Environmental Engineering – IIProf. Rajesh Bhagat

Civil Engineering Department

Y.C.C.E.,Nagpur

B. E. (Civil Engg.) M. Tech. (Enviro. Engg.)GCOE, Amravati VNIT, Nagpur

Experience & Achievement:

Selected Scientist, NEERI-CSIR, Govt. of India.

GATE Qualified Three Times.

Selected Junior Engineer, ZP Washim.

Three Times Selected as UGC Approved Assistant Professor.

Assistant Professor, P.C.E., Nagpur.

Assistant Professor, Cummins College of Engg. For Women (MKSSS, Nagpur)

Mobile No.:- 8483002277 / 8483003474 Email ID :- rajeysh7bhagat@gmail.com

Website:- www.rajeysh7bhagat.wordpress.com

UNIT-I

1) Systems of sanitation: Conservancy and water carriage system. Patterns of

sewage collection systems.

2) Quantity of storm water and sanitary wastewater.

3) Hydraulic Design of sewers - capacity, size, grade, shapes and materials.

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UNIT-II

1) Sewer Appurtenances – manholes, street inlets, storm water overflows, inverted

siphons, flushing and ventilation.

2) Construction and Maintenance of sewers, equipment’s for maintenance & safety

equipment’s.

3) Sewage pumping.

4) House drainage systems, sanitary fitting and appliances, traps –function and

types, anti-syphonage, inspection chambers. Storm water drainage.

5) Rain water harvesting for individual houses & Different Methods.

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UNIT-III

1) Characteristics of wastewater.

2) Flow sheet of conventional sewage treatment plant.

3) Preliminary and primary treatment: Screens, Grit chambers, Primary

settling tank. Design of bar screens, grit chambers and primary settling tanks.

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UNIT-IV

1) Secondary Treatment: Principle of Biological Treatment. Activated

sludge process, Trickling Filter – Concept,

2) SD & SDB: Functioning and Basic Load Calculations. Sludge digestion,

Sludge drying beds.

3) Methods of disposal: Disposal on land and in water stream.

4) Self-purification capacity of stream.

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UNIT-V

1) Rural sanitation: Pit Privy, Aqua Privy, Bio-gas Recovery, Eco-Sanitation.

Septic tank including soak pit. Imhoff tanks.

2) Industrial Waste Water Treatment: Basic concepts of Industrial Waste Water

Treatment, flow equalization, neutralization. Common treatment alternatives for

industrial waste water.

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UNIT-VI

1) Introduction to Air Pollution,

2) Meteorological Parameters.

3) Monitoring methods.

4) Techniques of air pollution control.

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References:-

1. B.C. Punmia, Waste Water Engineering, Laxmi Publication

2. S.K. Garg, Environmental Engineering – Vol – II, Standard Publication

3. G.S. Birdie, Water Supply & Sanitary Engineering, Dhanpat Rai Pub Company

4. M.N. Rao & H.V.N. Rao, Air Pollution, McGraw Hill Publication.

5. M.J. Machghee, Water Supply & Sewage, McGraw Hill Publication.

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Course Objective:

1) To acquaint development of railway transportation in India.

2) To understand geometric design of railway tracks.

3) To know zoning laws for development of air transportation in India.

4) To study tunnel alignment and necessity of tunnels.

Course Outcome:

1) An ability to update & upgrade knowledge about transportation system in India.

2) An ability to design railway tracks & crossing.

3) An ability to avail information about development of air transportation in urban areas.

4) An ability to understand the construction of tunnel & advances in tunneling.

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SN CriteriaDistribution of Marks

(%)

1 Online Test 4

2 Class Copy / Assignment 4

3 Attendance 2

4 Mid Semester Examinations-I 15

5 Mid Semester Examinations-II 15

6 End Semester Examination 60

Grading: Grading is based on the following components that are weighted as described below:

Importance of Sanitation System:-

1) Spent water from bathroom, kitchens, basins, house washing, street washing, from industrial

processes, semi liquid waste of human and animal excreta, dry refuse of houses, etc are

produced daily.

2) If proper arrangement for collection, treatment & disposal of all waste produced are not

made, they will go on accumulating & creates such foul condition that the safety of the

structure such as building, roads will be in danger due to accumulation of wastewater in the

foundation.

3) The disease producing bacteria spread up in the stagnate water & the health of public will

be in danger.

