4.1
The EIA Report predicted that the discharge of treated
effluent from the normal operation of the Project would not have adverse impact
on the marine water quality. A post project monitoring (PPM) programme will be
implemented to confirm the water quality impacts predicted under normal
operation of the Project. It
should be noted that effluent quality, including the levels of E. coli, suspended solids, 5-day
biochemical oxygen demand and total residual chlorine (TRC), from the SCISTW
will also be governed by the discharge licence conditions after the Project is
commissioned.
4.2
Marine water quality monitoring is also recommended during
and after the following situations:
l
Emergency discharge as a result of equipment / power failure
at SCISTW during the operational phase;
l
Temporary sewage bypass (required for the construction of
the interconnection between the two main pumping stations at SCISTW and other
modification works) during the construction phase or early commissioning of the
Project; and
l
Emergency discharge of undisinfected effluent from SCISTW in
the event of chlorination / dechlorination plant failure during the operational
phase.
4.3
A framework of the responses has been formulated in this
EM&A Manual to minimize the impacts from the temporary sewage bypass and emergency
discharge. Detailed contingency plan and
operational procedures for the Project will be developed separately at the
detailed design stage.
4.4
In this section, the requirements, methodology, equipment,
monitoring locations, criteria and protocols for the monitoring and audit of water
quality impacts during the construction and operation phase of the Project are
presented.
4.5
A post project monitoring (PPM) programme will be
implemented to confirm the water quality impacts predicted under normal
operation of the Project. The PPM would consist of one-year baseline
monitoring before commissioning and at least one-year impact monitoring after
commissioning of the Project. The extent of PPM programme is subject to the
prevailing environmental conditions at the time before commissioning of the
Project. The PPM after the first year of
operation of the Project will be subject to the first year review. The PPM shall comprise (i) effluent quality
monitoring, (ii) marine water quality monitoring, (iii) ecotoxicological
assessment, (iv) sediment quality monitoring, (v) benthic survey assessment and
(iv) water quality and plume dispersion modelling and assessment. Details of
the PPM requirements shall be agreed with the Director of Environmental
Protection prior to the commissioning of the Project. Based on the PPM results, recommendation
shall be made with respect to the need for improvement to the operation of the
Project as well as the requirements for, and methodologies to be employed in
the course of, future monitoring programme or supplementary investigations to
quantitatively assess and predict future performance of the Project and its
impact on the environment. A Post
Project Monitoring and Audit Manual shall be prepared for long term monitoring of
the performance or the outfall to ensure acceptability of the impacts of the effluent
discharges on the receiving environment.
Effluent
and Marine Water Quality Monitoring
Effluent Monitoring
4.6
The effluent monitoring data (TRC, chlorination by-products
(CBPs), arsenic, chromium, copper, mercury, nickel, zinc, sulphide,
surfactants, phenol, cyanide and ammonia nitrogen (NH3-N), E.coli, suspended solids (SS), 5-day
biochemical oxygen demand (BOD5), total kjeldahl
nitrogen (TKN), total phosphorus (TP), ortho-phosphate (PO4)
and other contaminant of concern (COC) to be agreed with EPD) shall be used to
provide information to investigate the observations in the marine water quality
monitoring and whole effluent toxicity test (WETT).
Effluent Sample
Collection
4.7
Effluent from SCISTW shall be collected at a suitable
location. The sampling location should
be agreed with the Environmental Consultant, approved by DSD and EPD, and
should fulfil the following requirements:
l
Effluent collected
at the sampling location is representative to the effluent discharged at the
effluent diffuser
l
Sampling works at
the sampling location would not interfere with the SCISTW operation
l
Sampling works at the sampling location
would not induce safety hazard (e.g. staff sampling effluent drops into the
culvert)
4.8
The effluent should
be collected in a full 24-hour period. Twenty
four-hour flow-weighted composite effluent sample for subsequent chemical analysis
and testing[1] should be prepared by the
following procedures:
l
Collect effluent
sub-sample at bi-hourly interval over a 24 hour period
l
Obtain flow record of
SCISTW for the 24-hour sampling period
l
Calculate the volume
of each sub-sample for preparation of flow-weighted composite sample
l
Transfer the
appropriate volume of sub-samples to a clean container and mix thoroughly
4.9
The effluent sampling
should be planned carefully to ensure appropriate volume of effluent
sub-samples is collected to prepare sufficient amount of flow-weighted
composite effluent sample for carrying out subsequent chemical analysis and
testing.
Effluent
Monitoring Schedule
4.10
The effluent monitoring shall be performed over one year
before commissioning of the Project and the first year of Project operation and
shall be coincide with the marine water sampling schedule as detailed in
Sections 4.25 and 4.26. The
effluent monitoring shall be ceased in the events of any emergency discharges.
4.11
Besides, a close to real time on-line operation
phase monitoring on TRC in treated effluent shall be performed daily over the
first year of Project operation after the commissioning period of the Project.
4.12
The effluent concentrations for nine CBPs
(bromoform, bromodichloromethane, chloroform, dibromochloromethane, bromoacetic
acid, chloroacetic acid, dibromoacetic acid, dibromoacetic acid, dibromoacetic
acid), arsenic,
chromium, copper, mercury, nickel, zinc, sulphide, surfactants, phenol,
cyanide, TRC, E.coli, SS, BOD5,
TKN, NH3-N, TP and PO4 shall
be determined by laboratory. The suggested
analysis method and detection limit are presented in Table 4.6.
4.13
Nine CBPs species are
selected for monitoring because:
l
they are known to be
the most important and abundant CBPs, relatively more toxic and of greater
concern, and therefore serve as good indicators for CBPs;
l
international
drinking water standards for these 9 CBPs are made available for protection of
public health;
l
they were classified
as contaminants of concern (COCs) in the HATS ADF EIA, and found to be of
concentrations higher than other halogenated organics in the
chlorinated/dechlorinated (C/D) HATS effluent;
l
for other 25
halogenated organics grouped as “potential CBPs” and studied in the ADF EIA,
they are not considered in setting the discharge limits because almost none of
them were found in the C/D HATS effluent.
Moreover, most of these compounds are not directly related to the
disinfection process, but they were included in the EIA study merely for
conservative assessment as some of them are regulated by US for controlling
industrial discharges.
4.14
The TRC discharge standards for the
effluent are recommended based on the water quality modelling results. Besides, CBPs discharge limit is set with
reference to the Toxicity Reference Value (TRVs) used in the ecological risk
assessment under the EIA. The TRVs for
the CBPs species are either the most stringent international water quality
criteria (for such species), or values specifically derived from relevant
ecotoxicity of the highest toxicity using the USEPA procedures. Effluent reaching the zone of initial
dilution (ZID) is assumed to have diluted to 38 times which is the minimum
dilution predicted for the Stage 2A. The
limits are set such that all proposed TRVs should be met at the edge of ZID.
