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environment waste water Flashcards

1
Q

If D is the diameter of upper circular portion, the overall depth of a standard egg shaped section, is

[A].	D
[B].	1.25 D
[C].	1.5 D	@
[D].	1.75 D
[E].	2 D.
A

Because top Dia-D and Bottom Dia D/2.

Hence total depth D+D/2 = 1.5 D.

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2
Q

Assertion (A) : Discharging the effluents from the oxidation ponds just up stream of lakes or reservoirs is undesirable.

Reason (R) : The discharged algae get settled in the reservoirs and cause anaerobic decomposition and other water qualities.

A

[A]. Both A and R are true and R is the correct explanation of A @

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3
Q

If the over land flow from the critical point to the drain is 8 km and the difference in level is 12.4 m, the inlet time is

[A]. 2 hours
[B]. 3 hours
[C]. 4 hours @
[D]. 5 hours.

A 
Ti = [0.885 L^3/H]^0.385.
Where Ti = inlet time in hrs.
L = overland flow in KM.
L = 8KM.
H = 12.4m.

Therefore,
Ti = 3.999 say 4hrs.

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4
Q

A rainfall may be classified as acidic if its pH value is less or equal to

[A]. 6
[B]. 7
[C]. 5 @
[D]. 6.5

A

A rainfall may be classified as acidic if its pH value is less or equal to

[A]. 6
[B]. 7
[C]. 5 @
[D]. 6.5

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5
Q

The coagulant widely used for sewage treatment, is

[A]. alum
[B]. ferric chloride @
[C]. ferric sulphate
[D]. chlorinated copperas.

A

The coagulant widely used for sewage treatment, is

[A]. alum
[B]. ferric chloride @
[C]. ferric sulphate
[D]. chlorinated copperas.

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6
Q

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	@
[E].	0.50 m/sec.
A

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	@
[E].	0.50 m/sec.
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7
Q

The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is

[A]. 1.5
[B]. 2.0 @
[C]. 3.0
[D]. 4.0

A

For trunk sewers> 1.25 m diameter = 1.5
Main sewer upto diameter 1m = 2.
Branch sewer upto diameter .5m = 3.
Lateral sewer upto diameter .25m = 4.

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8
Q

For house drainage minimum gradient is

[A]. 1 in 60 @
[B]. 1 in 80
[C]. 1 in 10
[D]. 1 in 400

A

All above ground and below ground horizontal drainage pipes should be laid to an adequate gradient. Gradients from 1 in 40 to 1 in 110 will normally give adequate flow velocities. A gradient of 1 in 80 is suitable for commencing calculations for pipe schemes.

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9
Q

If the side of a square sewer is 1000 mm, the diameter of a hydraulically equivalent circular section, is

[A]. 1045 mm
[B]. 1065 mm
[C]. 1075 mm
[D]. 1095 mm. @

A 
Relation between square and circular sewer :-
π * D^(8/3) = 4 * b^(8/3)
D^(8/3) = 4 * b^(8/3)
D^(8/3) = 4 * 1000^(8/3)/ 3.14
D^(8/3) = 127323954.47
Or D = 127323954.47^(3/8)
So D = 1094.82 say 1095.
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10
Q

In R.C. sewer pipes, the percentage longitudinal reinforcement to the cross-sectional area of concrete is kept

[A]. 10.0
[B]. 5.0
[C]. 2.0
[D]. 0.25 @

A

In R.C. sewer pipes, the percentage longitudinal reinforcement to the cross-sectional area of concrete is kept

[A]. 10.0
[B]. 5.0
[C]. 2.0
[D]. 0.25 @

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11
Q

A rain sanitary sewer is constructed to carry

[A].	sanitary sewage	@
[B].	storm sewage
[C].	surface water
[D].	ground water
[E].	all the above
A

A rain sanitary sewer is constructed to carry

[A].	sanitary sewage	@
[B].	storm sewage
[C].	surface water
[D].	ground water
[E].	all the above
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12
Q

The clarigesters are

[A]. circular septic tanks
[B]. rectangular septic tanks
[C]. circular Imhoff double tanks with bottom hoppers
[D]. circular Imhoff double storey tanks without bottom hoppers. @

A

The clarigesters are

[A]. circular septic tanks
[B]. rectangular septic tanks
[C]. circular Imhoff double tanks with bottom hoppers
[D]. circular Imhoff double storey tanks without bottom hoppers. @

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13
Q

Maximum permissible velocity 1.5 m/sec, is adopted in drains

[A]. with beds of rocks and gravels
[B]. lined with stones
[C]. both (a) and (b) @
[D]. neither (a) nor (b).