4) All the drinkable water will be polluted.

5) Total insanitary conditions will be developed in the town.

6) It will be impossible for public to live in the cities.

7) Therefore in the interest of community or society it is most essential to collect treat &

dispose of all the waste products in such a way that it may not cause any havoc to the

people residing in the town.

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Sanitation Work or System:-

Sanitary engineering starts at the point where water supply engineering ends.

The sanitary works can be broadly classified as:

1) Collection Work

2) Treatment Work

3) Disposal Work

Collection Work:

Collecting all types of waste products of the town.

Refuse is collected separately & sewage is collected separately.

Collection work should be such that waste matter can be transported quickly & steadily

to the treatment plant.

Safe, efficient & economical.12

Treatment Work:

Sewage needs treatments before disposal so that it may not pollute the environment and

water body.

If the wastewater is not treated it will cause many harms like pollution of water supply

sources, destruction of food, fish and valuable aquatic life, creation of unpleasant sights

& atmospheric air pollution, etc.

Disposal Work:

The treated or untreated wastewater are disposed off in various ways by irrigating fields

or discharging into natural water course, etc.

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Points are to be considered before finalizing a Sanitary Project:-

1) Financial aspects:

2) Population:

3) Quality of sewage:

4) Rainfall:

5) Rate of sewage:

6) Sources of sewage:

7) Topography of area:

8) Present method of disposal:

9) Treatment Methods:

10) Trends of town development:

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Site for Sewage Treatment Works:-

1) Good foundation soil should be available for various units to rest firmly on the ground.

2) The general slope of the site should be moderate, so that flow from one unit to the other take

place by gravity only.

3) Site should be lowest level area of the town, so that sewage from entire town can be

collected by gravity only.

4) Enough area is available for future expansion.

5) Safe from flood.

6) Site should be situated on the leeward side of wind.

7) Not far way from city.

8) Subsoil water level at the site should be remain low even during monsoon.

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Sewage or Wastewater :

1) Used water or liquid waste generated by the community due to its various activities.

2) Any water or liquid that contains impurities in such a concentration that is harmful

if disposed into the environment.

3) It is 99.9% water & 0.1% solids

4) Quantity of sewage = 75 to 80 % of the water supplied

5) Lesser the supply of water greater the strength & vice-versa.

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TYPES OF WASTEWATER DEPENDING ON SOURCE OF GENERATION

Domestic wastewater:

the used water from the residential, commercial, & institutional zones of a city.

partially treated wastewater from small industries are also included

Industrial wastewater:

the liquid waste from large & medium scale industries.

vary in quantity and quality

large volume & high strength

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Collection Methods :

1) Conservancy System

2) Water-Carriage System

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Conservancy System:

Prevailing in small town or undeveloped towns.

Various types of refuse & storm water are collected, conveyed & disposed off separately by

different methods therefore it is called conservancy system.

In the past, disposal of waste from water closets was carried out manually (dry System) and

wastewater generated from kitchen and bathrooms was allowed to flow along the open drains.

Human excreta is collected separately in privies or conservancy latrines.

The liquid & semi-liquid waste are collected in separate drains of the same latrines, from

where they are removed through human agency.

After removal night soil is taken outside the town in closed animal drawn carts or trucks.

Cheaper in initial cost.

Aesthetic appearance of city can not be increased.

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Water-Carriage System:

With the development & advancement, urgent need was felt to replace conservancy system

with improved type of system, in which human agency should not be used for the collection

& conveyance of the sewage.

Water is the cheapest substance used to transport the sewage easily & effectively therefore

it is called water-carriage system.

Excremental matter are mixed up in large quantity water & are taken out from the city

through properly designed sewerage system., where they are disposed off after necessary

treatment.

Initial cost & maintenance cost is more.

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Water-Carriage System:

The old system may pose the health hazards, because of the possibilities of flies and insects

transmitting disease germs. This is avoided in new system because of transport of night soil

in close conduit. The human excreta is washed away as soon as it is produced, thus storing

is not required as required in the old system of manual disposal.

In the old system, the wastewater generated from the kitchen and bathrooms was required to

be carried through open roadside drains for disposal. This is avoided in sewerage system as

the open drains could generate bad odor when used for disposal of organic waste.

The water carriage system does not occupy floor area, as the sewers are laid underground.

