discharges shall not cause a risk to any beneficial use of the aquatic environment.

Dissolved Oxygen

• The depth averaged concentration of dissolved oxygen should not fall below 4 mg/l for 90% of the sampling occasions during the whole year; and

• The concentration of dissolved oxygen should not be less than 2 mg/l within 2m of the seabed for 90% of the sampling occasions during the whole year.

pH

• The pH of the water should be within the range 6.5-8.5 units; and

• Human activity should not cause the natural pH range to be extended by more than 0.2 units.

Temperature

• Waste discharges shall not cause the natural daily temperature range to change by more than 2.0¢XC.

Salinity

• Waste Discharges shall not cause the natural ambient salinity to change by more than 10%.

Suspended Solids

• Human activity should neither cause the natural ambient level to be raised by more than 30% nor give rise to accumulation of suspended solids which may adversely affect aquatic communities.

Ammonia

• The un-ionised ammoniacal nitrogen level should not be more than 0.021 mg/l calculated as the annual average (arithmetic mean).

Nutrients

• Nutrients should not be present in quantities sufficient to cause excessive or nuisance growth of algae or other aquatic plants; and

• Without limiting the generality of the above point, the level of inorganic nitrogen should not exceed 0.5mg/l in marine waters except Castle Peak sub-zone and 0.3mg/l within Castle Peak sub-zone, expressed as the annual water column average.

Toxins

• Waste discharges shall not cause the toxins in water to attain such a level as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or other aquatic organisms, with due regard to biologically cumulative effects in food chains and to interactions of toxic substances with each other.

Table 5.1b WQOs of North Western Supplementary WCZ

Water Quality Objectives

Aesthetic Appearance

• There should be no objectionable odours or discolouration of the water;

• Tarry residues, floating wood, articles made of glass, plastic, rubber or any other substances should be absent;

• Mineral oil should not be visible on the surface;

• There should be no recognisable sewage derived debris; and

• Floating, submerged and semi-submerged objects of a size likely to interfere with the free movement of vessels, or cause damage to vessels, should be absent.

• Waste discharges should not cause the water to contain substances which settle to form objectionable deposits.

Bacteria

• The level of Escherichia coli should not exceed 610 per 100 mL, calculated as the geometric mean of all samples collected in a calendar year.

Dissolved Oxygen

• The depth averaged concentration of dissolved oxygen should not fall below 4 mg/l for 90% of the sampling occasions during the whole year; and

• The concentration of dissolved oxygen should not be less than 2 mg/l within 2m of the seabed for 90% of the sampling occasions during the whole year.

pH

• The pH of the water should be within the range 6.5-8.5 units; and

• Human activity should not cause the natural pH range to be extended by more than 0.2 units.

Temperature

• Waste discharges shall not cause the natural daily temperature range to change by more than 2.0¢XC.

Salinity

• Waste Discharges shall not cause the natural ambient salinity to change by more than 10%.

Suspended Solids

• Human activity should neither cause the natural ambient level to be raised by more than 30% nor give rise to accumulation of suspended solids which may adversely affect aquatic communities.

Ammonia

• The un-ionised ammoniacal nitrogen level should not be more than 0.021 mg/l calculated as the annual average (arithmetic mean).

Nutrients

• Nutrients should not be present in quantities sufficient to cause excessive or nuisance growth of algae or other aquatic plants; and

• Without limiting the generality of the above point, the level of inorganic nitrogen should not exceed 0.5mg/l expressed as the annual water column average.

Toxins

• Waste discharges shall not cause the toxins in water to attain such a level as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or other aquatic organisms, with due regard to biologically cumulative effects in food chains and to interactions of toxic substances with each other.

Table 5.1c WQOs of Western Buffer WCZ

Water Quality Objectives

Aesthetic Appearance

• There should be no objectionable odours or discolouration of the water;

• Tarry residues, floating wood, articles made of glass, plastic, rubber or any other substances should be absent;

• Mineral oil should not be visible on the surface;

• There should be no recognisable sewage derived debris; and

• Floating, submerged and semi-submerged objects of a size likely to interfere with the free movement of vessels, or cause damage to vessels, should be absent.

• Waste discharges should not cause the water to contain substances which settle to form objectionable deposits.

Bacteria

• The level of Escherichia coli should not exceed 610 per 100 mL in Secondary Contact Recreation Subzones and Fish Culture Subzones, calculated as the geometric mean of all samples collected in a calendar year.

• The level of Escherichia coli should not exceed 180 per 100 mL in Recreation Subzones, calculated as the geometric mean of all samples collected from March to October inclusive in 1 calendar year. Samples should be taken at least 3 times in 1 calendar month at intervals of between 3 and 14 days.

• The level of Escherichia coli should be less than 1 per 100 mL in Water Gathering Ground Subzones, calculated as the geometric mean of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days.

Dissolved Oxygen

• For Marine waters excepting Fish Culture Subzones, the level of dissolved oxygen should not fall below 4 mg per litre for 90% of the sampling occasions during the whole year; values should be calculated as water column average (arithmetic mean of at least 3 measurements at 1 m below surface, mid-depth and 1 m above seabed). In addition, the concentration of dissolved oxygen should not be less than 2 mg per litre within 2 m of the seabed for 90% of the sampling occasions during the whole year.

• For Fish Culture Subzones, the level of dissolved oxygen should not be less than 5 mg per litre for 90% of the sampling occasions during the years; values should be calculated as water column average (arithmetic mean of at least 3 measurements at 1 m below surface, mid-depth and 1 m above seabed). In addition, the concentration of dissolved oxygen should not be less than 2 mg per litre within 2 m of the seabed for 90% of the sampling occasions during the whole year.

pH

• For Marine waters, the pH of the water should be within the range 6.5-8.5 units;

• For Water Gathering Ground Subzones, human activity should not cause the natural pH range to be extended by more than 0.2 units.

Temperature

• Waste discharges shall not cause the natural daily temperature range to change by more than 2.0¢XC.

Salinity

• Waste Discharges shall not cause the natural ambient salinity to change by more than 10%.

Suspended Solids

• Human activity should neither cause the natural ambient level to be raised by more than 30% nor give rise to accumulation of suspended solids which may adversely affect aquatic communities.

Ammonia

• The un-ionised ammoniacal nitrogen level should not be more than 0.021 mg/l calculated as the annual average (arithmetic mean).

Nutrients

• Nutrients should not be present in quantities sufficient to cause excessive or nuisance growth of algae or other aquatic plants; and

• Without limiting the generality of the above point, the level of inorganic nitrogen should not exceed 0.4mg/l, expressed as the annual water column average.

Toxins

• Waste discharges shall not cause the toxins in water to attain such a level as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or other aquatic organisms, with due regard to biologically cumulative effects in food chains and to interactions of toxic substances with each other.

Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems (TM-DSS)

5.1.1.4 Under Section 21 of the WPCO (Cap. 385), Technical Memorandum for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters was issued to control the physical, chemical and microbial quality of effluent discharges into foul sewers, storm water drains, inland and coastal waters. Specific limits apply for different areas are different between surface waters and sewers. The limits vary with the effluent flow rate. Standards for effluent discharged into the inshore waters and marine waters of North Western WCZ are summarized in Table 5.2 and Table 5.3.

Table 5.2 Standards for Effluents Discharged into the Inshore Waters of North Western Control Zones

Flow rate (m^3/day)	≤10	>10 and ≤200	>200 and ≤400	>400 and ≤600	>600 and ≤800	>800 and ≤1000	>1000 and ≤1500	>1500 and ≤2000	>2000 and ≤3000
pH (pH units)	6-9	6-9	6-9	6-9	6-9	6-9	6-9	6-9	6-9
Temperature (¢XC)	40	40	40	40	40	40	40	40	40
Colour (lovibond units) (25mm cell length)	1	1	1	1	1	1	1	1	1
Suspended solids	50	30	30	30	30	30	30	30	30
BOD	50	20	20	20	20	20	20	20	20
COD	100	80	80	80	80	80	80	80	80
Oil & Grease	30	20	20	20	20	20	20	20	20
Iron	15	10	10	7	5	4	3	2	1
Boron	5	4	3	2	2	1.5	1.1	0.8	0.5
Barium	5	4	3	2	2	1.5	1.1	0.8	0.5
Mercury	0.1	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001
Cadmium	0.1	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001
Other toxic metals individually	1	1	0.8	0.7	0.5	0.4	0.3	0.2	0.15
Total toxic metals	2	2	1.6	1.4	1	0.8	0.6	0.4	0.3
Cyanide	0.2	0.1	0.1	0.1	0.1	0.1	0.05	0.05	0.03
Phenols	0.5	0.5	0.5	0.3	0.25	0.2	0.1	0.1	0.1
Sulphide	5	5	5	5	5	5	2.5	2.5	1.5
Total residual chlorine	1	1	1	1	1	1	1	1	1
Total nitrogen	100	100	80	80	80	80	50	50	50
Total phosphorus	10	10	8	8	8	8	5	5	5
Surfactants (total)	20	15	15	15	15	15	10	10	10
E. coli (count/100ml)	1000	1000	1000	1000	1000	1000	1000	1000	1000

Note:

All units in mg/L unless otherwise stated; all figures are upper limits unless otherwise indicated.

Table 5.3 Standards for Effluents Discharged into the Marine Waters of North Western Control Zone

Flow rate (m^3/day)	≤10	>10 and ≤200	>200 and ≤400	>400 and ≤600	>600 and ≤800	>800 and ≤1000	>1000 and ≤1500	>1500 and ≤2000	>2000 and ≤3000
pH (pH units)	6-10	6-10	6-10	6-10	6-10	6-10	6-10	6-10	6-10
Temperature (¢XC)	45	45	45	45	45	45	45	45	45
Colour (lovibond units) (25mm cell length)	4	1	1	1	1	1	1	1	1
Suspended solids	500	500	500	300	200	200	100	100	50
BOD	500	500	500	300	200	200	100	100	50
COD	1000	1000	1000	700	500	400	300	200	150
Oil & Grease	50	50	50	30	25	20	20	20	20
Iron	20	15	13	10	7	6	4	3	2
Boron	6	5	4	3.5	2.5	2	1.5	1	0.7
Barium	6	5	4	3.5	2.5	2	1.5	1	0.7
Mercury	0.1	0.1	0.1	0.001	0.001	0.001	0.001	0.001	0.001
Cadmium	0.1	0.1	0.1	0.001	0.001	0.001	0.001	0.001	0.001
Other toxic metals individually	2	1.5	1.2	0.8	0.6	0.5	0.32	0.24	0.16
Total toxic metals	4	3	2.4	1.6	1.2	1	0.64	0.48	0.32
Cyanide	1	0.5	0.5	0.5	0.4	0.3	0.2	0.15	0.1
Phenols	0.5	0.5	0.5	0.3	0.25	0.2	0.13	0.1	0.1
Sulphide	5	5	5	5	5	5	2.5	2.5	1.5
Total residual chlorine	1	1	1	1	1	1	1	1	1
Total nitrogen	100	100	80	80	80	80	50	50	50
Total phosphorus	10	10	8	8	8	8	5	5	5
Surfactants (total)	30	20	20	20	15	15	15	15	15
E. coli (count/100ml)	4000	4000	4000	4000	4000	4000	4000	4000	4000

Note:

All units in mg/L unless otherwise stated; all figures are upper limits unless otherwise indicated.

ProPECC PN 1/94 ¡§Construction Site Drainage¡¨

5.1.1.5 Professional Persons Environmental Consultative Committee Practice Notes (ProPECC PN1/94) on Construction Site Drainage provides guidelines for the handling and disposal of construction discharges. This note is applicable for control of site runoff and wastewater generated during the construction phase of the Project.

5.1.1.6 The types of discharges from construction sites outlined in the ProPECC PN1/94 that are relevant to this study would include:

¡P Surface run-off;

¡P Boring and drilling water;

¡P Wastewater from concrete batching and precast concrete casting;

¡P Wheel washing water; and

¡P Wastewater from construction activities and site facilities.

WSD Water Quality Criteria for Salt Water Intakes

5.1.1.7 The criteria for assessing the water quality impact on the Water Supplies Department (WSD) seawater intakes are based on the Water Quality Criteria of Seawater for Flushing Supply (at intake point) issued by the WSD and are summarized in Table 5.4a.

Table 5.4a WSD Water Quality Criteria for Salt Water Intakes

Parameter	Concentration
Colour	< 20 H.U.
Turbidity	< 10 N.T.U.
Threshold Odour No.	< 100
Ammonia Nitrogen	< 1 mg/l
Suspended Solids	< 10 mg/l
Dissolved Oxygen	> 2 mg/l
Biochemical Oxygen Demand	< 10 mg/l
Synthetic Detergents	< 5 mg/l
E. coli.	< 20,000 cfu/100 ml

Water Quality Criteria for Seawater Intakes in Castle Peak Power Station and Black Point Power Station

5.1.1.8 As advised by the relevant operator, the criteria for assessing the water quality impact on the cooling seawater intakes in Castle Peak Power Station and Black Point Power Station are summarized in Table 5.4b.

Table 5.4b Salt Water Criteria for Salt Water Intakes at Castle Peak Power Station and Black Point Power Station

Parameter	Level
Temp	17-30 degC
Suspended Solids	< 764 mg/l (<700 mg/l for SS elevation)

5.1.2 Other Guidelines and Criteria

Assessment Criteria for Heavy Metals and Trace Organics

5.1.2.1 There is no existing legislation or guideline for heavy metals and trace organics (PCBs and PAHs) in Hong Kong waters. According to the common practices in previous EIA studies, conservative criteria were set out by comparing different countries standards such as EU, USA, UK and Australia. The lowest values from various international standards have been adopted as the assessment criteria. The adopted criteria for heavy metals and trace organics are presented in Table 5.5.

Table 5.5: Proposed Assessment Criteria for Heavy Metal and Trace Organics

Heavy Metal/Trace Organics	Proposed Criteria (mg/l)	Reference
Arsenic	25	1
Cadmium	0.2	2
Chromium	15	1
Copper	3.1	3
Lead	7.2	2
Mercury	0.05	2
Nickel	8.2	3
Silver	1.9	4
Zinc	10	1
Total PAHs	3.0	6
PCBs	0.03	3

References:

[1] UK Council Directive on the quality required of shellfish waters (Shellfish Waters Directive), http://evidence.environment-agency.gov.uk/ChemicalStandards/ChemicalsByName.aspx

[2] Directive 2008/105/EC of the European Parliament and of the Council of 16 December 2008 on environmental quality standards in the field of water (2008/105/EC), http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:348:0084:0097:EN:PDF

[3] The USEPA Criterion Continuous Concentration (CCC)

[4] The USEPA Criteria Maximum Concentration (CMC)

[6] Total PAH consist of the combination of individual components including acenaphthene, acenaphthylene, anthracene, fluorene, naphthalene, phenanthrene, benzo[a]anthracene, benzo[a]pyrene, chrysene, dibenzo]a,h]anthracene, fluoranthene, pyrene, benzo[b]fluoranthene, benzo[k] fluoranthen, indeno[1,2,3-c,d]pyrene and benzo[g,h,i]perylene. According to Australian Water Quality Guidelines for Fresh and Marine Waters, the criterion of naphthalene is 3.0 µg/L for fresh water aquatic ecosystem conservations.

[7] According to Australian Water Quality Guidelines for Fresh and Marine Waters, the criterion of copper is 5.0 µg/L for irrigation and aquaculture purpose.

Tolerant Deposition Rate for Benthic Ecology

5.1.2.2 Deposition of fine sediment in ecologically sensitive areas including coral sites could have adverse impact on the marine ecosystem. In previous studies^[1],[2],[3], an indicator level above which sustained deposition could harm sediment sensitive hermatypic corals of 200g/m²/day has been used. Typical soft corals in the north western coastal waters where the sediment regime is more dynamic than in other parts of Hong Kong¡¦s coastal waters, are expected to be more tolerant to sediment deposition. Hence, criterion of 200g/m²/day would be adopted for this Study.

5.2 Baseline Conditions

5.2.1 Assessment Area

5.2.1.1 In accordance with Clause 3.4.3.2 of the EIA Study Brief, water quality impact assessment has been carried out in the study area covering the North Western, North Western Supplementary and Western Buffer WCZs. The study area is shown in Figure 1.1.

5.2.2 Hydrological Conditions

5.2.2.1 The North Western waters are situated in the Pearl River Estuary and are heavily influenced by the massive freshwater flows from Guangdong Province. Ebb tide currents are towards the southeast whilst the flood tide currents to the northwest. The area shows a distinct seasonality as a result of the seasonal influx of freshwater from Pearl River. The estuarine influence is especially pronounced in the wet season when the freshwater flows are greatest. Moreover, strong salinity and temperature stratification are observed. During dry season, water conditions are more typical. Salinity and other parameters vary less with depth.

5.2.2.2 The proposed development is located to the south of BCF Island. According to HZMB EIAs studies (AEIAR-145/2009, AEIAR-144/2009), the peak current velocities in Urmston Road could be up to more than 1.3 m/s, whilst the current in the areas near to the project area have been predicted to be less than 0.4 m/s.

5.2.2.3 The catchment of Tung Chung Stream covers Pak Kung Au, Tei Tong Tsai and east of Ngong Ping. Tung Chung Stream is mainly natural, except for an engineered channel sections along Shek Lau Po in east tributary. According to 2014 EPD¡¦s monitoring data, the average flow rates for west and east tributaries are 43 L/s and 53 L/s at TC1 and TC2 monitoring stations respectively.

5.2.2.4 Tung Chung Bay is located between the mouth of Tung Chung Stream and Airport Channel. On comparing to the tidal current at Airport Channel, the water flow of runoff from Tung Chung Stream is considered negligible.

5.2.2.5 Tai Ho Bay is located at the mouth of Tai Ho Stream and to the south of the Siu Ho Wan MTR Depot. The bay is currently connected to the open sea via an opening of approximately 20m wide underneath a short section of deck of NLH. The runoff from Tai Ho Stream is relatively small when compared to the tidal current along Urmston Road or to the south of HKBCF Island. Hence, Tai Ho Bay has an engulfed bayshore hydrological regime controlled by tidal variation at the 20m wide opening.

5.2.3 Summary of Latest Baseline Water Quality Data

5.2.3.1 The Pearl River carries heavy loads of suspended sediment and nutrients. The concentrations of these parameters within North Western waters are generally higher than those in the southern or eastern of Hong Kong waters in which oceanic influence is more pronounced.

5.2.3.2 The latest water quality monitoring data in 2014 was adopted to determine the ambient water quality. Details of marine water quality monitoring data are presented in Table 5.6a and Table 5.6b. According to the Marine Water Quality in Hong Kong 2014, the North Western WCZ attained an overall WQO compliance rate of 61% in 2014 as compared with 72% in 2013. The Western Buffer WCZ attained an overall WQO compliance rate of 83% in 2014 as compared with 92% in 2013. The main reason for non-compliance was due to the high concentration of TIN which was associated with the higher background nutrient level in the Pearl River Delta.

Table 5.6a Summary of EPD¡¦s Routine Marine Water Quality Data for North Western Water Quality Control Zone in 2014

Parameters		North Western WCZ ^[1][2]
		NM1	NM2	NM3	NM5	NM6	NM8
Temperature (¢XC)		23.4	23.9	23.9	24.0	24.3	23.8
		(17.2 - 28.9)	(17.2 - 29.0)	(17.3 - 28.9)	(17.3 - 29.0)	(17.1 - 30.2)	(17.1 - 29.0)
Salinity		30.2	28.3	28.0	27.1	25.3	28.5
		(25.2 - 32.3)	(19.5 - 32.4)	(19.7 - 32.4)	(20.4 - 32.2)	(10.1 - 32.5)	(18.6 - 32.9)
Dissolved Oxygen (mg/L)	Depth Average	5.6	5.8	5.8	5.7	6.3	6.2
		(3.2 - 8.5)	(3.8 - 8.3)	(3.8 - 9.0)	(3.9 - 9.8)	(4.4 - 8.3)	(4.3 - 9.0)
	Bottom	5.4	5.7	5.7	5.6	6.3	5.8
		(1.9 - 9.5)	(3.2 - 9.5)	(2.9 - 9.9)	(2.8 - 9.5)	(4.2 - 9.2)	(0.8 - 9.4)
Dissolved Oxygen (% Saturation)	Depth Average	77	80	80	77	86	85
		(46 - 108)	(55 - 106)	(55 - 114)	(57 - 125)	(63 - 107)	(62 - 115)
	Bottom	75	79	79	77	86	80
		(27 - 121)	(47 - 120)	(42 - 126)	(41 - 121)	(61 - 116)	(12 - 121)
pH		7.9	7.9	7.9	7.8	7.9	8.0
		(7.6 - 8.0)	(7.5 - 8.1)	(7.5 - 8.1)	(7.4 - 8.1)	(7.4 - 8.1)	(7.6 - 8.1)
Secchi Disc Depth (m)		2.8	2.5	2.5	2.3	2.2	2.1
		(1.6 - 5.0)	(1.0 - 5.0)	(1.3 - 5.0)	(1.4 - 4.5)	(1.2 - 4.0)	(1.2 - 3.0)
Turbidity (NTU)		4.8	3.6	5.8	6.3	7.0	7.3
		(0.7 - 17.0)	(1.0 - 7.9)	(0.9 - 20.3)	(2.3 - 14.7)	(1.2 - 28.8)	(3.0 - 14.3)
SS (mg/L)		6.6	4.3	7.6	6.8	8.6	9.0
		(1.1 - 25.7)	(1.5 - 12.3)	(2.0 - 30.0)	(2.8 - 20.7)	(2.6 - 44.0)	(2.1 - 26.7)
5-day Biochemical Oxygen Demand (mg/L)		0.7	0.8	0.8	0.8	1.0	0.8
		(0.4 - 1.7)	(0.4 - 1.8)	(0.4 - 2.1)	(0.4 - 2.1)	(0.4 - 2.0)	(0.4 - 1.5)
Ammonia Nitrogen (mg/L)		0.093	0.107	0.108	0.122	0.091	0.041
		(0.031 - 0.176)	(0.014 - 0.260)	(0.006 - 0.277)	(0.005 - 0.297)	(<0.005 - 0.243)	(0.006 - 0.094)
Unionised Ammonia (mg/L)		0.003	0.003	0.003	0.004	0.003	0.002
		(0.001 - 0.006)	(<0.001 - 0.008)	(<0.001 - 0.008)	(<0.001 - 0.008)	(<0.001 - 0.008)	(<0.001 - 0.004)
Nitrite Nitrogen (mg/L)		0.058	0.081	0.091	0.108	0.108	0.067
		(0.023 - 0.115)	(0.024 - 0.233)	(0.022 - 0.263)	(0.022 - 0.323)	(0.016 - 0.270)	(0.011 - 0.163)
Nitrate Nitrogen (mg/L)		0.268	0.394	0.426	0.48	0.544	0.364
		(0.067 - 0.603)	(0.051 - 0.967)	(0.056 - 0.997)	(0.047 - 1.010)	(0.044 - 1.370)	(0.014 - 1.180)
Total Inorganic Nitrogen (mg/L)		0.42	0.58	0.63	0.71	0.74	0.47
		(0.15 - 0.71)	(0.12 - 1.13)	(0.14 - 1.18)	(0.13 - 1.26)	(0.10 - 1.51)	(0.04 - 1.28)
Total Kjeldahl Nitrogen (mg/L)		0.27	0.30	0.29	0.31	0.28	0.20
		(0.18 - 0.41)	(0.17 - 0.44)	(0.17 - 0.42)	(0.19 - 0.47)	(0.14 - 0.44)	(0.13 - 0.35)
Total Nitrogen (mg/L)		0.59	0.78	0.81	0.89	0.93	0.63
		(0.36 - 0.86)	(0.33 - 1.32)	(0.33 - 1.40)	(0.31 - 1.48)	(0.25 - 1.72)	(0.21 - 1.47)
Orthophosphate Phosphorus (mg/L)		0.021	0.023	0.025	0.028	0.022	0.015
		(0.010 - 0.032)	(0.008 - 0.041)	(0.008 - 0.043)	(0.008 - 0.050)	(0.006 - 0.041)	(0.006 - 0.030)
Total Phosphorus (mg/L)		0.04	0.04	0.04	0.05	0.04	0.03
		(<0.02 - 0.07)	(<0.02 - 0.05)	(<0.02 - 0.06)	(<0.02 - 0.06)	(<0.02 - 0.07)	(<0.02 - 0.06)
Silica (as SiO2) (mg/L)		1.59	2.08	2.23	2.42	2.71	1.93
		(<0.05 - 3.33)	(<0.05 - 4.60)	(<0.05 - 4.80)	(0.05 - 4.93)	(0.05 - 6.53)	(0.05 - 5.87)
Chlorophyll-a (£gg/L)		2	2.3	2.7	3.3	3.8	3.8
		(0.4 - 6.4)	(0.3 - 7.1)	(0.3 - 11.0)	(0.3 - 14.3)	(0.5 - 13.7)	(0.3 - 12.3)
E.coli (count/100mL)		300	71	110	190	22	3
		(36 - 2200)	(7 - 850)	(8 - 1100)	(10 - 4100)	(4 - 180)	(<1 - 11)
Faecal Coliforms (count/100mL)		570	150	230	400	48	7
		(99 - 3900)	(24 - 1500)	(18 - 2300)	(16 - 6800)	(6 - 260)	(1 - 35)

Notes:

[1] Data presented are depth averaged and are the annual arithmetic mean except for E. coli (geometric mean).

[2] Data in brackets indicate ranges.

[3] Extracted from EPD Marine Water Quality in Hong Kong 2014

Table 5.6b Summary of EPD¡¦s Routine Marine Water Quality Data for Western Buffer Water Quality Control Zone in 2014

Parameters		Western Buffer WCZ ^[1][2]
		WM1	WM2	WM3	WM4
Temperature (¢XC)		23	23.3	23.2	23.2
		(16.4 - 28.8)	(16.5 - 28.7)	(16.6 - 28.8)	(16.4 - 28.8)
Salinity		32.7	31.9	31.8	31.7
		(31.0 - 33.5)	(29.3 - 33.3)	(29.4 - 33.1)	(28.7 - 33.2)
Dissolved Oxygen (mg/L)	Depth Average	6.2	5.9	5.7	5.5
		(3.1 - 7.7)	(3.2 - 8.0)	(3.5 - 7.4)	(3.1 - 7.0)
	Bottom	6.2	6.1	5.9	5.8
		(2.5 - 8.2)	(3.0 - 8.0)	(2.6 - 7.8)	(2.5 - 7.9)
Dissolved Oxygen (% Saturation)	Depth Average	87	82	80	76
		(45 - 101)	(47 - 100)	(51 - 94)	(46 - 90)
	Bottom	87	85	82	81
		(35 - 105)	(43 - 103)	(38 - 99)	(36 - 99)
pH		7.9	7.9	7.9	7.9
		(7.7 - 8.2)	(7.6 - 8.2)	(7.6 - 8.1)	(7.6 - 8.2)
Secchi Disc Depth (m)		3.2	3.1	2.7	2.8
		(1.5 - 5.0)	(1.6 - 4.5)	(2.0 - 4.0)	(1.7 - 4.0)
Turbidity (NTU)		3.7	2.6	3.8	4.7
		(1.0 - 6.7)	(1.0 - 4.6)	(1.5 - 7.6)	(1.6 - 14.6)
SS (mg/L)		5	3.7	5.4	6.6
		(1.6 - 16.0)	(1.6 - 11.3)	(2.3 - 15.3)	(2.1 - 16.0)
5-day Biochemical Oxygen Demand (mg/L)		0.6	0.7	0.7	0.7
		(0.3 - 1.2)	(0.3 - 1.1)	(0.3 - 1.1)	(0.3 - 2.9)
Ammonia Nitrogen (mg/L)		0.039	0.093	0.135	0.108
		(0.011 - 0.086)	(0.024 - 0.180)	(0.045 - 0.270)	(0.038 - 0.210)
Unionised Ammonia (mg/L)		0.001	0.003	0.004	0.003
		(<0.001 - 0.004)	(<0.001 - 0.006)	(0.001 - 0.009)	(<0.001 - 0.007)
Nitrite Nitrogen (mg/L)		0.018	0.031	0.033	0.038
		(0.004 - 0.033)	(0.005 - 0.091)	(0.006 - 0.079)	(0.005 - 0.101)
Nitrate Nitrogen (mg/L)		0.071	0.132	0.141	0.161
		(0.010 - 0.137)	(0.036 - 0.310)	(0.043 - 0.313)	(0.047 - 0.333)
Total Inorganic Nitrogen (mg/L)		0.13	0.26	0.31	0.31
		(0.05 - 0.22)	(0.13 - 0.42)	(0.17 - 0.48)	(0.17 - 0.51)
Total Kjeldahl Nitrogen (mg/L)		0.25	0.24	0.3	0.26
		(0.09 - 1.14)	(0.14 - 0.33)	(0.18 - 0.47)	(0.14 - 0.40)
Total Nitrogen (mg/L)		0.34	0.41	0.48	0.45
		(0.16 - 1.27)	(0.29 - 0.57)	(0.29 - 0.68)	(0.30 - 0.69)
Orthophosphate Phosphorus (mg/L)		0.012	0.017	0.021	0.019
		(0.006 - 0.017)	(0.007 - 0.025)	(0.010 - 0.033)	(0.006 - 0.027)
Total Phosphorus (mg/L)		0.02	0.03	0.04	0.04
		(<0.02 - 0.04)	(0.02 - 0.05)	(0.03 - 0.05)	(0.03 - 0.05)
Silica (as SiO2) (mg/L)		0.77	1.03	1.09	1.17
		(0.12 - 1.60)	(0.12 - 2.43)	(0.14 - 2.37)	(0.11 - 2.70)
Chlorophyll-a (£gg/L)		2.7	2.8	2.2	2.2
		(0.9 - 7.3)	(0.4 - 9.3)	(0.5 - 11.1)	(0.2 - 11.6)
E.coli (count/100mL)		66	160	580	170
		(13 - 340)	(5 - 7800)	(86 - 4000)	(77 - 300)
Faecal Coliforms (count/100mL)		150	300	1200	340
		(45 - 550)	(6 - 15000)	(200 - 9200)	(160 - 700)

Notes:

[1] Data presented are depth averaged and are the annual arithmetic mean except for E. coli (geometric mean).

