4.1 Water quality impact during operational phase will be minimized through implementation of the recommended mitigation measures. Water quality audit requirements will therefore cover the construction phase only.
4.2 It is the contractor’s responsibility to ensure that all wastewater or site runoff produced during the construction works for the Atrium Link Extension (ALE) are handled, stored and disposed of in accordance with good management practices and EPD’s regulations and requirements.
4.3
Marine water quality monitoring is also
recommended to be carried out at the cooling water intakes inside the ALE sea
channel. The monitoring should include baseline and impact monitoring. The
impact monitoring should be carried out during the installation period and removal
period of the temporary marine piles.
4.4 Implementation of regular site audits is also recommended 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. Site audits shall include site inspections and compliance audits.
Cooling Water Intake Monitoring Schedule and Stations
4.5
The proposed water quality monitoring
stations are shown in Table 4.1 and Figure 4.1. The monitoring stations
proposed in this section are indicative subject to further review before
construction phase. The status and locations of water sensitive receivers and
the marine activities may change after issuing this Manual. If such case exist,
the ET Leader shall propose updated monitoring locations and seek approval from
the IC(E) and EPD.
4.6 It is proposed to monitor the water quality at three cooling water intakes inside the ALE sea channel. Due to their close proximity to the construction activities, silt screens are recommended to be deployed at these intakes during the whole construction period. It is recommended to conduct the monitoring behind the silt screens and at the appropriate vertical levels of the abstraction points of these intakes to collect information on the mitigated water quality condition if practicable.
Table 4.1 Proposed Marine Water Quality Stations for Baseline and Construction Phase Monitoring
|
Station |
Description |
Easting |
Northing |
|
(3) |
|
835852.3 |
815907.0 |
|
(4) |
Wan |
835944.1 |
815885.0 |
|
(5) |
Great Eagle Centre, |
835963.4 |
815886.5 |
Baseline Monitoring
4.7 Baseline conditions for marine water quality should be established and agreed with EPD prior to the commencement of marine works. The purpose of the baseline monitoring is to establish ambient conditions prior to the commencement of the construction works and to demonstrate the suitability of the proposed monitoring stations.
4.8
The baseline conditions should be
established by measuring dissolved oxygen (DO), turbidity and suspended solids
(SS) levels at 3 selected monitoring stations as shown in Table 4.1. The baseline monitoring schedule should be submitted to
EPD at least 2 weeks before commencement of monitoring for agreement. EPD should also be notified immediately for
any changes in schedule.
4.9 The measurements 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 marine 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 measurements and water sampling should be carried out in each sampling event. For selection of tides for in-situ measurement and water sampling, tidal range of individual flood and ebb tides should be not less than 0.5 m.
4.10
The baseline monitoring report should be
submitted to EPD at least 4 weeks before the commencement of construction works
for agreement. The baseline monitoring
report should be certified by the IE(C) before submission to EPD.
Impact Monitoring
4.11
During the period of installation and removal of
temporary marine piles, monitoring should be undertaken three days per week, at
mid-flood and mid-ebb tides, with sampling/measurement at the designated
monitoring stations as shown in Table
4.1. 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 4.2 shows the proposed monitoring
frequency and water quality parameters. Duplicate in-situ measurements and water sampling should be carried out in
each sampling event. For selection of tides for in-situ measurement and water sampling, tidal range of individual
flood and ebb tides should be not less than 0.5 m.
Table 4.2 Proposed Marine Water Quality Monitoring Frequency and Parameters
|
Activities |
Monitoring Frequency Note 1 |
Key Parameters Note 2 |
|
During the 4-week baseline
monitoring period |
Three days per week, at mid-flood
and mid-ebb tides |
Dissolved Oxygen (DO), turbidity, Suspended Solids (SS) |
|
During installation and removal of
temporary marine piles |
Three days per week, at mid-flood
and mid-ebb tides |
Dissolved Oxygen (DO), turbidity, Suspended Solids (SS) |
Note:
1.
For selection of tides for in-situ measurement and water sampling,
tidal range of individual flood and ebb tides should be not less than 0.5 m.
2.
DO and turbidity should be
measured in situ whereas SS should be determined by laboratory.
4.12 The proposed water quality monitoring schedule should be passed to EPD at least 1 week before the first day of the monitoring. EPD should also be notified immediately for any changes in schedule. If the monitoring data collected at the cooling water intake indicate that the Action or Limit levels as shown in Table 4.5 are exceeded, appropriate actions should be taken to stop the marine works and mitigation measures such as slowing down the piling and pile extraction, or rescheduling of works should be implemented as necessary.
Construction Site Audits
4.13 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.
4.14
Site audits should include site
inspections and compliance audits.