Construction of toilets one above the other is possible in water carriage system and

combining latrine and bathrooms together as water closets is possible.

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Advantages of Water-Carriage System:

It is hygienic method.

No human agency is employed.

There is no nuisance & risk of epidemics is less.

It occupies less space in crowded lane.

Due to more quantity of sewage, self cleansing velocity can be obtained even at less

gradient.

Building can be designed compact as one unit.

Less area is required for disposal.

The usual water supply is sufficient & no additional water is required.

This system does not depend on manual labor every time.

Sewage after proper treatment can be used for various purposes.

Conservancy System Water Carriage System

Very cheap in initial cost.

Causes nuisance & Foul smell.

Aesthetic appearance can not be increased.

Large area require for burying excremental matter.

Storm water is carried in drains, hence no pumping.

Fully dependent on human agency.

Does not permit compact design of structure.

Disposal without any treatment may pollute the natural water course.

Requires small quantity of water.

Waste liquid reaching the disposal point is less, hence it can be disposed off without any treatment.

High initial cost.

No foul smell.

Aesthetic appearance can be increased.

Less area is required.

May or may not require pumping.

No human agency is involved.

Permits compact design of structure.

Sewage is treated up to required degree of saturation hence less or no pollution.

Requires large quantity of water.

Large quantity of sewage highly polluted in nature, it requires treatment before disposal.

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Common Terms Used in Sanitary Engineering:

Refuse: Anything rejected or left as worthless.

Sullage: Wastewater from bath rooms, kitchens, etc. & does not include human or animal

excreta.

Sewage: Liquid waste from community & includes sullage, discharge from latrines, urinals,

industrial wastewater & storm water.

Sanitary Sewage: Liquid waste of domestic & industrial places. Extremely foul in nature &

required to be disposed off very carefully.

Sewer: Underground conduits or drains through which sewage is conveyed are known as

sewers.

Sewerage: The entire science of collecting and carrying sewage by water carriage system

through sewers is known as sewerage.

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Sewerage System:

The sewerage system are classified as follows:

1) Combined System

2) Separate System

3) Partially Separate System

Combined system:

Only one set of sewers is used to carry both the sanitary & storm water.

Most suited in areas having small & evenly distributed rainfall throughout the year.

In India, this system will face the problem of maintaining self cleansing velocity in the

sewers during dry season.

No need of flushing because more self cleansing velocity is available due to more quantity

of sewage.

Rain water dilutes the sewage.

Initial cost is high as compared with separate system.

In congested areas, easy to lay one large sewer than two smaller sewers.

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Advantages of Combined System:

Where rainfall is spread throughout a year, there is no need of flushing of sewers, as self

cleansing velocity will developed due to more quantity because of addition of storm

water.

Only one set of pipe will be required for house plumbing.

In congested areas it is easy to lay only one pipe rather than two pipes as required in

other systems.

Disadvantages of Combined System:

Not suitable for the area with small period of rainfall in a year, because dry weather flow

will be small due to which self cleansing velocity may not develop in sewers, resulting in

silting.

Large flow is required to be treated at sewage treatment plant before disposal, hence

resulting in higher capital and operating cost of the treatment plant.

When pumping is required this system is uneconomical.

During rains overflowing of sewers will spoil or endanger public health.

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Separate System:

1) Two sets of sewers are used, one for carrying sewage & other for carrying storm water.

2) Sewage is carried to the treatment plant & storm water is discharged directly into natural

outlet.

Advantages:

1) Load on treatment units becomes less.

2) Natural water is not unnecessarily polluted.

3) Small size sewers are required.

4) Storm water discharged into natural streams.

5) Economical when pumping is needed for lifting of sewage.

Disadvantages:

1) Cleaning of sewer are difficult as they are small in size.

2) Maintenance cost is high.

3) Self cleansing velocity is not easily achieved due to small quantity of sewage.

4) Storm water sewers operates only during monsoon hence becomes dumping place for

garbage during summer-winter & may thus be choked.

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Partially Separate System:

1) Part of the storm water especially collected from roofs and paved courtyards of the

buildings is admitted in the same sewer along with sewage from residences and

institutions, etc. The storm water from the other places is collected separately using

separate conduits.

Advantages:

1) Economical and reasonable size sewers are required.

2) Work of house plumbing is reduced as rain water from roofs, sullage from baths and

kitchen, etc. are combined with discharge from water closets.

