4a.1.1.1
This
section describes the requirements for the monitoring and audit of water
quality impact from the Project.
4a.1.1.2
The
water quality assessment undertaken in the EIA Study concluded that the
identified water quality impacts during construction phase of the IWMF would be
minimised by implementing the recommended mitigation measures for the
construction works. Release of PFA leachate due to the foundation construction
would not be likely to accelerate. Marine
water quality monitoring was recommended during the foundation piling of the IWMF
to confirm the assessment results.
4a.1.1.3
Regular
site inspections were recommended to be undertaken to inspect the construction
activities and works areas and also the status on the implementation of the
recommended mitigation measures. In addition, water quality monitoring of
the Tsang Kok Stream was recommended during site formation and foundation
piling of the IWMF, in order to ensure no adverse water quality impact to the
stream.
4a.1.1.4
Discharges
of drainage water from the construction works areas would be required to comply
with the terms and conditions of a discharge licence, issued by EPD, under the
Water Pollution Control Ordinance (WPCO). It may be a stipulation of the
WPCO licence to require the Contractor to monitor the quality / quantity of the
discharge to show compliance with the conditions of the licence. Such
monitoring would not form part of the EM&A programme.
4a.1.1.5
During
the operation phase of the Project, all generated wastewater will be discharged
into an on-site wastewater treatment plant. The treated effluent from the wastewater
treatment plant will be reused for washdown and landscape irrigation in the
IWMF site. A ‘net zero discharge’ scheme
will be adopted during the operation of the IWMF. Saline water would be discharged from the
proposed desalination plant in a low discharge rate. The potential impact associated with saline
water discharge has been quantitatively assessed to be minor and
acceptable. Adverse impacts on water
quality due to the operation of the Project would not be expected. Therefore, no monitoring of water quality
would be required during the operation phase of the IWMF.
4a.2.1.1
Dissolved oxygen
(DO), turbidity, suspended solids (SS) level and pH should be monitored at
designated water quality monitoring stations in the Tsang Kok Stream.
4a.2.1.2
With regard to the
potential marine water quality impact from PFA leachate, heavy metals including
cadmium, chromium and aluminium, which have the greatest tendency to leach from
the lagoon PFA into the seawater, should be monitored.
4a.2.1.3
The levels of DO,
turbidity and pH should be measured in situ whereas SS and heavy metals
should be determined by laboratory analysis.
4a.3.1.1 The proposed water quality monitoring stations are listed in Table 4a.1 and shown in Figures 4a.1 and 4a.2. For the stream water quality monitoring, a monitoring station should be set in the stream course upstream of the works areas which should act as a control station, and two impact monitoring stations should be located in Tsang Kok stream adjacent and downstream of the works areas. In terms of the marine water quality monitoring conducted during the foundation piling, two control stations namely C2 and C3 should be set in the outer marine water and two impact monitoring stations should be located adjacent to the Middle Ash Lagoon in the Deep Bay WCZ. The status and locations of water sensitive receivers and the marine activities may change after issuing this Manual. If such case exists, the ET Leader shall propose updated monitoring locations and seek approval from the IEC and EPD.
Table 4a.1 Proposed Water Quality Monitoring Stations
Station |
Description |
Easting |
Northing |
Parameters |
C1 |
Control station for the
Tsang Kok stream water quality monitoring |
809963 |
830960 |
DO, turbidity, SS, pH |
S1 |
Impact monitoring
stations for the Tsang Kok stream |
810042 |
831065 |
|
S2 |
810301 |
831190 |
||
C2 |
Control station for
marine water quality monitoring |
811225 |
833018 |
cadmium; chromium;
aluminium |
C3 |
808281 |
832684 |
||
M1 |
Marine water adjacent to
the Middle Ash Lagoon |
809527 |
831656 |
|
M2 |
810131 |
831818 |
4a.3.1.2
For the stream
water quality monitoring, measurement should be taken at mid-depth layer.
For the marine water monitoring stations, sampling shall be taken at three
water depths, namely, 1m below water surface, mid-depth and 1m above seabed,
except at 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.
4a.1.1.1
Baseline conditions
in the stream course and marine water should be established and agreed with EPD
prior to the commencement of construction works. The purpose of the
baseline monitoring is to establish ambient conditions prior to the
commencement of the works and to demonstrate the suitability of the proposed
monitoring stations. The baseline conditions should normally be
established by measuring the water quality parameters specified in Table 4a.2.
