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A colony of 50 people is served by a septic tank. The rate of water supply is 90lped 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 = 0.085 m3 (year)
Space for digestion = 0.0425 m3 /person
Depth of tank = 1.4 m ; Length : Width = 2 : 1
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- 34.2
- 3.42
- 342
- 0.342
Correct Option: B
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
| Area of plane = | = | = 5.84 Sq m | ||
| Height | 1.4 |
If width is ‘a’, length will be ‘2a’
2a2 = 5.84
a = √(2.92) = 1.7
Length of septic tank = 2a = 2 × 1.7 = 3.4 m