4.15
The discharge limits derived according to
the above approach are shown below:
Table
4.1 Discharge Limits for TRC
and CBPs
|
Determinant |
Toxicity Reference Values (mg/L) |
Discharge Limit (measured in HATS
effluent) (mg/L) |
|
|
Total
residual chlorine |
0.013
(edge of ZID) 0.008
(edge of mixing zone) |
0.2
(95 %tile) 0.4
(Max.) |
|
|
Bromoform |
Tri- halomethanes (THMs) |
0.36 |
13 |
|
Bromodichloromethane |
0.022 |
0.8 |
|
|
Chloroform |
0.012 |
0.45 |
|
|
Dibromochloromethane |
0.034 |
1.2 |
|
|
Bromoacetic
acid |
Halo-acetic Acids (HAAs) |
1.6 |
60 |
|
Chloroacetic
acid |
32 |
1200 |
|
|
Dibromoacetic
acid |
0.69 |
26 |
|
|
Dichloroacetic
acid |
0.23 |
8 |
|
|
Trichloroacetic
acid |
93 |
3500 |
|
l
The suggested
detection limit was in light of the concentration of interest (COI) for human
health and/or ecological resources, which was based on local/international
authority approved standard.
Determinant at concentration below COI is not expected to induce concern
to human health and ecological resources.
4.16
The discharge
license of the existing SCISTW, E coli level
and quality of other relevant parameter of the effluent discharge into the
inlet of the submarine outfall are listed below:
l
E coli (no. per
100 ml): 20,000 (Geometric Mean), 300,000 (95 Percentile)
l
pH: 6-10
l
Suspended Solids:
55 mg/L (Percentile Standards)
l
Biochemical Oxygen
Demand (5 days, 20oC): 75 mg/L (Percentile Standards)
4.17
The Environmental Consultant shall collect from SCISTW the
chemical dosage record of the chlorination/dechlorination process under the
Project for the first year operation after the commissioning period of the
Project for data analysis. The
Environmental Consultant shall compare the actual dosages with those predicted under
the EIA Study to see whether there is any significant difference which causes
deviations of the monitoring results from the model prediction under the EIA
Study. The close to real time on-line monitoring (on dosage of sodium
hypochlorite and sodium bisulphite) record and review shall be submitted to DSD
and EPD.
Marine Water Quality Monitoring and Locations
4.18
The marine water quality monitoring (for CBPs, TRC, unionized
ammonia (UIA), arsenic, chromium, copper, mercury, nickel, zinc, sulphide,
surfactants, phenol, cyanide, E.coli,
SS, BOD5, ammonia nitrogen (NH3-N), nitrite nitrogen (NO2),
nitrate nitrogen (NO3), TP, PO4 and other COC to be
agreed with EPD) is recommended in order to achieve the following objectives:
l
To check whether the Project would cause an increase in
concentrations of these contaminants in marine water close to the SCISTW
outfall diffuser.
l
To verify the predictions of the Human Health Risk Assessment,
details on the use of monitoring data for this objective are presented in Section 5 of the EM&A Manual.
l
To verify the predictions of the Ecological Risk Assessment,
details on the use of monitoring data for this objective are presented in Section 6 of the EM&A Manual.
4.19
It is recommended to set up 6 near field
monitoring stations with their locations and co-ordinates as shown in Figure 4.1,
which also shows the boundary of the ZID and the boundary of mixing zone. The
ZID was determined by the near field water quality modelling. The mixing zone provided in Figure 4.1
was based on the far field water quality model results predicted for UIA at the
early phase of Stage 2A in 2014. As
shown in Figure
4.1, 4 stations would be located at the edge of ZID (stations 2 and 3)
and the edge of mixing zone (stations 1 and 4), forming a transect line
perpendicular to the effluent diffuser.
Stations SM6 and SM12 would be located in areas that would unlikely be
affected by the Project and will therefore serve as control stations. The coordinates of the proposed monitoring
stations are listed in Table 4.2.
Table 4.2 Proposed
Marine Water Quality Monitoring Stations Close to SCISTW Outfall
|
Station |
Description |
Easting |
Northing |
|
1 |
Edge of Mixing
Zone (northwest of effluent diffuser) |
829762.00 |
819604.47 |
|
2 |
Edge of ZID (northwest of effluent diffuser) |
830117.99 |
819251.93 |
|
3 |
Edge of ZID (southeast of effluent diffuser) |
830186.21 |
819184.37 |
|
4 |
Edge of Mixing Zone (southeast of effluent diffuser) |
830525.00 |
818848.87 |
|
SM6 |
Control Station |
826179.81 |
805902.89 |
|
SM12 |
Control Station |
819524.19 |
808420.40 |
4.20
The Environmental
Consultant shall review and analyze the concentrations for E.coli, SS, BOD5, NH3-N,
UIA, NO2, NO3, PO4, TP, arsenic, chromium, copper, mercury, nickel, zinc, sulphide,
surfactants, phenol, cyanide and other COC to be agreed with EPD in the Western
Buffer, Victoria Harbour and Southern waters (including the semi-enclosed bays
as identified in the EIA) during the one year before the commissioning of the
Project and the first year of Project operation.
4.21
The Environmental
Consultant shall also review and analyze the E.coli concentrations collected at the beaches in Tsuen Wan
District during the one year before the commissioning of the Project and the
first year of Project operation.
4.22
It is recommended to set up 21 far field
monitoring stations as shown in Figure 4.2.
These stations represent the areas which would potentially have water
quality improvement due to the Project implementation as predicted by the water
quality model.
4.23
The coordinates of the proposed monitoring
stations are listed in Table 4.3.
Table
4.3 Proposed Marine Water Quality
Monitoring Stations in the Far Field Area
|
Station |
Description |
Easting |
Northing |
Parameters |
|
B7 |
Anglers’ Beach |
823836.36 |
825044.52 |
E.coli |
|
B8 |
|
825215.29 |
824933.71 |
|
|
B9 |
Ho Mei Wan Beach |
825388.98 |
825067.17 |
|
|
B10 |
|
825731.46 |
825330.90 |
|
|
B11 |
|
825917.78 |
825385.83 |
|
|
B12 |
|
826277.40 |
825519.01 |
|
|
B13 |
|
827237.94 |
825301.02 |
|
|
B14 |
Ma Wan Beach |
824431.47 |
823415.85 |
|
|
WM2 |
Western Buffer |
827881.70 |
816189.04 |
E.coli, SS,
BOD5, NH3-N, UIA, NO2, NO3, PO4, a suite of heavy metals, sulphide, surfactants, phenol, cyanide and other COC to
be agreed with EPD |
|
WM3 |
Western Buffer |
828048.67 |
820118.17 |
|
|
WM4 |
Western Buffer |
825354.99 |
823325.61 |
|
|
VM5 |
|
836091.75 |
816541.13 |
|
|
VM7 |
|
832495.44 |
817473.60 |
|
|
NM1 |
North Western |
820255.99 |
823213.76 |
|
|
SM3 |
East Lamma Channel |
833462.67 |
809640.82 |
|
|
SM9 |
West Lamma Channel |
824950.63 |
814983.89 |
|
|
SM6 |
West Lamma Channel |
826179.81 |
805902.89 |
|
|
SM4 |
Semi-enclosed Bay – |
832319.64 |
808221.84 |
|
|
SM10 |
Semi-enclosed Bay – |
821337.85 |
818133.63 |
|
|
SM11 |
Semi-enclosed Bay – |
819888.34 |
813185.26 |
|
|
SM13 |
Semi-enclosed Bay – |
814119.93 |
808604.29 |
4.24
During each beach monitoring event, beach water samples shall
be collected where the water depth is between thigh to waist depth i.e. about 1
metre depth for analysis of E. coli bacteria and physical measurements
of pH, salinity and turbidity.
4.25
For all other marine water monitoring
stations, sampling shall be taken at three water depths, namely, 1m below water
surface, mid-depth and 1m above sea bed, except where the water depth is less
than 6m, in which case the mid-depth station may be omitted. Shall the water depth be less than 3m, only
the mid-depth station will be monitored.
