4. WATER QUALITY MONITORING
4.1 Monitoring Locations
4.1.1 The water monitoring works for the Contract are covered by Contract No. HY/2013/01 “Hong Kong-Zhuhai-Macao-Bridge HKBCF – Passenger Clearance Building”. The ET of the Contract or another ET of the HZMB project is required to conduct impact water quality monitoring at the stations shown in Table 4.1 and Figure 3.
Table 4.1 Water Quality Monitoring Stations
Station |
Description |
Easting |
Northing |
IS5 |
Impact Station (Close to HKBCF construction site) |
811579 |
817106 |
IS(Mf)6 |
Impact Station (Close to HKBCF construction site) |
812101 |
817873 |
IS7 |
Impact Station (Close to HKBCF construction site) |
812244 |
818777 |
IS8 |
Impact Station (Close to HKBCF construction site) |
814251 |
818412 |
IS(Mf)9 |
Impact Station (Close to HKBCF construction site) |
813273 |
818850 |
IS10(N) |
Impact Station (Close to HKBCF construction site) |
812942 |
820881 |
IS(Mf)11 |
Impact Station (Close to HKBCF construction site) |
813562 |
820716 |
IS(Mf)16 |
Impact Station (Close to HKBCF construction site) |
814328 |
819497 |
IS17 |
Impact Station (Close to HKBCF construction site) |
814539 |
820391 |
SR3 |
Sensitive receivers (San Tau SSSI) |
810525 |
816456 |
SR4(N) |
Sensitive receivers (Tai Ho) |
814705 |
817859 |
SR5(N) |
Control Station |
812569 |
821475 |
SR6 |
Sensitive receivers (Sha Chau and Lung Kwu Chau Marine Park) |
805837 |
821818 |
SR7 |
Sensitive receivers (Tai Mo Do) |
814293 |
821431 |
SR10A(1) |
Sensitive receivers(Ma Wan FCZ) 1 |
823741 |
823495 |
SR10B(N)(1) |
Sensitive receivers(Ma Wan FCZ) 2 |
823683 |
823187 |
CS(Mf)3(N) |
Control Station |
808814 |
822355 |
CS(Mf)5 |
Control Station |
817990 |
821129 |
CS4 |
Control Station |
810025 |
824004 |
CS6 |
Control Station |
817028 |
823992 |
CSA(2] |
Control Station |
818103 |
823064 |
Note:
(1) Additional monitoring station for ma Wan FCZ
(2) Additional control monitoring station for Ma Wan FCZ
Remarks:
The ET of the Contract should conduct impact water quality monitoring at the WQMs listed in the table as part of EM&A programme according to latest notification from ENPO if water quality monitoring is no longer covered by another ET of the HZMB project. The ET of the Contract shall communicate and share the monitoring data to the ET(s) of the other contracts if the water quality monitoring station(s) is/are as part of EM&A programme.
4.2 Monitoring Requirements
4.2.1 The monitoring requirements, monitoring equipment, monitoring parameters, frequency and duration, monitoring methodology, monitoring schedule, meteorological information are detailed in the monthly EM&A Reports prepared by Contract No. HY/2013/01.
4.2.2 The event and action plan is provided in Appendix D.
4.2.3 The Action and Limit Levels for Water Quality are provided in Table 4.2.
Table 4.2 Action and Limit Levels for Water Quality
Parameters |
Action |
Limit |
DO in mg/L (Surface, Middle & Bottom) |
Surface and Middle 5.0 Bottom 4.7 |
Surface and Middle = 4.2 (except 5 mg/L for FCZ) Bottom = 3.6 |
SS in mg/L (depth-averaged) at all monitoring stations and control stations |
23.5 and 120% of upstream control station's SS at the same tide of the same day* |
34.4 and 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) |
27.5 and 120% of upstream control station's turbidity at the same tide of the same day* |
47.0 and 130% of upstream control station's turbidity at the same tide of the same day* |
* Remarks: Reference is made to EPD approval of adjustment of water quality assessment criteria issued and became effective on 18 February 2013.
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. 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.
5. The 1%-ile of baseline data for dissolved oxygen (surface and middle) and dissolved oxygen (bottom) are 4.2mg/L and 3.6mg/L respectively.
4.2.4 If exceedance(s) at these stations is/are recorded by the ET of the Contract or referred by the other ET under the HZMB project to the Contract, the ET of the Contract will carry out an investigation and findings will be reported in the monthly EM&A Report.
4.3 Monitoring Results
4.3.1 The monitoring results for the monitoring stations showed in Table 4.1 are reported in the monthly EM&A Report prepared for Contract No. HY/2013/01. There was Action and Limit Level exceedance recorded at different WQM stations during mid-ebb and mid-flood tide on twelve days. The summary of water quality exceedances are shown in Table 4.3.
