Chapter Title Page

U3.U UWater Quality Impact AssessmentU 3-1

U3.1U UIntroductionU 3-1

U3.2U UEnvironmental Legislation, Standards, Guidelines and CriteriaU 3-1

U3.3U UDescription of the EnvironmentU 3-7

U3.4U UWater Sensitive ReceiversU 3-15

U3.5U UAssessment MethodologyU 3-15

U3.6U UIdentification of Environmental ImpactU 3-22

U3.7U UPrediction and Evaluation of Environmental ImpactsU 3-25

U3.8U UMitigation of Adverse Environmental ImpactU 3-61

U3.9U UEvaluation of Residual ImpactsU 3-63

U3.10U UEnvironmental Monitoring and AuditU 3-63

U3.11U USummaryU 3-63

Tables

Table 3.1:__ Summary of Water Quality Objectives for Victoria Harbour WCZ_ 3-2

Table 3.2:__ Summary of Water Quality Objectives for Western Buffer WCZ_ 3-3

Table 3.3:__ Summary of Water Quality Objectives for Eastern Buffer WCZ_ 3-4

Table 3.4:__ WSD’s Water Quality Criteria for Flushing Water at Sea Water Intakes_ 3-5

Table 3.5:__ Marine Water Quality in Victoria Harbour Water Control Zone at Selected Stations in 2007_ 3-8

Table 3.6:__ Marine Water Quality in Eastern and Western Buffer Water Control Zones at Selected Stations in 2007_ 3-10

Table 3.7:__ Marine Water Quality in Victoria Harbour Water Control Zone at Selected Stations in 2008_ 3-12

Table 3.8:__ Marine Water Quality in Eastern and Western Buffer Water Control Zones at Selected Stations in 2008_ 3-14

Table 3.9:__ Marine Water Quality at To Kwa Wan and Shau Kei Wan Typhoon Shelters in 2007_ 3-16

Table 3.10:_ Bottom Sediment Quality at Selected Stations in 2003 – 2007_ 3-18

Table 3.11:_ Summary of Parameters for Sediment Plume Model (Delft3D-WAQ) 3-21

Table 3.12:_ Sediment Quality near the Dredging Area_ 3-22

Table 3.13:_ Maximum Production Rate for Scenario 1_ 3-25

Table 3.14:_ Maximum Production Rates for Scenario 2_ 3-26

Table 3.15:_ Depth-averaged and Surface SS levels near the Dredging Area_ 3-30

Table 3.16:_ DO, TIN and UIA levels near the Dredging Area_ 3-31

Table 3.17:_ Specifications for General Fill Material and Granular Fill Material 3-32

Table 3.18:_ Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 1A_ 3-34

Table 3.19:_ Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 1B_ 3-35

Table 3.20:_ Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 2A_ 3-36

Table 3.21:_ Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 2B_ 3-37

Table 3.22:_ Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 1A_ 3-38

Table 3.23:_ Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 1B_ 3-39

Table 3.24:_ Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 2A_ 3-40

Table 3.25:_ Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 2B_ 3-42

Table 3.26:_ Predicted Dissolved Oxygen Concentrations for Scenario 1A_ 3-45

Table 3.27:_ Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 1A_ 3-48

Table 3.28:_ Predicted Dissolved Oxygen Concentrations for Scenario 1B_ 3-51

Table 3.29:_ Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 1B_ 3-54

Table 3.30:_ Predicted Dissolved Oxygen Concentrations for Scenario 2A_ 3-58

Table 3.31:_ Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 2A_ 3-61

Table 3.32:_ Predicted Dissolved Oxygen Concentrations for Scenario 2B_ 3-64

Table 3.33:_ Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 2B_ 3-67

Table 3.34:_ Comparison of Marine Sediment Elutriate Test Results with Water Quality Standards_ 3-72

3. Water Quality Impact Assessment

3.1 Introduction

In accordance with the EIA Study Brief No. ESB-171/2007, water quality impact arising from the dredging, backfilling and other associated activities of the Project were assessed.

This section presents the findings of the assessment of potential water quality impacts associated with the construction and operation of the proposed submarine gas pipelines specifically in terms of the effects in the vicinity of sensitive receivers in accordance with the requirements of the Study Brief and Annexes 6 and 14 of the Technical Memorandum on the Environmental Impact Assessment Process. Suitable mitigation measures have been recommended to minimise potential adverse impacts and to ensure the acceptability of any residual impact (that is, after mitigation).

3.2 Environmental Legislation, Standards, Guidelines and Criteria

The criteria for evaluating water quality impacts in this EIA Study include:

¡ Technical Memorandum on Environmental Impact Assessment Process (Environmental Impact Assessment Ordinance) (EIAO-TM);

¡ Water Pollution Control Ordinance (WPCO);

¡ Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters (TM-DSS);

¡ Water Supplies Department (WSD) Water Quality Criteria; and

¡ Practice Note for Professional Persons (ProPECC), PN 1/94 “Construction Site Drainage”.

3.2.1 Environmental Impact Assessment Ordinance (EIAO)

The EIAO-TM was issued by the EPD under Section 16 of the EIAO. It specifies the assessment method and criteria that have been followed in this EIA Study.  Reference sections in the EIAO-TM provide the details of the assessment criteria and guidelines that are relevant to the water quality impact assessment, including:

¡ Annex 6 Criteria for Evaluating Water Pollution; and

¡ Annex 14 Guidelines for Assessment of Water Pollution.

3.2.2 Water Quality Objectives (WQOs)

The Water Pollution Control Ordinance (Cap. 358) provides the statutory framework for the protection and control of water quality in Hong Kong. According to the Ordinance and its subsidiary legislation, Hong Kong waters are divided into ten Water Control Zones (WCZs). Corresponding statements of WQOs are stipulated for different water regimes (marine waters, inland waters, bathing beaches subzones, secondary contact recreation subzones and fish culture subzones) in the WCZs based on their beneficial uses. The WQOs for the Victoria Harbour, Western Buffer and Eastern Buffer Water WCZs are listed in Table 3.1, Table 3.2 and Table 3.3 respectively. The locations of the aforesaid WCZs are shown in Figure 3.1.

Table 3.1: Summary of Water Quality Objectives for Victoria Harbour WCZ

Parameters	Objectives	Sub-Zone
Offensive Odour, Tints	Not to be present	Whole zone
Colour	Not to exceed 50 Hazen units, due to human activity	Inland waters
Visible foam, oil scum, litter	Not to be present	Whole zone
E. coli	Not to exceed 1000 per 100mL, calculated as the geometric mean of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days	Inland waters
Dissolved Oxygen (DO) within 2 m of the seabed	Not less than 2 mg L^-1 for 90% of the sampling occasions during the whole year	Marine waters
Depth-averaged DO	Not less than 4 mg L^-1 for 90% of the sampling occasions during the whole year; values should be calculated as the annual water column average (expressed normally as the arithmetic mean of at least 3 measurements at 1m below surface, mid depth and 1m above the seabed. However in water of a depth of 5m of less the mean shall be that of 2 measurements – 1m below surface and 1m above seabed, and in water of less than 3m the 1m below surface sample only shall apply.)	Marine waters
Dissolved Oxygen (DO)	Not less than 4 mg L^-1	Inland waters
pH	To be in the range of 6.5 - 8.5, change due to human activity not to exceed 0.2	Marine waters
Salinity	Change due to human activity not to exceed 10% of ambient	Whole zone
Temperature	Change due to human activity not to exceed 2 ^oC	Whole zone
Suspended Solids (SS)	Not to raise the ambient level by 30% caused by human activity	Marine waters
	Annual median not to exceed 25 mgL^-1 due to human activity	Inland waters
Unionised Ammonia (UIA)	Annual mean not to exceed 0.021 mg L^-1as unionised form	Whole zone
Nutrients	Shall not cause excessive algal growth	Marine waters
	Annual mean depth-averaged inorganic nitrogen not to exceed 0.4 mg L^-1	Marine waters
BOD5	Not to exceed 5 mg L^-1	Inland waters
	Not to exceed 30 mg L^-1	Inland waters
Toxic substances	Should not attain such levels as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or any other aquatic organisms.	Whole zone
	Human activity should not cause a risk to any beneficial use of the aquatic environment.	Whole zone

Source: Statement of Water Quality Objectives (Victoria Harbour (Phases One, Two and Three) Water Control Zone).

Table 3.2: Summary of Water Quality Objectives for Western Buffer WCZ

Parameters	Objectives	Sub-Zone
Offensive Odour, Tints	Not to be present	Whole zone
Colour	Not to exceed 30 Hazen units, due to human activity	Water gathering ground subzones
	Not to exceed 50 Hazen units, due to human activity	Other inland waters
Visible foam, oil scum, litter	Not to be present	Whole zone
E. coli	Not to exceed 610 per 100 mL, calculated as the geometric mean of all samples collected in a calendar year	Secondary contact recreation subzones and Fish culture subzones
	Not to exceed 180 per 100 mL, 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	Recreation subzones
	Less than 1 per 100 mL, calculated as the geometric mean of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days	Water gathering ground subzones
	Not to exceed 1000 per 100 mL, calculated as the geometric mean of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days	Other Inland waters
Depth-averaged Dissolved Oxygen (DO)	Not less than 4 mg L^-1for 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 1m below surface, mid-depth and 1m above seabed)	Marine waters except Fish culture subzones
	Not less than 5 mg L^-1 for 90% of the sampling occasions during the year; values should be calculated as water column average (arithmetic mean of at least 3 measurements at 1m below surface, mid-depth and 1m above seabed)	Fish culture subzones
Dissolved Oxygen (DO) within 2 m of the seabed	Not less than 2 mg L^-1 for 90% of the sampling occasions during the whole year	Marine waters and Fish culture subzones
Dissolved Oxygen (DO)	Not less than 4 mg L^-1	Water gathering ground subzones and other inland waters
pH	To be in the range of 6.5 - 8.5, change due to human activity not to exceed 0.2	Marine waters
	Not to exceed the range of 6.0 – 8.5 due to human activity	Water gathering ground subzones
	Not to exceed the range of 6.0 - 9.0 due to human activity	Other inland waters
Salinity	Change due to human activity not to exceed 10% of ambient	Whole zone
Temperature	Change due to human activity not to exceed 2 ^oC	Whole zone
Suspended Solids (SS)	Not to raise the ambient level by 30% caused by human activity and shall not accumulate to affect aquatic communities	Marine waters
	Annual median not to exceed 20 mg L^-1 due to human activity	Water gathering ground subzones
	Annual median not to exceed 25 mg L^-1 due to human activity	Other inland waters
Unionised ammonia (UIA)	Annual mean not to exceed 0.021 mg L^-1 as unionised form	Whole zone
Nutrients	Shall not cause excessive algal growth	Marine waters
	Annual mean depth-averaged inorganic nitrogen not to exceed 0.4 mg L^-1	Marine waters
5-day biochemical oxygen demand (BOD5)	Not to exceed 3 mg L^-1	Water gathering ground subzones
	Not to exceed 5 mg L^-1	Other inland waters
Chemical Oxygen Demand (COD)	Not to exceed 15 mg L^-1	Water gathering ground subzones
	Not to exceed 30 mg L^-1	Other inland waters
Toxic substances	Should not attain such levels as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or any other aquatic organisms.	Whole zone
	Human activity should not cause a risk to any beneficial use of the aquatic environment.	Whole zone

Source: Statement of Water Quality Objectives (Western Buffer Water Control Zone).

Table 3.3: Summary of Water Quality Objectives for Eastern Buffer WCZ

Parameters	Objectives	Sub-Zone
Offensive Odour, Tints	Not to be present	Whole zone
Visible foam, oil scum, litter	Not to be present	Whole zone
Dissolved oxygen (DO) within 2m of the seabed	Not less than 2 mg L^-1 for 90% of the sampling occasions during the whole year	Marine waters and Fish culture subzones
Depth-averaged DO	Not less than 4 mg L^-1 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 1m below surface, mid-depth and 1m above seabed)	Marine waters excepting fish culture subzones
	Not less than 5 mg L^-1 for 90% of the sampling occasions during the year; values should be calculated as water column average (arithmetic mean of at least 3 measurements at 1m below surface, mid-depth and 1m above seabed)	Fish culture subzones
	Not less than 4 mg L^-1	Water gathering ground subzone and other inland waters
5-day biochemical oxygen demand (BOD5)	Not to exceed 3 mg L^-1	Water gathering ground subzones
	Not to exceed 5 mg L^-1	Other inland waters
Chemical oxygen demand (COD)	Not to exceed 15 mg L^-1	Water gathering ground subzones
	Not to exceed 30 mg L^-1	Other inland waters
pH	To be in the range of 6.5 – 8.5, change due to human activity not to exceed 0.2	Marine waters
	To be in the range of 6.5 – 8.5	Water gathering ground subzones
	To be in the range of 6.0 – 9.0	Other inland waters
Salinity	Change due to waste discharges not to exceed 10% of ambient	Whole zone
Temperature	Change due to waste discharges not to exceed 2 ^oC	Whole zone
Suspended solids (SS)	Not to raise the ambient level by 30% caused by human activity and shall not accumulate to affect aquatic communities	Marine waters
	Change due to human activity not to exceed 20 mg L^-1 of annual median	Water gathering ground subzones
	Change due to human activity not to exceed 25 mg L^-1 of annual median	Other inland waters
Unionized ammonia (UIA)	Annual mean not to exceed 0.021mg L^-1 as unionized form	Whole zone
Nutrients	Shall not cause excessive algal growth	Marine waters
	Annual mean depth-averaged inorganic nitrogen not to exceed 0.4 mg L^-1	Marine waters
Toxic substances	Should not attain such levels as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or any other aquatic organisms.	Whole zone
	Human activity should not cause a risk to any beneficial use of the aquatic environment	Whole zone
E. coli	Not exceed 610 per 100mL, calculated as the geometric mean of all samples collected in one calendar year	Fish culture subzones
	Less than 1 per 100mL, calculated as the geometric mean of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days	Water gathering ground subzones
	Not exceed 1000 per 100mL, calculated as the geometric mean of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days	Other inland waters
Colour	Change due to human activity not to exceed 30 Hazen units	Water gathering ground
	Change due to human activity not to exceed 50 Hazen units	Other inland waters

Source: Statement of Water Quality Objectives (Eastern Buffer Water Control Zone).

3.2.3 Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters (TM-DSS)

The WPCO also controls effluent discharging into the WCZ through a licensing system. A Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters (TM-DSS) was issued under Section 21 of the WPCO that gives guidance on the permissible effluent discharges based on the type of receiving waters (foul sewers, storm water drains, inland and coastal waters). The limits control the physical, chemical and microbial quality of effluents. Sewage from the proposed construction activities should comply with the standards for effluent discharged into the foul sewers, inshore waters or marine waters of the Victoria Harbour WCZ, as given in the TM-DSS.

3.2.4 Water Supplies Department (WSD) Water Quality Criteria

Besides the WQOs set under the WPCO, WSD has specified a set of water quality objectives for water quality at flushing water intakes as shown in Table 3.4.

Table 3.4: WSD’s Water Quality Criteria for Flushing Water at Sea Water Intakes

Parameter (in mg/L unless otherwise stated)	Target Limit
Colour (HU)	< 20
Turbidity (NTU)	< 10
Threshold Odour Number (odour unit)	< 100
Ammonia Nitrogen (NH3-N)	< 1
Suspended Solids (SS)	< 10
Dissolved Oxygen (DO)	> 2
5-day Biochemical Oxygen Demand (BOD5)	< 10
Synthetic Detergents	< 5
E. coli (no. per 100 mL)	< 20,000

3.2.5 Cooling Water Intakes Water Quality Criteria

Based on a questionnaire survey conducted under the approved Comprehensive Feasibility Study for Wan Chai Development Phase II (CFSWDII) EIAF[1]F, a SS limit of 40mg/l was adopted as the assessment criterion for MTRC South Intake.  No information on the SS limit is available for other cooling water intakes.  These findings have been confirmed by a telephone survey conducted under the recent approved EIA for the Hong Kong Convention and Exhibition Centre (HKCEC) Atrium Link Extension (ALE) and further verified by a questionnaire survey conducted under another recent approved EIA for the Dredging Works for Proposed Cruise Terminal at Kai Tak.

3.2.6 Practice Note for Professional Persons (ProPECC) PN/94 “Construction Site Drainage”

A practice note for professional persons was issued by the EPD to provide guidelines for handling and disposal of construction site discharges. The ProPECC PN 1/94 “Construction Site Drainage” provides good practice guidelines for dealing with ten types of discharge from a construction site. These include surface runoff, groundwater, boring and drilling water, bentonite slurry, water for testing and sterilisation of water retaining structures and water pipes, wastewater from building construction, acid cleaning, etching and pickling wastewater, and wastewater from site facilities. Practices given in the ProPECC PN 1/94 should be followed as far as possible during construction to minimise the water quality impact due to construction activities.

3.2.7 Suspended Solids Criterion for Benthic Organisms

Benthic organisms, including corals, may be damaged by sediment deposition that blocks the respiratory and feeding organs of the corals. According to Hawker and ConnellF[2]F, the sedimentation rate higher than 0.1 kg m^-2 per day would introduce moderate to severe impact upon corals. This criterion has been adopted for protecting the corals in Hong Kong under other approved EIA study such as Western Cross Harbour Main EIAF[3]F and was adopted as the assessment criterion for protecting the marine ecological sensitive receivers in this study. This sedimentation rate criterion is considered to offer sufficient protection to marine ecological sensitive receivers and is anticipated to guard against unacceptable impacts. There are no established legislative criteria for water quality for corals. An elevation criterion of less than 30% of ambient baseline conditions has been adopted as the critical value above which impacts to the habitat may occur, same as the previous approved EIA F[4]F for assessing SS impacts on corals in Victoria Harbour.

The above assessment criteria would be used to assess water quality impact to coral habitats (i.e. the far field ecological sensitive receivers) as identified and indicated in Figure 3.2. As discussed in Section 3.4.2, the isolated coral colonies found in the Kai Tak area are not considered as sensitive coral site and are therefore not covered in this water quality impact assessment. The ecological impact to the isolated coral colonies will be addressed and assessed in Section 5.

3.2.8 Suspended Solids Criterion for Fish Culture Zone

The WQO for SS as referred to in Section 3.2.2 was adopted for assessing SS impacts on fish culture zones.

3.2.9 Sediment Quality

Dredged sediments destined for marine disposal are classified according to a set of regulatory guidelines with sediment quality criteria, which include organic pollutants and other toxic substances, for designation of sediments (Management of Dredged/Excavated Sediment, ETWB TCW No. 34/2002). Details on marine dredged sediment quality are presented in Section 4.

The requirements for the marine disposal of sediment is specified in the ETWB TCW No. 34/2002. Marine disposal of dredged materials is controlled under the Dumping at Sea Ordinance.

3.3 Description of the Environment

3.3.1 Marine Water Quality Monitored by EPD

The marine water quality monitoring data routinely collected by EPD in the Victoria Harbour were used to establish the baseline condition. A summary of water quality data for selected EPD monitoring stations extracted from EPD’s publication “Marine Water Quality in Hong Kong 2007” and “Marine Water Quality in Hong Kong 2008” is presented in Table 3.5 and Table 3.6 for the Victoria Harbour (VM1, 2, 4, 5, 6, 7, 8 and 15), Eastern Buffer (EM1 and 2) and Western Buffer (WM2 and 3) WCZs. Locations of the monitoring stations are shown in Figure 3.2.

