dr. mahalingam college of engineering & technology, pollachi – … · 2018. 7. 28. · dr....

Dr. Mahalingam College of Engineering & Technology, Pollachi – 642 003 (An Autonomous Institution affiliated to Anna University)

Department of Civil Engineering 16CET55 - ENVIRONMENTAL ENGINEERING II

QUESTION BANK AY 2018 – 2019 BATCH 2016 VTH SEMESTER

16CET55 - ENVIRONMENTAL ENGINEERING II

UNIT-1

PLANNING FOR SEWERAGE SYSTEMS

1) The liquid waste originating from residential and industrial buildings are collectively called

a. domestic sewage

b. combined sewage

c. sanitary sewage

d. none of these

2) The sewer which transports the sewage to the point of treatment is called

a. house sewer

b. main sewer

c. outfall sewer

d. none of these

3) A combined sewerage system , collectively carries

a. domestic and industrial sewage

b. storm and domestic sewage

c. storm and industrial sewage

d. storm and sanitary sewage

4) The sewerage system originates from

a. outfall sewer

b. main sewer

c. house sewer

d. none of these

5) A sewer which receives the discharge from a number of independent houses , is called

a. house sewer

b. intercepting sewer

c. lateral sewer

d. none of these

6) A sewer pipe carrying sewage from a building to the point of its immediate disposal is called

a. intercepting sewer

b. lateral sewer

c. house sewer

d. none of these





7) When rainy season is confined to a few months, like that in India, the preferred sewerage system

would be

a. combined system

b. separate system

c. partially separate system

d. none of these

8) The suitable system of sanitation for an area having uniformly distributed mild rains through the

year like that in England is

a. Combined system

b. Separate system

c. Partially combined system

d. Partially separate system

9) The water carriage system of collection of waste products is preferred to dry conservancy system,

because

a. Cheap initial cost

b. No treatment required before disposal

c. More hygienic in nature

d. Easier to maintain

10) The water coming from kitchens and bath rooms is popularly known as

a. Domestic sewage discharge

b. Sludge discharge

c. Drainage discharge

d. None of these

11) In a city drainage system, having drainage to sewage ratio as 20 , the peak dry weather flow

would amount to

a. 20% of the design discharge

b. 5% of the design discharge

c. slightly less than 5% of the design discharge

d. slightly more than 5% of the design discharge

12) For the design of sewrs in India, the percentage of sewage discharge, is assumed as

a. 25 - 30% of water supplied from water works





b. 75 - 80% of water supplied from water works

c. 100% of water supplied from water works

d. none of these

13) The sewer pipes have to be designed and checked for

a. only maximum flow

b. only minimum flow

c. both maximum and minimum flows

d. none of them

14) Sewage treatment works are normally designed for a design period of

a. 40 - 50 years

b. 30 - 40 years

c. 15 - 20 years

d. 5 - 10 years

15) Sewage pumping plants are normally designed for a design period of

a. 40 - 50 years

b. 30 - 40 years

c. 15 - 20 years

d. 5 - 10 years

16) For indian cities , like Delhi or Calcutta, the per capita sewage production may be of the order of

a. 500 litres

b. 200 litres

c. 100 litres

d. None of these

17) The peak design flows, expressed as number of times their average values, will be

a. greater for smaller lateral sewers

b. greater for larger trunk sewers

c. equal for all sizes and types of sewers

d. none of the above

18) The ratio of maximum daily sewage flow to the average daily sewage flow for sewer mains of 0.5

to 1 m diameter, is generally taken as

a. 1.5

b. 2





c. 3

d. None of these

19) The ratio of maximum daily sewage flow to the average daily sewage flow for trunk sewers, above

