0.3 0.6 0.5 Question 2 Figure below shows a catchment which is to be drained through an outfall sewer into a river. The catchment area covering a land of polygon ABCDEA consists of 3 zones, Zone 1, Zone 2 and Zone 3. The coordinates of A, B, C, D and E are given. The following data relate to the 3 zones: ZONE1 Zone 2 Zone Area 20% of total area 30% of total area 50% of total area Runoff Coefficient Inlet Time 10 min 15 min 17 min Sewer Info MH1 to MHZ; MH2 to MH3; Length = 120 m; Length = 160 m; velocity = 0.75 m/s Velocity = 0.75 m/s Outfall Sewer, MH3 to River: Length = 150 m; sewer invert elevation at MH3 = 75.5 m; Elevation of water level in river = 72.5 m The catchment is in the region where i= 3000/(t+20) Design the outfall sewer using Manning's formula (n=0.013) and assuming it to be circular and flowing full. (Hint: The sum of each y-coordinate multiplied by the difference between the two adjacent x-coordinates is twice the area of any closed traverse. The result will be the same as the sum of each x-coordinate multiplied by the difference between the two adjacent y-coordinates.) Marks: 20 D (250,550) Zone 1 C 1550,450) Zone 2 E (-150,320) Zone 3 B (500,100) A 10,00 0.3 0.6 0.5 Question 2 Figure below shows a catchment which is to be drained through an outfall sewer into a river. The catchment area covering a land of polygon ABCDEA consists of 3 zones, Zone 1, Zone 2 and Zone 3. The coordinates of A, B, C, D and E are given. The following data relate to the 3 zones: ZONE1 Zone 2 Zone Area 20% of total area 30% of total area 50% of total area Runoff Coefficient Inlet Time 10 min 15 min 17 min Sewer Info MH1 to MHZ; MH2 to MH3; Length = 120 m; Length = 160 m; velocity = 0.75 m/s Velocity = 0.75 m/s Outfall Sewer, MH3 to River: Length = 150 m; sewer invert elevation at MH3 = 75.5 m; Elevation of water level in river = 72.5 m The catchment is in the region where i= 3000/(t+20) Design the outfall sewer using Manning's formula (n=0.013) and assuming it to be circular and flowing full. (Hint: The sum of each y-coordinate multiplied by the difference between the two adjacent x-coordinates is twice the area of any closed traverse. The result will be the same as the sum of each x-coordinate multiplied by the difference between the two adjacent y-coordinates.) Marks: 20 D (250,550) Zone 1 C 1550,450) Zone 2 E (-150,320) Zone 3 B (500,100) A 10,00