A

Maximum permissible velocity 1.5 m/sec, is adopted in drains

[A]. with beds of rocks and gravels
[B]. lined with stones
[C]. both (a) and (b) @
[D]. neither (a) nor (b).

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14
Q

he digested sludge from septic tanks, is removed after a maximum period of

[A]. 3 years @
[B]. 3.5 years
[C]. 4 years
[D]. 5 years.

A

It is 6 months to 3 years (generally 1 year).

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15
Q

Sewer ventilating columns are generally placed at

[A]. distances 150 m to 300 m
[B]. upper ends of branch sewers
[C]. every change in the size of sewers
[D]. all the above. @

A

Sewer ventilating columns are generally placed at

[A]. distances 150 m to 300 m
[B]. upper ends of branch sewers
[C]. every change in the size of sewers
[D]. all the above. @

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16
Q

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.
A

1) Shallow manholes: These are 0.7 to 0.9 m depth, constructed at the start of the branch sewer or at a place not subjected to heavy traffic conditions. These are provided with light cover at top and called inspection chamber
2) Normal manholes:: These manholes are 1.5 m deep with dimensions 1.0 m x 1.0 m square or rectangular with 1.2 m x 0.9 m .These are provided with heavy cover at its top to support the anticipated traffic load.
3) Deep Manholes: The depth of these manholes is more than 1.5 m. The section of such manhole is not uniform throughout. The size in the upper portion is reduced by providing an offset. Steps are provided in such manholes for descending into the manhole. These are provided with heavy cover at its top to support the traffic load.

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17
Q

For design purposes, the normal rate of infiltration of ground water into the sewer, is

[A].	500 litres/km/cm
[B].	1000 litres/km/cm
[C].	1500 litres/km/cm
[D].	2000 litres/km/cm	@
[E].	2500 litres/km/cm.
A

For design purposes, the normal rate of infiltration of ground water into the sewer, is

[A].	500 litres/km/cm
[B].	1000 litres/km/cm
[C].	1500 litres/km/cm
[D].	2000 litres/km/cm	@
[E].	2500 litres/km/cm.
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18
Q

Fresh sewage may become stale in

[A].	one hour
[B].	two to three hours
[C].	three to four hours	@
[D].	six hours.
[E].	ten hours.
A

Fresh sewage may become stale in

[A].	one hour
[B].	two to three hours
[C].	three to four hours	@
[D].	six hours.
[E].	ten hours.
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19
Q

The small sewers are cleaned by

[A]. flushing @
[B]. cane rodding
[C]. wooden pills
[D]. none of these.

A

The small sewers are cleaned by

[A]. flushing @
[B]. cane rodding
[C]. wooden pills
[D]. none of these.

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20
Q

Which one of the following tests is used for testing sewer pipes :

[A]. water test
[B]. ball test
[C]. mirror test
[D]. all of these. @

A

Water to check leakage.
Ball to check obstruction.
Mirror to check the straightness of sewer.

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21
Q

It is customary to design a sewer for D.W.F. on the basis of

[A]. average demand
[B]. twice the average demand
[C]. thrice the average demand @
[D]. four times the average demand.

A

Actually for separate system = 6x DWF.

For combined system= rain + 2x DWF.

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22
Q

In septic tanks,

[A]. free board of 0.3 m may be provided
[B]. the baffles or tees are extended up to top level of scum
[C]. the clear space between the baffle top and covering slab is about 7.5 cm
[D]. the inlet is kept 30 cm below the sewage line and outlet is kept at a level 40% depth of the sewage
[E]. all the above. @

A

In septic tanks,

[A]. free board of 0.3 m may be provided
[B]. the baffles or tees are extended up to top level of scum
[C]. the clear space between the baffle top and covering slab is about 7.5 cm
[D]. the inlet is kept 30 cm below the sewage line and outlet is kept at a level 40% depth of the sewage
[E]. all the above. @

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23
Q

The algae dies out in the zone of

[A]. degradation @
[B]. active decomposition
[C]. recovery
[D]. cleaner water.