Table 3.5: Marine Water Quality in Victoria Harbour Water Control Zone at Selected Stations in 2007

Parameter		Victoria Harbour East		Victoria Harbour Central			Victoria Harbour West		Stonecutters Island	WPCO WQO (in marine waters)
		VM1	VM2	VM4	VM5	VM6	VM7	VM8	VM15
Temperature (°C)		22.5 (17.1 – 27.8)	22.9 (17.2 – 27.8)	23.0 (17.2 – 27.9)	23.0 (17.2 – 28.0)	23.0 (17.4 – 27.9)	23.3 (17.4 – 27.8)	23.3 (17.4 – 27.7)	23.2 (17.3 – 27.9)	Not more than 2°C in daily temperature range
Salinity		32.7 (31.7 – 33.9)	32.2 (30.1 – 33.6)	32.0 (29.3 – 33.8)	31.9 (29.3 – 33.5)	32.0 (28.8 – 33.5)	31.5 (26.4 – 33.4)	31.7 (26.4 – 33.5)	31.7 (28.1 – 33.5)	Not to cause more than 10% change
Dissolved Oxygen (DO) (% Saturation)	Depth average	80 (55 – 99)	79 (52 – 97)	76 (57 – 95)	71 (57 – 87)	70 (53 – 94)	71 (58 – 89)	77 (58 – 109)	74 (55 – 90)	Not available
	Bottom	77 (51 – 99)	72 (38 – 97)	70 (33 – 94)	64 (30 – 96)	67 (42 – 95)	66 (30 – 89)	73 (19 – 110)	68 (38 – 91)	Not available
Dissolved Oxygen (DO) (mg/l)	Depth average	5.7 (3.9 – 7.7)	5.6 (3.6 – 7.5)	5.4 (4.0 – 7.2)	5.1 (3.8 – 6.9)	5.0 (3.5 – 7.3)	5.0 (3.8 – 7.0)	5.5 (4.0 – 8.6)	5.3 (3.7 – 7.0)	Not less than 4mg/l for 90% of the samples
	Bottom	5.6 (3.6 – 7.7)	5.2 (2.7 – 7.6)	5.1 (2.3 – 7.3)	4.6 (2.1 – 7.4)	4.8 (3.0 – 7.4)	4.7 (2.1 – 7.0)	5.2 (1.3 – 8.6)	4.9 (2.6 – 7.0)	Not less than 2mg/l for 90% of the samples
pH		7.9 (6.0 – 8.2)	8.0 (7.7 – 8.3)	8.0 (7.7 – 8.2)	8.0 (7.7 – 8.2)	8.0 (7.7 – 8.3)	8.0 (7.6 – 8.5)	8.0 (7.6 – 8.5)	8.0 (7.7 – 8.4)	6.5 – 8.5 (±0.2 from natural range)
Secchi disc Depth (m)		2.3 (1.0 – 3.5)	2.2 (1.5 – 2.8)	2.2 (1.6 – 3.5)	1.9 (1.5 – 2.4)	2.0 (1.4 – 2.6)	1.9 (0.9 – 2.5)	2.0 (1.2 – 3.0)	2.0 (1.7 – 2.5)	Not available
Turbidity (NTU)		12.0 (4.3 – 33.1)	11.1 (4.3 – 24.4)	10.8 (4.3 – 21.1)	11.1 (4.2 – 23.4)	10.9 (4.2 – 18.3)	10.8 (4.2 – 16.1)	13.8 (4.1 – 34.8)	11.9 (4.1 – 23.0)	Not available
Suspended Solids (SS) (mg/l)		4.2 (1.6 – 7.0)	3.5 (1.8 – 6.0)	3.9 (2.4 – 6.0)	4.1 (1.5 – 11.1)	4.8 (1.7 – 16.2)	4.7 (1.3 – 11.7)	6.6 (3.1 – 11.6)	6.7 (2.8 – 15.3)	Not more than 30% increase
5-day Biochemical Oxygen Demand (BOD5) (mg/l)		0.9 (0.6 – 1.6)	1.2 (0.5 – 2.6)	1.0 (0.4 – 2.1)	1.5 (0.2 – 2.3)	1.3 (0.7 – 2.1)	1.0 (0.4 – 2.2)	0.9 (0.3 – 1.9)	1.3 (0.6 – 2.1)	Not available
Nitrite Nitrogen (NO2-N) (mg/l)		0.023 (0.007 – 0.057)	0.028 (0.009 – 0.089)	0.030 (0.011 – 0.111)	0.035 (0.015 – 0.108)	0.034 (0.016 – 0.082)	0.037 (0.011 – 0.120)	0.039 (0.004 – 0.122)	0.039 (0.017 – 0.123)	Not available
Nitrate Nitrogen (NO3-N) (mg/l)		0.092 (0.036 – 0.220)	0.110 (0.043 – 0.273)	0.124 (0.047 – 0.333)	0.141 (0.060 – 0.333)	0.133 (0.060 – 0.257)	0.154 (0.039 – 0.330)	0.138 (0.026 – 0.307)	0.146 (0.070 – 0.370)	Not available
Ammonia Nitrogen (NH3-N) (mg/l)		0.09 (0.03 – 0.14)	0.12 (0.03 – 0.21)	0.14 (0.04 – 0.21)	0.18 (0.07 – 0.29)	0.20 (0.06 – 0.32)	0.21 (0.12 – 0.28)	0.19 (0.07 – 0.31)	0.20 (0.07 – 0.32)	Not available
Unionised Ammonia (UIA) (mg/l)		0.003 (<0.001–0.007)	0.005 (<0.001–0.009)	0.006 (<0.001–0.009)	0.007 (0.001–0.012)	0.007 (0.001–0.012)	0.009 (0.002 – 0.016)	0.008 (0.003 – 0.014)	0.008 (0.001 – 0.012)	Not more than 0.021 mg/l for annual mean
Total Inorganic Nitrogen (TIN) (mg/l)		0.20 (0.08 – 0.38)	0.26 (0.09 – 0.52)	0.29 (0.10 – 0.63)	0.36 (0.14 – 0.60)	0.36 (0.14 – 0.57)	0.41 (0.25 – 0.55)	0.37 (0.15 – 0.68)	0.38 (0.15 – 0.65)	Not more than 0.4 mg/l for annual mean
Total Nitrogen (TN) (mg/l)		0.35 (0.23 – 0.51)	0.46 (0.24 – 0.66)	0.49 (0.28 – 0.75)	0.59 (0.42 – 0.80)	0.58 (0.37 – 0.76)	0.61 (0.37 – 0.80)	0.54 (0.34 – 0.95)	0.60 (0.37 – 0.77)	Not available
Orthophosphate Phosphorus (PO4) (mg/l)		0.02 (0.009 – 0.044)	0.03 (0.010 – 0.049)	0.03 (0.005 – 0.053)	0.04 (0.015 – 0.062)	0.04 (0.015 – 0.060)	0.040 (0.022 – 0.060)	0.032 (0.019 – 0.059)	0.038 (0.014 – 0.059)	Not available
Total Phosphorus (TP) (mg/l)		0.04 (0.03 – 0.06)	0.05 (0.03 – 0.07)	0.05 (0.04 – 0.07)	0.06 (0.05 – 0.09)	0.06 (0.05 – 0.08)	0.07 (0.05 – 0.11)	0.05 (0.04 – 0.08)	0.06 (0.05 – 0.08)	Not available
Chlorophyll-a (µg/l)		4.3 (0.8 – 17.8)	6.4 (0.7 – 36.0)	6.6 (0.5 – 41.7)	5.9 (0.7 – 30.8)	4.8 (0.6 – 22.6)	2.8 (0.5 – 9.5)	2.9 (0.7 – 10.1)	6.2 (0.6 – 27.2)	Not available
E. coli (cfu/100ml)		320 (90 – 1800)	1900 (210 – 47000)	1400 (430 – 13000)	6000 (640 – 29000)	4600 (1100 – 26000)	6000 (700 – 21000)	5400 (900 – 25000)	1600 (300 – 4700)	Not available
Faecal Coliforms (cfu/100ml)		870 (230 – 5100)	4200 (550 – 68000)	3500 (1100 – 34000)	16000 (2600 – 61000)	12000 (2600 – 54000)	19000 (3100 – 81000)	14000 (3400 – 57000)	4500 (650 – 16000)	Not available

Note:

1. Except as specified, data presented are depth-averaged values calculated by taking the means of three depths: Surface, mid-depth, bottom.

2. Data presented are annual arithmetic means of depth-averaged results except for E. coli and faecal coliforms that are annual geometric means.

3. Data enclosed in brackets indicate the ranges.

4. Shaded cells indicate non-compliance with the WQOs.

(Source: Adopted from EPD Marine Water Quality Hong Kong in 2007)

Table 3.6: Marine Water Quality in Eastern and Western Buffer Water Control Zones at Selected Stations in 2007

Parameter		Eastern Buffer WCZ			Western Buffer WCZ
		EM1	EM2	WPCO WQO (in marine waters)	WM2	WM3	WPCO WQO (in marine waters)
Temperature (°C)		22.8 (17.1 – 27.8)	22.9 (17.0 – 27.8)	Not more than 2°C in daily temperature range	23.3 (17.4 – 27.7)	23.1 (17.3 – 27.7)	Not more than 2°C in daily temperature range
Salinity		32.9 (31.7 – 34.0)	32.9 (31.8 – 34.1)	Not to cause more than 10% change	31.6 (26.7 – 33.7)	32.2 (29.6 – 33.7)	Not to cause more than 10% change
Dissolved Oxygen (DO) (% Saturation)	Depth average	80 (59 – 101)	84 (70 – 102)	Not available	80 (63 – 113)	76 (55 – 111)	Not available
	Bottom	77 (43 – 102)	78 (44 – 103)	Not available	76 (34 – 112)	75 (36 – 109)	Not available
Dissolved Oxygen (DO) (mg/l)	Depth average	5.7 (4.0 – 8.0)	6.0 (4.7 – 8.1)	Not less than 4mg/l for 90% of the samples	5.73 (4.4 – 8.9)	5.42 (3.8 – 8.7)	Not less than 4mg/l for 90% of the samples
	Bottom	5.5 (3.1 – 8.1)	5.6 (3.2 – 8.2)	Not less than 2mg/l for 90% of the samples	5.5 (2.3 – 8.8)	5.39 (2.5 – 8.6)	Not less than 2mg/l for 90% of the samples
pH		8.1 (7.8 – 8.3)	8.1 (7.7 – 8.3)	6.5 – 8.5 (±0.2 from natural range)	8.0 (7.5 – 8.5)	8.0 (7.3 – 8.5)	6.5 – 8.5 (±0.2 from natural range)
Secchi disc Depth (m)		2.2 (1.8 – 3.0)	2.1 (1.5 – 2.5)	Not available	1.9 (1.4 – 2.5)	1.8 (1.0 – 3.5)	Not available
Turbidity (NTU)		15.2 (6.6 – 65.2)	18.1 (4.9 – 99.2)	Not available	14.5 (4.4 – 43.6)	12.1 (4.2 – 17.4)	Not available
Suspended Solids (SS) (mg/l)		4.0 (1.5 – 12.8)	4.2 (1.5 – 14.3)	Not more than 30% increase	5.9 (3.3 – 9.8)	6.0 (3.3 – 12.1)	Not more than 30% increase
5-day Biochemical Oxygen Demand (BOD5) (mg/l)		0.8 (0.2 – 1.8)	0.9 (0.2 – 1.8)	Not available	0.69 (0.1 – 1.7)	0.8 (0.2 – 2.2)	Not available
Nitrite Nitrogen (NO2-N) (mg/l)		0.014 (0.002 – 0.022)	0.013 (0.002 – 0.021)	Not available	0.045 (0.005 – 0.163)	0.037 (0.006 – 0.103)	Not available
Nitrate Nitrogen (NO3-N) (mg/l)		0.074 (0.009 – 0.200)	0.067 (0.009 – 0.187)	Not available	0.152 (0.030 – 0.363)	0.123 (0.035 – 0.243)	Not available
Ammonia Nitrogen (NH3-N) (mg/l)		0.07 (0.04 – 0.10)	0.05 (0.03 – 0.08)	Not available	0.13 (0.06 – 0.22)	0.16 (0.06 – 0.27)	Not available
Unionised Ammonia (UIA) (mg/l)		0.003 (0.001 – 0.005)	0.003 (0.001 – 0.005)	Not more than 0.021 mg/l for annual mean	0.006 (0.002 – 0.012)	0.006 (0.002 – 0.012)	Not more than 0.021 mg/l for annual mean
Total Inorganic Nitrogen (TIN) (mg/l)		0.15 (0.05 – 0.32)	0.13 (0.05 – 0.27)	Not more than 0.4 mg/l for annual mean	0.32 (0.14 – 0.59)	0.32 (0.19 – 0.49)	Not more than 0.4 mg/l for annual mean
Total Nitrogen (TN) (mg/l)		0.29 (0.14 – 0.49)	0.27 (0.14 – 0.42)	Not available	0.48 (0.29 – 0.72)	0.47 (0.31 – 0.67)	Not available
Orthophosphate Phosphorus (PO4) (mg/l)		0.016 (0.006 – 0.038)	0.014 (0.005 – 0.031)	Not available	0.025 (0.015 – 0.048)	0.028 (0.017 – 0.047)	Not available
Total Phosphorus (TP) (mg/l)		0.03 (0.02 – 0.06)	0.03 (0.02 – 0.05)	Not available	0.04 (0.03 – 0.07)	0.05 (0.03 – 0.07)	Not available
Chlorophyll-a (µg/l)		3.5 (1.0 – 10.8)	3.2 (0.7 – 6.7)	Not available	3.0 (0.3 – 11.0)	2.3 (0.3 – 8.6)	Not available
E. coli (cfu/100ml)		110 (5 – 570)	49 (4 – 190)	Not available	960 (12 – 5900)	3800 (490 – 30000)	Not available
Faecal Coliforms (cfu/100ml)		310 (15 – 1500)	140 (24 – 650)	Not available	2100 (38 – 19000)	11000 (840 - 110000)	Not available

Note:

1. Except as specified, data presented are depth-averaged values calculated by taking the means of three depths: Surface, mid-depth, bottom.

2. Data presented are annual arithmetic means of depth-averaged results except for E. coli and faecal coliforms that are annual geometric means.

3. Data enclosed in brackets indicate the ranges.

4. Shaded cells indicate non-compliance with the WQOs.

(Source: Adopted from EPD Marine Water Quality Hong Kong in 2007)

Table 3.7: Marine Water Quality in Victoria Harbour Water Control Zone at Selected Stations in 2008

Parameter		Victoria Harbour East		Victoria Harbour Central			Victoria Harbour West		Stonecutters Island	WPCO WQO (in marine waters)
		VM1	VM2	VM4	VM5	VM6	VM7	VM8	VM15
Temperature (°C)		23.1 (16.1 – 27.2)	23.4 (16.2 – 27.3)	23.4 (16.2 – 27.1)	23.5 (16.3 – 27.2)	23.5 (16.3 – 27.2)	22.7 (14.8 – 27.8)	22.6 (14.7 – 27.6)	23.6 (16.5 – 27.2)	Not more than 2°C in daily temperature range
Salinity		32.0 (29.3 – 33.5)	31.4 (26.3 – 33.2)	31.3 (26.2 – 33.2)	30.9 (25.7 – 32.7)	30.9 (27.1 – 32.7)	31.0 (26.8 – 33.2)	31.1 (27.1 – 33.2)	30.6 (24.0 – 32.8)	Not to cause more than 10% change
Dissolved Oxygen (DO) (% Saturation)	Depth average	77 (45 – 92)	76 (46 – 97)	73 (45 – 94)	70 (45 – 89)	72 (42 – 103)	74 (45 – 95)	80 (58 – 94)	73 (44 – 91)	Not available
	Bottom	75 (39 – 90)	75 (43 – 90)	69 (35 – 87)	69 (45 – 85)	67 (36 – 82)	72 (40 – 95)	78 (52 – 98)	68 (32 – 83)	Not available
Dissolved Oxygen (DO) (mg/l)	Depth average	5.5 (3.1 – 7.1)	5.4 (3.2 – 7.1)	5.3 (3.0 – 7.0)	5.0 (3.0 – 6.2)	5.1 (2.8 – 7.1)	5.4 (3.0 – 7.8)	5.8 (3.9 – 7.7)	5.2 (2.9 – 6.3)	Not less than 4mg/l for 90% of the samples
	Bottom	5.4 (2.7 – 7.2)	5.3 (3.0 – 7.0)	4.9 (2.4 – 7.0)	5.0 (3.0 – 6.8)	4.8 (2.5 – 6.6)	5.3 (2.7 – 7.8)	5.7 (3.5 – 8.1)	4.9 (2.3 – 6.2)	Not less than 2mg/l for 90% of the samples
pH		8.1 (7.9 – 8.3)	8.1 (7.9 – 8.3)	8.0 (7.9 – 8.3)	8.0 (7.9 – 8.3)	8.0 (7.8 – 8.3)	8.0 (7.7 – 8.2)	8.1 (7.9 – 8.2)	8.0 (7.8 – 8.3)	6.5 – 8.5 (±0.2 from natural range)
Secchi disc Depth (m)		2.6 (1.8 – 3.2)	2.6 (1.8 – 3.2)	2.5 (1.5 – 3.1)	2.3 (1.8 – 3.3)	2.4 (1.3 – 3.1)	2.4 (1.5 – 3.0)	2.3 (1.0 – 3.6)	2.3 (1.6 – 3.2)	Not available
Turbidity (NTU)		8.9 (2.9 – 18.6)	7.4 (2.5 – 11.3)	7.9 (2.6 – 11.9)	7.9 (3.1 – 12.0)	8.1 (3.5 – 11.2)	8.4 (4.3 – 11.8)	8.9 (3.9 – 12.8)	9.0 (5.0 – 11.9)	Not available
Suspended Solids (SS) (mg/l)		6.2 (1.7 – 13.7)	3.9 (1.9 – 7.5)	5.1 (2.9 – 8.6)	5.0 (2.8 – 8.7)	5.3 (2.7 – 7.3)	4.6 (2.1 – 6.8)	5.0 (2.7 – 8.6)	6.1 (2.8 – 9.2)	Not more than 30% increase
5-day Biochemical Oxygen Demand (BOD5) (mg/l)		0.6 (0.3 – 0.8)	0.7 (0.3 – 1.1)	0.8 (0.3 – 1.4)	1.2 (0.3 – 3.5)	0.8 (0.3 – 1.3)	0.8 (0.2 – 1.5)	0.7 (0.1 – 1.5)	0.8 (0.3 – 1.3)	Not available
Nitrite Nitrogen (NO2-N) (mg/l)		0.024 (0.006 – 0.098)	0.032 (0.009 – 0.140)	0.035 (0.008 – 0.152)	0.039 (0.020 – 0.146)	0.038 (0.019 – 0.133)	0.040 (0.009 – 0.060)	0.041 (0.008 – 0.094)	0.043 (0.021 – 0.177)	Not available
Nitrate Nitrogen (NO3-N) (mg/l)		0.111 (0.037 – 0.247)	0.146 (0.056 – 0.433)	0.156 (0.047 – 0.450)	0.176 (0.098 – 0.447)	0.168 (0.099 – 0.363)	0.173 (0.049 – 0.310)	0.166 (0.047 – 0.287)	0.182 (0.084 – 0.540)	Not available
Ammonia Nitrogen (NH3-N) (mg/l)		0.08 (0.03 – 0.13)	0.12 (0.03 – 0.18)	0.13 (0.03 – 0.22)	0.17 (0.05 – 0.27)	0.17 (0.07 – 0.29)	0.19 (0.12 – 0.28)	0.15 (0.04 – 0.25)	0.19 (0.12 – 0.31)	Not available
Unionised Ammonia (UIA) (mg/l)		0.004 (<0.001 – 0.006)	0.006 (<0.001 – 0.012)	0.006 (<0.001 – 0.011)	0.007 (0.001 – 0.010)	0.007 (0.002 – 0.011)	0.008 (0.002 – 0.015)	0.007 (0.001 – 0.013)	0.008 (0.003 – 0.014)	Not more than 0.021 mg/l for annual mean
Total Inorganic Nitrogen (TIN) (mg/l)		0.22 (0.11 – 0.42)	0.30 (0.14 – 0.71)	0.32 (0.15 – 0.73)	0.39 (0.22 – 0.71)	0.38 (0.21 – 0.62)	0.40 (0.21 – 0.57)	0.35 (0.22 – 0.51)	0.42 (0.25 – 0.87)	Not more than 0.4 mg/l for annual mean
Total Nitrogen (TN) (mg/l)		0.38 (0.22 – 0.56)	0.48 (0.28 – 0.93)	0.52 (0.26 – 0.96)	0.62 (0.40 – 0.93)	0.58 (0.46 – 0.81)	0.63 (0.34 – 0.)	0.53 (0.34 – 0.69)	0.62 (0.46 – 1.09)	Not available
Orthophosphate Phosphorus (PO4) (mg/l)		0.020 (0.009 – 0.032)	0.026 (0.008 – 0.040)	0.028 (0.008 – 0.041)	0.032 (0.009 – 0.057)	0.032 (0.007 – 0.048)	0.036 (0.020 – 0.053)	0.028 (0.013 – 0.040)	0.033 (0.010 – 0.049)	Not available
Total Phosphorus (TP) (mg/l)		0.03 (0.02 – 0.04)	0.04 (0.02 – 0.06)	0.04 (0.02 – 0.06)	0.05 (0.04 – 0.09)	0.05 (0.03 – 0.07)	0.05 (0.03 – 0.07)	0.04 (0.03 – 0.06)	0.05 (0.03 – 0.07)	Not available
Chlorophyll-a (µg/l)		2.7 (0.4 – 11.3)	3.7 (0.4 – 18.3)	3.5 (0.2 – 18.3)	3.9 (0.3 – 19.3)	3.8 (0.5 – 24.0)	1.8 (0.6 – 3.2)	1.8 (1.0 – 2.9)	4.2 (0.4 – 20.7)	Not available
E. coli (cfu/100ml)		330 (76 – 3800)	1100 (76 – 14000)	2900 (370 – 12000)	4200 (840 – 23000)	4500 (990 – 12000)	5100 (290 – 41000)	4300 (410 – 21000)	2300 (440 – 9000)	Not available
Faecal Coliforms (cfu/100ml)		750 (110 – 11000)	2500 (95 – 26000)	6300 (920 – 26000)	10000 (1400 – 81000)	11000 (1900 - 37000)	13000 (1100 – 140000)	10000 (1100 – 76000)	6100 (800 - 23000)	Not available

Note:

1. Except as specified, data presented are depth-averaged values calculated by taking the means of three depths: Surface, mid-depth, bottom.

2. Data presented are annual arithmetic means of depth-averaged results except for E. coli and faecal coliforms that are annual geometric means.

