Civil Engineering - Waste Water Engineering

21. 

To prevent settling down of sewage both at the bottom and on the sides of a large sewer, self-cleaning velocity recommended for Indian conditions, is

A. 0.50 m/sec
B. 0.60 m/sec
C. 0.70 m/sec
D. 0.75 m/sec
E. 1.0 m/sec.

Answer: Option D

Explanation:

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22. 

Pick up the correct statement from the following :

A. Turbidity is more in strong sewage
B. The black colour indicates septic sewage
C. The fresh sewage is practically odourless
D. The sewage omits offensive odours after four hours
E. All the above.

Answer: Option E

Explanation:

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23. 

In sewers the gas generally found, is

A. Hydrogen sulphide (H2S)
B. Carbon dioxide (CO2)
C. Methane (CH4)
D. Petrol vapours
E. All the above.

Answer: Option E

Explanation:

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24. 

A sewer running partially full and hurried with back filled, fails in compression due to

A. weight of the pipe
B. weight of the back fill
C. superimposed traffic loads
D. all the above.

Answer: Option D

Explanation:

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25. 

A manhole is classified as shallow if its depth is between

A. 0.4 to 0.5 m
B. 0.5 to 0.7 m
C. 0.7 to 0.9 m
D. 0.9 to 1.20 m
E. 1.2 to 1.50 m.

Answer: Option C

Explanation:

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