[2] Data in brackets indicate ranges.

[3] Extracted from EPD Marine Water Quality in Hong Kong 2013

5.2.3.3 EPD also conducts routine river quality monitoring in Hong Kong. Tung Chung Stream is the major river closest to the assessment area. Figure 5.1 shows three EPD river monitoring stations (TC1, TC2 and TC3) in Tung Chung Stream. According to the River Water Quality in Hong Kong 2013, the WQO compliance for Tung Chung Stream reached 99%, higher than that for year 2012 which was 97%. Details of Tung Chung Stream water quality monitoring data is presented in Table 5.7.

5.2.3.4 The EPD sea bottom sediment quality monitoring data in the North Western and Western Buffer WCZs are presented in Table 5.8 and Table 5.9 respectively. According to EPD Marine Water Quality Report 2013, the levels of toxic substance in marine water met local and international levels for protection of marine life and human health.

5.2.3.5 A summary of beach water quality monitoring data routinely monitored by EPD at relevant monitoring stations is presented in Table 5.10 and Table 5.11. All 41 gazetted beaches in Hong Kong complied with the WQO in 2013. The E. coli count in the Tuen Mun District ranged from 39 to 78 counts per 100ml in 2013. All the beaches along the Tuen Mun coast received ¡§Fair¡¨ annual ranking. The E. coli count in the Tsuen Wan District ranged from 41 to 135 counts per 100ml in 2013. All the beaches along the Tsuen Wan area received ¡§Fair¡¨ annual ranking. Besides, the annual E.coli levels at the eight Tsuen Wan beaches have dropped and met the WQO since Year 2010 as a result of the operation of the Advanced Disinfection Facilities at Stonecutters Island STW.

Pore Water Test Results from Present Study

5.2.3.6 Sediment samples were collected at the proposed site of reclamation. Pore water tests were conducted for the following parameters:

¡P Heavy metals and metalloid including cadmium, chromium, copper, mercury, nickel, lead, zinc, silver and arsenic;

¡P Organic micro-pollutants including PCB, PAH, Organichlorine Pesticides (OC); and

¡P NO₃-N, NO₂-N, NH₃-N, total phosphorus, Reactive Phosphorus.

5.2.3.7 The Pore Water Test Results for the present study are summarized in Table 5.12. The sampling locations and details are presented in Appendix 5.3. TIN will be estimated based on the measurement results of NO₃-N, NO₂-N, and NH₃-N. UIA will be estimated based on the measurement results of NH₃-N. As shown in Appendix 5.3, Organichlorine Pesticides (OC) have been measured in pore water test. They were below detection limit.

5.2.3.8 The results of Pore Water Test are checked against the heavy metals and nutrients criteria presented in Table 5.5. The parameters that exceed the water quality criteria include:

Pore Water Test: As, TIN and NH₃-N.
Subject to the water quality modelling result at the sensitive receivers, during construction phase, mitigation measures may be required to minimize the release of contaminants.

Non-Statutory Marine Environmental Monitoring for Hong Kong International Airport

5.2.3.9 The Airport Authority Hong Kong has conducted four rounds of monitoring since 2002. According to the 3RS EIA, a non-statutory marine environmental monitoring update for the marine environment surrounding HKIA, including the Southern Sea Channel and East Tung Chung Bay, was carried out. The study consisted of marine water quality monitoring and marine sediment quality monitoring. The marine water quality information provides a useful comparison as the monitoring locations in that study are much closer to the boundary of the present study.

5.2.3.10 According to the 3RS EIA, water quality monitoring survey has been carried out between November 2002 and January 2011. The water quality monitoring locations are shown in Appendix 5.1b. The water quality monitoring results are presented in Table 5.13.

5.2.3.11 The marine water quality monitoring results indicated that most of the water quality parameters recorded at their Control and Impact Stations would generally comply with the relevant North Western WCZ WQOs, except for TIN. There are some irregular exceedance in salinity, DO and SS during 2003-2011. For TIN, exceedance were observed in wet season, which may be due to the influence from Pearl River.

Water Quality Monitoring for New CMPs at East of Sha Chau

5.2.3.12 Routine water quality monitoring has been conducted by CEDD throughout the operation of the Contaminated Mud Pits at Airport East / East Sha Chau. The monitoring is conducted at a frequency of once per quarter and at three monitoring locations. When comparing the results with the SS criteria (30 % of the 90th percentile at the nearest EPD monitoring station) set in Table 5.18 for NM3 and NM6, it was observed that all SS elevations would comply with the WQO criteria. The water quality monitoring data is summarized in Table 5.14.

5.2.3.13 Water quality monitoring has also been conducted during the construction works for the Contaminated Mud Pit V at East of Sha Chau. Water quality monitoring was commenced in September 2009. The monitoring was conducted at three water depths (surface, mid-depth and bottom) at a frequency of three days per week, under mid-flood and mid-ebb tides. The results are shown in Table 5.15. In general, the impact water quality monitoring results for impact station complied with the North Western WCZ WQOs.

Table 5.7 Summary of EPD¡¦s routine river water quality data at Tung Chung Stream in 2014

Parameter	Tung Chung Stream ^[1][2][5]
	TC1	TC2	TC3
Dissolved oxygen (mg/L)	7.9	8.1	8.3
	(7.4-9.8)	(7.5-11.0)	(7.8-10.2)
pH	6.9	7.3	7.8
	(6.7-7.4)	(6.9-8.1)	(6.7-8.3)
SS (mg/L)	1	3	2
	(<1-6)	(1-5)	(<1-12)
5-day Biochemical Oxygen Demand (mg/L)	<1	<1	5
	(<1-<1)	(<1-2)	(<1-23)
Chemical Oxygen Demand (mg/L)	<2	4	7
	(<2-6)	(<2-11)	(<2-20)
Oil & grease (mg/L)	<0.5	<0.5	<0.5
	(<0.5-0.8)	(<0.5-0.8)	(<0.5-1.0)
Faecal coliforms (cfu/100mL)	510	4,400	61,000
	(15-13,000)	(430-42,000)	(22,000 - 140,000)
E. coli(cfu/100mL)^[4]	48	79	15,000
	(7-2,000)	(12-2,700)	(2,000-71,000)
Ammonia-nitrogen (mg/L)	0.01	0.02	0.64
	(<0.01-0.13)	(<0.01-0.03)	(0.07-1.60)
Nitrate-nitrogen (mg/L)	0.06	0.01	0.10
	(0.01-0.29)	(<0.01-0.24)	(0.05-0.24)
Total Kjeldahl nitrogen (mg/L)	0.12	0.14	1.10
	(<0.05-0.27)	(<0.07-0.28)	(0.21-2.60)
Ortho-phosphate (mg/L)	<0.01	<0.01	0.06
	(<0.01-0.04)	(<0.01-0.02)	(0.01-0.18)
Total phosphorus (mg/L)	<0.02	<0.02	0.11
	(<0.02-0.05)	(<0.02-0.04)	(<0.02-0.35)
Total sulphide (mg/L)	<0.02	<0.02	<0.02
	(<0.02-<0.02)	(<0.02-<0.02)	(<0.02-<0.02)
Aluminium (µg/L)	<50	<50	<50
	(<50-164)	(<50-120)	(<50-134)
Cadmium (µg/L)	<0.1	<0.1	<0.1
	(<0.1-<0.1)	(<0.1-<0.1)	(<0.1-<0.1)
Chromium (µg/L)	<1	<1	<1
	(<1-<1)	(<1-1)	(<1-1)
Copper (µg/L)	<1	<1	1
	(<1-2)	(<1-3)	(<1-5)
Lead (µg/L)	<1	<1	<1
	(<1-1)	(<1-1)	(<1-3)
Zinc (µg/L)	13	<14	10
	(<10-24)	(<10-33)	(<10-38)
Flow (L/s)	43	53	NM ^[3]
	(12-160)	(38-244)

Notes:

[1] Data presented are in annual medians of monthly samples; except those for faecal coliforms and E. coli which are in annual geometric means.

[2] Figures in brackets are annual ranges.

[3] NM indicates no measurement taken.

[4] cfu - colony forming unit.

[5] Equal values for annual medians (or geometric means) and ranges indicate that all data are the same as or below laboratory reporting limits.

[6] Extracted from EPD River Water Quality in Hong Kong 2014

Table 5.8 Summary of EPD¡¦s routine marine sediment quality in North Western Water Control Zone at Selected Stations in 1986 to 2014

Monitoring Stations		NS2 (Pearl Island)			NS3 (Pillar Point)			NS4 (Urmston Road)			NS6 (Chek Lap Kok (North))
		Max	Min	Avg	Max	Min	Avg	Max	Min	Avg	Max	Min	Avg
Zinc	(mg/kg)	180	38	102	160	39	97	180	57	98	130	32	82
Vanadium	(mg/kg)	50	11	33	64	17	39	73	18	33	71	17	35
Total Volatile Solid	( % Solid)	11	4	7	10	3	7	10	3	6	9	2	6
Total Sulphide	(mg/kg)	190	<0	20	130	<0.1	22	220	<0.1	23	51	0	9
Total Solid	(%w/w)	64	35	49	70	38	51	77	34	57	76	37	56
Total Polychlorinated Biphenyls	(£gg/kg)	18	<5	14	23	<5	15	18	<5	14	18	<5	14
Total Phosphorous	(mg/kg)	860	84	211	1200	86	215	1100	77	198	340	73	164
Total Kjeldahl Nitrogen	(mg/kg)	1500	120	381	1200	77	370	810	23	335	860	74	301
Total Cyanide	(mg/kg)	0	0	0	1	0	0	0	0	0	0	0	0
Total Carbon	(%w/w)	1	0	1	2	0	1	1	0	1	1	0	1
Silver	(mg/kg)	1	0	1	1	0	0	1	0	0	1	0	0
Pyrene	(£gg/kg)	26	<5	11	110	<5	16	34	<5	12	31	<5	7
Phenanthrene	(£gg/kg)	180	<5	11	280	<5	15	130	<5	11	37	<5	7
Particle Size Fraction <63 micrometer	(%w/w)	99	18	71	98	5	67	97	12	50	98	10	62
Nickel	(mg/kg)	30	6	20	35	7	20	40	7	18	32	8	19
Mercury	(mg/kg)	0	<0.05	0	1	<0.03	0	0	<0.05	0	0	<0.05	0
Manganese	(mg/kg)	790	250	479	900	230	535	1200	440	639	720	200	478
Lead	(mg/kg)	84	20	42	71	20	40	82	29	42	55	16	34
Iron	(mg/kg)	39000	14000	29966	47000	14000	32102	62000	5500	36775	57000	14000	32769
Indeno(1,2,3-cd)pyrene	(£gg/kg)	15	<5	7	50	<5	9	24	<5	7	8	<3	5
Fluorene	(£gg/kg)	12	<10	10	20	<10	10	13	<10	10	10	<10	10
Fluoranthene	(£gg/kg)	24	<5	10	130	<5	15	30	<5	11	18	<5	6
Electrochemical Potential (mV)		-32	-380	-159	-4	-432	-160	-6	-428	-181	-12	-380	-150
Dry Wet Ratio		1	0	0	1	0	0	1	0	1	1	0	1
Dibenzo(ah)anthracene	(£gg/kg)	5	<5	5	5	<5	5	5	<5	5	5	<5	5
Copper	(mg/kg)	95	7	42	84	8	35	67	5	28	84	7	21
Chrysene	(£gg/kg)	18	<5	7	67	<5	9	18	<5	7	13	<5	5
Chromium	(mg/kg)	57	12	35	61	8	34	68	9	31	61	15	31
Chemical Oxygen Demand	(mg/kg)	20000	5900	13464	23000	140	14204	19000	5600	13288	20000	7400	12935
Cadmium	(mg/kg)	11	<0.1	0	10	<0.1	0	9	<0.1	0	13	<0.1	0
Boron	(mg/kg)	56	9	23	49	1	22	74	1	23	66	7	21
Benzo(k)fluoranthene	(£gg/kg)	9	1	4	38	1	6	14	<1	4	6	<1	2
Benzo(ghi)perylene	(£gg/kg)	19	3	8	59	3	11	23	1	7	11	<1	3
Benzo(b)fluoranthene	(£gg/kg)	22	2	8	77	2	11	30	<1	8	12	<1	4
Benzo(a)pyrene	(£gg/kg)	17	1	7	85	<1	10	17	<1	6	8	<1	2
Benzo(a)anthracene	(£gg/kg)	14	<3	6	73	<3	8	12	<3	5	10	<3	4
Barium	(mg/kg)	49	9	31	55	17	32	64	18	30	56	15	28
Arsenic	(mg/kg)	20	2	10	25	2	12	26	4	12	24	6	12
Anthracene	(£gg/kg)	5	<5	5	15	<5	5	5	<5	5	5	<5	5
Ammonia Nitrogen	(mg/kg)	26	0	5	23	<0.05	7	39	0	9	17	<0.05	4
Aluminium	(mg/kg)	42000	7600	25884	46000	12000	26830	52000	12000	22745	51000	9600	24204
Acenaphthylene	(£gg/kg)	250	<50	65	250	<50	65	250	<50	65	250	<50	65
Acenaphthene	(£gg/kg)	100	<50	54	100	<50	54	100	<50	54	100	<50	54

Notes:

[1] NS2 monitoring data before 1987 is not available.

[2] Both NS3 and NS4 monitoring data started from 1986.

[3] NS6 monitoring data before 1991 is not available.

[4] Extracted from EPD website for Marine Water Quality

Table 5.9 Summary of EPD¡¦s routine marine sediment quality in Western Buffer Water Control Zone at Selected Stations in 1986 to 2014

Monitoring Stations		WS1 (Tsing Yi (South))			WS2 (Hong Kong Island (West))
		Max	Min	Avg	Max	Min	Avg
Zinc	(mg/kg)	190	9	111	170	66	106
Vanadium	(mg/kg)	51	15	33	50	28	37
Total Volatile Solid	( % Solid)	71	1	8	10	4	7
Total Sulphide	(mg/kg)	220	0	64	200	0	27
Total Solid	(%w/w)	79	35	47	54	36	44
Total Polychlorinated Biphenyls	(£gg/kg)	25	<5	16	24	5	15
Total Phosphorous	(mg/kg)	450	48	201	1100	140	225
Total Kjeldahl Nitrogen	(mg/kg)	1100	9	456	1800	260	475
Total Cyanide	(mg/kg)	0	0	0	0	0	0
Total Carbon	(%w/w)	3	0	1	2	0	1
Silver	(mg/kg)	3	0	1	3	0	1
Pyrene	(£gg/kg)	110	<5	24	43	<5	12
Phenanthrene	(£gg/kg)	39	<5	11	39	<5	8
Particle Size Fraction <63 micrometer	(%w/w)	98	27	78	99	66	87
Nickel	(mg/kg)	47	8	22	31	13	23
Mercury	(mg/kg)	2	<0.05	0	1	<0.05	0
Manganese	(mg/kg)	890	33	524	760	440	593
Lead	(mg/kg)	68	<5	40	54	22	40
Iron	(mg/kg)	40000	3400	30214	39000	22000	32310
Indeno(1,2,3-cd)pyrene	(£gg/kg)	55	<5	16	22	<5	8
Fluorene	(£gg/kg)	15	<10	10	11	<10	10
Fluoranthene	(£gg/kg)	90	<5	24	35	<5	12
Electrochemical Potential (mV)		42	-603	-175	58	-762	-146
Dry Wet Ratio		1	0	0	1	0	0
Dibenzo(ah)anthracene	(£gg/kg)	12	<5	5	6	<5	5
Copper	(mg/kg)	280	<1	62	140	17	39
Chrysene	(£gg/kg)	48	<5	12	17	<5	7
Chromium	(mg/kg)	84	13	40	59	23	38
Chemical Oxygen Demand	(mg/kg)	21000	190	14758	21000	3900	13795
Cadmium	(mg/kg)	9	<0.1	0	9	<0	0
Boron	(mg/kg)	47	<1	26	49	11	29
Benzo(k)fluoranthene	(£gg/kg)	33	2	10	14	2	5
Benzo(ghi)perylene	(£gg/kg)	55	2	18	23	2	10
Benzo(b)fluoranthene	(£gg/kg)	63	2	19	25	1	10
Benzo(a)pyrene	(£gg/kg)	74	2	19	26	2	9
Benzo(a)anthracene	(£gg/kg)	55	<3	13	21	<3	6
Barium	(mg/kg)	58	15	35	56	25	38
Arsenic	(mg/kg)	14	2	9	17	1	9
Anthracene	(£gg/kg)	5	<5	5	5	<5	5
Ammonia Nitrogen	(mg/kg)	38	0	10	35	<0.05	6
Aluminium	(mg/kg)	45000	1400	27100	45000	18000	30309
Acenaphthylene	(£gg/kg)	250	<50	65	250	<50	65
Acenaphthene	(£gg/kg)	100	<50	54	100	<50	54

Note:

[1] Both WS1 and WS2 monitoring data started from 1988.

Table 5.10 Summary of EPD¡¦s routine beach water quality in Tuen Mun from 1997 to 2014

E. coli counts per 100ml (annual geometric mean)
Beach	1997	1998	1999	2000	2001	2002	2003	2004	2005	2006	2007	2008	2009	2010	2011	2012	2013	2014
Butterfly	259	121	44	61	74	60	74	55	55	94	84	56	49	30	41	42	71	38
Cafeteria New	309	100	60	51	104	62	80	54	70	120	68	48	38	31	27	47	50	31
Cafeteria Old	435	138	58	57	125	74	76	61	81	150	67	45	46	34	29	48	39	45
Castle Peak	332*	199*	57*	58*	105*	58*	64*	80*	90	139	64	47	35	63	49	48	78	91
Golden	352	98	44	50	87	66	84	46	62	117	87	63	42	37	26	62	45	39
Kadoorie	290	130	109	68	120	114	160	98	117	118	101	87	48	45	37	40	52	37

Source:

EPD Beach Water Quality in Hong Kong 2014

Note:
*The beach was closed in the selected years

Table 5.11 Summary of EPD¡¦s routine beach water quality in Tsuen Wan from 1997 to 2014

E. coli counts per 100ml (annual geometric mean)
Beach	1997	1998	1999	2000	2001	2002	2003	2004	2005	2006	2007	2008	2009	2010	2011	2012	2013	2014
Anglers¡¦	691*	502*	442*	326*	621*	1169*	693*	619*	895*	772*	496*	510*	276*	134*	27*	69*	133	130
Approach	1009*	435*	387*	316*	411*	696*	762*	470*	663*	599*	352*	251*	208*	124*	59	83	106	121
Casam	609	239	231	209	233	741	702*	594*	716*	426*	305*	289*	144*	102*	21	50	71	63
Gemini	458	399	350	258	323	1155	875*	1102*	1042*	853*	566*	481*	410*	137*	19*	40*	135*	110*
Hoi Mei Wan	471	280	109	177	199	547	442*	287*	641*	308*	286*	271*	130*	87*	23	51	86	58
Lido	600	262	231	181	269	683	734*	523*	782*	459*	280*	296*	178*	87*	21	32	53	57
Ma Wan Tung Wan	110	92	51	39	133	201	159	101	132	171	78	53	60	17	10	24	41	31

Source:

EPD Beach Water Quality in Hong Kong 2014

Note:

*The beach was closed in the selected years

Table 5.12 Pore water results from present study

Sampling Location	Metals (£gg/L)								Metalloid (£gg/L)	TKN (mg/L)	NH3-N (mg/L)	NO3-N (mg/L)	NO2-N (mg/L)	TIN ^[1] (mg/L)	UIA ^[2] (mg/L)	Total P (mg/L)	Ortho-P (mg/L)
	Ni	Hg	Cd	Ag	Cr	Cu	Pb	Zn	As
Criteria / Baseline	8.2	0.05	3.1	1.9	15	5	0.5	0.021	25	-	-	-	-	0.5	0.021	-	-
VB1	2	<0.05	<0.2	<1	<1	<1	2.0	0.08	<10	2	1.95	<0.01	<0.01	1.97	0.08	0.1	0.07
VB2	2	<0.05	<0.2	<1	<1	<1	3.1	0.12	<10	3.4	3.03	<0.01	<0.01	3.05	0.12	0.2	0.22
VB3	2	<0.05	<0.2	<1	<1	<1	2.8	0.11	<10	3	2.77	<0.01	<0.01	2.79	0.11	0.4	0.47
VB4	1	<0.05	<0.2	<1	<1	<1	4.0	0.16	<10	4.1	4	<0.01	<0.01	4.02	0.16	0.4	0.33
VB5	1	<0.05	<0.2	<1	<1	<1	12.8	0.50	28	12.8	12.8	<0.01	<0.01	12.82	0.50	1.9	1.7
VB6	2	<0.05	<0.2	<1	<1	<1	2.5	0.10	<10	3.1	2.48	<0.01	<0.01	2.50	0.10	0.2	0.14
VB7	2	<0.05	<0.2	<1	<1	<1	1.3	0.05	<10	2.5	1.32	<0.01	<0.01	1.34	0.05	0.5	0.02
VB8	2	<0.05	<0.2	<1	<1	<1	1.2	0.04	<10	1.8	1.12	0.03	<0.01	1.16	0.04	0.1	0.06
VB9	1	<0.05	<0.2	<1	<1	<1	4.1	0.16	<10	4.1	4.07	<0.01	<0.01	4.09	0.16	0.2	0.3
VB10	2	<0.05	<0.2	<1	<1	<1	5.2	0.20	<10	10.2	5.18	<0.01	0.02	5.21	0.20	1.2	0.03
VB11	2	<0.05	<0.2	<1	<1	<1	1.1	0.04	<10	1.8	1.12	<0.01	<0.01	1.14	0.04	0.2	0.07
VB12	<1	<0.05	<0.2	<1	<1	<1	1.1	0.04	<10	1.5	1.09	<0.01	<0.01	1.11	0.04	0.1	0.09
VB13	1	<0.05	<0.2	<1	<1	<1	0.9	0.04	<10	1.4	0.9	0.02	<0.01	0.93	0.04	0.1	0.04
VB14	2	<0.05	<0.2	<1	<1	<1	1.3	0.05	<10	1.8	1.3	0.02	0.02	1.34	0.05	0.2	0.07
VB15	2	<0.05	<0.2	<1	<1	<1	0.8	0.03	<10	2.1	0.74	<0.01	<0.01	0.76	0.03	0.2	0.01
VB16	1	<0.05	<0.2	<1	<1	1	1.1	0.04	<10	2.1	1.04	<0.01	<0.01	1.06	0.04	0.2	0.02
VB17	2	<0.05	<0.2	<1	<1	<1	4.4	0.17	<10	5.6	4.37	<0.01	<0.01	4.39	0.17	0.2	0.22
VB18	2	<0.05	<0.2	<1	<1	<1	3.6	0.14	<10	3.6	3.55	<0.01	<0.01	3.57	0.14	0.1	0.08
VB19	2	<0.05	<0.2	<1	<1	<1	6.4	0.25	<10	7	6.35	<0.01	<0.01	6.37	0.25	0.2	0.09
VB20	2	<0.05	<0.2	<1	<1	2	1.1	0.04	<10	1.9	1.09	<0.01	<0.01	1.11	0.04	0.2	0.02
VB21	2	<0.05	<0.2	<1	<1	<1	1.0	0.04	<10	2	0.99	<0.01	0.01	1.01	0.04	0.2	0.06
VB22	2	<0.05	<0.2	<1	<1	<1	1.0	0.04	<10	1.9	0.99	<0.01	<0.01	1.01	0.04	0.1	0.01
VB23	1	<0.05	<0.2	<1	<1	<1	1.4	0.06	<10	2.3	1.4	<0.01	<0.01	1.42	0.06	0.2	0.02
VB24	2	<0.05	<0.2	<1	<1	<1	0.9	0.03	<10	0.9	0.84	<0.01	<0.01	0.86	0.03	<0.1	0.03
VB25	2	<0.05	<0.2	<1	<1	<1	1.0	0.04	<10	3	0.95	<0.01	<0.01	0.97	0.04	0.2	0.01
VB26	2	<0.05	<0.2	<1	<1	<1	0.9	0.04	<10	1.2	0.91	<0.01	<0.01	0.93	0.04	0.1	0.04
VB27	2	<0.05	<0.2	<1	<1	<1	1.2	0.05	<10	1.9	1.16	0.02	<0.01	1.19	0.05	0.1	0.06
VB28	2	<0.05	<0.2	<1	<1	<1	1.4	0.05	<10	1.8	1.28	0.06	0.02	1.36	0.05	0.1	0.05
Maximum	2	<0.05	<0.2	<1	<1	2	12.8	0.50	28	12.8	12.8	0.06	0.02	12.82	0.50	1.9	1.7

Notes:

[1] TIN is calculated by summation of NO₂-N, NO₃-N and NH₃-N

[2] UIA is estimated by multiplying a percentage factor to NH₃-N. This factor depends on temp and pH. The average temp and pH from EPD water quality monitoring stations in North Western WCZ are 23.6 degC and 7.9 respectively. According to the ¡§Aqueous Ammonia Equilibrium- Tabulation of Percent Unionized Ammonia¡¨ from USEPA, the conversion factor is 3.93%.

Table 5.13: Summary of water quality parameters recorded from November 2002 to January 2011 for HKIA

Averaging Period	Area	Surface Temp.	Mid-Depth Temp.	Surface Salinity	DO	Turbidity	SS	BOD5	TKN	TIN	TRC
Unit		ºC	ºC	ppt	mg/L	NTU	mg/L	mg/L	mg/L	mg/L	mg/L
WQO		<¡Ó2ºC	<¡Ó2ºC	<¡Ó10%	> 4 mg/L	-	<+30%	-	-	< 0.5 mg/L	-
Nov 2002	Impact	23.6	23.5	31.4	6.2	339.3	10.4	<2	0.4	N/A	N/A
	Control	23.6	23.5	31.4	6.2	390.3	23.0	<2	0.6	N/A	N/A
Jan 2003	Impact	17.8	17.8	28.9	9.2	7.3	13.4	2.0	0.5	N/A	N/A
	Control	17.6	17.5	28.8	9.5	5.3	12.5	2.0	0.5	N/A	N/A
Mar 2003	Impact	21.2	21.0	31.8	7.0	12.4	13.6	<2	0.6	N/A	N/A
	Control	20.9	20.1	31.0	7.0	12.0	15.5	<2	0.6	N/A	N/A
May 2003	Impact	26.3	26.0	24.8	8.5	8.0	6.2	<2	0.1	N/A	N/A
	Control	26.5	25.8	25.7	6.7	-16.6	10.5	<2	0.2	N/A	N/A
Jun 2003	Impact	27.4	27.3	14.9	5.3	15.7	14.2	<2	0.1	N/A	N/A
	Control	27.5	27.4	13.2	5.4	20.0	13.0	<2	0.2	N/A	N/A
Jul 2003	Impact	30.5	30.3	16.0	6.0	24.3	10.4	<2	0.1	N/A	N/A
	Control	29.6	29.0	16.5	4.6	47.7	13.0	<2	0.2	N/A	N/A
Aug 2003	Impact	30.3	30.1	20.7	5.8	21.1	19.8	<2	0.1	N/A	N/A
	Control	30.4	29.4	18.7	4.9	17.5	11.0	<2	0.1	N/A	N/A
Oct 2003	Impact	26.4	26.4	32.0	9.5	9.8	5.8	<2	0.2	N/A	N/A
	Control	26.2	26.1	32.0	8.2	12.4	9.5	<2	0.4	N/A	N/A
Dec 2005	Impact	17.9	17.8	32.7	8.1	5.0	5.8	<2	0.8	0.1	<0.2
	Control	17.9	17.3	32.7	8.7	7.8	8.0	<2	0.8	0.1	<0.2
Feb 2006	Impact	17.7	17.8	30.2	7.1	6.7	7.2	<2	0.3	0.3	<0.2
	Control	17.8	17.8	30.6	7.1	6.8	7.0	<2	0.3	0.3	<0.2
Apr 2006	Impact	22.4	22.2	26.5	6.6	8.0	8.0	<2	0.4	0.8	<0.2
	Control	21.9	21.5	28.0	6.4	7.1	12.5	<2	0.4	0.5	<0.2
Jun 2006	Impact	26.2	26.3	8.8	7.0	6.2	3.6	<2	0.3	1.5	<0.2
	Control	26.3	26.3	8.6	6.5	5.3	4.0	<2	0.3	1.5	<0.2
Aug 2006	Impact	29.8	29.8	11.6	6.5	7.2	6.0	<2	0.1	1.1	<0.2
	Control	29.9	29.8	10.5	6.3	7.2	5.5	<2	0.3	1.2	<0.2
Oct 2006	Impact	28.1	28.0	28.4	5.2	8.0	9.4	<2	0.5	0.6	<0.2
	Control	28.0	27.6	26.9	5.0	5.5	6.0	<2	0.5	0.5	<0.2
Mar 2010	Impact	20.5	20.5	29.2	7.1	11.6	9.2	<2	0.2	0.6	<0.2
	Control	19.8	20	29.1	7.4	14.2	11.5	<2	0.3	0.6	<0.2
May 2010	Impact	26.6	26.4	18.2	5.5	7	7.2	<2	0.4	1.1	<0.2
	Control	25.7	25.1	20.7	5.4	8.8	9	<2	0.4	0.8	<0.2
Jul 2010	Impact	29.2	29.1	9.7	10.8	12.2	12.8	2	0.4	1.1	<0.2
	Control	29.1	29	8.6	9.6	9.7	10	2.5	0.5	1.2	<0.2
Sep 2010	Impact	28.3	27.7	21.7	4.4	12.1	12.4	<2	0.3	1.1	<0.2
	Control	27.9	26.4	21.8	3.4	17.4	18	<2	0.3	0.9	<0.2
Nov 2010	Impact	23.2	23	30.6	6.7	14.7	15.2	<2	0.2	0.3	<0.2
	Control	23.3	23	30.3	6.3	11.7	20	<2	0.3	0.3	<0.2
Jan 2011	Impact	16.8	16.8	32.6	8.6	18.6	25.4	<2	0.2	0.2	<0.2
	Control	17.1	17.1	32.6	8.1	29.8	19	<2	0.2	0.2	<0.2
Average	Impact	24.5	24.4	24.0	7.1	27.8	10.8	<2	0.3	0.7	<0.2
	Control	24.3	24.0	23.9	6.6	31.0	11.9	<2	0.4	0.7	<0.2

Source:
Approved EIA (EIA 223/2014) for Expansion of Hong Kong Airport into a Three-Runway System

Note:

¡± All data are mid-depth average value unless stated otherwise.

