3. Water Quality
3.1 Introduction
3.2 Emergency Discharge
3.3 Construction Phase Monitoring
3.4 Post Project Water Quality Monitoring during Operation
Phase
3.5 Mitigation Measures
List of Tables
Table 3.1 Proposed Water Quality Monitoring Stations
Table 3.2 Analytical Method to be applied to Marine Water Quality Samples
Table 3.3 Emergency Response Plan for Discharge of Untreated or Partially
Treated Effluent from PPSTW
List of Figures
Figure 3.1 Proposed Water Quality Monitoring
Stations
Appendix
Appendix A Implementation
Schedule of Proposed Mitigation Measures
Appendix B Sample
Data sheets for Air and Water Quality Monitoring
Appendix E Indicative Requirements of the Post
Project Water Quality Monitoring Programme
3.1.1.1
Marine
water quality monitoring is recommended to be carried out during and after any
emergency discharge of untreated or partially treated effluent from the
upgraded PPSTW in the event of interruption of the
electrical power supply or failure of treatment units. A
framework of the emergency response has been formulated in this EM&A Manual
to minimize the impacts from the emergency discharge. Effluent quality from the upgraded PPSTW will
be governed by the Water Pollution Control Ordinance (WPCO) and the associated
discharge licence conditions after the Project is commissioned.
3.1.1.2
In
this section, the requirements, methodology, equipment, monitoring locations,
criteria and protocols for the monitoring and audit of water quality impacts
are presented.
Monitoring
Locations and Schedule
3.2.1.1
It is recommended to set up 11
monitoring stations as shown in Figure 3.1. The stations (B1 to B6, WSD1 to WSD2 and U2) represent
the sensitive receivers which could potentially be affected by the untreated or
partially treated effluent from the PPSTW. Stations NM1 and NM6 are located
outside the influence zone of the emergency discharge as predicted by the water
quality modelling and would unlikely be affected by the Project and will
therefore serve as control stations.
3.2.1.2
The coordinates of the proposed
monitoring stations are listed in Table
3.1.
Table
3.1 Proposed Water Quality Monitoring
Stations
|
Station
|
Description
|
Easting
|
Northing
|
|
B1
|
Butterfly Beach
|
813608.8
|
825772.6
|
|
B2
|
Castle Peak Beach
|
815931.5
|
826571.5
|
|
B3
|
Kadoorie Beach
|
816214.2
|
826202.8
|
|
B4
|
Cafeteria Old
Beach
|
816435.4
|
826055.3
|
|
B5
|
Cafeteria New Beach
|
815464.5
|
825330.2
|
|
B6
|
Golden Beach
|
812859.2
|
824359.3
|
|
WSD1
|
Flushing Water Intake near Butterfly Beach
|
813215.6
|
825477.7
|
|
WSD2
|
Flushing Water Intake near LRT
Terminus
|
815231.0
|
825797.2
|
|
U2
|
Secondary Contact
Recreation Subzone at Lung Kwu
Tan
|
809528.7
|
827566.9
|
|
NM6
|
Control Station
|
807599.3
|
820285.4
|
|
NM1
|
Control Station
|
820256.0
|
823213.8
|
3.2.1.3
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 11 stations
after commissioning of the Project.
During each monitoring event, water samples shall be collected at
different tidal status (one for high tide and one for low tide). The baseline water quality data shall be
reviewed together with the routine marine water quality data collected by EPD
at the North Western waters to establish the baseline water quality
conditions. The purpose of the baseline
monitoring is to establish ambient conditions when the Project is operated
normally. The baseline monitoring shall
be ceased in the events of any emergency discharges.
3.2.1.4
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.
3.2.1.5
During the operation phase of
the Project, in the event of emergency discharge of untreated or partially
treated effluent, daily marine water monitoring shall be conducted by the
Environmental Team at the 11 monitoring stations throughout the whole emergency
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 high tide and
low tide (i.e. twice a day).
3.2.1.6
The monitoring programme for such
emergency discharge event shall be conducted in the first year after
commissioning of the Project. After
1-year monitoring period, a review shall be conducted by the SOR to recommend
whether such monitoring shall be continued.
The review results shall be submitted to DSD prior to the submission to
EPD for approval. Termination or any
amendment to the monitoring programme shall be agreed by EPD.
3.2.1.7
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 DSD and EPD, before the
commencement of the monitoring. It is
recommended that the PPSTW operator should
monitor the quality (i.e. E.coli
level, pH value, temperature, salinity, turbidity and dissolved oxygen) and
quantity of sewage effluent discharged from the upgraded PPSTW during the
marine water sampling for data interpretation.
3.2.1.8
It is recommended that relevant
government departments including DSD, EPD, AFCD, WSD and LCSD shall be informed
of any emergency discharge events. The
PPSTW operator shall 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 PPSTW operator. A framework of the emergency response is
provided in Table 3.3.
Water
Quality Parameter
3.2.1.9
The E.coli levels shall be monitored and determined by laboratory.
Site
Records
3.2.1.10
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 Environmental Team Leader may modify the
data record sheet for this EM&A programme, of which the format should be
approved by DSD and agreed by the IEC and SOR.
Monitoring
Equipment
Dissolved Oxygen and Temperature Measuring
Equipment
3.2.1.11
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.
3.2.1.12
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).
