PORT WORKS DESIGN MANUAL PART 3 Guide To - The University ...

2,11 DrainageA reclamation project may cause adverse impacts on drainage and flooding by altering theexisting drainage paths and regime, or by increasing the burden on the existing drainagesystem. Existing drainage outfalls will need to be extended and temporarily diverted awayfrom the line of the extension while reclamation is carried out. A drainage impactassessment is also necessary at an early stage of the planning and design in order to assesspotential drainage and flooding problems. It must determine the necessary temporarydrainage diversion and permanent drainage measures to ensure acceptable drainageperformance in areas upstream, adjacent to and inside the reclamation during and after theconstruction of the reclamation. Close liaison with Drainage Services Department isnecessary for the drainage impact assessment. For details of drainage impact assessmentstudy, WBTC No. 18/95 (WB, 1995) should be referred to.During reclamation, care should be taken to check for existing outfalls, intakes and drainsalong the lines of the existing shoreline, particularly at low tide. Any outfalls, intakes ordrains which do not appear on the drawings should be recorded immediately and investigatedwith the appropriate authority. Temporary channels should be provided as necessary acrossthe reclamation as a short term measure to avoid any delay. This aspect should be indicatedin the contract.