A sewer pipe contains 1 mm sand particles of specific gravity 2.65 and 5 mm organic particles of specific gravity 1.2, the minimum velocity required for removing the sewerage, is_____________________?
(A) 0.30 m/sec
(B) 0.35 m/sec
(C) 0.40 m/sec
(D) 0.45 m/sec
The sewer which collects the discharge from a collecting system and delivers it to a treatment plant, is known_____________________?
(A) House sewer
(B) Lateral sewer
(C) Branch sewer
(D) Sewer outfall
The most dangerous pollutant in vehicular emissions is____________________?
(A) CO
(B) SO2
(C) CO2
(D) O3
For laying a sewer line in a trench of 2 m width, an offset line is marked on the ground parallel to the given centre line at a distance of___________________?
(A) 100 cm
(B) 120 cm
(C) 140 cm
(D) 160 cm
The asbestos cement pipes are generally laid___________________?
(A) Horizontally
(B) Vertically
(C) At an angle of 30°
(D) At an angle of 60°
A safety lamp when inserted in the upper portion of a manhole causes flames. It indicates the presence of______________?
(A) Carbondioxide gas
(B) Hydrogen sulphide gas
(C) Methane gas
(D) Petrol vapours
If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20°C, B.O.D. of the sewage is_________________?
(A) 50 mg/l
(B) 100 mg/l
(C) 150 mg/l
(D) 250 mg/l
A circular sewer section is preferred to because__________________?
(A) It is cheaper in construction
(B) It provides maximum area for a given perimeter
(C) It provides maximum hydraulic mean depth
(D) All the above
In a city the ratio of the drainage to sewage is 20, the percentage discharge passing through non-monsoon periods, is_____________________?
(A) 5
(B) 10
(C) 15
(D) 20
In case of sewer lines_________________?
(A) Water test is carried out to check water tightness of the joints
(B) Test for straightness is carried out with the help of a lamp and mirror
(C) Obstruction test is carried out with the help of smooth ball of diameter 13 mm
(D) All the above