1.25 m diameter, is generally taken as

a. 1.5

b. 2

c. 3

d. 4

20) The ratio of maximum daily sewage flow to the average daily sewage flow for small sewers and

laterals up to 0.25 m diameter, is generally taken as

a. 1.5

b. 2

c. 3

d. 4

21) The ratio of maximum daily sewage flow to the average daily sewage flow for branch sewers up

to 0.5 m diameter, is generally taken as

a. 1.5

b. 2

c. 3

d. 4

22) The ratio of minimum hourly flow to the average flow of sewage is

a. 1/3

b. ½

c. 2/3

d. 3

23) For moderate sized areas and sewers say upto 1 m in diameter , the maximum hourly drafts may

be considered as equal to

a. 1.5 times the maximum daily

b. 3 times the maximum daily

c. 1/3 times the maximum daily

d. none of the above





24) The peak flow for the design of sewers , has been conected to the average flow and the

population of the city in thousands , by an empricial relation, given by

a. Q = [(18+(SQR(P)))/(4+(SQR(P)))]*Qav

b. Q = [(4+(SQR(P)))/(18+(SQR(P)))]*Qav

c. Q = [(18+P)/(4+(SQR(P)))]*Qav

d. none of these

25) Point out the wrong statement , in the following assumptions, generally made in the design of

moderate sized sewers

a. average daily flow = annual average daily flow

b. maximum daily flow = 2 average daily flow

c. maximum hourly flow = 3 average daily flow

d. none of them

26) The minimum and the maximum diameter of sewers, generally adopted in the designs, may be

a. 15 cm and 100 cm

b. 15 cm and 300 cm

c. 25 cm and 450 cm

d. 60 cm and 300 cm

27) The rational formula for evaluating peak drainage discharge , can be safely applied to catchments

up to

a. 25 Hectares

b. 500 Hectares

c. 2000 Hectares

d. up to any limit

28) The value of the coefficient of runoff for paved areas is of the order of

a. 0

b. 0.5

c. 0.9

d. >1

29) The value of the coefficient of runoff for perfectly impervious areas is of the order of

a. 0

b. 0.5

c. 1





d. Infinity

30) Critical rainnfall intensity woyld always be ____________ the hourly rainfall value, if Tc excedd 1

hour

a. more than

b. less than

c. equal to

d. slightly more than

31) The rational formula for peak drainage discharge computations was evolved by

a. Kuichling

b. Fruhling

c. Lloyd David

d. All of them

32) If the overland from the critical point to the mouth of a drain is 12 km and the difference in levels

between theses points is 14.5 m , then the inlet time would be of the order of

a. 2 hours

b. 4 hours

c. 6 hours

d. 8 hours

33) The drainage discharge of a town of 16 hectares area, consisting of 40% hard paved (k = 0.8),

30% unpaved(k= 0.2), and remaining as wooded (k= 0.1) , with a mx rain intensity of 5 cm/hr,

would be computed by rational formula as equal to

a. 0.91 cumecs

b. 0.091 cumecs

c. 9.1 cumecs

d. none of these

34) The appropriate percentage of water in sewage is

a. 90%

b. 99%

c. 99.9%

d. 99.99%

35) The specific gravity of sewage is

a. 0





b. Slighlt less than 1

c. Equal to 1

d. Slightly greater than 1

36) Pick up the incorrect statement

a. Aerobic bacteria flourish in the presence of oxygen

b. Anaerobic bacteria flourish in the absence of oxygen

c. Facultative bacteria flourish in the presence as well as absence of oxygen

d. None of the above

37) Well oxidized sewage will contain nitrogen, largely in the form of

a. Nitrites

b. Nitrates

c. Free ammonia

d. All of these

38) Partially oxidized stale sewage will contain nitrogen mainly in the form of

a. Nitrites

b. Nitrates

c. Free ammonia

d. A and c

39) Well oxidized sewage will contain sulphur largely in the form of

a. Sulphites

b. Sulphates

c. Hydrogen sulphide

d. All of these

40) Gases , which are generally evolved during aerobic decomposition of sewage are

a. CO2+NH3+H2S

b. CO2+NH3+H2S+ CH4

c. CO2+NH3 + SO2

d. CO2+NH3 + SO2+ CH4

41) Gases , which are generally evolved during anaerobic decomposition of sewage are