3. Data enclosed in brackets indicate the ranges.

4. Shaded cells indicate non-compliance with the WQOs.

(Source: Adopted from EPD Marine Water Quality Hong Kong in 2008)

Table 3.8: Marine Water Quality in Eastern and Western Buffer Water Control Zones at Selected Stations in 2008

Parameter		Eastern Buffer WCZ			Western Buffer WCZ
		EM1	EM2	WPCO WQO (in marine waters)	WM2	WM3	WPCO WQO (in marine waters)
Temperature (°C)		23.1 (16.0 – 27.0)	23.1 (15.9 – 27.0)	Not more than 2°C in daily temperature range	22.6 (14.7 – 27.6)	22.6 (14.7 – 27.5)	Not more than 2°C in daily temperature range
Salinity		32.5 (31.0 – 33.6)	32.6 (30.8 – 33.6)	Not to cause more than 10% change	30.9 (26.4 – 33.2)	31.3 (27.7 – 33.2)	Not to cause more than 10% change
Dissolved Oxygen (DO) (% Saturation)	Depth average	81 (49 – 96)	83 (56 – 95)	Not available	82 (52 – 101)	80 (51 – 99)	Not available
	Bottom	81 (52 – 93)	82 (53 – 96)	Not available	80 (48 – 103)	78 (40 – 103)	Not available
Dissolved Oxygen (DO) (mg/l)	Depth average	5.8 (3.4 – 7.2)	5.9 (3.9 – 7.1)	Not less than 4mg/l for 90% of the samples	6.0 (3.4 – 8.3)	5.8 (3.4 – 8.2)	Not less than 4mg/l for 90% of the samples
	Bottom	5.8 (3.6 – 7.2)	5.9 (3.7 – 7.3)	Not less than 2mg/l for 90% of the samples	5.8 (3.3 – 8.5)	5.7 (2.7 – 8.4)	Not less than 2mg/l for 90% of the samples
pH		8.1 (8.0 – 8.3)	8.2 (8.0 – 8.3)	6.5 – 8.5 (±0.2 from natural range)	8.1 (7.8 – 8.2)	8.1 (7.9 – 8.2)	6.5 – 8.5 (±0.2 from natural range)
Secchi disc Depth (m)		2.4 (1.8 – 3.0)	2.5 (1.7 – 3.0)	Not available	2.5 (1.0 – 4.0)	2.1 (1.0 – 3.0)	Not available
Turbidity (NTU)		8.6 (3.2 – 16.5)	8.4 (3.4 – 14.5)	Not available	8.6 (3.6 – 14.1)	9.4 (5.6 – 14.0)	Not available
Suspended Solids (SS) (mg/l)		4.4 (1.7 – 13.2)	4.2 (2.1 – 8.3)	Not more than 30% increase	4.8 (2.8 – 7.6)	5.7 (3.0 – 8.7)	Not more than 30% increase
5-day Biochemical Oxygen Demand (BOD5) (mg/l)		0.7 (0.4 – 1.6)	0.7 (0.2 – 1.6)	Not available	0.7 (0.3 – 1.3)	0.7 (0.4 – 1.2)	Not available
Nitrite Nitrogen (NO2-N) (mg/l)		0.023 (0.004 – 0.093)	0.021 (0.003 – 0.088)	Not available	0.045 (0.008 – 0.114)	0.038 (0.010 – 0.078)	Not available
Nitrate Nitrogen (NO3-N) (mg/l)		0.091 (0.028 – 0.213)	0.080 (0.017 – 0.196)	Not available	0.177 (0.047 – 0.343)	0.153 (0.046 – 0.270)	Not available
Ammonia Nitrogen (NH3-N) (mg/l)		0.06 (0.02 – 0.13)	0.05 (0.02 – 0.09)	Not available	0.11 (0.05 – 0.17)	0.11 (0.06 – 0.18)	Not available
Unionised Ammonia (UIA) (mg/l)		0.003 (<0.001 – 0.005)	0.002 (<0.001 – 0.005)	Not more than 0.021 mg/l for annual mean	0.005 (0.002 – 0.008)	0.005 (0.002 – 0.010)	Not more than 0.021 mg/l for annual mean
Total Inorganic Nitrogen (TIN) (mg/l)		0.17 (0.09 – 0.36)	0.15 (0.05 – 0.34)	Not more than 0.4 mg/l for annual mean	0.33 (0.20 – 0.48)	0.31 (0.16 – 0.45)	Not more than 0.4 mg/l for annual mean
Total Nitrogen (TN) (mg/l)		0.30 (0.16 – 0.55)	0.27 (0.14 – 0.49)	Not available	0.49 (0.36 – 0.66)	0.48 (0.34 – 0.66)	Not available
Orthophosphate Phosphorus (PO4) (mg/l)		0.016 (0.010 – 0.021)	0.013 (0.009 – 0.019)	Not available	0.023 (0.012 – 0.033)	0.023 (0.015 – 0.037)	Not available
Total Phosphorus (TP) (mg/l)		0.03 (0.02 – 0.04)	0.03 (0.02 – 0.04)	Not available	0.04 (0.03 – 0.05)	0.04 (0.03 – 0.06)	Not available
Chlorophyll-a (µg/l)		2.7 (0.5 – 9.7)	2.4 (0.4 – 10.2)	Not available	1.8 (1.0 – 2.9)	1.8 (1.0 – 2.9)	Not available
E. coli (cfu/100ml)		110 (4 – 1500)	31 (1 – 220)	Not available	1300 (120 – 11000)	2700 (250 – 6900)	Not available
Faecal Coliforms (cfu/100ml)		260 (8 – 2600)	80 (2 – 610)	Not available	2700 (350 – 42000)	6000 (590 – 22000)	Not available

Note:

1. Except as specified, data presented are depth-averaged values calculated by taking the means of three depths: Surface, mid-depth, bottom.

2. Data presented are annual arithmetic means of depth-averaged results except for E. coli and faecal coliforms that are annual geometric means.

3. Data enclosed in brackets indicate the ranges.

4. Shaded cells indicate non-compliance with the WQOs.

(Source: Adopted from EPD Marine Water Quality Hong Kong in 2008)

In the Victoria Harbour WCZ, the WQO compliance rate in 2007 was maintained at 90% while in 2008 was lowered to 80%.. The decrease of compliance was mainly due to the higher TIN levels in a few western harbour stations in June and July 2008. Several monitoring stations in the Victoria Harbour WCZ are located close to sewage outfalls, including VM4 (North Point Preliminary Treatment Works Outfall), VM5 (Wan Chai East and Wan Chai West Preliminary Treatment Works Outfall) and VM8 (Stonecutters Island Sewage Treatment Works – Harbour Area Treatment Scheme Stage 1 Outfall). The water quality at these stations was inevitably subject to the direct impact of sewage discharge from these outfalls.

All selected monitoring stations in the Eastern Buffer WCZ fully complied with the WQOs in 2007 and 2008.

The water quality in the Western Buffer WCZ was influenced by the Pearl River flow with the WQO compliance rate of 92% in 2007. The E. coli level in the zone was high due to the effect of the effluent from HATS Stage 1.

Depth-averaged SS, Surface SS, DO, Bottom DO, TIN and UIA values derived from the EPD’s routine water quality monitoring data for dry and wet seasons are used in the detailed assessment as described in the Section 3.6.1.

3.3.2 Marine Water Quality in To Kwa Wan and Shau Kei Wan Typhoon Shelter

A summary of marine water quality data for EPD monitoring stations at To Kwa Wan (VT11) and Shau Kei Wan (ET2) Typhoon Shelter extracted from EPD’s publication “Marine Water Quality in Hong Kong 2007” is presented in Table 3.9. Locations of these monitoring stations are shown in Figure 3.2.

Table 3.9: Marine Water Quality at To Kwa Wan and Shau Kei Wan Typhoon Shelters in 2007

Parameter		VT11	ET2	WPCO WQO (in marine waters)
Temperature (°C)		23.3 (18.2 – 26.3)	23.0 (19.5 – 25.5)	Not more than 2°C in daily temperature range
Salinity		31.7 (28.6 – 33.3)	32.7 (31.5 – 33.5)	Not to cause more than 10% change
Dissolved Oxygen (DO) (% Saturation)	Depth average	72 (58 – 91)	63 (49 – 79)	Not available
	Bottom	73 (59 – 92)	62 (36 – 82)	Not available
Dissolved Oxygen (DO) (mg/l)	Depth average	5.2 (4.0 – 7.0)	4.5 (3.3 – 5.9)	Not less than 4mg/l for 90% of the samples
	Bottom	5.2 (4.0 – 7.1)	4.5 (2.5 – 6.2)	Not less than 2mg/l for 90% of the samples
pH		7.9 (7.4 – 8.1)	7.9 (7.7 – 8.0)	6.5 – 8.5 (±0.2 from natural range)
Secchi disc Depth (m)		1.6 (0.9 – 2.0)	2.7 (2.0 – 3.0)	Not available
Turbidity (NTU)		12.3 (4.0 – 19.1)	10.7 (7.1 – 15.4)	Not available
Suspended Solids (SS) (mg/l)		5.2 (2.1 – 15.5)	1.9 (1.5 – 2.5)	Not more than 30% increase
5-day Biochemical Oxygen Demand (BOD5) (mg/l)		1.0 (0.6 – 1.7)	0.6 (0.5 – 0.8)	Not available
Nitrite Nitrogen (NO2-N) (mg/l)		0.028 (0.011 – 0.055)	0.018 (0.005 – 0.027)	Not available
Nitrate Nitrogen (NO3-N) (mg/l)		0.139 (0.046 – 0.260)	0.092 (0.037 – 0.140)	Not available
Ammonia Nitrogen (NH3-N) (mg/l)		0.17 (0.09 – 0.26)	0.13 (0.08 – 0.17)	Not available
Unionised Ammonia (UIA) (mg/l)		0.007 (0.001 – 0.011)	0.004 (0.001 – 0.007)	Not more than 0.021 mg/l for annual mean
Total Inorganic Nitrogen (TIN) (mg/l)		0.34 (0.18 – 0.55)	0.24 (0.16 – 0.31)	Not more than 0.4 mg/l for annual mean
Total Nitrogen (TN) (mg/l)		0.53 (0.36 – 0.75)	0.37 (0.28 – 0.46)	Not available
Orthophosphate Phosphorus (PO4) (mg/l)		0.036 (0.030 – 0.049)	0.031 (0.020 – 0.038)	Not available
Total Phosphorus (TP) (mg/l)		0.06 (0.05 – 0.08)	0.05 (0.03 – 0.05)	Not available
Chlorophyll-a (µg/l)		3.6 (0.9 – 6.3)	1.7 (0.9 – 2.4)	Not available
E. coli (cfu/100ml)		2100 (290 – 5500)	710 (330 – 2000)	Not available
Faecal Coliforms (cfu/100ml)		4500 (620 - 10000)	1900 (970 – 7800)	Not available

Notes:

1. Except as specified, data presented are depth-averaged values calculated by taking the means of three depths: Surface, mid-depth, bottom.

2. Data presented are annual arithmetic means of depth-averaged results except for E. coli and faecal coliforms that are annual geometric means.

3. Data in brackets indicate the ranges.

Due to the embayment form and reduced flushing capacity of the typhoon shelter, marine water within the typhoon shelter is vulnerable to pollution. In 2007, high levels of E.coli were recorded at the To Kwa Wan and Shau Kei Wan Typhoon Shelters indicating faecal contamination.

3.3.3 Sediment Quality

The results of marine sediment quality analysis from the marine site investigation along the alignment of the proposed submarine gas pipelines were presented in Section 4. The results indicated that Category H sediment was found at 16 out of 30 vibrocoring locations due to the high contaminant levels of copper (Cu), nickel (Ni), zinc (Zn), mercury (Hg) and silver (Ag) that exceed the Upper Chemical Exceedance Level (UCEL) under the current sediment classification system (ETWB TCW No. 34/2002, Management of Dredged / Excavated Sediment). East Sha Chau Contaminated Mud Pits are anticipated to be the disposal ground for Type 2 and Type 3 (by containment of the sediments in geosynthetic containers) marine dredged sediment. No adverse impact on water quality beyond the mud pit areas during dumping was anticipated provided all conditions on disposal of sediment as specified the dumping permit are strictly followed. This was supported by the results of the environmental monitoring programme for the management of the pits[5].

A summary of sediment quality data for EPD monitoring stations at Victoria Harbour in the vicinity of the submarine gas pipelines (VS3), To Kwa Wan Typhoon Shelter (VS20) and Aldrich Bay Typhoon Shelter (ES5) extracted from EPD’s publication “Marine Water Quality in Hong Kong 2007” is presented in Table 3.10.

Table 3.10: Bottom Sediment Quality at Selected Stations in 2003 – 2007

Contaminants	VS3	VS20	ES5	Sediment Quality Criteria
				LCEL	UCEL
Heavy Metal (mg/kg dry weight)
Cadmium (Cd)	0.4 (0.2 – 0.6)	1.0 (0.7 – 1.6)	0.7 (0.5 – 0.9)	1.5	4
Chromium (Cr)	46 (18 – 59)	92 (69 – 100)	70 (57 – 89)	80	160
Copper (Cu)	140 (57 – 190)	710 (580 – 830)	330 (230 – 430)	65	110
Mercury (Hg)	0.43 (0.21 – 0.72)	1.26 (0.85 – 2.00)	0.41 (0.27 – 0.69)	0.5	1
Nickel (Ni)	21 (10 – 27)	38 (33 – 45)	30 (26 – 36)	40	40
Lead (Pb)	53 (39 – 65)	110 (87 – 130)	85 (67 – 130)	75	110
Silver (Ag)	4.3 (1.7 – 6.0)	5.3 (3.5 – 6.8)	6.8 (4.2 – 9.0)	1	2
Zinc (Zn)	180 (93 – 250)	270 (220 – 320)	400 (320 – 550)	200	270
Metalloid (mg/kg dry weight)
Arsenic	7.3 (5.2 – 9.0)	7.6 (6.0 – 8.7)	8.1 (6.9 – 10.0)	12	42
Organic-PAHs (µg/kg dry weight)
PAHs (Low Molecular Weight)	110 (90 – 140)	14000 (1800 – 42000)	100 (90 – 120)	550	3160
PAHs (High Molecular Weight)	390 (90 – 670)	120000 (21000 – 290000)	740 (370 – 1200)	1700	9600
Organic-non-PAHs (µg/kg dry weight)
Total PCBs	19 (18 – 22)	110 (70 – 140)	21 (18 – 29)	23	180

Note: Shaded value – Exceed the LCEL – Lower Chemical Exceedance Level

Shaded and bolded value – Exceed the UCEL – Upper Chemical Exceedance

Based on EPD’s monitoring data in 2007, the sediment collected at the three typhoon shelters are highly contaminated with heavy metals. To Kwa Wan Typhoon Shelter is also highly contaminated with trace organics (PCBs and PAHs). For Station VS3 located in the Victoria Harbour Channel, the sediment quality is relatively better but still exceeds the criteria for heavy metals. On the other hand, levels of metalloid (Arsenic) were low at all stations.

3.4 Water Sensitive Receivers

In order to evaluate the potential water quality impacts from the Project, water quality sensitive receivers (WSRs) in the Victoria Harbour and its adjacent waters were considered. Major WSRs identified include:

¡ WSD Flushing Water Intakes;

¡ Cooling Water Intakes;

¡ Corals; and

¡ Fish Culture Zones.

Water quality and ecological sensitive receivers identified within the Victoria Harbour and its adjacent waters are shown in Figure 3.2. These WSRs are included for water quality impact assessment as they are potentially affected by the proposed dredging and backfilling works. Potential adverse impacts on far field coral communities (in terms of suspended solids elevation and sedimentation rate) and fish culture zones (in terms of oxygen depletion and suspended solids elevation) have been addressed.

3.5 Assessment Methodology

To assess the potential water quality impact arising from the dredging, laying of pipe and backfilling works for the construction of the submarine gas pipelines, the sources and natures of effluent to be generated during construction were identified and their impacts were quantified where practicable.

As no maintenance dredging is required for the operation of the submarine gas pipelines, there would be no anticipated water quality impact during the operation of the submarine gas pipelines and therefore assessment for operation phase is not necessary.

3.5.1 Hydrodynamic and Water Quality Models

3.5.1.1 Set-up of Hydrodynamic Model

Computer modelling was employed to assess the potential impact on water quality in Victoria Harbour, Western Buffer and Eastern Buffer WCZs associated with the construction of the proposed submarine gas pipelines for different tidal conditions. The hydrodynamic and water quality models were developed by Delft Hydraulics, namely Delft3D-FLOW and Delft3D-WAQ respectively.

In the present study, the basis for modelling of the harbour waters is the existing, validated Western Harbour Model as shown in Figures 3.3 to 3.5. This model covers the relevant part of the Hong Kong waters, including the Pearl Estuary and the Dangan (Lema) Channel. The resolution of the model is between 100 and 200m in the project area. A locally refined domain in the project area was inserted to obtain the above-said resolution. The grid mesh was further modified to generate higher resolution (about 50 m x 100 m) in the vicinity of the proposed submarine gas pipelines as shown in Figure 3.6a and b. Details of the verification of the fine-grid model have been presented in the Water Quality Modelling Methodology PaperF[6]F of the Project. Model verification plots have been extracted from the Paper and provided in Appendix B1.

3.5.1.2 Coastlines and Bathymetry

The coastline configuration and bathymetry set up for the construction phase of the Project were shown in Figures 3.7 and 3.8, taking account of completed reclamation and the latest progress of the concurrent coastal developments.

3.5.1.3 Simulation Periods

The simulated periods cover a complete spring-neap tidal cycle. The actual simulation period is preceded by a spin-up period. The simulation periods are specified below:

Dry season: 9 February 12:00 – 23 February 12:00

Wet season: 26 July 04:00 – 9 August 04:00

In order to determine if spin-up period is sufficient for the simulation, the model is run for one more spring-neap cycle. It is found that the results of the two successive model runs were similar with each other (Appendix B1). As such, a spin-up period of 15 days is used.

3.5.1.4 Boundary Conditions for Water Quality Models

The initial and boundary conditions are set to zero suspended solids concentrations for the modelling exercise and the sediment release from the proposed dredging for the submarine gas pipeline and marine works from concurrent projects are added to the background manually.

3.5.2 Sediment Plume Modelling

3.5.2.1 General

Water quality impacts will arise from dredging activities of the proposed submarine gas pipelines that will disturb the marine bottom sediment, elevate the SS concentrations of the water column and generate sediment plume along the tidal flows. The impact of sediment plume dispersion during the marine works was simulated by a three-dimensional Delft3D-WAQ Model. The WAQ model simulated suspended solids (SS, in mg/L), optionally subdivided over different fractions representing different sediment sources. The simulated SS represented the project related discharges only. The calculated concentrations were interpreted as excess concentrations on top of the background concentrations.

The Delft3D-WAQ model takes into account the sedimentation process by means of a settling velocity, while erosion of bed sediment, causing resuspension of sediment, is governed by a function of the bed shear stress. The parameters adopted in the present study are summarised in Table 3.11.

Table 3.11: Summary of Parameters for Sediment Plume Model (Delft3D-WAQ)

Sediment Plume Model Parameters
Settling velocity	0.5mm/s
Critical shear stress for deposition	0.2N/m^2
Critical shear stress for erosion	0.3N/m^2
Minimum depth where deposition allowed	0.1m
Resuspension rate	30g/m^2/d

Reference: Mott Connell (2007), Laying of Western Cross Harbour Main and Associated Land Mains from West Kowloon to Sai Ying Pun, Final EIA Report

The impacts in terms of DO depletion, unionised ammonia (UIA) and total inorganic nitrogen (TIN) will not be modelled explicitly, but estimated on the basis of the calculated sediment concentrations. This would lead to an estimated increase relative to the background of the concentrations of different contaminants, dependent on the quality of the released sediments. For TIN, it is assumed that the Kjedahl-N content of the sediment is transformed to TIN in water. For UIA, it is assumed that the entire nitrogen content of the bottom is transformed to ammonium and unionised ammonia. The percentage unionised ammonia is estimated on the basis of temperature, salinity and pH on the basis of the formulations used in Delft3D-WAQ (Delft3D-WAQ Technical Reference Manual, September 2005, WL | Delft Hydraulics). The estimation of the factor is worst case and different for wet and dry season. Analogously, this would lead to an estimated decrease relative to the background of the concentrations of DO, dependent on the quality of the released sediments. For DO it is assumed that the entire SOD content of the sediment is transformed to DO decrease. This can be expressed as follows:

∆TIN(x,y,z,t) = ∆SS(x,y,z,t) x (C_SS,Kj-N)

∆NH3(x,y,z,t) = ∆SS(x,y,z,t)x(C_SS,Kj-N) x f(sal,T,pH)

where

TIN	concentration of total inorganic nitrogen (mgN/L)
SS	concentration of suspended solids (mg/L)
CSS,Kj-N	concentration of Kjedahl-N in suspended matter (gN/gSS)
f(sal,temp,pH)	factor unionised ammonia (gNH3/(gNH4+gNH3)
sal	salinity (ppt)
T	temperature (Celsius)
pH	pH
DO	concentration of dissolved oxygen (mg/L)
CSS,SOD	concentration of SOD in suspended matter (gO/gSS)

This approach relies on worst case assumptions. Any removal of pollutants from the water phase with the sedimentation of SS and any replenishment of DO from the atmosphere is neglected.

The values used in this assessment are based on the highest EPD routine marine sediment quality monitoring data recorded at VS3 in 2006 near the dredging area and are summarised in Table 3.12. C_SS,SOD , which is not available from the EPD dataset, is extracted from the laboratory analysis data of sediment samples during marine SI of the Project. The maximum SOD of 13,000 mg O₂/kg obtained from the sediment samples was adopted in the assessment.

