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 water quality monitoring station (SR3, SR10A and SR10B(N)) had been slightly re-located since 22 December 2017. 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 |
|
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 |
Sensitive receivers (Ma Wan FCZ) 1 |
823741 |
823495 |
|
SR10A(N)(1) |
Sensitive receivers (Ma Wan FCZ) 1 |
823644 |
823484 |
|
SR10B(N) |
Sensitive receivers (Ma Wan FCZ) 2 |
823683 |
823187 |
|
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. SR3(N), SR10A(N) and SR10B(N2) are alternative WQM Stations.
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 eight days. 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 |
1 (13 Dec) |
2 (6 Dec, 8 Dec) |
|
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
IS(Mf)9 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
1 (11 Dec) |
1 (6 Dec) |
|
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 |
1 (8 Dec) |
|
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
SR5(N) |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 (6 Dec) |
|
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
SR6 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
3 (4 Dec, 8 Dec, 22 Dec) |
3 (6 Dec, 20 Dec, 22 Dec) |
|
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
|
SR7 |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 (4 Dec) |
|
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
|
SR10A |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 (8 Dec) |
|
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
|
|
SR10B(N) |
Action |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 (4 Dec) |
|
Limit |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
Note: S&M: Surface & Middle
4.3.2 Regarding the exceedance on 4 December 2017, 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, SR7 and SR10B(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 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 and mid-flood tide on 4 December 2017.
4.3.3 Regarding the exceedance on 6 December 2017, 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 IS8, IS(Mf)9, SR5(N) and 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-flood tide on 6 December 2017.
4.3.4 Regarding the exceedance on 8 December 2017, 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 IS8, SR4(N), SR6 and SR10A, 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 and mid-flood tide on 8 December 2017.
4.3.5 Regarding the exceedance on 11 December 2017, 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 IS(Mf)9, 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 11 December 2017.
4.3.6 Regarding the exceedance on 13 December 2017, 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 IS8, 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 13 December 2017.
4.3.7 Regarding the exceedance on 20 December 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 SR6, 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. 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-flood tide on 20 December 2017.
4.3.8 Regarding the exceedance on 22 December 2017, 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 and mid-flood tide on 22 December 2017.