determine the pipe size for each of the sewer section by rat

determine the pipe size for each of the sewer section by rational method. The rainfall intensity (in/hr) is given by the IDF curve in second figure. The design frequency storm is 10-year storm. Flow from each area is shown by an arrow. 2. For the drainage system as shown in figure below, determine the design flow and The flow velocity in each pipe can be calculated by Manning\'s equation or con on for peak flows. Assume m equation by assuming a Hazen-Willia that the pipe material is concrete. Verify all the pipe flow velocities and time of concentration at the end of calculation. Unit Area(ac) Runoff Coeficient C Overland flow time (min) 0.60+0.0X 0.65+0.0X 0.75+0.0X 0.70+0.0X 0.80+0.0X 0.70+0.0X 0.65+0.0X 0.75+0.0X 0.5 X-last-digit of your Student ID 30.9 8 C 0.9 10 12 14 G 0.7 H 0.4 Pipe Lengths Feet Slope 1-2 2-3 3-5 4-5 500 0.004 480 0.0075 600 0.0075 1100 0.0065 6-7 600 0.0055 7-8 400 0.0036 600 0.0075 700 0.008 6-7 5-9

Solution

My student ID is 4 so i assume x as 4 and I am proceding

Runoff is given from the graph which is given above and from that particular graph the values of runoff are plotted in inches per hour based on approximate plotting of graph i have taken the values

The discharge here is calculated in m³/sec

so 1 acre=0.40 ha

1 inches=25.4mm

Q=A*I*R/360

As the pipe is circular, hydraulic radius=D/4 for each and every pipe and assume C=100 for concrete pipe

calculate Diameter in m

slope=H/L, here H=D( because diameter is the height in a pipe)

V=KCR^0.63S^0.54 ( assume K as 0.849)

0.0075

the time of concentration is given by

Tc=0.0025x(L/S)^0.5

consdier the length in m

UNIT	AREA	COEFF. OF RUNOFF	OVERFLOW TIME
A	0.5	0.64	5
B	0.9	0.69	11
C	0.9	0.79	10
D	1.4	0.74	12
E	1.4	0.84	14
F	1	0.74	11
G	0.7	0.69	8
H	0.4	0.79	6