A colony of 50 people is served by a septic tank. The rate of water supply is 90 lpcd in the colony and 40% of it is going to the septic tank. The retention period of the tank
Q. A colony of 50 people is served by a septic tank. The rate of water supply is 90 lpcd in the colony and 40% of it is going to the septic tank. The retention period of the tank is 24 hours. The length of the septic tank is___________________meter (rounded off to two decimal places).
Assume, storage capacity/person = 0.085m3 (3 years) Space for digestion = 0.0425 m3/person
Depth of tank = 1.4 m Length: Width = 2:1
A. 34.2
B. 3.42
C. 342
D. 0.342
Ans: 3.42
Water in septic tank = 50 × 90 × 1 × 0.4 = 1.8 cu. m (40% of total consumption)
Storage volume of septic tank = 0.085 × 50 = 4.25 cu. m
Digestion volume of septic tank = 0.0425 × 50 = 2.125 cu. m
Total volume = 1.8 + 4.25 + 2.125 = 8.175 cu. M