a. CO2+NH3+H2S

b. CO2+NH3+H2S+ CH4

c. CO2+NH3 + SO2





d. CO2+NH3 + SO2+ CH4

42) Temperature variations affect the

a. Biological activity of bacteria in sewage

b. Viscosity of sewage

c. Solubility of gases in sewage

d. All the above

43) 1000kg of sewage is estimated to contain, approximately, total solids, equal to

a. 0.5 – 1 kg

b. 2 – 5 kg

c. 5 – 10 kg

d. 10 – 20 kg

44) Imhoff cone is used to measure in sewage

a. Total soilds

b. Total organic solids

c. Total inorganic solids

d. Settelable solids

45) The pH of fresh sewage is usually

a. <7

b. >7

c. = 7

d. = 0

46) Acidity of sewage is indicated by a pH value of

a. <7

b. >7

c. = 7

d. = 14

47) pH = 3 when compared to pH = 5 will be more acidic by

a. 2 times

b. 20 times

c. 100 times

d. None of them

48) pH = 4 when compared to pH = 7 will be more acidic by





a. 3 times

b. 300 times

c. 1000 times

d. None of them

PART-B

1. Define Population Equivalent

2. Define (a) SULLAGE (b)MINAS

3. Define Sewerage

4. List the two types of Sewage System

5. List the components of sewerage system

6. Define peak drainage discharge

7. Mention the impacts of nutrients on water bodies

8. State the effect of oxygen demanding waste on water bodies

9. Mention the effect of oxygen demanding waste on water bodies

10. Enumerate the sources of waste water

11. State the reason why analyses BOD and COD usually give different results for the same waste

water

12. Define suspended solids and state the effect of suspended solids on water bodies

13. Name sewage characteristics with which organic matter concentration is

expressed

14. Distinguish between “dry weather flow” and “wet weather flow”

15. Explain the meaning and significance of time of concentration

16. Distinguish between “self-cleansing velocity” and “Non scouring velocity”

17. Define BOD (Biochemical oxygen demand), COD (Chemical oxygen demand)?

18. Define critical rainfall duration

19. Define intensity of rainfall

20. State the necessity of waste water characterization

21. State the effluent standards for any four parameters recommended by the pollution control board

22. State the five parameters of effluent standards for sewage disposal into inland surface water

bodies

23. Brief the characteristics of sewage from south Indian cities

24. State the necessity of legal requirements for effluent disposal of sewage

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25. Differentiate sewage, sullage and garbage

26. List the factor influencing the fixing of design period

27. State composition of sewage

PART-C

1. Explain the estimation of storm runoff and the factors influencing it

2. List the effects of sewage on environment

3. Explain storm water flow estimation

4. Explain different characteristics and composition of sewage

5. Explain various factors influencing Dry weather flow

6. A city with population of 1,00,000 has an area of 100 hectares. Find the D.W.F and storm water

flow for the sewer line for the following data: rate of water supply 200 LPCD, average runoff

coefficient for the entire area 0.5, time of concentration 50 min. assume 75% of water supplied

reaches the sewer.

7. Estimate the storm runoff from 10 hectares of a surface having following characteristics if the

maximum rain intensity in the area is 5 cm / hour. The area distribution (%of total ) is 30 , 10 , 5,

25,25 & 5 and coefficient of runoff is 0.9,0.85,0.8,0.4,0.1,0.05 for roof, pavement, paved yards,

macadam roads, lawns and gardens and thick vegetation.

8. Explain the legal requirements and standards regarding treatment of sewage

9. State the different sources of waste water that are produced from a community. Discuss the

systems of sewerage with its merits and demerits

10. A city with a population 1,00,000 has an area of 50 square km. rate of water supply is 110 liters

per capita per day of which 80% turns into sewer. The average run off coefficient is 0.5 and

intensity of rainfall is 14.5 mm / hour. Estimate the quantity of combined sewage. Take peak factor

as 2.5

11. Enumerate and explain the physico- chemical charateristics of sewageand state their

environmental significance

12. Explain the various adverse effects of waste water , the estimation of sanitary sewage flow and

strom runoff with the different factors affecting the characteristics and composition of sewage

13. Mention the effluent standards ad prescribed by CPCB in India. List the various legal

requirements to be met before discharging any effluent in public sewers or canals or rivers.

