5.4.1 Dissolved Oxygen and Temperature Measuring Equipment
5.4.2 Turbidity Measurement Instrument
5.4.7 Sample Containers and Storage
5.4.8 Monitoring Position Equipment
5.4.9 Calibration of In-Situ Instruments
5.4.10 Back-up Equipment and Vessels
5.5 Laboratory Measurement / Analysis
5.7 Baseline Monitoring for Water Quality
5.8 Efficiency of Silt Curtains
5.9 Impact Monitoring for Water Quality
5.9.2 Relocation of Mf Sediment with Reclamation Area
5.9.3 Water Quality Monitoring along the Water Boundary of Hong Kong and Mainland
5.10 Post-construction Monitoring
5.11 Operational Phase Monitoring
5.1.1.1 Since the marine works of TM-CLKL will be concurrent with HKBCF and HKLR and the southern landfall of TM-CLKL is indeed an integrated part of the HKBCF The potential water quality impacts of TM-CLKL has been assessed jointly with HKBCF and HKLR. The EIA has, therefore, recommended that the water quality monitoring works of the three concurrent projects, also by the same project proponent, be conducted as a whole to enhance the efficiency and cost-effectiveness of the monitoring programme. Based on this, the water quality monitoring scheme designed assuming the monitoring will be implemented jointly and be coordinated with a project ENPO office.
5.2.1.1 The reclamation layout of TM-CLKL, HKBCF and HKLR are presented in Figures 5.1 to 5.4. For HKBCF+TM-CLKL southern landfall, the layout of the two alternate construction sequences are presented in Figure 5.2 (Sequence A) and Figure 5.3 (Sequence B). The overall combined maximum daily production rates, the maximum number of plant (dredging and filling) trips and the number of active plants (dredging and filling) on sites for marine works below +2.5mPD are summarised in Figure 5.5a, 5.5b and 5.5c for Sequence A. The corresponding summaries for Sequence B are presented in Figure 5.6a, 5.6b and 5.6c, respectively. The EIA Report has assessed the water quality impacts caused by the construction and operation stages. Mitigation measures have been recommended in the EIA to ensure compliance with the relevant legislative requirements. These mitigation measures are summarised below.
· Closed grabs should be used for sediment dredging to reduce sediment loss when lifting the grabs to the barges.
· The decks of dredging barges should be clean and tidy to avoid any sediment to be washed into the sea.
· Loading of the dredged sediments to the barges should be carried out carefully to minimise splashing of sediments.
· Overloading of barge is not allowed and sufficient freeboard should be maintained to ensure no spill over of the dredged sediments during lifting and transport.
· The moving speed of construction vessels in the dredging area should be reduced to prevent disturbance to the seabed generating sediment plumes.
· A cage type silt curtain is proposed to be installed to enclose local pollution caused by the grab dredging. The grab dredging work should be carried out within the cage type silt curtain. Apart from the cage type silt curtain, it is recommended to deploy a floating type silt curtain around the site. Silt curtains can be effectively applied when the current speeds are lower than 0.5 m/s. The velocity of current near the northern edge of reclamation site of HKBCF Phase 2 / TM-CLKL southern landfall is higher than 0.5 m/s, thus a sheet pile wall is proposed to protect the silt curtain along the northern edge. The proposed floating type silt curtain would be installed within the site area of TM-CLKL southern landfall, near shore section of TM-CLKL northern landfall (portion N-a), HKBCF and HKLR as far as practicable. For construction Sequence B, specially designed cage type silt curtain (with steel enclosure) is also proposed for the grab dredging at HKBCF and TM-CLKL southern landfall where localised flow can reach 0.5 m/s. The typical arrangement of the silt curtains are shown in Figures 25308/041/307, 308a and 309 of Annex A.
· Pilot tests should be carried out during the early stage of seawall construction to confirm whether the silt removal efficiency of the cage type silt curtain and the floating type silt curtain can respectively achieve 80% and 45% silt removal efficiency for dredging and filling activities when deployed separately, and a combined reduction of 95% and 61% when the two type of silt curtains are used jointly. Pilot tests for cage type silt curtain (with steel enclosure) should be carried out in a similar time frame should Sequence B be implemented to see if the cage type silt curtain (with steel enclosure) can achieve 80% reduction when applied singly under current above 0.5 m/s.
· The pilot tests shall be conducted during the initial months of dredging and filling works of either TM-CLKL, HKBCF or HKLR The silt-removal efficiency of the silt curtains shall be verified by examining the results of water quality monitoring points. The water quality monitoring points to be selected for the above shall be those close to the locations of the initial period of dredging work. Details of this pilot study shall be determined by the ENPO and agreed by EPD before the commencement of the monitoring, taking account of the Contractor’s proposed actual locations of his initial period of dredging work. ET shall submit the pilot test proposal detailing the layout of silt curtains, monitoring location and testing arrangement for EPD’s agreement before conducting the pilot tests.