4a.1.1.2
The baseline
monitoring for the stream course should be taken at all designated monitoring
stations in the Tsang Kok Stream, three days per week, for at least 4 weeks
prior to the commencement of construction works. There should not be any
construction activities in the vicinity of the stations during the baseline
monitoring. The interval between 2 sets of monitoring should not be less than
36 hours. Duplicate in-situ measures
should be carried out in each sampling event.
4a.1.1.3
The baseline
monitoring for marine water should be taken at all
designated monitoring stations, 3 days per week, at mid-flood and mid-ebb tides, for at least 4 weeks prior to the
commencement of construction works.
There should not be any construction activities in the vicinity of the
stations during the baseline monitoring.
The interval between 2 sets of monitoring should not be less than 36
hours.
4a.1.1.4
Baseline monitoring
schedule should be submitted to EPD at least 4 weeks prior to the commencement
of baseline monitoring. EPD should also be
notified immediately for any changes in schedule.
4a.1.1.5 The baseline monitoring report should be submitted to EPD at least 4 weeks before the commencement of the construction works for agreement. The baseline monitoring report should be certified by the IEC before submission to EPD.
4a.2.1 Stream Water Quality Monitoring
4a.2.1.1
During the course
of site formation and foundation piling of the IWMF, impact monitoring should
be undertaken three days per week with sampling / measurement at the designated
monitoring stations in the Tsang Kok Stream. Upon completion of the above
construction works, the monitoring exercise at the designated monitoring
locations should be continued for four weeks in the same manner as the impact
monitoring. The
interval between two sets of monitoring should not be less than 36 hours except
where there are exceedances of Action and/or Limit Levels, in which case the
monitoring frequency will be increased. Table
4a.2 shows the proposed monitoring frequency and water
quality parameters.
4a.2.1.2
Duplicate in-situ measurements should be carried out in each sampling
event. The monitoring probes should be retrieved out of water after the first
measurement and then redeployed for the second measurement. Where the
difference in value between the first and second readings of DO, turbidity or pH is more than 25% of the value of the first reading, the reading should
be discarded and further readings should be taken.
4a.2.1.3 The water quality monitoring schedule should be submitted to EPD at least 1 week before the first day of the monitoring month. EPD should be notified immediately of any changes in schedule by fax. If the monitoring data collected at the designated stations indicate that the Action or Limit Levels as shown in Table 4a.4 are exceeded, appropriate actions should be taken in accordance with the Event and Action Plan in Table 4a.5.
4a.2.2 Marine Water Quality Monitoring
4a.2.2.1
During the
foundation piling and other construction works of the IWMF, impact monitoring
should be undertaken three days per week at mid-flood and mid-ebb tides with sampling / measurement at the designated
monitoring stations in the Deep Bay WCZ. Upon completion of the piling or
construction works, the monitoring exercise at the designated monitoring
locations should be continued for four weeks in the same manner as the impact
monitoring. The interval between two sets of monitoring should not be less than
36 hours except where there are exceedances of Action and/or Limit Levels, in
which case the monitoring frequency will be increased. Table
4a.2 shows the proposed monitoring frequency and water
quality parameters.
Table 4a.2 Proposed Marine Water Quality Monitoring Frequency and Parameters
Activities |
Monitoring Frequency
|
Key Parameters
|
Monitoring Station |
During
the 4-week baseline monitoring period |
Three
days per week |
Suspended
Solids (SS), Turbidity and Dissolved Oxygen (DO), pH |
C1,
S1, S2 |
cadmium, chromium and
aluminium |
C2, C3, M1, M2 |
||
During the course of
site formation and foundation piling of the IWMF |
Three days per week |
Suspended Solids
(SS), Turbidity and Dissolved Oxygen (DO), pH |
C1, S1, S2 |
During the foundation
piling work |
Three days per week |
cadmium, chromium and
aluminium |
C2, C3, M1, M2 |
During a 4-week
period after completion of construction works |
Three days per week |
Suspended Solids
(SS), Turbidity and Dissolved Oxygen (DO), pH |
C1, S1, S2 |
During a 4-week
period after completion of foundation piling work |
Three days per week |
cadmium, chromium and
aluminium |
C2, C3, M1, M2 |
Notes: 1. DO, turbidity and pH
should be measured in situ whereas SS
and metals should be determined by laboratory.