Site Inspections
4.15 Site inspections should be carried out by the ET and should be based on the mitigation measures for water pollution control recommended in Appendix B. In the event that the recommended mitigation measures are not fully or properly implemented, deficiency should 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 which 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
4.16 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 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 should be undertaken to:
· notify the site management for 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.
4.17
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.
4.18
A sample
data record sheet is shown in Appendix A
for reference.
Dissolved Oxygen and Temperature
Measuring Equipment
4.19
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-1 and 0 ‑ 200% saturation; and
· a temperature of 0 ‑ 45 degree Celsius.
4.20 It should have a membrane electrode with automatic temperature compensation complete with a cable. Sufficient stocks of spare electrodes and cables should 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).
4.21 Should salinity compensation not be built-in to the DO equipment, in-situ salinity should be measured to calibrate the DO equipment prior to each DO measurement.
Turbidity Measurement Instrument
4.22 Turbidity should be measured in situ by the nephelometric method. The instrument should be portable and weatherproof using a DC power source complete with cable, sensor and comprehensive operation manuals. It should have a photoelectric sensor capable of measuring turbidity between 0 - 1000 NTU (for example, Hach model 2100P or an approved similar instrument). The cable should not be less than 25m in length. The meter should be calibrated in order to establish the relationship between NTU units and the levels of suspended solids. The turbidity measurement should be carried out on split water sample collected from the same depths of suspended solids samples.
Sampler
4.23 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).
Water Depth Detector
4.24 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.
Salinity
4.25
A
portable, salinometer capable of measuring salinity in the range 0 – 40 mg/L
shall be provided for measuring salinity of the water at each monitoring
location.
Sample Containers and Storage
4.26 Water samples for SS should be stored in high density polythene bottles, 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.
Monitoring Position Equipment
4.27 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, should be provided and used during water quality monitoring to ensure the monitoring vessel is at the correct location before taking measurements. DGPS or the equivalent instrument, calibrated at appropriate checkpoint (e.g. Quarry Bay Survey Nail at Easting 840683.49, Northing 816709.55) should be provided and used to ensure the monitoring station is at the correct position before taking measurement and water samples.
Calibration of In-Situ Instruments
4.28 All in-situ monitoring instruments should 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 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.
4.29 For the on site calibration of field equipment, the BS 127:1993, Guide to Field and On-Site Test Methods for the Analysis of Water should be observed.
4.30 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.
Laboratory Measurement / Analysis
4.31
Analysis of SS level should be carried out in a
HOKLAS or other international accredited laboratory. Sufficient water samples of not less than 1
liter should be collected at the monitoring stations for carrying out the
laboratory SS determinations. The
suggested testing method and lowest detection limit are provided in Table 4.3.
Table 4.3 Analytical Methods to be applied to Marine Water Quality Samples
|
Determinant |
Suggested Method |
Suggested Detection Limit |
|
Suspended solids |
APHA 2540D |
1 mg L-1 |
APHA American Public Health Association Standard
Methods for the Examination of Water and Wastewater
4.32 The testing of SS should be HOKLAS accredited (or if not, approved by the EPD) and comprehensive quality assurance and control procedures in place in order to ensure quality and consistency in results.
4.33 If a site laboratory is set up or a non-HOKLAS and non-international accredited laboratory is hired for carrying out the laboratory analysis, the laboratory equipment, analytical procedures and quality control should be approved by EPD. All of the analysis should be witnessed by the EPD,
4.34 The ET should provide the Contractor with on copy of the relevant chapters of the “Standard Methods for the Examination of Water and Wastewater” updated edition and any other relevant document for his reference.
4.35 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 should 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 should be in accordance with the requiremtn of HOKLAS or international accredited scheme. The QA/QC results should be reported. The testing methods and related proposal should be checked and certified by IC (E) before submission to EPD for approval.
4.36 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 programmes to EPD or his representatives when requested.
4.37
Operators of the three cooling water intakes
inside the ALE sea channel were consulted under this Study. Based on the information provided by the
intake operators, no specific requirement on the seawater quality is available
for all the 3 cooling water intakes. The water
quality assessment criteria, namely Action and Limit levels are shown in Table 4.4. Should the monitoring results of the water
quality parameters at any designated monitoring stations indicate that the
water quality assessment criteria are exceeded, the actions in accordance with
the Action Plan in Table 4.5 be
carried out.
4.38 The ET Leader should assess the potential construction phase impacts on the cooling intakes 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 4.4 Action and Limit Levels for Marine Water Quality at the Cooling Water Intakes
|
Parameters |
Action |
Limit |
|
|
DO in mg L-1 |
Cooling water intakes |
5 percentile of baseline data |
1 percentile of baseline data |
|
SS in mg L-1
|
Cooling water
intakes |
95
percentile of baseline data |
99
percentile of baseline data |
|
Turbidity
in NTU |
Cooling
water intakes |
95 percentile of baseline data |
99 percentile of baseline data |
Notes: 1. It is recommended to conduct the
monitoring behind the silt screens and at the appropriate vertical levels of
the abstraction points of these intakes
2.