3.2.1.13
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.
Turbidity Measurement Instrument
3.2.1.14
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.
Sampler
3.2.1.15
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).
Water Depth Detector
3.2.1.16
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.
Salinity
3.2.1.17
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.
pH
3.2.1.18
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.
Monitoring Position Equipment
3.2.1.19
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.
Calibration of In-Situ Instruments
3.2.1.20
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.
3.2.1.21
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.
Sample
Containers and Storage
3.2.1.22
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.
Laboratory
Measurement / Analysis
3.2.1.23
Analysis of E.coli levels shall be carried out in a
HOKLAS or other international accredited laboratory. The recommended analysis method is provided
in Table 3.2. The analysis shall
commence within 24 hours after collection of the water samples. The laboratory
shall be HOKLAS accredited for analysis of E.coli
in marine water. 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
DSD and the IEC for agreement and 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. Additional duplicate
samples may be required by EPD for inter laboratory calibration. Remaining
samples after analysis shall 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 shall have comprehensive quality assurance
and quality control programmes. The laboratory shall demonstrate the programmes
to EPD or his representatives when requested.
Table 3.2 Analytical
Method to be applied to Marine Water Quality Samples
|
Determinant
|
Suggested
Method
|
Suggested
Detection Limit
|
|
E.coli
|
EPD
HKSAR, Wat. Sci. Tech. Vol. 35, No. 11-12 pp 409-413
|
1 cfu per100mL
|
Emergency
Response
General Requirement
3.2.1.24
The PPSTW operator shall inform
DSD, EPD, WSD and LCSD in case of any emergency discharge of untreated or partially
treated effluent due to power supply failure or equipment failure in the
upgraded PPSTW. 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 PPSTW operator. The PPSTW operator
shall be responsible for carrying out marine water quality monitoring within 24
hours when the discharge event occurs.
The PPSTW operator shall closely liaise with relevant parties so that
the DSD, EPD, WSD and LCSD can be informed promptly of any cases of emergency
discharge. The event and action plan
under emergency discharge of treated or partially treated effluent are provided
in Table 3.3.
3.2.1.25
Under emergency discharge, it
is recommended that the PPSTW operator should
monitor daily quality (i.e. E.coli
level, pH value, temperature, salinity, turbidity and dissolved oxygen) and
quantity of sewage effluent discharged from the PPSTW during the whole water
quality monitoring period for data interpretation.
Table
3.3 Emergency Response Plan for
Discharge of
Untreated or Partially Treated Effluent from PPSTW
|
Event
|
Action
Plan
|
|
Failure of main treatment units due to power
supply failure or equipment failure
|
1. PPSTW operator to investigate
the reason of plant failure and to implement appropriate remedial measures as
stipulated in the contingency / operation plan for the PPSTW.
2. If emergency
discharge is required, Plant operator to inform DSD, EPD, WSD and LCSD within
1 hour after the discharge commence.
3. EPD / LCSD to take
immediate actions to prevent any bathing and water sports activities at the
beaches and secondary contact recreation subzones within the North Western
WCZ.
4. PPSTW operator to
instruct the Environmental Team to commence water monitoring within 24 hours
after the emergency discharge event occurs.
5. PPSTW operator 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.
6. DSD to ensure
appropriate remedial measures as stipulated in the contingency / operation
plan are implemented.
7. Environmental Team
to conduct daily marine water monitoring (as discussed in Section 3.2.1.24)
until the baseline water quality levels are restored or 7 days after the
emergency discharge is ceased, whichever is the shortest.
8. The IEC 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 DSD, EPD
and LCSD.
|
3.2.1.26
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 emergency discharge. For each emergency discharge event, a Water
Quality Monitoring Report shall be submitted to DSD, EPD and LCSD 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.
Construction
Site Audits
3.3.1.1
Implementation of regular site
audits is to ensure that the recommended mitigation measures are to be 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.
3.3.1.2
Site audits shall include site
inspections and compliance audits.
Site
Inspections
3.3.1.3
Site inspections 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 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 site management. Suitable 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
3.3.1.4
Compliance audits are to be undertaken
to ensure that a valid discharge license has been issued by EPD prior to the
discharge of effluent from the construction activities of the Project site. If monitoring of the treated effluent quality from
the Works Areas is required during the construction phase of the Project, the
monitoring should be carried out in accordance with the WPCO license which is
under the ambit of regional office (RO) of EPD. The audit results reflect
whether the effluent quality is in compliance with the discharge license
requirements. In case of non-compliance, suitable actions by the ET should be
undertaken to:
·
Notify the Contractor, IEC, SOR and DSD on 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.
3.4.1.1
A Post
Project Water Quality Monitoring (PPWQM) programme will be implemented to
confirm the predictions of the water quality made in the EIA report. The extent
of PPWQM programme is subject to the prevailing environmental conditions at the
time before commissioning of the Project. A conservative PPWQM programme is
proposed, which include one year baseline monitoring before commissioning and
one year impact monitoring after commissioning. The elements of the PPM
programme include monitoring of effluent quality, sediment quality, marine
water quality, benthic survey and ecotoxicological assessment. The PPWQM programme
is enclosed as Appendix E for
reference.
3.5.1.1
Mitigation measures for water
quality control have been recommended in the EIA Report and are listed in the
implementation schedule given in Appendix
A.