¡± Shaded cell represents the value exceeded the relevant WQOs.

Table 5.14 Routine water quality monitoring results from Aug 2006 to May 2013 for new CMPs at East of Sha Chau

	SS	Turbidity	DO	Cr	Cu	Pb	Zn
	(mg/L)	(NTU)	(mg/L)	(£gg/L)	(£gg/L)	(£gg/L)	(£gg/L)
Reference Station	11.21	7.33	6.7	0.63	4.55	1.15	8.93
Mid-field	11.45	7.26	6.65	0.62	4.21	1.27	7.32
Impact Station	11.39	6.93	6.63	0.6	5.07	1.08	8.78

Source: CEDD Routine Water Quality Monitoring at Airport East / East Sha Chau

Table 5.15 Water quality monitoring results from Aug 2006 to May 2013 for new CMPs at East of Sha Chau

Parameter	Near Field Stations	Results (average)
Salinity (ppt)	DS1(Down Stream Station)	24.68
	DS2(Down Stream Station)	24.5
	DS3(Down Stream Station)	24.62
	DS4(Down Stream Station)	24.59
	DS5(Down Stream Station)	24.28
	MW1(Ma Wan Station)	27.69
	US1(Upstream Station)	24.69
	US2(Upstream Station)	24.94
Dissolved Oxygen (mg/L)	DS1(Down Stream Station)	7.13
	DS2(Down Stream Station)	7.15
	DS3(Down Stream Station)	7.07
	DS4(Down Stream Station)	7.07
	DS5(Down Stream Station)	7.11
	MW1(Ma Wan Station)	6.72
	US1(Upstream Station)	7.17
	US2(Upstream Station)	7.14
Turbidity (NTU)	DS1(Down Stream Station)	12.95
	DS2(Down Stream Station)	11.14
	DS3(Down Stream Station)	10.81
	DS4(Down Stream Station)	9.54
	DS5(Down Stream Station)	8.95
	MW1(Ma Wan Station)	5.86
	US1(Upstream Station)	10.94
	US2(Upstream Station)	11.04
pH	DS1(Down Stream Station)	7.8
	DS2(Down Stream Station)	7.8
	DS3(Down Stream Station)	7.79
	DS4(Down Stream Station)	7.79
	DS5(Down Stream Station)	7.78
	MW1(Ma Wan Station)	7.77
	US1(Upstream Station)	7.79
	US2(Upstream Station)	7.79
Suspended Solids (mg/L)	DS1(Down Stream Station)	17.41
	DS2(Down Stream Station)	14.45
	DS3(Down Stream Station)	14.11
	DS4(Down Stream Station)	12.42
	DS5(Down Stream Station)	11.37
	MW1(Ma Wan)	8.52
	US1(Upstream Station)	14.5
	US2(Upstream Station)	14.35

Source:
ERM (2009). Environmental Monitoring and Audit for Contaminated Mud Pit at Sha Chau (2009-2013) ¡V EM&A Impact Results (http://www.cmp-monitoring.com.hk/EM&A%20Data.html).

5.3 Indication Point and Methodology of Quantitative Modelling

5.3.1 General Description

5.3.1.1 As discussed in Section 2.3, the project has been proactively designed to reduce both the ecological and water quality impacts by avoiding any reclamation in TCW.  On comparing to the original scheme with 50ha reclamation (see Section 2), the current scheme with the removal of TCW reclamation, would further improve the ecology and water quality condition on TCW.  However, there would still be a need for a reclamation of 129.1 ha for TCE and Road P1 (Tung Chung ¡V Tai Ho Section).  In order to minimize the potential impacts caused by the reclamation, a number of alternative construction methodologies has been critically examined.  After considering all the options such as fully dredged, partially dredged and non-dredged methods for seawall construction and reclamation, non-dredged method for both the seawall construction and reclamation are recommended so as to minimize the generation of dredged sediment.  Nevertheless, the construction work would still require filling work which would still inevitably generate suspended solids.  Besides, the filling process would also generate pore water from the sediment.  Hence, a quantitative water quality modelling would be required to assess the impacts during the seawall construction and the reclamation process.

5.3.1.2 During the operational phase, the proposed TCE reclamation would have potential impacts on the hydrodynamic conditions and the water quality.  This would need to be quantitatively assessed.  It is noted that all the sewage generated from the additional population and employment would be conveyed to Siu Ho Wan Sewage Treatment Works for treatment before discharge.  However, the surface run-off would still be discharged into the neighbouring water.  The water quality model would therefore need to evaluate the impacts from surface runoff.

5.3.1.3 Irrespective of the construction and operational impacts, the cumulative impacts caused by concurrent projects would need to be considered.  The potential concurrent projects include 3RS, HZMB-HKBCF, HZMB-HKLR, TM-CLKL, etc, which are discussed in the following sections.

5.3.2 Selection of Representative Water Sensitive Receivers

5.3.2.1 Indicator points were selected in the water quality model to provide hydrodynamic and water quality outputs to evaluate water quality impact. The selected indicator points include water quality sensitive receivers (WSRs) and EPD marine water sampling stations.

5.3.2.2 The WSRs in the vicinity of the project area including ecological sensitive area with conservation importance, commercial fishing resources, areas of direct human contact, e.g. bathing beaches, and seawater extraction points are shown in Table 5.16a.

5.3.2.3 In addition to the WSRs, a number of locations of interest within the study area are included as observation points in the assessment as shown in Table 5.16b.

Table 5.16a Summary of the Representative Water Sensitive Receivers

ID	Description	Impact
WSR 01	Yat Tung East Channel	Construction and Operation
WSR 02	Yat Tung West Channel	Construction and Operation
WSR 03	Estuary of Tung Chung Stream	Construction and Operation
WSR 04	Marine Park at Brothers Islands and Tai Mo To (Dolphin Habitat)	Construction and Operation
WSR 05a-b	River Trade Terminal	Construction and Operation
WSR 06	Coral Communities at The Brothers Islands	Construction and Operation
WSR 07	Black Point Power Station Cooling Water Intake	Construction and Operation
WSR 08	Lung Kwu Sheung Tan (non-gazetted beach)	Construction
WSR 10	Sha Chau and Lung Kwu Chau Marine Park	Construction and Operation
WSR 11	Castle Peak Power Station Cooling Water Intake	Construction and Operation
WSR 12	Butterfly Beach	Construction and Operation
WSR 13	WSD Tuen Mun Salt Water Pumping Station with Salt Water Intake	Construction and Operation
WSR 14	Tuen Mun Typhoon Shelter	Construction and Operation
WSR 15	Gazetted Beaches at Tuen Mun	Construction and Operation
WSR 16	Gold Coast Marina	Construction and Operation
WSR 17	WSD Lok On Pai Salt Water Pumping Station with Salt Water Intake	Construction and Operation
WSR 18	Gazetted beaches along Castle Peak Road	Construction and Operation
WSR 19	Gazetted beaches at Ma Wan	Construction and Operation
WSR 20	Ma Wan Fish Culture Zone	Construction and Operation
WSR 21	WSD Sunny Bay Salt Water Pumping Station with Salt Water Intake	Construction and Operation
WSR 22a	Tai Ho Wan Inlet (inside)	Construction and Operation
WSR 22b	Tai Ho Bay (inner), Near Tai Ho Stream SSSI	Construction and Operation
WSR 22c	Tai Ho Wan Inlet (outside)	Construction and Operation
WSR 23	Future Seawater Intake for LLP (Flushing)	Operation
WSR 25	Cooling water intake at Hong Kong International Airport (North)	Construction and Operation
WSR 26	Future Cooling Seawater Intake at Hong Kong International Airport (East)	Construction and Operation
WSR 27	San Tau Beach SSSI	Construction and Operation
WSR 28	Cooling Water Intake at Hong Kong International Airport (South)	Construction and Operation
WSR 29	Hau Hok Wan (Horseshoe Crab Habitat)	Construction and Operation
WSR 30	Sha Lo Wan (Horseshoe Crab Habitat)	Construction and Operation
WSR 31	Sham Wat Wan (Mangrove and Horseshoe Crab Habitat)	Construction and Operation
WSR 32	Tai O (Mangrove Habitat)	Construction and Operation
WSR 33	Tai O Bay	Construction and Operation
WSR 34	Yi O (Mangrove and Horseshoe Crab Habitat)	Construction and Operation
WSR 35	Potential marine park / marine reserve for SW Lantau	Operation
WSR 41	Artificial Reef at Northeast Airport	Construction and Operation
WSR 42	Artificial Reef and coral communities at Sha Chau	Construction and Operation
WSR 43	Proposed Seawater intake for Tung Chung (Flushing)	Operation
WSR 44	Future HKBCF Intake (Flushing)	Construction and Operation
WSR 45	Sham Shui Kok (Dolphin Habitat)	Construction and Operation
WSR 46	Proposed Marina at Tung Chung East Reclamation	Operation

Table 5.16b Summary of the Observation Points

ID	Description
M1-M5	Five corners of Brothers Islands Marine Park
M6-M10	Four corners and southern boundary mid-point of Sha Chau and Lung Kwu Chau Marine Park

5.3.2.4 Figure 5.1 shows the locations of these WSRs. The locations of EPD marine water sampling stations at North Western Water Quality Zone (NM1, NM2, NM3, NM5, NM6, NM8, WM4, TC1, TC2 and TC3) are also shown in the figure for reference.

5.3.2.5 According to the latest design, there would be no seawater cooling discharge from Tung Chung New Town development. In case, there is a need to re-consider the seawater cooling facilities, a separate study shall be conducted by the operator.

5.3.3 Proposed Suspended Solids Criteria for Indicator Points

5.3.3.1 According to WQO, the criteria for SS is defined as ¡§waste discharge not to raise the natural ambient level by 30% nor cause the accumulation of SS which may adversely affect aquatic communities¡¨. It is expected that the North Western WCZ will be affected from the construction works. In order to determine the ambient SS concentrations in the waters likely to be affected by the construction works, water quality monitoring data from NM1, NM2, NM3, NM5, NM6, NM8 and WM4 in the WCZ have been analyzed.

5.3.3.2 EPD marine water quality data in sea surface, mid-depth and the bottom are presented in Table 5.17. The sampling in wet season was taken from April until the end of September in each year.

Table 5.17 SS concentrations from EPD Routine Monitoring Programme (2005-2014)

Station	SS Concentrations (mg/L)
	Surface		Middle		Bottom		Depth Averaged
	Dry Season	Wet Season	Dry Season	Wet Season	Dry Season	Wet Season	Dry Season	Wet Season
NM1	6.0	4.7	8.0	6.3	9.6	11.7	7.9	7.6
	(1.4-22)	(0.9-20)	(0.8-22)	(0.8-27)	(0.9-40)	(1.2-55)	(1.4-27)	(1.1-26)
NM2	5.6	4.5	6.9	4.8	9.8	6.1	7.4	5.2
	(1.3-19)	(1.4-15)	(1.2-28)	(1-17)	(1.5-40)	(1-24)	(1.6-26)	(1.5-15)
NM3	6.2	5.1	8.1	6.3	11.3	9.7	8.5	7.0
	(1.3-18)	(1.2-15)	(1.4-35)	(1.3-22)	(1.5-46)	(1.5-27)	(1.8-31)	(2.1-17)
NM5	7.9	5.8	10.5	7.3	16.3	18.9	11.6	10.7
	(1.6-23)	(1.2-19)	(1.6-29)	(2-22)	(2.6-61)	(2.4-150)	(2-33)	(2.6-54)
NM6	10.6	7.1	11.5	11.5	14.6	6.5	12.2	8.4
	(2.2-40)	(1.6-22)	(2.5-45)	(2-36)	(2.4-52)	(1.6-84)	(2.5-44)	(2.6-34)
NM8	11.9	5.6	14.3	7.6	20.7	15.1	15.6	9.4
	(1.7-50)	(1.3-18)	(2.6-63)	(1.3-30)	(3.8-73)	(2.2-45)	(2.7-59)	(1.9-26)
WM4	4.5	3.8	6.6	5.1	9.0	9.3	6.7	6.1
	(0.9-15)	(0.8-12)	(0.8-23)	(1.1-14)	(2.1-36)	(2.2-20)	(1.4-20)	(2.1-14)

Note:

The data are presented as the arithmetic mean and range (max ¡V min) of the SS concentrations at each station at the three monitoring levels and as the depth averaged concentrations.

5.3.3.3 The 90 percentiles for each station summarized in Table 5.18.

Table 5.18 90^th Percentile SS from EPD Routine Monitoring Programme (2005-2014)

Station	90^th Percentile Suspended Solids Concentrations (mg/L)
	Surface		Middle		Bottom		Depth Averaged
	Dry Season	Wet Season	Dry Season	Wet Season	Dry Season	Wet Season	Dry Season	Wet Season
NM1	11.0	6.7	16.1	11.0	17.1	19.2	14.7	12.0
NM2	9.2	8.1	10.1	8.5	18.4	9.6	13.0	8.2
NM3	11.0	8.1	13.0	10.0	21.1	17.1	14.3	11.5
NM5	14.0	9.7	19.1	13.2	32.2	36.2	20.7	20.2
NM6	21.4	8.9	25.2	11.0	32.0	23.0	26.2	14.6
NM8	23.1	10.0	26.2	16.3	42.4	31.4	30.0	18.7
WM4	8.0	5.8	11.1	9.0	17.2	17.0	12.2	9.6

5.3.3.4 The SS criteria were derived from 30% of the 90th Percentile SS concentration measurement at the corresponding EPD¡¦s Monitoring Stations (Table 5.18) and are summarized in Table 5.19. The SS criteria are the allowable elevation of SS.

Table 5.19 Suspended solids criteria (mg/L) for the construction phase impacts

Station	Suspended Solids Criteria (mg/L)
	Surface		Middle		Bottom		Depth Averaged
	Dry Season	Wet Season	Dry Season	Wet Season	Dry Season	Wet Season	Dry Season	Wet Season
NM1	3.3	2.0	4.8	3.3	5.1	5.8	4.4	3.6
NM2	2.8	2.4	3.0	2.6	5.5	2.9	3.9	2.5
NM3	3.3	2.4	3.9	3.0	6.3	5.1	4.3	3.5
NM5	4.2	2.9	5.7	4.0	9.7	10.9	6.2	6.1
NM6	6.4	2.7	7.6	3.3	9.6	6.9	7.9	4.4
NM8	6.9	3.0	7.9	4.9	12.7	9.4	9.0	5.6
WM4	2.4	1.7	3.3	2.7	5.2	5.1	3.7	2.9

5.3.3.5 The corresponding SS criterion for each WSR is presented in Table 5.20.

Table 5.20 Suspended solids criteria (mg/L) for the construction phase impacts at the water sensitive receivers

WSR	Corresponding EPD¡¦s Stations	Cooling/ Flushing Seawater Intake	Suspended Solids Criteria (mg/L)
			Dry Season				Wet Season
			S	M	B	DA	S	M	B	DA
WSR 01	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 02	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 03	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 04	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 05a-b	NM3	-	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5
WSR 06	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 07 ^[1]	-	Cooling	700	700	700	700	700	700	700	700
WSR 08	NM5	-	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1
WSR 10	NM5	-	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1
WSR 11 ^[1]	-	Cooling	700	700	700	700	700	700	700	700
WSR 12	NM3	-	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5
WSR 13 ^[2]	-	Flushing	10	10	10	10	10	10	10	10
WSR 14	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 15	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 16	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 17 ^[2]	-	Flushing	10	10	10	10	10	10	10	10
WSR 18	NM1	-	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6
WSR 19	WM4	-	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9
WSR 20	WM4	-	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9
WSR 21 ^[2]	-	Flushing	10	10	10	10	10	10	10	10
WSR 22a	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 22b	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 22c	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 23 ^[2]	-	Flushing	10	10	10	10	10	10	10	10
WSR 25	NM3	Cooling	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5
WSR 26	NM3	Cooling	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5
WSR 27	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 28	NM8	Cooling	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 29	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 30	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 31	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 32	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 33	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 34	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 35	NM8	-	6.9	7.9	12.7	9	3	4.9	9.4	5.6
WSR 41	NM5	-	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1
WSR 42	NM5	-	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1
WSR 44 ^[2]	-	Flushing	10	10	10	10	10	10	10	10
WSR 45	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5
WSR 46	NM2	-	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5

Notes:

[1] This is a specific requirement for the Castle Peak Power Station intake and the SS elevation should be maintained at below 700 mg/L

[2] WSD¡¦s Water Quality Criteria for Flushing Water at Sea Water Intakes has been adopted for seawater intake for flushing. Values present in the table represent absolute values.

5.3.4 Hydrodynamic Modelling

Grid Refinement

5.3.4.1 The model adopted in the previous approved HZMB BCF EIA has been reviewed and refined to simulate the hydrodynamic and water quality impact for the construction and operational phases in this study. The Delft3D-FLOW module was used for hydrodynamic simulations. The grid layout is shown in Appendix 5.2a. Bathymetry data from electronic navigational charts in 2011 from Marine Department was used to update the bathymetry in the study area.

Modeling Parameter

5.3.4.2 The reference level of the refined model is the principle Datum Hong Kong and the depth data is relative to this datum.

5.3.4.3 The simulation period, meteorological conditions, initial conditions and boundary conditions in the approved Regional Update Model was adopted for the refined model. The typical simulation was carried out for wet and dry seasons over a 15-day spring-neap tidal cycle with spin-up period of at least 15 days.

5.3.4.4 The time step in hydrodynamic model was set to 1 minute and the adequacy of adopted time step could be verified from the stable results.

Model Validation

5.3.4.5 The grid properties of the refined model are presented in Appendix 5.2a.

5.3.4.6 A validation process has been conducted by checking the following parameters in the selected observation points and main cross sections channels between the refined model and that Regional Update Model.

Table 5.21 Validation Matrix for Refined Model

Items	Parameters	Locations (Appendix 5.2b)
Cross-sections	Accumulated Flow Salinity Flux	Airport North
		Airport Channel
		BCF South
		Ma Wan
Observation Points	Current Velocity Current Direction	WSR 22c - Tai Ho Wan Inlet (outside)
		WSR 27 - San Tau Beach SSSI
		WSR 41 - Artificial Reef at NE Airport
		WSR 06 - Coral Communities at The Brothers Islands
Map Results	Velocity Vectors	-

5.3.4.7 The validation model result of the refined model is shown in Appendix 5.2b. Modeling results indicate that the refined model generally match with Regional Update Model. This further confirms that the refinement of the model grid did not affect the model.

Model Scenarios

5.3.4.8 Table 5.22 summarizes the scenarios adopted for hydrodynamic modelling in this study.

Table 5.22 Scenarios for Hydrodynamic Modeling for Construction and Operational Phases

Scenario	Hydrodynamic Regime	Coastline / Bathymetry	Purpose
Sceanrio RUM ¡V Reference	Reference Scenario	• Existing coastline	For calibration
Scenario H0 ¡V Base case	Base scenario using refined model	• Existing coastline	For calibration
Scenario H1 ¡V Do-nothing	Without project scenario in ultimate coastline configuration using refined model	• Existing coastline plus HZMB HKBCF^[3], HZMB-HKLR^[3], TM-CLKL^[3], LLP (Siu Ho Wan)^[1], Sunny Bay Lung Kwu Tan and 3RS^[2]; • Existing bathymetery plus KTCB^[4] and MDF^[5].	For operational phase assessment without project scenario
Scenario H2 ¡V Operation Phase	With project scenario in ultimate coastline configuration using refined model	• TCE and Seafront for Road P1 Reclamation; • Existing coastline plus, HZMB HKBCF^[3], HZMB-HKLR^[3], TM-CLKL^[3], LLP (Siu Ho Wan)^[1], Sunny Bay, Lung Kwu Tan and 3RS^[2]; • Existing bathymetery plus KTCB^[4] and MDF^[5].	For operational phase assessment with project scenario
Scenario H3a-c ¡V Construction Phase - 3RS Implementation Schedule in their Approved EIA	With project scenario in different reclamation phases and ultimate coastline configuration using refined model	• TCE and Seafront for Road P1 Reclamation in construction month no. 15, 21 and 31 respectively plus existing coastline, HZMB HKBCF^[3], HZMB-HKLR^[3], TM-CLKL^[3] and 3RS^[2]; • Existing bathymetery plus KTCB^[4] and MDF^[5].	For construction phase assessment in construction month no. 15, 21 and 31 respectively with 3RS implementation schedule in their approved EIA (see Section 5.5.3)
Scenario H3e-f ¡V Construction Phase Sensitivity Scenario for Possible Programme Slippage of 3RS	With project scenario in different reclamation phases and ultimate coastline configuration except 3RS reclamation using refined model	• TCE and Seafront for Road P1 Reclamation in construction month no. 15, 21 and 31 respectively plus existing coastline, HKBCF^[3], HKLR^[3] and TMCLKL^[3] ; • Existing bathymetery plus KTCB^[4] and MDF^[5].	For construction phase assessment in construction month no. 15, 21 and 31 respectively for possible programme slippage of 3RS (see Section 5.5.3)

Notes:

[1] LLP refers to Possible Lantau Logistic Park. The project proponent of LLP has confirmed that there would be no implementation schedule of LLP at this stage. Hence, the construction of LLP has been excluded in the construction phase assessment. For conservative assessment purpose, the LLP reclamation layout has been included in operation phase. Since the reclamation layout of LLP is larger than the Siu Ho Wan reclamation layout under the Study for Cumulative Environmental Impact Assessment Study for the Three Potential Nearshore Reclamation Sites in the Western Waters of Hong Kong, LLP layout has adopted.

[2] Layout of 3RS refers to EIA Report Expansion of Hong Kong International Airport into a Three-Runway System (AEIAR-185/2014)

[3] Approved EIAs for HZMB HKBCF, HZMB HKLR and TM-CLKL

[4] Providing Sufficient Water Depth at Kwai Tsing Container Basin and its Approach Channel (KTCB)

[5] Proposed New Contaminated Mud Marine Disposal Facility at Airport East / East Sha Chau Area (MDF)

5.3.5 Water Quality Modeling

Modeling Parameters

5.3.5.1 The Delft3D-WAQ module was adopted for construction and operational phase water quality modeling. The hydrodynamic outputs from the model were coupled into the water quality module for water quality simulation. The hydrodynamic forcing including averaged fresh water flow, wind, initial conditions and boundary conditions for the dry and wet seasons were applied separately in the corresponding hydrodynamic simulation. Similarly, the pollution loads were applied in the corresponding dry and wet season water quality simulations.

5.3.5.2 The modelling parameters adopted from the approved EIA for HZMB for sedimentation and erosion of SS in construction phase are summarized in Table 5.23

Table 5.23 Parameters for Water Quality Modeling in construction phase

Parameters	Value
Settling velocity	0.5mm/s
Critical stress for deposition	0.2N/m^2
Critical stress for erosion	0.3N/m^2
Minimum depth in which deposition can take place.	0.2m

Model Scenarios

5.3.5.3 Table 5.24 summarizes the scenarios for water quality modeling.

Table 5.24 Scenarios for Water Quality Modeling

Scenario	Description	Hydrodynamic conditions	Purpose
Scenario 01 ¡V Do-nothing	¡P Water quality regime without the project in place in ultimate coastline configuration ¡P Corresponding to Scenario H1 in hydrodynamics	Scenario H1	Operational phase assessment without project scenario
Scenario 02 ¡V Operational Phase	¡P Water quality regime with project in place ¡P Corresponding to Scenario H2 in hydrodynamics	Scenario H2	Operational phase assessment with project scenario
Scenario 03a-c ¡V Construction Phase- 3RS Implementation Schedule in their Approved EIA	¡P Water quality impact during construction phase respectively with 3RS implementation schedule in their approved EIA ¡P Corresponding to Scenario H3a-c in hydrodynamics	Scenario H3 a-c	Construction phase assessment in construction month no. 15, 21 and 31 respectively with 3RS implementation schedule in their approved EIA
Construction Phase Sensitivity Scenario for Possible Programme Slippage of 3RS	¡P Water quality impact during construction phase for possible programme slippage of 3RS ¡P Corresponding to Scenario H3e-f in hydrodynamics	Scenario H3e-f	Construction phase assessment for possible programme slippage of 3RS in construction month no. 15, 21 and 31

5.4 Construction Phase Assessment ¡V Land-based Works

5.4.1 Identification of Pollution Sources

5.4.1.1 Pollution sources from land-based construction are summarized as follows:

¡P General Construction Activities;

¡P Sewage from Workforce;

¡P Construction Works near Tung Chung Stream (including earthworks within CA and CPA zonings);

¡P Bridge Works at Tung Chung Stream;

¡P Construction Work of Sewage Pumping Stations;

¡P Construction Work of Fresh Water and Salt Water Reservoirs;

¡P Construction of Storm water Management Facilities and Polder Scheme;

¡P Groundwater and Runoff for Tunnel Works.

5.4.2 Prediction and Evaluation of Environmental Impacts

5.4.2.1 Construction site runoff would come from all over the works site. The surface runoff might be polluted by:

¡P Runoff and erosion from site surfaces, earth working areas and stockpiles;

¡P Wash water from dust suppression sprays and wheel washing facilities;

¡P Chemicals spillage such as fuel, oil, solvents and lubricants from maintenance of construction machinery and equipment; and

¡P Bentonite Slurries

5.4.2.2 Construction runoff may cause physical, biological and chemical effects. The physical effects include potential blockage of drainage channels and increase of suspended solid levels in the nearby WSRs. Runoff containing significant amounts of concrete and cement-derived material may cause primary chemical effects such as increasing turbidity and discoloration, elevation in pH, and accretion of solids. A number of secondary effects may also result in toxic effects to water biota due to elevated pH values, and reduced decay rates of faecal micro-organisms and photosynthetic rate due to the decreased light penetration.

5.4.2.3 Sewage effluents will be arisen from the sanitary facilities provided for the on-site construction workforce. According to Table T-2 of Guidelines for Estimating Sewage Flows for Sewage Infrastructure Planning, the unit flow is 0.23 m³/day/employed population. The sewage is characterized by high levels of BOD₅, Ammonia and E. coli counts.

5.4.3 Mitigation Measures

General Construction Activities

5.4.3.1 During the construction phase, a temporary drainage system would be implemented to ensure that the surface run-off with high concentration of suspended solid (SS) would not be discharged to Tung Chung Stream. Runoff would need to pass through sedimentation tanks to reduce the concentration of SS.

5.4.3.2 In accordance with the Professional Persons Environmental Consultative Committee Practice Notes on Construction Site Drainage (ProPECC PN 1/94), Environmental Protection Department, 1994, best management practices should be implemented on site as far as practicable. The best practices are detailed below:

¡P At the start of site establishment, perimeter cut-off drains to direct off-site water around the site should be constructed with internal drainage works. Channels, earth bunds or sand bag barriers should be provided on site to direct stormwater to silt removal facilities.

¡P Diversion of natural stormwater should be provided as far as possible. The design of temporary on-site drainage should prevent runoff going through site surface, construction machinery and equipment in order to avoid or minimize polluted runoff. Sedimentation tanks with sufficient capacity, constructed from pre-formed individual cells of approximately 6 to 8 m³ capacities, are recommended as a general mitigation measure which can be used for settling surface runoff prior to disposal. The system capacity shall be flexible and able to handle multiple inputs from a variety of sources and suited to applications where the influent is pumped.

¡P The dikes or embankments for flood protection should be implemented around the boundaries of earthwork areas. Temporary ditches should be provided to facilitate the runoff discharge into an appropriate watercourse, through a silt/sediment trap. The silt/sediment traps should be incorporated in the permanent drainage channels to enhance deposition rates.

¡P The design of efficient silt removal facilities should be based on the guidelines in Appendix A1 of ProPECC PN 1/94. The detailed design of the sand/silt traps should be undertaken by the contractor prior to the commencement of construction.

¡P Construction works should be programmed to minimize surface excavation works during the rainy seasons (April to September). All exposed earth areas should be completed and vegetated as soon as possible after earthworks have been completed. If excavation of soil cannot be avoided during the rainy season, or at any time of year when rainstorms are likely, exposed slope surfaces should be covered by tarpaulin or other means.

¡P All drainage facilities and erosion and sediment control structures should be regularly inspected and maintained to ensure proper and efficient operation at all times and particularly following rainstorms. Deposited silt and grit should be removed regularly and disposed of by spreading evenly over stable, vegetated areas.

¡P If the excavation of trenches in wet periods is necessary, it should be dug and backfilled in short sections wherever practicable. Water pumped out from trenches or foundation excavations should be discharged into storm drains via silt removal facilities.

¡P All open stockpiles of construction materials (for example, aggregates, sand and fill material) should be covered with tarpaulin or similar fabric during rainstorms. Measures should be taken to prevent the washing away of construction materials, soil, silt or debris into any drainage system.

¡P Manholes (including newly constructed ones) should always be adequately covered and temporarily sealed so as to prevent silt, construction materials or debris being washed into the drainage system and storm runoff being directed into foul sewers.

¡P Precautions to be taken at any time of year when rainstorms are likely, actions to be taken when a rainstorm is imminent or forecasted, and actions to be taken during or after rainstorms are summarized in Appendix A2 of ProPECC PN 1/94. Particular attention should be paid to the control of silty surface runoff during storm events.