· A sheet piled wall shall be constructed to the north of the TM-CLKL southern landfall / HKBCF island, and also in the main HKBCF reclamation in order to allow the use of silt curtains during Phase 2 works before the re-deposition the Mf materials;
· Figures 25308/041/301 to 304 of Annex A illustrates different stages of the arrangement of silt curtains and shows the typical seawall sections of Sequence A, and that for Sequence B are presented in Figures 25308/041/301A to 304A of Annex A. The hanging-type silt curtain should allow access of vessels to enter into or exit from the reclamation area. The vessel access opening would be formed by two piece of silt curtain with overlapping length of 150m minimum and a separation distance of about 50m. The indicative position and details of the above openings for HKBCF and HKLR are also shown in these figures;
· The dredging and filling works shall be scheduled to spread the works evenly over a working day; and
· The silt curtains should be maintained in good condition to ensure the sediment plume generated from dredging and filling be confined effectively within the site boundary.
5.2.1.2 Prior to the commencement of the construction work, a detailed site drainage management plan should be submitted to EPD. The plan should cover measures to minimize all potential water quality impact arising from the surface runoffs of all the related constructions.
5.2.1.3 The guidelines outlined in the Practice Note for Professional Persons (ProPECC), Construction Site Drainage (PN 1/94) should be adopted to control construction site runoff. Mitigation measures to minimise water quality impacts from construction site runoff and wastewater and sewage generated from construction activities are:
· Provision of site drainage systems over the entire construction site with sediment control facilities. Regular inspection and maintenance of the site drainage systems are required to ensure proper and efficient operation at all times.
· Sedimentation tanks or package treatment systems are required to treat the large amount of sediment-laden wastewater generated from foundation construction work, wheel washing, site runoff. Any construction activities that generate wastewater with high concentrations of SS should also be collected to these facilities for proper treatment prior to disposal. Treated wastewater can be reused for vehicle washing, dust suppression and general cleaning. Bentonite slurry used in bore-pile construction should be reconditioned and reused to minimise the disposal volume of the used slurry.
· The construction programme should be properly planned to avoid soil excavation in rainy seasons. Exposed stockpiles of excavated soils or construction materials should be covered with tarpaulin or impervious sheets to avoid release of pollutants into the drainage channels.
· Sewage generated from site toilets and canteen should be collected using a temporary storage system. Chemical toilets should be provided at different locations for use by the workers on site. Licensed waste collectors should be employed for collection and disposal of the sewage. The drainage system for collection of wastewater generated from canteen, if any, should be equipped with grease trap capable of providing at least 20 minutes retention during peak flow.
· Wheel washing facilities should be installed at all site entrances/exits.
· An emergency plan should be developed by the contractors to deal with accidental spillage of chemicals.
5.2.1.4 Upon completion of the TM-CLKL / HKLR / HKBCF development, stormwater drainage systems would be completed to collect stormwater generated from the whole area including new roads. Sewage generated from the TM-CLKL southern landfall and HKBCF development would be treated on site to fulfill effluent limit for discharge. Additional mitigation measures would not be required.
5.2.1.5 As identified in the EIA Report, key water quality issues during construction phase will be dredging and filling works for the reclamation, backfilling of Mf sediment within the reclamation sites (handing of Mf sediment is not predicted for TM-CLKL, but HKBCF and HKLR would require handing of Mf sediment and the proposed locations are shown in Figures 5.9 and 5.10) and TSHD dredging overflow process for the construction of artificial islands within the mainland water boundary but so close to Hong Kong. Marine water quality monitoring shall be carried out during the construction phase to ensure that any unacceptable increase in suspended solids / turbidity and decrease in dissolved oxygen due to dredging and filling activities could be readily detected and timely action be taken to rectify the situation.
5.2.1.6 The EIA Report has recommended construction and operational phase mitigation measures. All the prepared mitigation measures are summarised in the Environmental Mitigation Implementation Schedules in Appendix A.
5.3.1.1 As identified in the EIA Report, key water quality issues during construction phase will be dredging and filling works for the reclamation. Marine water quality monitoring shall be carried out during the construction phase to ensure that any unacceptable increase in suspended solids / turbidity and decrease in dissolved oxygen due to dredging and filling activities could be readily detected and timely action be taken to rectify the situation.
5.3.1.2 In addition to dissolved oxygen (DO), turbidity (NTU), suspended solids (SS) levels and other general in-situ parameters to be monitored at all designated marine water quality monitoring stations during the whole construction phase, nutrients and heavy metal parameters shall also be measured at selected relevant locations during the baseline, backfilling of Mf sediment and post construction period. DO and turbidity should be measured in-situ whereas SS, nutrients and heavy metals should be determined by an accredited laboratory.
5.3.1.3 Other relevant data shall also be recorded in a Water Quality Monitoring Logs, including monitoring location / position, time, water depth, pH value, salinity, temperature, tidal stages, weather conditions and any special phenomena or work underway at the construction site. A sample monitoring record sheet is shown in Figure 5.7.
5.3.1.4 According to the EIA report, there is low concentration for PAH, PCB, TBT, and chlorinated pesticides. Monitoring of these chemicals would not be required during the construction stage.
