5.
WATER QUALITY
5.1
Introduction
5.1.1
This section presents the assessment of
potential water quality impacts that could result from the construction and
operation phases of the CWB & IECL.
All construction works for the Project will be land-based and, thus,
direct impacts on marine water quality will not arise.
5.2
Environmental Legislation, Policies, Plans, Standards and Criteria
5.2.1
The Water Pollution Control Ordinance (Cap.
358) provides the major statutory framework for the protection and control of
water quality in
Table 5.1 Summary of Water
Quality Objectives for the
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 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 |
Dissolved Oxygen
(DO) within 2 m of the seabed |
Not less than 2.0 mg L-1 for 90% of
samples |
Marine waters |
Depth-averaged DO |
Not less than 4.0 mg L-1 for 90%
of samples |
Marine waters |
Dissolved Oxygen |
Not less than 4.0 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 |
|
Not to exceed the range of 6.0 - 9.0 due to
human activity |
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 |
Not to raise the ambient level by 30% caused
by human activity |
Marine waters |
|
Annual median not to exceed 25 mg L-1
due to human activity |
Inland waters |
Ammonia |
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 |
BOD5 |
Not to exceed 5 mg L-1 |
Inland waters |
Chemical Oxygen
Demand |
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).
5.2.2 Besides setting the WQOs, the WPCO 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) was issued under the WPCO
which 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.
Wastewater from the proposed construction activities should comply with
the TM standards for effluents discharged into the inshore waters of Victoria
Harbour WCZ (Table 9a of the TM), or for effluents discharged into foul sewers
leading into Government sewage treatment plants (Table 1 of the TM).
5.2.3
In addition to the WQOs set under the WPCO, the
Water Supplies Department has specified a set of seawater quality criteria for
flushing water (Table 5.2). The relevant criterion for suspended solids
(SS) is less than 10 mg L-1.
Table 5.2 WSD
Standards at Seawater Intakes
Parameter (in mg L-1 unless otherwise stated) |
WSD Target Limit |
Colour (HU) |
<
20 |
Turbidity (NTU) |
<
10 |
Threshold Odour Number
(odour unit) |
<
100 |
Ammoniacal Nitrogen |
<
1 |
Suspended Solids |
<
10 |
Dissolved Oxygen |
>
2 |
Biochemical Oxygen Demand |
<
10 |
Synthetic Detergents |
<
5 |
E. coli (number per 100 mL) |
<
20,000 |
5.2.4
A practice note (PN) 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 constructions, acid
cleaning, etching and pickling wastewater, and wastewater from site facilities.
Practices given in the PN should be followed as far as possible during
construction to minimise the water quality impact due to construction site
drainage.
5.2.5
Annexes
6 and 14 of
the EIAO-TM provide criteria and general guidelines to be used in assessing
water quality issues.
5.3
Description of the Environment
5.3.1
The marine water quality in Victoria Harbour is
routinely monitored by the EPD. The
monitoring stations of most relevance to the study area are VM4, VM5 and VM6
located in the central harbour area. A
summary of the monitoring data for these three stations in 1998 is provided in
Table 5.3 ([1]).
5.3.2
The water quality monitoring data for 1998
indicates that the dissolved oxygen content in the middle of Victoria Harbour
was generally lower than other parts of the harbour. It was reported that the water quality at stations VM5 and VM6
was subject to the direct impact of sewage discharges from sewage
outfalls. The depth-averaged dissolved
oxygen (DO) at stations VM4, VM5 and VM6 in 1998 showed non-compliance with the
WQO, whereas the bottom DO showed compliance with the WQO for all three
stations. A reduction in the
depth-averaged DO level is observed at Station VM5, in contrast to the results
for 1997 that comply with the WQOs.