¡P All vehicles and plant should be cleaned before leaving a construction site to ensure no earth, mud, debris and the like is deposited by them on roads. An adequately designed and sited wheel washing facilities should be provided at every construction site exit where practicable. Wash-water should have sand and silt settled out and removed at least on a weekly basis to ensure the continued efficiency of the process. The section of access road leading to, and exiting from, the wheel-wash bay to the public road should be paved with sufficient backfall toward the wheel-wash bay to prevent vehicle tracking of soil and silty water to public roads and drains.

¡P Oil interceptors should be provided in the drainage system downstream of any oil/fuel pollution sources. The oil interceptors should be emptied and cleaned regularly to prevent the release of oil and grease into the storm water drainage system after accidental spillage. A bypass should be provided for the oil interceptors to prevent flushing during heavy rain.

¡P Construction solid waste, debris and rubbish on site should be collected, handled and disposed of properly to avoid water quality impacts.

¡P All fuel tanks and storage areas should be provided with locks and sited on sealed areas, within bunds of a capacity equal to 110% of the storage capacity of the largest tank to prevent spilled fuel oils from reaching water sensitive receivers nearby.

¡P Regular environmental audit on the construction site should be carried out in order to prevent any malpractices. Notices should be posted at conspicuous locations to remind the workers not to discharge any sewage or wastewater into the water bodies, mangroves and open sea. 

Sewage from Workforce

5.4.3.3 Portable chemical toilets and sewage holding tanks should be provided for handling the construction sewage generated by the workforce. A licensed contractor should be employed to provide appropriate and adequate portable toilets to cater for 0.23 m³/day/employed population and be responsible for appropriate disposal and maintenance. Since temporary sanitary facilities e.g. portable chemical toilets, and sewage holding tank will be provided, no adverse water quality impact is anticipated.

5.4.3.4 Notices should be posted at conspicuous locations to remind the workers not to discharge any sewage or wastewater into the nearby environment during the construction phase of the Project. Regular environmental audit on the construction site should be conducted in order to provide an effective control of any malpractices and achieve continual improvement of environmental performance on site. It is anticipated that sewage generation during the construction phase of the Project would not cause water quality impact after undertaking all required measures.

5.4.3.5 By adopting the best management practices, it is anticipated that the impacts from land-based construction will be reduced to satisfactory levels before discharges. The details of best management practices will be highly dependent to actual site condition and Contractor shall apply for a discharge license under WPCO.

Construction Works near Tung Chung Stream

5.4.3.6 There will be development near Tung Chung Stream. According to the RODP, a 30m buffer zone for the natural sections of Tung Chung Stream and a 20m buffer zone for the major tributary near Ngau Au will be zoned as ¡§CA¡¨, ¡§CPA¡¨, or ¡§OU¡¨ (for polders and the future River Park), except the road crossing locations. Precast structures or other similar approaches will be used to minimize the pollution from construction works to Tung Chung Stream. Some earthworks would also be required within the CA and CPA zonings. Good site management as stipulated in ProPECC PN1/94 will be fully implemented so that the treated runoff will be discharged to public drainage system in compliance with the WPCO. Adverse impact on Tung Chung Stream is not anticipated.

Bridge Works at Tung Chung Stream

5.4.3.7 The local distributors will be extended to connect to existing villages like Ngau Au, Lam Che, Nim Yuen and Mok Ka. Although a few sections of these local distributors (in a form of bridge deck) will have to span over the Tung Chung Stream and its tributaries, only the footings of the bridge deck, which are considerably smaller in size, will be located within the area above high water mark of the buffer zone. Considered that there is only relatively limited works for the footing construction and the area affected would likely be the area above high water mark with relatively less disturbance on ecological habitat. Good site management as stipulated in ProPECC PN1/94 will be fully implemented so that the treated runoff will be discharged to public drainage system in compliance with the WPCO. Adverse impact on Tung Chung Stream is not anticipated.

Construction Work of Sewage Pumping Stations

5.4.3.8 Five new sewage pumping stations (SPSs) and one upgraded SPS are proposed for this project as shown in Figure 2.2 and Figure 2.3. Two proposed SPSs are located in Tung Chung East. Three proposed SPSs and one upgraded SPS are located in Tung Chung West and Tung Chung Valley. A 30m buffer zone for the natural sections of Tung Chung Stream and a 20m buffer zone for the major tributary near Ngau Au will be zoned as ¡§CA¡¨, ¡§CPA¡¨, or ¡§OU¡¨ (for polders and the future River Park), except the road crossing locations to prevent any construction works near river and thus to avoid any direct water quality impact to Tung Chung Stream. Good site management as stipulated in ProPECC PN1/94 will be fully implemented so that the treated runoff will be discharged to public drainage system in compliance with the WPCO. Adverse water quality impact is not anticipated.

Construction Work of Fresh Water and Salt Water Reservoirs

5.4.3.9 Although part of the site had been formed decades ago, construction work for the fresh water and salt water reservoirs would still cause certain water quality impacts. The major construction works will include typical earthwork, concrete works for service reservoir structures, pipeworks and modification work to existing access road. Both cut-and-fill slopes shall be formed for the formation of platform for the service reservoirs construction and for the modification work to existing access road. Good site management as stipulated in ProPECC PN1/94 will be fully implemented so that the treated runoff will be discharged to public drainage system in compliance with the WPCO. Adverse water quality impact is not anticipated.

Construction of Storm Water Management Facilities and Polder Scheme

5.4.3.10 The polder scheme proposed in Tung Chung West as part of the flood protection measures will be generally in form of an earth bund less than approximate 1.5m in height while the stormwater attenuation and treatment ponds will be in form of normal water pond with various depth and planting for sedimentation and water treatment purpose. The works involve earthwork, laying of lining and some water pipe laying works. Suitable landscaping works would also be implemented for the polders and stormwater attenuation and treatment ponds. Good site management as stipulated in ProPECC PN1/94 will be fully implemented so that the treated runoff will be discharged to public drainage system in compliance with the WPCO. Adverse water quality impact is not anticipated.

Groundwater and Runoff for Tunnel Works

5.4.3.11 As discussed in Chapter 2, the proposed railway alignment and new stations are separate projects to be implemented by the future rail operator. However, this EIA has also considered their cumulative impacts based on reasonable assumptions. Tunnel Boring Method (TBM) is considered for the construction of part of the railway tunnel to pass underneath the existing Man Wan Chung bay area and also underneath the hill crests to the northeast of Ma Wan Chung. Ground treatment such as grouting will be carried out prior to bored tunnelling. The intrusion of groundwater during bored tunnelling would therefore be insignificant.

5.4.3.12 Cut-and-Cover method would be adopted for the underpass at Road D1 in Tung Chung East, which involving trench-excavation (i.e. open-cut) followed by in-situ construction of the tunnel structures. Construction methodology using diaphragm wall techniques can minimise the intrusion of groundwater during excavation. It involves excavation of a narrow trench that is kept full of slurry, which exerts hydraulic pressure against the trench walls and acts as a shoring to prevent collapse. Slurry trench excavations can be performed in all types of soil, even below the ground water table.

5.4.3.13 During tunnelling work, rainfall, surface runoff and groundwater seepage pumped out from the tunnel would have high SS content. The situation would be worse during wet seasons. Surface runoff may also be contaminated by bentonite and grouting chemicals that would be required for the tunneling works and diaphragm walls for cut-and-cover tunnel sections. In addition, wastewater from tunnelling works will also contain a high concentration of SS. Good site management as stipulated in ProPECC PN1/94 will be fully implemented by the rail operator so that the treated runoff will be discharged to public drainage system in compliance with the WPCO. Adverse water quality impact is not anticipated.

5.4.4 Residual Impacts

5.4.4.1 No residual land-based water quality impacts are anticipated during construction with the above mitigation measure implemented.

5.5 Construction Phase Assessment ¡V Marine-based Works

5.5.1 Summary of Construction Methodology for Marine Works

Reclamation

5.5.1.1 As discussed in Section 2.7, non-dredged approach for the reclamation in TCE, has been recommended to minimise environmental impacts. However, while dredging work has been preferably avoided, filling work would be inevitable. The actual construction sequences and processes of main reclamation filling shall be further developed by the contractor but the envisaged construction processes of the adopted drained reclamation are summarised below:

1. Installation of the silt curtain;

2. Laying of geotextile and sand blanket over the marine deposit (i.e. over the existing seabed) prior to reclamation filling;

3. Installation of band drains by marine based method to accelerate the consolidation of marine sediment;

4. Construction of seawall to allow at least 200m leading edge before reclamation filling;

5. Underwater filling from sand blanket to +2.50mPD;

6. Land filling from +2.50mPD to formation level; and

7. Surcharging (including construction and removal)

Seawall Construction

5.5.1.2 The details of construction sequences and processes for seawalls shall be further developed by the contractor but the envisaged construction processes of the adopted seawall options are summarized below.

5.5.1.3 The envisaged construction processes for pipe pile type non-dredged seawall supported by stone column are listed as follows. To minimize the water quality impact during the seawall construction, the reclamation work would normally be commenced after the adjacent seawalls (~200m in length) are completed.

1. Installation of the silt curtain;

2. Lay geotextile and deposit rock fill (gravel) blanket;

3. Install stone columns by marine based plant;

4. Install pipe pile structures;

5. Fill inside pipe pile structures;

6. Install corrosion protection system (if necessary) and construct capping beam;

7. Construct sloping berm in front of pipe pile structure (as necessarily).

5.5.2 Identification of Pollution Sources

Stone Column Installation

5.5.2.1 Stone columns will be installed prior to seawall construction and to accelerate the settlement and improve the strength of marine deposits and foundation of temporary reclamation. The stone columns will be installed under seabed levels both inside and outside the seawall and a geotextile layer will be installed to cover the seabed to prevent re-suspension and seabed disturbance. A silt curtain will be deployed to surround the stone column working vessels during installation. In addition to the perimeter silt curtain to the entire marine works area, minor disturbance to water column is anticipated during installation/removal of jet. Good site practice such as regular inspections is considered adequate to minimize the water quality impact.

5.5.2.2 According to the EM&A reports (Mar 2012 to Jun 2014) under the HZMB project, satisfactory performance in terms of water quality was observed during stone column installations. Similar operation will be adopted for this study and adverse water quality impact is therefore not anticipated.

Deep Cement Mixing

5.5.2.3 For ground improvement, a combination of methods including prefabricated vertical drains (PVD), deep cement mixing (DCM), stone columns, steel cells, vertical sand drains and sand compaction piles may be adopted at different locations depending on geotechnical as well as environmental constraints. According to 3RS EIA, overseas application and the local site trial of DCM held in February 2012 has demonstrated that there is no adverse water quality impact associated with this construction method. The findings of the DCM trial concluded that the DCM installation works did not result in any deterioration in marine water quality, and no leakage of contaminants during the course of the DCM trial.

Construction Work of Proposed Marina

5.5.2.4 A marina with an accommodation of 95 berths is proposed at the northern tip of TCE along the waterfront promenade. The worst scenario of SS impact from marine-based construction work which has a much higher SS release rate in filling activities has been considered in Table 5.27d. Floating silt curtain shall be deployed for all marine works to minimize the SS impact to the marine water. Adverse water quality impact is not anticipated.

Marine Traffic

5.5.2.5 During construction phase, marine traffic for the transportation of construction materials for reclamation is anticipated to increase. The induced number of marine vessels during construction phase may impact the marine water quality. The potential water quality impacts include sewage generated by the workers and accidental spillage of chemicals / chemicals waste into the marine environment. The potential impact associated with sewage generated by the workforce can be readily controlled by the provision of adequate sanitary facilities such as portable chemical toilets on the marine vessels. The storage and disposal of chemical waste should follow the guidelines stipulated in the Waste Disposal (Chemical Waste) (General) Regulations. Water quality impacts due to the increase in marine traffic is not anticipated. Besides, overflow of filling materials in the barges or hoppers can cause water pollution during loading or transportation. Good management practice such as limiting the capacity of a barge such that no overflow of filling material can minimise the potential water quality impact.

Reclamation Works of Tung Chung East and Seafront Works for Road P1

5.5.2.6 According to the construction programme, reclamation work of TCE and seafront works for Road P1 will start from 2018 Q1 to 2021 Q4. The reclamation work of Road P1 includes a narrow strip of reclamation of approximately 30m wide for the section connecting TCE to Siu Ho Wan.

Construction Sequence

5.5.2.7 The schematic diagram of key construction phases are presented in Appendix 5.4a. As shown in the diagram, leading seawall of 200m would be formed in advance of reclamation filling.

5.5.2.8 The seawall option mentioned in Section 5.5.1.2 mainly consists of a pipe-pile structure with a sloping berm. Public fill is proposed to be used inside the pipe-pile structures and hence, the filling works is expected to be confined within the pipe-pile structures and adverse water quality impact is not anticipated. The pipe-piles will be interlocking to each other for structural stability. No release of sediment in between the pipe-piles during land reclamation is anticipated. The sediment reduction rate by the pipe-pile seawall would be similar to that by the conventional seawall structure.

5.5.2.9 For the sloping berm in front of the pipe-pile structure, a layer of rock blanket will be placed followed by stone column as the foundation of the berm. The core of the sloping berm will be formed by rock fill. Underlayer in the form of relatively larger grading of rock fill will be placed on top of core as the protection of the core and interface material between the core and the covering rock armour. The sloping berm will be covered up by rock armour as a protection against the wave action and erosion. Since no fine content in the rock fill is expected, SS impact is not anticipated from rock fill.

5.5.2.10 The construction materials proposed for the underwater filling includes a 2m thick sand blanket using sand fill which is followed by public fill up to +2.5mPD. According to the latest construction methodology, the filling rates for public fill and sand blanket for reclamation works are assumed in Table 5.25. The proportion of sand fill and public fill in different construction stage is presented in Appendix 5.4a. An example of calculation of SS release from sand fill and public fill is also given. The working hours for filling activities is assumed from 8:00 to 18:00.

Table 5.25 Estimated filling rates for public fill and sand blanket

Filling Material	Estimated filling volume per quarter of a year	Estimated filling rate m^3 per day^[1]
Public Fill	1,040,000	16,000
Sand blanket	409,370	6,200

Note:

[1] The estimated filling rate is calculated based on 22 working days per month, however 7 working days per week is assumed in the modelling for conservative assessment.

Sediment Loss

5.5.2.11 Table 5.26 summarizes the fine contents and bulk density of filling materials, sand and public fill. The sediment loss rate for public fill and sand blanket is assumed to be 5% of fine content percentage in filling materials (< 63µm) and sediment reduction due to leading seawall is assumed to be 45% from HZMB EIA.

Table 5.26 Filling Material Properties

Filling Material	Fine Contents	Bulk Density
Sand	5%	1,680 kg/m^3
Public Fill	25%	1,900 kg/m^3

Source: EIA ¡V HZMB HKLR

5.5.3 Consideration of Concurrent Projects in Construction Phase

5.5.3.1 The assessment years for the construction phase of Tung Chung Reclamation is from Yr 2018 to Yr 2021. The concurrent projects considered in the construction phase are summarized in Table 5.27a. As most of the marine works for HZMB HKBCF, HZMB HKLR and TM-CLKL will be completed by 2016, the land boundary was included in this study. The bathymetry for KTCB and MDF was included in this study. The sediment release rates for 3RS, Contaminated Mud Pit at East Sha Chau (ESC) CMPs and Tung Chung reclamation (TCE and Road P1) are shown in Appendix 5.4a for comparison. Table 5.27b summarizes the findings. Based on the filling programme, the sediment release rate during construction is shown in Appendix 5.4a. As shown in the appendix, there is no overlapping with the 3RS marine construction activities. However, overlapping with CMP activities is identified. The cumulative impact from CMP has been incorporated in the construction phase assessment.

Table 5.27a Summary of concurrent projects in construction phase

Proposed/Planned Project in the Vicinity	Tentative Implementation Programme	Status & Consideration in This Study
Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities (HZMB HKBCF, being constructed)	Most of the marine works to be completed by 2016	Land boundary was included in this study.
Tuen Mun - Chek Lap Kok Link (TM-CLKL, being constructed)	Most of the marine works to be completed by 2016	Land boundary was included in this study.
Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road (HZMB HKLR, being constructed)	Most of the marine works to be completed by 2016	Land boundary was included in this study.
Expansion of Hong Kong International Airport into a Three-Runway System (3RS)	Construction in marine works for 2015 Q2 to 2017 Q3 To be commissioned by 2023	(i) 3RS in the original EIA programme: Land boundary was included in the study. No SS release from 3RS. (ii) Possible programme slippage of 3RS: SS release from 3RS reclamation was included. No land formed in the 3RS area.
Providing Sufficient Water Depth at Kwai Tsing Container Basin and its Approach Channel (KTCB)	To be commissioned by 2016	EP (EP-426/2011/A) was issued. The bathymetry was included in this study.
Proposed New Contaminated Mud Marine Disposal Facility at HKIA East/East Sha Chau Area (MDF)	To be commissioned by 2016	EP (EP-427/2011/A and EP-312/2008/A) was issued. The SS release and bathymetry was included in this study.

5.5.3.2 According to the latest EM&A schedule of ESC CMPs (Aug 2015) in Appendix 5.4a, there is either backfilling or capping work in ESC CMPs from Yr 2016. The SS release rate in East Sha Chau (ESC) CMPs is therefore calculated based on a dredging/disposal rate of 600 tonne/day. Based on the information from the project proponent of CMPs, capping in South Brothers (SB) CMPs will be completed in Yr 2017 and forecast of works in East Sha Chau (ESC) CMPs are summarized in Table 5.27c. The total SS release rate estimated for ESC CMPs is about 158 tonne/day, taking into account of dredging, backfilling and capping activities, which is smaller than 600 tonne/day adopted in the assessment. The above modelling assumption is on conservative side for prudent sake. In the real situation, the rate of backfilling and capping depends on the other project proponents for dumping of contaminated and clean mud. The modelled worst case cumulative impact is thus very unlikely to be representative of the average daily disposal rates.

Table 5.27b Sediment release rates of public fill and sand fill with concurrent projects

Projects	Duration	Estimated sediment release rate (tonne/day)
Tung Chung Reclamation (TCE and Road P1)	2018 Q1 to 2021 Q4	206 ^[1]
Contaminated Mud Pit at East Sha Chau (CMP)	From 2016 to 2023	600
3RS	2015 Q2 to 2017 Q4	4349^[2]

Notes:

[1] For unmitigated scenario, detailed calculation of sediment release rate is presented in Appendix 5.4a.

[2] Based on the Scenario Yr 2017 in Appendix 8.6 of 3RS EIA.

Table 5.27c Estimated SS release rate (tonne/day) for ESC CMPs *

	2018	2019 Q1	2019 Q2-Q4	2020	2021
Dredging		121
Backfilling	37	18	18	18	18
Capping	37	18	18	12	12
Total	74	158	37	31	31

Note:

* The estimated SS release rate (tonne/day) for ESC CMP is dervided from CEDD information and presented in Appendix 5.4a.

5.5.3.3 According to the sediment release rate diagram in Appendix 5.4a. Table 5.27d summarizes the key construction months selected for water quality modelling.

Table 5.27d Description of selected construction months

Months	Description
15	Commencement of construction. Sediment release rate is highest between 2018 Q3 ¡V Q4. Construction of western seawall is partially completed, which may affect the hydrodynamics in the vicinity.
21	Construction of western seawall is completed and east seawall is partially completed, which may affect the hydrodynamics in the vicinity.
31	Construction of eastern seawall is completed. Sediment release rate is highest between 2020 Q1 ¡V 2021 Q2

5.5.4 Water Quality Modelling Scenarios of SS Impact in Construction Phase

5.5.4.1 The water quality modelling scenarios of SS Impact in Construction Phase are summarized below:

¡P Scenario 03a ¡V Unmitigated Scenario: SS impacts from reclamation work of TCE and seafront works for Road P1 only without mitigation measure.

¡P Scenario 03b ¡V Mitigated Scenario: SS impacts from reclamation work of TCE and seafront works for Road P1 only with mitigation measure.

¡P Scenario 03c - Cumulative SS impacts from Mitigated Scenario of Tung Chung project and concurrent projects if 3RS Implementation Schedule in their Approved EIA.

¡P Scenario 03c +3RS ¡V Sensitivity Scenario for possible programme slippage of 3RS.

5.5.5 Modelling Results of Unmitigated Scenario

5.5.5.1 For Scenario 03a, the predicted maximum elevations in SS at all of the observation points are summarised in Tables 5.28a - Tables 5.28c for construction month numbers 15, 21 and 31. The predicted SS extents are shown in Appendix 5.4b. According to the modelling results of Scenario 03a, it is observed that the plume due to construction is localised and constrained by part of the western seawall and the SS plume would be extended to the eastern side. Exceedance of SS criteria is observed at WSR 22c (Tai Ho Wan Inlet (outside)) in the bottom layer in construction month 15 during wet season. The highest SS elevation (i.e. 4.50 mg/L) is predicted at WSR 22c (Tai Ho Wan Inlet (outside)) in the bottom layer.

5.5.6 Modelling Results of Mitigated Scenario

5.5.6.1 As exceedance of SS levels is observed at WSR 22c (Tai Ho Wan Inlet (outside)) for the unmitigated Scenario 03a, silt curtain is proposed to contain the sediment (i.e. Scenario 03b). The removal efficiency of single floating silt curtain is taken as 45% in accordance with HZMB EIA. The predicted maximum elevations in SS with mitigation measures at observation points are summarised in Tables 5.29a - Tables 5.29c for construction month number 15, 21 and 31 respectively.

5.5.6.2 The predicted SS extents are shown in Appendix 5.4b. Full compliance with SS criteria at identified WSRs has been predicted and adverse water quality impact is therefore not anticipated. Similar to the Scenario 03a result, the highest SS elevation (i.e. 2.48 mg/L) occurs at WSR 22c (Tai Ho Wan Inlet (outside)) in the bottom layer in construction month 15 of wet season. With the implementation of mitigation measures, the SS elevation is within its corresponding criteria level of 2.9 mg/L.

5.5.7 Modelling Results of Mitigated Scenario with Concurrent Projects

3RS Implementation Schedule in their Approved EIA

5.5.7.1 For Scenario 03c, the predicted cumulative maximum elevations in SS at selected observation points due to concurrent projects, including New Contaminated Mud Marine Disposal Facility at Airport East / East Sha Chau Area, are summarised in Tables 5.30a - Tables 5.30c for construction month number 15, 21 and 31 respectively. The predicted SS plume extent is shown in Appendix 5.4b. Exceedance is observed at the following WSRs.

WSR	Season	Layers	Month
WSR04 (Marine Parks at Brothers Islands and Tai Mo To (Dolphin Habitat))	Dry	surface, middle, bottom, depth-averaged	15,21 and 31
	Wet	surface, middle, bottom, depth-averaged	15,21 and 31
WSR 06 (Coral Communities at The Brothers Islands)	Dry	surface, middle, bottom, depth-averaged	15,21 and 31
	Wet	surface, middle, bottom, depth-averaged	15,21 and 31

5.5.7.2 On comparing Scenario 03b (Table 5.29a-c) with Scenario 03c (Table 5.30a-c), the exceedance is dominated by the sediment released from CMP, but not from the proposed project. It should however be noted that the maximum disposal rate in the EP of the CMP either backfilling or capping work have been adopted in this cumulative assessment in order to introduce conservative assumptions in the assessment. Based on the information from the project proponent of CMPs, the estimated total SS release rate estimated for ESC CMPs is about 158 tonne/day (Table 5.27c), taking into account of dredging, backfilling and capping activities, which is smaller than 600 tonne/day adopted in the assessment. According to the conservative assessment, the results reveal that the project contribution would be the highest in Month 31. At WSR 06 (Coral Communities at The Brothers Islands) in Month 31, the cumulative SS concentration is 7.39 mg/L and 4.38 mg/L in dry and wet season, which exceeds the depth-averaged criteria 3.9 mg/L and 2.5 mg/L by 13% and 75% respectively. However, the SS contribution from the present project is 0.00 mg/L and 0.09 mg/L in dry and wet season, which accounts for 0.00% and around 2% of the cumulative contribution respectively. Further analysis has been conducted for the observation point M2, which is at the west boundary of Brothers Islands Marine Park and nearest to ESC CMPs. Results reveal that in Month 31 the cumulative SS concentration is 12.9 mg/L and 6.40 mg/L in dry and wet season respectively, which is higher than that at WSR 06, as it is closer to the ESC CMPs. The SS contribution from the present project is 0.00 mg/L and 0.02 mg/L in dry and wet season at M2, which accounts for 0.00% and 0.3% of the cumulative contribution respectively.

5.5.7.3 In the real situation, the progress of the disposal and capping activities depend on the disposal demand from various marine works projects in Hong Kong. The estimated total SS release rate 158 tonne/day is much lower than the modelled worst case, i.e. 600 tonne/day (26,700 m³/day). The exceedance at WSR04 (Marine Parks at Brothers and Tai Mo To (Dolphin Habitat)) and WSR 06 (Coral Communities at The Brothers Islands) in the modelled worst case cumulative impact is thus very unlikely. However, the CMP construction schedule will be kept review.

Sensitivity Scenario for Possible Programme Slippage of 3RS

5.5.7.4 As shown in Table 5.27b and Appendix 5.4a, programme of the marine work for Tung Chung project and 3RS will not be overlapped based on the approved 3RS EIA. However, given the current circumstance; the 3RS implementation and there may be potential slippage of their construction programme. In order to consider the potential slippage of construction programme of 3RS, a sensitivity scenario was carried out to predict the cumulative SS elevation.

5.5.7.5 According to the 3RS EIA, two construction stages Year 2016 Scenario and Year 2017 Scenario were modeled. Although the sediment release rate in Year 2017 Scenario is higher than that in Year 2016 Scenario, the SS dispersion extent in Year 2016 Scenario is closer to the Project.  Hence, the 3RS configuration in Year 2016 Scenario is adopted, which there would be no land formed in the 3RS area.

5.5.7.6 Besides, under 2016 scenario of 3RS construction, sand blanket and ground improvement for reclamation, water jetting and dredging for diversion of 11kv submarine cable were considered. According to the 3RS EIA, the SS release rates are summarized in Table 5.27e.

Table 5.27e Summary of SS release rates of 3RS construction

Scenario Type	Work Type	Sediment release rate (kg/s)
Reclamation in 2016	sand blanket	0.995
	ground improvement	1.06
Diversion of 11kv submarine cable	water jetting	2.813
	dredging	0.167

5.5.7.7 The predicted SS elevation is summarised in Tables 5.30d - Tables 5.30e for construction month number 15, 21 and 31 respectively. The predicted SS plume extent is shown in Appendix 5.4b. Exceedance is observed at the following WSRs.

WSR	Season	Layers	Month
WSR06 (Coral Communities at The Brothers Islands)	Dry	middle, bottom, depth-averaged	15,21 and 31
	Wet	middle, bottom, depth-averaged	15 and 21
		surface, middle, bottom, depth-averaged	31
WSR 25 (Cooling water intake at Hong Kong International Airport (North))	Dry	middle, bottom	15,21 and 31
	Wet	middle, bottom, depth-averaged	15,21 and 31

5.5.7.8 At WSR04 (Marine Parks at Brothers and Tai Mo To (Dolphin Habitat)), exceeedance is observed in Scenario 03c (Table 5.30a-c), but not in the Scenario 03c with 3RS (Table 5.30d-f). This is because the hydrodynamics is changed under the landform in 3RS reclamation. The extent of SS plumes released from ESC CMPs towards the Brothers Islands are changed. The SS level at WSR04 does not exceed in the sensitivity scenario. This is corresponding to the result that no exceedance in principal criteria (depth-averaged) in 3RS EIA at WSR named E4.

5.5.7.9 While the exceedance at WSR06 (Coral Communities at The Brothers Islands) is due to CMP project, exceedance at WSR 25 (Cooling water intake at Hong Kong International Airport (North)) is contributed by 3RS construction. In the real situation, the rate of backfilling and capping depends on the other project proponents for dumping contaminated mud in backfilling or clean mud in capping, the CMP construction schedule will be kept review.

5.5.7.10 Exccedance at cooling water intake at Hong Kong International Airport (North) (named C7a in 3RS EIA) was also predicted in 3RS EIA. As stated in 3RS EIA, additional mitigation measures such as double silt curtains by 3RS Project Proponent and/or silt screens around the intakes were recommended. With the adoption of these additional mitigation measures, cumulative SS levels due to 3RS construction will be reduced to acceptable levels.

5.5.7.11 The SS conc at the observation point M6 and M10 near the southwest boundary of Sha Chau and Lung Kwu Chau Marine Park (SC & LKC MP) would increase due to the 3RS construction. At the southeast boundary of SC & LKC MP, the SS level at observation point M9 is lower than that of Scenario 03c (i.e. cumulative impact of ESC CMPs if 3RS implementation schedule). This is because the hydrodynamics is changed under the landform in 3RS reclamation and the extent of SS plumes released from ESC CMPs will divert towards the observation point M9. However, the cumulative SS conc at WSR 10 (Sha Chau and Lung Kwu Chau Marine Park) and WSR 42 (Artificial Reef and coral communities at Sha Chau) would comply with the SS criteria.

Table 5.28a Predicted Maximum Suspended Solids (mg/L) Elevations (Unmitigated, Scenario 03a) at Construction Month 15

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.55	0.70	0.75	0.68	0.01	0.01	0.03	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.29	0.38	0.41	0.37	0.00	0.00	0.01	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	0.00	0.00	0.00	0.00	0.00	0.02	0.09	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR07	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR08	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR12	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR18	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	0.00	0.00	0.00	0.00	0.03	0.04	0.04	0.04	10	10	10	10	10	10	10	10	Yes
WSR22a	0.02	0.02	0.03	0.02	0.01	0.02	0.09	0.03	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.24	0.38	1.13	0.41	0.28	1.78	4.50	2.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR25	0.00	0.00	0.00	0.00	0.01	0.02	0.02	0.02	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	0.00	0.00	0.00	0.00	0.01	0.02	0.02	0.02	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.03	0.03	0.03	0.03	0.00	0.00	0.01	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.06	0.07	0.08	0.07	0.01	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	0.00	0.00	0.00	0.00	0.01	0.01	0.03	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.00	0.00	0.00	0.00	0.00	0.00	0.01	0.00	10	10	10	10	10	10	10	10	Yes
WSR45	0.00	0.00	0.01	0.00	0.03	0.05	0.07	0.05	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.01 mg/L for dry season and 0.01-0.04 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be around 0.00 mg/L for both dry season and wet season. The details are presented in Appendix 5.4b.