4a.3.1.1 Implementation of regular site audits is to ensure that the recommended mitigation measures are to be properly undertaken during proposed construction works. It can also provide an effective control of any malpractices and therefore achieve continual improvement of environmental performance on site.
4a.3.1.2 Site audits shall be carried out by the ET and shall be based on the mitigation measures for water pollution control recommended in the implementation schedule as presented in Appendix 12.1. In the event that the recommended mitigation measures are not fully or properly implemented, deficiency shall be recorded and reported to the site management. Suitable actions are to be carried out to:
· investigate the problems and 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.
4a.4.1.1 Other relevant data should also be recorded, including monitoring location / position, time, water depth, sampling depth, pH, salinity, DO saturation, water temperature, tidal stages, weather conditions and any special phenomena or work underway nearby.
4a.4.1.2 A sample data record sheet is shown in Appendix 4a.1 for reference.
4a.5.1 Dissolved Oxygen and Temperature Measuring Equipment
4a.5.1.1
The instrument
should be a portable and weatherproof DO measuring instrument complete with
cable and sensor, and use a DC power source. The equipment should be
capable of measuring:
· a DO level in the range of 0 ‑ 20 mg/L and 0 ‑ 200% saturation; and
· a temperature of 0 ‑ 45 degree Celsius.
4a.5.2 Turbidity Measurement Instrument
4a.5.2.1
The instrument
should be a portable and weatherproof turbidity-measuring instrument using a DC
power source. It should have a photoelectric sensor capable of measuring
turbidity between 0 - 1000 NTU (for example, Hach model 2100P or an approved
similar instrument).
4a.5.3 pH Measurement Instrument
4a.5.3.1
The instrument
should consist of a potentiometer, a glass electrode, a reference electrode and
a temperature-compensating device. It should be readable to 0.1pH in a
range of 0 to 14. Standard buffer solutions of at least pH 7 and pH 10
should be used for calibration of the instrument before and after use.
4a.5.4.1
A water sampler is
required. It should 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 should 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).
4a.5.5.1
A portable,
battery-operated echo sounder should 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.
4a.5.6 Sample Containers and Storage
4a.5.6.1
Water samples for
SS and three heavy metals measurements should be stored in high density
polythene bottles with no preservative added, packed in ice (cooled to 4°C
without being frozen) and delivered to the laboratory and analysed as soon as
possible after collection. Sufficient volume of samples should be
collected to achieve the detection limit stated in Section 4a.9.
4a.5.7 Monitoring Position Equipment
4a.5.7.1
A hand-held or
boat-fixed type digital Differential Global Positioning System (DGPS) with way
point bearing indication and Radio Technical Commission for maritime (RTCM)
Type 16 error message ‘screen pop-up’ facilities (for real-time auto-display of
error messages and DGPS corrections from the Hong Kong Hydrographic Office), or
other equipment instruments of similar accuracy, should be provided and used to
ensure that the water sampling locations are correct during the water quality
monitoring work.
4a.5.8 Calibration of In-Situ Instruments
4a.5.8.1
The DO meter and
turbidimeter should be checked and calibrated before use. DO meter and
turbidimeter should be certified by a laboratory accredited under HOKLAS or any
other international accreditation scheme, and subsequently re-calibrated at
three monthly intervals throughout all stages of the water quality
monitoring. Responses of sensors and electrodes should be checked with
certified standard solutions before each use. Wet bulb calibration for a
DO meter should be carried out before measurement at each monitoring location.
4a.5.8.2
Sufficient stocks
of spare parts should be maintained for replacements when necessary.
Backup monitoring equipment should also be made available so that monitoring
can proceed uninterrupted even when some equipment is under maintenance,
calibration, etc.
4a.6 Laboratory Measurement / Analysis
4a.6.1.1
Analysis of
suspended solids (SS) and heavy metals should be carried out in a HOKLAS or
other international accredited laboratory. Sufficient water samples
should be collected at the monitoring stations for carrying out the laboratory
determinations. The determination work should start within 24 hours after
collection of the water samples. The analyses should follow the American
Public Health Association (APHA) Standard Methods for the Examination of Water
and Wastewater or an equivalent method subject to the approval of EPD.
Analytical methods and detection limits for SS and heavy metals are present in Table 4a.3.