Table 3.12: Sediment Quality near the Dredging Area

Parameters	Dry season	Wet season
CSS,Kj-N	1200E-6	510E-6
f(sal,temp,pH)	0.04	0.05
sal	32	30
T	24	26
pH	7.9	7.9

3.5.2.2 Modelling Scenario

Construction of the proposed submarine gas pipelines from To Kwa Wan to North Point for Former Kai Tak Airport Development is scheduled to commence in January 2012 for completion by June 2014. Major marine works includes trench dredging and backfilling by placement of rockfill. Dredging is scheduled to take place from April 2012 to December 2012 while backfilling by placement of rockfill is scheduled to take place from August 2013 to December 2013.

With reference to the construction programme and likely concurrent projects, representative worst case scenarios has been selected for modelling, including all the potentially concurrent dredging activities envisaged during the proposed dredging works for installation of submarine gas pipelines.

Scenario 1 – Installation of Submarine Gas Pipeline Only

This scenario assumes no marine works is taking place concurrently with the dredging for the Installation of the Submarine Gas Pipelines from To Kwa Wan to North Point for Former Kai Tak Airport Development.

Scenario 2 – Installation of Submarine Gas Pipeline with Concurrent Projects

Referring to the construction programme of this Project and latest construction programme of other projects within the Study Area, it is noted that construction period of other projects listed below might overlap with this Project. This scenario assumes the following marine works would take place concurrently in the Year 2012:

¡ Dredging of the trench for Installation of the Submarine Gas Pipelines from To Kwa Wan to North Point for Former Kai Tak Airport Development

¡ Stage 1 dredging within existing seawall for berth construction for Proposed Cruise Terminal at Kai Tak

¡ Stage 1 dredging for manoeuvre basin for Phase I Berth for Proposed Cruise Terminal at Kai Tak

¡ Dredging for seawall foundation at the former Kai Tak Airport runway for the new public landing steps cum fireboat berth for Proposed Cruise Terminal at Kai Tak

¡ Dredging for Temporary Causeway Bay Reclamation, Wan Chai Reclamation and Hong Kong Convention and Exhibition Centre Reclamation for Wan Chai Development Phase II and Central-Wan Chai Bypass

¡ Dredging for providing mooring space at south-east corner of Causeway Bay Typhoon Shelter deepening the seabed level at Kai Tak Barging Point for Shatin-Central Link

¡ Dredging and sand filling for construction of immersed tube sections of Trunk Road T2

¡ Dredging for providing Sufficient Water Depth for Kwai Tsing Container Basin and its Approach Channel

The sediment source locations near the proposed submarine gas pipelines are shown in Figure 3.9. The sources are assumed to be close to the WSRs as a conservative approach, which has been used in the Dredging Works for Proposed Cruise Terminal at Kai Tak EIA Report, Wan Chai Development Phase II and Central-Wan Chai Bypass EIA Report and Environmental Permit No. EP-356/2009 and advised by Project Proponent of Shatin-Central Link and Providing Sufficient Water Depth for Kwai Tsing Container Basin and its Approach Channel at the time of submission of this report.

Dredging works of the Project will be undertaken by a grab dredger. The assumptions made with regards to modelling grab dredging are as follows:

¡ One grab dredger with a maximum production rate of 4,000 m³ per day, 6 days per week, 16 hours per day equate to a maximum rate of 0.0463 m³ s^-1 during dredging operations except for Dredging Works for Proposed Cruise Terminal at Kai Tak and Trunk Road T2 where the closed grab dredgers will work 12 hours a day, for Wan Chai Development Phase II and Central-Wan Chai Bypass where the closed grab dredgers will work 16 hours a day and for Shatin-Central Link where one closed grab dredger will work 12 hours a day and two closed grab dredgers will work 16 hours a day

¡ For the dredging operation, a dry density of 1,300 kgm^-3 has been assumed for the dredged material in deriving the figures. This figure was adopted in the Central Reclamation Phase III - Studies, Site Investigation, Design and Construction EIA studyF[7]F

¡ Spill loss during sediment dredging by a closed grab dredger was assumed to be continuous, 24 hours a day, 7 days per week.

The production rate for Dredging Works for Proposed Cruise Terminal at Kai Tak, Wan Chai Development Phase II and Central-Wan Chai Bypass and Trunk Road T2 are based on the values adopted under the Dredging Works for Proposed Cruise Terminal at Kai Tak approved EIA report and Wan Chai Development Phase II and Central-Wan Chai Bypass approved EIA report and Environmental Permit No. EP-356/2009. For Shatin-Central Link and Providing Sufficient Water Depth for Kwai Tsing Container Basin and its Approach Channel, the production rates are advised by the Project Proponent at the time of submission of this report.

3.5.2.3 Sediment Loss Rates

With respect to the rate of sediment loss during dredging, the Contaminated Spoil Management StudyF[8]F reviewed relevant literature and concluded that losses from closed-grab dredgers were estimated at 11 to 20 kg m^-3 of mud removed. The sediment loss rate (in g/s) for the dredging of the trench for Installation of the Submarine Gas Pipelines from To Kwa Wan to North Point for Former Kai Tak Airport Development and other concurrent works was calculated by applying the daily production rate (in m³/day) to the maximum sediment loss density of 20kg/m³ except for Dredging Works for Proposed Cruise Terminal at Kai Tak, Wan Chai Development Phase II and Central-Wan Chai Bypass and Trunk Road T2. (Assuming a dry density for marine sediment of 1,300 kg m^-3, the sediment loss during dredging is equivalent to a spill amount of approximately 1.54%).

Sediment loss rates during dredging activities for Dredging Works for Proposed Cruise Terminal at Kai Tak are based on the values adopted under the approved EIA report. Mitigation measures have been proposed under the EIA study to reduce the water quality impact to an acceptable level. The loss rates for Dredging Works for Proposed Cruise Terminal at Kai Tak adopted in this EIA study represented the mitigated scenario.

Sediment loss rates during dredging activities for construction of the Wan Chai Development Phase II and Central-Wan Chai Bypass reclamation are based on the values adopted under the approved EIA report. Mitigation measures have been proposed under the EIA study to reduce the water quality impact to an acceptable level. The loss rates for Wan Chai Development Phase II and Central-Wan Chai Bypass adopted in this EIA study represented the mitigated scenarios.

Sediment loss rates during dredging and sand filling for construction of immersed tube sections of Trunk Road T2 are based on the values provided in the approved EIA report for Dredging Works for Proposed Cruise Terminal at Kai Tak.

The production rates for different construction activities were identified and the calculated sediment loss rates for Scenarios 1 and 2 are shown in Table 3.13 and Table 3.14. The corresponding sources locations are given in Figure 3.9. As deployment of silt curtains around the dredging operations are recommended as mitigation measures under the Dredging Works for Proposed Cruise Terminal at Kai Tak and Wan Chai Development Phase II and Central-Wan Chai Bypass approved EIA reports, the loss rates shown in Table 3.14 for these projects are the reduced loss rates under the mitigation scenarios which have considered the effect of silt curtains. On the other hand, deployment of silt curtains have not been considered in calculating the sediment loss rates from the Installation of Submarine Gas Pipelines and Associated Facilities from To Kwa Wan to North Point for Former Kai Tak Airport Development project and other concurrent projects as shown in Table 3.14. These sediment loss rates represent the worst case under the unmitigated scenario. It is assumed that silt curtains will only be deployed if the water quality impacts are found to be unacceptable.

Table 3.13: Maximum Production Rate for Scenario 1

Source	Construction Activity	Production Rate (m^3 per day)	Loss Rate (kg per s)	Working Hours Per Day	Construction Duration (months)
Installation of Submarine Gas Pipelines from To Kwa Wan to North Point – Trench Dredging
A or B	Dredging (1 closed grab dredger with 8 m^3 capacity)	4000	1.39	16	8

Table 3.14: Maximum Production Rates for Scenario 2

Source	Construction Activity	Production Rate (m^3 per day)	Loss Rate (kg per s)	Working Hours Per Day	Construction Duration (months)
Installation of Submarine Gas Pipelines from To Kwa Wan to North Point – Trench Dredging
A or B	Dredging (1 closed grab dredger with 8 m^3 capacity)	4000	1.39	16	8
Proposed Cruise Terminal at Kai Tak - Stage 1 dredging within existing seawall for berth construction****
C	Dredging (1 closed grab dredger with 8 m^3 capacity)	2000	0.23	12	12
D	Dredging (1 closed grab dredger with 8 m^3 capacity)	2000	0.23	12	12
Proposed Cruise Terminal at Kai Tak -Stage 1 dredging for manoeuvre basin for Phase I Berth****
E	Dredging (1 closed grab dredger with 8 m^3 capacity)	2000	0.93	12	12
F	Dredging (1 closed grab dredger with 8 m^3 capacity)	2000	0.93	12	12
Proposed Cruise Terminal at Kai Tak – Public Landing Steps cum Fireboat Berth****
G	Dredging (1 closed grab dredger with 8 m^3 capacity)	1000	0.12	12	6
Shatin-Central Link
H	Dredging (2 closed grab dredger with 8 m^3 capacity)	3000**	2.08	16	-*
I	Dredging (1 closed grab dredger with 8 m^3 capacity)	500	0.23	12	-*
Wan Chai Development Phase II*****
J	Dredging (1 closed grab dredger with 8 m^3 capacity)	6000	0.52	16	12
K	Dredging (1 closed grab dredger with 8 m^3 capacity)	6000	0.52	16	12
L	Dredging (1 closed grab dredger with 8 m^3 capacity)	1500	0.13	16	12
M	Dredging (1 closed grab dredger with 8 m^3 capacity)	6000	0.52	16	12
Trunk Road T2******
N	Sand filling (1 closed grab dredger of 8m^3 capacity)	1000	0.37	12	12
O	Sand filling (1 closed grab dredger of 8m^3 capacity)	1000	0.37	12	12
P	Dredging (2 closed grab dredger with 8 m^3 capacity)	4000	1.85	12	12
Q	Dredging (2 closed grab dredger with 8 m^3 capacity)	4000	1.85	12	12
Providing Sufficient Water Depth for Kwai Tsing Container Basin and its Approach Channel

R	Dredging (1 closed grab dredger with 8 m^3 capacity)	4000	1.44	24	24***
S	Dredging (1 closed grab dredger with 8 m^3 capacity)	4000	1.44	24	24***
T	Dredging (1 closed grab dredger with 8 m^3 capacity)	4000	1.44	24	24***

*Information not available at the time of submission

**per dredger basis

*** approximated value

**** sediment loss rate based on values presented in Table 5.10 of Wan Chai Development Phase II and Central-Wan Chai Bypass approved EIA report

***** maximum dredging rate based on values presented in Table 2 of Environmental Permit No. EP-356/2009; sediment loss rate based on values presented in Table 5.10 of Dredging Works for Proposed Cruise Terminal at Kai Tak approved EIA report

****** maximum dredging rate and sediment loss rate based on values presented in Table 5.11 of Dredging Works for Proposed Cruise Terminal at Kai Tak approved EIA report

Spilling rates for sediment dredging by a closed grab dredger were assumed to take place uniformly over the water column.

Dredging of contaminated and uncontaminated sediment was assumed be carried out at the same rate.

During dredging, a quantity of fine sediment will be lost to suspension that may be transported away from the works area, forming suspended sediment plumes. The formation and transport of sediment plumes from dredging are modelled in this Assignment.

3.5.2.4 Conservative Assumptions in Assessment Methodology

Quantitative uncertainties in the sediment dispersion modelling should be considered when making an evaluation of the modelling predictions. Worst case conditions were adopted as model input to indicate the maximum extent of the potential environmental impacts. The input data tended to be conservative to provide a margin of tolerance. Some examples of the conservative nature of the input parameters are given below:

The dredging rate adopted for the sediment plume modelling represents the maximum production rate that could be achieved during construction. The actual dredging rate would be less as the shallow dredge option would be adopted and lesser quantity of mud would be dredged.

A conservative assumption of sediment loss from a closed grab dredger (that is, 20 kg m^-3) was adopted to generate the sediment loss rate for modelling. This loss rate would, however, be higher than the real situation.

3.5.2.5 Contaminant Release during Dredging

The loss of sediment to suspension during dredging may have chemical effects on the receiving waters. This is because the sediment would contain organic and chemical pollutants. As part of the marine site investigation works for this Project, laboratory testing of sediment samples were undertaken. A full description of the sediment quality testing and the classification of the sediment according to levels of contaminants are contained in Section 4.

Elutriate tests were performed on the sediment samples to simulate and quantify the degree of mobilization of various contaminants such as metals and trace organic contaminants (including PCBs, PAHs, TBT and chlorinated pesticides) into the water column during dredging. An indication of the likelihood of release of heavy metals from the sediment during dredging is given by the results of the elutriate tests from the marine site investigation works. If the contaminant levels are higher in the elutriates in comparison with the blanks (marine water from the same site), it can be concluded that the contaminants are likely to be released into the marine waters during dredging activities. As there is no existing legislative standard or guideline for individual heavy metal contents in marine waters, the UK Water Quality Standards for Coastal Surface Water, Australian and New Zealand Guidelines for Fresh and Marine Waters, Environmental Economic and BPEO Assessment Principals for Integrated Pollution Control and USEPA Salt Water Criterion were adopted as the assessment criteria.

Should there be exceedance of the assessment criteria, conservative tracers will be introduced into the model for Scenario 1 model runs to estimate the dilution that could be generated by the tidal flows and the size of mixing zone of the contaminants. The release rate of tracers will follow the sediment release rate in Table 3.13 at the source (discharge location) and a concentration of 0 g/m³ will be defined at all the boundaries. Since there is no decay of the tracer, the changes in concentration of the tracer at different grid cells will be due to the advection and dispersion of tidal flows. Comparing the concentration at the grid cell of the source (C0) and the concentration at a selected grid cell located away from the source (C1), the dilution rate will be obtained (C0:C1).

3.5.3 Effluent, Sewage and Surface runoff

To assess the impact of the effluent from hydrostatic tests of the water mains system and sewage, wastewater and surface runoff from construction activities upon the nearby water bodies, the extent of hydrostatic tests and construction works associated with the proposed submarine gas pipelines were reviewed and identified. Practical water pollution control measures or mitigation proposals were subsequently recommended to ensure effluent discharged from the construction site will comply with the WPCO criteria.

3.6 Identification of Environmental Impact

3.6.1 Construction Phase

3.6.1.1 Dredging

General

Dredging of marine sediment would be undertaken along the alignment of the proposed submarine gas pipelines. The in-situ volume of dredged sediment for the Project was estimated to be approximately 267,603 m³ (with a bulking factor of 1.5, bulked volume of dredged sediment was estimated to be approximately 401,404 m³). The estimated volume of contaminated dredged sediment requiring confined marine disposal is approximately 76,936 m³ (with a bulking factor of 1.5, bulked volume of dredged sediment was estimated to be approximately 115,404 m³) and contaminated dredged sediment requiring special treatment or disposal is approximately 3,488m³ (with a bulking factor of 1.5, bulked volume of dredged sediment was estimated to be approximately 5,232 m³).

Key water quality concerns during dredging include (i) dredging works that would disturb the marine bottom sediment, causing an increase in SS concentrations in the water column and forming sediment plume along the tidal flows and (ii) construction runoff and drainage, with effluents potentially contaminated with silt, oil and grease.

Potential impacts on water quality from dredging include:

¡ increased suspension of sediment in the water column during dredging activities, with possible consequence of reducing DO levels and increasing nutrient levels;

¡ release of previously bound organic and inorganic constituents such as heavy metals, PAHs, polychlorinated biphenyls (PCBs) and nutrients into the water column, either via suspension or by disturbance as a result of dredging activities; and

¡ release of the same contaminants due to leakage and spillage as a result of poor handling and overflow from barges during dredging and transport.

Impacts would vary depending on the quantities and level of sediment contamination and the nature and locations of the WSRs. All of the above would result in deterioration of the receiving marine water quality and would have adverse effects on WSRs.

Impact of Suspended Sediment

As a result of dredging activities during the construction phase, fine sediment (less than 63 µm) would be lost to suspension. The suspended sediment would be transported by currents to form sediment plumes, which would gradually resettle. The impact from sediment plumes was to increase the suspended sediment concentrations, and caused non-compliance in WQO and other criteria for particular sensitive receivers.

The extent of elevation of ambient suspended sediment concentrations would determine whether or not the impact is adverse or not. The determination of the acceptability of any elevation is based on the WQOs. The WQO of SS is defined as being an allowable elevation of 30% above the background. As directed in a previous study of the environmental impacts of released SSF[9]F, the ambient value is represented by the 90th percentile of reported concentrations.

The depth-averaged and surface SS levels in 90 percentiles during dry and wet seasons are summarised in Table 3.15. These values are derived from the marine water quality monitoring results of the EPD’s routine monitoring stations. The SS levels recorded from 2007 to 2008 were used in this Assignment. Since seawater intakes are generally located near the water surface, the ambient surface SS level were added to the predicted SS elevations at these sensitive receivers for comparison against the relevant water quality criteria.

Table 3.15: Depth-averaged and Surface SS levels near the Dredging Area

Stations	Dry Season		Wet Season
	Depth-averaged	Surface	Depth-averaged	Surface
VM1, VM2 and VM4
Average SS (mg L^-1)	3.4	2.7	5.2	3.8
90 percentile (ambient level)	5.2	4.6	7.1	5.6
30% increase above the ambient level	1.6	1.4	2.1	1.7
JM3, JM4
Average SS (mg L^-1)	2.9	2.2	4.0	3.3
90 percentile (ambient level)	4.8	3.8	4.9	4.6
30% increase above the ambient level	1.5	1.1	1.5	1.4
EM2
Average SS (mg L^-1)	3.0	2.4	4.2	2.7
90 percentile (ambient level)	4.4	3.5	8.1	4.4
30% increase above the ambient level	1.3	1.1	2.4	1.3
VM8, WM1, WM2
Average SS (mg L^-1)	5.4	4.4	5.9	3.3
90 percentile (ambient level)	8.0	7.2	9.6	5.4
30% increase above the ambient level	2.4	2.2	2.9	1.6
WM4
Average SS (mg L^-1)	6.5	5.4	6.3	3.3
90 percentile (ambient level)	10.6	9.9	8.3	4.3
30% increase above the ambient level	3.2	3.0	2.5	1.3

Values in Bold indicate non-compliance of WSD’s SS criterion.

Dry season – November to March; Wet season – May to September; Levels for each station given in Appendix B8

Impact of Dissolved Oxygen, Total Inorganic Nitrogen and Unionised Ammonia

The extent of depletion of ambient DO concentration and elevation of ambient TIN and UIA would determine or not the impact is adverse or not. The determination of the acceptability of any depletion or elevation is based on the WQOs. The WQO of DO, DO bottom, TIN and UIA are defined as being larger than or equal to 4 mgL^-1, larger than or equal to 2 mgL^-1, less than or equal to 0.4 mgL^-1 and less than or equal to 0.021 mgL^-1 respectively.

An assessment of dissolved oxygen depletion and nutrient release during dredging was made in relation to the results of the sediment plume modelling of dredging activities and the sediment quality data of the Study Area. The predicted maximum elevations in tidal and depth-averaged SS concentrations at the construction site were used to estimate the effects of increased SS concentrations on DO, TIN and UIA. The area in the vicinity of alignment of the proposed submarine gas pipelines was of particular concern. In the water quality model, it was assumed that all SOD was exerted and that all TIN and UIA in the sediment were released to the water. These were conservative assumptions and would likely result in an over-prediction of the potential impacts.

The depth-averaged DO, TIN and UIA and bottom layer DO levels during dry and wet seasons are summarised in Table 3.16. To determine compliance with the water quality criteria, background water quality data were required. The average DO, TIN and UIA values derived from the EPD’s routine marine water quality monitoring data recorded from 2007 to 2008 near the dredging area were used in the assessment.

Table 3.16: DO, TIN and UIA levels near the Dredging Area

Stations	Dry Season		Wet Season
	Depth-averaged	Bottom	Depth-averaged	Bottom
VM1, VM2 and VM4
Dissolved Oxygen (mg L^-1)	5.3	5.3	3.3	2.7
Total Inorganic Nitrogen (mg L^-1)	0.22	-	0.32	-
Unionised Ammonia (mg L^-1)	0.004	-	0.006	-
JM3, JM4
Dissolved Oxygen (mg L^-1)	5.6	5.8	4.4	3.6
Total Inorganic Nitrogen (mg L^-1)	0.17	-	0.18	-
Unionised Ammonia (mg L^-1)	0.003	-	0.004	-
EM2
Dissolved Oxygen (mg L^-1)	5.9	6.1	4.5	3.6
Total Inorganic Nitrogen (mg L^-1)	0.14	-	0.17	-
Unionised Ammonia (mg L^-1)	0.002	-	0.003	-
VM8, WM1, WM2
Dissolved Oxygen (mg L^-1)	5.6	5.7	4.0	2.5
Total Inorganic Nitrogen (mg L^-1)	0.25	-	0.35	-
Unionised Ammonia (mg L^-1)	0.004	-	0.006	-
WM4
Dissolved Oxygen (mg L^-1)	5.5	5.7	3.6	2.7
Total Inorganic Nitrogen (mg L^-1)	0.29	-	0.37	-
Unionised Ammonia (mg L^-1)	0.004	-	0.006	-

Values in Bold indicate non-compliance of relevant criteria

Dry season – November to March; Wet season – May to September; Levels for each station given in Appendix B8; The 10-percentile DO values were adopted.