5.3.1.5 The proposed water quality monitoring schedule shall be submitted to EPD at least 2 weeks before the first day of the monitoring month. EPD shall also be notified immediately for any changes in schedule by fax.
5.3.1.6
For TM-CLKL southern viaducts,
surveys of the watercourse NL1 in
5.4.1.1 The instrument should be a portable and weatherproof dissolved oxygen (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.
5.4.1.2 It should have a membrane electrode with automatic temperature compensation complete with a cable.
5.4.1.3 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.
5.4.2.1 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).
5.4.3.1 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).
5.4.4.1 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.
5.4.5.1 A portable salinometer capable of measuring salinity in the range of 0 - 40 parts per thousand (ppt) should be provided for measuring salinity of the water at each monitoring location.
5.4.6.1 A portable pH meter capable of measuring a range between 0.0 and 14.0 shall be provided to measure pH under the specified conditions (e.g., Orion Model 250A or an approved similar instrument).
5.4.7.1 Water samples for SS, nutrient and heavy metals determinations should be stored in high density polythene bottles, packed in ice (cooled to 4°C without being frozen) and keep in dark during both on-site temporary storage and shipment to the testing laboratory. The samples shall be delivered to the laboratory within 24 hours of collection and be analysed as soon as possible after collection.
5.4.8.1 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 instrument of similar accuracy, should be provided and used during marine water monitoring to ensure the monitoring vessel is at the correct location before taking measurements.
5.4.9.1 The pH meter, DO meter and turbidimeter shall be checked and calibrated before use. DO meter and turbidimeter shall be certified by a laboratory accredited under HOKLAS or any other international accreditation scheme, and subsequently re-calibrated at 3 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 shall be carried out before measurement at each monitoring location.
5.4.10.1 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. For the on site calibration of field equipment, the BS127:1993, "Guide to Field and on-site test methods for the analysis of waters" shall be observed.
5.4.10.2 The Water Quality Monitoring will involve a large number of monitoring stations and measurements should be conducted within the prescribed tidal conditions (within ± 1.75 hour of the predicted mid-ebb or mid-flood tides) in order to ensure the measurement/samples are representative. A multi-probe monitoring equipment set integrated with water sampler(s) is highly recommended to improve the monitoring efficiency. It is, also, likely that more than one field survey vessels will be required simultaneously to ensure the monitoring are conducted within the acceptable monitoring windows. The ET shall also consider the use of unattended automatic sampling/monitoring devices at fixed stations where monitoring are required throughout the construction period. The use of such unattended automatic devices, however, shall be subject to the approval of the ER, IEC and EPD.
5.5.1.1 Duplicate samples from each independent sampling event are required for all the suspended solids, nutrient and heavy metals measurement, which shall be carried in a HOKLAS or other international accredited laboratory. Sufficient water samples shall be collected at the monitoring stations for carrying out the laboratory measurement and analysis. The laboratory determination work shall start within 24 hours after collection of the water samples. The analysis for SS, nutrient and heavy metals are summarized in Table 5.1.
Table 5.1 Laboratory analysis for SS, nutrient and heavy metals
|
Parameters |
Instrumentation |
Analytical
Method |
Reporting Limit |
|
Suspended Solid (SS) |
Weighting |
APHA 2540-D |
0.1mg/L |
|
Nutrient |
|
|
|
|
Ammonia as N (NH4-N) |
FIA |
APHA 4500-NH3 H |
0.025mg/L |
|
Unionised ammonia (NH3)[1] |
By calculation |
By calculation |
By calculation |
|
Nitrite as N |
FIA |
APHA 4500-NO3 I |
0.025mg/L |
|
Nitrate as N |
FIA |
APHA 4500-NO3 I |
0.025mg/L |
|
TKN as N |
Titration |
APHA 4500-Norg + NH3 H |
1mg/L |
|
Total Phosphorus |
Colorimetric |
APHA 4500-P B&E |
0.1 mg/L |
|
Reactive Phosphorus |
FIA |
APHA 4500-P G |
0.1mg/L |
|
Heavy Metals |
|
|
|
|
Cadmium (Cd) |
ICP-MS |
USEPA 6020A |
0.2 µg/L |
|
Chromium (Cr) |
ICP-MS |
USEPA 6020A |
1 µg/L |
|
Copper (Cu) |
ICP-MS |
USEPA 6020A |
1 µg/L |
|
Mercury (Hg) |
ICP-MS |
USEPA 6020A |
0.1 µg/L |
|
Nickel (Ni) |
ICP-MS |
USEPA 6020A |
1 µg/L |
|
Lead (Pb) |
ICP-MS |
USEPA 6020A |
1 µg/L |
|
Silver (Ag) |
ICP-MS |
USEPA 6020A |
1 µg/L |
|
Zinc (Zn) |
ICP-MS |
USEPA 6020A |
4 µg/L |
|
Arsenic (As) |
ICP-MS |
USEPA 6020A |
10 µg/L |
Note [1]: By calculation based on the laboratory result of ammonia nitrogen (NH4-N) and in-situ measured pH, salinity and temperature.