5.3.3
The high levels of Total Kjeldahl Nitrogen and
Total Nitrogen that were observed in 1997 at stations VM4, VM5 and VM6 also
prevailed in 1998. The level of E. coli remained largely similar to that
in 1997, except VM6 where this level was found to be reduced by about 50%. As for 1997, the levels of Total Inorganic
Nitrogen (TIN) at stations VM4, VM5 and VM6 showed non-compliance with the WQO
during 1998. A slight increase in the
annual mean of TIN was observed in 1998.
All three stations complied with the WQO for unionised ammonia in 1998
despite a slight elevation of unionised ammonia.
Table 5.3 Summary Statistics of EPD Marine
Water Quality data in Victoria Harbour WCZ for 1998
Determinant |
|
Victoria Harbour (Central) |
||
|
|
VM4 |
VM5 |
VM6 |
Number of samples |
|
12 |
12 |
12 |
Temperature (°C) |
|
23.7 (17.2
- 32.4) |
23.3 (17.1
– 27.8) |
23.3 (17.1
– 27.6) |
Salinity (ppt) |
|
30.9 (28.1
- 33.5) |
30.8 (27.3
– 33.2) |
30.6 (26.8
– 33.1) |
Dissolved Oxygen (mg L-1) |
Surface |
4.8 (3.1
- 6.5) |
4.8 (3.0
– 6.5) |
4.9 (2.9
– 6.8) |
Bottom |
4.4 (2.7
– 6.3) |
4.2 (2.8
– 6.4) |
4.2 (2.0
– 6.0) |
|
Dissolved Oxygen (% Saturation) |
Surface |
96 (49
– 93) |
68 (45
– 97) |
70 (46
– 99) |
Bottom |
64 (43
– 80) |
59 (41
– 80) |
59 (29
– 75) |
|
pH |
|
7.9 (7.4
– 8.2) |
7.5 (6.6
– 8.1) |
7.8 (7.2
– 8.2) |
Secchi Disc Depth (m) |
|
2.5 (1.8
– 3.5) |
2.2 (1.7
– 3.0) |
2.2 (1.0
– 3.0) |
Turbidity (NTU) |
|
4.3 (2.9
– 6.7) |
4.5 (3.1-
5.9) |
4.4 (2.8
– 6.1) |
Suspended Solids (mg L-1) |
|
4.6 (2.6
– 10.5) |
4.6 (2.2
– 8.0) |
4.7 (1.9
– 7.6) |
5-day Biochemical Oxygen Demand
(mg L-1) |
|
1.0 (0.7
– 1.4) |
1.2 (0.5
– 2.3) |
1.2 (0.5
– 1.8) |
Ammoniacal Nitrogen (mg L-1) |
|
0.31 (0.12
– 0.49) |
0.31 (0.06
– 0.50) |
0.31 (0.12
– 0.45) |
Unionised Ammonia (mg L-1) |
|
0.010 (0.003
– 0.022) |
0.007 (0.003
– 0.020) |
0.008 (0.004
– 0.019) |
Nitrite Nitrogen (mg L-1) |
|
0.02 (0.01
– 0.04) |
0.02 (0.01
– 0.04) |
0.02 (0.01
– 0.04) |
Nitrate Nitrogen (mg L-1) |
|
0.10 (0.04
– 0.20) |
0.11 (0.04
– 0.25) |
0.11 (0.04
– 0.25) |
Total Inorganic Nitrogen (mg L-1) |
|
0.43 (0.23
– 0.72) |
0.45 (0.21
– 0.72) |
0.44 (0.24
– 0.67) |
Total Kjeldahl Nitrogen (mg L-1) |
|
1.11 (0.84
– 1.43) |
1.09 (0.76
– 1.47) |
1.08 (0.71
– 1.40) |
Total Nitrogen (mg L-1) |
|
1.23 (0.96
– 1.54) |
1.22 (0.98
– 1.58) |
1.21 (0.93
– 1.52) |
Ortho-phosphate Phosphorus (mg L-1) |
|
0.05 (0.02
– 0.08) |
0.05 (0.01
– 0.08) |
0.05 (0.02
– 0.07) |
Total Phosphorus (mg L-1) |
|
0.09 (0.07
– 0.11) |
0.09 (0.06
– 0.12) |
0.09 (0.07
– 0.11) |
Silica (as SiO2) (mg L-1) |
|
1.0 (0.4
– 1.5) |
1.0 (0.5
- 1.6) |
1.0 (0.6
– 1.7) |
Chlorophyll-a (mg L-1) |
|
4.8 (0.9
– 19.1) |
4.7 (0.6
– 21.7) |
4.9 (0.6
– 24.0) |
Phaeo-pigment (mg L-1) |
|
1.6 (0.2
– 7.1) |
1.5 (0.2
– 5.6) |
1.8 (0.2
– 7.5) |
E. coli. (cfu
per 100 mL) |
|
8400 (910
– 82000) |
7200 (570
– 33000) |
5100 (1400
– 12000) |
Faecal Coliforms (cfu per 100 mL) |
|
29000 (3300
– 120000) |
29000 (2000
- 74000) |
12000 (3700
– 30000) |
Notes:
1.
