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This report takes into account the particular It is not intended for and should
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Ove Arup & Partners
Hong Kong Ltd 80 Tat Chee Avenue Kowloon Tong Kowloon Hong Kong |
6.1.1 The entire Hong Kong waters are divided into ten Water Control Zones (WCZs) and four supplementary WCZs under the Water Pollution Control Ordinance (WPCO) (CAP 358). Each WCZ has a designated set of statutory Water Quality Objectives (WQOs) designed to protect the inland and/or marine environment and its users. The Study Area is close to Victoria Harbour and Junk Bay WCZs. Tables 6.1a and 6.1b summarise the corresponding WQOs.
Table 6.1a: Water Quality Objectives for Victoria Harbour Water Control Zone
|
Parameters |
Water Quality Objective |
WCZ |
|
Aesthetic Appearance |
No objectionable odour or discolouration
of the water; No visible rubbish; No mineral oil; No
lasting foam. |
Whole zone |
|
Bacteria |
The level of Escherichia coli should not 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. |
Inland waters |
|
Colour |
Human activity
should not cause the colour of water to exceed 50 Hazen Units. |
Inland waters |
|
Dissolved Oxygen (DO) |
Within 2 m of bottom: not less than 2 mg/L for 90% samples; Depth average: not less than 4 mg/L for 90% samples |
Marine waters |
|
Rest of water column: not less than 4
mg/L |
Inland
waters |
|
|
pH |
Between 6.5 - 8.5; change due to waste discharge not to
exceed 0.2 |
Marine waters |
|
Temperature |
Change due to waste discharge not to
exceed 2.0 °C |
Whole zone |
|
Salinity |
No more than 10% by change due to waste
discharge |
Whole zone |
|
Suspended Solids (SS) |
Change due to waste discharge not to
exceed 30%; No cause the accumulation of suspended
solids which may adversely affect aquatic community |
Marine waters |
|
Ammonia |
Annual mean for un-ionized ammoniacal
nitrogen level not to exceed 0.021 mg/l |
Whole zone |
|
Nutrients |
Annual mean for inorganic nitrogen level not to exceed 0.4 mg/l |
Marine waters |
|
5-day Biochemical Oxygen Demand (BOD5) |
Not to exceed 5 mg/l |
Inland waters |
|
Chemical Oxygen Demand (COD) |
Not to exceed 30 mg/l |
Inland waters |
|
Toxicants |
Not to be present at levels producing
significant toxic effect |
Whole zone |
Table 6.1b: Water Quality Objectives for
Junk Bay Water Control Zone
|
Parameters |
Water Quality Objective |
WCZ |
|
Offensive Odour, Tints |
Not to be present |
Whole zone |
|
Visible foam, oil scum, litter |
Not to be present |
Whole zone |
|
Dissolved Oxygen (DO) within 2 m of the
seabed |
Not less than 2.0 mg/L for 90% of samples |
Marine waters |
|
Depth-averaged DO |
Not less than 4.0 mg/L for 90% of samples |
Marine waters excepting fish culture
subzones |
|
Not less than 5.0 mg/L for 90% of samples |
Fish culture subzones |
|
|
Not less than 4.0 mg/L |
Inland waters |
|
|
5-Bay Biochemical Oxygen Demand (BOD5) |
Change due to waste discharges not to
exceed 5 mg/L |
Inland waters |
|
Chemical Oxygen Demand (COD) |
Change due to waste discharges not to
exceed 30 mg/L |
Inland waters |
|
pH |
To be in the range of 6.5 - 8.5, change
due to waste discharges not to exceed 0.2 |
Marine waters |
|
To be in the range of 6.0 - 9.0 |
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 waste discharges and shall not affect aquatic communities |
Marine waters |
|
Change due to waste discharges not to
exceed 25 mg/L of annual median |
Inland waters |
|
|
Unionised Ammonia (UIA) |
Annual mean not to exceed 0.021 mg/L as
unionised form |
Whole zone |
|
Nutrients |
Shall not cause excessive algal growth |
Marine waters |
|
Total Inorganic Nitrogen (TIN) |
Annual mean depth-averaged inorganic
nitrogen not to exceed 0.3 mg/L |
Marine waters |
|
Dangerous substances |
Should not attain such levels as to
produce significant toxic effects in humans, fish or any other aquatic
organisms |
Whole zone |
|
Waste discharges should not cause a risk
to any beneficial use of the aquatic environment |
Whole zone |
|
|
Bacteria |
Not exceed 610 per 100ml, calculated as
the geometric mean of all samples collected in one calendar year |
Secondary contact recreation subzones and
fish culture 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 |
Inland waters |
|
|
Colour |
Change due to waste discharges not to
exceed 50 Hazen units |
Inland waters |
Technical Memorandum for Effluents Discharge into Drainage and Sewerage Systems, Inland & Coastal Waters (TM-DSS)
6.1.2 Apart from the WQOs,
Section 21 of the WPCO also specifies the limits to control the physical,
chemical and microbial parameters for effluent discharges into drainage and
sewerage system at both inland and coastal waters under the Technical
Memorandum for Effluents Discharged into Drainage and Sewerage Systems, Inland
and Coastal Waters (TM-DSS). The discharge limits vary with the effluent flow
rates. Sewerage from the proposed development should comply with the
standards for effluent discharged into drainage and sewerage systems. Table 6.2a
and 6.2b summarise the standards for effluent discharged into marine waters of Victoria
Harbour WCZ and Junk Bay WCZ
respectively.