5.5.1.2 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 shall be approved by sEPD. All the analysis shall be witnessed by the ER. The ET Leader shall provide the ER with one copy of the relevant chapters of the “APHA Standard Methods for the Examination of Water and Wastewater” 19th edition and any other relevant document for his reference.
5.6.1.1 The water quality monitoring stations, control stations and locations for during the construction and operation phases of HKBCF, TMCLKL and HKLR are shown in Figure 5.8. The demarcation of the monitoring stations for different projects will be further determined by the ENPO before the commencement of the construction. The selection of these stations are based on the following criteria:
(i) Impact stations (IS) within 250m – 500m envelope of the construction works and within the Mf sediment backfilling sites (i.e., 20 impact locations).
(ii) Sensitive receiver (SR) stations near to key sensitive receivers (i.e.10 impact stations).
(iii) Control / Far Field (CS) stations at representative locations with less influence by the projects (i.e.6 Control / Far Field stations). Control / Far Field stations should be located, as far as practicable, both upstream and downstream of the works area. The locations CS(Mf) also serve as the control stations for Mf deposition sites.
(iv) Stations for sensitivity test (ST) result, which are located close to the HKSAR boundary (i.e., 3 sensitivity test stations).
(iv) Impact stations (IS(Mf)) around the on-site Mf deposition sites during the on-site disposal of Mf material.
5.6.1.2 The co-ordinates of the proposed monitoring stations during construction, post-construction and operation phases are listed in Tables 5.2a and 5.2b and their distribution shown in Figure 5.8. As shown in Figure 5.8, the proposed locations for the sensitive receiver monitoring stations represent the typical sensitive receivers around the project works.
Table 5.2a Proposed Water Quality Monitoring Stations (Construction and Post-construction Phases)
|
Station |
Description |
East |
North |
Parameters to be measured |
|
IS1 |
Impact Station (Close to HKLR construction site) |
803474 |
815060 |
DO, Turbidity, SS |
|
IS2 |
Impact Station (Close to HKLR construction site) |
804851 |
815715 |
DO, Turbidity, SS |
|
IS3 |
Impact Station (Close to HKLR construction site) |
806502 |
815743 |
DO, Turbidity, SS |
|
IS4 |
Impact Station (Close to HKLR construction site) |
807008 |
816986 |
DO, Turbidity, SS |
|
IS5 |
Impact Station (Close to HKLR construction site) |
811579 |
817106 |
DO, Turbidity, SS |
|
IS(Mf)6 [1] |
Impact Station (Close to HKLR construction site) |
812101 |
817873 |
DO, Turbidity, SS, nutrient, heavy metals |
|
IS7 |
Impact Station (Close to HKBCF construction site) |
812244 |
818777 |
DO, Turbidity, SS |
|
IS8 |
Impact Station (Close to HKBCF construction site) |
814251 |
818412 |
DO, Turbidity, SS |
|
|
|
|
|
|
|
IS(Mf)9 [1] |
Impact Station (Close to HKBCF construction site) |
813273 |
818850 |
DO, Turbidity, SS, nutrient, heavy metals |
|
IS10 |
Impact Station (Close to HKBCF construction site) |
812577 |
820670 |
DO, Turbidity, SS |
|
IS(Mf)11 [1] |
Impact Station (Close to HKBCF construction site) |
813562 |
820716 |
DO, Turbidity, SS, nutrient, heavy metals |
|
IS12 |
Impact Station (Close to TMCLKL construction site) |
813218 |
823681 |
DO, Turbidity, SS |
|
IS13 |
Impact Station (Close to TMCLKL construction site) |
813667 |
824325 |
DO, Turbidity, SS |
|
IS14 |
Impact Station (Close to TMCLK construction site) |
812592 |
824172 |
DO, Turbidity, SS |
|
IS15 |
Impact Station (Close to TMCLK construction site) |
813356 |
825008 |
DO, Turbidity, SS |
|
IS(Mf)16 [1] |
Impact Station (Close to HKBCF construction site) |
814328 |
819497 |
DO, Turbidity, SS, nutrient, heavy metals |
|
IS17 |
Impact Station (Close to HKBCF construction site) |
814539 |
820391 |
DO, Turbidity, SS |
|
IS(Mf)18 [1] |
Impact Station (Close to the Marine Fill – for reference only) |
813564 |
820069 |
DO, Turbidity, SS, nutrient, heavy metals |
|
IS(Mf)19 [1] |
Impact Station (Close to the Marine Fill – for reference only) |
813564 |
819620 |
DO, Turbidity, SS, nutrient, heavy metals |
|
IS(Mf)20 [1] |
Impact Station (Close to the Marine Fill – for reference only) |
811650 |
818097 |
DO, Turbidity, SS, nutrient, heavy metals |
|
SR1 |
Sensitive
receiver |
803126 |
812379 |
DO, Turbidity, SS |
|
SR2 |
Sensitive
receiver |
807856 |
816953 |
DO, Turbidity, SS |
|
SR3 |
Sensitive
receiver |
810525 |
816456 |
DO, Turbidity, SS |
|
SR4 |
Sensitive
receiver |
814760 |
817867 |
DO, Turbidity, SS |
|
SR5 |
Sensitive receiver (Artificial Reef in NE Airport) |
811489 |
820455 |
DO, Turbidity, SS |
|
SR6 |
Sensitive