14. Differentiate between system Separate system and combined system





UNIT-2

SEWEAGE DESIGN

PART-A

1. Laying of sewers is usually done with the help of

a. A theodolite

b. A compass

c. A plane table

d. Sight rails and boning rod

2. The diameter od a R.C.C sewer pipe is 300mm the gradient required to generate delf cleansing

velocity would be of the order of

a. 1 in 50

b. 1 in 200

c. 1 in 500

d. 1 in 1000

3. The gradient required to generate self cleansing velocity in a circular sewer of 150 mm diameter is

of the order of

a. 1 in 30

b. 1 in 100

c. 1 in 200

d. 1 in 250

4. The flow velocity in a circular sewer at minimum design discharge is about x times the full design

velocity at maximum design discharge , where x is about

a. 60%

b. 30%

c. 90%

d. 100%

5. Minimum self-cleansing velocity in sewers calculated as 0.45 m / sec for ensuring non –

settlement of 1 mm size sand and 6mm size organics, should be checked for a minimum

discharge , equal to

a. Max design discharge

b. Average discharge





c. One third max design discharge

d. Half average discharge

6. Sewer pipes of diameter less than 0.4 m are designed at maximum flow, to be running at

a. Full depth

b. Half depth

c. Two third depth

d. Three fourth depth

7. Sewer pipes of diameter less than 0.4 to 0.9 m are designed at maximum flow, to be running at

a. Full depth

b. Half depth

c. Two third depth


8. Main trunk sewers, larger than 0.9 m in diameter are designed due to ventilation considerations at

maximum discharge running at

a. Full depth

b. Half depth

c. Two third depth


9. The most suitable section of a sewer in a separate sewerage system is

a. Rectangular

b. Circular

c. New egg shape

d. Parabolic

10. The most suitable section of a sewer in a combined sewerage system is

a. Rectangular

b. Circular

c. New egg shape

d. Parabolic

11. An egg shaped sewer when compared to a circular sewer is

a. Economical

b. More stable

c. Easier to construct





d. Provides better self-cleansing velocity at low discharges

12. The flow velocity in a sewer does not depend on

a. Its grade

b. Its length

c. Its hydraulic mean depth

d. Its roughness

13. The effect of increasing the diameter of a sewer on the self-cleansing velocity is

a. To increase it

b. To decrease it

c. Not to cause any effect

d. To cause some effect

14. In a circular sewer of diameter D, if the depth of flow is oneforth D the wetted perimeter will be

equal to

a. 3.14 D/4

b. 3.14D / 2

c. 3.14D/3

d. None of the above

15. For trunk and outfall sewers, the type of section used to be preferred in olden days , was

a. Horse shoe shaped

b. Parabolic shaped

c. Egg – shaped

d. Semi- elliptical shaped

16. The most prominent force , acting on the underground sewers pipes , would be

a. Compressive force

b. Tensile force

c. Bending force

d. All of these

17. The longitudinal reinforcement on R.C sewer pipes is x% of the cross sectional area of concrete ,

where x is

a. 0.125

b. 0.25





c. 2.5

d. 25

18. Branch and main sewers are widely made of

a. R.C.C

b. P.C.C

c. Glazed stone ware

d. Cast iron

19. House connections and lateral sewers are widely made of

a. R.C.C

b. P.C.C

c. Glazed stone ware

d. Cast iron

20. Stoneware pipes are generally not used for sewer mains because they are

a. Weak in compression

b. Weak in tension

c. Hydraulically less efficient

d. Less resistant to organic corrosion

21. The best sewer material to resist hydrogen sulphide corrosion is

a. R.C.C

b. Brick masonry

c. Glazed stoneware

d. Asbestos cement

22. Sewers are generally laid, starting from their

a. Off take point

b. Outfall point

c. Mid-point

d. Any point along the alignment