At each monitoring station, six replicate samples shall be collected at
each water depth, which is a reasonable number of replicates for environmental
monitoring data to be analyzed by common statistical analysis method (Townend,
2002). The Environmental Consultant
shall review the number of replicates by statistical power analysis after the
first set of baseline marine water quality monitoring. Sufficient volume of
each water sample shall be collected for analysis to achieve the required
detection limit. In-situ measurements at DO,
pH, salinity, temperature and turbidity shall be taken at 0.5m depth intervals
at all the marine water quality monitoring stations.
4.26
The marine water quality monitoring shall be performed over
one year before commissioning of the Project and the first year of Project
operation. For baseline monitoring, marine water sampling shall coincide with
the baseline effluent sampling. At least 4 survey events shall be undertaken over
one year to give adequate coverage of different tidal states during both wet
and dry seasons. During each survey event, sampling shall be taken at 2
slack tide conditions (low-water and high-water). The purpose of the baseline
monitoring is to establish ambient conditions without the Project. The baseline monitoring shall be ceased in
the events of any emergency discharges.
4.27
Similarly, the marine water sampling for operation phase
monitoring shall coincide with the effluent sampling for operation phase
monitoring. At least 4 operational phase survey events shall be undertaken over
one year to give adequate coverage of different tidal states during both wet
and dry seasons. During each survey event, sampling shall be taken at 2
slack tide conditions (low-water and high-water). The operation phase
monitoring shall be ceased in the events of any emergency discharges and the monitoring programme after
the first year of operation of the Project will be subject to the first year
review.
4.28
Besides, a close to real time on-line
operation phase monitoring on TRC in marine water shall be performed daily over
the first year of Project operation after the commissioning period of the
Project. Monitoring programme after the first
year of operation of the Project will also be subject to the first year review.
Laboratory Measurement / Analysis
4.29
The suggested analysis method and detection
limit are presented in Table 4.6.
Statistical Analysis of Monitoring Data
4.30
After the data of the first set of baseline marine water
quality monitoring has been obtained, a statistical power analysis shall be
conducted to verify and review the number of replicates required for subsequent
baseline and operation phase monitoring sessions.
4.31
The monitoring data should be analyzed
using analysis of variance techniques to test for differences between sampling
locations.
Once a time series of data (sequential sampling events) has been
gathered, difference should be tested between the stations and between the
different sampling events to examine any temporal trends in pollutant
concentrations in marine water. The
statistical analysis of monitoring data would provide information to identify
any difference of pollutant level in marine water in spatial and temporal
terms.
4.32
One key objective of the proposed monitoring programme is to
check whether the Project would cause an increase in contaminant concentrations
in marine water close to the SCISTW outfall (such as for CBPs, TRC, UIA,
arsenic, chromium, copper, mercury, nickel, zinc, sulphide, surfactants,
phenol, cyanide). Therefore, once the operation phase
monitoring programme for the year is complete, the operation phase monitoring
data obtained for the year should be compared with the baseline monitoring data
using statistical analysis technique to determine whether there is increase of contaminant
concentrations in marine water after implementation of the Project. Should the statistical analysis reveal that contaminant
concentrations in marine water increase after implementation of the Project,
the monitoring data collected in effluent quality monitoring shall be used to
provide information to investigate whether such increase is due to the effluent
discharged by the Project.
4.33
If any of the near field water quality
criteria as indicated in Table 4.3a are
exceeded, the follow-up actions as listed below shall be taken:
l
Check the accuracy of
the measurements and the correctness of the analytical results
l
Increase the
monitoring frequency to check if exceedance persists
l
In case of persistent
CBP exceedances:
Ø monitor
the CBPs levels in the influent, and in the effluent stream before and after
chlorination / dechlorination
Ø review
the chemical dosages and TRC levels in the effluent
Ø Consider
measures (e.g. adjusting chemical dosages) to reduce TRC and CBPs levels in the
effluent. Such measures should not cause
significant deterioration in the required disinfection power or targeted
bacteria reduction level
l
Conduct human health risk assessment and ecological risk
assessment using the operation phase monitoring data obtained for the year to
verify that the human health risk/impact and ecological risk due to potential contaminants
discharged from SCISTW effluent is acceptable.
The details of the human health risk assessment and ecological risk
assessment are presented in Section 5 and
Section 6 of the EM&A Manual
respectively.
Table 4.3a Near Field Water Quality Criteria
|
Parameter |
Value |
Type
/ Period |
Applicable
Zones / Uses |
|
Unionized ammonia (UIA) |
≤ 0.021 mg/l (as N) (2) |
Annual average |
At edge of ZID (1) |
|
≤ 0.035 mg/l (as NH3)
(3) |
4-day average |
At edge of ZID (1) |
|
|
≤ 0.233 mg/l (as NH3)
(3) |
1-hour average |
At edge of ZID (1) |
|
|
pH |
6.5 – 8.5, and change ≤ 0.2 |
≥ 90% of occasions |
At edge of ZID (1) |
|
Temperature |
change ≤ 2 oC |
≥ 90% of occasions |
At edge of ZID (1) |
|
Sulphide |
≤ 0.02 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Cyanide |
≤ 0.005 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Total residual chlorine (TRC) |
≤ 0.013 mg/l |
Daily Maximum |
At edge of ZID (1) |
|
Surfactants |
≤ 0.03 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Copper |
≤ 0.005 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Nickel |
≤ 0.005 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Total chromium |
≤ 0.05 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Zinc |
≤ 0.02 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Mercury |
≤ 0.00021 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Arsenic |
≤ 0.02 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Phenol |
≤ 0.005 mg/l |
≥ 90% of occasions |
At edge of ZID (1) |
|
Acute
Toxicity |
0.3 acute toxicity units (TUa)
(derived from LC50 values based on whole effluent toxicity tests) (4) |
One hour average condition not to
exceed this value |
At
edge of ZID (1) |
(Source: EEFS Report on Community Consultation for the
Proposed Water Quality Criteria)
(1) For a surface plume, initial dilution is
defined as the dilution obtained at the centre line of the plume when the
sewage reaches the surface. For a
trapped plume, initial dilution is defined as the dilution obtained at the
center line of the plume where the plume reaches the maximum rise height when
the vertical momentum / buoyancy of the plume becomes zero.
(2) The WQC for
annual averaged UIA was derived with reference to the WQO under WPCO which is
expressed as N.
(3) The WQC for
1-hour and 4-day averaged UIA was derived with reference to the USEPA which is
expressed as NH3.
(4) USEPA
Technical Support Document for Water Quality-Based Toxics Control (March 1991),
from which one acute Toxicity Unit (TUa) is defined as TUa = 100/LC50, where
LC50 = % of effluent which gives 50% survival of the most sensitive of the
range of species tested.
