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 ¡V
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(N) |
Sensitive
receivers (San Tau SSSI) |
810689 |
816591 |
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(N)(1) |
Sensitive
receivers (Ma Wan FCZ) 1 |
823644 |
823484 |
SR10B(N2)(1) |
Sensitive
receivers (Ma Wan FCZ) 2 |
823689 |
823159 |
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
one WQM station during mid-ebb on one day. The summary of water quality
exceedances is 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 |
0 |
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 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR6 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
1 (31
Jan) |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR7 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR10A |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
SR10B(N) |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Note:
S&M: Surface & Middle
4.3.2
Regarding the exceedance on 31 January 2018, there was no marine
transportation on the date of exceedance. 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 SR6, 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 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-ebb tide on 31
January 2018.