Code of practice on surface water drainage

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6.4
Earthworks

(a) The approval of the Board shall besought for all earthworks affecting the existing drainage system or the flow pattern of surface runoff. In the event that earthworks are to be carried out adjacent to major drains and canals, the developer/owner shall engage a Qualified Person to carryout soil investigation works and slope stability analysis to ensure that the earthworks will not cause any damage to the drainage structures. b) The developer owner shall take all necessary steps and measures, such as implementing suitable soil stabilisation methods and temporary protection works to ensure the stability and structural integrity of the existing drainage structures. c) Earth control measures shall be provided in accordance with the requirements as stipulated in Clause 6.3.
6.5
Road Works
A temporary drainage system shall be provided for all roadworks to prevent flooding or water ponding on the road. Where the road is being raised and the new road drainage outlets are at a higher level than the existing ones, the existing outlets shall not be blocked unless temporary alternative drainage system has been provided. The developer/owner and the Qualified Person shall be responsible for implementing all necessary measures to ensure that the site is kept flood free at all times. Where necessary, the Board may require the submission of hydraulic calculations, programme of works, temporary drainage arrangements at various stages of the roadworks, etc. by the Qualified Person.
6.6
Reclamation Works
6.6.1 All reclamation works shall be carried out in accordance with Clause 2.3 and 4.10.
6.6.2 During reclamation, a temporary drainage system including perimeter cutoff drains, silt- traps, silt fences and outlet connections shall be provided. The temporary drainage system shall include erosion protection linings, such as concrete, geotextile mattress and other suitable materials to be approved by the Board. The proposals of the temporary drainage system shall be submitted to the Board for approval.
6.6.3 The temporary drainage system shall be cleansed and maintained regularly by the reclamation agency to remove all obstructions, silt and rubbish during the reclamation period.

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