BANGLADESH POWER DEVELOPMENT BOARD TENDER ... - BPDB

17.7.2 Gravel SurfacingThe Contractor shall supply and place a layer of gravel not less than 10cm inareas other than the paved and lawned areas in the power station as shown onthe Drawing or as directed by the Board. Materials for graveling shall be 3 to 7cmin size conforming to the grading requirement of the Specification.17.7.3 Landscaping And TurfingAreas around the power house building, administration building shall he turfed asshown on the Drawings or as directed by the Board.Turf shall be freshly cut approved carpet grass free from thorns and weeds. Thearea to be turfed shall be provided with a layer of 20cm top soil suitable for thegrowth of the lawn. The Contractor shall maintain and replace all dead turf at hisown expense until the end of maintenance period.The Contractor shall submit a detailed proposal on landscaping for the Site. Trees,flowers and other plants adaptable to the climate and soil conditions of the Siteshall be planted in the open spaces provided adjacent to the control andadministration building area and along the perimeter of the boundaries to form agreen belt around the power station. A proposal which shall include a landscapedrawing with a schedule showing types of trees, planting positions and otherdetails shall be submitted to the Board for approval.17.8 Drainage System17.8.1 Design ConditionsThe design of the storm water drainage system comprising the interceptor,roadside and perimeter drains for buildings, powerhouse, and switchyard shall besubmitted to the Board for approval.The Contractor shall carry out detailed designs of the storm water drains usingthe rational method or other approved procedures. The work shall be carried outin accordance with the rules and regulations of the local and other authorities.Design conditions for drainage system shall be as follows :Rainfall intensity100 mm/hrRun-off coefficient 0.6Manning's roughness coefficient 0.013for concrete lined channelAll drains or channels shall be concrete lined. Concrete sumps, silt traps, screensand drain covers shall be incorporated in the design where it is appropriate.17.8.2 Drain LayingAll trenches and drains are to be set out accurately to line and fall as specified.Ghorasal 200 MW to 300 MW Gas Turbine Peaking Power Plant Project (Vol-2 of 3)180