Table 5.28b Predicted Maximum Suspended Solids (mg/L) Elevations (Unmitigated, Scenario 03a) at Construction Month 21

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.02	0.03	0.03	0.03	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.01	0.01	0.02	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	0.00	0.00	0.00	0.00	0.00	0.03	0.09	0.03	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	0.00	0.00	0.00	0.00	0.00	0.01	0.03	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR07	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR08	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR12	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR18	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	0.00	0.01	0.01	0.01	0.01	0.01	0.01	0.01	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.00	0.00	0.01	0.00	0.00	0.02	0.09	0.03	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	0.00	0.01	0.01	0.01	0.02	0.03	0.05	0.03	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	0.00	0.01	0.01	0.00	0.02	0.03	0.04	0.03	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	0.00	0.01	0.02	0.01	0.01	0.03	0.07	0.03	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.00	0.00	0.00	0.00	0.00	0.00	0.01	0.00	10	10	10	10	10	10	10	10	Yes
WSR45	0.00	0.01	0.02	0.01	0.01	0.02	0.02	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.04 mg/L for dry season and 0.00-0.24 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be around 0.00 mg/L for both dry season and wet season. The details are presented in Appendix 5.4b.

Table 5.28c Predicted Maximum Suspended Solids (mg/L) Elevations (Unmitigated, Scenario 03a) at Construction Month 31

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.04	0.04	0.05	0.04	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.02	0.02	0.02	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	0.01	0.01	0.02	0.01	0.05	0.39	0.83	0.42	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.01	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	0.00	0.01	0.01	0.00	0.02	0.08	0.57	0.17	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR07	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR08	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.01	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.01	700	700	700	700	700	700	700	700	Yes
WSR12	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR18	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	0.00	0.00	0.00	0.00	0.01	0.01	0.00	0.01	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	0.01	0.02	0.03	0.02	0.14	0.16	0.18	0.16	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.00	0.01	0.00	0.00	0.01	0.01	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.01	0.01	0.01	0.01	0.01	0.07	0.25	0.10	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	0.02	0.12	0.17	0.10	0.25	0.47	0.65	0.37	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	0.03	0.06	0.10	0.06	0.24	0.43	0.48	0.37	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	0.03	0.14	0.26	0.13	0.10	0.33	1.02	0.40	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.05	0.09	0.14	0.10	0.01	0.02	0.10	0.03	10	10	10	10	10	10	10	10	Yes
WSR45	0.02	0.05	0.09	0.05	0.14	0.23	0.27	0.21	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.77 mg/L for dry season and 0.04-3.09 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.01 mg/L for dry season and 0.00-0.01 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.29a Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated, Scenario 03b) at Construction Month 15

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.30	0.38	0.41	0.37	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.16	0.21	0.23	0.20	0.00	0.00	0.01	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	0.00	0.00	0.00	0.00	0.00	0.01	0.05	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR07	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR08	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR12	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR18	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	0.00	0.00	0.00	0.00	0.02	0.02	0.02	0.02	10	10	10	10	10	10	10	10	Yes
WSR22a	0.01	0.01	0.02	0.01	0.00	0.01	0.05	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.13	0.21	0.62	0.23	0.16	0.98	2.48	1.11	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.02	0.02	0.02	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.03	0.04	0.04	0.04	0.00	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	0.00	0.00	0.00	0.00	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.00	0.00	0.00	0.00	0.00	0.00	0.01	0.00	10	10	10	10	10	10	10	10	Yes
WSR45	0.00	0.00	0.01	0.00	0.02	0.03	0.04	0.03	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.01 mg/L for dry season and 0.00-0.02 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be around 0.00 mg/L for both dry season and wet season. The details are presented in Appendix 5.4b.

Table 5.29b Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated, Scenario 03b) at Construction Month 21

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.01	0.02	0.02	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	0.00	0.00	0.00	0.00	0.00	0.01	0.05	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	0.00	0.00	0.00	0.00	0.00	0.00	0.01	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR07	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR08	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR12	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR18	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.00	0.00	0.00	0.00	0.00	0.01	0.05	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	0.00	0.01	0.01	0.00	0.01	0.02	0.03	0.02	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	0.00	0.00	0.00	0.00	0.01	0.02	0.02	0.01	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	0.00	0.01	0.01	0.01	0.00	0.02	0.04	0.02	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR45	0.00	0.01	0.01	0.01	0.01	0.01	0.01	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Notes

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.02 mg/L for dry season and 0.00-0.13 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be around 0.00 mg/L for both dry season and wet season. The details are presented in Appendix 5.4b.

Table 5.29c Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated, Scenario 03b) at Construction Month 31

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.02	0.02	0.03	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	0.00	0.01	0.01	0.01	0.03	0.22	0.45	0.23	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	0.00	0.00	0.00	0.00	0.01	0.04	0.31	0.09	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR07	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR08	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.00	0.00	0.00	0.00	0.00	0.00	0.01	0.00	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	700	700	700	700	700	700	700	700	Yes
WSR12	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	10	10	10	10	10	10	10	10	Yes
WSR18	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	0.01	0.01	0.01	0.01	0.08	0.09	0.10	0.09	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.00	0.00	0.00	0.00	0.00	0.04	0.14	0.05	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	0.01	0.07	0.09	0.05	0.14	0.26	0.36	0.20	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	0.02	0.03	0.05	0.03	0.13	0.24	0.27	0.20	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	0.02	0.08	0.14	0.07	0.05	0.18	0.55	0.22	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.03	0.05	0.08	0.05	0.01	0.01	0.05	0.02	10	10	10	10	10	10	10	10	Yes
WSR45	0.01	0.03	0.05	0.03	0.08	0.13	0.15	0.12	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Notes:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.43 mg/L for dry season and 0.02-1.70 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be around 0.00 mg/L for dry season and 0.00-0.01 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.30a Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated and Concurrent Project, Scenario 03c) at Construction Month 15

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.30	0.39	0.41	0.37	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.16	0.21	0.23	0.20	0.00	0.00	0.01	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	3.05	6.30	7.22	5.74	2.71	3.54	3.58	2.82	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR05a	0.92	1.40	1.42	1.19	0.68	0.84	1.29	0.82	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.22	0.26	0.60	0.29	0.44	0.68	0.89	0.64	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	3.69	8.31	10.54	7.35	3.09	4.67	6.07	4.38	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR07	0.70	1.04	1.41	0.94	0.52	0.83	1.12	0.83	700	700	700	700	700	700	700	700	Yes
WSR08	0.66	1.26	1.41	1.15	0.41	0.90	1.19	0.77	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.61	2.59	4.35	2.20	0.17	1.36	3.34	1.51	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.76	1.24	1.48	1.15	0.81	1.17	1.41	1.04	700	700	700	700	700	700	700	700	Yes
WSR12	0.19	0.34	0.51	0.32	0.27	0.62	0.73	0.56	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.47	0.66	0.80	0.60	0.26	0.62	0.85	0.58	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.01	0.00	0.01	0.01	0.03	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.08	0.20	0.24	0.16	0.04	0.11	0.21	0.11	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.01	0.02	0.11	0.04	0.02	0.02	0.08	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.96	1.17	1.34	1.07	0.50	0.75	1.05	0.67	10	10	10	10	10	10	10	10	Yes
WSR18	0.95	1.32	1.40	1.19	0.79	0.94	1.07	0.86	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.22	0.38	0.46	0.35	0.29	0.41	0.42	0.38	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	1.46	1.59	1.61	1.56	1.24	1.39	1.41	1.33	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	1.34	2.20	2.48	2.03	1.40	1.48	2.15	1.48	10	10	10	10	10	10	10	10	Yes
WSR22a	0.02	0.04	0.05	0.03	0.10	0.22	0.21	0.17	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.13	0.21	0.62	0.23	0.17	0.99	2.51	1.13	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	1.40	1.90	2.12	1.59	1.84	2.26	3.13	2.18	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	1.27	2.70	6.14	2.96	2.01	2.53	2.64	2.44	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.02	0.02	0.02	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.03	0.04	0.04	0.04	0.00	0.01	0.01	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.01	0.01	0.01	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	2.54	3.71	4.00	3.13	1.96	3.45	6.17	2.17	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.72	0.82	0.91	0.82	0.19	0.34	0.78	0.32	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.65	0.91	0.94	0.72	0.77	0.87	1.63	0.83	10	10	10	10	10	10	10	10	Yes
WSR45	1.64	2.25	2.65	2.09	1.60	1.53	2.16	1.43	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Notes:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 1.34-12.95 mg/L for dry season and 1.38-6.40 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 0.67-4.92 mg/L for dry season and 0.26-3.42 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.30b Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated and Concurrent Project, Scenario 03c) at Construction Month 21

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.01	0.02	0.02	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	3.03	6.22	7.24	5.70	2.75	3.36	3.27	2.64	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR05a	0.93	1.43	1.42	1.20	0.72	0.83	1.28	0.82	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.22	0.25	0.57	0.28	0.43	0.67	0.89	0.64	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	3.85	8.41	10.69	7.48	3.17	4.29	5.36	4.08	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR07	0.71	1.03	1.44	0.94	0.52	0.83	1.11	0.83	700	700	700	700	700	700	700	700	Yes
WSR08	0.66	1.27	1.43	1.17	0.40	0.88	1.23	0.76	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.61	2.59	4.27	2.20	0.18	1.44	3.20	1.48	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.78	1.26	1.50	1.17	0.78	1.19	1.38	1.04	700	700	700	700	700	700	700	700	Yes
WSR12	0.19	0.34	0.51	0.31	0.26	0.61	0.74	0.55	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.48	0.66	0.80	0.60	0.26	0.61	0.84	0.57	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.01	0.00	0.01	0.01	0.03	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.08	0.19	0.24	0.16	0.04	0.11	0.21	0.11	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.01	0.02	0.11	0.04	0.02	0.02	0.08	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.96	1.17	1.34	1.07	0.52	0.73	1.06	0.67	10	10	10	10	10	10	10	10	Yes
WSR18	0.95	1.32	1.40	1.19	0.79	0.96	1.09	0.88	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.22	0.37	0.46	0.35	0.28	0.41	0.42	0.37	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	1.47	1.59	1.62	1.56	1.23	1.37	1.40	1.32	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	1.37	2.20	2.50	2.04	1.40	1.48	2.19	1.48	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.01	0.01	0.01	0.04	0.07	0.07	0.06	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.02	0.03	0.03	0.03	0.14	0.57	0.61	0.46	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	1.42	1.72	1.94	1.43	1.77	2.26	3.20	2.16	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	1.27	2.51	6.03	2.87	1.97	2.47	2.58	2.38	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.01	0.01	0.01	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	2.57	3.66	3.95	3.09	1.97	3.75	5.95	2.11	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.72	0.83	0.92	0.83	0.19	0.34	0.82	0.31	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.63	0.88	0.91	0.69	0.77	0.86	1.65	0.82	10	10	10	10	10	10	10	10	Yes
WSR45	1.66	2.26	2.66	2.10	1.58	1.45	2.19	1.43	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 1.33-13.16 mg/L for dry season and 1.43-6.33 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 0.66-4.94 mg/L for dry season and 0.25-3.46 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.30c Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated and Concurrent Project, Scenario 03c) at Construction Month 31

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.02	0.02	0.03	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	3.20	6.26	7.20	5.77	2.79	3.46	3.25	2.74	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR05a	0.92	1.42	1.41	1.20	0.74	0.84	1.28	0.84	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.22	0.26	0.59	0.29	0.43	0.67	0.90	0.65	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	3.74	8.36	10.53	7.39	3.19	4.69	6.15	4.38	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR07	0.70	1.03	1.44	0.94	0.51	0.81	1.12	0.82	700	700	700	700	700	700	700	700	Yes
WSR08	0.66	1.26	1.42	1.16	0.40	0.87	1.19	0.75	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	0.62	2.58	4.39	2.19	0.18	1.40	3.21	1.46	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.76	1.24	1.48	1.15	0.77	1.18	1.38	1.04	700	700	700	700	700	700	700	700	Yes
WSR12	0.19	0.34	0.50	0.32	0.26	0.61	0.74	0.54	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.47	0.65	0.80	0.59	0.26	0.61	0.85	0.57	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.01	0.00	0.01	0.01	0.03	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.08	0.20	0.24	0.16	0.04	0.12	0.21	0.11	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.01	0.02	0.11	0.04	0.02	0.02	0.09	0.02	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	0.95	1.17	1.34	1.06	0.53	0.75	1.04	0.67	10	10	10	10	10	10	10	10	Yes
WSR18	0.95	1.32	1.41	1.19	0.79	0.95	1.08	0.87	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.22	0.38	0.46	0.35	0.29	0.41	0.42	0.38	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	1.47	1.59	1.62	1.56	1.24	1.39	1.40	1.33	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	1.38	2.20	2.49	2.04	1.41	1.49	2.17	1.49	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.01	0.01	0.00	0.03	0.06	0.05	0.05	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.02	0.03	0.03	0.03	0.14	0.51	0.56	0.43	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	1.44	1.79	1.99	1.50	1.86	2.45	3.11	2.23	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR26	1.27	2.65	6.13	2.95	2.25	2.71	2.84	2.61	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.00	0.00	0.00	0.00	0.00	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.00	0.01	0.01	0.01	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	2.56	3.54	3.82	2.99	1.98	3.55	5.93	2.19	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	0.72	0.83	0.92	0.82	0.20	0.34	0.86	0.32	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	0.65	0.89	0.86	0.66	0.74	0.83	1.72	0.78	10	10	10	10	10	10	10	10	Yes
WSR45	1.67	2.26	2.65	2.10	1.58	1.52	2.21	1.43	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 1.36-12.94 mg/L for dry season and 1.42-6.40 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 0.66-4.93 mg/L for dry season and 0.25-3.44 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.30d Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated and Concurrent Project, Scenario 03c and 3RS) at Construction Month 15

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.45	0.57	0.61	0.55	0.00	0.02	0.04	0.02	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.25	0.32	0.35	0.31	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.01	0.02	0.02	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	1.99	2.59	2.70	2.29	1.78	2.34	2.29	1.90	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	1.04	1.45	1.51	1.25	0.67	1.06	1.61	0.99	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.22	0.22	0.54	0.24	0.54	0.85	1.09	0.81	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	2.08	6.04	7.76	5.41	2.17	4.20	4.65	3.67	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR07	0.80	1.14	1.53	1.03	0.57	0.93	1.32	0.94	700	700	700	700	700	700	700	700	Yes
WSR08	0.73	1.47	1.62	1.32	0.33	0.92	1.37	0.82	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	1.34	3.80	5.45	3.09	0.59	2.48	6.08	2.92	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.86	1.35	1.65	1.25	0.88	1.52	1.69	1.31	700	700	700	700	700	700	700	700	Yes
WSR12	0.20	0.40	0.53	0.32	0.34	0.80	0.94	0.72	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.53	0.70	0.85	0.65	0.28	0.77	1.07	0.74	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.01	0.01	0.04	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.09	0.24	0.28	0.18	0.07	0.13	0.25	0.12	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.01	0.03	0.13	0.05	0.03	0.03	0.11	0.03	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	1.04	1.24	1.42	1.17	0.69	0.95	1.32	0.86	10	10	10	10	10	10	10	10	Yes
WSR18	1.01	1.32	1.41	1.21	0.97	1.09	1.25	1.02	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.30	0.43	0.52	0.41	0.30	0.43	0.45	0.40	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	1.61	1.72	1.74	1.69	0.98	1.20	1.26	1.13	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	1.24	1.81	2.05	1.63	0.71	1.17	1.85	1.12	10	10	10	10	10	10	10	10	Yes
WSR22a	0.01	0.02	0.03	0.02	0.08	0.16	0.20	0.11	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.01	0.01	0.01	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.12	0.19	0.40	0.23	0.14	0.64	1.59	0.75	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	2.35	4.77	7.51	4.17	1.86	4.02	10.20	3.94	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	No
WSR27	0.04	0.05	0.05	0.05	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.11	0.14	0.15	0.14	0.02	0.05	0.08	0.04	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.02	0.04	0.04	0.03	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.01	0.03	0.04	0.02	0.08	0.18	0.37	0.19	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.06	0.10	0.10	0.09	0.18	0.38	0.68	0.31	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.07	0.10	0.11	0.09	0.24	0.28	0.26	0.27	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.01	0.01	0.01	0.03	0.05	0.04	0.04	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.06	0.06	0.06	0.06	0.06	0.07	0.06	0.06	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	2.25	2.29	3.44	2.09	2.05	2.35	4.02	2.07	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	2.39	2.81	3.19	2.81	1.09	2.66	3.44	2.23	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	2.02	2.52	2.49	2.40	1.39	1.66	1.87	1.65	10	10	10	10	10	10	10	10	Yes
WSR45	1.13	1.92	2.18	1.76	0.89	1.18	1.75	1.08	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.75-13.15 mg/L for dry season and 0.96-7.08 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 2.03-4.86 mg/L for dry season and 1.26-3.02- mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.30e Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated and Concurrent Project, Scenario 03c and 3RS) at Construction Month 21

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.02	0.03	0.03	0.03	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.01	0.01	0.02	0.01	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	1.94	2.54	2.64	2.25	1.84	2.24	2.12	1.83	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	1.03	1.47	1.51	1.26	0.68	1.11	1.58	0.98	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.22	0.22	0.54	0.24	0.53	0.85	1.08	0.81	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	2.09	6.02	7.78	5.40	2.29	4.04	4.85	3.73	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR07	0.79	1.13	1.56	1.02	0.58	0.91	1.29	0.92	700	700	700	700	700	700	700	700	Yes
WSR08	0.74	1.49	1.65	1.34	0.35	0.92	1.40	0.81	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	1.33	3.74	5.38	3.05	0.54	2.51	6.28	2.93	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.85	1.34	1.65	1.24	0.86	1.48	1.69	1.29	700	700	700	700	700	700	700	700	Yes
WSR12	0.21	0.40	0.54	0.33	0.32	0.78	0.92	0.70	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.54	0.71	0.86	0.66	0.27	0.75	1.05	0.71	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.01	0.01	0.04	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.09	0.23	0.28	0.18	0.06	0.14	0.25	0.13	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.01	0.03	0.13	0.05	0.03	0.03	0.11	0.03	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	1.05	1.24	1.42	1.18	0.69	0.94	1.32	0.85	10	10	10	10	10	10	10	10	Yes
WSR18	1.01	1.32	1.40	1.21	0.97	1.09	1.25	1.02	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.30	0.43	0.52	0.41	0.30	0.44	0.45	0.40	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	1.60	1.71	1.73	1.68	0.98	1.21	1.27	1.13	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	1.25	1.81	2.07	1.63	0.70	1.16	1.85	1.12	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.00	0.00	0.00	0.03	0.06	0.10	0.05	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.01	0.01	0.01	0.01	0.10	0.39	0.44	0.32	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	2.36	4.77	7.46	4.16	1.91	3.95	10.79	3.71	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	No
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.01	0.01	0.00	0.02	0.04	0.06	0.03	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.01	0.03	0.03	0.03	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.01	0.03	0.03	0.02	0.09	0.18	0.36	0.18	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.06	0.10	0.10	0.09	0.18	0.38	0.66	0.31	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.07	0.10	0.11	0.09	0.24	0.29	0.27	0.27	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.01	0.01	0.01	0.03	0.05	0.04	0.04	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.05	0.06	0.06	0.06	0.06	0.07	0.06	0.06	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	2.24	2.33	3.41	2.10	2.14	2.41	4.63	2.11	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	2.35	2.76	3.14	2.76	0.99	2.69	3.51	2.27	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	2.05	2.57	2.58	2.45	1.37	1.65	1.87	1.64	10	10	10	10	10	10	10	10	Yes
WSR45	1.13	1.93	2.17	1.77	0.84	1.20	1.72	1.07	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.72-12.98 mg/L for dry season and 1.00-7.08 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 1.99-4.88 mg/L for dry season and 1.26-2.97 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.30f Predicted Maximum Suspended Solids (mg/L) Elevations (Mitigated and Concurrent Project, Scenario 03c and 3RS) at Construction Month 31

WSR	Modeling Result								Suspended Solids Criteria (mg/L)
	Dry Season				Wet Season				Dry Season				Wet Season				Compliance to Suspended Solids Criteria (mg/L)
	S	M	B	DA	S	M	B	DA	S	M	B	DA	S	M	B	DA
WSR01	0.03	0.03	0.04	0.03	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR02	0.01	0.02	0.02	0.02	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR03	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR04	1.95	2.53	2.66	2.24	1.77	2.17	2.14	1.79	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR05a	1.03	1.46	1.50	1.26	0.67	1.05	1.62	1.00	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR05b	0.22	0.22	0.54	0.24	0.54	0.86	1.09	0.82	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR06	2.09	6.09	7.78	5.43	2.42	3.96	5.45	3.80	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	No
WSR07	0.79	1.13	1.55	1.02	0.58	0.90	1.32	0.92	700	700	700	700	700	700	700	700	Yes
WSR08	0.73	1.47	1.62	1.32	0.33	0.92	1.31	0.83	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR10	1.33	3.89	5.41	3.16	0.52	2.47	6.25	2.88	4.2	5.7	9.7	6.2	2.9	4	10.9	6.1	Yes
WSR11	0.86	1.35	1.65	1.25	0.87	1.50	1.69	1.30	700	700	700	700	700	700	700	700	Yes
WSR12	0.20	0.40	0.53	0.32	0.32	0.80	0.93	0.71	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	Yes
WSR13	0.53	0.71	0.87	0.66	0.28	0.77	1.05	0.71	10	10	10	10	10	10	10	10	Yes
WSR14	0.00	0.00	0.00	0.00	0.01	0.01	0.04	0.01	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR15	0.09	0.23	0.28	0.18	0.06	0.14	0.25	0.13	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR16	0.01	0.03	0.13	0.05	0.03	0.03	0.11	0.03	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR17	1.05	1.23	1.41	1.18	0.69	0.91	1.34	0.84	10	10	10	10	10	10	10	10	Yes
WSR18	1.00	1.31	1.40	1.20	0.97	1.09	1.26	1.02	3.3	4.8	5.1	4.4	2	3.3	5.8	3.6	Yes
WSR19	0.30	0.43	0.52	0.41	0.30	0.44	0.45	0.40	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR20	1.60	1.71	1.73	1.68	0.98	1.22	1.26	1.14	2.4	3.3	5.2	3.7	1.7	2.7	5.1	2.9	Yes
WSR21	1.25	1.81	2.07	1.64	0.74	1.18	1.86	1.13	10	10	10	10	10	10	10	10	Yes
WSR22a	0.00	0.00	0.00	0.00	0.03	0.05	0.08	0.04	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22b	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR22c	0.01	0.01	0.01	0.01	0.09	0.37	0.41	0.30	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes
WSR25	2.37	4.84	7.77	4.26	1.90	3.99	11.34	3.67	3.3	3.9	6.3	4.3	2.4	3	5.1	3.5	No
WSR27	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR28	0.00	0.00	0.00	0.00	0.01	0.03	0.05	0.02	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR29	0.00	0.00	0.00	0.00	0.01	0.02	0.03	0.02	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR30	0.01	0.02	0.03	0.02	0.09	0.18	0.37	0.18	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR31	0.06	0.10	0.10	0.08	0.18	0.38	0.69	0.32	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR32	0.00	0.00	0.00	0.00	0.00	0.01	0.02	0.01	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR33	0.07	0.10	0.10	0.09	0.24	0.30	0.27	0.28	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR34	0.00	0.01	0.01	0.01	0.03	0.05	0.04	0.04	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR35	0.05	0.06	0.06	0.06	0.06	0.07	0.06	0.06	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR41	2.28	2.23	3.27	1.99	2.15	2.37	4.68	2.12	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR42	2.39	2.80	3.18	2.80	1.12	2.64	3.46	2.24	6.9	7.9	12.7	9	3	4.9	9.4	5.6	Yes
WSR44	2.03	2.56	2.53	2.42	1.39	1.70	1.88	1.67	10	10	10	10	10	10	10	10	Yes
WSR45	1.13	1.93	2.18	1.76	0.88	1.24	1.76	1.10	2.8	3	5.5	3.9	2.4	2.6	2.9	2.5	Yes

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged;

[2] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum suspended solids elevations in depth averaged would be 0.74-13.19 mg/L for dry season and 1.17-7.12 mg/L for wet season. The details are presented in Appendix 5.4b.

[3] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 2.00-4.85 mg/L for dry season and 1.28-3.17 mg/L for wet season. The details are presented in Appendix 5.4b.

Sedimentation Rate

5.5.7.12 The predicted maximum daily sedimentation rates at all the sensitive receivers are summarised in Table 5.31a-c. The predicted maximum daily sedimentation rates at the affected WSRs with 3RS are summarised in Table 5.31d. According to the modelling results, it is clear that the predicted daily sedimentation rates due to construction under the unmitigated scenario (Scenario 03a), mitigated scenario (Scenario 03b), cumulative impact scenario (Scenario 03c) and sensitivity scenario with 3RS at all WSRs are well within the criterion of 200 g/m²/day. At observation point M2, which would be nearest to ESC CMPs, the predicted maximum daily sedimentation rates in the cumulative impact scenario (Scenario 03c) and sensitivity scenario with 3RS are 112 and 107 g/m²/day respectively, which are within the criterion of 200 g/m²/day. Hence, adverse water quality impact due to sedimentation is not anticipated.

Table 5.31a Predicted Maximum Sedimentation Rates (Unmitigated, Scenario 03a)

Water Sensitive Receivers	Predicted Maximum Sedimentation Rates (g/m2/day)
	Dry Season			Wet Season
	M15	M21	M31	M15	M21	M31
WSR01	6.48	0.26	0.41	0.24	0.01	0.01
WSR02	3.56	0.13	0.20	0.10	0.00	0.00
WSR03	0.11	0.00	0.00	0.02	0.00	0.00
WSR04	0.00	0.00	0.20	0.48	0.65	6.70
WSR05a	0.00	0.00	0.01	0.01	0.01	0.06
WSR05b	0.00	0.00	0.00	0.00	0.00	0.03
WSR06	0.00	0.01	0.03	0.12	0.23	4.95
WSR07	0.00	0.00	0.00	0.00	0.00	0.03
WSR08	0.00	0.00	0.00	0.00	0.00	0.03
WSR10	0.00	0.00	0.01	0.00	0.00	0.08
WSR11	0.00	0.00	0.01	0.01	0.01	0.08
WSR12	0.00	0.00	0.00	0.00	0.00	0.03
WSR13	0.00	0.00	0.00	0.00	0.00	0.03
WSR14	0.00	0.00	0.00	0.00	0.00	0.00
WSR15	0.00	0.00	0.00	0.00	0.00	0.01
WSR16	0.00	0.00	0.00	0.00	0.00	0.00
WSR17	0.00	0.00	0.00	0.01	0.00	0.02
WSR18	0.00	0.00	0.00	0.00	0.00	0.01
WSR19	0.00	0.00	0.00	0.00	0.00	0.01
WSR20	0.00	0.00	0.01	0.02	0.01	0.04
WSR21	0.02	0.02	0.11	0.19	0.09	1.08
WSR22a	0.27	0.02	0.05	0.80	0.02	0.09
WSR22b	0.02	0.00	0.00	0.01	0.00	0.01
WSR22c	7.43	0.07	0.07	32.35	0.78	2.10
WSR25	0.01	0.09	1.06	0.12	0.26	3.88
WSR26	0.01	0.06	0.74	0.13	0.23	2.92
WSR27	0.27	0.01	0.01	0.06	0.00	0.00
WSR28	0.67	0.01	0.02	0.10	0.00	0.00
WSR29	0.01	0.00	0.00	0.00	0.00	0.00
WSR30	0.00	0.00	0.00	0.00	0.00	0.00
WSR31	0.00	0.00	0.00	0.00	0.00	0.00
WSR32	0.00	0.00	0.00	0.00	0.00	0.00
WSR33	0.00	0.00	0.00	0.00	0.00	0.00
WSR34	0.00	0.00	0.00	0.00	0.00	0.00
WSR35	0.00	0.00	0.00	0.00	0.00	0.00
WSR41	0.01	0.11	1.33	0.18	0.38	5.31
WSR42	0.00	0.00	0.00	0.00	0.00	0.01
WSR44	0.01	0.02	1.18	0.07	0.06	0.78
WSR45	0.04	0.04	0.22	0.16	0.10	1.10

[1] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum sedimentation rates would be 0.00-10.98 mg/L for dry season and 0.02-27.14 mg/L for wet season. The details are presented in Appendix 5.4b.