A

Algae die out in degradation zone but fish survive. Fish dies out in active decomposition zone.

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24
Q

The recommended detention period for grit chambers is

[A]. 1 minute @
[B]. 2 minutes
[C]. 3 minutes
[D]. 5 minutes

A

The detention time of 30 to 60 seconds is recommended for the grit chamber. With variation in sewage flow received at treatment plant.

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25
Q

Inter-distance between ventilation columns in a sewer line is kept

[A]. 25 to 50 m
[B]. 50 m to 100 m
[C]. 100 m to 150 m
[D]. 150 m to 300 m. @

A

Inter-distance between ventilation columns in a sewer line is kept

[A]. 25 to 50 m
[B]. 50 m to 100 m
[C]. 100 m to 150 m
[D]. 150 m to 300 m. @

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26
Q

If the peak discharge of a storm water drain (S.W. Drain) is e.xpected to exceed 150 cumecs, the free board to be provided, is

[A]. 100 cm @
[B]. 90 cm
[C]. 80 cm
[D]. 50 cm.

A

Free board = ( 2/3 of peak discharge).
= ( 2/3 x 150 ).
= 100.

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27
Q

The spacing of bars of perforations of fine screens used for the treatment of sewage, is

[A]. 2 to 3 mm @
[B]. 3 to 5 mm
[C]. 5 to 8 mm
[D]. 8 to 10 mm.

A

The spacing of bars of perforations of fine screens used for the treatment of sewage, is

[A]. 2 to 3 mm @
[B]. 3 to 5 mm
[C]. 5 to 8 mm
[D]. 8 to 10 mm.

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28
Q

The sludge does not contain waste water from

[A]. bath rooms
[B]. wash basins
[C]. kitchen sinks
[D]. toilets. @

A

The term “SLUDGE” is applied to waste which not contain human excreta.

Eg- wastewater from kitchen and bathrooms.

29
Q

The maximum diameter of sewers adopted in the designs is

[A]. 1.0 m
[B]. 2.0 m
[C]. 3.0 m @
[D]. 4.0 m.

A

The maximum diameter of sewers adopted in the designs is

[A]. 1.0 m
[B]. 2.0 m
[C]. 3.0 m @
[D]. 4.0 m.

30
Q

Sluge banks are formed if sewage is disposed of in

[A]. rivers
[B]. seas @
[C]. lakes
[D]. none of these

A

Sea is the correct answer. Due to seawater turbulence sludge gets deposited to banks and anaerobic decomposition takes place which results in a foul smell.

31
Q

Primary treatment of sewage consists of removal of

[A].	large suspended organic solids	@
[B].	oil and grease
[C].	sand and girt
[D].	floating materials
[E].	none of these.
A

Preliminary treatment — inorganic solids.

Primary treatment—- settlable or suspended organic solids.

Secondary tratment —– dissolved organic.

Final treatment —– pathogenic bacteria.

32
Q

In trickling filter, B.O.D. is reduced to

[A].	30 to 40%
[B].	40 to 60%
[C].	60 to 80%	@
[D].	80 to 90%
[E].	95%.
A

Low rate trickling filter - 75-80%.

High rate trickling filter - 80-95%.

33
Q

Which one of the following statements regarding septic tanks is wrong :

[A]. a gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided
[B]. the outlet invert level is kept 5 to 7.5 cm below the inlet invert level
[C]. the minimum width of septic level is 90 cm
[D]. the depth of tank is kept equal to its width. @

A

Which one of the following statements regarding septic tanks is wrong :

[A]. a gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided
[B]. the outlet invert level is kept 5 to 7.5 cm below the inlet invert level
[C]. the minimum width of septic level is 90 cm
[D]. the depth of tank is kept equal to its width. @

34
Q

In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,

[A]. is only provided
[B]. is doubled @
[C]. is trebled
[D]. is not enough.