4.34
Based on the review
and analysis of the monitoring data, the Environmental Consultant shall also
review the effectiveness of the Project for improving the water quality in the
marine water (in terms of E.coli, SS, BOD5, TIN, UIA and PO4 etc.) in the Western Buffer,
Ecotoxicological
Assessment (Indicative)
4.35
A programme of
ecotoxicological assessment shall be proposed, with full scientific
justification, for the approval of the EPD to determine the toxicity of the
treated effluent and the toxicity of the receiving marine water. All ecotoxicological samples shall be fully
characterized physically and chemically. The list of determinants shall include
ammonia, sulphide, a suit of heavy metal, selected species of CBPs, TRC and
other COC to be agreed with EPD. The test organisms used for the toxicity tests
shall include representative species of the local environment, preferably
including common species of fish cultured locally. Drainage Services Department
(DSD) is required to undertake routine sampling and testing for
characterization of the treated effluent under the Water Pollution Control
Ordinance discharge licence for SCISTW. The Environmental Consultant shall
coordinate the works required under effluent monitoring and liaise with DSD
properly in order to minimize duplication of effort and expenditure for
sampling and testing related to this Assignment. The requirements of ecotoxicological
assessment are detailed in Section 6
of this EM&A Manual.
Sediment Quality
Monitoring (Indicative)
4.36
Sediment sampling shall be performed four times over the field work period of
one year to give adequate coverage of both wet and dry seasons. The sampling
locations shall cover selected stations in both near-field and far-field and
analysis of sediment samples to be conducted shall be agreed with the Director
of Environmental Protection. Analysis shall include determinands such as
percentage of silt/ clay, pH, acid volatile sulphides, total volatile solids,
total organic carbon, ammonia, total nitrogen, total phosphorous, a suite of
metals and other contaminants of concern identified in the treated effluent, if
any.
Benthic Survey
(Indicative)
4.37
Benthic sampling shall be conducted
four times over the field work period of one year, in parallel with the
sediment sampling described in Section 4.34 above, using the same monitoring
stations. The benthos collected shall be identified to the lowest taxonomic
level and the benthic community structure determined.
Water Quality and
Plume Dispersion Modelling and Assessment (Indicative)
4.38
The modellinging software shall be capable of accurately simulating
stratification and salinity transport in three dimensions within the model
area.
4.39
The modelling software shall contain hydrodynamic, water
quality and particle dispersion modules. The hydrodynamic and water quality
modules shall have proven successful applications locally and overseas.
4.40
The hydrodynamic and water quality modules shall strictly
conserve mass at all levels.
4.41
No field data collection is required for the purposes of
model calibration for this study. However, before commencement of this study,
the models shall have been properly calibrated and validated with the field
data collected from studies which may include, inter alia:
·
Hydraulic and Water Quality Studies in
·
Port and Airport Development Strategy - Enhancement of WAHMO
Mathematical Models (1990)
·
Strategic Sewage Disposal Scheme Stage II - Oceanic Outfall,
Oceanographic Surveys and Modelling (1992)
·
Update on Cumulative Water Quality and Hydrological Effect
of Coastal Developments and Upgrading of Assessment Tool (1998)
·
Environmental and Engineering Feasibility Assessment Studies
in relation to the Way Forward of the Harbour Area Treatment Scheme (2004)
·
EPD’s routine monitoring data
·
Tidal data from HK Observatory,
4.42
Tidal elevation data shall be calibrated and validated in both
frequency and time domain manner.
4.43
For the purposes of calibration and validation, the model
shall simulate not less than 15 days of real tide sequence (excluding model
spin up) in both dry and wet seasons with due consideration for the time
required to establish initial conditions.
4.44
In general, the hydrodynamic models must be calibrated to
the following criteria:
Criteria
Level of
fitness
with
field data
Ø
tidal elevation (root mean square) < 8 %
Ø
maximum phase error at High Water and Low Water <20 minutes
Ø
maximum current speed deviation < 35 %
Ø
maximum phase error at peak speed < 20 minutes
Ø
maximum direction error at peak speed < 15 degrees
Ø
maximum salinity deviation <
2.5 ppt
4.45
Model runs shall be undertaken to simulate the actual
conditions to help ascertain and predict the impact of the discharge on the
receiving waters. The water quality modelling results shall be qualitatively
explainable, and any identifiable trend and variations in water quality shall
be reproduced by the model. The water
quality model shall simulate and take account of the interaction of dissolved
oxygen, phytoplankton, organic and inorganic nitrogen, phosphorus, silicate,
biochemical oxygen demand, temperature, suspended solids, air-water exchange
processes. It shall also simulate salinity transport and E.coli dispersion. Salinity results simulated by hydrodynamic
models and water quality models shall be demonstrated to be consistent.
4.46
The hydrodynamic and water quality models shall be carefully
designed such that its boundary is remote enough and would not be affected by
the Project with a fine grid commensurate with the detail of assessment.
In general, the model grid size shall be less than 400m in open waters and less
than 75m around sensitive receivers and outfall diffusers. A fine grid
model can be used for detailed assessment but shall either be dynamically
linked to or form part of the far field model, which cover the Pearl Estuary
and the Dangan (Lema) Channel to incorporate the effects of oceanic and Pearl
River discharge processes, through nesting or gradual refinement techniques.
The model coverage and grid schematisation shall be agreed with the Director of
Environmental Protection.
4.47
Hydrodynamic and water quality models shall be run to
simulate 15 days (excluding model spin up) of real tide sequence.
4.48
The models shall be used to help ensure cost effective
design of the field monitoring programme and to help establish the extent of
and influences on the zone of influence.
4.49
The models shall be used to facilitate the assessment of the
impact of the treated effluent discharge on the receiving environment in order
to ensure that the study objectives are fully satisfied.
4.50
Dye Tracer Surveys, if necessary shall be conducted during
wet and dry seasons in post-commissioning period, both on a flood tide and an
ebb tide, to assess the behaviour of the effluent plume from the discharge
points and to quantify the actual dilution under both stratified and non-stratified
water columns.
4.51
The monitoring programme shall maintain a degree of
flexibility to allow the incorporation of the findings based on the monitoring
results obtained as the study progresses. Therefore, the location and number of
monitoring stations, number of samples and replicates, and types of tests and
analyses will be subject to continual review by the Project Proponent and
amendment as necessary. Accordingly, upon direction from the Director of
Environmental Protection, resources for the monitoring programme may be
redeployed, reduced or increased within the study area.
4.52
Field sampling and survey, if required, shall be proposed
and arranged to characterize other major background pollution discharges in the
Study Area.
4.53
The potential impacts of the treated effluent on marine
ecology including commercial and aquaculture fisheries shall be assessed based
on the water quality and ecotoxicological assessment and assessment of the
available data in respect of the water quality.
4.54
Impacts arising as a consequence of the discharge of treated
effluent from SCISTW shall be distinguished from those arising from other
pollution sources and anthropogenic activities.
Monitoring
Locations and Schedule
4.55
Marine water quality monitoring for E.coli is recommended during and after the following situations:
Case 1 - Emergency discharge as a result of equipment /
power failure at SCISTW during the operational phase;
Case 2 - Temporary sewage bypass (required for the
construction of the interconnection between the two main pumping stations at
SCISTW and the modification works at the main pumping station at SCISTW) which
will be conducted in the dry season during the construction phase or early
commissioning of the Project;
Case 3- Emergency discharge of undisinfected effluent
from SCISTW in the event of chlorination / dechlorination plant failure during
the operational phase; and
Case 4- Temporary
sewage bypass (required for the modification to the North West Kowloon Pumping
Station) which will be conducted in the dry season during the construction
phase or early commissioning of the Project;
4.56
It is recommended to set up 56 monitoring
stations (for Case 1), 42 monitoring stations (for Case 2), 17 monitoring
stations (for Case 3) and 13 monitoring stations (for Case 4) as shown in Table 4.4. Locations of the monitoring stations are
shown in Figure
4.2. These stations represent the
sensitive receivers which could potentially be affected by the temporary sewage
bypass or emergency discharge from HATS. These stations also cover some gradient
stations to assist in the identification of the source of any impact at the sensitive
receivers as well as the control station outside the influence zone of the temporary
discharge as predicted by the water quality modelling.