3) Flushing of sewers may not be required as small portion of storm water is allowed to enter

in sanitary sewage.

Disadvantages:

1) The quantity of storm water admitted in sewer may increase the load on pumping and

treatment units.

2) Self-cleansing velocity may not develop in the sewers in dry weather.

Separate System Combined System

The quantity of sewage is to be treated is very less, because no need to treat the storm water.

Suitable for places where more intensity of rainfall takes place.

Difficult to use in narrow street.

In case of pumping of sewage, it is less costly.

Two sewer line of small size is needed & it is not costly as compare to combined system.

Treatment of sewage and storm water are to be done, so it is very costly method.

Suitable for places where less intensity of rainfall takes place throughout the year.

Suitable for narrow street.

Pumping of sewage is costly because sewage is having storm water.

Only one line of sewer of big size is required, hence more costly.

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Patterns of Collection System:

1) Perpendicular Pattern

2) Interceptor Pattern

3) Radial Pattern

4) Fan pattern

5) Zonal Pattern

The patterns of collection system depend upon:

1. The topographical and hydrological features of the area.

2. The location and methods of treatment and disposal works.

3. The type of sewerage system employed, and

4. Extent of area to be served.

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1) Perpendicular pattern:

The main trunk sewer are laid perpendicular to natural water course.

The shortest possible path is maintained for the rains carrying storm water and sewage

Suitable for separate system and partially separate system.

Not suitable for combined system, because treatment plant is required to be installed at

every point of outlet; otherwise it will pollute the water body where the sewage is

discharged.

Fig. 1.1 Perpendicular Pattern (1)

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2) Interceptor pattern:

Improvement over the perpendicular pattern.

Sewers are intercepted with large size sewers which are laid along the water course.

Interceptor carries sewage to a common point, where it can be disposed off with or without

treatment.

Overflow or Storm regulators may be provided to handle very large flow or storm water.

Fig. 1.2 Interceptor Pattern (1)

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3) Radial Pattern:

Sewers are laid radially outwards from the centre of city, hence this pattern is called as

radial pattern.

It is suitable for sewage disposal by land.

More number of disposal works is required.

Fig. 1.3 Radial Pattern (1)

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4) Fan Pattern:

Single treatment plant is located at a certain common point & the entire sewage flow is

directed towards this point.

Suitable for a city situated at one side of the natural water body, such as river.

Number of converging main sewers and sub-mains are used forming a fan shape.

The drawback in this pattern is that larger diameter sewer is required near to the treatment

plant as entire sewage is collected at common point.

For new development of the city the load on existing treatment plant increases hence

restriction will have to be imposed on such development..

Fig. 1.4 Fan Pattern (3)

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5) Zone Pattern:

City is divided into suitable zones and separate interceptor is provided for each zone.

More numbers of interceptors are provided in this pattern.

Suitable & economical for sloping area than flat areas.

Fig. 1.5 Zone Pattern (3)

Factors to be Considered in the Determination of the Quantity of Storm Water

or Sewage:

1) Intensity & Duration of Rainfall:

2) Topography of Watershed:

a) Extent of Catchment Area:

b) Shape of the Area:

c) Slope of the Area:

d) Nature of Soil:

e) Number of Available Ditches in the Area:

3) Atmospheric Temperature, Wind & Humidity:

Storm Water:

The quantity of storm water can be calculated by following two methods Rational & Empirical

Formulae:

1) Rational Method:

2) Q = ( C x R x A ) / 360

Where, Q = Quantity of storm water in m3/s

R = Intensity of rainfall, mm/hour

A = Drainage area in hectors

C = Runoff coefficient, 0.1 - 0.95

Overall runoff coefficient for different types of surface area,

C = ((A1 x C1 + A2 x C2 + …. +An x Cn) / (A1 + A2 + …. +An))

A1, A2, An are the different area & C1,C2, Cn are their runoff coeff. Respectively.

Que.1 The surface on which the rainfalls occurs consists of roots and pavements 40%

(C1=0.8), lawn and gardens 60% (C2=0.2), calculate the runoff coefficient. If the total

area of the district is 2 hectors and the intensity of rainfall is 50mm, what is the rate of

runoff of the district.