A

In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,

[A]. is only provided
[B]. is doubled @
[C]. is trebled
[D]. is not enough.

35
Q

The maximum spacing of manholes specified by Indian standard in sewers upto 0.3 m diameter is

[A]. 20 m
[B]. 30 m
[C]. 45 m @
[D]. 75 m.

A

The spacing of manhole is recommended in IS 1742-1960.

For sewer, up to 0.3 m diameter or sewers which cannot be entered for cleaning or inspection the maximum spacing between the manholes recommended is 30 m, and 300 m spacing for pipe greater than 2.0 m diameter.

Pipe Diameter - Spacing
Small sewers - 45 m.
0.9 to 1.5 m - 90 to 150 m.
1.5 to 2.0 m - 150 to 200 m.
Greater than 2.0 m - 300 m.
36
Q

The design period in years for pumping plants, is

[A]. 1
[B]. 2 to 3
[C]. 3 to 5
[D]. 5 to 10 @

A

The design period in years for pumping plants, is

[A]. 1
[B]. 2 to 3
[C]. 3 to 5
[D]. 5 to 10 @

37
Q

If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is

[A]. 1 in 60
[B]. 1 in 100 @
[C]. 1 in 120
[D]. none of these.

A

If the diameter of a sewer is 150 mm, the gradient required for generating self cleansing velocity, is

[A]. 1 in 60
[B]. 1 in 100 @
[C]. 1 in 120
[D]. none of these.

38
Q

A nuisance is experienced in diluting water if dilution factor is less than

[A].	100
[B].	60
[C].	40
[D].	20	@
[E].	10
A

A nuisance is experienced in diluting water if dilution factor is less than

[A].	100
[B].	60
[C].	40
[D].	20	@
[E].	10
39
Q

Pick up the correct statement from the following :

[A]. Inlets are provided on the road surface at the lowest point for draining rain water
[B]. Inlets are generally provided at an interval of 30 m to 60 m along straight roads
[C]. Inlets having vertical openings, are called curb inlets
[D]. Inlets having horizontal openings, are called horizontal inlets
[E]. All the above. @

A

Pick up the correct statement from the following :

[A]. Inlets are provided on the road surface at the lowest point for draining rain water
[B]. Inlets are generally provided at an interval of 30 m to 60 m along straight roads
[C]. Inlets having vertical openings, are called curb inlets
[D]. Inlets having horizontal openings, are called horizontal inlets
[E]. All the above. @

40
Q

Pick up the correct statement from the following :

[A]. The boning rod is used for checking the levels of the sewer inverts
[B]. Manhole covers are made circular for the convenience of the cleaning staff
[C]. A manhole is classified as deep manhole if its depth is more than 1.5 m
[D]. A manhole is classified as shallow manhole if its depth is. less than 0.9 m
[E]. All the above.

A

Pick up the correct statement from the following :

[A]. The boning rod is used for checking the levels of the sewer inverts
[B]. Manhole covers are made circular for the convenience of the cleaning staff
[C]. A manhole is classified as deep manhole if its depth is more than 1.5 m
[D]. A manhole is classified as shallow manhole if its depth is. less than 0.9 m
[E]. All the above. @

41
Q

The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called

[A]. inverted syphon
[B]. depressed sewer
[C]. sag pipe
[D]. all of these.

A

[D]. all of these.

42
Q

The sewer which received discharge from two or more main sewers, is known as

[A].	
a trunk sewer	@
[B].	an outfall sewer
[C].	a main sewer
[D].	an intercepting sewer.
A

The flow line is as:-

House->Lateral->Main->Trunk->Outfall.

In between Main and Trunk, there is intercepting sewer to carry rain stormwater when the flow exceeds via a leaping weir.

43
Q

Assertion (A) : A free board of 0.3 m is provided above the top sewage line in septic tanks.

Reason (R) : It helps to accommodate the scum in the septic tank.

[A]. Both A and R are true and R is the correct explanation of A @
[B]. Both A and R are true but R is not a correct explanation of A

A

Assertion (A) : A free board of 0.3 m is provided above the top sewage line in septic tanks.

