• Collects sanitary sewage & storm water run off in a single pipe system.• Can cause serious water pollution problems due to combined seweroverflows• Caused by large variations in flow between dry and wet weather.• This type of sewer design is no longer used in building new communities.
• Used for transporting sewage from houses and commercial buildings• Sanitary sewers serving industrial areas also carry Industrial sewage.• Sanitary sewage is collected with the help of sanitary sewer line• The sanitary sewer is attached to a main sewer.• The main sewer runs directly to the sewage treatment plant.
• A storm sewer collects storm water with the help of gutter & catch basin• Gutter allow the storm water to drain from the street directly into the stormsewer.
ManholeDrop ManholeFlushing TankLamp holeVent shaftInverted SiphonStorm Water Inlets /Street InletsCover and FramesCatch Basin
Quantity of sewage to be handledLand use patternContour Layout
Design periodDischargeSelf cleansing velocity (Vmin)Scouring velocity (Vmax)Roughness of pipesDepth of sewerGradientPost monsoon ground water table
Design Period of Civil Work (Trunk,Main Branch Sewer & Appurtenances) - 30 YearsSewage Generated - 80% of Total Water supplyFlow Assumptions - Minimum Flow Variesfrom 1/3 to ½ of average flowGround Water Infiltration -500 to 5,000 litres/km/dayManning’s Roughness Coefficient - 0.013Velocity of Flow - 0.60 m/s to 3.0 m/sRate of Flow - 80% Running Full Minimum Size of Sewer - 150 mm
Minimum gradient for sewers shall be designed tofulfill the requirement of self cleansing velocityPresent Peak Flow(Cumec)Recommended slope1 in0.002 1650.003 2500.005 3200.010 5000.015 7700.020 8350.030 1000
ContributoryPopulation RangePeak FactorUp to 20,000 3.020,000 to 50,000 2.550,000 to 7,50,000 2.25Above 7,50,000 2.0
MANNINGS FORMULAandQ= A x VWhereQ = DischargeS = Slope of hydraulic gradientD = Internal dia of pipe lineR = Hydraulic radius in mV = Velocity in m/sn = Mannings roughness coefficient
The Problem has been taken from the Manual onSewerage and sewage Treatment-1993 of Central PublicHealth and Environmental Engineering Organization(CPHEEO). Layout Plan of Manual. Ground Levels of various nodes. Total Population of the Area is two Lacs. Total Area = 101.02 ha.
Average Length of sewer line between Manhole = 30 m Water supply = 150 L/C/day Total Population = 2 lacs Total Length of sewer line = 7275.12 m Population Equivalent = (200000/7275.12)= 27.49 Persons/m Rate of Infiltration = 5000 Lit/Km/Day Minimum cover to be provided overthe crown of the sewer = 1.0 m Minimum velocity in sewer at peak flow = 0.6 m/s Maximum Velocity in sewer = 2 m/s Minimum size of the sewer = 150 mm Peak factor = 3.0
Section From MH-69 to MH-70Diameter of Sewer Line = 150 mmMin. Velocity = 0.60 m/sSlope of the sewer Line = 1 in 160Detail Design
Layout Plan of the Area Sewer Network Hydraulic Design Sewer Lines Colour Coding Plan of the Network Typical L-section of Sewer Line Typical Details of Appurtenances Typical Details of Excavation Pipe Bedding
Sl.No.Descriptionof ItemMaximum Minimum1 Ground Level 39.00 Mtr. 32.00 Mtr.2 Discharge 0.625 Cumec 0.0027 Cumec(2.70 Lit.)3 Slope 1 in 1100 1 in 1004 Velocity 1.83 m/s 0.61 m/s5 Dia of Pipe 1000 mm 150 mm
Circular type manhole 0.91minternal diameter (atbottom) beyond 0.91m to1.67m129Circular type manhole 1.22minternal diameter (atbottom) beyond 1.68 m to2.29 m :67Circular type manhole 1.52 minternal diameter (atbottom) beyond 2.30 m :60
Total Cost of Excavation(Rs.) = 25.16 Lacs Total Cost Of Manholes (Rs.) = 33.83 Lacs Total Cost of Pipes (Rs.) = 33.08 Lacs Total Cost of Foot Rest (Rs.) = 3.69 Lacs Cost of P.C.C. (1.2.4) (Rs.) = 1.69 LacsTotal cost of the Project (Rs.) = 97.46 LacsAvg. cost / Km (Rs.) = 13.40 Lacs
Manual on sewerage and sewage treatment(Second edition-1993)Manual on sewerage and sewage treatment (FinalDraft-2012)Delhi Schedule of Rates – 2012,Delhi analysis of Rates Vol. I & II,Environmental Engineering Vol. II, by S.K.Garg(Twenty Second Edition)Basic Environmental Engineering by JeeryA.Nathson.www.google.co.in/Images for logo ofJamia, images and photos etc.