3.6.1.2 Backfilling for the Laying of the Submarine Pipeline

Granular fill (either decomposed granite or armour rock) will be used as backfilling material after the submarine gas pipelines laying works. The rock fill materials will be obtained from land-base sources. As the granular fill does not contain fines material, there will be no sediment plume generation during the backfilling process and the marine water quality will not be affected. The Contractor will follow the General Specification for Civil Engineering Works and the particle size distribution of fill material specified in Clause 6.07. The specifications for general fill material and granular fill material are reproduced in Table 3.17.

Table 3.17: Specifications for General Fill Material and Granular Fill Material

Type of fill material	Percentage by mass passing
	Size	BS test sieve
	200 mm	75 mm	600 m
General fill material	100	75 – 100	N/A
Granular fill material	N/A	100	0 – 5

3.6.1.3 Disposal of Dredged Sediment

Allocation of marine disposal sites and all necessary permits would be applied from relevant authorities for disposal of dredged sediment. Project Proponent would obtain confirmation from CEDD/Marine Fill Committee (MFC) on the disposal options before commencement of the Project. MFC gazetted marine disposal ground within Hong Kong waters is anticipated to be the disposal ground for Type 1 marine dredged sediment while East Sha Chau Contaminated Mud Pits are anticipated to be the disposal ground for Type 2 and Type 3 (by containment of the sediments in geosynthetic containers) marine dredged sediment. No adverse and cumulative impact on water quality beyond the disposal ground and mud pits during dumping was anticipated provided all conditions on disposal of sediment as specified the dumping permit are strictly followed.

3.6.1.4 Hydrostatic/Commissioning Tests of the Gas Pipeline System

For hydrostatic testing of gas pipelines, the gas pipelines will be filled with potable water (a nearly incompressible liquid) and examined for leaks or permanent changes in shape with a specified test pressure. The test will be carried out at room temperature and dosing of chemicals into the water for testing is not required. Hydrostatic tests will be carried out before and after backfilling of the dredged trench (i.e. two tests would be required). Effluent from the hydrostatic test of gas pipelines which the volume of discharge is estimated to be approximately 2,500m³ (1,250m³ per test) will be subjected to sedimentation to ensure compliance with the discharge requirements stipulated in the TM-DSS. Local and coastal waters might be impacted if the water for testing is allowed to discharge into the inshore waters or marine waters of the Victoria Harbour WCZ without mitigation.

3.6.1.5 Surface Runoff, Sewage and Wastewater from Construction Activities

Surface runoff from construction site may contain considerable loads of SS and contaminants during construction activities. Local and coastal waters may be impacted if the construction site run-off is allowed to discharge into the storm drains or natural drainage without mitigation. Potential water quality impact includes run-off and erosion of exposed bare soil and earth, and stockpiles.

Accumulation of solid and liquid waste such as packaging and construction materials, sewage effluent from the construction workforce, and spillage of oil, diesel or solvents by vessels and vehicles involved with the construction, if uncontrolled, will lead to deterioration in water quality. Increased nutrient level from contaminated discharges and sewage effluent will also lead to secondary water quality impacts including decrease in DO concentrations and localised increase in NH₃-N concentrations which will stimulate algal growth.

Sewage would arise from sanitary facilities provided for the on-site construction work force which will be characterised by high levels of BOD, NH₃-N and E. coli.

3.6.2 Operation Phase

No maintenance dredging is required for the future operation of the proposed submarine gas pipelines. There will be no hydrodynamic impact as the operation of the submarine gas pipelines will not involve reclamation or filling that would affect the flow volume within Victoria Harbour.

There will also be no water quality impact during the operation of the submarine gas pipelines as no effluent will be discharged due to operation of the submarine gas pipelines.

3.7 Prediction and Evaluation of Environmental Impacts

3.7.1 Suspended Solids

Water quality impact on the sensitive receivers during the entire duration of dredging works and along the entire alignment was simulated with the maximum possible instantaneous working rate of 0.0463m³s^-1 for two typical spring neap tidal cycles during dry and wet seasons in Hong Kong. Absolute maximum depth averaged and surface SS concentrations for the complete simulation period at each WSR, taking into account the ambient SS concentration, are presented for all scenarios.

The predicted suspended solids elevations and concentrations for all scenarios in dry and wet seasons at marine ecology sensitive receivers and the cooling and seawater intakes are presented in Table 3.18 to Table 3.25 respectively. The results indicated no exceedance of WSD water quality SS criterion at WSD Seawater Intake, suspended solids criterion for fish culture zone and benthic organisms at marine ecological sensitive receivers was recorded. Mitigation measure is therefore not required.

It is noted that Tables 3.24 and 3.25 showed high SS concentrations (> 40 mg L^-1) at WSR C15 (i.e. Excelsior Hotel and World Trade Centre) for Scenarios 2A and 2B with concurrent projects. However, high SS concentrations were not predicted for Scenarios 1A and 1B (Tables 3.22 and 3.23). This suggested that the subject Project only contribute insignificantly to the high SS concentrations. According to the Wan Chai Development Phase II and Central-Wan Chai Bypass approved EIA report, no water quality criteria was found for the cooling water intake. Nevertheless, silt screen was recommended to reduce the SS impacts on the WSR as mentioned in the Wan Chai Development Phase II and Central-Wan Chai Bypass approved EIA report.

The contours presented in Appendix B2 to B5 showed the extent of tidal averaged maximum surface, bottom and depth-averaged SS elevations over the complete simulation period during dry and wet seasons, respectively. As shown in these figures, the extent of SS impact appeared to be confined near the dredging location at To Kwa Wan and North Point. Temporal variations of surface, mid-depth, bottom and depth-averaged SS elevations at various WSRs in close proximity to the submarine gas pipelines during dry and wet seasons are also shown in Appendix B2 to B5.

The contours presented in Appendix B2 to B5 also showed the predicted net sedimentation per metre square per day during dry and wet seasons, respectively. Both figures indicated that the sedimentation rates were highest at waters along the coast of To Kwa Wan and North Point. The sedimentation rate at Cape Collinson, Green Island and Sandy Bay where coral communities are located, will be much lower than 0.1 kg m^-2 per day. Thus, dredging works near To Kwa Wan and North Point will have negligible impact upon the coral communities at waters near Cape Collinson, Green Island and Sandy Bay.

Table 3.18: Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 1A

Sensitive Receivers	Assessment	Maximum SS Elevation (Dry Season)				Maximum SS Elevation (Wet Season)
	Point	Depth averaged		Surface layer		Depth averaged		Surface layer
		SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)
Corals
Cape Collinson	CR1	0.0	1.3	0.0	1.1	0.0	2.4	0.0	1.3
Green Island	CR2	0.0	2.4	0.0	2.2	0.0	2.9	0.0	1.6
Sandy Bay	CR3	0.0	2.4	0.0	2.2	0.0	2.9	0.0	1.6
Corals at Junk Bay	CR4	0.0	1.5	0.0	1.1	0.0	1.5	0.0	1.4
Corals at Junk Bay	CR5	0.0	1.5	0.0	1.1	0.0	1.5	0.0	1.4
Corals at Junk Bay	CR6	0.0	1.5	0.0	1.1	0.1	1.5	0.1	1.4
Corals at Junk Bay – Junk Island	CR7	0.1	1.5	0.0	1.1	0.0	1.5	0.0	1.4
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.0	1.3	0.0	1.1	0.0	2.4	0.0	1.3
Ma Wan Fish Culture Zone	F2	0.0	3.2	0.0	3.0	0.0	2.5	0.0	1.3

SS Criteria for Corals are 30% of the ambient level

Values in Bold indicates exceedance of relevant criteria

Table 3.19: Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 1B

Sensitive Receivers	Assessment	Maximum SS Elevation (Dry Season)				Maximum SS Elevation (Wet Season)
	Point	Depth averaged		Surface layer		Depth averaged		Surface layer
		SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)
Corals
Cape Collinson	CR1	0.0	1.3	0.0	1.1	0.0	2.4	0.0	1.3
Green Island	CR2	0.0	2.4	0.0	2.2	0.0	2.9	0.0	1.6
Sandy Bay	CR3	0.0	2.4	0.0	2.2	0.0	2.9	0.0	1.6
Corals at Junk Bay	CR4	0.0	1.5	0.0	1.1	0.0	1.5	0.0	1.4
Corals at Junk Bay	CR5	0.0	1.5	0.0	1.1	0.0	1.5	0.0	1.4
Corals at Junk Bay	CR6	0.0	1.5	0.0	1.1	0.2	1.5	0.0	1.4
Corals at Junk Bay – Junk Island	CR7	0.1	1.5	0.1	1.1	0.1	1.5	0.0	1.4
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.0	1.3	0.0	1.1	0.0	2.4	0.0	1.3
Ma Wan Fish Culture Zone	F2	0.0	3.2	0.0	3.0	0.0	2.5	0.0	1.3

SS Criteria for Corals are 30% of the ambient level

Values in Bold indicates exceedance of relevant criteria

Table 3.20: Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 2A

Sensitive Receivers	Assessment	Maximum SS Elevation (Dry Season)				Maximum SS Elevation (Wet Season)
	Point	Depth averaged		Surface layer		Depth averaged		Surface layer
		SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)
Corals
Cape Collinson	CR1	0.0	1.3	0.0	1.1	0.1	2.4	0.1	1.3
Green Island	CR2	0.6	2.4	0.5	2.2	0.3	2.9	0.1	1.6
Sandy Bay	CR3	0.5	2.4	0.3	2.2	0.2	2.9	0.2	1.6
Corals at Junk Bay	CR4	0.0	1.5	0.0	1.1	0.1	1.5	0.0	1.4
Corals at Junk Bay	CR5	0.1	1.5	0.1	1.1	0.2	1.5	0.1	1.4
Corals at Junk Bay	CR6	0.3	1.5	0.2	1.1	0.7	1.5	0.7	1.4
Corals at Junk Bay – Junk Island	CR7	0.3	1.5	0.2	1.1	0.5	1.5	0.5	1.4
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.0	1.3	0.0	1.1	0.2	2.4	0.1	1.3
Ma Wan Fish Culture Zone	F2	0.6	3.2	0.5	3.0	0.6	2.5	0.1	1.3

SS Criteria for Corals are 30% of the ambient level

Values in Bold indicates exceedance of relevant criteria

Table 3.21: Predicted Suspended Solids Elevations at Marine Ecology and Fisheries Sensitive Receivers for Scenario 2B

Sensitive Receivers	Assessment	Maximum SS Elevation (Dry Season)				Maximum SS Elevation (Wet Season)
	Point	Depth averaged		Surface layer		Depth averaged		Surface layer
		SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)	SS Elevation (mgL^-1)	SS Criteria (mgL^-1)
Corals
Cape Collinson	CR1	0.1	1.3	0.0	1.1	0.1	2.4	0.1	1.3
Green Island	CR2	0.6	2.4	0.5	2.2	0.3	2.9	0.1	1.6
Sandy Bay	CR3	0.6	2.4	0.3	2.2	0.2	2.9	0.2	1.6
Corals at Junk Bay	CR4	0.1	1.5	0.0	1.1	0.1	1.5	0.0	1.4
Corals at Junk Bay	CR5	0.1	1.5	0.1	1.1	0.2	1.5	0.1	1.4
Corals at Junk Bay	CR6	0.3	1.5	0.2	1.1	0.9	1.5	0.6	1.4
Corals at Junk Bay – Junk Island	CR7	0.3	1.5	0.2	1.1	0.5	1.5	0.4	1.4
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.0	1.3	0.0	1.1	0.2	2.4	0.1	1.3
Ma Wan Fish Culture Zone	F2	0.6	3.2	0.5	3.0	0.6	2.5	0.1	1.3

SS Criteria for Corals are 30% of the ambient level

Values in Bold indicates exceedance of relevant criteria

Table 3.22: Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 1A

Sensitive Receivers	Maximum^(1) SS concentration in surface layer (mgL^-1)
	Assessment Point	SS Criterion (mgL^-1)	Dry Season	Wet Season
Cooling Water Intakes
MTRC Tsing Yi Station	C1	-	7.2	5.4
MTRC Kowloon Station	C2	-	4.9	5.7
China H.K. City	C3	-	4.7	5.6
Harbour City	C4	-	4.6	5.6
Ocean Centre	C5	-	4.6	5.6
Ocean Terminal	C6	-	4.7	5.6
Government Premises	C7	-	5.2	5.7
New World Centre	C8	-	5.1	5.7
East Rail Extension	C9	-	4.8	5.7
Yau Tong Bay Ice Plant	C10	-	4.9	5.7
Pamela Youde Nethersole Eastern Hospital	C11	-	4.6	5.7
Provident Centre	C12	-	4.6	5.7
City Garden	C13	-	4.6	5.7
Windsor House	C14	-	4.6	5.6
Excelsior Hotel and World Trade Centre	C15	-	4.6	5.6
Sun Hung Kai Centre	C16	-	4.6	5.7
Great Eagle Centre / China Resources Building	C17	-	4.7	5.7
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	-	4.7	5.7
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	-	4.7	5.7
Hong Kong Convention and Exhibition Centre Phase I	C20	-	4.7	5.7
Hong Kong Convention and Exhibition Centre Extension	C21	-	4.7	5.7
Queensway Government Offices	C22	-	4.6	5.7
Hong Kong and Shanghai Bank (HSBC) Pumping Station Intake	C23	-	4.6	5.7
Prince’s Building Group, Mandarin Hotel Intakes	C24	-	4.7	5.7
MTRC South Intake	C25	40	4.7	5.8
Sha Wan Drive	C26	-	4.6	5.6
Queen Mary Hospital	C27	-	4.6	5.6
North Point Government Offices	C28	-	4.6	5.7
Taikoo Place	C29	-	4.6	5.7
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	<10	7.2	5.4
Cheung Sha Wan Salt Water Pumping Station	WSD2	<10	7.2	5.4
Kowloon South Salt Water Pumping Station	WSD3	<10	7.3	5.4
Yau Ma Tei Salt Water Pumping Station	WSD4	<10	7.2	5.4
Tai Wan Salt Water Pumping Station	WSD5	<10	7.0	6.7
Cha Kwo Ling Salt Water Pumping Station	WSD6	<10	4.9	5.7
Yau Tong Salt Water Pumping Station	WSD7	<10	4.9	5.7
Siu Sai Wan Salt Water Pumping Station	WSD8	<10	3.5	4.4
Heng Fa Chuen Salt Water Pumping Station	WSD9	<10	3.5	4.4
Sai Wan Ho Salt Water Pumping Station	WSD10	<10	4.7	5.7
Quarry Bay Salt Water Pumping Station	WSD11	<10	4.7	5.7
Wan Chai Salt Water Pumping Station	WSD12	<10	4.6	5.7
Sheung Wan Salt Water Pumping Station	WSD13	<10	7.3	5.4
Kennedy Town Salt Water Pumping Station	WSD14	<10	7.2	5.4
North Point	WSD15	<10	4.6	5.7
Central Waterfront	WSD16	<10	4.7	5.8

- Value in Bold indicates exceedance of relevant criteria.

(1) Absolute value of SS includes the ambient SS level presented in Table 3.15 plus the SS elevations predicted.

Table 3.23: Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 1B

Sensitive Receivers	Maximum^(1) SS concentration in surface layer (mgL^-1)
	Assessment Point	SS Criterion (mgL^-1)	Dry Season	Wet Season
Cooling Water Intakes
MTRC Tsing Yi Station	C1	-	7.2	5.3
MTRC Kowloon Station	C2	-	4.7	5.7
China H.K. City	C3	-	4.6	5.8
Harbour City	C4	-	4.6	5.6
Ocean Centre	C5	-	4.6	5.6
Ocean Terminal	C6	-	4.6	5.6
Government Premises	C7	-	4.7	5.6
New World Centre	C8	-	4.7	5.6
East Rail Extension	C9	-	4.6	5.6
Yau Tong Bay Ice Plant	C10	-	4.7	5.6
Pamela Youde Nethersole Eastern Hospital	C11	-	4.6	5.6
Provident Centre	C12	-	6.3	5.6
City Garden	C13	-	6.3	5.6
Windsor House	C14	-	4.7	5.6
Excelsior Hotel and World Trade Centre	C15	-	4.6	5.6
Sun Hung Kai Centre	C16	-	5.0	5.6
Great Eagle Centre / China Resources Building	C17	-	5.3	5.5
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	-	5.3	5.5
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	-	5.3	5.5
Hong Kong Convention and Exhibition Centre Phase I	C20	-	5.3	5.8
Hong Kong Convention and Exhibition Centre Extension	C21	-	5.3	5.8
Queensway Government Offices	C22	-	4.9	5.8
Hong Kong and Shanghai Bank (HSBC) Pumping Station Intake	C23	-	5.0	5.9
Prince’s Building Group, Mandarin Hotel Intakes	C24	-	5.1	5.6
MTRC South Intake	C25	40	5.0	5.6
Sha Wan Drive	C26	-	4.6	5.7
Queen Mary Hospital	C27	-	4.6	5.6
North Point Government Offices	C28	-	7.7	5.7
Taikoo Place	C29	-	7.1	5.7
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	<10	7.2	5.4
Cheung Sha Wan Salt Water Pumping Station	WSD2	<10	7.2	5.4
Kowloon South Salt Water Pumping Station	WSD3	<10	7.2	5.4
Yau Ma Tei Salt Water Pumping Station	WSD4	<10	7.2	5.4
Tai Wan Salt Water Pumping Station	WSD5	<10	4.7	5.6
Cha Kwo Ling Salt Water Pumping Station	WSD6	<10	4.7	5.6
Yau Tong Salt Water Pumping Station	WSD7	<10	4.8	5.6
Siu Sai Wan Salt Water Pumping Station	WSD8	<10	3.6	4.4
Heng Fa Chuen Salt Water Pumping Station	WSD9	<10	3.6	4.5
Sai Wan Ho Salt Water Pumping Station	WSD10	<10	5.3	6.1
Quarry Bay Salt Water Pumping Station	WSD11	<10	7.5	6.5
Wan Chai Salt Water Pumping Station	WSD12	<10	4.9	5.7
Sheung Wan Salt Water Pumping Station	WSD13	<10	7.3	5.3
Kennedy Town Salt Water Pumping Station	WSD14	<10	7.2	5.4
North Point	WSD15	<10	6.3	5.6
Central Waterfront	WSD16	<10	5.0	5.6

- Value in Bold indicates exceedance of relevant criteria.

(1) Absolute value of SS includes the ambient SS level presented in Table 3.15 plus the SS elevations predicted.

Table 3.24: Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 2A

Sensitive Receivers	Maximum ^(1)SS concentration in surface layer (mgL^-1)
	Assessment Point	SS Criterion (mgL^-1)	Dry Season	Wet Season
Cooling Water Intakes
MTRC Tsing Yi Station	C1	-	7.4	5.6
MTRC Kowloon Station	C2	-	5.2	5.7
China H.K. City	C3	-	4.7	5.6
Harbour City	C4	-	4.7	5.6
Ocean Centre	C5	-	4.7	5.6
Ocean Terminal	C6	-	4.8	5.6
Government Premises	C7	-	6.0	5.8
New World Centre	C8	-	5.5	5.8
East Rail Extension	C9	-	4.8	5.7
Yau Tong Bay Ice Plant	C10	-	7.0	6.9
Pamela Youde Nethersole Eastern Hospital	C11	-	4.7	5.9
Provident Centre	C12	-	5.8	6.2
City Garden	C13	-	5.7	6.3
Windsor House	C14	-	7.9	9.5
Excelsior Hotel and World Trade Centre	C15	-	49.8	39.3
Sun Hung Kai Centre	C16	-	14.4	13.5
Great Eagle Centre / China Resources Building	C17	-	5.8	6.8
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	-	5.8	6.8
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	-	5.8	6.8
Hong Kong Convention and Exhibition Centre Phase I	C20	-	5.8	6.8
Hong Kong Convention and Exhibition Centre Extension	C21	-	5.8	6.8
Queensway Government Offices	C22	-	6.0	7.4
Hong Kong and Shanghai Bank (HSBC) Pumping Station Intake	C23	-	5.8	6.7
Prince’s Building Group, Mandarin Hotel Intakes	C24	-	5.4	6.4
MTRC South Intake	C25	40	5.3	6.2
Sha Wan Drive	C26	-	4.9	5.7
Queen Mary Hospital	C27	-	4.8	5.7
North Point Government Offices	C28	-	5.1	5.9
Taikoo Place	C29	-	5.1	5.9
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	<10	7.5	5.7
Cheung Sha Wan Salt Water Pumping Station	WSD2	<10	7.2	5.4
Kowloon South Salt Water Pumping Station	WSD3	<10	7.4	5.4
Yau Ma Tei Salt Water Pumping Station	WSD4	<10	7.2	5.4
Tai Wan Salt Water Pumping Station	WSD5	<10	7.5	6.9
Cha Kwo Ling Salt Water Pumping Station	WSD6	<10	8.2	7.3
Yau Tong Salt Water Pumping Station	WSD7	<10	5.5	6.4
Siu Sai Wan Salt Water Pumping Station	WSD8	<10	3.6	4.5
Heng Fa Chuen Salt Water Pumping Station	WSD9	<10	3.6	4.7
Sai Wan Ho Salt Water Pumping Station	WSD10	<10	5.2	6.0
Quarry Bay Salt Water Pumping Station	WSD11	<10	5.3	5.9
Wan Chai Salt Water Pumping Station	WSD12	<10	8.6	8.2
Sheung Wan Salt Water Pumping Station	WSD13	<10	7.5	5.4
Kennedy Town Salt Water Pumping Station	WSD14	<10	7.3	5.4
North Point	WSD15	<10	5.8	6.2
Central Waterfront	WSD16	<10	5.3	6.2

- Value in Bold indicates exceedance of relevant criteria.