Reason (R) : It helps to accommodate the scum in the septic tank.

[A]. Both A and R are true and R is the correct explanation of A @
[B]. Both A and R are true but R is not a correct explanation of A

44
Q

In sewage, the solids in mg per litre is

[A]. 100 to 500
[B]. 500 to 1000 @
[C]. 1000 to 1500
[D]. 1500 to 2000

A

In sewage, the solids in mg per litre is

[A]. 100 to 500
[B]. 500 to 1000 @
[C]. 1000 to 1500
[D]. 1500 to 2000

45
Q

If the grit in grit chambers is 4.5 million litres per day, its cleaning is done

[A]. manually @
[B]. mechanically
[C]. hydraulically
[D]. electrically.

A

If the grit in grit chambers is 4.5 million litres per day, its cleaning is done

[A]. manually @
[B]. mechanically
[C]. hydraulically
[D]. electrically.

46
Q

The porosity of sediments in sewer pipes, is usually taken as

[A].	0.010
[B].	0.011
[C].	0.012
[D].	0.013	@
[E].	0.020
A

The porosity of sediments in sewer pipes, is usually taken as

[A].	0.010
[B].	0.011
[C].	0.012
[D].	0.013	@
[E].	0.020
47
Q

The stone ware sewers

[A]. are used for carrying sewage and drainage from houses
[B]. are manufactured from clays and shales
[C]. after casting are dried and burnt at temperature 150°C, 700°C and 1200°C
[D]. are generally provided with a water proof cover by vaporising sodium chloride
[E]. all the above.

A

all correct

48
Q

‘Cowl’ is provided at

[A]. lower end of ventilating column
[B]. upper end of ventilating column @
[C]. upper end of the manhole
[D]. first step in manhole.

A

Cowl is a chimney top constructed from chimney pipes shaped like the letter H.

49
Q

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.

A

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.

50
Q

You are asked to design sewer pipes of diameters 0.4 m to 0.9 m at maximum flow, you will assume the sewer flow running at

[A]. full depth
[B]. half full @
[C]. two third full
[D]. three fourth full.

A

It’s two-third full.

up to 0.4m - half full.

0.4 to 0.9 - two third.

Greater than 0.9m - three-fourth full.

51
Q

In the activated sludge process

[A]. aeration is continued till stability
[B]. aeration is done with an admixture of previously aerated sludge @
[C]. sludge is activated by constant stirring
[D]. water is removed by centrifugal action.

A

In the activated sludge process

[A]. aeration is continued till stability
[B]. aeration is done with an admixture of previously aerated sludge @
[C]. sludge is activated by constant stirring
[D]. water is removed by centrifugal action.

52
Q

The minimum diameter of a sewer is kept

[A].	10 cm
[B].	15 cm	@
[C].	20 cm
[D].	25 cm
[E].	30 cm.
A

The minimum diameter of a sewer is kept

[A].	10 cm
[B].	15 cm	@
[C].	20 cm
[D].	25 cm
[E].	30 cm.
53
Q

For detecting the nitrites in the sewage, the matching colour may be developed by adding

[A]. Pottassium permanganate
[B]. Sulphuric acid and napthamine @
[C]. Phenol-di-sulphuric acid pottassium hydroxide
[D]. None of these.

A

Option C is for nitrate and B is for nitrite.

54
Q

If the diameter of a sewer is 100 mm, the gradient required for generating self cleansing velocity, is

[A]. 1 in 60 @
[B]. 1 in 100
[C]. 1 in 120
[D]. none of these.

A

Diameter(mm) —— gradient.
100 —— 1 in 60.
150 —— 1 in 100.
200 —— 1 in 120.

55
Q

The laying of sewers is done with

[A].	magnetic compass
[B].	theodolite
[C].	level	@
[D].	clinometer
[E].	plane table.
A

The laying of sewers is done with

[A].	magnetic compass
[B].	theodolite
[C].	level	@
[D].	clinometer
[E].	plane table.
56
Q

The rational formula for peak drainage discharge, was evolved by

[A]. Fruhling
[B]. Lloyd David
[C]. Kuichling
[D]. All of these. @

A

The rational formula for peak drainage discharge, was evolved by

[A]. Fruhling
[B]. Lloyd David
[C]. Kuichling
[D]. All of these. @

57
Q

As compared to fresh river water, sea water contains oxygen

[A]. 10% less
[B]. 20% less @
[C]. 10% more
[D]. 20% more.

