Question

Flow in Sewers

What are the minimum and maximum flowrates for sanitary and storm sewer? What is the reason (rationale) for applying such minimum and maximum for each sewer type? Present answer in Tabulation

Answer 1

Flow in lewers O designed Sanitary Sewres - designed to carry Peak dechange ie Max Hously discharge & checked to ensure that at Mirm Discharge (minn Hourly full velocity generated should be greater than self-cleansing to Run Pastially discharge Velocity * Reason Max flow = (Peaking factor) & Aug. flow Values of Peaking factor | Peaking factor to decade diameter & pipe Population Opto 20000 20000 - 50000 2.5 2.25 S0000 - 750000 > 50000 2.0 * 2) Minm flow = 1 to I of avg. flow. Reason: - To ensure self cleansing Velocity Stoom sewer → its design requires u 0 estimation of peak sunoff date for design. Peak sunoff de bends on 'Intensity of sainfall ' it depends on Reocersonce interval & duration of rainfall Peak Runoff (marm flow) calculated using Rational Formula [RECIA B = CiA - Runoff coeff. = runoff sain flow - intensity of sanfall. A- catchment area. Rainfall intensity (8) = Point Rainfall internity & Arcal dispersion factor. e, so a causar To – hr (Time of concentration) Design (i= tot 14 also i = 75 Tc + 10 (5 s TC 320) Tc- in minutes) foo (20 < To <100) Tc + 20