receiver (Sha Chau and |
805837 |
821818 |
DO, Turbidity, SS |
|
SR7 |
Sensitive
receiver |
814293 |
821431 |
DO, Turbidity, SS |
|
SR8 |
Sensitive receiver (Gazettal beaches in Tuen Mun) |
816306 |
825715 |
DO, Turbidity, SS |
|
SR9 |
Sensitive
receiver |
813601 |
825858 |
DO, Turbidity, SS |
|
SR10 |
Sensitive
receiver |
823741 |
823495 |
DO, Turbidity, SS |
|
CS1 |
Control Station |
801784 |
812711 |
DO, Turbidity, SS |
|
CS2 |
Control Station |
805849 |
818780 |
DO, Turbidity, SS |
|
CS(Mf)3 [1] |
Control Station |
809989 |
821117 |
DO, Turbidity, SS |
|
CS4 |
Control Station |
810025 |
824004 |
DO, Turbidity, SS |
|
CS(Mf)5 [1] |
Control Station |
817990 |
821129 |
DO, Turbidity, SS |
|
CS6 |
Control Station |
817028 |
823992 |
DO, Turbidity, SS |
|
ST1 |
Locations for
sensitivity test result (Close to Sha Chau and |
802677 |
816006 |
DO, Turbidity, SS |
|
ST2 |
Locations for sensitivity test result (Close to Chinese White Dolphin area near HKSAR boundary) |
804055 |
818840 |
DO, Turbidity, SS |
|
ST3 |
Locations for sensitivity test result (Close to Chinese White Dolphin area near HKSAR boundary) |
800667 |
810126 |
DO, Turbidity, SS |
Note [1]: During the construction phase, the nutrients and metals parameters only have to be measured during Mf sediment backfilling. After the pit for Mf sediment is backfilled and capped for one month, monitoring at IS(Mf)18, IS(Mf)19 and IS(Mf)20 locations can be stopped. The contractor should submit a detailed programme for agreement with EPD.
Table 5.2b Proposed Water Quality Monitoring Stations (Operation Phase)
|
Station |
Description |
East |
North |
Parameters to be measured |
|
SR3 |
Sensitive receivers (San Tau Beach SSSI) |
810525 |
816456 |
DO, Turbidity, SS, pH, salinity, temperature |
|
SR4 |
Sensitive receivers (Tai Ho Inlet) |
814760 |
817867 |
DO, Turbidity, SS, pH, salinity, temperature |
|
CS2 |
Control Station |
805849 |
818780 |
DO, Turbidity, SS, pH, salinity, temperature |
|
CS(Mf)5 |
Control Station |
817990 |
821129 |
DO, Turbidity, SS, pH, salinity, temperature |
5.6.1.3 Control stations ( CS1, CS2, CS(Mf)3, CS4, CS(Mf)5 and CS6) are necessary to compare the water quality from potentially impacted sites with the ambient water quality. Control stations shall be located within the same body of water as the impact monitoring stations but should be outside the area of influence of the works and, as far as practicable, not affected by any other works. The Control stations shown in Figure 5.8 are indicative subject to further review before construction phase. During the review, the location of the Impact stations for boundary of mixing zones will also be re-visited. If there are any changes to the monitoring locations, these shall be submitted 4 weeks before commencement of baseline monitoring for EPD approval.
5.6.1.4 In-situ monitoring (DO, temperature, turbidity, pH, salinity) and water sample for SS, nutrients and heavy metals shall be taken at 3 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. Should the water depth be less than 3 m, only the mid-depth station will be monitored. No marine construction activities should be conducted in the vicinity of the stations during the Baseline Monitoring period. The status and locations of water sensitive receivers and the marine activities may change after issuing this Manual. If such cases exist, the ET Leader shall propose with justification for changes to monitoring locations or other requirements of the EM&A programme, and seek approval from the IEC and EPD.
5.6.1.5 The ENPO may, depending on site conditions and monitoring results, decides whether additional monitoring locations shall be included or any monitoring locations could be removed/relocated during any stage of the construction phase, after getting approval from EPD.
5.7.1.1 Baseline conditions for marine water quality shall be established and agreed with EPD prior to the commencement of 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 impact and control monitoring stations. The baseline conditions shall normally be established by measuring the DO, temperature, turbidity, pH, salinity and SS at all designated locations, plus nutrients and heavy metals parameters at “Mf” locations specified in Section 5.6 above. The measurements shall be taken at all designated monitoring stations including control stations, 3 days per week, at mid-flood (within ± 1.75 hour of the predicted time) and mid-ebb (within ± 1.75 hour of the predicted time) tides, for at least 4 weeks prior to the commencement of marine works. Replicate in-situ measurements and samples collected from each independent sampling event shall be collected to ensure a robust statistically interpretable database.