Table 4.3 Action and Limit Levels for Water Quality
Station |
Exceedance Level |
DO (S&M) |
DO (Bottom) |
Turbidity |
SS |
||||
Ebb |
Flood |
Ebb |
Flood |
Ebb |
Flood |
Ebb |
Flood |
||
IS5 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS(Mf6) |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS7 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS8 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS(Mf)9 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS10(N) |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS(Mf)11 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 (20 Oct) |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS(Mf)16 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
IS17 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR3 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR4(N) |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR5(N) |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
3 (18 Oct, 20 Oct, 23 Oct) |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR6 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR7 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 (20 Oct) |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR10A |
Action |
0 |
0 |
2 (2 Oct, 4 Oct) |
2 (2 Oct, 4 Oct) |
0 |
0 |
0 |
0 |
Limit |
1 (4 Oct) |
1 (4 Oct) |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR10B(N) |
Action |
0 |
0 |
0 |
3 (2 Oct, 4 Oct, 6 Oct) |
0 |
0 |
0 |
0 |
Limit |
2 (4 Oct, 6 Oct) |
4 (2 Oct, 4 Oct, 6 Oct, 9 Oct) |
0 |
0 |
0 |
0 |
0 |
0 |
Note: S&M: Surface & Middle
4.3.1
4.3.2 Regarding the exceedance on 2 October 2017, there was marine
transportation on the date of exceedance. Regarding marine transportation, the
vessels was sized to make sure adequate clearance is maintained between vessels
and the sea bed at all states of the tide to ensure that undue turbidity is not
generated by turbulence from vessel movement or propeller wash. Regarding
marine-based works in Box Culvert B, the work undertaken at the date of
exceedance was preparation work of precast installation which had a cofferdam
to separate seawater and works area. Silt curtain was also maintained to
enclose the work area of the outlet of the box culvert fully. All sea water
flows into the work area of box culvert B will be treated by desilting
facilities before discharge in accordance with the discharge license approved
by EPD for Contract No. HY/2013/03. In addition, the concerned WQM stations
where the exceedances were recorded were far away from the marine works area of
Contract No. HY/2013/03, while there was no notification of exceedance received
at the WQM stations closer to the works areas, such as IS(Mf)11.
It was unlikely to consume any dissolved oxygen to cause the DO exceedances
recorded at the concerned WQM stations during mid-flood and mid-ebb tide on 2
October 2017.
4.3.2
Regarding the exceedance on 4 October 2017, there was marine
transportation on the date of exceedance. Regarding marine transportation, the
vessels was sized to make sure adequate clearance is maintained between vessels
and the sea bed at all states of the tide to ensure that undue turbidity is not
generated by turbulence from vessel movement or propeller wash. Regarding marine-based works
in Box Culvert B, the work undertaken at the date of exceedance was preparation
work of precast installation which had a cofferdam to separate seawater and
works area. Silt curtain was also maintained to enclose the work area of the
outlet of the box culvert fully. All sea water flows into the work area of box
culvert B will be treated by desilting facilities before discharge in
accordance with the discharge license approved by EPD for Contract No.
HY/2013/03. In addition, the concerned WQM stations where the exceedances were
recorded were far away from the marine works area of Contract No. HY/2013/03,
while there was no notification of exceedance received at the WQM stations
closer to the works areas, such as IS(Mf)11. It was
unlikely to consume any dissolved oxygen to cause the DO exceedances recorded
at the concerned WQM stations during mid-flood and mid-ebb tide on 4 October
2017.
4.3.3
Regarding the exceedance on 6 October 2017, there was marine
transportation on the date of exceedance. Regarding marine transportation, the
vessels was sized to make sure adequate clearance is maintained between vessels
and the sea bed at all states of the tide to ensure that undue turbidity is not
generated by turbulence from vessel movement or propeller wash. Regarding
marine-based works in Box Culvert B, the work undertaken at the date of
exceedance was preparation work of precast installation which had a cofferdam
to separate seawater and works area. Silt curtain was also maintained to
enclose the work area of the outlet of the box culvert fully. All sea water
flows into the work area of box culvert B will be treated by desilting
facilities before discharge in accordance with the discharge license approved
by EPD for Contract No. HY/2013/03. In addition, the concerned WQM stations
where the exceedances were recorded were far away from the marine works area of
Contract No. HY/2013/03, while there was no notification of exceedance received
at the WQM stations closer to the works areas, such as IS(Mf)11.
It was unlikely to consume any dissolved oxygen to cause the DO exceedances
recorded at the concerned WQM stations during mid-flood and mid-ebb tide on 6
October 2017.
4.3.4
Regarding the exceedance on 9 October 2017, there was marine
transportation on the date of exceedance. Regarding marine transportation, the
vessels was sized to make sure adequate clearance is maintained between vessels
and the sea bed at all states of the tide to ensure that undue turbidity is not
generated by turbulence from vessel movement or propeller wash. Regarding
marine-based works in Box Culvert B, the work undertaken at the date of
exceedance was preparation work of precast installation which had a cofferdam
to separate seawater and works area. Silt curtain was also maintained to
enclose the work area of the outlet of the box culvert fully. All sea water
flows into the work area of box culvert B will be treated by desilting
facilities before discharge in accordance with the discharge license approved
by EPD for Contract No. HY/2013/03. In addition, the concerned WQM stations
where the exceedances were recorded were far away from the marine works area of
Contract No. HY/2013/03, while there was no notification of exceedance received
at the WQM stations closer to the works areas, such as IS(Mf)11.