23. Sheeting and branching of excavation trench for laying sewers , will be more a necessity in

a. Clayey soil

b. Silty soils

c. Sandy soils

d. Quick sands





24. Testing of sewer pipes may involve

a. Water test

b. Mirror test

c. Ball test

d. All the above

25. For joining smaller sewer pipes of diameter less than 0.6 m or so, the preferable joint is

a. Spigot and socket joint

b. Collar joint

c. Bandage joint

d. Mechanical joint

26. For joining bigger sewer pipes of diameter more than, say 0.6 m, the preferred joint is

a. Socket and spigot joint

b. Collar joint

c. Bandage joint

d. Mechanical joint

27. Asbestos cement pipes are normally joined by using

a. Ball and spigot joint

b. Simplex joint

c. Lock joint

d. None of these

28. The equipment used for checking the levels of the sewer inverts is

a. Dumpy level

b. Boning rod

c. Theodolite

d. None of these

29. A manhole is generally classified as deep manhole, if its depth is more than

a. 0.9 m

b. 1.2 m

c. 1.5 m

d. 2 m

30. A manhole is generally classified as shallow manhole, if its depth is less than

a. 0.9 m





b. 1.2 m

c. 1.5 m

d. 2 m

31. The maximum spacing of manholes on sewers , having diameter more than 1.5 m is

a. 75 m

b. 150m

c. 200m

d. 300m

32. For very small sized sewers, of say upto 0.3m diameter, the maximum manhole spacing, specified

by Indian standards is

a. 30 m

b. 45 m

c. 75 m

d. 100 m

33. Cleanouts helps in

a. Admitting sewage into the sewer

b. Cleaning the sewer

c. Inspecting the sewer

d. None of these

34. When a sewer line is dropped below the hydraulic gradient line to pass it through an obstruction,

the arrangement is known as

a. Inverted syphon

b. Sag pipe

c. Depressed sewer

d. All of these

35. Of the following the most effective type of storm relief work to divert excess drainage in combined

sewers is

a. Leaping weir

b. Overflow weir

c. Siphon spillway

d. All of these

36. When a sheet of paper moistened with lead acetate, held for 5 minutes in a manhole, turns black;





then the sewer certainly contains

a. Hydrogen sulphide gas

b. Carbon dioxide gas

c. Methane gas

d. Petrol vapors

37. Extinguishing of the flame of a miners safety lamp within 5 minutes , when held at the level of

sewage in a manhole indicates in the sewer the presence of



c. Methane gas

d. Petrol vapors

38. Insertion of sfety lamp in the upper portion of a manhole , causing flames, surely indicates in the

sewer, the presence of



c. Methane gas

d. Petrol vapors

39. In a ventilating column , a cowl is provided

a. To prevent entry of foul gases

b. To prevent entry of objects

c. To prevent the exit of heat

d. For none of these

40. Ventilation columns are placed along a sewer line, at intervals of about

a. 30 – 50 m

b. 75 – 100 m

c. 150 – 300 m

d. 500 – 750 m

41. The pump, which permits the sewage solids to pass out with liquid sewage, without clogging the

pump, is a

a. Reciprocating pump

b. Centrifugal pump

c. Pneumatic ejector





d. None of these

42. A disintegrating pump, which breaks the sewage solids, while passing sewage through it, is a

special type of

a. Reciprocating pump

b. Centrifugal pump

c. Air pressure pump

d. None of these

43. a cylindrical ejector having a height of 2 m fills after every 10 minutes with a peak sewage

discharge of 0.0146 cumecs, the diameter of the ejector could be chosen as

a. 2.5 m

b. 2 m

c. 1.5 m

d. 1 m

44. A half cuses pump, for a lift of 10 m (including losses), should have a horse power of about

a. 1

b. 3

c. 5

d. 7

PART-B

1) Define sewer appurtenances

2) Enumerate various sewer appurtenances commonly used

3) A sewer has to be designed considering both minimum and maximum velocity. Is it true or false.

