Secondary drainage channel KT13 has been proposed in the Yuen Long, Kam Tin, Ngau Tam Mei and Tin Shui Wai Drainage Master Plan (YLDMP) to drain the areas in Ma On Kong where the existing streamcourse is insufficient, to deal with catchwater overflows for Ho Pui Reservoir to the south and to provide infrastructure for future development.
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In order to improve the hydraulic performance of the streamcourse, the downstream section (Section A) of the streamcourse is widened and deepened to a trapezoidal channel with 5m wide gabion base and banks, and depth 3m. The upstream section (Section B) is also trained to a trapezoidal channel with 5m wide gabion base and banks with a constant depth of 2m. |
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A concrete bypass culvert will be built for the middle section of Ma On Kong streamcourse with the maintenance access to be formed above the bypass culvert. The bypass culvert is a twin cell box culvert. With the bypass culvert, the flow in the middle section of Ma On Kong streamcourse can be controlled so that there will be no overbank flow during a 1 in 50 years storm, while maintaining dry weather flow similar to existing condition in the unmodified existing middle section of the KT13 stream to ensure protection of Ho Pui Egretry and associated habitat. |
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The main ecological impacts identified include the loss of habitats and potential disturbance to the Ho Pui egretry. Practical mitigation measures have been formulated following the general policy for mitigating impacts under the Technical Memorandum on EIA Process which are Avoidance, Minimizing and Compensation. Avoidance is adopted in the channel design through careful alignment selection and the use of bypass channel to avoid the Ho Pui egretry and channelisation of the stream near the egretry, loss of CA zone and the nearby woodland. Minimization is achieved by reducing the duration & length of the construction works and restricting access to sensitive areas during construction. Screen planting and the use of gabion channel design will minimized the associated impacts during operation. Compensation planting will be provided for the habitat loss and to enhance a stream side area to become suitable habitat for egrets. |
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Title of Designated Project
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Yuen Long, Kam Tin, Ngau Tam Mei and Tin Shui Wai Drainage Improvement Stage 1, Phase 2B - Kam Tin Secondary Drainage Channel KT13
[This designated project is hereinafter referred to as “the Project”]
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Nature of Designated Project
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Drainage works
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Location of Designated Project
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Ma On Kong, Kam Tin
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Scale and Scope of Designated Project(s)
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To construct and operate a drainage channel which discharges into an area which is less than 300m from the nearest boundary of an existing conservation area and a bypass culvert which is partly in an existing conservation area
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Location(s) / Alignment(s) of this Project: |
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