It was unlikely to consume any dissolved oxygen to cause the DO exceedances
recorded at the concerned WQM stations during mid-flood on 9 October 2017.
4.3.5
Regarding the exceedance on 18 October 2017, there was marine
transportation on the date of exceedance. Regarding marine transportation, the
vessels was sized to make sure adequate clearance is maintained between vessels
and the sea bed at all states of the tide to ensure that undue turbidity is not
generated by turbulence from vessel movement or propeller wash. For SS
exceedance recorded at the WQM station SR5(N), the
concerned WQM stations where the exceedances were recorded were not close to
the marine delivery route of Contract No. HY/2013/03, while there was no
notification of exceedance received at the WQM stations closer to the marine
delivery route, such as IS(Mf)11. Regarding
marine-based works in Box Culvert B, the work undertaken at the date of
exceedance was preparation work of precast installation which had a cofferdam
to separate seawater and works area. Silt curtain was also maintained to
enclose the work area of the outlet of the box culvert fully. All sea water
flows into the work area of box culvert B will be treated by desilting
facilities before discharge in accordance with the discharge license approved
by EPD for Contract No. HY/2013/03. In addition, the concerned WQM stations
where the exceedances were recorded were far away from the marine works area of
Contract No. HY/2013/03, while there was no notification of exceedance received
at the WQM stations closer to the works areas, such as IS(Mf)11.
It was unlikely that the works undertaken by Contract No. HY/2013/03 caused SS
exceedance recorded at the concerned WQM station during mid-flood tide on 18
October 2017.
4.3.6
Regarding the exceedance on 20 October 2017, there no marine
transportation on the date of exceedance. Regarding marine transportation, the
vessels was sized to make sure adequate clearance is maintained between vessels
and the sea bed at all states of the tide to ensure that undue turbidity is not
generated by turbulence from vessel movement or propeller wash. For SS
exceedance recorded at the WQM station IS(Mf11),
SR5(N) and SR 7, the concerned WQM stations where the exceedances were recorded
were not close to the marine delivery route of Contract No. HY/2013/03, while
there was no notification of exceedance received at the WQM stations closer to
the marine delivery route, such as IS10(N). Regarding
marine-based works in Box Culvert B, the work undertaken at the date of
exceedance was preparation work of precast installation which had a cofferdam
to separate seawater and works area. Silt curtain was also maintained to
enclose the work area of the outlet of the box culvert fully. All sea water
flows into the work area of box culvert B will be treated by desilting
facilities before discharge in accordance with the discharge license approved
by EPD for Contract No. HY/2013/03. For SS exceedance recorded at the WQM
station SR7, there was no SS exceedance recorded at the same WQM station under
similar work environment on 18 October 2017 and 23 October 2017. For SS
exceedance recorded at the WQM station SR5(N), the
concerned WQM stations where the exceedances were recorded were not close to
the marine works area of Contract No. HY/2013/03, while there was no
notification of exceedance received at the WQM stations closer to the works
areas, such as IS10(N). For SS exceedance recorded at
the WQM station IS(Mf)11 closer to the works area Box
Culvert B, there was no SS exceedance recorded at the same WQM station under
similar work environment on 18 October 2017 and 23 October 2017. There was a
complaint received by EPD with discharge concern around the date of exceedance.
As confirmed with Mr. Marko Chan, Environmental Officer, and operation team of
Contract No. HY/2013/03, there was no discharge activities during the
complained period. It was unlikely that the works undertaken by Contract No.
HY/2013/03 caused SS exceedance recorded at the concerned WQM station during
mid-flood tide on 20 October 2017.
4.3.7
Regarding the exceedance on 23 October 2017, there was marine
transportation on the date of exceedance. Regarding marine transportation, the
vessels was sized to make sure adequate clearance is maintained between vessels
and the sea bed at all states of the tide to ensure that undue turbidity is not
generated by turbulence from vessel movement or propeller wash. For SS
exceedance recorded at the WQM station SR5(N), the
concerned WQM stations where the exceedances were recorded were not close to
the marine delivery route of Contract No. HY/2013/03, while there was no
notification of exceedance received at the WQM stations closer to the marine
delivery route, such as IS(Mf)11. Regarding
marine-based works in Box Culvert B, the work undertaken at the date of
exceedance was preparation work of precast installation which had a cofferdam
to separate seawater and works area. Silt curtain was also maintained to
enclose the work area of the outlet of the box culvert fully. All sea water
flows into the work area of box culvert B will be treated by desilting
facilities before discharge in accordance with the discharge license approved
by EPD for Contract No. HY/2013/03. In addition, the concerned WQM stations
where the exceedances were recorded were far away from the marine works area of
Contract No. HY/2013/03, while there was no notification of exceedance received
at the WQM stations closer to the works areas, such as IS(Mf)11.
It was unlikely that the works undertaken by Contract No. HY/2013/03 caused SS
exceedance recorded at the concerned WQM station during mid-flood tide on 23
October 2017.