Data presented are depth-averaged data, unless
specified otherwise.
2.
Data presented are annual arithmetic means except for
E. coli. and faecal coliform data
which are geometric means.
3.
Data enclosed in brackets indicate the ranges.
5.3.4 The level of pollutant loading to the Victoria Harbour is expected to
decrease in the future with the progressive implementation of the various
government pollution abatement measures including the Stage I of the Strategic
Sewage Disposal Scheme (SSDS) and the Central, Western and Wanchai West
Sewerage Scheme. In addition, with the
increased enforcement exerted over industrial effluents to comply with the TM,
the pollutant loading is also expected to be reduced in the future.
5.4
Water Sensitive Receivers
5.4.1 In order to evaluate water quality impacts resulting from the CWB &
IECL, the proximity of Water Sensitive Receivers (WSRs) to the CWB & IECL
site must be considered. These have
been identified below in accordance with Annex 14 of the EIAO-TM:
·
The
Victoria Harbour, which will be the receiving water body during the
construction and operation of the works.
·
A
number of reprovisioned intakes along the waterfront at Central, Wan Chai and
Causeway for the WSD salt water pumping stations and cooling water pumping
stations. Direct construction effluent
discharge with high SS could impact upon these WSRs, causing problems such as
blocked filters and wear on equipment.
Other intakes of WSD salt water pumping stations are too far to be
impacted by the proposed Project.
5.4.2 There are no marine biological sensitive receivers such as mariculture
zones, commercial fisheries, or shell fisheries within the vicinity of the
construction site.
5.5
Assessment Methodology
5.5.1 The assessment of the potential impact of land-based construction
activities on water quality has been undertaken in a qualitative manner. Consideration has been given to controlling
potentially harmful impacts from site works and to the use of ‘best’ practice
measures to minimise the potential for discharges of pollutants to the nearby
waters of the Victoria Harbour. The
assessment of potential water pollution impacts of this Project has involved
the following tasks:
·
identifying water sensitive receivers in the
vicinity of this Project;
·
defining type and extent of construction and
operational activities with the potential to affect water quality;
·
identifying specific locations of those
construction activities;
·
assessing the potential impacts arising from
the construction activities and operation of the Project; and
·
recommending mitigation measures for minimising
any identified adverse impacts on water quality associated with the Project.
5.6
Identification of Environmental Impacts
5.6.1 In view of present infrastructure construction programmes within the
vicinity of the proposed CWB & IECL, all required reclamation will have
been completed prior to the commencement of the CWB & IECL, and no
reclamation-derived water quality impacts will occur. In addition, the boxed-tunnel portions of the CWB route will have
been constructed as part of the CRIII and WDII reclamation contracts. Potential sources of water quality impacts
arising from the construction of CWB & IECL will therefore be similar to
those of other general land-based construction activities and include :
·
construction run-off and drainage;
·
sewage
effluent produced by the on-site workforce;
·
general
construction activities;
·
diversion
of existing watercourses or drainage; and
·
groundwater
discharge during sub-surface excavation.