(1) Absolute value of SS includes the ambient SS level presented in Table 3.15 plus the SS elevations predicted.

Table 3.25: Predicted Suspended Solids Concentrations at Cooling and Sea Water Intakes for Scenario 2B

Sensitive Receivers	Maximum ^(1)SS concentration in surface layer (mgL^-1)
	Assessment Point	SS Criterion (mgL^-1)	Dry Season	Wet Season
Cooling Water Intakes
MTRC Tsing Yi Station	C1	-	7.4	5.6
MTRC Kowloon Station	C2	-	4.9	5.7
China H.K. City	C3	-	4.7	5.8
Harbour City	C4	-	4.6	5.6
Ocean Centre	C5	-	4.6	5.6
Ocean Terminal	C6	-	4.7	5.6
Government Premises	C7	-	5.4	5.7
New World Centre	C8	-	5.0	5.7
East Rail Extension	C9	-	4.7	5.7
Yau Tong Bay Ice Plant	C10	-	6.8	6.9
Pamela Youde Nethersole Eastern Hospital	C11	-	4.8	5.8
Provident Centre	C12	-	7.4	6.2
City Garden	C13	-	7.4	6.2
Windsor House	C14	-	7.9	9.5
Excelsior Hotel and World Trade Centre	C15	-	49.8	39.2
Sun Hung Kai Centre	C16	-	14.8	13.4
Great Eagle Centre / China Resources Building	C17	-	6.4	6.6
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	-	6.4	6.6
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	-	6.4	6.5
Hong Kong Convention and Exhibition Centre Phase I	C20	-	6.4	6.9
Hong Kong Convention and Exhibition Centre Extension	C21	-	6.4	6.9
Queensway Government Offices	C22	-	6.3	7.5
Hong Kong and Shanghai Bank (HSBC) Pumping Station Intake	C23	-	6.1	6.9
Prince’s Building Group, Mandarin Hotel Intakes	C24	-	5.8	6.3
MTRC South Intake	C25	40	5.6	6.0
Sha Wan Drive	C26	-	4.9	5.7
Queen Mary Hospital	C27	-	4.8	5.7
North Point Government Offices	C28	-	8.1	5.9
Taikoo Place	C29	-	7.5	5.9
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	<10	7.5	5.7
Cheung Sha Wan Salt Water Pumping Station	WSD2	<10	7.2	5.4
Kowloon South Salt Water Pumping Station	WSD3	<10	7.3	5.4
Yau Ma Tei Salt Water Pumping Station	WSD4	<10	7.2	5.4
Tai Wan Salt Water Pumping Station	WSD5	<10	5.2	5.8
Cha Kwo Ling Salt Water Pumping Station	WSD6	<10	8.0	7.3
Yau Tong Salt Water Pumping Station	WSD7	<10	5.4	6.3
Siu Sai Wan Salt Water Pumping Station	WSD8	<10	3.7	4.5
Heng Fa Chuen Salt Water Pumping Station	WSD9	<10	3.7	4.8
Sai Wan Ho Salt Water Pumping Station	WSD10	<10	5.8	6.4
Quarry Bay Salt Water Pumping Station	WSD11	<10	8.1	6.7
Wan Chai Salt Water Pumping Station	WSD12	<10	8.9	8.2
Sheung Wan Salt Water Pumping Station	WSD13	<10	7.6	5.4
Kennedy Town Salt Water Pumping Station	WSD14	<10	7.3	5.4
North Point	WSD15	<10	7.4	6.2
Central Waterfront	WSD16	<10	5.6	6.0

- Value in Bold indicates exceedance of relevant criteria.

(1) Absolute value of SS includes the ambient SS level presented in Table 3.15 plus the SS elevations predicted.

3.7.2 Dissolved Oxygen, Total Inorganic Nitrogen and Unionised Ammonia

An assessment of dissolved oxygen (DO) depletion, total inorganic nitrogen and unionised ammonia elevations during dredging has been made in relation to the results of the sediment plume modelling of dredging activities and the sediment quality data for the study area. The predicted maximum elevations at various indicator points were used to estimate the effects of increased SS concentrations on DO, TIN and UIA. In the calculation, it was assumed that all the sediment oxygen demand is exerted. These are conservative assumptions and will likely result in an over-prediction of the potential impacts. The calculation was performed using the highest level of sediment oxygen demand measured in the sediment samples collected during the marine SI for conservative predictions. The highest SOD level was 13,000 mgO₂/kg recorded at station VC1A.

Referring to Table 3.16 which shows the background depth-averaged and bottom DO, depth-averaged TIN and UIA concentration recorded during dry and wet season for various EPD routine monitoring stations, the depth-average DO at stations VM1, 2 and 4,EM2 and WM4 at wet season did not comply with the WQO for DO (Not less than 4 mg/L for 90% of the sampling occasions during the whole year for marine waters except fish culture subzones and Not less than 5 mg/L for 90% of the sampling occasions during the whole year for fish culture subzones).

The predicted maximum depth-averaged and bottom layer dissolved oxygen, total inorganic nitrogen and unionised ammonia elevations and concentrations for all scenarios in dry and wet seasons at marine ecology sensitive receivers and the cooling and seawater intakes are presented in Table 3.26 to Table 3.33. The results indicated that no exceedance of WQO of TIN and UIA was recorded. For bottom level DO, non-compliance is predicted at WSR C15 at wet season only. The results of DO at wet season had non-compliance of the WQO criteria at some of the sensitive receivers. As discussed previously, however, the non-compliance of the criteria is mainly due to the non-compliance of the ambient depth-averaged DO levels at Victoria Harbour (i.e. VM1, 2 and 4) and near Tung Lung Chau (i.e. EM2) and Ma Wan fish culture zones (i.e. WM4) under assessment for marine water and fish culture zones, respectively.

The contours presented in Appendix B2 to B5 showed the extent of tidal and depth-averaged DO depletion, DO depletion at bottom layer and TIN and UIA elevations over a spring-neap cycle during dry and wet seasons, respectively. As shown in these figures, the extent of DO, TIN and UIA impact appeared to be confined near the dredging location at To Kwa Wan and North Point. Temporal variations of DO depletion, TIN and UIA elevations at various WSRs during dry and wet seasons are also shown in Appendix B2 to B5.

As presented in Table 3.26 to Table 3.33, it was shown that the depletion of DO, the elevation of TIN and UIA due to the subject project are minimal. Without the concurrent project (i.e. Scenario 1A and 1B), the maximum depletion of depth-averaged and bottom-level DO, the elevation of TIN and UIA are 0.1, 0.1, 0.01 and 0.000 respectively at WSR C28. With the concurrent projects (i.e. Scenario 2A and 2B), the maximum depletion of depth-averaged DO, bottom-level DO the elevation of TIN and UIA is 0.9, 1.6, 0.08 and 0.003 at WSR C15. Although the bottom-level DO depletion leaded to a non-compliance of DO at WSR C15 at wet season, it is mainly due to the contributions of concurrent projects by comparing the results of Scenarios 1A/1B and Scenarios 2A/2B. As such, the impacts of decrease in DO and increase in TIN and UIA due to the subject project is considered trivial. Implication of algal bloom and red tide is therefore minimal and mitigation measure is therefore not required.

DO, TIN and UIA impact due to this project and the concurrent projects have been assessed. Table 3.30 to Table 3.33 show that there are potential exceedances of DO and TIN criteria in WQO at some of the sensitive receivers; however, many of these are due to the very high background levels which have already exceeded the WQO criteria. In view of the small contribution from this project as shown in Table 3.26 to Table 3.29, the exceedance due to cumulative water quality impact from concurrent projects is considered not due to this project.

Table 3.26: Predicted Dissolved Oxygen Concentrations for Scenario 1A

Sensitive Receivers	Assess-ment Point	Minimum Depth-averaged DO level (mgL^-1)						Minimum DO level at bottom layer (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO
Corals
Cape Collinson	CR1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Green Island	CR2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Sandy Bay	CR3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Corals at Junk Bay	CR4	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR5	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR6	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay – Junk Island	CR7	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Ma Wan Fish Culture Zone	F2	5.5	0.0	5.5	3.6	0.0	3.6	5.7	0.0	5.7	2.7	0.0	2.7
Cooling Water Intakes
MTRC Tsing Yi Station	C1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
MTRC Kowloon Station	C2	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
China H.K. City	C3	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Harbour City	C4	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Centre	C5	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Terminal	C6	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Government Premises	C7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
New World Centre	C8	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
East Rail Extension	C9	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Yau Tong Bay Ice Plant	C10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Pamela Youde Nethersole	C11	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Provident Centre	C12	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
City Garden	C13	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Windsor House	C14	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Excelsior Hotel and World Trade Centre	C15	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Sun Hung Kai Centre	C16	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Great Eagle Centre / China Resources Building	C17	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Hong Kong Convention and	C20	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Hong Kong Convention and	C21	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Queensway Government Offices	C22	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Hong Kong and Shanghai Bank	C23	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Prince’s Building Group,	C24	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
MTRC South Intake	C25	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Sha Wan Drive	C26	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Queen Mary Hospital	C27	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
North Point Government Offices	C28	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Taikoo Place	C29	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Cheung Sha Wan Salt Water Pumping Station	WSD2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kowloon South Salt Water Pumping Station	WSD3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Yau Ma Tei Salt Water Pumping Station	WSD4	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Tai Wan Salt Water Pumping Station	WSD5	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Cha Kwo Ling Salt Water Pumping Station	WSD6	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Yau Tong Salt Water Pumping Station	WSD7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Siu Sai Wan Salt Water Pumping Station	WSD8	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Heng Fa Chuen Salt Water Pumping Station	WSD9	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Sai Wan Ho Salt Water Pumping Station	WSD10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Quarry Bay Salt Water Pumping Station	WSD11	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Wan Chai Salt Water Pumping Station	WSD12	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Sheung Wan Salt Water Pumping Station	WSD13	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kennedy Town Salt Water Pumping Station	WSD14	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
North Point	WSD15	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Central Waterfront	WSD16	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7

- Value in Bold indicates exceedance of relevant criteria.

Table 3.27: Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 1A

Sensitive Receivers	Assess-ment Point	Maximum TIN Concentration (mgL^-1)						Maximum UIA Concentration (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	TIN elevat-ion	Max. TIN	Back-ground	TIN elevat-ion	Max. TIN	Back-ground	UIA elevat-ion	Max. UIA	Back-ground	UIA elevat-ion	Max. UIA
Corals
Cape Collinson	CR1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Green Island	CR2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Sandy Bay	CR3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Corals at Junk Bay	CR4	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR5	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR6	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay – Junk Island	CR7	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Ma Wan Fish Culture Zone	F2	0.29	0.00	0.29	0.37	0.00	0.37	0.004	0.000	0.004	0.006	0.000	0.006
Cooling Water Intakes
MTRC Tsing Yi Station	C1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
MTRC Kowloon Station	C2	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
China H.K. City	C3	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Harbour City	C4	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Centre	C5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Terminal	C6	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Government Premises	C7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
New World Centre	C8	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
East Rail Extension	C9	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Bay Ice Plant	C10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Pamela Youde Nethersole	C11	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Provident Centre	C12	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
City Garden	C13	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Windsor House	C14	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Excelsior Hotel and World Trade Centre	C15	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sun Hung Kai Centre	C16	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Great Eagle Centre / China Resources Building	C17	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C20	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C21	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queensway Government Offices	C22	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong and Shanghai Bank	C23	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Prince’s Building Group,	C24	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
MTRC South Intake	C25	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sha Wan Drive	C26	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queen Mary Hospital	C27	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
North Point Government Offices	C28	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Taikoo Place	C29	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Cheung Sha Wan Salt Water Pumping Station	WSD2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kowloon South Salt Water Pumping Station	WSD3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Yau Ma Tei Salt Water Pumping Station	WSD4	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Tai Wan Salt Water Pumping Station	WSD5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Cha Kwo Ling Salt Water Pumping Station	WSD6	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Salt Water Pumping Station	WSD7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Siu Sai Wan Salt Water Pumping Station	WSD8	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Heng Fa Chuen Salt Water Pumping Station	WSD9	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Sai Wan Ho Salt Water Pumping Station	WSD10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Quarry Bay Salt Water Pumping Station	WSD11	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Salt Water Pumping Station	WSD12	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sheung Wan Salt Water Pumping Station	WSD13	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kennedy Town Salt Water Pumping Station	WSD14	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
North Point	WSD15	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Central Waterfront	WSD16	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006

- Value in Bold indicates exceedance of relevant criteria.

Table 3.28: Predicted Dissolved Oxygen Concentrations for Scenario 1B

Sensitive Receivers	Assess-ment Point	Minimum Depth-averaged DO level (mgL^-1)						Minimum DO level at bottom layer (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO
Corals
Cape Collinson	CR1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Green Island	CR2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Sandy Bay	CR3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Corals at Junk Bay	CR4	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR5	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR6	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay – Junk Island	CR7	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Ma Wan Fish Culture Zone	F2	5.5	0.0	5.5	3.6	0.0	3.6	5.7	0.0	5.7	2.7	0.0	2.7
Cooling Water Intakes
MTRC Tsing Yi Station	C1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
MTRC Kowloon Station	C2	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
China H.K. City	C3	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Harbour City	C4	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Centre	C5	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Terminal	C6	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Government Premises	C7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
New World Centre	C8	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
East Rail Extension	C9	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Yau Tong Bay Ice Plant	C10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Pamela Youde Nethersole	C11	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Provident Centre	C12	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
City Garden	C13	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Windsor House	C14	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Excelsior Hotel and World Trade Centre	C15	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Sun Hung Kai Centre	C16	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Great Eagle Centre / China Resources Building	C17	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Hong Kong Convention and	C20	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Hong Kong Convention and	C21	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Queensway Government Offices	C22	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Hong Kong and Shanghai Bank	C23	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Prince’s Building Group,	C24	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
MTRC South Intake	C25	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Sha Wan Drive	C26	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Queen Mary Hospital	C27	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
North Point Government Offices	C28	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Taikoo Place	C29	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Cheung Sha Wan Salt Water Pumping Station	WSD2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kowloon South Salt Water Pumping Station	WSD3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Yau Ma Tei Salt Water Pumping Station	WSD4	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Tai Wan Salt Water Pumping Station	WSD5	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Cha Kwo Ling Salt Water Pumping Station	WSD6	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Yau Tong Salt Water Pumping Station	WSD7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Siu Sai Wan Salt Water Pumping Station	WSD8	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Heng Fa Chuen Salt Water Pumping Station	WSD9	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Sai Wan Ho Salt Water Pumping Station	WSD10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Quarry Bay Salt Water Pumping Station	WSD11	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Wan Chai Salt Water Pumping Station	WSD12	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Sheung Wan Salt Water Pumping Station	WSD13	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kennedy Town Salt Water Pumping Station	WSD14	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
North Point	WSD15	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Central Waterfront	WSD16	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7

- Value in Bold indicates exceedance of relevant criteria.

Table 3.29: Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 1B

Sensitive Receivers	Assess-ment Point	Maximum TIN Concentration (mgL^-1)						Maximum UIA Concentration (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	TIN elevat-ion	Max. TIN	Back-ground	TIN elevat-ion	Max. TIN	Back-ground	UIA elevat-ion	Max. UIA	Back-ground	UIA elevat-ion	Max. UIA
Corals
Cape Collinson	CR1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Green Island	CR2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Sandy Bay	CR3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Corals at Junk Bay	CR4	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR5	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR6	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay – Junk Island	CR7	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Ma Wan Fish Culture Zone	F2	0.29	0.00	0.29	0.37	0.00	0.37	0.004	0.000	0.004	0.006	0.000	0.006
Cooling Water Intakes
MTRC Tsing Yi Station	C1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
MTRC Kowloon Station	C2	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
China H.K. City	C3	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Harbour City	C4	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Centre	C5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Terminal	C6	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Government Premises	C7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
New World Centre	C8	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
East Rail Extension	C9	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Bay Ice Plant	C10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Pamela Youde Nethersole	C11	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Provident Centre	C12	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
City Garden	C13	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Windsor House	C14	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Excelsior Hotel and World Trade Centre	C15	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sun Hung Kai Centre	C16	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Great Eagle Centre / China Resources Building	C17	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C20	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C21	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queensway Government Offices	C22	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong and Shanghai Bank	C23	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Prince’s Building Group,	C24	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
MTRC South Intake	C25	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sha Wan Drive	C26	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queen Mary Hospital	C27	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
North Point Government Offices	C28	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Taikoo Place	C29	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Cheung Sha Wan Salt Water Pumping Station	WSD2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kowloon South Salt Water Pumping Station	WSD3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Yau Ma Tei Salt Water Pumping Station	WSD4	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Tai Wan Salt Water Pumping Station	WSD5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Cha Kwo Ling Salt Water Pumping Station	WSD6	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Salt Water Pumping Station	WSD7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Siu Sai Wan Salt Water Pumping Station	WSD8	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Heng Fa Chuen Salt Water Pumping Station	WSD9	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Sai Wan Ho Salt Water Pumping Station	WSD10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Quarry Bay Salt Water Pumping Station	WSD11	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Salt Water Pumping Station	WSD12	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sheung Wan Salt Water Pumping Station	WSD13	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kennedy Town Salt Water Pumping Station	WSD14	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
North Point	WSD15	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Central Waterfront	WSD16	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006

- Value in Bold indicates exceedance of relevant criteria.

Table 3.30: Predicted Dissolved Oxygen Concentrations for Scenario 2A

Sensitive Receivers	Assess-ment Point	Minimum Depth-averaged DO level (mgL^-1)						Minimum DO level at bottom layer (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO
Corals
Cape Collinson	CR1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Green Island	CR2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Sandy Bay	CR3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Corals at Junk Bay	CR4	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR5	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR6	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay – Junk Island	CR7	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Ma Wan Fish Culture Zone	F2	5.5	0.0	5.5	3.6	0.0	3.6	5.7	0.0	5.7	2.7	0.0	2.7
Cooling Water Intakes
MTRC Tsing Yi Station	C1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
MTRC Kowloon Station	C2	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
China H.K. City	C3	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Harbour City	C4	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Centre	C5	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Terminal	C6	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Government Premises	C7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
New World Centre	C8	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
East Rail Extension	C9	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Yau Tong Bay Ice Plant	C10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Pamela Youde Nethersole	C11	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Provident Centre	C12	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
City Garden	C13	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Windsor House	C14	5.3	0.1	5.2	3.3	0.1	3.2	5.3	0.1	5.2	2.7	0.3	2.4
Excelsior Hotel and World Trade Centre	C15	5.3	0.9	4.4	3.3	0.7	2.6	5.3	1.2	4.1	2.7	1.6	1.1
Sun Hung Kai Centre	C16	5.3	0.2	5.1	3.3	0.2	3.1	5.3	0.2	5.1	2.7	0.3	2.4
Great Eagle Centre / China Resources Building	C17	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Hong Kong Convention and	C20	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Hong Kong Convention and	C21	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Queensway Government Offices	C22	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Hong Kong and Shanghai Bank	C23	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Prince’s Building Group,	C24	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
MTRC South Intake	C25	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Sha Wan Drive	C26	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Queen Mary Hospital	C27	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
North Point Government Offices	C28	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Taikoo Place	C29	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Cheung Sha Wan Salt Water Pumping Station	WSD2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kowloon South Salt Water Pumping Station	WSD3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Yau Ma Tei Salt Water Pumping Station	WSD4	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Tai Wan Salt Water Pumping Station	WSD5	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Cha Kwo Ling Salt Water Pumping Station	WSD6	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Yau Tong Salt Water Pumping Station	WSD7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Siu Sai Wan Salt Water Pumping Station	WSD8	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Heng Fa Chuen Salt Water Pumping Station	WSD9	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Sai Wan Ho Salt Water Pumping Station	WSD10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Quarry Bay Salt Water Pumping Station	WSD11	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Wan Chai Salt Water Pumping Station	WSD12	5.3	0.1	5.2	3.3	0.1	3.2	5.3	0.1	5.2	2.7	0.1	2.6
Sheung Wan Salt Water Pumping Station	WSD13	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kennedy Town Salt Water Pumping Station	WSD14	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
North Point	WSD15	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Central Waterfront	WSD16	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6

- Value in Bold indicates exceedance of relevant criteria.