5.7.1.2 Baseline monitoring programme may overlap with other reclamation activities. The monitoring exercise should be scheduled as far as possible to avoid concurrent dredging / backfilling activities around the monitoring stations such that representative ambient data could be sampled.
5.7.1.3 Other relevant data shall also be recorded, such as monitoring location / position, time, water depth, tidal stages, weather conditions and any special phenomena underway near the monitoring station. There shall not be any marine construction activities in the vicinity of the stations during the baseline monitoring.
5.7.1.4
As this project will last for
a few years, the ET Leader should seek approval from the IEC and EPD on an
appropriate set of data to be used with the baseline data collected by this
study to establish two set of
5.7.1.5 Baseline monitoring schedule shall be faxed to EPD 2 weeks prior to the commencement of baseline monitoring. The interval between two sets of monitoring shall not be less than 36 hours.
5.8.1.1 The ET shall be responsible for conducting tests to confirm that their silt curtain systems to be adopted would satisfy the requirements in the EIA Report.
5.8.1.2 Pilot tests should be carried out during the early stage of construction to confirm whether the silt removal efficiency of the cage type silt curtain and the floating type silt curtains can achieve 80% and 45% silt removal efficiency for dredging and filling activities respectively when deployed separately, and a combined reduction of 95% and 61% when the two type of silt curtains are used jointly. Pilot tests for cage type silt curtain (with steel enclosure) should be carried out in a similar time frame should Sequence B be implemented to see if the cage type silt curtain (with steel enclosure) can achieve 80% reduction when applied singly under current above 0.5 m/s.
5.8.1.3 The pilot test shall include basic measurements such as turbidity and suspended solids as well as current speed and direction. Where testing of cage type silt curtain (with steel enclosure) to is to be conducted at relatively fast current, supplementary Acoustic Doppler Current Profiler (ADCP) measurement of the plumes shall be considered to provide a better characterization of instant suspended solids plumes. A method statement shall be submitted by the ET Leader to seek approval from the IEC and EPD.
5.8.1.4 Cage type silt curtains will be applied round all grab dredgers during the HKBCF, HKLR and TM-CLKL southern reclamation works. Cage type silt curtain (with steel enclosure) shall be used for grab dredgers working in the site of HKBCF and TM-CLKL southern reclamation.
5.8.1.5 The pilot tests shall be conducted during the initial period of dredging and filling works of either TM-CLKL, HKBCF or HKLR. The silt-removal efficiency of the silt curtains shall be verified by examining the results of water quality monitoring points. The water quality monitoring points to be selected for the above shall be those close to the locations of the initial period of dredging work. The details for the pilot study shall be determined by the ENPO and agreed with EPD, taking account of the Contractor’s proposed actual locations of his initial period of dredging work. ET shall submit the pilot test proposal detailing the layout of silt curtains, monitoring location and testing arrangement for EPD’s agreement before conducting the pilot tests.
5.8.1.6 Regardless of the measured efficiency of the silt curtain system, the event and action plan shall only be based on the monitoring results at the designed monitoring stations.
5.9.1.1 Reclamation would require dredging and filling activities during the construction. During this period, silt curtains would be installed enclosing the whole project site to control sediment loss. Figures 25308/041/301 to 304 and 25308/041/301A to 304A of Annex A shows the arrangement of the silt curtains for Sequence A and Sequence B, respectively. During the construction period, monitoring shall be undertaken 3 days per week, at mid-flood (within ± 1.75 hour of the predicted time) and mid-ebb (within ± 1.75 hour of the predicted time) tides, with sampling / measurement at the designated monitoring stations. Replicate in-situ measurements and samples collected from each independent sampling event shall be collected to ensure a robust statistically interpretable database. The interval between two sets of monitoring shall 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. Two consecutive measures of DO concentration, DO saturation, pH, salinity, temperature, turbidity and water samples for SS, nutrients and heavy metals will be taken in situ at 1 m below the surface, mid-depth and 1 m above the seabed at each location. If the water depth is less than 6 m, the mid-depth measurement may be omitted subject to the approval of the ER. If the depth is less than 3 m, only the mid-depth measurements need to be taken subject to the approval of the ER. The monitoring probes shall 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 or turbidity parameters is more than 25% of the value of the first reading, the reading shall be discarded and further readings shall be taken.
5.9.1.2 For the construction phase, the nutrients and metal parameters only have to be measured at the locations with "Mf" during period of Mf sediment backfilling. After the pit for Mf sediment is backfilled and capped for one month, monitoring at IS(Mf)18, IS9(Mf)19 and IS(Mf)20 locations can be stopped.