5.6.2
It is expected that the excavation activities
during tunnelling will not remove the marine sediment that is left in situ during WDII reclamation. However, about 730 m3 of marine
sediment will be excavated during the construction of the pier foundations for
the elevated section of IECL at the Causeway Bay Typhoon Shelter. Section 6.5.17 provides further discussion
on the quality of the excavated marine sediment, and Sections 6.6.11 and 6.7.9
present the appropriate handling and disposal methods of the excavated marine
sediment.
5.6.3 It is considered that impacts resulting from the operation of CWB &
IECL, in terms of water quality, will be minimal and similar for both the
elevated and tunnel sections of the route.
Surface runoff from slip-roads and elevated structures may be
contaminated by oils leaked from passing vehicles, and tunnel seepage would
potentially be contaminated to the same extent. It is considered that impacts upon water quality will be minimal
provided that the tunnel and elevated sections of the CWB & IECL are
designed with adequate drainage systems and appropriate oil interceptors, as
required.
5.7
Prediction and Evaluation of Environmental Impacts
5.7.1 Run-off and drainage from construction sites may contain increased loads
of sediments, other SS and contaminants.
Potential sources of pollution from site drainage include:
·
run-off
and erosion from site surfaces, drainage channels, earth working and excavated
spoil stockpiles;
·
bentonite
slurries and other grouting materials;
·
concrete
batching plant washout and drainage from dust suppression sprays; and
·
fuel,
oil and lubricants from construction vehicles and equipment.
5.7.2
Of concern for the CWB & IECL are the
potential physical impacts upon the flushing and cooling water intakes along
the waterfront of Central, Wan Chai and Causeway Bay, caused by increased SS
concentrations in the Victoria Harbour as a result of any direct discharge of
construction runoff. These impacts may
include operational difficulties caused by blocked filters and wear of pump
components. Potential impacts upon
culverts and drainage systems in the vicinity of the works are another key
concern, as material accumulation within drains and culverts can make areas
highly susceptible to flooding. Any
increase in SS from the site could exacerbate the problem, leading to
siltation, blocked channels, and associated flooding when heavy rainfall
occurs.
5.7.3
On-going site construction activities will have
the potential to cause water pollution from debris and rubbish, such as
packaging and used construction materials, which reduce the aesthetic quality
of the water body. In addition,
spillage of liquids such as oil, diesel and solvents are likely to affect water
quality if they enter surrounding water bodies.
5.7.4 Sewage effluents arising from the on-site construction workforce also
have the potential to cause water pollution.
In general, sewerage effluents should be discharged to the public
sewerage system near the works site. If
there are only a relatively small number of workers, appropriate disposal
facilities in the form of chemical toilets should be adequate. TM standards should be applied to any sewage
effluent discharges.
5.7.5 The extent of water quality impact associated with the works will mainly
be dependent upon construction methods and the distance from the sensitive
receivers. The anticipated impacts
associated with potential construction activities are outlined below:
5.7.6 The majority of the CWB will comprise underground tunnel, the
construction of which is entrusted to TDD as part of the CRIII and WDII
reclamation contracts. However, some of
the CWB route will comprise slip roads linking the tunnel portion to existing
infrastructure. Impacts resulting from
construction activities associated with these slip-roads will include generic
impacts outlined above, in particular those resulting from runoff, debris
entering the Victoria Harbour and sewage effluent disposal. However, it is considered that these impacts
could be effectively controlled through application of appropriate mitigation
measures as defined in Section 5.8.
Thus, adverse water quality impact is not predicted.
5.7.7 The IECL will be in the form of elevated road. Most of the construction activities will take place above
ground. Hence, construction runoff
would be the primary concern.
Construction activities associated with these elevated structures could
therefore lead to those generic water quality impacts outlined above, if runoff
were allowed to enter the receiving water body of the Victoria Harbour. Appropriate mitigation, as detailed in
Section 5.8, will therefore be required to prevent water quality impacts
associated with the works.
