Cause of Impact
Potential water pollution sources have been identified as construction runoff, sewage from workforce, wastewater discharge from tunnelling and excavation, change of the groundwater table, and groundwater contamination.
During the operational phase, there would be no direct discharge of wastewater into Victoria Harbour anticipated. Potential water pollution sources during the operation would include the runoff from rail track and operational tunnel drainage.
In order to minimize water quality impacts during construction and operation, the following remedies will be applied:
- Applicable mitigation measures in accordance with ProPECC PN 1/94;
- Seepage of uncontaminated groundwater should be pumped out and discharged into storm system via silt removal facilities;
- Applying to EPD for a licence under Water Pollution Control Ordinance for the discharge of site effluent;
- The Contractor shall register as a chemical waste producer under the Waste Disposal (Chemical Waste) (General) Regulation;
- Any service shop and maintenance facilities should be located on hard standings within a bunded area, and sumps and oil interceptors should be provided;
- Disposal of chemical wastes should be carried out in compliance with the Waste Disposal Ordinance including the general requirements of using suitable containers, labelled containers and proper storage area; and
To mitigate any draw down effect to groundwater talk during the dewatering works:
- Toe grouting should be applied; and
- Recharge wells should be installed.
Measures for the tunnel run-off and drainage include:
- Track drainage channels discharge should pass through oil/grit interceptors/chambers;
- The silt traps and oil interceptors should be cleaned and maintained regularly; and
- Oily contents of the oil interceptors should be transferred to an appropriate disposal facility, or to be collected for reuse, if possible;
Measures for the control of sewage effluents include:
- Connection of domestic sewage generated from the KTE project should be diverted to the foul sewer wherever possible, or ensure all discharge comply with the requirements stipulated in the Technical Memorandum on Standards for Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal Waters; and
- Adopting the practices outlined in ProPECC PN 5/93 where applicable.
No adverse water quality impact is anticipated with the provision of good construction works practices. The sites should be regularly inspected and audited.
The track run-off and tunnel seepage during the operational phase would have no adverse water quality impact anticipated, provided that mitigation measures have been incorporated in the design.