[2] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.07 mg/L for dry season and 0.00-0.32 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.31b Predicted Maximum Sedimentation Rates (Mitigated, Scenario 03b)

Water Sensitive Receivers	Predicted Maximum Sedimentation Rates (g/m2/day)
	Dry Season			Wet Season
	M15	M21	M31	M15	M21	M31
WSR01	3.53	0.14	0.23	0.13	0.00	0.00
WSR02	1.97	0.07	0.11	0.05	0.00	0.00
WSR03	0.06	0.00	0.00	0.01	0.00	0.00
WSR04	0.00	0.00	0.11	0.25	0.35	3.70
WSR05a	0.00	0.00	0.00	0.00	0.00	0.03
WSR05b	0.00	0.00	0.00	0.00	0.00	0.02
WSR06	0.00	0.00	0.01	0.07	0.13	2.64
WSR07	0.00	0.00	0.00	0.00	0.00	0.02
WSR08	0.00	0.00	0.00	0.00	0.00	0.02
WSR10	0.00	0.00	0.00	0.00	0.00	0.04
WSR11	0.00	0.00	0.00	0.01	0.00	0.04
WSR12	0.00	0.00	0.00	0.00	0.00	0.02
WSR13	0.00	0.00	0.00	0.00	0.00	0.02
WSR14	0.00	0.00	0.00	0.00	0.00	0.00
WSR15	0.00	0.00	0.00	0.00	0.00	0.01
WSR16	0.00	0.00	0.00	0.00	0.00	0.00
WSR17	0.00	0.00	0.00	0.00	0.00	0.01
WSR18	0.00	0.00	0.00	0.00	0.00	0.01
WSR19	0.00	0.00	0.00	0.00	0.00	0.00
WSR20	0.00	0.00	0.00	0.01	0.00	0.02
WSR21	0.01	0.01	0.06	0.10	0.05	0.59
WSR22a	0.15	0.01	0.02	0.43	0.01	0.05
WSR22b	0.01	0.00	0.00	0.01	0.00	0.00
WSR22c	4.10	0.04	0.04	17.79	0.43	1.17
WSR25	0.00	0.05	0.60	0.06	0.13	2.03
WSR26	0.00	0.03	0.40	0.07	0.12	1.60
WSR27	0.15	0.00	0.01	0.03	0.00	0.00
WSR28	0.37	0.01	0.01	0.06	0.00	0.00
WSR29	0.01	0.00	0.00	0.00	0.00	0.00
WSR30	0.00	0.00	0.00	0.00	0.00	0.00
WSR31	0.00	0.00	0.00	0.00	0.00	0.00
WSR32	0.00	0.00	0.00	0.00	0.00	0.00
WSR33	0.00	0.00	0.00	0.00	0.00	0.00
WSR34	0.00	0.00	0.00	0.00	0.00	0.00
WSR35	0.00	0.00	0.00	0.00	0.00	0.00
WSR41	0.01	0.06	0.73	0.10	0.21	2.97
WSR42	0.00	0.00	0.00	0.00	0.00	0.01
WSR44	0.00	0.01	0.65	0.04	0.03	0.43
WSR45	0.03	0.02	0.12	0.09	0.06	0.61

[1] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum sedimentation rates would be 0.00-5.96 mg/L for dry season and 0.01-15.00 mg/L for wet season. The details are presented in Appendix 5.4b.

[2] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 0.00-0.04 mg/L for dry season and 0.00-0.18 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.31c Predicted Maximum Sedimentation Rates (Mitigated and Concurrent Project, Scenario 03c)

Water Sensitive Receivers	Predicted Maximum Sedimentation Rates (g/m2/day)
	Dry Season			Wet Season
	M15	M21	M31	M15	M21	M31
WSR01	3.53	0.14	0.23	0.13	0.00	0.00
WSR02	1.96	0.07	0.11	0.05	0.00	0.00
WSR03	0.06	0.00	0.00	0.01	0.00	0.00
WSR04	55.44	55.07	55.73	20.75	20.33	20.03
WSR05a	12.05	12.07	12.01	10.11	10.02	9.87
WSR05b	5.00	4.75	4.95	7.36	7.26	7.42
WSR06	77.84	79.92	79.31	45.25	41.96	45.64
WSR07	9.69	9.73	9.63	7.19	7.27	7.27
WSR08	11.12	11.22	11.16	10.28	10.49	10.09
WSR10	34.24	33.50	34.30	22.78	22.49	21.41
WSR11	12.71	12.87	12.71	11.96	11.74	11.71
WSR12	4.13	4.13	4.13	6.16	6.10	6.09
WSR13	6.12	6.14	6.05	5.16	5.10	5.32
WSR14	0.06	0.06	0.06	0.23	0.21	0.22
WSR15	1.88	1.86	1.88	1.69	1.68	1.68
WSR16	0.92	0.92	0.91	0.71	0.70	0.73
WSR17	10.48	10.60	10.50	8.37	8.57	8.61
WSR18	6.94	6.83	6.92	5.65	5.71	5.63
WSR19	3.26	3.25	3.29	3.44	3.42	3.44
WSR20	12.42	12.30	12.32	11.89	11.90	11.89
WSR21	13.48	13.86	13.73	13.71	13.64	13.58
WSR22a	0.41	0.08	0.06	1.79	0.61	0.44
WSR22b	0.01	0.00	0.00	0.08	0.03	0.02
WSR22c	4.10	0.29	0.25	17.22	5.18	4.76
WSR25	18.26	16.44	17.10	24.71	25.31	24.52
WSR26	51.08	50.14	50.85	21.51	21.23	22.93
WSR27	0.15	0.00	0.01	0.03	0.00	0.00
WSR28	0.37	0.01	0.01	0.06	0.01	0.01
WSR29	0.01	0.00	0.00	0.01	0.01	0.01
WSR30	0.02	0.02	0.01	0.07	0.08	0.08
WSR31	0.05	0.04	0.05	0.19	0.19	0.19
WSR32	0.00	0.00	0.00	0.01	0.01	0.01
WSR33	0.02	0.02	0.02	0.06	0.06	0.06
WSR34	0.00	0.00	0.00	0.02	0.02	0.02
WSR35	0.02	0.02	0.02	0.03	0.03	0.03
WSR41	21.50	20.14	21.27	51.53	49.69	49.43
WSR42	5.62	5.40	5.56	6.00	6.32	6.59
WSR44	7.64	7.40	6.96	8.48	9.05	8.78
WSR45	13.16	13.29	13.26	14.11	13.93	14.17

[1] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum sedimentation rates would be 11.94-111.74 mg/L for dry season and 13.16-73.91 mg/L for wet season. The details are presented in Appendix 5.4b.

[2] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 4.76-51.93 mg/L for dry season and 1.99-44.46 mg/L for wet season. The details are presented in Appendix 5.4b.

Table 5.31d Predicted Maximum Sedimentation Rates (Mitigated and Concurrent Project, Scenario 03c and 3RS)

Water Sensitive Receivers	Predicted Maximum Sedimentation Rates (g/m2/day)
	Dry Season			Wet Season
	M15	M21	M31	M15	M21	M31
WSR01	5.17	0.25	0.31	0.35	0.01	0.01
WSR02	2.99	0.13	0.16	0.19	0.01	0.01
WSR03	0.15	0.00	0.00	0.03	0.00	0.00
WSR04	17.49	17.24	17.84	12.24	12.83	12.96
WSR05a	12.82	12.82	12.76	13.15	12.77	13.16
WSR05b	4.53	4.58	4.53	9.06	8.97	9.17
WSR06	51.36	54.69	50.30	34.72	38.11	39.05
WSR07	10.60	10.57	10.53	7.65	7.53	7.44
WSR08	12.93	13.13	12.97	11.30	11.47	10.70
WSR10	35.12	34.94	34.54	34.50	34.83	33.85
WSR11	13.98	13.96	14.01	13.93	13.76	13.89
WSR12	4.38	4.46	4.43	7.70	7.59	7.67
WSR13	6.29	6.28	6.25	6.33	6.25	6.35
WSR14	0.04	0.04	0.04	0.37	0.37	0.36
WSR15	2.23	2.21	2.20	2.13	2.03	2.14
WSR16	1.08	1.10	1.09	0.90	0.90	0.92
WSR17	11.63	11.69	11.63	10.31	10.77	10.83
WSR18	7.11	7.04	6.97	7.38	7.25	7.25
WSR19	3.60	3.60	3.59	3.58	3.59	3.61
WSR20	13.25	13.06	13.09	10.70	10.77	10.71
WSR21	12.46	12.68	12.70	12.88	12.46	12.58
WSR22a	0.22	0.03	0.03	1.68	0.88	0.72
WSR22b	0.01	0.00	0.00	0.06	0.02	0.01
WSR22c	2.85	0.09	0.08	11.11	3.66	3.41
WSR25	48.88	50.04	50.12	85.90	92.87	96.07
WSR27	0.41	0.01	0.02	0.04	0.00	0.00
WSR28	1.28	0.06	0.04	0.55	0.47	0.39
WSR29	0.03	0.00	0.00	0.37	0.29	0.22
WSR30	0.28	0.25	0.22	2.56	2.65	2.75
WSR31	0.83	0.83	0.81	5.00	4.88	5.05
WSR32	0.02	0.02	0.01	0.13	0.13	0.14
WSR33	0.59	0.59	0.57	2.05	2.00	2.04
WSR34	0.05	0.04	0.04	0.35	0.35	0.34
WSR35	0.46	0.42	0.44	0.43	0.43	0.43
WSR41	22.85	24.41	22.34	33.90	39.09	38.68
WSR42	13.93	14.90	14.19	20.92	21.60	22.34
WSR44	21.17	21.19	21.09	12.94	12.42	13.27
WSR45	13.28	13.19	13.27	12.36	11.89	11.90

[1] For the observation points around Brothers Islands Marine Park (M1-M5), the predicted maximum sedimentation rates would be 9.01-107.4 mg/L for dry season and 8.94-80.27 mg/L for wet season. The details are presented in Appendix 5.4b.

[2] For the observation points around Sha Chau and Lung Kwu Chau Marine Park (M6-M10), the predicted maximum suspended solids elevations in depth averaged would be 13.38-48.99 mg/L for dry season and 19.98-43.58 mg/L for wet season. The details are presented in Appendix 5.4b.

Dissolved Oxygen Depletion

5.5.7.13 The degree of oxygen depletion exerted by a sediment plume is a function of the sediment oxygen demand of the sediment, the concentration in the water column and the rate of oxygen replenishment. In this assessment, the impact of sediment oxygen demand on dissolved oxygen concentrations has been calculated based on the following equation:

DO_Dep = C * COD * K * 0.001

where,

DO_Dep = Dissolved Oxygen depletion (mg/l)

C = SS concentration (kg/m³)

COD = Chemical Oxygen Demand

K = Daily oxygen uptake factor (set at 1.0 for worse case estimate)

5.5.7.14 COD was assumed as 11,600 mg/kg, which is the COD measured in the sediment samples at EPD routine monitoring station NS2 in Year 2014. The above equation does not allow for re-aeration which would tend to reduce any impact of the suspended sediment on the water column DO concentrations. Hence, the analysis is on the conservative side so as not to underestimate the extent of DO depletion. Furthermore, it should be noted that, for sediment in suspension to exert any oxygen demand on the water column will take time and at that time, the sediment will be transported and mixed with oxygenated water. As a result, the oxygen demand and the impact on dissolved oxygen concentrations will diminish as the suspended sediment concentrations decrease.

5.5.7.15 Oxygen depletion is not instantaneous. Previous studies have assumed that the impact of suspended sediment on dissolved oxygen will depend on tidally averaged suspended sediment concentrations. In this study, increase in suspended sediment has been used as the basis for the calculation in order to identify the hypothetical worst case. As such, the daily uptake factor, K, in the equation above is set to 1.0 as that in the HZMB EIAs studies (AEIAR-145/2009, AEIAR-144/2009). This represents instantaneous oxidation of the sediment oxygen demand. It also represents the worst case to ensure oxidation rates are not underestimated. The resulting calculated dissolved oxygen deficit, therefore, is expected to be much larger than that would be experienced in reality.

5.5.7.16 The oxygen depletion exerted by the max SS elevation from month 15, 21 and 31 is calculated in Table 5.32a-c below. The oxygen depletion exerted by the max SS elevation from month 15, 21 and 31 at the affected WSRs under sensitivity scenario with 3RS are summarised in Table 5.32d. It is anticipated that the oxygen depletion at representative WSR will be less than the detection limit of 0.1mg/L. Thus the DO depletion at all sensitive receivers will be insignificant.

Table 5.32a Predicted Maximum Oxygen Depletion (mg/L) for Scenario 03a

WSR	Dry Season				Wet Season
	S	M	B	DA	S	M	B	DA
WSR01	6.42E-03	8.13E-03	8.71E-03	7.87E-03	8.42E-05	1.41E-04	3.32E-04	1.63E-04
WSR02	3.39E-03	4.42E-03	4.79E-03	4.26E-03	3.71E-05	4.48E-05	1.34E-04	4.69E-05
WSR03	1.17E-04	1.43E-04	1.49E-04	1.38E-04	9.00E-06	1.03E-05	2.64E-05	1.43E-05
WSR04	6.70E-05	1.13E-04	2.73E-04	1.14E-04	5.92E-04	4.58E-03	9.61E-03	4.85E-03
WSR05a	4.91E-06	6.98E-06	8.02E-06	6.71E-06	5.15E-05	6.35E-05	9.10E-05	6.36E-05
WSR05b	4.73E-07	1.07E-06	3.32E-06	1.51E-06	2.38E-05	3.29E-05	3.99E-05	3.19E-05
WSR06	5.11E-05	5.81E-05	6.38E-05	5.78E-05	2.90E-04	9.17E-04	6.66E-03	2.00E-03
WSR07	1.77E-06	2.86E-06	3.40E-06	2.57E-06	1.54E-05	3.83E-05	5.52E-05	3.72E-05
WSR08	1.72E-06	3.61E-06	4.28E-06	3.37E-06	1.16E-05	3.27E-05	4.92E-05	2.89E-05
WSR10	1.11E-06	8.26E-06	1.14E-05	7.08E-06	4.52E-06	6.84E-05	1.31E-04	6.45E-05
WSR11	4.46E-06	7.86E-06	1.00E-05	7.19E-06	4.23E-05	8.74E-05	1.04E-04	7.62E-05
WSR12	5.15E-07	1.76E-06	2.65E-06	1.68E-06	1.83E-05	3.87E-05	4.58E-05	3.52E-05
WSR13	1.16E-06	2.47E-06	3.27E-06	2.10E-06	2.04E-05	4.74E-05	5.56E-05	4.34E-05
WSR14	4.29E-09	8.24E-09	1.44E-08	8.79E-09	1.02E-07	1.04E-07	1.82E-06	4.84E-07
WSR15	1.63E-07	4.34E-07	7.11E-07	3.91E-07	2.33E-06	8.60E-06	1.60E-05	7.98E-06
WSR16	3.40E-08	6.78E-08	4.18E-07	1.39E-07	3.60E-07	4.03E-07	6.57E-06	1.47E-06
WSR17	3.66E-06	4.43E-06	4.97E-06	4.06E-06	2.31E-05	2.68E-05	4.11E-05	2.70E-05
WSR18	4.60E-06	6.29E-06	6.51E-06	5.23E-06	2.64E-05	2.59E-05	2.71E-05	2.34E-05
WSR19	1.13E-06	1.98E-06	2.46E-06	1.85E-06	8.82E-06	1.24E-05	1.26E-05	1.16E-05
WSR20	8.16E-06	8.69E-06	8.77E-06	8.41E-06	7.92E-05	7.83E-05	5.65E-05	6.96E-05
WSR21	1.36E-04	2.36E-04	2.91E-04	2.14E-04	1.60E-03	1.88E-03	2.10E-03	1.86E-03
WSR22a	1.90E-04	2.89E-04	3.70E-04	2.86E-04	6.98E-05	2.50E-04	1.10E-03	3.91E-04
WSR22b	1.13E-05	1.97E-05	2.95E-05	2.00E-05	2.47E-06	5.17E-06	1.29E-05	6.33E-06
WSR22c	2.79E-03	4.46E-03	1.31E-02	4.79E-03	3.29E-03	2.06E-02	5.23E-02	2.35E-02
WSR25	2.49E-04	1.43E-03	1.95E-03	1.11E-03	2.91E-03	5.50E-03	7.59E-03	4.28E-03
WSR26	3.34E-04	7.39E-04	1.11E-03	6.67E-04	2.76E-03	4.97E-03	5.58E-03	4.29E-03
WSR27	3.23E-04	3.73E-04	3.64E-04	3.59E-04	1.11E-05	2.15E-05	8.53E-05	3.31E-05
WSR28	7.06E-04	8.55E-04	9.03E-04	8.32E-04	6.13E-05	1.14E-04	1.43E-04	1.05E-04
WSR29	1.20E-05	1.39E-05	1.40E-05	1.33E-05	3.98E-07	1.44E-06	2.48E-06	1.35E-06
WSR30	1.73E-06	2.06E-06	2.10E-06	1.99E-06	4.85E-07	9.52E-07	1.34E-06	7.92E-07
WSR31	1.44E-08	2.43E-08	2.07E-08	2.01E-08	6.35E-08	2.78E-07	5.63E-07	2.97E-07
WSR32	2.00E-10	1.03E-09	2.62E-09	1.26E-09	3.95E-09	1.29E-08	3.08E-08	1.25E-08
WSR33	1.49E-08	2.28E-08	2.91E-08	1.81E-08	1.79E-07	2.44E-07	2.25E-07	1.96E-07
WSR34	1.74E-09	3.38E-09	3.24E-09	2.87E-09	3.32E-08	5.05E-08	6.59E-08	4.00E-08
WSR35	3.52E-08	4.97E-08	5.68E-08	4.24E-08	6.42E-08	7.62E-08	8.31E-08	6.10E-08
WSR41	4.04E-04	1.62E-03	3.05E-03	1.53E-03	1.12E-03	3.79E-03	1.18E-02	4.65E-03
WSR42	1.21E-06	1.51E-06	1.94E-06	1.50E-06	5.52E-06	9.74E-06	1.62E-05	8.89E-06
WSR44	6.15E-04	1.10E-03	1.63E-03	1.10E-03	1.69E-04	2.71E-04	1.14E-03	3.84E-04
WSR45	2.50E-04	5.82E-04	1.02E-03	5.57E-04	1.67E-03	2.63E-03	3.15E-03	2.46E-03

Note:

(1) S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged.

Table 5.32b Predicted Maximum Oxygen Depletion (mg/L) for Scenario 03b

WSR	Dry Season				Wet Season
	S	M	B	DA	S	M	B	DA
WSR01	3.53E-03	4.47E-03	4.78E-03	4.32E-03	4.62E-05	7.77E-05	1.83E-04	8.94E-05
WSR02	1.86E-03	2.43E-03	2.64E-03	2.35E-03	2.04E-05	2.47E-05	7.37E-05	2.58E-05
WSR03	6.48E-05	7.87E-05	8.18E-05	7.61E-05	4.96E-06	5.65E-06	1.46E-05	7.89E-06
WSR04	3.74E-05	6.22E-05	1.51E-04	6.29E-05	3.25E-04	2.52E-03	5.23E-03	2.66E-03
WSR05a	2.74E-06	3.89E-06	4.46E-06	3.74E-06	2.84E-05	3.46E-05	4.87E-05	3.51E-05
WSR05b	2.67E-07	5.94E-07	1.85E-06	8.42E-07	1.30E-05	1.85E-05	2.27E-05	1.80E-05
WSR06	2.86E-05	3.22E-05	3.53E-05	3.21E-05	1.61E-04	5.14E-04	3.59E-03	1.08E-03
WSR07	9.65E-07	1.59E-06	1.94E-06	1.42E-06	8.56E-06	2.15E-05	3.16E-05	2.09E-05
WSR08	9.54E-07	2.00E-06	2.38E-06	1.87E-06	6.43E-06	1.81E-05	2.71E-05	1.58E-05
WSR10	6.18E-07	4.57E-06	6.30E-06	3.91E-06	2.52E-06	3.81E-05	7.29E-05	3.59E-05
WSR11	2.48E-06	4.38E-06	5.59E-06	4.01E-06	2.31E-05	4.84E-05	5.68E-05	4.22E-05
WSR12	2.84E-07	9.80E-07	1.48E-06	9.38E-07	9.92E-06	2.11E-05	2.51E-05	1.92E-05
WSR13	6.35E-07	1.38E-06	1.81E-06	1.17E-06	1.14E-05	2.60E-05	3.05E-05	2.38E-05
WSR14	2.40E-09	4.61E-09	7.98E-09	4.92E-09	5.54E-08	5.66E-08	9.88E-07	2.64E-07
WSR15	8.98E-08	2.41E-07	3.92E-07	2.15E-07	1.29E-06	4.66E-06	8.80E-06	4.34E-06
WSR16	1.87E-08	3.76E-08	2.33E-07	7.74E-08	1.98E-07	2.22E-07	3.55E-06	8.13E-07
WSR17	2.04E-06	2.44E-06	2.73E-06	2.26E-06	1.26E-05	1.48E-05	2.25E-05	1.47E-05
WSR18	2.56E-06	3.46E-06	3.66E-06	2.92E-06	1.45E-05	1.42E-05	1.50E-05	1.28E-05
WSR19	6.35E-07	1.11E-06	1.39E-06	1.04E-06	4.82E-06	6.79E-06	6.88E-06	6.34E-06
WSR20	4.53E-06	4.78E-06	4.83E-06	4.62E-06	4.31E-05	4.26E-05	3.08E-05	3.79E-05
WSR21	7.47E-05	1.29E-04	1.59E-04	1.17E-04	8.85E-04	1.04E-03	1.15E-03	1.03E-03
WSR22a	1.06E-04	1.60E-04	2.05E-04	1.59E-04	3.84E-05	1.39E-04	6.05E-04	2.15E-04
WSR22b	6.20E-06	1.08E-05	1.62E-05	1.09E-05	1.36E-06	2.84E-06	7.07E-06	3.47E-06
WSR22c	1.53E-03	2.45E-03	7.21E-03	2.64E-03	1.81E-03	1.14E-02	2.87E-02	1.29E-02
WSR25	1.37E-04	7.84E-04	1.07E-03	6.09E-04	1.60E-03	3.02E-03	4.21E-03	2.37E-03
WSR26	1.85E-04	4.04E-04	6.05E-04	3.65E-04	1.50E-03	2.73E-03	3.09E-03	2.36E-03
WSR27	1.79E-04	2.06E-04	2.01E-04	1.98E-04	6.15E-06	1.19E-05	4.72E-05	1.83E-05
WSR28	3.91E-04	4.73E-04	5.00E-04	4.61E-04	3.37E-05	6.28E-05	8.00E-05	5.84E-05
WSR29	6.64E-06	7.60E-06	7.68E-06	7.31E-06	2.18E-07	7.89E-07	1.39E-06	7.40E-07
WSR30	9.67E-07	1.15E-06	1.17E-06	1.11E-06	2.16E-07	5.14E-07	7.24E-07	4.28E-07
WSR31	7.93E-09	1.33E-08	1.13E-08	1.10E-08	3.40E-08	1.51E-07	3.07E-07	1.61E-07
WSR32	1.47E-10	6.40E-10	1.85E-09	9.01E-10	2.11E-09	8.30E-09	1.66E-08	6.77E-09
WSR33	1.03E-08	1.15E-08	1.36E-08	9.45E-09	9.76E-08	1.31E-07	1.20E-07	1.06E-07
WSR34	6.18E-10	1.28E-09	2.04E-09	9.09E-10	1.72E-08	2.72E-08	3.58E-08	2.09E-08
WSR35	1.57E-08	3.14E-08	3.43E-08	2.81E-08	3.49E-08	4.15E-08	5.13E-08	3.32E-08
WSR41	2.24E-04	8.90E-04	1.68E-03	8.43E-04	6.22E-04	2.09E-03	6.42E-03	2.58E-03
WSR42	6.67E-07	8.32E-07	1.08E-06	8.24E-07	3.00E-06	5.43E-06	8.89E-06	4.95E-06
WSR44	3.41E-04	6.09E-04	8.99E-04	6.12E-04	9.28E-05	1.47E-04	6.32E-04	2.12E-04
WSR45	1.37E-04	3.19E-04	5.60E-04	3.05E-04	9.16E-04	1.46E-03	1.73E-03	1.36E-03

Note:

(1) S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged.

Table 5.32c Predicted Maximum Oxygen Depletion (mg/L) for Scenario 03c

WSR	Dry Season				Wet Season
	S	M	B	DA	S	M	B	DA
WSR01	3.53E-03	4.47E-03	4.79E-03	4.33E-03	4.64E-05	7.77E-05	1.83E-04	8.95E-05
WSR02	1.86E-03	2.43E-03	2.63E-03	2.34E-03	2.04E-05	2.47E-05	7.35E-05	2.58E-05
WSR03	6.46E-05	7.85E-05	8.14E-05	7.59E-05	4.95E-06	5.64E-06	1.45E-05	7.87E-06
WSR04	3.71E-02	7.31E-02	8.40E-02	6.69E-02	3.23E-02	4.11E-02	4.15E-02	3.27E-02
WSR05a	1.08E-02	1.66E-02	1.65E-02	1.40E-02	8.56E-03	9.75E-03	1.50E-02	9.69E-03
WSR05b	2.58E-03	3.02E-03	6.97E-03	3.36E-03	5.10E-03	7.90E-03	1.04E-02	7.56E-03
WSR06	4.47E-02	9.76E-02	1.24E-01	8.67E-02	3.71E-02	5.44E-02	7.14E-02	5.08E-02
WSR07	8.24E-03	1.20E-02	1.68E-02	1.09E-02	6.05E-03	9.68E-03	1.30E-02	9.64E-03
WSR08	7.68E-03	1.48E-02	1.66E-02	1.35E-02	4.80E-03	1.05E-02	1.42E-02	8.91E-03
WSR10	7.13E-03	3.01E-02	5.09E-02	2.56E-02	2.08E-03	1.67E-02	3.88E-02	1.75E-02
WSR11	9.07E-03	1.46E-02	1.74E-02	1.36E-02	9.38E-03	1.38E-02	1.64E-02	1.20E-02
WSR12	2.23E-03	3.99E-03	5.91E-03	3.70E-03	3.16E-03	7.24E-03	8.58E-03	6.46E-03
WSR13	5.54E-03	7.66E-03	9.25E-03	6.91E-03	3.07E-03	7.21E-03	9.85E-03	6.69E-03
WSR14	2.15E-05	4.11E-05	8.08E-05	4.43E-05	6.57E-05	6.75E-05	3.14E-04	8.22E-05
WSR15	8.99E-04	2.29E-03	2.79E-03	1.88E-03	5.16E-04	1.34E-03	2.42E-03	1.25E-03
WSR16	1.22E-04	2.13E-04	1.27E-03	4.30E-04	2.70E-04	2.40E-04	1.00E-03	2.33E-04
WSR17	1.12E-02	1.36E-02	1.55E-02	1.24E-02	6.12E-03	8.73E-03	1.23E-02	7.80E-03
WSR18	1.10E-02	1.54E-02	1.63E-02	1.38E-02	9.21E-03	1.11E-02	1.26E-02	1.02E-02
WSR19	2.55E-03	4.36E-03	5.39E-03	4.07E-03	3.38E-03	4.81E-03	4.88E-03	4.40E-03
WSR20	1.70E-02	1.85E-02	1.88E-02	1.81E-02	1.44E-02	1.61E-02	1.63E-02	1.54E-02
WSR21	1.60E-02	2.56E-02	2.90E-02	2.37E-02	1.63E-02	1.73E-02	2.54E-02	1.73E-02
WSR22a	2.13E-04	4.23E-04	5.51E-04	3.93E-04	1.19E-03	2.55E-03	2.41E-03	1.92E-03
WSR22b	6.37E-06	1.12E-05	1.75E-05	1.15E-05	1.32E-04	1.36E-04	1.03E-04	1.24E-04
WSR22c	1.54E-03	2.45E-03	7.21E-03	2.64E-03	2.01E-03	1.15E-02	2.91E-02	1.31E-02
WSR25	1.67E-02	2.21E-02	2.46E-02	1.84E-02	2.16E-02	2.84E-02	3.71E-02	2.59E-02
WSR26	1.48E-02	3.13E-02	7.12E-02	3.44E-02	2.61E-02	3.14E-02	3.30E-02	3.03E-02
WSR27	1.78E-04	2.05E-04	2.00E-04	1.98E-04	6.16E-06	1.19E-05	4.69E-05	1.83E-05
WSR28	3.87E-04	4.69E-04	4.94E-04	4.56E-04	3.35E-05	6.21E-05	7.85E-05	5.76E-05
WSR29	6.60E-06	7.56E-06	7.64E-06	7.27E-06	9.02E-06	1.82E-05	1.59E-05	1.45E-05
WSR30	4.15E-06	2.41E-05	3.23E-05	1.90E-05	2.46E-05	7.08E-05	1.15E-04	6.52E-05
WSR31	4.80E-05	8.64E-05	6.49E-05	6.70E-05	4.05E-05	1.66E-04	2.78E-04	1.60E-04
WSR32	2.13E-07	7.14E-07	9.79E-07	5.29E-07	2.20E-06	5.50E-06	1.37E-05	5.65E-06
WSR33	3.07E-05	5.10E-05	5.24E-05	4.42E-05	1.03E-04	1.29E-04	9.60E-05	1.10E-04
WSR34	1.82E-06	2.94E-06	2.70E-06	2.52E-06	1.76E-05	2.17E-05	2.91E-05	1.87E-05
WSR35	2.27E-05	2.48E-05	2.62E-05	2.47E-05	2.86E-05	3.29E-05	3.61E-05	2.64E-05
WSR41	2.98E-02	4.31E-02	4.64E-02	3.63E-02	2.30E-02	4.35E-02	7.15E-02	2.54E-02
WSR42	8.41E-03	9.63E-03	1.07E-02	9.61E-03	2.31E-03	3.97E-03	1.00E-02	3.69E-03
WSR44	7.55E-03	1.05E-02	1.09E-02	8.35E-03	8.93E-03	1.01E-02	1.99E-02	9.57E-03
WSR45	1.94E-02	2.62E-02	3.09E-02	2.43E-02	1.86E-02	1.77E-02	2.57E-02	1.66E-02

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged.