5.7.8 As described in Section 2, a small section of tunnel approximately 100 m
long will be constructed at the western portal. This tunnelling method results in an open construction site that
is exposed to the elements including rain for the majority of the construction
period. This could, therefore, lead to
construction runoff containing high concentrations of SS, which may result in
those physical water quality impacts discussed above. These could include sediment deposition within the site drainage
channels and increased concentrations of SS in the Victoria Harbour, and
associated impacts upon cooling water intakes.
However, the area of site will be comparatively small and is, therefore,
considered to be readily controllable in terms of appropriate collection and
drainage. These water quality impacts
could be effectively controlled through implementation of the mitigation
measures defined in Section 5.8.
5.7.9 For the tunnelling construction works entrusted to TDD’s CRIII and WDII
contracts, the construction method employed is expected to be diaphragm wall
method top-down construction. This
method will also lead to construction runoff containing high concentrations of
SS, which may result in those physical water quality impacts discussed
above. However, it is considered that
these water quality impacts could be effectively controlled through the
implementation of water pollution control measures, which would be addressed in
the EIA studies for CRIII and WDII.
5.7.10 Construction of the CWB & IECL will generate volumes of excavated
material requiring re-handling and disposal.
Runoff and associated water quality impacts could result from storage or
stockpiling of this material, which may require mitigation. However, it is considered that these
potential impacts should be adequately reduced through mitigation, as detailed
in Section 6.
5.8
Mitigation of Adverse Environmental Impacts
Construction Phase
5.8.1 As detailed above, construction of the CWB & IECL will have the
potential to impact upon water sensitive receivers and water quality in the
Victoria Harbour, and will therefore require appropriate mitigation. Proper site management is essential to
minimise polluted discharges and site run-off.
In addition, adequate waste disposal facilities (as discussed in Section
6) should be provided which should be used appropriately to ensure that debris
and rubbish cannot gain access to the Victoria Harbour and nearby drainage
channels. Additional water quality
mitigation measures required during the CWB & IECL construction are
detailed below and should be incorporated into the contract specifications.
5.8.2 All site construction runoff and wastewater produced from construction
activities shall be controlled and treated to prevent high levels of
contaminants entering surrounding waters and for compliance with the WPCO. The site practices outlined in ProPECC PN
1/94 “Construction Site Drainage” shall be followed as far as practicable in
order to minimise surface runoff and the chance of erosion, and also to retain
and reduce any SS prior to discharge.
·
Temporary
ditches shall be provided to facilitate runoff discharge into the appropriate
watercourses, via sedimentation traps / silt retention ponds.
·
Permanent
drainage channels shall also incorporate sediment basins or traps, and baffles
to enhance deposition rates.
·
Sand /
silt removal facilities such as sand traps, silt traps and sediment basins shall
be provided to remove sand / silt particles from run-off. These facilities shall be regularly cleaned
and maintained by the contractor. The
design of silt removal facilities shall be based on the guidelines in Appendix
A1 of ProPECC PN 1/94.
·
Collection
of spent bentonite / other grouts in a separate slurry collection system for
either cleaning and reuse / disposal to landfill shall be implemented.
·
Maintenance
and plant areas shall be bunded and constructed on a hard standing with the
provision of sediment traps and petrol interceptors.
·
All
drainage facilities must be adequate for the controlled release of storm flows.
·
Careful
programming of the works to minimise surface excavation works during the rainy
season.
·
Exposed
soil areas shall be minimised to reduce the potential for increased siltation
and contamination of runoff.
·
All
fuel tanks and storage areas shall be contained (bunded) such that spills are
not allowed to gain access to water bodies.
·
Open
drainage channels and culverts adjacent to the site shall be kept safe and free
from any debris and excavated materials arising from the works.
·
Open
stockpiles of construction materials (for examples, aggregates, sand and fill
material) of more than 50 m3 shall be covered with tarpaulin or similar
fabric during rainstorms.