Table 3.31: Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 2A

Sensitive Receivers	Assess-ment Point	Maximum TIN Concentration (mgL^-1)						Maximum UIA Concentration (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	TIN elevat-ion	Max. TIN	Back-ground	TIN elevat-ion	Max. TIN	Back-ground	UIA elevat-ion	Max. UIA	Back-ground	UIA elevat-ion	Max. UIA
Corals
Cape Collinson	CR1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Green Island	CR2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Sandy Bay	CR3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Corals at Junk Bay	CR4	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR5	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR6	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay – Junk Island	CR7	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Ma Wan Fish Culture Zone	F2	0.29	0.00	0.29	0.37	0.00	0.37	0.004	0.000	0.004	0.006	0.000	0.006
Cooling Water Intakes
MTRC Tsing Yi Station	C1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
MTRC Kowloon Station	C2	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
China H.K. City	C3	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Harbour City	C4	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Centre	C5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Terminal	C6	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Government Premises	C7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
New World Centre	C8	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
East Rail Extension	C9	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Bay Ice Plant	C10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Pamela Youde Nethersole	C11	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Provident Centre	C12	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
City Garden	C13	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Windsor House	C14	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Excelsior Hotel and World Trade Centre	C15	0.22	0.08	0.30	0.32	0.03	0.35	0.004	0.003	0.007	0.006	0.001	0.007
Sun Hung Kai Centre	C16	0.22	0.01	0.23	0.32	0.01	0.33	0.004	0.001	0.005	0.006	0.000	0.006
Great Eagle Centre / China Resources Building	C17	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C20	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C21	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queensway Government Offices	C22	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong and Shanghai Bank	C23	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Prince’s Building Group,	C24	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
MTRC South Intake	C25	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sha Wan Drive	C26	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queen Mary Hospital	C27	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
North Point Government Offices	C28	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Taikoo Place	C29	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Cheung Sha Wan Salt Water Pumping Station	WSD2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kowloon South Salt Water Pumping Station	WSD3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Yau Ma Tei Salt Water Pumping Station	WSD4	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Tai Wan Salt Water Pumping Station	WSD5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Cha Kwo Ling Salt Water Pumping Station	WSD6	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Salt Water Pumping Station	WSD7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Siu Sai Wan Salt Water Pumping Station	WSD8	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Heng Fa Chuen Salt Water Pumping Station	WSD9	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Sai Wan Ho Salt Water Pumping Station	WSD10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Quarry Bay Salt Water Pumping Station	WSD11	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Salt Water Pumping Station	WSD12	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sheung Wan Salt Water Pumping Station	WSD13	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kennedy Town Salt Water Pumping Station	WSD14	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
North Point	WSD15	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Central Waterfront	WSD16	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006

- Value in Bold indicates exceedance of relevant criteria.

Table 3.32: Predicted Dissolved Oxygen Concentrations for Scenario 2B

Sensitive Receivers	Assess-ment Point	Minimum Depth-averaged DO level (mgL^-1)						Minimum DO level at bottom layer (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO	Back-ground	DO deplet-ion	Min. DO
Corals
Cape Collinson	CR1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Green Island	CR2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Sandy Bay	CR3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Corals at Junk Bay	CR4	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR5	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay	CR6	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Corals at Junk Bay – Junk Island	CR7	5.6	0.0	5.6	4.4	0.0	4.4	5.8	0.0	5.8	3.6	0.0	3.6
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Ma Wan Fish Culture Zone	F2	5.5	0.0	5.5	3.6	0.0	3.6	5.7	0.0	5.7	2.7	0.0	2.7
Cooling Water Intakes
MTRC Tsing Yi Station	C1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
MTRC Kowloon Station	C2	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
China H.K. City	C3	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Harbour City	C4	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Centre	C5	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Ocean Terminal	C6	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Government Premises	C7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
New World Centre	C8	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
East Rail Extension	C9	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Yau Tong Bay Ice Plant	C10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Pamela Youde Nethersole	C11	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Provident Centre	C12	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
City Garden	C13	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Windsor House	C14	5.3	0.1	5.2	3.3	0.1	3.2	5.3	0.1	5.2	2.7	0.3	2.4
Excelsior Hotel and World Trade Centre	C15	5.3	0.9	4.4	3.3	0.7	2.6	5.3	1.2	4.1	2.7	1.6	1.1
Sun Hung Kai Centre	C16	5.3	0.2	5.1	3.3	0.2	3.1	5.3	0.2	5.1	2.7	0.3	2.4
Great Eagle Centre / China Resources Building	C17	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Hong Kong Convention and	C20	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Hong Kong Convention and	C21	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Queensway Government Offices	C22	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Hong Kong and Shanghai Bank	C23	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Prince’s Building Group,	C24	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
MTRC South Intake	C25	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Sha Wan Drive	C26	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Queen Mary Hospital	C27	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
North Point Government Offices	C28	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Taikoo Place	C29	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Cheung Sha Wan Salt Water Pumping Station	WSD2	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kowloon South Salt Water Pumping Station	WSD3	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Yau Ma Tei Salt Water Pumping Station	WSD4	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Tai Wan Salt Water Pumping Station	WSD5	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Cha Kwo Ling Salt Water Pumping Station	WSD6	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Yau Tong Salt Water Pumping Station	WSD7	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.0	2.7
Siu Sai Wan Salt Water Pumping Station	WSD8	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Heng Fa Chuen Salt Water Pumping Station	WSD9	5.9	0.0	5.9	4.5	0.0	4.5	6.1	0.0	6.1	3.6	0.0	3.6
Sai Wan Ho Salt Water Pumping Station	WSD10	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6
Quarry Bay Salt Water Pumping Station	WSD11	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Wan Chai Salt Water Pumping Station	WSD12	5.3	0.1	5.2	3.3	0.1	3.2	5.3	0.1	5.2	2.7	0.1	2.6
Sheung Wan Salt Water Pumping Station	WSD13	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
Kennedy Town Salt Water Pumping Station	WSD14	5.6	0.0	5.6	4.0	0.0	4.0	5.7	0.0	5.7	2.5	0.0	2.5
North Point	WSD15	5.3	0.1	5.2	3.3	0.0	3.3	5.3	0.1	5.2	2.7	0.1	2.6
Central Waterfront	WSD16	5.3	0.0	5.3	3.3	0.0	3.3	5.3	0.0	5.3	2.7	0.1	2.6

- Value in Bold indicates exceedance of relevant criteria.

Table 3.33: Predicted Total Inorganic Nitrogen and Unionised Ammonia Concentrations for Scenario 2B

Sensitive Receivers	Assess-ment Point	Maximum TIN Concentration (mgL^-1)						Maximum UIA Concentration (mgL^-1)
		Dry Season			Wet Season			Dry Season			Wet Season
		Back-ground	TIN elevat-ion	Max. TIN	Back-ground	TIN elevat-ion	Max. TIN	Back-ground	UIA elevat-ion	Max. UIA	Back-ground	UIA elevat-ion	Max. UIA
Corals
Cape Collinson	CR1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Green Island	CR2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Sandy Bay	CR3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Corals at Junk Bay	CR4	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR5	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay	CR6	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Corals at Junk Bay – Junk Island	CR7	0.17	0.00	0.17	0.18	0.00	0.18	0.003	0.000	0.003	0.004	0.000	0.004
Fish Culture Zone
Tung Lung Chau Fish Culture Zone	F1	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Ma Wan Fish Culture Zone	F2	0.29	0.00	0.29	0.37	0.00	0.37	0.004	0.000	0.004	0.006	0.000	0.006
Cooling Water Intakes
MTRC Tsing Yi Station	C1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
MTRC Kowloon Station	C2	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
China H.K. City	C3	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Harbour City	C4	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Centre	C5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Ocean Terminal	C6	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Government Premises	C7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
New World Centre	C8	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
East Rail Extension	C9	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Bay Ice Plant	C10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Pamela Youde Nethersole	C11	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Provident Centre	C12	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
City Garden	C13	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Windsor House	C14	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Excelsior Hotel and World Trade Centre	C15	0.22	0.08	0.30	0.32	0.03	0.35	0.004	0.003	0.007	0.006	0.001	0.007
Sun Hung Kai Centre	C16	0.22	0.02	0.24	0.32	0.01	0.33	0.004	0.001	0.005	0.006	0.000	0.006
Great Eagle Centre / China Resources Building	C17	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Tower / Revenue Tower / Immigration Tower	C18	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Telecom House / Hong Kong Academy for Performing Arts / Shun On Centre	C19	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C20	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong Convention and	C21	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queensway Government Offices	C22	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Hong Kong and Shanghai Bank	C23	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Prince’s Building Group,	C24	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
MTRC South Intake	C25	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sha Wan Drive	C26	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Queen Mary Hospital	C27	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
North Point Government Offices	C28	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Taikoo Place	C29	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
WSD Seawater Intakes
Tsing Yi Salt Water Pumping Station	WSD1	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Cheung Sha Wan Salt Water Pumping Station	WSD2	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kowloon South Salt Water Pumping Station	WSD3	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Yau Ma Tei Salt Water Pumping Station	WSD4	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Tai Wan Salt Water Pumping Station	WSD5	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Cha Kwo Ling Salt Water Pumping Station	WSD6	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Yau Tong Salt Water Pumping Station	WSD7	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Siu Sai Wan Salt Water Pumping Station	WSD8	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Heng Fa Chuen Salt Water Pumping Station	WSD9	0.14	0.00	0.14	0.17	0.00	0.17	0.002	0.000	0.002	0.003	0.000	0.003
Sai Wan Ho Salt Water Pumping Station	WSD10	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Quarry Bay Salt Water Pumping Station	WSD11	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Wan Chai Salt Water Pumping Station	WSD12	0.22	0.01	0.23	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Sheung Wan Salt Water Pumping Station	WSD13	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
Kennedy Town Salt Water Pumping Station	WSD14	0.25	0.00	0.25	0.35	0.00	0.35	0.004	0.000	0.004	0.006	0.000	0.006
North Point	WSD15	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006
Central Waterfront	WSD16	0.22	0.00	0.22	0.32	0.00	0.32	0.004	0.000	0.004	0.006	0.000	0.006

- Value in Bold indicates exceedance of relevant criteria.

3.7.3 Potential Contaminant Release During Dredging

An indication of the likelihood of release of contaminants from the marine mud during dredging is given by the results of the elutriation tests from the laboratory testing conducted under the marine SI for selected sediment sampling stations as shown in Table 3.34. Description of the marine SI is given in Section 4. Sediment samples mixed with a solution, i.e. the ambient seawater collected from the same site, were vigorously agitated during the tests to simulate the strong disturbance to the seabed sediment during dredging. Pollutants absorbed onto the sediment particles will be released and increasing the pollutant concentrations in the solution. The laboratory testing was to analyse the pollutant concentrations in the solution (elutriate). If the contaminant levels are higher in the elutriates in comparison with the blanks (i.e. marine water from the same site), it can be concluded that the contaminants are likely to be released into the marine waters during dredging activities. As there is no existing legislative standard or guideline for individual heavy metal contents in marine waters, the UK Water Quality Standards for Coastal Surface WaterF[10]F have been adopted as the assessment criteria.

The elutriate samples were analyzed for heavy metals, TBT, total PCBs, total PAHs, and chlorinated pesticides (including alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, heptachlor, Aldrin, heptachlor epoxide, endososulfan, p,p’-DDT, p,p’-DDD, p,p’-DDE, endosulfan sulphate).

Table 3.34 show the elutriate testing results for heavy metals, TBT, total PCBs, total PAHs,. The measured levels of all the chlorinated pesticides chemicals were below the detection limit. The laboratory reports on elutriate testing results were provided in Appendix B6.

Table 3.34: Comparison of Marine Sediment Elutriate Test Results with Water Quality Standards

Vibrocore	Sampling Depth		Metals									Total	Total	TBT
No.	From	To	As	Cd	Cr	Cu	Pb	Hg	Ni	Ag	Zn	PCBs	PAHs
	(m)	(m)	µg/l									µg/l	µg/l	µg/l
Water Quality Standards			25^1	2.5^1	15^1	5^1	25^1	0.3^1	30^1	1.9^2	40^1	0.03^2	3.0^3	0.1^4
VC-1A	0	0.9	9.7	<0.2	<1	<1	<1	<0.1	5.4	<1	11	<0.01	<0.20	<0.015
VC-1A	0.9	1.9	<2	0.28	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-1A	1.9	2.9	<2	0.21	<1	<1	<1	<0.1	10	<1	<4	<0.01	<0.20	<0.015
VC-1A	2.9	5.9	<2	<0.2	<1	<1	<1	<0.1	17	<1	<4	<0.01	<0.20	<0.015
VC-1A	Blank		<2	<0.2	<1	<1	1.2	<0.1	2.2	<1	13	<0.01	<0.20	<0.015
VC-3	0	0.9	<2	0.21	<1	1.5	<1	<0.1	2.9	<1	<4	<0.01	<0.20	<0.015
VC-3	0.9	1.9	<2	<0.2	<1	<1	1.1	<0.1	2.8	<1	<4	<0.01	<0.20	<0.015
VC-3	1.9	2.9	33	0.27	<1	<1	<1	<0.1	1.1	<1	<4	<0.01	<0.20	<0.015
VC-3	2.9	5.9	3.8	<0.2	<1	<1	<1	<0.1	1.1	<1	<4	<0.01	<0.20	<0.015
VC-3	Blank		2.1	<0.2	3.6	4.3	1.9	<0.1	1.5	<1	78	<0.01	<0.20	<0.015
VC-5	0	0.9	2.8	0.38	<1	<1	<1	<0.1	2.4	<1	<4	<0.01	<0.20	<0.015
VC-5	0.9	1.9	3	0.23	<1	1.4	<1	<0.1	1.3	<1	<4	<0.01	<0.20	<0.015
VC-5	1.9	2.9	22	0.22	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-5	2.9	5.9	5.4	<0.2	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-5	Blank		<2	<0.2	3.7	3.9	1.5	<0.1	1.5	<1	79	<0.01	<0.20	<0.015
VC-7	0	0.9	13	<0.2	<1	1.4	<1	<0.1	1.3	<1	<4	<0.01	<0.20	<0.015
VC-7	0.9	1.9	30	0.27	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-7	1.9	2.9	<2	<0.2	<1	<1	<1	<0.1	1.7	<1	<4	<0.01	<0.20	<0.015
VC-7	2.9	5.9	<2	0.21	<1	<1	<1	<0.1	1.4	<1	<4	<0.01	<0.20	<0.015
VC-7	Blank		<2	<0.2	3	3	1.2	<0.1	1.5	<1	58	<0.01	<0.20	<0.015
VC-9	0	0.9	<2	0.2	<1	<1	<1	<0.1	2.8	<1	<4	<0.01	<0.20	<0.015
VC-9	0.9	1.9	22	1.2	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-9	1.9	2.9	34	1.1	<1	<1	<1	<0.1	1.1	<1	<4	<0.01	<0.20	<0.015
VC-9	2.9	5.9	<2	0.27	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-9	Blank		<2	<0.2	<1	<1	<1	<0.1	<1	<1	15	<0.01	<0.20	<0.015
VC-11	0	0.9	2.3	1	<1	36	<1	<0.1	11	<1	28	<0.01	<0.20	<0.015
VC-11	0.9	1.9	7.7	0.27	<1	<1	<1	<0.1	1.1	<1	<4	<0.01	<0.20	<0.015
VC-11	1.9	2.9	5.3	<0.2	<1	<1	<1	<0.1	2.2	<1	<4	<0.01	<0.20	<0.015
VC-11	2.9	5.9	<2	<0.2	<1	1.7	<1	<0.1	1.4	<1	<4	<0.01	<0.20	<0.015
VC-11	Blank		<2	<0.2	<1	<1	<1	<0.1	<1	<1	15	<0.01	<0.20	<0.015
VC-13	0	0.9	<2	0.26	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-13	0.9	1.9	7.6	0.28	<1	2.7	<1	<0.1	1.2	<1	<4	<0.01	<0.20	<0.015
VC-13	1.9	2.9	2.6	<0.2	<1	<1	<1	<0.1	1.4	<1	4.3	<0.01	<0.20	<0.015
VC-13	2.9	5.9	<2	<0.2	<1	<1	<1	<0.1	3.1	<1	<4	<0.01	<0.20	<0.015
VC-13	Blank		<2	<0.2	<1	<1	<1	<0.1	<1	<1	15	<0.01	<0.20	<0.015
VC-15	0	0.9	<2	0.32	<1	3.6	<1	<0.1	1.7	<1	6.2	<0.01	<0.20	<0.015
VC-15	0.9	1.9	9.2	0.37	<1	1.9	<1	<0.1	2.1	<1	4.9	<0.01	<0.20	<0.015
VC-15	1.9	2.9	15	0.55	<1	<1	<1	<0.1	1.1	<1	<4	<0.01	<0.20	<0.015
VC-15	2.9	5.9	<2	<0.2	<1	1.8	<1	<0.1	1.8	<1	<4	<0.01	<0.20	<0.015
VC-15	Blank		<2	<0.2	<1	<1	<1	<0.1	<1	<1	14	<0.01	<0.20	<0.015
VC-17	0	0.9	3	0.22	<1	2.1	<1	<0.1	2.8	<1	<4	<0.01	<0.20	<0.015
VC-17	0.9	1.9	27	0.48	<1	2.3	<1	<0.1	5.7	<1	5	<0.01	<0.20	<0.015
VC-17	1.9	2.9	5.4	0.26	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-17	2.9	5.9	2.2	<0.2	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-17	Blank		<2	<0.2	<1	<1	<1	<0.1	<1	<1	16	<0.01	<0.20	<0.015
VC-19	0	0.9	5.4	0.23	<1	1.8	<1	<0.1	2.1	<1	<4	<0.01	<0.20	<0.015
VC-19	0.9	1.9	19	0.61	<1	2.1	<1	<0.1	1.4	<1	<4	<0.01	<0.20	<0.015
VC-19	1.9	2.9	4.5	0.63	<1	1.1	<1	<0.1	1.3	4.8	4.4	<0.01	<0.20	<0.015
VC-19	2.9	5.9	4.7	0.28	<1	1.4	<1	<0.1	2.8	<1	4.6	<0.01	<0.20	<0.015
VC-19	Blank		<2	<0.2	<1	<1	<1	<0.1	<1	<1	16	<0.01	<0.20	<0.015
VC-21	0	0.9	8.5	0.2	<1	<1	<1	<0.1	2.6	<1	4.2	<0.01	<0.20	<0.015
VC-21	0.9	1.9	20	0.4	<1	<1	<1	<0.1	1.2	<1	<4	<0.01	<0.20	<0.015
VC-21	1.9	2.9	19	0.5	<1	<1	<1	<0.1	2.4	<1	9.3	<0.01	<0.20	<0.015
VC-21	2.9	5.9	4.4	0.2	<1	<1	<1	<0.1	<1	2	<4	<0.01	<0.20	<0.015
VC-21	Blank		<2	<0.2	<1	1.7	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-23	0	0.9	3.2	0.2	<1	1.6	<1	<0.1	3.2	<1	<4	<0.01	<0.20	<0.015
VC-23	0.9	1.9	3.6	<0.2	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-23	1.9	2.9	<2	0.22	<1	<1	<1	<0.1	1.3	<1	<4	<0.01	<0.20	<0.015
VC-23	2.9	5.9	<2	<0.2	<1	1.2	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-23	5.9	8.9	2.1	<0.2	<1	2.9	<1	<0.1	9.9	<1	<4	<0.01	<0.20	<0.015
VC-23	Blank		<2	<0.2	<1	1.7	<1	<0.1	<1	<1	19	<0.01	<0.20	<0.015
VC-31	0	0.9	2.1	0.24	<1	3	<1	<0.1	6.5	<1	<4	<0.01	<0.20	<0.015
VC-31	0.9	1.9	<2	0.26	<1	2.1	1.3	<0.1	2	<1	<4	<0.01	<0.20	<0.015
VC-31	1.9	2.9	<2	<0.2	<1	2.2	<1	<0.1	3.1	<1	<4	<0.01	<0.20	<0.015
VC-31	2.9	5.9	<2	<0.2	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-31	5.9	8.9	<2	0.24	<1	<1	<1	<0.1	10	<1	<4	<0.01	<0.20	<0.015
VC-31	Blank		2.1	<0.2	<1	1.7	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-33	0	0.9	2.2	<0.2	<1	<1	<1	<0.1	3.1	<1	<4	<0.01	<0.20	<0.015
VC-33	0.9	1.9	<2	<0.2	<1	<1	<1	<0.1	<1	<1	24	<0.01	<0.20	<0.015
VC-33	1.9	2.9	<2	<0.2	<1	<1	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-33	Blank		<2	<0.2	<1	1.9	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-33B	2.9	5.9	<2	<0.2	<1	<1	<1	<0.1	1.9	<1	<4	<0.01	<0.20	<0.015
VC-33B	5.9	8.9	<2	<0.2	<1	<1	<1	<0.1	2.3	<1	<4	<0.01	<0.20	<0.015
VC-33B	Blank		<2	<0.2	<1	<1	<1	<0.1	<1	<1	9.5	<0.01	<0.20	<0.015
VC-35	0	0.9	<2	0.2	<1	2.5	<1	<0.1	3.3	<1	5.7	<0.01	<0.20	<0.015
VC-35	0.9	1.9	<2	<0.2	<1	<1	<1	<0.1	2	2.6	5.9	<0.01	<0.20	<0.015
VC-35	1.9	2.9	<2	<0.2	<1	<1	<1	<0.1	2.2	<1	<4	<0.01	<0.20	<0.015
VC-35	2.9	5.9	4.5	<0.2	<1	<1	<1	<0.1	2.1	<1	<4	<0.01	<0.20	<0.015
VC-35	5.9	8.9	<2	<0.2	<1	<1	<1	<0.1	1	<1	<4	<0.01	<0.20	<0.015
VC-35	Blank		<2	<0.2	2.3	4.3	<1	<0.1	<1	<1	<4	<0.01	<0.20	<0.015
VC-37	0	0.9	<2	<0.2	1.9	1.5	<1	<0.1	1.6	<1	<4	<0.01	<0.20	<0.015
VC-37	0.9	1.9	2.8	<0.2	<1	2.1	<1	<0.1	2.3	<1	<4	<0.01	<0.20	<0.015
VC-37	1.9	2.9	<2	<0.2	<1	2	<1	<0.1	3	<1	<4	<0.01	<0.20	<0.015
VC-37	2.9	5.9	<2	<0.2	<1	<1	<1	<0.1	2.4	<1	<4	<0.01	<0.20	<0.015
VC-37	5.9	8.9	<2	<0.2	<1	<1	<1	<0.1	1.4	<1	<4	<0.01	<0.20	<0.015
VC-37	Blank		2	<0.2	<1	1.6	1.3	<0.1	1.4	<1	17	<0.01	<0.20	<0.015

Values in bold indicates exceedance of the Water Quality Standard

(1) UK Water Quality Standard

(2) USEPA salt water criterion

(3) Australian and New Zealand Guidelines for Fresh and Marine Waters

(4) Michael H. Salazar and Sandra M. Salazar (1996). “Mussels as Bioindicators: Effects of TBT on Survival, Bioaccumulation, and Growth under Natural Conditions” in Organotin, edited by M. A. Champ and P. F. Seligman. Chapman & Hall, London

(5) WQO for Victoria Harbour WCZ under the WPCO

Table 3.34 showed that the concentrations of arsenic, copper and silver in the elutriate samples exceeded the assessment criteria. The highest concentrations of arsenic (34mg/l), copper (36mg/l) and silver (4.8mg/l) were recorded at Station VC9, VC11 and VC19, respectively. The levels of cadmium, chromium, lead, mercury and nickel in the elutriate samples complied well with the relevant water quality criteria.