Table 5.32d Predicted Maximum Oxygen Depletion (mg/L) for Scenario 03c and 3RS

WSR	Dry Season				Wet Season
	S	M	B	DA	S	M	B	DA
WSR01	5.21E-03	6.56E-03	7.03E-03	6.36E-03	3.74E-05	2.58E-04	4.65E-04	2.23E-04
WSR02	2.88E-03	3.73E-03	4.05E-03	3.61E-03	1.73E-05	8.77E-05	2.65E-04	1.13E-04
WSR03	1.52E-04	1.88E-04	1.96E-04	1.81E-04	3.90E-06	2.37E-05	4.28E-05	2.06E-05
WSR04	2.31E-02	3.01E-02	3.13E-02	2.66E-02	2.14E-02	2.71E-02	2.66E-02	2.20E-02
WSR05a	1.21E-02	1.70E-02	1.75E-02	1.46E-02	7.91E-03	1.29E-02	1.88E-02	1.16E-02
WSR05b	2.60E-03	2.59E-03	6.25E-03	2.82E-03	6.27E-03	1.00E-02	1.26E-02	9.49E-03
WSR06	2.42E-02	7.06E-02	9.03E-02	6.30E-02	2.81E-02	4.87E-02	6.33E-02	4.41E-02
WSR07	9.24E-03	1.32E-02	1.80E-02	1.19E-02	6.73E-03	1.08E-02	1.53E-02	1.08E-02
WSR08	8.59E-03	1.73E-02	1.91E-02	1.55E-02	4.08E-03	1.07E-02	1.63E-02	9.68E-03
WSR10	1.55E-02	4.51E-02	6.32E-02	3.66E-02	6.80E-03	2.91E-02	7.29E-02	3.40E-02
WSR11	9.98E-03	1.56E-02	1.92E-02	1.45E-02	1.02E-02	1.76E-02	1.96E-02	1.52E-02
WSR12	2.39E-03	4.67E-03	6.32E-03	3.82E-03	3.89E-03	9.26E-03	1.09E-02	8.30E-03
WSR13	6.30E-03	8.22E-03	1.01E-02	7.64E-03	3.25E-03	8.92E-03	1.24E-02	8.62E-03
WSR14	1.43E-05	2.67E-05	4.89E-05	2.65E-05	8.57E-05	9.41E-05	5.04E-04	1.41E-04
WSR15	1.10E-03	2.73E-03	3.26E-03	2.09E-03	7.57E-04	1.59E-03	2.89E-03	1.47E-03
WSR16	9.18E-05	2.98E-04	1.50E-03	5.61E-04	3.47E-04	3.34E-04	1.25E-03	3.90E-04
WSR17	1.22E-02	1.44E-02	1.65E-02	1.37E-02	8.03E-03	1.10E-02	1.55E-02	9.93E-03
WSR18	1.17E-02	1.53E-02	1.63E-02	1.40E-02	1.12E-02	1.26E-02	1.46E-02	1.18E-02
WSR19	3.48E-03	4.94E-03	6.07E-03	4.75E-03	3.44E-03	5.09E-03	5.27E-03	4.68E-03
WSR20	1.86E-02	1.99E-02	2.02E-02	1.96E-02	1.14E-02	1.42E-02	1.47E-02	1.32E-02
WSR21	1.45E-02	2.10E-02	2.41E-02	1.90E-02	8.61E-03	1.37E-02	2.16E-02	1.31E-02
WSR22a	1.22E-04	2.04E-04	3.00E-04	2.04E-04	9.03E-04	1.85E-03	2.26E-03	1.33E-03
WSR22b	6.69E-06	1.16E-05	1.69E-05	1.17E-05	9.89E-05	1.00E-04	7.83E-05	8.81E-05
WSR22c	1.44E-03	2.24E-03	4.62E-03	2.65E-03	1.68E-03	7.44E-03	1.84E-02	8.69E-03
WSR25	2.74E-02	5.61E-02	9.02E-02	4.95E-02	2.21E-02	4.67E-02	1.32E-01	4.57E-02
WSR27	4.65E-04	5.53E-04	5.56E-04	5.33E-04	3.56E-06	1.50E-05	5.61E-05	2.13E-05
WSR28	1.32E-03	1.63E-03	1.74E-03	1.58E-03	2.34E-04	5.49E-04	8.74E-04	4.71E-04
WSR29	4.94E-05	4.93E-05	4.62E-05	4.69E-05	2.11E-04	4.42E-04	5.03E-04	3.88E-04
WSR30	1.02E-04	3.37E-04	4.10E-04	2.59E-04	1.00E-03	2.13E-03	4.28E-03	2.20E-03
WSR31	6.95E-04	1.19E-03	1.13E-03	1.01E-03	2.09E-03	4.43E-03	8.00E-03	3.66E-03
WSR32	4.39E-06	1.45E-05	2.08E-05	1.08E-05	5.37E-05	1.65E-04	1.91E-04	1.19E-04
WSR33	8.03E-04	1.17E-03	1.24E-03	1.03E-03	2.82E-03	3.43E-03	3.14E-03	3.22E-03
WSR34	4.31E-05	7.13E-05	6.46E-05	6.07E-05	3.51E-04	5.31E-04	5.04E-04	4.49E-04
WSR35	6.51E-04	7.13E-04	7.46E-04	7.06E-04	7.23E-04	7.97E-04	7.42E-04	7.47E-04
WSR41	2.65E-02	2.70E-02	3.99E-02	2.43E-02	2.49E-02	2.79E-02	5.43E-02	2.46E-02
WSR42	2.78E-02	3.26E-02	3.70E-02	3.25E-02	1.30E-02	3.12E-02	4.08E-02	2.63E-02
WSR44	2.37E-02	2.98E-02	2.99E-02	2.84E-02	1.61E-02	1.97E-02	2.18E-02	1.94E-02
WSR45	1.31E-02	2.24E-02	2.53E-02	2.05E-02	1.03E-02	1.44E-02	2.05E-02	1.27E-02

Note:

[1] S ¡V Surface Layer, M ¡V Middle Layer; B ¡V Bottom Layer; DA ¡V Depth Averaged.

Contaminant Release from Pore Water

5.5.7.17 Although non-dredged reclamation method will be adopted, contaminant releases from pore water are still anticipated during filling. The pore water analysis results at the sampling locations are shown in Table 5.33a.

Table 5.33a Pore Water Test Results (for those sampling points with exceedance only)

Sampling Location	Metalloid (£gg/L)	TIN (mg/L)	UIA (mg/L)
	As
Criteria / Baseline	10	0.5	0.021
VB1	<10	1.97	0.08
VB2	<10	3.05	0.12
VB3	<10	2.79	0.11
VB4	<10	4.02	0.16
VB5	28	12.82	0.50
VB6	<10	2.50	0.10
VB7	<10	1.34	0.05
VB8	<10	1.16	0.04
VB9	<10	4.09	0.16
VB10	<10	5.21	0.20
VB11	<10	1.14	0.04
VB12	<10	1.11	0.04
VB13	<10	0.93	0.04
VB14	<10	1.34	0.05
VB15	<10	0.76	0.03
VB16	<10	1.06	0.04
VB17	<10	4.39	0.17
VB18	<10	3.57	0.14
VB19	<10	6.37	0.25
VB20	<10	1.11	0.04
VB21	<10	1.01	0.04
VB22	<10	1.01	0.04
VB23	<10	1.42	0.06
VB24	<10	0.86	0.03
VB25	<10	0.97	0.04
VB26	<10	0.93	0.04
VB27	<10	1.19	0.05
VB28	<10	1.36	0.05
Maximum	28	12.82	0.50

5.5.7.18 The concentration of contaminants release from reclamation site to WSRs can be estimated by first order equation^[4]: C(x) = q/(Dx£s£k^0.5). Similar approach has been adopted in previous approved EIA studies^{[5],[6],[7],[8]}. The dilution factor is estimated by assuming the radius of initial release as 10m. The total concentrations of contaminants and nutrients due to construction at the representative ecological WSRs are presented in Table 5.33b. The predicted As and UIA concentrations at these WSRs comply with the proposed criteria. Exceedance of TIN under WQO is observed, the contribution is due to high TIN level in background from Pearl River estuary. There is potential impact by the increase in non-compliance of TIN on the water sensitive receivers taking into account background level and nutrient enrichment effect and potential eutrophication/red tide of the water body due to the increase in TIN non-compliance. According to the literature^[9], the nitrogen and phosphorus (N:P) ratio for red tide growth is 16:1. The growth of most red tide causative species in Hong Kong coastal water has been reported to be optimized at a low N:P (atomic) ratio of between 6 and 15^[10].The N:P ratio from the baseline data at the representative WSRs range from 20:1-26:1. Phosphorus would be the limiting nutrient for the algae growth. The N:P ratio for the prediction of nutrient release from pore water range from 19:1-25:1. Red tide bloom is still limited by the phosphorus level. Thus, drastic increase of red tide occurrence at WSRs is not anticipated.

Table 5.33b Concentration of contaminants and nutrients at representative ecological WSRs from Pore Water Test with background

WSR	Corresponding EPD¡¦s Stations	Baseline Condition						Dilution factor	Metalloid (£gg/L)	TKN (mg/L)	NH3-N (mg/L)	TIN (mg/L)	UIA (mg/L)	Total P (mg/L)	Ortho-P (mg/L)
		TKN (mg/L)	NH3-N (mg/L)	TIN (mg/L)	UIA (mg/L)	Total P (mg/L)	Ortho-P (mg/L)		As
Criteria / Baseline		-	-	0.5	0.021	-	-		25	-	-	0.5	0.021	-	-
WSR01	NM2	0.30	0.107	0.58	0.003	0.04	0.023	285	0.10	0.34	0.152	0.63	0.005	0.05	0.029
WSR04	NM3	0.30	0.107	0.58	0.003	0.04	0.023	375	0.07	0.33	0.141	0.61	0.004	0.05	0.028
WSR06	NM3	0.29	0.108	0.63	0.003	0.04	0.025	279	0.10	0.34	0.154	0.68	0.005	0.05	0.031
WSR20	NM1	0.27	0.093	0.42	0.003	0.04	0.021	1167	0.02	0.28	0.104	0.43	0.003	0.04	0.022
WSR22c	NM2	0.30	0.107	0.58	0.003	0.04	0.023	196	0.14	0.37	0.172	0.65	0.006	0.05	0.032
WSR23	NM2	0.30	0.107	0.58	0.003	0.04	0.023	331	0.08	0.34	0.146	0.62	0.005	0.05	0.028
WSR27	NM2	0.30	0.107	0.58	0.003	0.04	0.023	329	0.09	0.34	0.146	0.62	0.005	0.05	0.028
WSR35	NM8	0.20	0.041	0.47	0.002	0.03	0.018	1870	0.01	0.21	0.048	0.48	0.002	0.03	0.019
WSR41	NM3	0.29	0.108	0.63	0.003	0.04	0.025	310	0.09	0.33	0.149	0.67	0.005	0.05	0.030
WSR42	NM5	0.31	0.122	0.71	0.004	0.05	0.028	1025	0.03	0.32	0.134	0.72	0.004	0.05	0.030
WSR44	NM2	0.30	0.107	0.58	0.003	0.04	0.023	364	0.08	0.34	0.142	0.62	0.004	0.05	0.028
WSR45	NM2	0.30	0.107	0.58	0.003	0.04	0.023	469	0.06	0.33	0.134	0.61	0.004	0.04	0.027

5.5.8 Mitigation Measures

5.5.8.1 The above construction phase water quality assessment has been based on the following design measures:

Design of Construction Method

¡P Based on the latest design, the use of non-dredged reclamation method is adopted.

¡P All reclamation filling works should be conducted within a leading seawall of 200m in advance of reclamation filling.

Good Management Practice in Construction Phase

5.5.8.2 Apart from the design measures, following good site management practices shall be adopted for the filling works:

¡P Water quality monitoring shall be implemented to ensure effective control of water pollution and recommend additional mitigation measures required;

¡P The decent speed of grabs shall be controlled to minimize the seabed impact and to reduce the volume of over-dredging according to the assumed filling rate in water quality assessment in Appendix 5.4a;

¡P A perimeter silt curtain shall be installed during the entire reclamation periods;

¡P Barges or hoppers shall not be filled to a level which will cause overflow of materials or pollution of water during loading or transportation;

¡P Excess materials shall be cleaned from the decks and exposed fittings of barges before the vessels are moved;

¡P Plants should not be operated with leaking pipes and any pipe leakages shall be repaired quickly;

¡P Adequate freeboard shall be maintained on barges to reduce the likelihood of decks being washed by wave action;

¡P All vessels should be sized so that adequate clearance is maintained between vessels and the seabed in all tide conditions, to ensure that undue turbidity is not generated by turbulence from vessel movement or propeller wash; and

¡P The works shall not cause foam, oil, grease, litter or other objectionable matter to be present in the water within and adjacent to the works site.

¡P Mitigation of the pollution generated from general construction activities and sewage from workforce should follow the good practice in Section 5.4.3.

Reuse of C&D materials from the Land-based Works for Filling

5.5.8.3 As discussed in the Waste Management implication in Section 7, all C&D materials arising from the construction would be sorted on-site to recover the inert C&D materials. All sorted inert C&D materials would be reused on-site for the reclamation works. The recovered C&D materials for filling would be ensured no floating or non-inert material by visual inspection, quality assurance, etc.

5.5.9 Residual Impacts

5.5.9.1 With the above design measures and good practices, adverse residual water quality impact is not anticipated. No residual adverse water quality impacts are anticipated.

5.6 Operational Phase Assessment

5.6.1 Identification of Pollution Sources/ Impacts

5.6.1.1 The key pollution sources/ impacts in operational phase includes:

¡P Drainage Discharge and Runoff (including the possible discharge into CA and CPA zonings, and some minor maintenance works)

¡P Sewerage / Sewage Discharge

¡P Change in Hydrodynamic Regime due to Reclamation of Tung Chung East and Road P1 Extension

¡P Emergency Discharge from Proposed Sewage Pumping Stations

¡P Maintenance Dredging and Wastewater & Sewage generated at Proposed Marina

¡P Potential Polluted Runoff from Sports Ground Facility

¡P Maintenance Flushing for Freshwater and Saltwater Reservoirs

5.6.2 Determination of Assessment Year and Concurrent Projects

5.6.2.1 For this Tung Chung project, the first population intake would be in Yr 2024 and the full operation year would be in Yr 2030.

5.6.2.2 The potential concurrent projects for the operational phase are summarized in Table 5.34. Major projects currently under construction, including the TM-CLKL, HKBCF, HKLR and HATS 2A are expected to be completed and in operation before or by end of Year 2016. For the Expansion of HKIA 3RS, it is anticipated to be commissioned by 2023. LLP is a currently planned project and it does not yet have a confirmed completion date. For a conservative assessment, it is assumed to be in operation by Year 2026.

5.6.2.3 The Cumulative Environmental Impact Assessment Study for the Three Potential Nearshore Reclamation Sites in the Western Waters of Hong Kong (CEIA) include the three proposed nearshore reclamation sites in Siu Ho Wan, Lung Kwu Tan and Sunny Bay. The reclamation sites for both Sunny Bay and Lung Kwu Tan are considered as concurrent projects in this study. For Sunny Bay, the reclamation layout in the EIA Study Brief (ESB-272/2014) of Sunny Bay Development was adopted as the best available information. Similarly for the Lung Kwu Tan reclamation, the reclamation layout in CEIA was adopted. For the Siu Ho Wan reclamation, however, the project proponent of LLP has confirmed LLP should still be considered and hence the LLP reclamation layout was adopted. Since the reclamation layout of LLP is larger than the Siu Ho Wan reclamation layout, the incorporation of LLP layout has represented the worst case scenario. Although no implementation programme for Siu Ho Wan, Sunny Bay and Lung Kwu Tan, these reclamations are included in the operational phase assessment.

5.6.2.4 For the projects Providing Sufficient Water Depth at Kwai Tsing Container Basin and its Approach Channel (KTCB) and MDF (South of The Brothers), these projects will not involve land formation, but change in bathymetry. These projects are anticipated to be completed by end 2016.

5.6.2.5 Yr 2030 was adopted as the operational phase assessment year in this study due to full population intake. Water quality modellings for the ¡¥with¡¦ and ¡¥without project¡¦ operational phase scenario were conducted.

Table 5.34 Summary of concurrent projects in operation phase

Proposed/Planned Project in the Vicinity	Tentative Implementation Programme	Status & Consideration in This Study
Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities (HZMB HKBCF, being constructed)	Most of the marine works to be completed by 2016	Land boundary was included in this study. Pollution loading from BCF STW was included
Tuen Mun - Chek Lap Kok Link (TM-CLKL, being constructed)	Most of the marine works to be completed by 2016	Land boundary was included in this study.
Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road (HZMB HKLR, being constructed)	Most of the marine works to be completed by 2016	Land boundary was included in this study.
Harbour Area Treatment Scheme (HATS) Stage 2A	To be commissioned by 2016	Pollution loading was included
Expansion of Hong Kong International Airport into a Three-Runway System (3RS)	To be commissioned by 2023	Land boundary was included in the study. Pollution loading from 3RS was included
Possible Lantau Logistics Park	Not available, assumed to be in operation by Yr 2026 for modelling purpose	Project proponent of LLP has confirmed LLP should still be considered and hence the indicative LLP reclamation layout was adopted. For conservative assessment, pollution load from the proposed STW in Siu Ho Wan reclamation from CEIA was included.
Sunny Bay Development	Not available, assumed to be in operation by Yr 2030 for modelling purpose	The indicative reclamation layout in the EIA Study Brief (ESB-272/2014) of Sunny Bay Development was included. According to CEIA report, the pollution load from the proposed STW for Sunny Bay Development was included.
Lung Kwu Tan reclamation	Not available, assumed to be in operation by Yr 2030 for modelling purpose	The indicative reclamation layout in CEIA was included. According to CEIA, the pollution load from the proposed STW for Lung Kwu Tan reclamation was included.
Providing Sufficient Water Depth at Kwai Tsing Container Basin and its Approach Channel (KTCB)	To be commissioned by 2016	EP (EP-426/2011/A) was issued. The bathymetry was included in this study.
Proposed New Contaminated Mud Marine Disposal Facility at HKIA East/East Sha Chau Area (MDF)	To be commissioned by 2016	EP (EP-427/2011/A and EP-312/2008/A) was issued. The bathymetry was included in this study.

5.6.3 Drainage Discharge and Runoff

Tung Chung West

5.6.3.1 The existing conditions for TCW development is partially rural area. With the development of the Project, there would be an increase in the total paved area. Such change of pavement will reduce the infiltration rate in the catchment, consequently resulting in a higher flood risk as extra stormwater runoff may be generated during rain events. The flood risks will be assessed and addressed separately in the Drainage Impact Assessment Report under this study. It is recommended that the capacities of road drainage system shall cater for the runoff for 50 year-return-period rainstorm events.

5.6.3.2 In terms of water quality impact, there would be additional pollution loading due to the increase of runoff, which is known as non-point source pollutions during operational phase. Substances such as vehicle dust, tyre scraps and oils deposited and accumulated on the road surfaces will be washed into nearby drainage system or watercourses during rainfall events. Some minor maintenance works such as landscaping work at the polder or inside River Park will be conducted during the operations of stormwater attenuation and treatment ponds, SUDS, River Park and associated drainage facilities. The minor maintenance works would be well controlled and managed by the relevant government departments so that the treated surface runoff to Tung Chung Stream in the maintenance period would comply with the WPCO.

5.6.3.3 The TCW development is located within the catchment of Tung Chung Stream, which covers North and South Lantau Country Park with total area of over 1100 ha. The change of effective catchment area due to TCW development is around 35.6 ha, accounting for less than 3% of the whole catchment which could be considered negligible.

5.6.3.4 Given the high ecological value in river mouth of Tung Chung Stream, the effective catchment area will remain as current conditions. Extra runoff due to the additional paved surface from the project will be attenuated and treated by a set of regional stormwater attenuation and treatment ponds. All runoff from within the catchment will run via the new drainage system, treated and then temporarily stored in the stormwater attenuation and treatment ponds (see RODP at Figure 2.2). A discharge spillway will be installed at each pond. When the water level reaches the top of the discharge spillway runoff will be diverted back into Tung Chung Stream. To provide flood protection, temporarily stored runoff within each pond will discharge slowly back to the Stream. Thus the stormwater attenuation and treatment ponds mitigate the extra runoff by capturing and treating the first flush rainfall and attenuating large flows. In the dry season, water quality deterioration due to stagnant situation in the stormwater attenuation and treatment ponds would be avoided with the implementation of suitable design measures, such as installation of subsurface drainage to eliminate areas of standing water, implementation of maintenance activities to remove any organic debris and to clear areas of stagnation etc., to be determined during detailed design stage to ensure compliance with the WPCO discharge standards. Therefore, change in hydrology and non-point source loading regime at Tung Chung Stream catchment is not anticipated

5.6.3.5 The cumulative water quality impact due to non-point source loading without enhancement measures from TCW development was included in the hydrodynamic and water quality modelling as described in Section 5.3.4 and Section 5.3.5. Enhancement measures recommended include provision of stormwater attenuation and treatment ponds and dry weather flow interceptor at the existing villages as discussed in Section 5.6.8.

Tung Chung East

5.6.3.6 TCE development will be a newly reclaimed land. Additional non-point source loading will be due to surface runoff from the reclamation land. In order to minimize the impact, silt traps and best management practices such as regular road cleaning shall be implemented. The cumulative water quality impact due to non-point source loading from TCE development are included in the hydrodynamic and water quality modelling as described in Section 5.3.4 and Section 5.3.5.

5.6.4 Sewerage / Sewage Discharge

5.6.4.1 During operational phase, sewage discharge will be the major water pollution source. These include domestic sewage from development for both TCE and TCW.

5.6.4.2 For individual commercial tenants, discharge license under WPCO will be required individually and the discharge standards according to TM-DSS to government foul sewers will be applied.

5.6.4.3 According to current design, all sewage generated from the development will be diverted to Siu Ho Wan STW. The sewage treatment capacity reserved at the SHWSTW is adequate to cater for the increased sewage arisen from this Project. Hence neither upgrading nor additional mitigation measure for SHWSTW is required due to this project. However, fitting out works of SHWSTW will be carried out by DSD in a timely manner to cater for the projected flows from existing dischargers and committed projects within its catchment. Details of sewage and sewerage implication are presented in Section 6.

5.6.5 Emergency Discharge from Sewage Pumping Stations

5.6.5.1 Five new sewage pumping stations (SPSs) and one upgraded SPS are proposed for this project. Their locations are shown in Figure 6.1-6.10. Two sewage pumping stations, TCE East SPS and TCE West SPS, are located in southeast corner and southwest development near MTR TCL for TCE. The Chung Man Road SPS (CMRSPS) will be upgraded. Another three new SPSs, TCV East SPS, TCV North SPS and TCV West SPS are proposed for Tung Chung West and Valley Development. The estimated sewage flows for the proposed and upgraded sewage pumping stations are presented in Table 5.35a -5.35c. The sewage pumping stations will collect the sewage from the development and convey the sewage to the Siu Ho Wan Sewage Treatment Works.

5.6.5.2 Given the sensitivity of Tung Chung Stream in term of water quality and ecology and low flushing rate in the semi-enclosed water body at the north of TCE, extensive effort has been expedited to avoid the need for emergency discharges. In order to achieve this, the design of the SPSs have been cautiously reviewed to include additional provisions including a) 100% standby pumping capacity plus spare pump with 50% pumping capacity, b) twin rising mains; c) dual-feed power supply; d) emergency storage facilities up to 6-hour ADWF capacity; e) emergency communication mechanism amongst relevant government departments. (see Section 5.6.10.3 for more information). As discussed with DSD, with these additional provisions, emergency discharge from TCV East SPS, TCV North SPS, TCV West SPS and proposed upgrading of Chung Man Road SPS in TCW, TCE West SPS and East SPS in TCE is not anticipated.

Table 5.35a Estimated Sewage Flows for Proposed Sewage Pumping Stations to serve TCE Development

SPS	Area Served	ADWF (m^3/day)	Peaking Factor	Peak Flow (l/s)
TCE West SPS (Ultimate Stage)	New development areas in the western portion of Tung Chung East and Area 56	12,891	3.00	448
TCE East SPS (Ultimate Stage)	All new development areas in Tung Chung East and Area 56	45,732	2.79	1,479

Table 5.35b Estimated Sewage Flows for Upgraded Sewage Pumping Stations to serve TCW and Valley Development

SPS	Area Served	ADWF (m^3/day)	Peaking Factor	Peak Flow (l/s)
Upgraded CMRSPS	New development areas TCW-1, TCW-2, TCW-3, TCV-1, COM-1, COM-2, COM-3 and existing villages Ma Wan Chung and Wong Nai Uk	3,119	3.50	126

Table 5.35c Estimated Sewage Flows for Proposed Sewage Pumping Stations to serve TCW and Valley Development

SPS	Area Served	ADWF (m3/day)	Peaking Factor	Peak Flow (l/s)
TCV West SPS	New development areas TCV-3, TCV-4 and existing villages Mok Ka, Lam Che and Nim Yuen	551	4.00	26
TCV North SPS	New development area TCV-8 and existing village Ngau Au	278	6.00	19
TCV East SPS	All new development areas in TCW and existing villages Mok Ka, Lam Che, Nim Yuen, Shek Mun Kap, Ngau Au, Shek Lau Po, Ma Wan Chung and Wong Nai Uk	8,864	3.00	308

5.6.6 Water Quality for the Proposed Marina

Maintenance Dredging

5.6.6.1 Maintenance dredging will be carried out to allow vessels to berth within the marina at low tide and to enhance navigational safety. Maintenance dredging for the proposed marina usually to be conducted for every 1-3 years. Derrick lighter with small grab capacity of approximately 2 m³ will need to be employed due to the shallow water depth and limited space inside the marina as well as the limitation on anchorage length. Based on the area of marina of 42,000m² and sedimentation rate of 0.4mm per year predicted from the model (Drawing: Annual-Sed in Appendix 5.7), the predicted volume of dredged material would be relatively small as compared with the construction phase impact. The maintenance dredging would be conducted in scheduled manner with much slower rate within a semi-enclosed bay. Together with the deployment of silt curtain, the dispersion of SS would be well controlled and constrained locally. The SS impact for maintenance dredging to the WSRs is not anticipated to be significant.

Wastewater & Sewage

5.6.6.2 Subject to the detailed design by the future operator, there may be boatyard, maintenance area and polder in the development at the proposed marina. According to WPCO, discharge of the following matters into coastal waters from any maintenance activities etc. are prohibited: PCB, PAH, fumigant, pesticides, toxicant, chlorinated hydrocarbons, flammable or toxic solvents, petroleum oil or tar, wastes liable to form scum, deposits or discolouration, sludge or solid refuse of any kind under TM-DSS.

5.6.6.3 A sewerage system will be provided for the boatyard and maintenance area in the proposed marina at the north of TCE. All the sewage and wastewater generated from the operation of the maintenance activities will be conveyed to Siu Ho Wan STW for treatment. The effluent will be treated to meet the TM-DSS before discharging to the public sewerage. Hence, the operation of the maintenance activities is not anticipated to cause unacceptable water quality impact.

5.6.6.4 Besides, the current design has not allowed any storm water outfalls to be discharged into the proposed marina. Similar to the other marina, maintenance and clean-up would be conducted regularly by the operator. Accumulation of pollutant e.g. fuel slick or other floating refuse in the marina is not anticipated.

5.6.6.5 The proposed marina is a designated project under O.2, Part I, Schedule 2 Designated Project requiring EPs. Hence, a separate EIA study for proposed marina will be conducted by the future project proponent. The EIA shall formulate a management plan to avoid adverse water quality impact.

5.6.7 Potential Polluted Runoff from Sports Ground Facility

5.6.7.1 According to the TM-DSS, effluent discharge into coastal water should meet the statutory standards. Prohibited substances including PCB, PAH, fumigant, pesticide are not allowed to discharge into coastal water. The design of the sports ground facility shall implement all the necessary measures to ensure that the effluent discharged into coastal water would meet the legislative requirement. For example, PCB, PAH, fumigant, pesticides, toxicant, chlorinated hydrocarbons, flammable or toxic solvents, petroleum oil or tar, wastes liable to form scum, deposits or discolouration, sludge or solid refuse are prohibited to be discharged into coastal water. The sports ground facility is a designated project under O.7, Part I, Schedule 2 Designated Project requiring EPs. Hence, a separated EIA study for sports ground facility will be conducted by its project proponent. The EIA shall also formulate a management plan to avoid adverse water quality impact.

5.6.8 Maintenance Flushing for Freshwater and Saltwater Reservoirs

5.6.8.1 As discussed in Section 2, the proposed freshwater and saltwater reservoirs would be located near to the two existing freshwater reservoirs up in the terrain west of Chek Lap Kok New Village. Under normal situation, there is no discharge from the service reservoir to the nearby water body. As part of the necessary maintenance tasks, these reservoirs would need to be flushed for cleaning but the frequency is not high.  During flushing, the water would be discharged via the washout pipes at a controlled manner.  Similar procedures are applicable for all services reservoirs.  The current design has allowed the flushing water to be discharged into the channelized section of Wong Lung Hang which has limited ecological value.  This discharged water would follow the channelized section and reach the water body to the east of Sha Tsiu Tau, which is brackish water with a varying salinity.  Hence, given the amount of flushing water to be discharged is not significant and the frequency of discharge is low, it is considered that those flushing water would not cause significant changes to the water quality in the vicinity of Sha Tsiu Tau. Compliance with WPCO for discharge of wastewater will be ensured during the operation of reservoir flushing.

5.6.9 Hydrodynamic and Water Quality Impact Assessment

5.6.9.1 According to the current design, reclamation will be required in TCE. It may affect the hydrodynamic regime in the area and cause deterioration in the water quality. The design capacity of Siu Ho Wan STW was checked and is able to cater for the sewage generated by Tung Chung population.

Assessment Scenario

5.6.9.2 Hydrodynamic and water quality simulations for the following scenarios have been conducted.

¡P Do-nothing - Hydrodynamic and water quality (Scenario 01) simulation without the project in place with ultimate coastline configuration)

¡P Operation - Hydrodynamic and water quality (Scenario 02) simulation with the project in place with ultimate coastline configuration)

Pollution Load Inventory

5.6.9.3 The sewage generated from the project will be diverted to Siu Ho Wan STW. The design plant capacity of Siu Ho Wan STW is 180,000m³/day. It is anticipated that the Siu Ho Wan STW is able to cater for the increased sewage generated from the project. There is no additional sewage treatment works required under this project. However, fitting out works of SHWSTW are to be completed by DSD in a timely manner to cater to the projected flows within its catchment.