4.57
The coordinates of the proposed monitoring
stations are listed in Table 4.4.
Table 4.4 Proposed Marine Water Quality
Monitoring Stations for Emergency Situations
|
Station |
Description |
Easting |
Northing |
|
Case 1 - Emergency Discharge of
Screened Sewage via all the Stage 1 and Stage 2 PTWs |
|||
|
B7 |
Anglers’ Beach |
823836.36 |
825044.52 |
|
B8 |
|
825215.29 |
824933.71 |
|
B9 |
Ho Mei Wan Beach |
825388.98 |
825067.17 |
|
B10 |
|
825731.46 |
825330.90 |
|
B11 |
|
825917.78 |
825385.83 |
|
B12 |
|
826277.40 |
825519.01 |
|
B13 |
|
827237.94 |
825301.02 |
|
B14 |
Ma Wan Beach |
824431.47 |
823415.85 |
|
B24 |
Big |
843474.09 |
811730.33 |
|
B25 |
Rocky |
844030.05 |
810286.64 |
|
B26 |
Shek O Beach |
843891.17 |
809864.31 |
|
B30 |
St. Stephen’s Beach |
839990.14 |
808461.60 |
|
B31 |
|
838616.79 |
808752.43 |
|
B32 |
|
838104.70 |
809598.73 |
|
B33 |
|
838056.97 |
809993.31 |
|
B34 |
|
838008.93 |
810827.28 |
|
B35 |
|
836785.60 |
811635.55 |
|
F1 |
Tung Lung Chau Fish Culture Zone |
847571.26 |
813102.00 |
|
F4 |
Lo Tik Wan Fish Culture Zone |
831366.51 |
809221.48 |
|
F5 |
Ma Wan Fish Culture Zone |
823875.25 |
823699.48 |
|
WSD4 |
Tsuen Wan flushing water intake |
828908.71 |
825681.26 |
|
WSD5 |
Tsing Yi flushing water intake |
829862.33 |
823104.16 |
|
WSD6 |
Cheung Sha Wan flushing water intake |
833991.16 |
820235.42 |
|
WSD7 |
Kowloon South flushing water intake |
833968.78 |
818053.54 |
|
WSD9 |
Tai Wan flushing water intake |
837955.17 |
818412.01 |
|
WSD10 |
Cha Kwo Ling flushing water intake |
841379.00 |
817859.28 |
|
WSD11 |
Yau Tong flushing water intake |
842149.61 |
816974.14 |
|
WSD12 |
Tsueng Kwan O flushing water intake |
845512.14 |
817421.15 |
|
WSD13 |
Siu Sai Wan flushing water intake |
843904.21 |
814469.38 |
|
WSD15 |
Sai Wan Ho flushing water intake |
841215.41 |
816451.38 |
|
WSD17 |
|
839685.64 |
817081.46 |
|
WSD18 |
Central Water Front flushing water intake |
833935.18 |
816624.15 |
|
WSD19 |
Sheung Wan flushing water intake |
833383.13 |
816836.34 |
|
WSD20 |
|
830826.34 |
816244.46 |
|
WSD21 |
Ap Lei Chau flushing water intake |
834105.49 |
810567.95 |
|
WSD22 |
Wan Chai flushing water intake |
836246.19 |
816134.92 |
|
VM12 |
Gradient Station |
830542.34 |
821139.51 |
|
VM14 |
Gradient Station |
829254.66 |
825159.72 |
|
VM15 |
Gradient Station |
832707.02 |
818964.77 |
|
VM8 |
Gradient Station |
830363.95 |
817092.23 |
|
VM7 |
Gradient Station |
832495.44 |
817473.60 |
|
VM5 |
Gradient Station |
836091.75 |
816541.13 |
|
VM2 |
Gradient Station |
839713.80 |
817641.47 |
|
VM4 |
Gradient Station |
838056.49 |
817637.50 |
|
VM1 |
Gradient Station |
841809.43 |
816567.96 |
|
JM3 |
Gradient Station |
844931.70 |
816956.95 |
|
EM1 |
Gradient Station |
844379.62 |
815140.61 |
|
EM2 |
Gradient Station |
845472.92 |
813712.75 |
|
EM3 |
Gradient Station |
845771.79 |
810953.82 |
|
WM1 |
Gradient Station |
830685.17 |
812441.28 |
|
WM2 |
Gradient Station |
827881.70 |
816189.04 |
|
WM4 |
Gradient Station |
825354.99 |
823325.61 |
|
SM3 |
Gradient Station |
833462.67 |
809640.82 |
|
SM2 |
Gradient Station |
836402.69 |
809492.93 |
|
MM13 |
Control Station |
864290.82 |
808693.11 |
|
SM17 |
Control Station |
814115.31 |
801690.83 |
|
Case 2 – Temporary Bypass of
Screened Sewage via the Stage 1 PTWs |
|||
|
B7 |
Anglers’ Beach |
823836.36 |
825044.52 |
|
B8 |
|
825215.29 |
824933.71 |
|
B9 |
Ho Mei Wan Beach |
825388.98 |
825067.17 |
|
B10 |
|
825731.46 |
825330.90 |
|
B11 |
|
825917.78 |
825385.83 |
|
B12 |
|
826277.40 |
825519.01 |
|
B13 |
|
827237.94 |
825301.02 |
|
B14 |
Ma Wan Beach |
824431.47 |
823415.85 |
|
B24 |
Big |
843474.09 |
811730.33 |
|
B25 |
Rocky |
844030.05 |
810286.64 |
|
B26 |
Shek O Beach |
843891.17 |
809864.31 |
|
F1 |
Tung Lung Chau Fish Culture Zone |
847571.26 |
813102.00 |
|
F5 |
Ma Wan Fish Culture Zone |
823875.25 |
823699.48 |
|
WSD5 |
Tsing Yi flushing water intake |
829862.33 |
823104.16 |
|
WSD6 |
Cheung Sha Wan flushing water intake |
833991.16 |
820235.42 |
|
WSD7 |
Kowloon South flushing water intake |
833968.78 |
818053.54 |
|
WSD9 |
Tai Wan flushing water intake |
837955.17 |
818412.01 |
|
WSD10 |
Cha Kwo Ling flushing water intake |
841379.00 |
817859.28 |
|
WSD11 |
Yau Tong flushing water intake |
842149.61 |
816974.14 |
|
WSD12 |
Tsueng Kwan O flushing water intake |
845512.14 |
817421.15 |
|
WSD13 |
Siu Sai Wan flushing water intake |
843904.21 |
814469.38 |
|
WSD15 |
Sai Wan Ho flushing water intake |
841215.41 |
816451.38 |
|
WSD17 |
|
839685.64 |
817081.46 |
|
WSD18 |
Central Water Front flushing water intake |
833935.18 |
816624.15 |
|
WSD19 |
Sheung Wan flushing water intake |
833383.13 |
816836.34 |
|
WSD20 |
|
830826.34 |
816244.46 |
|
WSD22 |
Wan Chai flushing water intake |
836246.19 |
816134.92 |
|
VM12 |
Gradient Station |
830542.34 |
821139.51 |
|
VM14 |
Gradient Station |
829254.66 |
825159.72 |
|
VM15 |
Gradient Station |
832707.02 |
818964.77 |
|
VM8 |
Gradient Station |
830363.95 |
817092.23 |
|
VM7 |
Gradient Station |
832495.44 |
817473.60 |
|
VM5 |
Gradient Station |
836091.75 |
816541.13 |
|
VM2 |
Gradient Station |
839713.80 |
817641.47 |
|
VM4 |
Gradient Station |
838056.49 |
817637.50 |
|
VM1 |
Gradient Station |
841809.43 |
816567.96 |
|
JM3 |
Gradient Station |
844931.70 |
816956.95 |
|
EM1 |
Gradient Station |
844379.62 |
815140.61 |
|
EM2 |
Gradient Station |
845472.92 |
813712.75 |
|
EM3 |
Gradient Station |
845771.79 |
810953.82 |
|
MM13 |
Control Station |
864290.82 |
808693.11 |
|
SM17 |
Control Station |
814115.31 |
801690.83 |
|
Case 3 - Emergency Discharge of
Undisinfected CEPT Effluent via the SCISTW Outfall |
|||
|
B7 |
Anglers’ Beach |
809640.82
|
833462.67
|
|
B8 |
|
809492.93
|
836402.69
|
|
B9 |
Ho Mei Wan Beach |
806868.38
|
851275.55
|
|
B10 |
|
801678.43
|
826182.25
|
|
B11 |
|
825917.78 |
825385.83 |
|
B12 |
|
826277.40 |
825519.01 |
|
B13 |
|
827237.94 |
825301.02 |
|
B14 |
Ma Wan Beach |
824431.47 |
823415.85 |
|
F5 |
Ma Wan Fish Culture Zone |
823875.25 |
823699.48 |