A

As compared to fresh river water, sea water contains oxygen

[A]. 10% less
[B]. 20% less @
[C]. 10% more
[D]. 20% more.

58
Q

The settlement velocity of a solid (diameter 0.5 mm, specific gravity 1.75) in water having temperature 10°C, is

[A]. 213.5 cm/sec
[B]. 313.5 cm/sec @
[C]. 413.5 cm/sec
[D]. 500 cm/sec.

A 
V = 418*(G-1)D((3T+70)/100)
Here,
specific gravity G=2.5.
the diameter of particle D=0.5mm.
temperature T=10.
Answer is 313.5cm/sec.
59
Q

Antisyphonage pipe is fitted

[A]. at the end of septic tanks
[B]. on manholes
[C]. with a W.C. trap @
[D]. at the beginning of sewer line.

A

Antisyphonage pipe is fitted

[A]. at the end of septic tanks
[B]. on manholes
[C]. with a W.C. trap @
[D]. at the beginning of sewer line.

60
Q

To maintain aerobic biological activity, the moisture content of the compost mass should be about

[A]. 45%
[B]. 50%
[C]. 55% @
[D]. 60%.

A

55 to 60

61
Q

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].	between 400 to 500
[E].	more than 500	@
A

> 500 no treatment.
350-500 - screening sedimentation.
150-350 - screening sedimentation aided with coagulation.
<150 - complete thoroughly treatment required.

62
Q

Acid regression stage of sludge digestion at a temperature 21°C extends over a period of

[A]. 15 days
[B]. 30 days
[C]. 60 days
[D]. 90 days. @

A

Acid fermentation-15 days (half month).

Acid regression-90 days (3 months).

Alkaline fermentation-30 days (1months).

Total time required for complete digestion in digestive unit=4 and half months.

63
Q

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]. Large sewers are cleaned by removing the deposited materials
[E]. All the above. @

A

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]. Large sewers are cleaned by removing the deposited materials
[E]. All the above. @

64
Q

The spacing of bars for perforations in coarse screens used for the treatment of sewage, is

[A].	20 mm
[B].	30 mm
[C].	40 mm
[D].	50 mm	@
[E].	100 mm.
A

The Correct Data is;

For Coarse Screen => 50 mm or more.
For Medium Screen => 6 mm to 40 mm.
For Fine Screen => 1.5 mm to 3 mm.

65
Q

Fresh sewage is generally

[A]. alkaline @
[B]. acidic
[C]. highly decomposed
[D]. a source of objectionable odour.

A

Fresh sewage is generally

[A]. alkaline @
[B]. acidic
[C]. highly decomposed
[D]. a source of objectionable odour.

66
Q

The formula which accepts the value of rugosity coefficient n = 0.012 to be used in Manning’s formula, is given by

[A]. Bazin
[B]. Crimp and Bruge @
[C]. William-Hazen
[D]. Kutter.

A

The formula which accepts the value of rugosity coefficient n = 0.012 to be used in Manning’s formula, is given by

[A]. Bazin
[B]. Crimp and Bruge @
[C]. William-Hazen
[D]. Kutter.

67
Q

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	@
[E].	180 cm.
A 
offset = half of trench width + 0.6m.
0ff = 1 + 0.6 =1.6m=160 cm.
68
Q

Pick up the incorrect size of stone ware sewers

[A].	52.5 cm
[B].	67.5 cm
[C].	82.5 cm
[D].	90 cm
[E].	none of these.	@
A

The diameter of the stoneware sewer is between 10 to 90 cm.
The diameter of the asbestos cement sewer is between 5 to 90 cm and length = 4 m.
The Diameter of PCC sewer = up to 60 cm.
The Diameter of precast RCC sewer pipes = up to 250 cm and length = 1 to 3 m.
The Diameter of the plastic sewer is between 5 to 15 cm.

INDIABIX (17 decks)

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