All exceedance of the heavy metal concentrations are found at samples locating in the north portion of the proposed pipeline, except a marginally exceedence of silver concentration is found at Station VC35. The marginally exceedance is expected to cause minimal water quality impacts since the potential release of silver from sediment will be rapidly diluted by large volume of marine water within the dredging site.

The elutriate test results of TBT, total PCBs and total PAHs do not indicate any levels higher than the blank results nor the water quality criteria. It is therefore concluded that adverse water quality impacts due to the potential release of TBT, total PCBs and total PAHs from the sediment are not expected during the dredging activities.

Chlorinated pesticides including alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, heptachlor, Aldrin, heptachlor epoxide, endososulfan, p,p’-DDT, p,p’-DDD, p,p’-DDE, endosulfan sulphate, were also measured in both the sediment and elutriate samples. The laboratory results show that these pesticides were not detected in any of the sediment and elutriate samples. All the measured values are below the detection limit of 0.5 mg/kg for sediment and 0.1 mg/l for elutriate. Also, the elutriate test results do not indicate any levels higher than the blank results which indicated that the impact from the potential release of pesticides during dredging will not be an issue of concern.

Based on the detected highest concentrations, the required dilutions to meet the assessment criteria were calculated to be 1.4 for arsenic, 7.2 for copper and 2.5 for silver.

In order to determine the maximum dimensions of mixing zones for the contaminants including arsenic, copper, and silver, cconservative tracers at Source A was introduced into the Delft3D-WAQ model for Scenario 1 model runs to estimate the dilution that could be generated by the tidal flows. Source A was selected as a representative source location for the mixing zone estimations since the exceedance of the heavy metal concentrations are mainly found at samples locating in the north portion of the proposed pipeline as mentioned above.

It was also assumed that all of the heavy metals concentrations in the sediment will be released to the water. These are conservative assumptions and will likely result in an over-prediction of the potential impacts. The calculation was performed using the highest levels of heavy metals measured in the sediment elutriate samples (Table 3.34). The highest levels of arsenic, copper and silver were recorded at Stations VC9, 11 and 19 respectively.

The contour plots of maximum tracer concentrations predicted for the entire simulation period during dry and wet seasons are shown in Appendices B7a and B7b. The mixing zone for arsenic, copper and silver is within 200m, 1500m and 250m, respectively. By examining those Stations with exceedance in Table 3.34, there is no WSRs identified within the mixing zones for arsenic and silver and only WSR WSD5 is identified within the mixing zone of copper. It is noted that the WSR WSD5 is a seawater intake for flushing purpose. Furthermore, any potential non-compliance of water quality criteria for copper is limited to a period when the dredging activities are undertaken within the vicinity of Station VC11 only.

The maximum tracer concentrations (Appendix B6) should be considered as the areas which envelop the moving plumes over the entire simulation period but not as the actual maximum plume size. The predicted maximum instantaneous mixing zone is, in fact, much smaller. Moreover, it is expected that any release of heavy metals during dredging will be quickly diluted by the large volume of marine water within the dredging site. The release of contaminants will also be minimized by the use of closed grab dredger. Therefore, impact on the marine ecological and fisheries resources from the potential contaminant release would be very limited. As such, it is considered that long-term off-site marine water quality impact is unlikely and any local water quality impact will be transient.

Hydrostatic/Commissioning Tests of the Gas Pipeline System

Effluent from the hydrostatic test of gas pipelines would be subjected to sedimentation to ensure compliance with the discharge requirements stipulated in TM-DSS. High SS concentration in marine water would lead to associated reduction in DO levels. Proper practice and management should be strictly followed to prevent water with high level SS from entering the surrounding waters. With the implementation of appropriate measures to control water discharge from hydrostatic test, disturbance of water bodies would be localised and deterioration in water quality would be minimal. Effluent from hydrostatic tests would comply with the standards for effluent discharged into the inshore waters or marine waters of the Victoria Harbour WCZ as shown in Tables 9a and 9b of the TM-DSS provided the recommended mitigation measures detailed in Section 3.8 were properly implemented.

3.7.4 Surface Runoff, Sewage and Wastewater from Construction Activities

Construction run-off will cause physical, chemical and biological effects. The physical effects will arise from any increase in SS from the construction site that blocks drainage channels and causes local flooding when heavy rainfall occurs. High SS concentrations in marine water would also lead to associated reduction in DO levels.

Proper site practice and good site management should be strictly followed to prevent run-off water with high level of SS from entering the surrounding waters. With the implementation of appropriate measures to control run-off from the construction site, disturbance of water bodies would be localised and deterioration in water quality would be minimal. Unacceptable impacts on the water quality were not expected provided that the recommended measures described in Section 3.8 were properly implemented.

Provided that good construction practices are observed to ensure that litter, fuels, and solvents are managed, stored and handled properly, effects on water quality from general construction activities would be minimal.

Based on the Sewerage Manual, Part I, 1995 of the Drainage Services Department (DSD), the global unit flow factor for employed population of 0.06 m³ per worker per day and commercial activities in year 2012 of 0.29 m³ per worker per day were used to estimate the sewage generation from the construction site. The total sewage production rate was estimated at 0.35 m³ per worker per day. With every 100 construction workers working simultaneously at the construction site, a total of about 35 m³ of sewage would be generated per day. The sewage should not be allowed to discharge directly into the surrounding water body without treatment. Chemical toilets and subsequently on-site sewer should be deployed at the construction site to collect and handle sewage from workers.

3.8 Mitigation of Adverse Environmental Impact

3.8.1 Construction Phase

3.8.1.1 Dredging

Although exceedance of dissolved oxygen levels were predicted at various water quality sensitive receivers in Victoria Harbour and near Ma Wan fish culture zone during wet season, the ambient dissolved oxygen levels at Victoria Harbour and near Ma Wan fish culture zone during wet season did not comply with the Water Quality Objectives criteria for marine water and fish culture zones, respectively. As the predicted maximum decrease of dissolved oxygen levels is trivial, implication of adverse water quality impact is therefore minimal. Limiting dredging to dry season only is therefore not considered as an effective mitigation measure to ensure the Water Quality Objectives Criteria for dissolved oxygen to be complied with.

Although adverse water quality impact is not predicted during the construction phase, implementation of the following mitigation measures is recommended to minimise the potential SS impact from dredging activities:

¡ Dredging shall be carried out by closed grab dredger to minimize release of sediment and other contaminants during dredging;

¡ The maximum production rate for dredging from the seabed for installation of the submarine gas pipelines shall not be more than 4,000m³ per day (and no more than 1 closed grab dredger); and

¡ Deployment of frame type silt curtain to fully enclose the grab while dredging works are in progress. The frame type silt curtain shall be extended to the seabed to cover the entire water column to minimize the potential SS impact. An illustration of a typical configuration of frame type silt curtain is shown in Figure 3.10.

The frame type silt curtain should be designed to enclose local pollution caused by the grab dredger and suspended by a steel frame mounted on the grab dredger and floating on water. This frame type silt curtain should be fabricated from permeable, durable, abrasion resistant membrane like geotextiles and be mounted on a floating boom structure. The frame type silt curtain should also extend to the seabed to cover the entire water column. Steel chain or ballast should be attached to the bottom of the silt curtain. Mid-ballast may be added as necessary. The structure of the silt curtain should be maintained by metal grids. The frame type silt curtain should be capable or reducing sediment loss to outside by a factor of 4 (or about 75%). This SS reduction factor have been adopted in the Laying of Western Cross Harbour Main and Associated Land Mains from West Kowloon to Sai Ying Pun Environmental Impact Assessment Study in 2007.

Other mitigation measures that shall be undertaken during dredging include:

¡ 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;

¡ the speed of all vessels shall be controlled within the works area to prevent propeller wash from stirring up the seabed sediments;

¡ all barges / dredgers used shall be fitted with tight fitting seals to their bottom openings to prevent leakage of material;

¡ construction activities shall not cause foam, oil, grease, scum, litter or other objectionable matter to be present on the water within the site or dumping grounds;

¡ barges or hopper shall not be filled to a level that will cause the overflow of materials or polluted water during loading or transportation; and

¡ before commencement of dredging works, the holder of the Environmental Permit shall submit detailed proposal of the design and arrangement of the frame type silt curtain to EPD for approval.

3.8.1.2 Effluent from Hydrostatic/Commissioning Tests of the Gas Pipeline System

Dosing of chemicals into the water for testing shall be prohibited. Water used for testing shall be reused as far as possible (e.g. water spray for dust suppression on site). A discharge licence under the WPCO shall be applied by the Contractor from EPD for discharging effluent from the construction site. To ensure compliance with the standards for effluent discharged into the inshore waters or marine waters of Victoria Harbour WCZ as shown in Tables 9a and 9b of the TM-DSS, sedimentation tanks with sufficient capacity (determining factors on capacity include retention time, actual design and operation etc.), constructed from pre-formed individual cells of approximately 6 to 8 m³ capacities, shall be adopted for settling the effluent prior to disposal. The system capacity shall be flexible and able to handle multiple inputs from a variety of sources and particularly suited to applications where the influent is pumped.

3.8.1.3 Surface Runoff, Sewage and Wastewater from Construction Activities

Appropriate measures shall be implemented to control runoff and prevent high loads of SS from entering the marine environment. Proper site management is essential to minimise surface runoff and sewage effluents.

Construction site runoff shall be prevented or minimised in accordance with the guidelines stipulated in the EPD's Practice Note for Professional Persons, Construction Site Drainage (ProPECC PN 1/94). All discharges from the construction site shall be controlled to comply with the standards for effluents discharged into the Victoria Harbour WCZ under the TM-DSS. Good housekeeping and stormwater best management practices, as detailed below, shall be implemented to ensure all construction runoff complies with WPCO standards and no unacceptable impact on the WSRs as a result of construction of the proposed submarine gas pipelines.

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.

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

All vehicles and plant shall 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 located wheel washing bay shall be provided at every site exit, and wash-water shall 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 shall be paved with sufficient backfill toward the wheel-wash bay to prevent vehicle tracking of soil and silty water to public roads and drains.

Precautions shall be taken at any time of year when rainstorms are likely. Actions shall be taken when a rainstorm is imminent or forecast. Actions to be taken during or after rainstorms are summarised in Appendix A2 of ProPECC PN 1/94. Particular attention shall be paid to the control of silty surface runoff during storm events, particularly for areas located near steep slopes.

Fuel tanks and storage areas shall be provided with locks and be located 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 the coastal waters of the Victoria Harbour, Western Buffer and Eastern Buffer WCZs.

Portable chemical toilets would be used to handle construction workforce sewage prior to discharge to the existing trunk sewer. Sufficient numbers of portable toilets shall be provided by a licensed contractor to serve the construction workers. The Contractor shall also be responsible for waste disposal and maintenance practices.

3.9 Evaluation of Residual Impacts

Predicted changes for DO by the subject Project are small (maximum depletion of 0.1 mgL^-1) and within the ranges of natural variations experienced in the study area, in particular that predicted changes for DO is 0.0mgL^-1 in Water Sensitive Receivers of Corals and Fish Culture Zones which is effectively no deterioration.  However, as ambient depth-averaged DO levels in wet season recorded in Victoria Harbour and Tung Lung Chau and Ma Wan Fish Culture Zones are low and did not comply with the water quality objectives criteria, this inevitably resulted that the predicted minimum DO values for the subject Project in wet season at various WSRs in Victoria Harbour and Ma Wan Fish Culture Zone would not be able to meet with the water quality objectives criteria.  As the predicted changes for DO by the subject project are small, therefore, no adverse residual water quality impact is expected.

The following points should be noted with reference to section 4.4.3 (a) and (b) of EIAO-TM with regard to the residual water quality impact at these WSRs:

Evaluation Criteria	Water Quality Sensitive Receivers
	Fish Culture Zones (F1 and F2)	Cooling Water Intakes (C2 to C29)	WSD Seawater Intakes (WSD5 to 7, 10 to 12, 15 and 16)
Effects on public health and health of biota or risk to life	DO depletion was not predicted and adverse effect on the FCZs is not anticipated.	DO depletion was either not predicted or predicted to be minor and adverse effect on the cooling water intakes is not anticipated.	DO depletion was either not predicted or predicted to be minor and adverse effect on the seawater intakes is not anticipated.
The magnitude of the adverse environmental impacts	Exceedance of the DO WQO is minor and is due to low ambient DO levels which did not comply with the DO WQO. DO depletion was not predicted. Impact to the FCZs is not anticipated.	Exceedance of the DO WQO is minor and is due to low ambient DO levels which did not comply with the DO WQO. DO depletion was either not predicted or predicted to be minor. Impact to the cooling water intakes would be low.	Exceedance of the DO WQO is minor and is due to low ambient DO levels which did not comply with the DO WQO. DO depletion was either not predicted or predicted to be minor. Impact to the seawater intakes would be low.
The geographic extent of the adverse environmental impacts	As indicated in Appendix B5, DO depletion was not predicted at FCZs. Low ambient DO levels were recorded at part of Victoria Harbour, Eastern and Western Buffer WCZs.	As indicated in Appendix B5, DO depletion was minor and confined to coastal area at Wan Chai. Low ambient DO levels were recorded at part of Victoria Harbour, Eastern and Western Buffer WCZs.	As indicated in Appendix B5, DO depletion was minor and confined to coastal area at Wan Chai. Low ambient DO levels were recorded at part of Victoria Harbour, Eastern and Western Buffer WCZs.
The duration and frequency of the adverse environmental impacts	DO depletion was not predicted. Exceedance of the DO WQO by the ambient DO levels is occasional during the wet seasons in 2007and 2008.	DO depletion was either not predicted or predicted to be minor. Exceedance of the DO WQO by the ambient DO levels is occasional during the wet seasons in 2007and 2008.	DO depletion was either not predicted or predicted to be minor. Exceedance of the DO WQO by the ambient DO levels is occasional during the wet seasons in 2007and 2008.
The likely size of the community or the environment that may be affected by the adverse impacts	As indicated in Appendix B5, DO depletion was not predicted at FCZs.	As indicated in Appendix B5, DO depletion was minor and confined to coastal area at Wan Chai.	As indicated in Appendix B5, DO depletion was minor and confined to coastal area at Wan Chai.
The degree to which the adverse environmental impacts are reversible or irreversible	DO depletion was not predicted.	DO depletion was either not predicted or predicted to be minor. Minor DO depletion are completely reversible as SS will settle out in the water column.	DO depletion was either not predicted or predicted to be minor. Minor DO depletion are completely reversible as SS will settle out in the water column.
The ecological context	No adverse impact is predicted.	No adverse impact is predicted.	No adverse impact is predicted.
The degree of disruption to site of cultural heritage	No adverse impact is predicted.	No adverse impact is predicted.	No adverse impact is predicted.
International and regional importance	No adverse impact is predicted.	No adverse impact is predicted.	No adverse impact is predicted.
Both the likelihood and degree of uncertainty of adverse environmental impacts	No adverse impact is predicted.	No adverse impact is predicted.	No adverse impact is predicted.

Regarding compliance with relevant established principles and criteria, provided the recommended mitigation measures are implemented, no unacceptable residual cumulative water quality impact due to construction of the submarine gas pipelines as well as the other concurrent marine works is expected.

Hydrostatic test of the gas pipeline system would lead to effluent containing elevated concentrations of SS that would enter into the surrounding water. It was however expected that the above water quality impact would be temporary and localised during construction only. Provided the recommended mitigation measure is implemented and the effluent discharge complied with the TM-DSS standards, no unacceptable residual water quality impact due to effluent arising from hydrostatic test is expected.

General construction activities associated with the construction of the submarine gas pipelines would lead to construction site runoff containing elevated concentrations of SS and associated contaminants that would enter into the marine water. It was however expected that the above water quality impacts would be temporary and localised during construction only. Provided the recommended mitigation measures are implemented and all construction site/works area discharges complied with the TM-DSS standards, no unacceptable residual water quality impact due to construction of the submarine gas pipelines is expected.

3.10 Environmental Monitoring and Audit

Adverse water quality impact was not predicted during the construction and operation phase of the Project. Nevertheless, appropriate mitigation measures are recommended to minimize potential water quality impacts. Water quality monitoring and audit would be required to obtain a robust, defensible database of baseline information of water quality before construction, and thereafter, to monitor any variation of water quality from the baseline conditions and exceedances of WQOs at sensitive receivers during construction and to ensure that the recommended mitigation measures are implemented properly. Details of the water quality monitoring and audit programme and the Event and Action Plan are provided in the stand-alone EM&A Manual.

3.11 Summary

The water quality impact during the proposed dredging works for installation of submarine gas pipelines has been quantitatively assessed using the Delft3D Model. Suspended solids are identified as the most critical water quality parameter during the dredging operations. The worst-case scenarios for the dredging works have been assessed and adverse water quality impact was not predicted. Nevertheless, the implementation of the appropriate mitigation measures could effectively minimize any potential water quality impacts upon seawater and cooling water intakes. There would be no unacceptable residual water quality impact due to the proposed dredging works. An environmental monitoring and audit programme is proposed to ensure that all the recommended mitigation measures are implemented properly.

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[1] Territory Development Department (July 2001).  Agreement No. CE 74/98, Wan Chai Development Phase II, Comprehensive Feasibility Study, Environmental Impact Assessment Report, Volume I – Text

[2] Hawker, D. W. and Connell, D. W. (1992). “Standards and Criteria for Pollution Control in Coral Reef Areas” in Connell, D. W and Hawker, D. W. (eds.), Pollution in Tropical Aquatic Systems, CRC Press, Inc.

[3] Mott Connell (2007), Laying of Western Cross Harbour Main and Associated Land Mains from West Kowloon to Sai Ying Pun, Final EIA Report

[4] Maunsell Consultants Asia Ltd. (2001), Environmental Impact Assessment for Tai Po Sewage Treatment Works – Stage V, Final EIA Report, For Drainage Services Department, Hong Kong SAR Government.

[5] Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities (EIA-173/2009)

[6] Water Qaulity Modelling Methodology Paper, Installation of Submarine Gas Pipelines and Associated Facilities from To Kwa Wan to North Point for Former Kai Tak Airport Development - EIA

[7] Atkins China Ltd (2001), Central Reclamation, Phase III Studies, Site Investigation, Design and Construction. Final EIA Report, For Civil Engineering Department, Hong Kong SAR Government

[8] Mott MacDonald (1991), Contaminated Spoil Management Study, Final Report, Volume 1.

[9] ERM-Hong Kong Ltd (1997). Environmental Impact Assessment for the Disposal of Contaminated Mud in the East Sha Chau Marine Borrow Pit. Final EIA Report, For Civil Engineering Department, Hong Kong SAR Government.

^[10] ERM-Hong Kong, Ltd. (January 1997). Environmental Quality Standards and Assessment Levels for Coastal Surface Water (from HMIP (1994) Environmental Economic and BPEO Assessment Principals for Integrated Pollution Control). (Source: Environmental Impact Assessment Study for Disposal of Contaminated Mud in the East Shau Chau Marine Borrow Pit)