|
WSD18 |
Central Water Front |
833935.18 |
816624.15 |
|
WSD19 |
Sheung Wan |
833383.13 |
816836.34 |
|
WSD20 |
|
830826.34 |
816244.46 |
|
WM4 |
Gradient Station |
825354.99 |
823325.61 |
|
VM8 |
Gradient Station |
830363.95 |
817092.23 |
|
VM7 |
Gradient Station |
832495.44 |
817473.60 |
|
SM6 |
Control Station |
826179.81 |
805902.89 |
|
SM12 |
Control Station |
819524.17 |
808420.40 |
|
Case 4 - Bypass of Screened Sewage from NWKPTW at
the Seawall of |
|||
|
B7 |
Anglers’ Beach |
809640.82 |
833462.67 |
|
B8 |
|
809492.93 |
836402.69 |
|
B9 |
Ho Mei Wan Beach |
806868.38 |
851275.55 |
|
B10 |
|
801678.43 |
826182.25 |
|
B11 |
|
825917.78 |
825385.83 |
|
B12 |
|
826277.40 |
825519.01 |
|
B13 |
|
827237.94 |
825301.02 |
|
B14 |
Ma Wan Beach |
824431.47 |
823415.85 |
|
F5 |
Ma Wan Fish Culture Zone |
823875.25 |
823699.48 |
|
VM14 |
Gradient Station |
829254.66 |
825159.72 |
|
WM4 |
Gradient Station |
825354.99 |
823325.61 |
|
SM6 |
Control Station |
826179.81 |
805902.89 |
|
SM12 |
Control Station |
819524.17 |
808420.40 |
4.58
It should be noted that the temporary
sewage bypass (Case 2 and Case 4) will be conducted under the dry season to
minimize the water quality impacts. A three-month baseline monitoring programme
covering the dry season is proposed at a frequency of once per month to
establish the baseline water quality conditions at the designated stations before
prior to the temporary sewage bypass during the construction phase or early
commissioning of the Project. A six-month
baseline monitoring programme covering both dry and wet seasons is proposed at
a frequency of once per month to establish the baseline water quality
conditions at the 56 stations (for Case 1) and 17 stations (for Case 3) after commissioning
of the Project. During each monitoring
event, water samples shall be collected at different tidal status (one for mid-flood
tide and one for mid-ebb tide). The
purpose of the baseline monitoring is to establish ambient conditions when the HATS
is operated normally. The baseline
monitoring shall be ceased in the events of any emergency discharges.
4.59
During each sampling occasion, measurements
shall be taken at three water depths, namely, 1 m below water surface,
mid-depth and 1 m above sea bed, except where the water depth is less than 6 m,
in which case the mid-depth station may be omitted. Shall the water depth be less than 3 m, only
the mid-depth station will be monitored.
4.60
In the event of temporary sewage bypass or emergency
discharge, daily marine water monitoring shall be conducted at the designated
monitoring stations as shown in Table
4.4 throughout the whole sewage discharge period until the baseline water
quality resumes after the normal plant operation is restored. During each monitoring event, water samples
shall be collected at both mid-flood tide and mid-ebb tide (i.e. twice a day).
4.61
The monitoring programme for Case 1 and
Case 3 shall be conducted in the first 2 years after the completion of the
baseline monitoring. After the 2-year
monitoring period, a review shall be conducted by the Environmental Consultant
to determine whether such monitoring shall be continued. The review results shall be submitted to DSD
and EPD. Termination or any amendment to
the monitoring programme shall be agreed by DSD and EPD.
4.62
The status and locations of water sensitive
receivers and the marine activities may change after issuing this Manual. Necessary change in the monitoring locations
shall be reviewed and approved by EPD, before the commencement of the
monitoring. It is recommended that DSD should monitor the
quality (i.e. E.coli level, pH value, temperature) and quantity of sewage effluent
discharged from the SCISTW during the marine water sampling for data
interpretation.
4.63
It is recommended that relevant government
departments including EPD, WSD and LCSD shall be informed of any emergency
discharge events. The Plant operators
shall make reference to the response approach documented in the Beach Pollution
Response Plan maintained by EPD and maintain good communications with various
concerned parties. A list of address,
email address, phone and fax number of key persons in various departments responsible
for action shall be made available to the Plant operators. A framework of the emergency response is
provided in Table 4.5.
Laboratory
Measurement / Analysis
4.64
The suggested analysis method and detection
limit are presented in Table 4.6.
Emergency
Response
General Requirement
4.65
The Plant operator / DSD shall inform EPD, WSD and LCSD in
case of any emergency discharge of undisinfected effluent due to power supply
failure or equipment failure in SCISTW. The
Plant operator / DSD shall inform EPD, WSD and LCSD at least 4 weeks prior to
the planned temporary sewage bypass during construction phase or early
commissioning of the Project. A list of
address, email address, phone and fax number of key persons of concerned
parties responsible for action should be made available to the Plant
operators. The Plant operator / DSD
shall closely liaise with relevant parties so that the EPD, WSD and LCSD can be
informed promptly of any cases of temporary sewage bypass or emergency
discharge. The event and action plan
under temporary sewage bypass and emergency discharge are provided in Table
4.5.
4.66
Under temporary sewage bypass and emergency discharge, it is
recommended that DSD should monitor daily quality (i.e. E.coli level, pH value,
temperature) and quantity of sewage effluent discharged from the SCISTW during
the whole water quality monitoring period for data interpretation.
Table 4.5 Emergency Response Plan for Temporary Sewage Bypass
and Emergency Discharge from HATS
|
Event |
Action Plan |
|
Case 1 - Total power / equipment failure at SCISTW
during operational phase |
1.
Plant
operators / DSD to investigate the reason of plant failure and to implement
appropriate remedial measures as stipulated in the contingency / operation
plan for the HATS. 2.