Justify it

4) State the advantages of circular section of sewers

5) Mention the various pumps used to pump sewage

6) State the situations where the pumping of sewage becomes essential in sewage management

7) State the advantages of egg shaped sewer sections

8) Define trap. State its quality requirements

9) Sewers are designed for partial flow. Is it true or false .Justify it

10) List any two computer applications of design sewer

11) Enumerate the various steps involved in the layout and construction of sewers

12) Reciprocating pumps are not widely used in the sewage pumping. Is it true or false .Justify it





13) State the significance of self-cleansing velocity in sewer design

14) Mention the circumstances were manholes has to be provided in sewerage system

15) Mention any five sewer appurtenances

16) List the various types of pumps and their functions

17) Differentiate sanitary and storm sewer

18) State the requirements of the good sewer joints

19) Write the Chezy’s and Bazin’s formula for velocity of flow

20) Define hydraulic gradient of a sewer

21) Mention the different shapes of sewers

22) List the forces acting on sewer pipes

23) List the materials used for constructing sewer pipes

24) Define catch basins

25) Define Small Bore Sewer

26) List the various test that has to be done on sewer

27) Explain one pipe and two pipe system in sewerage

28) Mention the criteria to select a pump for sewage pumping

PART-C

1. Explain Laying, jointing testing of sewer pipes, state the steps involved in laying of sewer pipes

2. Explain Sewer appurtenances

3. Explain one pipe system and two pipe system

4. Determine the diameter of separate sewer running 0.7 times full at maximum discharge for a

population of 50,000 persons. Water is supplied at a rate of 140 liters per capita per day. Assume

80% of water supplied turns as sewage. Take 2.25 as peak factor and manning’s constant, N =

0.013 at all depths of flow. The permissible flow is 1 in 700.

5. A main combined sewer is designed to serve an area of 12 square km with population density of

250 persons / hectare. Average rate of sewage flow is 250 l/capita/day. Maximum flow is 100% in

excess of average together with rainfall equivalent of 15 mm in 24 hours. All which is runoff.

Determine capacity of sewer. Taking maximum velocity of flow as 3 m/s. Determine size of

circular sewer

6. Calculate the velocity of flow and discharge in circular sewer of diameter 1 m laid at gradient of 1

in 500. Use manning’s formula, N = 0.012. Assume sewer is running half full.





7. Calculate the combined flow discharge of sewage for the following data; area to be served = 150

hectares; population of the locality = 50, 000; time of entry = 5 minutes; time of flow = 20 minutes;

rate of water supply = 135 liters/ capita / day; impermeability factor = 0.45. Assume 80% of water

– supplied turns into sewer and peak factor as 1.5 (10)

8. Discuss the methods of estimation of storm water runoff (5)

9. Determine the diameter of separate sewer section running 0.7 times full at maximum discharge

for a population of 50, 000 persons. Water is supplied at a rate of 140 liters per capita per day.

Assume 80% of water supplied turns as sewage. Take peak factor as 2.25 and manning’s

constant N = 0.013 at all depths of flow. The permissible slope is 1 in 700.

10. Discuss with a neat sketch a drop manhole and indicate where it is used

11. With a neat sketch discuss various systems of plumbing used for drainage.

12. Describe the one pipe and two pipe plumbing systems. Compare them

13. The main combined sewer is to be designed to serve an area of 12 square km with a population

of 250 persons per hectare. The average rate of flow is 250 LPCD. The maximum flow is 100% in

excess of average together with the rainfall equivalent of 15 min in 24 hours, all of which are

runoff. Determine the capacity of the sewer. Taking maximum velocity of flow as 3 m/s, also

determine the size of the sewer.

dr. mahalingam college of engineering & technology, pollachi – … · 2018. 7. 28. · dr....

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