C = (0.32A + 0.12 A ) / A = 0.44

Q = (2 x 0.44 x 50 ) / 360 = 0.122 m3/s

Storm Water:

The quantity of storm water can be calculated by following two methods Rational & Empirical

Formulae:

Empirical Formulae Method:

All empirical formulae are only applicable under certain condition. Suitable for a particular

region after long practical, experience & collection of data.

1) Burkli- Zeiglar Formula: Q = (( C I A)/141.58) 4√(S/A)

2) McMath’s Formula: Q = (( C I A)/141.58) 5√(S/A)

3) Fuller’s Formula: Q = C M 0.8 / 13.23

4) Fanning’s Formula: Q = 12.8 M 5/8

5) Talbot’s Formula: Q = 22.4 M ¼

Q = Runoff in m3/s

I = intensity of rainfall, cm/hr ( R = rainfall intensity )

S = slope of the area, meter per thousand meter

A = Drainage area in Hectors & M = Drainage area in Km2

C = Runoff coefficient or I = Impermeability Factor

Quantity of Sanitary Sewage:

The quantity of sanitary sewage is mainly affected by the following factors:

1) Rate of water supply

2) Population

3) Type of area served as residential, commercial, industrial, etc.

4) Ground water infiltration.

Determination:

1) Quantity of sanitary sewage should be equal to the quantity of water applied by water

works but actually subtraction are done due to leakage or water being consumed in drinking,

cooking, sprinkling, etc.

2) After doing all calculation, addition & subtraction, Quantity of sanitary sewage = 75 to 80

% of the total water supplied.

Variation in Quantity of Sanitary Sewage:

1) Practical average never flow in sewer, it continuously varies from hour to hour of the day

and season to season.

2) The design of sewer should be done for the maximum possible flow.

3) Fluctuation is due to outcome certain local condition, habits, customs, holidays, season, etc.

4) Self cleansing velocity should be maintained in the case of minimum flow.

Variation in Sewage Flow

Typical hourly variations in sewage flow

Maximum daily flow = Two times the annual average daily flow

(representing seasonal variations)

Maximum hourly flow = 1.5 times the maximum daily flow

(accounting hourly variations)

= Three times the annual average daily flow

Minimum daily flow = 2/3 Annual average daily flow

Minimum hourly flow = ½ Minimum daily flow

= 1/3 Annual average daily flow

Design Period

The future period for which the provision is made in designing the capacities of the

various components of the sewerage scheme is known as the design period.

The design period depends upon the following:

1) Ease and difficulty in expansion,

2) Amount and availability of investment,

3) Anticipated rate of population growth, including shifts in communities, industries

and commercial investments,

4) Hydraulic constraints of the systems designed, and

5) Life of the material and equipment.

1. Laterals less than 15 cm diameter : Full development

2. Trunk or main sewers : 40 to 50 years

3. Treatment Units : 15 to 20 years

4. Pumping plant : 5 to 10 years

Important Factors Considered for Selecting Material for Sewer

a. Resistance to corrosion

b. Resistance to abrasion

c. Strength and durability

d. Weight of the material

e. Imperviousness

f. Economy and cost

g. Hydraulically efficient

Materials for Sewers

Asbestos Cement Sewers

Plain Cement Concrete or Reinforced Cement Concrete

Vitrified Clay or Stoneware Sewers

Brick Sewers

Cast Iron Sewers

Steel Pipes

Ductile Iron Pipes

Plastic sewers (PVC pipes)

Surface Drain Section:

1) Rectangular Surface Drain

2) Semicircular Surface Drain

3) U-Shaped Surface Drain

4) V-Shaped Surface Drain

Shapes of Sewer Pipes

(a) Standard Egg Shaped Sewer ( b) New/ Modified Egg shaped Sewer

(c) Horse shoe sewer section (d) Parabolic section

Fig. Shapes of Sewer

(e) Semi-elliptical section ( f) Rectangular Sewer

(g) U-shaped section (h) Semi-circular Section

(i) Basket-Handle Section

Fig. Shapes of Sewer

Egg Shaped Sewer:-

1) The depth of these sewer is 1.5m times of their width.

2) Constructed at site & made of concrete and brick arch with special invert at bottom

or of RCC.

3) Better hydraulic property than circular with low discharge.

4) Used in both combined & separate system.

5) Most suitable for combined system bcoz gives self cleansing velocity even in DWF.

