annexures - Indian Institute of Technology Roorkee

Chapter - 4 Preparation of Feasibility Report of Sewerage SchemesFuture population, which appears to be more realistic and acceptable, shall be adopted givingproper justification for the same.4.6 SEWERAGE MASTER PLANNING / SEWERAGE DISTRICTSMaster plan of the city shall be prepared for sewerage, if not prepared earlier. Considering thetopography and geographical features, ridge lines, alignment of drains, railway tracks, majorroads, national highways, encroachments, quicker construction and commissioning of worksand availability of land for SPS and STP etc., the whole city shall be divided into a number ofsewerage districts. Attempt should be made to avoid long sewers, as sewers will not berequired to be laid at large depths and also intermediate pumping stations would be avoided orreduced. To the extent possible, pumping should be avoided. This may entail a larger number ofsmall STPs as against large STPs but fewer in number.The design of works in these districts shall be carried out in an integrated manner taking intoconsideration the most optimum options from techno-economic perspective with respect tointerception of waste water, alignment of sewers, sewage pumping stations and sewagetreatment plants etc. Topography of the area, gradient, obstructions, etc. shall be taken intoaccount while planning the interception and diversion of waste water of the contributoryareas.4.7 RATE OF WATER SUPPLYAccording to the guidelines of Government of India, which are applicable all over the country,following water supply rates are to be adopted.Table 4.3: Recommended Per Capita Water Supply Levels for Designing SchemesS.No.Classification of citiesRecommended MaximumWater Supply Levels (lpcd)1 Cities provided with piped water supply but without70sewerage system2 Cities provided with piped water supply where sewerage135system is existing/ contemplated3 Metropolitan and Mega cities provided with piped watersupply where sewerage system is existing/ contemplated 150NOTE:1. In urban areas, where water is provided through public stand posts, 40 lpcd should beconsidered.2. Figures exclude “unaccounted for water (UFW), which should be limited to 15%.3. Figures include requirements of water for commercial, institutional and minor industries.However, bulk supply to such establishments should be assessed separately with properjustification.4. However, the actual rate of supply of water should be supported with availability of water inthe town.36