MCQ 16 For a continuous flow type of sedimentation tanks

(A) Width of the tank is normally kept about 6 m (B) Length of the tank is normally kept 4 to 5 times the width (C) Maximum horizontal flow velocity is limited to 0.3 m/minute (D) All of the above

MCQ 12 The asbestos cement sewers are

(A) Light in weight (B) Not structurally strong to bear large compressive stress (C) Susceptible to corrosion by sulphuric acid (D) All of the above

MCQ 6 For efficient working of a sewer, it must be ensured that

(A) Minimum velocity of 0.45 m/sec, is maintained at its minimum flow (B) A maximum velocity of 0.90 m/sec, is maintained at its maximum flow (C) Both (A) and (B) (D) Neither (A) nor (B)

MCQ 13 Pick up the correct statement from the following:

(A) The sewer pipes of sizes less than 0.4 m diameter are designed as running full at maximum discharge (B) The sewer pipes of sizes greater than 0.4 m diameter are designed as running 2/3rd or 3/4th full at maximum discharge (C) The minimum design velocity of sewer pipes is taken as 0.8 m/sec (D) All of the above

MCQ 5 Bottom openings 15 cm × 15 cm in the standing baffle wall are provided

(A) 15 cm c/c (B) 22.5 cm c/c (C) 30 cm c/c (D) 50 cm c/c

MCQ 14 No treatment of the sewage is given if dilution factor is

(A) Less than 150 (B) Between 150 to 200 (C) Between 200 to 300 (D) More than 500

MCQ 7 Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is?

(A) Centrifugal pump (B) Pneumatic ejector (C) Reciprocating pump (D) None of these

MCQ 4 Pick up the correct statement from the following:

(A) Small sewers are cleaned by flushing (B) Medium sewers are cleaned by cane rodding (C) Medium sewers may be cleaned by pills (D) All of the above

MCQ 8 Pick up the correct statement from the following:

(A) The water supply pipes carry pure water free from solid particles (B) The water supply pipes get clogged if flow velocity is less than self cleansing velocity (C) The sewers may be carried up and down the hills and valleys (D) The sewer pipes are generally laid along level hills

MCQ 3 Pick up the incorrect statement from the following:

(A) The process of decomposing the organic matter under controlled anaerobic conditions, is called sludge digestion (B) Sludge digestion is carried out in sludge tank (C) The gases produced in sludge digestion process, contain 75% carbon dioxide (D) The gases produced in sludge digestion process, contain 75% methane

MCQ 11 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

(A) 30 minutes (B) 1 hour (C) 1 hour and 30 minutes (D) 2 hours

MCQ 9 Pick up the incorrect statement from the following for allowing workers to enter sewers

(A) The particular manhole and one manhole on upstream and one manhole on downstream should remain open for 30 minutes (B) Proper tests for the presence of poisonous gases must be carried out (C) The men entering the manhole should be advised to smoke in the sewer (D) Warning signals should be erected

MCQ 2 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

MCQ 10 The drainage area of a town is 12 hectares. Its 40% area is hard pavement ( K = 0.85), the 40% area is unpaved streets (K = 0.20) and the remaining is wooded areas (K = 0.15). Assuming the time of concentration for the areas as 30 minutes and using the formula Ps = 900/(t + 60) the maximum run off is

(A) 0.10 cumec (B) 0.12 cumec (C) 0.15 cumec (D) 0.20 cumec

MCQ 15 Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for

(A) Unexpected large scale infiltration of stream water (B) Unexpected increase in the population (C) Under estimates of maximum and average flows (D) All of the above

MCQ 1 The rational formula for peak drainage discharge, was evolved by

(A) Fruhling (B) Lloyd David (C) Kuichling (D) All of these