Question: 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_________________?

• 1. 0.50 m/sec
• 2. 0.60 m/sec
• 3. 0.70 m/sec
• 4. 0.75 m/sec

Question: Pick up the incorrect statement from the following for allowing workers to enter sewers_______________?

• 1. The particular manhole and one manhole on upstream and one manhole on downstream should remain open for 30 minutes
• 2. Proper tests for the presence of poisonous gases must be carried out
• 3. The men entering the manhole should be advised to smoke in the sewer
• 4. Warning signals should be erected

Question: The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is____________________?

• 1. 30 minutes
• 2. 1 hour
• 3. 1 hour and 30 minutes
• 4. 2 hours

Question: The discharge per unit plan area of a sedimentation tank, is generally called________________?

• 1. Over flow rate
• 2. Surface loading
• 3. Over flow velocity
• 4. All the above

Question: The gas which may cause explosion in sewers, is_________________?

• 1. Carbondioxide
• 2. Methane
• 3. Ammonia
• 4. Carbon monoxide

Question: The layers of vegetable wastes and night soil alternatively piled above the ground to form a mound, is called_______________?

• 1. A heap
• 2. Plateau
• 3. Windrow
• 4. None of these

Question: Pick up the correct statement from the following ?

• 1. Turbidity is more in strong sewage
• 2. The black colour indicates septic sewage
• 3. The sewage omits offensive odours after four hours
• 4. All the above

Question: Pick up the correct statement from the following?

• 1. The boning rod is used for checking the levels of the sewer inverts
• 2. Manhole covers are made circular for the convenience of the cleaning staff
• 3. A manhole is classified as shallow manhole if its depth is less than 0.9 m
• 4. All the above

Question: Pick up the correct statement from the following?

• 1. pH value indicates acidity and alkalinity of sewage
• 2. In acidic sewage, the pH value is less than 7
• 3. In alkaline sewage, the pH value is more than 7
• 4. All the above

Question: Pick up the correct statement from the following?

• 1. Indore method of composting involves decomposition under aerobic conditions
• 2. Bangalore method of composting involves decomposing under anaerobic conditions
• 3. Fully stabilised refuse by the Bangalore method of compositing is a powdery mass called humus
• 4. all of these