Table 4a.3 Analytical Methods to be Applied to Water Quality Samples
Parameters |
Analytical
Method |
Detection
Limit |
Suspended Solids |
APHA 2540D * |
1 mg/L |
Cadmium |
APHA 20e
3111B * |
0.5
μg/L |
Chromium |
APHA 20e
3111D * |
1 μg/L |
Aluminium |
APHA
3500-Al-D * |
20 μg/L |
* APHA American
Public Health Association Standard Methods for the Examination of Water and
Wastewater
4a.6.1.2 The testing of SS and metals should be HOKLAS accredited (or if not, approved by EPD) and comprehensive quality assurance and control procedures in place in order to ensure quality and consistency in results.
4a.6.1.3
Detailed testing methods,
pre-treatment procedures, instruments use, Quality Assurance / Quality Control
(QA/QC) details (such as blank, spike recovery, number of duplicate samples per
batch, etc.), detection limit and accuracy shall be submitted to EPD for
approval prior to the commencement of monitoring programme. EPD may also request the laboratory to carry
out analysis of known standards provided by EPD for quality assurance. The QA/QC shall be in accordance with the
requirements of HOKLAS or international accredited scheme. The QA/QC results shall be reported. The testing methods and related proposal
should be checked and certified by IEC before submission to EPD for approval.
4a.6.1.4
Additional
duplicate samples may be required by EPD for inter-laboratory
calibration. Remaining samples after analysis should be kept by the
laboratory for 3 months in case repeat analysis is required. If in-house
or non-standard methods are proposed, details of the method verification may
also be required to submit to EPD. In any circumstance, the sample
testing should have comprehensive quality assurance and quality control
programmes. The laboratory should prepare to demonstrate the programme to
DEP or his representatives when requested.
4a.7.1.1
The water quality
criteria, namely action and limit levels, are shown in Table 4a.4. These criteria should be applied to ensure
that any deterioration of water quality is readily detected and timely action
is taken to rectify the situation. Should the monitoring results of the
water quality parameters at any designated monitoring station exceed the water
quality criteria, the actions in accordance with the Event and Action Plan
summarized in Table
4a.5 shall be carried out.
4a.7.1.2 The ET Leader should assess the potential impacts on the water sensitive receivers based on the monitoring data. The performance of the environmental management system (i.e. of the overall EM&A programme) should be reviewed by the ET Leader on a quarterly basis. The findings of this review should be included in the quarterly EM&A summary reports, together with any recommendations to improve the performance of the EM&A programme.
Table 4a.4 Action and Limit Levels for Water Quality
Parameters |
Action |
Limit |
DO in mg/L |
£ 5 %-ile of baseline data |
£ 4 mg/L |
SS in mg/L |
≥ 95 %-ile of baseline data or 120% of control station’s SS on
the same day of measurement |
≥ 99 %-ile of baseline or 130% of control station's SS on the
same day of measurement |
Turbidity in NTU |
≥ 95 %-ile of baseline data or 120% of control station’s
turbidity on the same day of measurement |
≥ 99 %-ile of baseline or 130% of control station's turbidity on
the same day of measurement |
pH |
=<5 %-ile or >=95 %-ile of baseline
data |
pH £ 6 or pH ≥ 9 |
Cadmium |
≥ 95 %-ile of baseline data |
≥ 99 %-ile of baseline |
Chromium |
≥ 95 %-ile of baseline data |
≥ 99 %-ile of baseline |
Aluminium |
≥ 95 %-ile of baseline data |
≥ 99 %-ile of baseline |
Notes:
1. For DO, non-compliance of the
water quality limits occurs when monitoring result is lower than the limits.
2. For metals, SS and turbidity, non-compliance of the water quality limits
occurs when monitoring result is higher than the limits.
4a.8.1.1
Mitigation measures
for water quality control have been recommended in the EIA Report and listed in
the implementation schedule given in Appendix 12.1.
4a.8.1.2
In the event of
complaints or non-compliance / area of improvement being observed, the ET and
the Contractor should review the effectiveness of these mitigation measures,
design alternative or additional mitigation measures as appropriate and propose
to the IEC for approval and implement these alternative or additional measures.