5.8.3 Precautions to be taken at any time of year when rainstorms are likely,
actions to be taken when a rainstorm is imminent or forecast, and actions to be
taken during or after rainstorms are summarised in Appendix A2 of ProPECC PN
1/94. Any effluent discharged from the
site shall be diverted away from any area of embayed water.
5.8.4
In
order to maintain water quality in acceptable conditions with regard to
aesthetic quality, contractors shall be required, under conditions of contract,
to ensure that site management is optimised and that disposal of any solid
materials, litter or wastes to marine waters does not occur. Where necessary, entrapment boom shall be
provided to avoid loss of floating refuse from the construction site.
5.8.5
All fuel tanks and store areas shall be
provided with locks and be sited on sealed areas, within bunds of a capacity
equal to 110% of the storage capacity.
All maintenance and plant areas and chemical storage facilities shall be
provided with cover as far as practicable to avoid ingress of rainwater.
5.8.6
Temporary sanitary facilities, such as portable
chemical toilets, shall be provided on-site by a licensed contractor. A licensed contractor would be responsible
for appropriate disposal and maintenance of these facilities.
Operational Phase
5.8.7
A surface water drainage system would be
provided to collect road runoff. The
following operation stage mitigation measures are recommended to ensure road
runoff would comply with the TM under the WPCO:
·
The drainage from tunnel sections shall be
directed through petrol interceptors to remove oil and grease before being
discharged to the nearby foul water manholes.
·
Petrol interceptors shall be regularly cleaned
and maintained in good working condition.
·
Oily contents of the petrol interceptors shall
be properly handled and disposed of, in compliance with the requirements of the
Waste Disposal Ordinance.
· Sewage arising from ancillary facilities of CWB & IECL (for examples, car park, control room, ventilation and administration buildings and tunnel portals) shall be connected to public sewerage system. Sufficient capacity in public sewerage shall be made available to the proposed facilities.
· Road drainage should also be provided with adequately designed silt trap to minimize discharge of silty runoff.
5.8.8
The design of the operational stage mitigation
measures shall take into account the guidelines published in ProPECC PN 5/93
“Drainage Plans subject to Comment by the EPD.” All operational discharges from
the CWB into drainage or sewerage systems are required to be licensed by EPD
under the WPCO.
5.9
Evaluation of Residual Impacts
5.9.1 With the adoption and incorporation of the above recommended mitigation
measures for both construction and operation phases, no unacceptable residual
impacts on water quality are anticipated.
5.10
Environmental Monitoring and Audit
5.10.1 The potential water quality impacts arising from the proposed land-based
construction works for the CWB & IECL have been assessed. It is predicted that there will not be any
insurmountable adverse impacts on marine water quality. With the implementation of the recommended
mitigation measures, it is anticipated that the identified water quality
impacts would be kept to within acceptable levels. Monitoring of marine water quality during the construction phase
is therefore not considered necessary for this site.
5.10.2 Regular site audit shall be
carried out during construction stage to ensure that no adverse impact on the
marine waters and seawater intakes in the vicinity; and to scrutinize timely
implementation of the recommended mitigating measures.
5.11
Conclusion
5.11.1 As no reclamation will be undertaken directly for the CWB & IECL,
the primary concern with regard to water quality will be the control of runoff
during construction. This could
potentially contain elevated concentrations of SS, and could impact upon the
flushing and cooling water intakes located along the Victoria Harbour
waterfront, identified as potential sensitive receivers. However, the potential water quality impacts
could be controlled to comply with the WPCO standards by implementing the
recommended mitigation measures. No
unacceptable residual water quality impact is anticipated during construction.
5.11.2 Mitigation measures with
adequate maintenance are also recommended to remove oil and grease from the
road runoff during operation. No
unacceptable residual water quality is expected.
([1]) Marine Water Quality in Hong Kong in
1998. Results for 1998 from the Marine
Monitoring Programme of the Environmental Protection Department.