If
emergency discharge is required, Plant operators / DSD to inform EPD, WSD and
LCSD within 1 hour after the discharge commence. 3.
Plant
operators / DSD to instruct the Monitoring Team to commence water monitoring
within 24 hours after the emergency discharge event occurs. 4.
Plant operators
/ DSD to record the effluent flow and effluent quality (i.e. E.coli level, pH value, temperature,
salinity, turbidity and dissolved oxygen) during the water monitoring period. 5.
Plant
operators / DSD to ensure appropriate remedial measures as stipulated in the
contingency / operation plan are implemented. 6.
Monitoring
Team to conduct daily marine water monitoring (as discussed in Section
3.2.15) until the baseline water quality levels are restored or 3 days after
the emergency discharge is ceased, whichever is the shortest. 7. The Environmental Consultant shall compare the
impact monitoring data with the baseline data to identify the degree of
impact caused by the emergency discharge (if any) and to determine when the
normal water quality conditions are restored.
The findings shall be provided to EPD, WSD and LCSD. |
|
Case 2/Case 4 - Temporary sewage bypass during
construction phase |
1.
If temporary
sewage bypass is required, Plant operators / DSD to inform EPD, WSD and LCSD at
least 4 weeks prior to the discharge. 2.
Environmental
Team to conduct daily marine water monitoring (as discussed in Section
3.2.15) until the baseline water quality levels are restored or 3 days after
the emergency discharge is ceased, whichever is the shortest. 3.
Plant
operators / DSD to record the effluent flow and effluent quality (i.e. E.coli level, pH value, temperature,
salinity, turbidity and dissolved oxygen) during the water monitoring period. 4.
The IEC shall
compare the impact monitoring data with the baseline data to identify the
degree of impact caused by the temporary sewage discharge (if any) and to
determine when the normal water quality conditions are restored. The findings shall be provided to EPD, WSD
and LCSD. |
|
Case 3 - Chlorination plant failure during
operational phase |
1.
Stop the
dechlorination plant operation 15 minutes after the chlorination plant
failure. 2.
If
emergency discharge is required, Plant operators / DSD to inform EPD, WSD and
LCSD within 1 hour after the discharge commence. 3.
Plant
operators / DSD to investigate the reason of chlorination plant failure and
to implement appropriate remedial measures as stipulated in the contingency /
operation plan for the HATS. 4.
Plant
operators / DSD to instruct the Monitoring Team to commence water monitoring
within 24 hours after the emergency discharge event occurs. 5.
Plant
operators / DSD to record the effluent flow and effluent quality (i.e. E.coli level, pH value and
temperature) during the water monitoring period. 6.
Plant
operators / DSD to implement appropriate remedial measures as stipulated in
the contingency / operation plan and resume disinfection operation. 7.
Monitoring
Team to conduct daily marine water monitoring (as discussed in Section 4.8)
until the baseline water quality levels are restored or 3 days after the
emergency discharge is ceased, whichever is the shortest. 8.
The
Environmental Consultant shall compare the impact monitoring data with the
baseline data to identify the degree of impact caused by the emergency
discharge (if any) and to determine when the normal water quality conditions
are restored. The findings shall be
provided to EPD, WSD and LCSD. |
|
Case 3 - Dechlorination plant failure during
operational phase |
1. Stop the chlorination plant operation immediately. 2. Plant operator / DSD to inform the EPD, WSD and LCSD
of the emergency discharge within 1 hour after the chlorination plant
operation is stopped. 3. Plant operators / DSD to investigate the reason of
dechlorination plant failure and to implement appropriate remedial measures
as stipulated in the contingency / operation plan for the HATS. 4. Plant operators / DSD to instruct the Monitoring
Team to commence water monitoring within 24 hours after the emergency
discharge event occurs. 5. Plant operators / DSD to record the effluent flow
and effluent quality (i.e. E.coli level, pH value, and temperature) recorded during the water monitoring period. 6. Plant operators / DSD to implement appropriate
remedial measures as stipulated in the contingency / operation plan and
resume disinfection operation. 7. Monitoring Team to conduct daily marine water
monitoring (as discussed in Section 4.8) until the baseline water quality
levels are restored or 3 days after the emergency discharge is ceased,
whichever is the shortest. 8. The Environmental Consultant shall compare the
impact monitoring data with the baseline data to identify the degree of
impact caused by the emergency discharge (if any) and to determine when the
normal water quality conditions are restored.
The findings shall be provided to EPD, WSD and LCSD. |
4.67
The impact monitoring data shall be compared with the
baseline data and relevant water quality objectives to identify the degree of
impact caused by the temporary sewage bypass or emergency discharge. For each emergency discharge event during
operational phase, a Water Quality Monitoring
Report shall be submitted by the Environmental Consultant to EPD within 10
days after the laboratory testing result for the last sample collected during
the monitoring period is available. Similarly,
for the planned temporary sewage bypass event during construction phase, a Water Quality Monitoring Report shall be
submitted by the IEC to EPD within 10 days after the laboratory testing result
for the last sample collected during the monitoring period is available. The
findings of the water quality monitoring results including data presentation,
statistical analysis, discussion, conclusion and recommendation shall be
provided in the Water Quality Monitoring
Report. The detailed reporting
requirements shall be agreed with DSD and EPD.
Dissolved Oxygen and Temperature Measuring Equipment
4.68
The instrument shall be a portable and
weatherproof DO measuring instrument complete with cable and sensor, and use a
DC power source. The equipment shall be
capable of measuring:
·
a DO level in the range of 0 ‑ 20 mg
L-1 and 0 ‑ 200% saturation; and
·
a temperature of 0 ‑ 45 degree
Celsius.
4.69
It shall have a membrane electrode with
automatic temperature compensation complete with a cable. Sufficient stocks of
spare electrodes and cables shall be available for replacement where necessary.
(For example, YSI model 59 meter, YSI 5739 probe, YSI 5795A submersible stirrer
with reel and cable or an approved similar instrument).
4.70
Shall salinity compensation not be built-in
to the DO equipment, in-situ salinity
shall be measured to calibrate the DO equipment prior to each DO measurement.
4.71
Turbidity shall be measured in situ
by the nephelometric method. The instrument shall be portable and weatherproof
turbidity measuring instrument using a DC power source complete with cable,
sensor and comprehensive operation manuals.
It shall have a photoelectric sensor capable of measuring turbidity
between 0 - 1000 NTU. The cable shall not be less than 25m in length. The meter
shall be calibrated in order to establish the relationship between NTU units
and the levels of suspended solids.
4.72
A water sampler is required. It shall comprise a transparent PVC cylinder,
with a capacity of not less than 2 litres, which can be effectively sealed with
latex cups at both ends. The sampler
shall have a positive latching system to keep it open and prevent premature
closure until released by a messenger when the sampler is at the selected water
depth (for example, Kahlsico Water Sampler or an approved similar instrument).
4.73
A portable, battery-operated echo sounder
shall be used for the determination of water depth at each designated
monitoring station. This unit can either
be hand held or affixed to the bottom of the work boat, if the same vessel is
to be used throughout the monitoring programme.
4.74
A portable salinometer capable of measuring
salinity in the range of 0 - 40 parts per thousand (ppt) shall be provided for
measuring salinity of the water at each monitoring location.