5.6.9.4 For the sake of modelling of operation phase, the effluent discharge from major STWs, including Siu Ho Wan STW, Pillar Point STW, Yuen Long STW, San Wai STW, Shatin STW, Tai Po STW, Stonecutters Island STW, and Sham Tseng STW in the North Western WCZ and Western Buffer WCZ. Victoria Harbour WCZ and Deep Bay WCZ were updated according to the latest information on design plant capacity and discharge license requirement for the pollution loads. The pollution loading from major STWs were updated according to the design plant capacity and discharge licenses. The loading from storm drain out of the project was adopted from the Ultimate Year (Yr.2030) scenario under HATS Stage 2A EIA. The increase in storm drain loading due to the project is calculated based on population intake of Tung Chung project. The methodology of calculation of storm drain loading is made reference to HATS Stage 2A EIA Study.

5.6.9.5 The major pollution load due to the project will be the road runoff from both TCE and TCW development. The non-point source pollution loading due to Tung Chung project is presented in Appendix 5.5. The total loading of non-point source pollution due to the development in terms of BOD₅, TN and TP are 113 kg/day, 9 kg/day and 1 kg/day respectively. The proposed SUDS was not taken into account. These pollution loadings were incorporated into the water quality modelling in operational phase as a conservative scenario.

Hydrodynamic Impact

5.6.9.6 The tidal flows simulations for Scenario H1 and H2 are presented in Appendix 5.6.

Channels

5.6.9.7 The accumulated flow, momentary flow and total salinity flux at four major channels around the study site, namely, 1) Airport Channel, 2) BCF South and 3) Airport North and 4) Ma Wan for both Scenario H1 and Scenario H2 are presented in Appendix 5.6. As shown in Appendix 5.6, there are insignificant changes in accumulated flow, momentary flow and total salinity flux for Airport North and Ma Wan, as these two channels are far away from the development. However, there are observable changes for Airport Channel and BCF South due to the TCE reclamation. The accumulated flow, momentary flow and total salinity flux are shown in Table 5.36a-c respectively.

Table 5.36a Comparison Results of Accumulated Flow at Concerned Channels

Channels	Seasons	Accumulated Flow (m^3)		Difference (m^3)
		Scenario H1	Scenario H2
Airport Channel	Dry	-6.78E+07	-7.61E+07	-8.30E+06
	Wet	5.04E+07	3.31E+07	-1.73E+07
BCF South	Dry	-5.56E+07	-6.63E+07	-1.07E+07
	Wet	9.55E+07	6.64E+07	-2.91E+07

Table 5.36b Comparison Results of Momentary Flow at Concerned Channels

Channels	Seasons	Momentary Flow (m^3/s)
		Scenario H1	Scenario H2
Airport Channel	Dry	-5.17E+02 ~ 4.82E+02	-5.00E+02 ~ 4.45E+02
	Wet	-4.39E+02 ~ 6.20E+02	-4.32E+02 ~ 5.59E+02
BCF South	Dry	-1.22E+03 ~ 1.33E+03	-1.12E+03 ~ 1.16E+03
	Wet	-1.14E+03 ~ 1.54E+03	-1.04E+03 ~ 1.34E+03

Table 5.36c Comparison results of total salinity flux at concerned channels

Channels	Seasons	Salinity Flux (kg/s)		Difference (kg/s)
		Scenario H1	Scenario H2
Airport Channel	Dry	-2.01E+09	-2.25E+09	-2.40E+08
	Wet	8.17E+08	5.15E+08	-3.02E+08
BCF South	Dry	-1.64E+09	-1.96E+09	-3.20E+08
	Wet	1.76E+09	1.27E+09	-4.90E+08

5.6.9.8 The accumulated flow in Airport Channel decreases in wet season and increases in dry season. Similarly, the accumulated flow in BCF South decreases in wet season and increases in dry season. The total salinity flux in Airport Channel decreases in wet season and increases in dry season. Similarly, the total salinity flux in BCF South decreases in wet season and increases in dry season (Appendix 5.6). For the predicted momentary flow across the Airport Channel and BCF South, there is a very small decrease.

5.6.9.9 The change in accumulated flow and total salinity flux does not however represent significant change in flow discharge in absolute terms. The changes in momentary flow and accumulated flow suggest that there may be change in flushing of the water body. However, the water quality result does not show significant change in this Airport Channel and BCF South despite the flow change (see Appendix 5.7 and Table A.1-A.8). Therefore, it is not anticipated that the flow change in Airport Channel and BCF South will affect the water quality in this area.

5.6.9.10 Table 5.37 shows the maximum velocity at the key WSRs in the vicinity. As shown in Table 5.37, there is no significant change in maximum velocity at WSR 04, WSR25, WSR30 and WSR31, which is far away from the development during dry and wet seasons. At Tai Ho Wan Inlet (Inside) (WSR 22b), there is no change in the flow as it is controlled mainly by tidal flow. There is slight decrease in flow magnitude of WSRs near the development such as Tai Ho Wan Inlet (Outside) (WSR 22c), San Tau Beach SSSI (WSR 27) and Hau Hok Wan (WSR 29) in wet season. However, the change of water quality due to project is small as shown in Table A.1-A.8 of Appendix 5.7. For example, the percentage change of salinity, depth averaged DO and SS at San Tau Beach SSSI (WSR 27) in wet season are -0.1%, 3.5%, 1.4% respectively and at Hau Hok Wan (WSR 29) are 0.6%, 2.9%, 1.1% respectively.

5.6.9.11 The flow directions near the Project Site during dry and wet seasons at both flood and ebb tides are shown in Drawings VE-Dry, VF-Dry, VE-Wet, VF-Wet of Appendix 5.6, which indicates that change of flow directions are insignificant with the reclamation.

Table 5.37 Comparison Results of Maximum Flow Velocity at Concerned WSRs

Observation Points	Seasons	Maximum Velocity (m/s)		Difference (m/s)
		Scenario H1	Scenario H2
Proposed Marine Park at Brothers (WSR 04)	Dry	0.6287	0.6331	0.0044
	Wet	0.6819	0.6877	0.0058
Tai Ho Wan Inlet (Inside) (WSR 22b)	Dry	0.053	0.052	-0.001
	Wet	0.053	0.052	-0.001
Tai Ho Wan Inlet (Outside) (WSR 22c)	Dry	0.2404	0.2109	-0.0295
	Wet	0.2824	0.2092	-0.0732
Cooling water Intake at HKIA (WSR25)	Dry	0.0834	0.0832	-0.0002
	Wet	0.0775	0.0772	-0.0003
San Tau Beach SSSI (WSR 27)	Dry	0.100	0.098	-0.002
	Wet	0.142	0.121	-0.021
Airport Channel (Hau Hok Wan) (WSR 29)	Dry	0.1321	0.1282	-0.0039
	Wet	0.2013	0.1752	-0.0261
Sha Lo Wan (WSR30)	Dry	0.1314	0.1293	-0.0021
	Wet	0.2072	0.2085	0.0013
Sham Wat Wan (WSR 31)	Dry	0.0611	0.0617	0.0006
	Wet	0.1105	0.1101	-0.0004

Water Quality Impact

5.6.9.12 The overall water quality is affected by the pollution loads. The major pollution sources would be the runoff from Pearl River and loading from Siu Ho Wan STW and Pillar Point STW, San Wai STW, etc..

5.6.9.13 Additional discharge from induced pavement runoff is anticipated. These loadings are considered to be minor on comparing to the loading from Pearl River and STW discharges. The simulations of water quality impact under Scenario 01 and 02 have been conducted and the water quality modeling results are presented in Appendix 5.7.

5.6.9.14 Table A.1-A.8 in Appendix 5.7 summarizes the comparison results of the following parameters, salinity, DO, BOD₅, SS, TIN, unionized ammonia (UIA), and E.coli at WSRs under Scenario 01 and Scenario 02.

Salinity

5.6.9.15 Table A.1-A.8 in Appendix 5.7 compare the annual depth- averaged salinity between Scenario 01 and Scenario 02 at WSRs. The contours of salinity are presented in Appendix 5.7. Results indicate that the difference in salinity are within 10% of the base case at the representative WSRs, which comply with WQO criteria.

Dissolved Oxygen (DO)

5.6.9.16 Table A.1-A.8 in Appendix 5.7 compares the annual depth-averaged DO levels and the near-bottom DO levels between Scenario 01 and Scenario 02 at WSRs. The contours of DO are presented in Appendix 5.7. Results indicate that the depth-averaged DO levels and the near-bottom DO levels at representative WSRs would be within the WQO (i.e. Depth averaged DO > 4mg/L and bottom DO > 2mg/L).

Biological Oxygen Demand (BOD₅)

5.6.9.17 Table A.1-A.8 in Appendix 5.7 compare the annual depth averaged BOD₅ between Scenario 01 and Scenario 02 at WSRs. The contours of BOD₅ are presented in Appendix 5.7. The only applicable BOD₅ criteria is for seawater intakes. For seawater intakes WSR 23 (LLP), WSR 43 (Tung Chung) and WSR44 (BCF), the results indicate that the BOD₅ levels are in compliance with WSD criteria. For the other WSRs, there is no WQO for BOD₅. Inside the proposed marina, the maximum BOD₅ level increases slightly from 2.0mg/L to 2.5mg/L in wet season. However, the depth-averaged DO level inside the proposed marina is about 7mg/L which is still above and comply with the WQO of 4mg/L. Inside the Tung Chung Bay, there is a slight increase in BOD, which is due to the increase in runoff and paved area in Tung Chung West. For the sake of conservation, the water quality assessment has not included the effectiveness of the SUDS proposed as enhancement measure in Section 5.6.11. In the real situation, the SUDS will help improve the water quality before discharging to Tung Chung Stream due to increased surface runoff.

Suspended Solids (SS)

5.6.9.18 Table A.1-A.8 in Appendix 5.7 compare the annual depth-averaged SS between Scenario 01 and Scenario 02 at WSRs. The contours of SS are presented in Appendix 5.7. Results indicate that the difference in SS is within the WQO criteria of 30% increase at all WSRs, except seawater intake. At the seawater intakes (e.g. WSR 23 at LLP, WSR 43 at Tung Chung and WSR44 at BCF), the predicted SS levels are within the WSD criteria (i.e. <10 mg/L) for the project scenario.

Total Inorganic Nitrogen (TIN)

5.6.9.19 Table A.1-A.8 in Appendix 5.7 compares the annual TIN levels between Scenario 01 and Scenario 02 at WSRs. Most of the WSRs comply with the WQO in TIN criteria of 0.5mg/L. The WSRs in Tung Chung Bay (WSR 01-03), the TIN level increases slightly. For example the TIN level increases from 0.25mg/ L to 0.28mg/L at WSR 01 (Yat Tung East Channel). However the TIN level is still within the criteria of 0.5mg/L. However, the annual TIN level is still within 0.5mg/L criteria. At WSR 10 (Sha Chau and Lung Kwu Chau Marine Park). exceedance of the annual mean depth-averaged TIN criteria is observed under the project scenario, which is in 0.53 mg/L. For the without project scenario, exceedance of the annual mean depth-averaged TIN criteria is also observed at WSR 10 by the same magnitude. This suggests that the Tung Chung reclamation will have insignificant effect on the TIN. The high TIN level is due to the background from Pearl River estuary.

UIA (Unionised Ammonia, NH₃)

5.6.9.20 Table A.1-A.8 in Appendix 5.7 compare the annual UIA levels between Scenario 01 and Scenario 02 at WSRs. The contours of UIA are presented in Appendix 5.7. The results show that the depth-averaged UIA at WSRs would be within the WQO.

Sedimentation

5.6.9.21 Appendix 5.7 shows the predicted annual sedimentation rate (m/year) for Scenario 01 and Scenario 02 by assuming sediment density of 750 kg/m³, a sedimentation rate in units of m/year is derived. The findings show that majority of locations would experience no appreciable change in sedimentation rates after implementation of the project. The only notable differences occur at Tung Chung estuary and coast of TCE reclamation, whereby sedimentation is predicted to increase by less than <0.4 mm per year after implementation of the project. This difference is considered to be insignificant and is unlikely to lead to any adverse impacts on WSRs.

E. coli

5.6.9.22 Table A.1-A.8 in Appendix 5.7 compares the annual E. coli levels between Scenario 01 and Scenario 02 at WSRs. The contours of E. coli are presented in Appendix 5.7. The E. coli levels are within the WQO criteria which is 20,000 count/100ml at seawater intakes WSR 23 (LLP), WSR 43 (Tung Chung) and WSR 44 (BCF), 610 count/100ml at fish culture zone WSR 20 (Ma Wan), 610 count/100ml at secondary contact recreation subzone such as WSR 16 (Gold Coast Marina), 180 count/100ml for bathing season at beaches such as WSR 15 (Gazetted Beaches at Tuen Mun), WSR 18 (Gazetted beaches along Castle Peak Road) and WSR 19 (Gazetted beaches at Ma Wan). No adverse impacts are anticipated due to the implementation of the project.

5.6.10 Mitigation Measures

Emergency Discharge of Proposed TCV West SPS, TCV East SPS, TCV North SPS, Upgraded CMRSPS, Proposed TCE West SPS and TCE East SPS

5.6.10.1 For the protection of ecological sensitive receivers of Tung Chug River and Tai Ho Bay, the following mitigation measures will be implemented to TCV East, North and West SPS, upgraded CMRSPS, Proposed TCE West SPS and TCE East SPS:

¡P 100% standby pumping capacity with spare pump up to 50% pumping capacity

¡P Twin rising mains

¡P Dual-feed power supply

¡P Emergency storage facilities up to 6-hours ADWF capacity;

¡P Emergency communication mechanism amongst relevant government departments

With the implemented mitigation measures, emergency sewage overflow to the Tung Chung Stream from SPSs in TCV or to the sea at the north side of TCE from SPSs in TCE is not anticipated.

Emergency Discharge due to Pipe Bursting

5.6.10.2 In order to reduce the impact of emergency discharge due to pipe bursting, it is proposed to adopt high density polyethylene (HDPE) pipe for proposed gravity sewers and rising mains. As gravity sewers will not be pressurized, they carry no risk of bursting. Further protection on proposed rising mains with concrete surround will be provided to mitigate the risk of bursting. With the above measures, bursting discharge is not expected and thus no adverse impact on water quality due to bursting discharge is anticipated.

Maintenance Dredging for the Proposed Marina

5.6.10.3 The volume of dredged material would be relatively small as compared with the construction phase impact. As the SS release would be within a semi-enclosed bay, the dispersion of SS would be constrained locally. The SS impact to the closest waiter sensitive receiver WSR 43 future seawater intake for Tung Chung, which is located 1.2km far away from the mouth of marina, is not anticipated. Silt curtain should be deployed to reduce the sediment dispersion from the dredging inside the marina.

5.6.11 Enhancement Measures

Conventional Measures by Silt Trap and Road Cleaning in TCE and TCW

5.6.11.1 Under normal condition, surface runoff will not be generated in low rainfall intensity. However, the worst scenario to water quality will take place during the first flush under heavy rainstorm events. Under conventional measures, surface runoff can be controlled by proper drainage systems with silt traps and best management practice. Runoff would be intercepted by properly designed and managed silt traps at appropriate spacing so that common roadside debris, refuse and fallen leaves etc. can be captured before discharge. The road/ open area cleaning at the drainage outlets should also be properly managed prior to the occurrence of a storm. Manual methods and mechanical means such as vacuum sweeper/truck equipped with side broom to increase removal efficiency of pollutants are the common practices. The collected debris would be tankered away for off-site disposal at landfill sites. After the removal of the debris, the pollution levels from stormwater would be much reduced. With the implementation of silt traps and road cleaning, the impact to Tung Chung Stream due to surface runoff is insignificant.

Introducing Sustainable Urban Drainage System (SUDS) in TCW for Tung Chung Stream

5.6.11.2 Though the impact to Tung Chung Stream due to surface runoff would be insignificant with the implementation of silt traps and road cleaning, Sustainable Urban Drainage System is introduced to further enhance the protection of Tung Chung Stream. The existing catchment at TCW has an area of about 11km².  It includes the upstream vegetated catchment of the North and South Lantau Country Park with scattered villages and the downstream urban catchment of the Tung Chung Town. Tung Chung Stream is the main river network serving this catchment area and it discharges downstream to Tung Chung Bay. According to the DSD¡¦s List of Flooding Blackspots (http://www.dsd.gov.hk/EN/Flood_Prevention/Our_Flooding_Situation/Flooding_Blackspots/index.html), there is no DSD flooding blackspot within the vicinity of the Project.

5.6.11.3 Unlike the conventional drainage system in which surface runoff would pass through gullies to filter off dirt and debris and then discharged into the receiving water bodies, the proposed SUDS within TCW includes a number of new and innovative features to address the high ecological concern of Tung Chung Stream and the downstream estuary. (See Section 9 for more details). According to the latest design, the new system would include the provision of a series of regional stormwater attenuation and treatment ponds. During rainfall events, flows will be directed into the stormwater attenuation and treatment ponds which are capable to manage peak flows and remove pollutants. Runoff from the proposed development areas will be directed toward onsite stormwater attenuation and treatment ponds and the treated runoff will be diverted back into Tung Chung Stream. The ponds will have a vegetated wetland zone and permanent pool, which will create valuable open space amenity and increase biodiversity. The capacity of those stormwater attenuation and treatment ponds would vary from 3,000 ¡V 5,000m³, depending on the catchment served.

5.6.11.4 As shown in Appendix 5.8, the runoff from roadways, parcels, and existing villages will be diverted via dedicated ¡§dirty¡¨ pipe network and discharged to a primary sedimentation zone or ¡§forebay.¡¨ Runoff will be slowed to allow sediment to settle out. Retaining sediment at the forebay rather than in the larger detention zone will allow for easier removal, thus minimize maintenance costs.

5.6.11.5 At the opposite end of the forebay, runoff will enter a wide and shallow biofiltration wetland zone. Treatment action will occur as stormwater travels slowly through dense, climate-appropriate landscaping, removing floating debris and encouraging the uptake of nutrients by the plants. Following the biofiltration wetland zone, treated flows will be discharged into the permanent pool or attenuation zone.

5.6.11.6 During large rainfall events, high flows will bypass the forebay and biofiltration wetland zone and be directed into the attenuation zone. This zone will contain high- and low-flow weirs to mitigate peak flows due to the planned development, keeping the rate of discharge to the Tung Chung Stream at or below the existing condition. In occasional high storm events in which the water level in Tung Chung Stream is higher than that of the attention ponds, a high flow pump will be activated to pump the water from the attenuation zone to the Tung Chung Stream.

5.6.11.7 The sediment and pollutants in the runoff are designed to be trapped within 3-stages of treatment pond. It should be noted that some overseas examples similar to the proposed SUDS for TCW have been successfully implemented for some years. (e.g. treatment pond at Bay Meadows, California USA, attenuation pond at Land Port of Entry, Maryland USA, sedimentation pond at Yishun Pond, Singapore etc). According to the USA studies, the substantial pollutant removal performance by SUDS and treatment ponds are summarized in Table 5.38. As shown in the table, sediment, nutrients, metals and bacteria can be removed in the SUDS and treatment ponds.

Table 5.38 Substantial Pollutant Removal Performance by SUDS and Treatment Ponds

	¡§Polluted¡¨ Runoff Containment	SUDS Removal	Treatment Ponds Removal	¡§Treated¡¨ Runoff Containment
Sediment	100%	80%	80%	4%
Nutrients	100%	60%	50%	20%
Metals	100%	70%	60%	12%
Bacteria	100%	40%	70%	18%

5.6.11.8 Besides, green channel design, such as grasscrete and gabion embankments etc., would be considered in the design of drainage system to improve aesthetic and biodiversity, which in turn enhancing the greening within the Tung Chung Valley. With the implementation of SUDS, the pollution load to Tung Chung Stream due to increased surface runoff would be further reduced.

5.6.11.9 Source-control SUDS techniques are aimed at preventing pollutants from entering the storm drainage network by diverting them to a controlled location for easy and low-cost removal. Some suitable examples under consideration at proposed developments and within adjacent villages include:

1) Street Sweeping ¡V maintain cleanliness of street surfaces by routinely sweeping with a vacuum truck to remove organic debris, litter, and sediment.

2) Vehicle Washing Stations ¡V construct protected areas within each village dedicated to the washing of vehicles and prohibit washing in other areas. The paved washing station should be self-contained with runoff being diverted to an adjacent filter system or sanitary sewer drain.

3) Educational Signage ¡V install signage near storm drain inlets and along the banks of local streams to prevent illegal dumping of concentrated pollutants and debris.

4) Oil/Water Separators ¡V install mechanical or sand filtration devices within paved areas at the opening of storm inlets or prior to the discharge of concentrated flows into local streams.

5) Discouraging the Use of Toxic Fertilizers ¡V plant fertilizers, herbicides and pesticides are often washed away during rain events or via irrigation runoff. Instead, encourage the use of organic mulch and non-toxic products.

5.6.11.10 Treatment-control SUDS techniques are aimed at removing pollutants that have been washed up by the ¡§first-flush¡¨ of each rainfall event. Some examples under consideration at Tung Chung Valley roadways and development parcels include:

1) Rain Gardens ¡V shallow vegetated impoundments used to store and infiltrate runoff. Treatment occurs by infiltration through the soil matrix where pollutants are trapped in the soil. Treated stormwater is infiltrated to the native soil or discharged via perforated subdrain.

2) Infiltration Planters ¡V similar to rain gardens except constructed within a walled container such as a raised planter box or kerbed impoundment.

3) Permeable Pavements ¡V load-bearing surface that allows runoff to infiltrate through the surface. Treatment occurs by infiltration of runoff into the native soil or via perforated subdrain.

4) Green Roofs ¡V vegetated ¡§green¡¨ roofs can provide sustainable synergies, including improved insulation, reduction in surface runoff and increased biodiversity.

5) Rainwater Harvesting ¡V roof downspouts are diverted toward a localized storage tank where rainwater is treated and reused for non-potable uses like irrigation and toilet flushing.

Polder Scheme/ Stormwater Attenuation and Treatment Ponds

5.6.11.11 Due to the high ecological sensitivity of the Tung Chung Stream and the low-lying ground level along the banks of the east and west streams, a polder scheme is proposed to provide adequate flood protection to existing and proposed developments. Each development parcel within the polder scheme will contain a stormwater attenuation and treatment ponds to manage peak flows and remove pollutants. The treated runoff will be diverted back into Tung Chung Stream.The ponds will have a vegetated wetland zone and permanent pool during the wet season, which will create valuable open space amenity and increase biodiversity.

5.6.11.12 A diversion storage is proposed by installing several 1m diameter pipes below the proposed roadways and polder levees to offset the loss of flood storage volume at the Tung Chung Stream due to the proposed polder scheme. The pipes will serve dual purpose as the main gravity conveyance network during small rain events and as flood diversion storage from the east and west stream during large rainfall events. In the dry season, water quality deterioration due to stagnant situation in the stormwater attenuation and treatment ponds would be avoided with the implementation of suitable design measures, such as installation of subsurface drainage to eliminate areas of standing water, implementation of maintenance activities to remove any organic debris and to clear areas of stagnation etc., to be determined during detailed design stage to ensure compliance with the WPCO discharge standards. The conceptual layout of polder scheme is presented in Appendix 5.8.

5.6.11.13 It should be noted that for the sake of conservation, the water quality assessment has not included the effectiveness of the SUDS. The assessment results show that the water quality will still comply with WQO even for the worst case scenario.

Dry Weather Flow Interception (DWFI) at the Existing Villages

5.6.11.14 A new public sewerage system will be provided to serve the TCW development as well as to provide village sewers to the existing village areas (including Shek Mun Kap, Mok Ka, Nim Yuen, Lam Che, Ngau Au, Shek Lau Po, Ma Wan Chung and Wong Nai Uk). New sewers will be laid along existing and proposed roads, footways or drainage reserves.

5.6.11.15 According to TM-DSS, the effluent should not be discharged into the storm water drain. However, there may be illicit discharge to the drainage system from the village and the water quality of stormwater attenuation and treatment ponds in dry season would be deteriorated. In order to mitigate the risk of illicit connections of sewage flow to the drainage network, DWFI is proposed at the connection point of each village to the public drainage network. The interceptor will contain a penstock to divert and retain the very low flows to a nearby chamber for disposal to sewage treatment works or other disposal facility, by tankering away or other conveyance method approved by EPD.

5.6.12 Residual Impacts

5.6.12.1 No residual adverse water quality impact is anticipated in operational phase.

5.7 Conclusion

Construction Phase

5.7.1.1 While reclamation work in TCW has been removed to avoid water quality impacts as much as practicable, reclamation works at TCE is still required. Potential key sources of water quality impact during the construction phase include land formation works in TCE and Road P1; land improvement by deep cement mixing, construction of new seawall, stone column installation. It should be noted that potential construction phase water quality impacts associated with the proposed works have already been substantially reduced by the adoption of non-dredged reclamation methods for land formation and reclamation filling works within a leading seawall of about 200m. Other than reclamation works, the construction work in both TCE and TCW would involve construction site runoff and drainage; sewage effluent from construction workforce.

5.7.1.2 A quantitative assessment of potential water quality impacts associated with marine construction works has also been conducted, taking into account the critical periods for Suspended Sediment (SS) release. Other activities that could affect water quality during construction are primarily land-based and were assessed qualitatively.

5.7.1.3 Assessment results show that with the application of about 200m leading edge of partially completed seawall prior to marine filling activities and the implementation of mitigation measures (in the form of silt curtains and silt screens where applicable), there will be no exceedance of the SS criteria at any WSR due to project activities. However, when taking into account of the SS release from concurrent projects, cumulative exceedance is predicted at few WSRs near the Brothers Islands. Nevertheless, the exceedances are primarily due to the conservative assumptions for the concurrent projects rather than due to the contributions from the Tung Chung project. Those conservative assumptions are based on the maximum allowable SS release rates of the relevant concurrent project. However, based on the available information, the actual SS release rates are much lower than the maximum allowable release rates. Therefore, adverse residual water quality impacts due to the project are not anticipated.

5.7.1.4 A sensitivity scenario has also been conducted to address the potential shift in the implementation date of the 3RS. Results indicate that, given the separation between the 3RS and the Tung Chung New Town Extension, even under the worst case scenario, the construction of 3RS would not cause significant cumulative impacts on the water sensitive receivers in Tung Chung Bay, and vice versa, the construction activities in Tung Chung would also not cause significant water quality impacts on the sensitive receivers near the 3RS. By comparsion of the concurrent scenario and the above sensitivity scenario, exceedance at coral communities at the Brothers Islands is due to the conservative SS release assumption in concurrent projects. Non exceedance at Marine Parks of Brothers Islands is due to the hydrodynamics change without the landform of 3RS reclamation.

5.7.1.5 Other construction activities include bridge works at Tung Chung Stream, construction work of sewage pumping stations, fresh water and salt water reservoirs, water management facilities and polder scheme, proposed marina and groundwater and runoff for tunnel works. With the implementation of good site practices and the recommended mitigation measures to minimise potential water quality impacts, these construction activities, as well as general construction site drainage and sewage effluent from the construction workforce, are not anticipated to result in significant water quality impacts.

5.7.1.6 In view of the assessment findings, it is concluded that no adverse residual water quality impacts are anticipated during the construction phase of the project.

Operational Phase

5.7.1.7 The potential key sources of water quality impact during the operational phase include changes in hydrodynamics as a result of the reclaimed land in TCE and Road P1 and the increase of sewage amount and increase of pollution load from surface runoff.

5.7.1.8 For the reclamation in TCE and Road P1, quantitative assessments for ¡¥with project¡¦ and ¡¥without project¡¦ scenarios were undertaken for the assessment year of Year 2030 which represents the worst case for pollution loading, taking into account other planned and committed concurrent projects in the study area. The findings show that despite minor exceedances in total inorganic nitrogen (TIN) at some WSRs, these were attributed from the background concentration but not significantly attributed to the Project. On comparing the without project case and the existing monitoring data (Section 5.2.3), the exceedance is still exist. The predicted water quality in annual mean of depth averaged at the representative WSRs is summarized in below table. Therefore, implementation of the project would not result in adverse hydrodynamic and water quality changes in the study area.

5.7.1.9 The assessment has also demonstrated that the proposed reclamation works would not cause significant change in the water quality at the water sensitive receivers including the estuary of Tung Chung Stream and inside Tai O Bay.

5.7.1.10 In order to protect the water quality of Tung Chung Stream, Tai Ho Wan and other neighbouring water body, all the sewage pumping stations serving the TCE and TCW will be designed with appropriate design to avoid the need for emergency discharge. For the surface runoff from TCW, enhancement measures such as provision of stormwater attenuation and treatment ponds, dry weather flow interception at the existing villages have been recommended to protect the water quality in Tung Chung Stream.

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[1] Binnie Consultants Limited (1996). Fill Management Study - Phase IV Investigations and Development of Marine Borrow Areas: Coral Growth at High Island Dam. For The Civil Engineering Department, Hong Kong SAR Government.

[2] Meinhardt Infrastructure and Environment (2007). Contract P325 Environmental Assessment Services for Permanent Aviation Fuel Facility. Final Environmental Impact Assessment Report. Prepared for Airport Authority Hong Kong.

[3] Mouchel Asia Limited (2002). Environmental Assessment Study for Backfilling of Marine Borrow Pits at North of the Brothers (Agreement No Geo 01/2001) ¡V Environmental Assessment Report. For The Civil Engineering Department, Hong Kong SAR Government.

[4] Where C(x) = concentration at distance x from the source, q = sediment loss rate, D = water depth, x = distance from source, £s = diffusion velocity (=0.01 m/s).

[5] Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities (AEIAR-145/2009).

[6] Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road (AEIAR-144/2009).

[7] 132 KV Supply Circuit from Pui O via Chi Ma Wan Peninsula via Sea Crossing towards Cheung Chau (AEIAR-051/2002).

[8] Construction of an International Theme Park in Penny's Bay of North Lantau together with its Essential Associated Infrastructures - Environmental Impact Assessment (AEIAR-032/2000).

[9] Redfield A.C., On the proportions of organic derivations in seawater and their relation to the composition of plankton. In James Johnson Memorial Volume (ed. R.J. Daniel). University Press of Liverpool, pp.177-192, 1934.

[10] I. J. Hodgkiss & K. C. Ho (1997) Are changes in N:P ratios in coastal waters the key to increased red tide blooms? Hydrobiologia 352:141-147.