Table 6.2a: Standards for effluents discharged into the marine waters of Victoria Harbour Water Control Zone
|
Flow Rate (m3/day) |
≤10 |
>10 and ≤200 |
>200 and ≤400 |
>400 and ≤600 |
>600 and ≤800 |
>800 and ≤1000 |
>1000 and
≤1500 |
>1500 and
≤2000 |
>2000 and
≤3000 |
>3000 and
≤4000 |
>4000 and
≤5000 |
>5000 and
≤6000 |
|
pH (pH units) |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
6-10 |
|
Temperature (oC) |
45 |
45 |
45 |
45 |
45 |
45 |
45 |
45 |
45 |
45 |
45 |
45 |
|
Colour (lovibond units) (25mm cell length) |
4 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
|
Suspended Solids |
700 |
600 |
600 |
500 |
375 |
300 |
200 |
150 |
100 |
75 |
60 |
40 |
|
BOD5 |
700 |
600 |
600 |
500 |
375 |
300 |
200 |
150 |
100 |
75 |
60 |
40 |
|
COD |
1500 |
1200 |
1200 |
1000 |
700 |
600 |
400 |
300 |
200 |
100 |
100 |
85 |
|
Oil & Grease |
50 |
50 |
50 |
30 |
25 |
20 |
20 |
20 |
20 |
20 |
20 |
20 |
|
Iron |
20 |
15 |
13 |
10 |
7.5 |
6 |
4 |
3 |
2 |
1.5 |
1.2 |
1 |
|
Boron |
6 |
5 |
4 |
3.5 |
2.5 |
2 |
1.5 |
1 |
0.7 |
0.5 |
0.4 |
0.3 |
|
Barium |
6 |
5 |
4 |
3.5 |
2.5 |
2 |
1.5 |
1 |
0.7 |
0.5 |
0.4 |
0.3 |
|
Mercury |
0.1 |
0.1 |
0.05 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
|
Cadmium |
0.1 |
0.1 |
0.05 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
0.001 |
|
Other toxic metals individually |
2 |
1.5 |
1 |
0.8 |
0.6 |
0.5 |
0.32 |
0.24 |
0.16 |
0.12 |
0.1 |
0.1 |
|
Total toxic metals |
4 |
3 |
2 |
1.6 |
1.2 |
1 |
0.64 |
0.48 |
0.32 |
0.24 |
0.2 |
0.14 |
|
Cyanide |
1 |
0.5 |
0.5 |
0.5 |
0.4 |
0.3 |
0.2 |
0.1 |
0.1 |
0.08 |
0.06 |
0.04 |
|
Phenols |
0.5 |
0.5 |
0.5 |
0.3 |
0.3 |
0.2 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
|
Sulphide |
5 |
5 |
5 |
5 |
5 |
5 |
2.5 |
2.5 |
1.5 |
1 |
1 |
0.5 |
|
Total residual chlorine |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
|
Total nitrogen |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
50 |
|
Total phosphorus |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
5 |
|
Surfactants (total) |
30 |
20 |
20 |
20 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
|
E. coli (counts/100 ml) |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
5,000 |
Notes:
[1] Extracted from Table 10b of “Technical Memorandum for Effluents Discharged into Dra