Table 4a.5 Event and Action Plan for Water Quality
Event |
ET Leader |
IEC |
ER |
Contractor |
Action level
being exceeded by one sampling day |
·
Repeat in situ measurement to
confirm findings; · Identify
reasons for non-compliance and source(s) of impact; · Inform
IEC and Contractor; · Check
monitoring data, all plant, equipment and Contractor's working methods; · Discuss
mitigation measures with IEC and Contractor; ·
Repeat measurement on next day of
exceedance. |
· Discuss
with ET and Contractor on the mitigation measures; · Review
proposals on mitigation measures submitted by Contractor and advise the ER accordingly; · Assess
the effectiveness of the implemented mitigation measures. |
· Discuss
with IEC on the proposed mitigation measures; · Make
agreement on the mitigation measures to be implemented. · Assess
the effectiveness of the implemented mitigation measures. |
· Inform
the ER and confirm notification of the non-compliance in writing; · Rectify
unacceptable practice; · Check
all plant and equipment; · Consider
changes of working methods; · Discuss
with ET and IEC and propose mitigation measures to IEC and ER; · Implement
the agreed mitigation measures. |
Action level
being exceeded by more than one consecutive sampling day |
· Repeat
in situ measurement to confirm
findings; · Identify
reasons for non-compliance and source(s) of impact; · Inform
IEC and Contractor; · Check
monitoring data, all plant, equipment and Contractor's working methods; · Discuss
mitigation measures with IEC and Contractor; · Ensure
mitigation measures are implemented; · Prepare
to increase the monitoring frequency to daily; · Repeat
measurement on next day of exceedance. |
· Discuss
with ET and Contractor on the mitigation measures; · Review
proposals on mitigation measures submitted by Contractor and advise the ER
accordingly; · Assess
the effectiveness of the implemented mitigation measures. |
· Discuss
with IEC on the proposed mitigation measures; · Make
agreement on the mitigation measures to be implemented; · Assess
the effectiveness of the implemented mitigation measures. |
· Inform
the ER and confirm notification of the non-compliance in writing; · Rectify
unacceptable practice; · Check
all plant and equipment; Consider changes of working methods; · Discuss
with ET and IEC and propose mitigation measures to IEC and ER within three
working days; · Implement
the agreed mitigation measures. |
Limit level
being exceeded by one sampling day |
· Repeat
in situ measurement to confirm
findings; · Identify
reasons for non-compliance and source(s) of impact; · Inform
IEC Contractor and EPD; · Check
monitoring data, all plant, equipment and Contractor's working methods; · Discuss
mitigation measures with IEC, ER and Contractor; · Ensure
mitigation measures are implemented; · Increase
the monitoring frequency to daily until no exceedance of Limit level. |
· Discuss
with ET and Contractor on the mitigation measures; · Review
proposals on mitigation measures submitted by Contractor and advise the ER
accordingly; · Assess
the effectiveness of the implemented mitigation measures. |
· Discuss
with IEC, ET and Contractor on the proposed mitigation measures; · Request
Contractor to critically review the working methods; · Make
agreement on the mitigation measures to be implemented; · Assess
the effectiveness of the implemented mitigation measures. |
· Inform
the ER and confirm notification of the non-compliance in writing; · Rectify
unacceptable practice; · Check
all plant and equipment; · Consider
changes of working methods; · Discuss
with ET, IEC and ER and propose mitigation measures to IEC and ER within
three working days; · Implement
the agreed mitigation measures. |
Limit level
being exceeded by more than one consecutive sampling day |
· Repeat
in situ measurement to confirm
findings; · Identify
reasons for non-compliance and source(s) of impact; · Inform
IEC Contractor and EPD; · Check
monitoring data, all plant, equipment and Contractor's working methods; · Discuss
mitigation measures with IEC, ER and Contractor; · Ensure
mitigation measures are implemented; · Increase
the monitoring frequency to daily until no exceedance of Limit level for two
consecutive days. |
· Discuss
with ET and Contractor on the mitigation measures; · Review
proposals on mitigation measures submitted by Contractor and advise the ER
accordingly; · Assess
the effectiveness of the implemented mitigation measures. |
· Discuss
with IEC, ET and Contractor on the proposed mitigation measures; · Request
Contractor to critically review the working methods; · Make
agreement on the mitigation measures to be implemented; · Assess
the effectiveness of the implemented mitigation measures; · Consider
and instruct, if necessary, the Contractor to slow down or to stop all or
part of the construction activities until no exceedance of Limit level. |
· Inform
the ER and confirm notification of the non-compliance in writing; · Rectify
unacceptable practice; · Check
all plant and equipment; · Consider
changes of working methods; · Discuss
with ET, IEC and ER and propose mitigation measures to IEC and ER within
three working days; · Implement
the agreed mitigation measures; · As
directed by the ER, to slow down or to stop all or part of the construction
activities. |