For DO, non-compliance of the water
quality limits occurs when monitoring result is lower than the limits.
3.
For turbidity and SS, non-compliance
of the water quality limits occurs when monitoring result is higher than the
limits.
4.
All the figures given in the table
are used for reference only and the EPD may amend the figures whenever it is
considered as necessary.
4.39 Given the rather short duration for baseline data collection, it may not be viable to work out the percentile water quality. Where necessary, EPD routine marine water quality monitoring data at the relevant station(s), dry and wet seasons inclusive, could be referred. The ET should approach the Water Quality Assessment Section of EPD for the data.
Mitigation of
Adverse Environmental Impacts
4.40 Mitigation measure for water quality control have been recommended in the EIA Report. The Contractor should be responsible for the design and implementation of these measures.
4.41 Recommended mitigation measures to minimize the adverse impacts on water quality during construction phase are listed in the implementation schedule given in Appendix B.
Table 4.5 Event and Action Plan for Marine Water Quality
|
EVENT |
ACTION |
|||
|
|
ET |
IC(E) |
ER |
CONTRACTOR |
|
Action level being exceeded by one sampling
day |
Repeat in-situ measurement to confirm
findings; Identify source(s) of impact; Inform IC(E) and Contractor; Check monitoring data, all plant, equipment
and Contractor's working methods; Discuss mitigation measures with IC(E) and
Contractor; (The above actions should be taken within 1
working day after the exceedance is identified) 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. (The above actions should be taken within 1
working day after the exceedance is identified) |
Discuss with IC(E) on the proposed mitigation
measures; Make agreement on the mitigation measures to
be implemented. (The above actions should be taken within 1
working day after the exceedance is identified) |
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 IC(E) and propose
mitigation measures to IC(E) and ER; Implement the agreed mitigation measures. (The above actions should be taken within 1
working day after the exceedance is identified) |
|
Action level being exceeded by more than one consecutive sampling days |
Identify source(s) of impact; Inform IC(E) and Contractor; Check monitoring data, all plant, equipment
and Contractor's working methods; Discuss mitigation measures with IC(E) and
Contractor; Ensure mitigation measures are implemented; Prepare to increase the monitoring frequency
to daily; (The above actions should be taken within 1
working day after the exceedance is identified) Repeat measurement on next working 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. (The above actions should be taken within 1
working day after the exceedance is identified) |
Discuss with IC(E) on the proposed mitigation
measures; Make agreement on the mitigation measures to
be implemented; Assess the effectiveness of the implemented
mitigation measures. (The above actions should be taken within 1
working day after the exceedance is identified) |
Inform the Engineer 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 IC(E) and propose
mitigation measures to IC(E) and ER within 3 working days; Implement the agreed mitigation measures. (The
above actions should be taken within 1 working day after the exceedance is
identified) |
|
Limit level being exceeded by one sampling day |
Repeat in-situ measurement to confirm
findings; Identify source(s) of impact; Inform IC(E), contractor and EPD; Check monitoring data, all plant, equipment
and Contractor's working methods; Discuss mitigation measures with IC(E), ER and
Contractor; Ensure mitigation measures are implemented; Increase the monitoring frequency to daily
until noexceedance of Limit level. (The
above actions should be taken within 1 working day after the exceedance is
identified) |
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. (The above actions should be taken within 1
working day after the exceedance is identified) |
Discuss with IC(E), 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. (The above actions should be taken within 1
working day after the exceedance is identified) |
Inform the Engineer 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 , IC(E) and ER and propose
mitigation measures to IC(E) and ER within 3 working days; Implement the agreed mitigation measures. (The
above actions should be taken within 1 working day after the exceedance is
identified) |
|
Limit level being exceeded by more than one
consecutive sampling days |
Identify source(s) of impact; Inform IC(E), contractor and EPD; Check monitoring data, all plant, equipment
and Contractor's working methods; Discuss mitigation measures with IC(E), ER and
Contractor; Ensure mitigation measures are implemented; Increase the monitoring frequency to daily
until no exceedance of Limit level for two consecutive days. (The
above actions should be taken within 1 working day after the exceedance is
identified) |
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. (The above actions should be taken within 1
working day after the exceedance is identified) |
Discuss
with IC(E), 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 marine work until no exceedance of Limit level. (The
above actions should be taken within 1 working day after the exceedance is
identified) |
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 , IC(E) and ER and propose mitigation measures to IC(E) and ER within
3working days; Implement
the agreed mitigation measures; As
directed by the Engineer, to slow down or to stop all or part of the marine
work or construction activities. (The
above actions should be taken within 1 working day after the exceedance is
identified) |