5.9.1.3 If the Impact Monitoring results indicate that dredging / filling works have caused adverse impacts on water quality at the monitoring stations, appropriate actions (including the lowering of production rates for dredging and filling) should be taken and additional mitigation measures should be implemented as necessary. Under this circumstance, water quality monitoring frequency has to be increased to once per day when dredging / filling is undertaken. 24-hour monitoring of turbidity should be implemented as and when necessary. The monitoring results should be made available within a reasonable short period to be agreed with the EPD, ER and IEC.
5.9.2.1 The preliminary ground investigation conducted for TM-CLKL did not detected Mf material (ie. Category M Sediment which fails the biological test as per ETWB TC 34/2002) in the project site and no handling of Mf has been predicted. Therefore, this sub-section is only relevant to HKBCF and HKLR projects.
5.9.2.2 According to the current design of HKBCF/HKLR, the Mf sediment (ie. Category M Sediment which fails the biological test as per ETWB TC 34/2002) within the dredging area would be relocated to an area within the reclamation area. During this process, the ET is required to conduct near-field water quality measurements to ensure that the criteria for various water pollutants would be compiled. The monitoring shall be undertaken 3 days per week, at mid-flood (within ± 1.75 hour of the predicted time) and mid-ebb (within ± 1.75 hour of the predicted time) tides, with sampling / measurement at the designated monitoring stations to be agreed with EPD.
5.9.2.3 Before the commencement of the monitoring, the ET shall submit a proposal to EPD for agreement on the measurement methodology, locations, durations, parameters, detection limits, action and limit levels etc. The proposal shall be vetted by the IEC before submission to EPD for agreement. Key pollutant groups to be measured including SS, nutrients and heavy metals as summarised in Table 5.2. For the construction phase, the nutrients and metal parameters only have to be measured at the locations with "Mf" during period of Mf sediment backfilling. After the pit for Mf sediment is backfilled and capped for one month, monitoring at IS(Mf)18, IS9(Mf)19 and IS(Mf)20 locations can be stopped.
5.9.3.1 Stations for sensitivity test result shall be provided along the HKSAR Boundary to identify and assess any cross-boundary cumulative water quality impacts in order to establish suitable remedial actions where necessary.
5.10.1.1 Upon completion of all marine-based construction activities, a post-project monitoring exercise on water quality shall be carried out for 4 weeks in the same manner as the Baseline Monitoring. Replicate in-situ measurements and samples collected from each independent sampling event shall be collected to ensure a robust statistically interpretable database. The measurement parameters for Post-construction monitoring shall include DO, temperature, turbidity, pH, salinity and SS. The measurement shall be taken at all designated monitoring stations including control stations, 3 days per week, at mid-flood (within ± 1.75 hour of the predicted time) and mid-ebb (within ± 1.75 hour of the predicted time) tides, for at least 4 weeks. In addition, nutrient and metals should be monitored at the “Mf” locations up until one month after the pits have been capped.
5.10.1.2 Since the southern and northern landfalls of TM-CLKL are distant from each other and based on the tentatively programme available during the EIA stage the two landfall has a different construction time frame, the Post-construction monitoring for each landfalls may conducted separately. The ET should review the actual implantation programme and recommend if a separate post-construction monitoring for each landfall is required.
5.11.1.1 The marine water quality monitoring shall be performed monthly during the first year of Project operation at all designated monitoring stations including control stations. Each monthly monitoring event shall consist of one monitoring and sampling event during both mid-ebb (within ± 1.75 hour of the predicted time) and mid-flood (within ± 1.75 hour of the predicted time) tides of the same monitoring day.. The operation phase monitoring shall be ceased after the first year of operation of the Project subject to the first year review. No marine construction activities should be conducted in the vicinity of the stations during the Operational Phase monitoring period.
5.11.1.2 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. If the water depth be less than 3m, only the mid-depth station will be monitored. In-situ measurements at DO, turbidity, SS, pH, salinity and temperature shall be taken at all the monitoring stations SR2, SR3, CS2 and CS(Mf)5 (refer to Table 5.2b). A full set of in duplicated situ measurement and water samples shall be collected during each of the mid-ebb (within ± 1.75 hour of the predicted time) and mid-flood (within ± 1.75 hour of the predicted time) tides.
5.12.1.1 The Action and Limit levels for water quality are defined in Table 5.3. Should non-compliance of the criteria occur, action in accordance with the Action Plan in Table 5.4 shall be carried out.