4.75
The instrument shall consist of a
potentiometer, a glass electrode, a reference electrode and a
temperature-compensating device. It shall be readable to 0.1pH in a range of 0
to 14. Standard buffer solutions of at least pH 7 and pH 10 shall be used for calibration
of the instrument before and after use. Details of the method shall comply with
APHA, 19th ed. 4500-HTB.
4.76
A hand-held or boat-fixed type digital
Differential Global Positioning System (DGPS) with way point bearing indication
or other equipment instrument of similar accuracy, shall be provided and used
during marine water monitoring to ensure the monitoring vessel is at the
correct location before taking measurements.
4.77
All in situ monitoring instruments
shall be checked, calibrated and certified by a laboratory accredited under
HOKLAS or any other international accreditation scheme before use and
subsequently re-calibrated at three monthly intervals throughout all stages of
the water quality monitoring programme.
Responses of sensors and electrodes shall be checked with certified
standard solutions before each use. Wet
bulb calibration for a DO meter shall be carried out before measurement.
4.78
Sufficient stocks of spare parts shall be
maintained for replacements when necessary.
Backup monitoring equipment shall also be made available so that
monitoring can proceed uninterrupted even when some equipment is under
maintenance, calibration, etc.
4.79
Water samples shall be stored and preserved
in suitable containers according to the Standard Methods, APHA, and packed in
ice (cooled to 4°C without being frozen) and delivered to the laboratory and
analysed within 24 hours after collection.
Sufficient volume of samples shall be collected to achieve the required
detection limit.
4.80
Other relevant data shall also be recorded,
including monitoring location / position, time, water depth, pH value,
salinity, temperature, turbidity, dissolved oxygen, tidal stages, weather
conditions and any special phenomena or work underway nearby which may induce
water quality impact on the sensitive receivers. A sample data record
sheet based on the one presented in the EM&A
Guidelines for Development Projects in Hong Kong, is shown in Appendix B. The Monitoring Team Leader may modify the
data record sheet for this EM&A programme, the format of which should be
approved by the Environmental Consultant.
4.81
Analysis of marine water quality and effluent
quality as listed in Table 4.6 shall
be carried out in a HOKLAS or other international accredited laboratory. The analysis shall commence within 24 hours
after collection of the effluent samples.
Detailed testing methods, pre-treatment procedures, instrument use,
Quality Assurance/Quality Control (QA/QC) details (such as blank, spike
recovery, number of duplicate samples per batch, etc.), detection limits and
accuracy shall be submitted to the Environmental Consultant for approval prior
to the commencement of monitoring programme.
If in-house or non-standard methods are proposed, details of the method
verification shall be required to submit to Environmental Consultant. In any circumstance, the sample testing shall
have comprehensive quality assurance and quality control programmes. The laboratory shall prepare to demonstrate
the programmes to Environmental Consultant or his representatives when
requested.
Table
4.6 Suggested Analytical Methods
and Detection Limit
|
Determinant |
Suggested Method |
Suggested Detection Limit |
||
|
Total
residual chlorine |
APHA 4500CL: G |
5 mg/L * |
||
|
Bromoform |
Tri- halomethanes (THMs) |
USEPA 8260 (Purge & Trap GCMS) |
0.1 mg/L * |
|
|
Bromodichloromethane |
0.1 mg/L * |
|||
|
Chloroform |
0.1 mg/L * |
|||
|
Dibromochloromethane |
5 mg/L |
|||
|
Bromoacetic
acid |
Halo-acetic Acids (HAAs) |
APHA 6251 |
2 mg/L |
|
|
Chloroacetic
acid |
2 mg/L |
|||
|
Dibromoacetic
acid |
2 mg/L |
|||
|
Dichloroacetic
acid |
2 mg/L |
|||
|
Trichloroacetic
acid |
2 mg/L |
|||
|
Arsenic |
USEPA 200.7 |
1 mg/L |
||
|
Chromium III |
USEPA 200.7 |
1 mg/L |
||
|
Copper |
USEPA 200.7 |
1 mg/L |
||
|
Mercury |
USEPA 200.7 |
0.1 mg/L * |
||
|
Nickel |
USEPA 200.7 |
1 mg/L |
||
|
Zinc |
USEPA 200.7 |
1 mg/L |
||
|
Sulphide |
APHA 20e 4500-S2- |
10 mg/L |
||
|
Total Surfactants |
Surfactants – Anionic (MBAS) |
APHA 5540 C |
0.5 mg/L |
|
|
Surfactants – Non-Ionic |
APHA 5540 B & D |
0.5 mg/L |
||
|
Phenol |
APHA 5530 B & D |
0.2 mg/L |
||
|
Cyanide |
APHA 4500 CN-M |
0.1 mg/L |
||
|
Suspended Solids |
APHA 17ed 2540D |
1 mg/L |
||
|
5-day Biochemical Oxygen
Demand |
APHA 19ed 5210B |
1 mg/L |
||
|
Ammonia Nitrogen |
APHA 19ed 4500-NH3 F |
0.02 mg/L |
||
|
Unionized Ammonia |
By calculation |
0.001 mg/L |
||
|
Total Kjeldahl Nitrogen |
APHA 19ed 4500-Norg |
0.01 mg/L |
||
|
Nitrite-nitrogen |
APHA 19ed 4500-NO2- B |
0.01 mg/L |
||
|
Nitrate-nitrogen |
APHA 19ed 4500-NO3- E |
0.02 mg/L |
||
|
E. coli |
EPD HKSAR, Wat. Sci.
Tech. Vol.35, No. 11-12, pp 409-413 |
1 CFU per
100 ml |
||
|
Orthophosphorus |
APHA 19ed 4500- P.E |
0.01 mg/L |
||
|
Total Phosphorus |
APHA 19ed 4500-P.B.E |
0.01 mg/L |
||
l
The suggested
detection limit was in light of the concentration of interest (COI) for human
health and/or ecological resources, which was based on local/international authority
approved standard. Determinant at
concentration below COI is not expected to induce concern to human health and
ecological resources.
4.82
Regular site audits shall be conducted to confirm
that the recommended mitigation measures are properly undertaken during
construction phase of the Project. It can also provide an effective control of
any malpractices and therefore achieve continual improvement of environmental
performance on site.
4.83
Site audits shall include site inspections
and compliance audits.
Site Inspections
4.84
Site inspections shall be carried out by
the ET on the mitigation measures recommended for water pollution control in
the implementation schedule as attached in Appendix
A. In the event that the recommended mitigation measures are not fully or
properly implemented, deficiency shall be recorded and reported to the ER and
IEC. Suitable follow up actions are to be carried out to:
·
Record the problems and investigate the
causes;
·
Issue action notes to the Contractor who is
responsible for the works;
·
Implement remedial and corrective actions
immediately;
·
Re-inspect the site conditions upon
completion of the remedial and corrective actions; and
·
Record the event and discuss with the
Contractor for preventive actions.
Compliance Audits
·
Notify the ER and IEC of the
non-compliance;
·
Identify the sources of pollution;
·
Check the implementation status of the
recommended mitigation measures;
·
Investigate the operating conditions of the
on-site treatment systems;
·
Implement corrective and remedial actions
to improve the effluent quality;
·
Increase monitoring frequency until the
effluent quality is in compliance with the discharge licence requirements; and
·
Record the non-compliance and propose
preventive measures.
4.86
Mitigation measures for water quality control have been
recommended in the EIA Report and are listed in the implementation schedule
given in Appendix A.
[1] Including Whole Effluent Toxicity
Test (WETT) to be conducted during operation phase of the Project.