Table 5.3 Action and Limit Levels for Water Quality
|
Parameters |
Action |
Limit |
|
DO in mg L-1 (Surface, Middle & Bottom) |
Surface and Middle 5 percentile of baseline data for surface and middle layer
Bottom 5 percentile of baseline data for bottom layer |
Surface and Middle 4 mg L-1 except 5 mg/l for FCZ or 1%-ile of baseline data for surface and middle layer Bottom 2 mg L-1 or 1%-ile of baseline data for bottom layer |
|
SS in mg L-1 (depth-averaged) at all monitoring stations and control stations |
95 percentile of baseline data or 120% of upstream control station's SS at the same tide of the same day |
99 percentile of baseline or 130% of upstream control station's SS at the same tide of the same day and 10mg/L for WSD Seawater intakes |
|
Turbidity in NTU (depth-averaged) |
95 percentile of baseline data or 120% of upstream control station's Turbidity at the same tide of the same day |
99 percentile of baseline or 130% of upstream control station's Turbidity at the same tide of the same day |
|
Nutrient in mg L-1 (depth-averaged) at all monitoring stations (except for locations for sensitive test result) Mf monitoring and control stations |
95 percentile of baseline data or 120% of upstream control station's nutrient level at the same tide of the same day |
99 percentile of baseline or 130% of upstream control station's nutrient level at the same tide of the same day and 10mg/L for WSD Seawater intakes |
|
Heavy metals in μg L-1 (depth averaged) (Cd, Cr, Cu, Hg, Ni , Pb, Ag, Zn, and As) at all monitoring stations(except for locations for sensitive result) Mf monitoring and control stations |
95 percentile of baseline data or 120% of upstream control station's nutrient level at the same tide of the same day |
(Note 6) Cd: 2.5μg/L; Cr: 15μg/L; Cu: 5μg/L; Hg: 0.3μg/L; Ni: 30μg/L; Pb: 25μg/L; Ag: 1.9μg/L; Zn: 40μg/L; and As: 25μg/L. |
Notes: 1. "depth-averaged" is calculated by taking the arithmetic means of reading of all three depths.
2. For DO, non-compliance of the water quality limits occurs when monitoring result is lower than the limits.
3. For turbidity, SS, non-compliance of the water quality limits occurs when monitoring result is higher than the limits.
4. For Mf locations, the action and limit levels will be determined separately and sought EPD agreement before the commencement of construction.
5. 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.
6. Limit values of most heavy metals (except Ag) are based on European Union Environmental Quality Standard (EQS) Values to Protect Marine Life. For Ag, the limit value is based on the Criteria Maximum Concentration (CMC) of the USEPA Water Quality Criteria (Saltwater)
5.12.1.2 The ET shall propose Action and Limit Levels for water quality for the relocation of Mf sediment for agreement with EPD.
Table 5.4 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 on next day of exceedance to confirm findings; Identify source(s) of impact; Inform IEC, contractor and ER; Check monitoring data, all plant, equipment and Contractor's working methods. |
Check monitoring data submitted by ET and Contractor’s working methods. |
Confirm receipt of notification of non-compliance in writing; Notify Contractor. |
Inform the ER and confirm notification of the non-compliance in writing; Rectify unacceptable practice; Amend working methods if appropriate. |
|
Action level being exceeded by two or more consecutive sampling days |
Repeat measurement on next day of exceedance to confirm findings; Identify source(s) of impact; Inform IEC, contractor, ER 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 Action level; |
Check monitoring data submitted by ET and Contractor’s working method; Discuss with ET and Contractor on possible remedial actions; Review the proposed mitigation measures submitted by Contractor and advise the ER accordingly; Supervise the implementation of mitigation measures. |
Discuss with IEC on the proposed mitigation measures; Ensure mitigation measures are properly implemented; Assess the effectiveness of the implemented mitigation measures. |
Inform the Engineer and confirm notification of the non-compliance in writing; Rectify unacceptable practice; Check all plant and equipment and consider changes of working methods; Submit proposal of additional mitigation measures to ER within 3 working days of notification and discuss with ET, IEC and ER; Implement the agreed mitigation measures. |
|
Limit level being exceeded by one sampling day |
Repeat measurement on next day of exceedance to confirm findings; Identify source(s) of impact; Inform IEC, contractor, ER and EPD; Check monitoring data, all plant, equipment and Contractor's working methods; Discuss mitigation measures with IEC, ER and Contractor;
|
Check monitoring data submitted by ET and Contractor’s working method; Discuss with ET and Contractor on possible remedial actions; Review the proposed mitigation measures submitted by Contractor and advise the ER accordingly. |
Confirm receipt of notification of failure in writing; Discuss with IEC, ET and Contractor on the proposed mitigation measures; Request Contractor to review the working methods. |
Inform the ER and confirm notification of the non-compliance in writing; Rectify unacceptable practice; Check all plant and equipment and consider changes of working methods; Submit proposal of mitigation measures to ER within 3 working days of notification and discuss with ET, IEC and ER. |
|
Limit level being exceeded by two or more consecutive sampling days |
Repeat measurement on next day of exceedance to confirm findings; Identify source(s) of impact; Inform IEC, contractor, ER 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; |
Check monitoring data submitted by ET and Contractor’s working method; Discuss with ET and Contractor on possible remedial actions; Review the Contractor’s mitigation measures whenever necessary to assure their effectiveness and advise the ER accordingly; Supervise the implementation of 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; Ensure mitigation measures are properly implemented; 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. |
Take immediate action to avoid further exceedance; Submit proposal of mitigation measures to ER within 3 working days of notification and discuss with ET, IEC and ER; Implement the agreed mitigation measures; Resubmit proposals of mitigation measures if problem still not under control; As directed by the Engineer, to slow down or to stop all or part of the construction activities until no exceedance of Limit level. |