6) Equally suitable for separate system bcoz easily accommodate the flow of sewage

with the development of the town.

7) Disadvantages are construction is difficult, less stable & requires good masonary

backing.

Que. 2 Calculate the velocity of flow in a sewer of diameter 1.5m. The sewer is

laid at a gradient of 1 in 550m. What will be the discharge through this sewer

when running one-half full? Assume m = 0.012 in Mannings formula.

According to Manning’s formula v = (1 / m) x r(2/3) x S(1/2)

Hydraulic Mean Depth, r = (A/P) = d/4 for circular sewer running one half full

r = 1.5 / 4 = 0.375m

S = slope or gradient = 1 / 550

Putting values in Manning’s formula,

v = (1/0.012) 0.375(2/3) (1/550)(1/2)

v = 1.84 m/s

Q = A x v

Q = ½ x ((∏ x d2) / 4 ) x (1.84)

Q = 1.63 m3 / s

Que. 3 Determine the velocity of flow in a circular sewer diameter 120 cm, laid

on slope of 1 in 700, while flowing full. Assume m = 0.013 in Manning’s

formula.

r = 0.3m

v = 1.302 m/s

Q = 1.47 m3/s

Que. 4 A sewer district has the Area = 5 hectors, Impermeability factors = 0.5, Design

intensity of rainfall = 40 mm/hr, Density of population = 500 person per hectors, Average

rate of water supply = 200 lpcd.

Determine the sanitary sewage and storm water flow for design of sewer.

Sanitary Sewage Flow:

Average rate of water flow = 200 lpcd

Assuming peak factor = 3

Area, A = 5 hector

Population Density, Pd = 500 person per hector

Q = 3 x A x Pd x flow rate

Q = 3 x 5 x 500 x 200

Q = 1.5 x 10 6 Lit/Day

Q = 0.0174 m3 / s

Strom Water Flow:

Q = (A x C x R) / 360

Q = (5 x 0.5 x 40) / 360 = 0.278 m3 / s

Que. 5 Design the section of a combined circular sewer when area to be served = 150

hectares, population of locality = 50000, Max permissible velocity = 3.2 m/s, time of entry

= 5 minutes, time of flow = 20 minutes, Rate of water supply = 270 liters/day/capita &

Impermeability factor = 0.45.

Sanitary Sewage Flow:

Assuming peak factor = 3.0

Maximum flow, Q = (3.0 x 270 x 50000 x 10-3 ) / (24 x 60 x 60) = 0.4687 m3 / s

Strom Water Flow:

Time of Concentration = 5 + 20 = 25 Minutes

Intensity of Rainfall, R = ( a / (t + b))

when time conc. 20 to 100 minutes, a=760 & b= 20

R = (760 / (25 + 20)) = 16.89 mm/hr

Q = (A x C x R) / 360

Q = (150 x 0.45 x 16.89) / 360 = 3.167 m3 / s

Combined Discharge = 0.4687 + 3.167 = 3.6357 m3 / s

Q = A x v A = Q / v A = 3.6357 / 3.2 = 1.136 m2

Diameter of sewer, D = √((A x 4) / ∏ ) = 1.2m

Que. 6 Design a storm sewer when area to be distributed = 5 hectors, effective

impermeability factor = 0.4 & time of concentration = 20 minutes. Determine size and

grade of the sewer if velocity is to be maintained 1 m/s. Rainfall intensity is given by

R = (a) / ( b + t ) Take a = 750, b = 10 & m = 0.015.

Strom Water Flow:

Time of Concentration = 20 Minutes

Intensity of Rainfall, R = (a) / ( b + t )

R = (750 / (10 + 20)) = 25.0 mm/hr

Q = (A x C x R) / 360

Q = (5 x 0.4 x 25) / 360 = 0.139 m3 / s

Q = A x v A = Q / v A = 0.139 / 1 = 0.139 m2

Diameter of sewer, D = √((A x 4) / ∏ ) = 0.42 m

According to Manning’s formula v = (1 / m) x r(2/3) x S(1/2)

v = (1 / 0.015) x (D/4)(2/3) x S(1/2)

1 = (1 / 0.015) x (0.42/4)(2/3) x S(1/2)

S = 8.6 x 10 -3 1 in 220m

TYPICAL QUESTIONS

1) Define sewage, sewer & sewerage System? Explain in brief the data required in the planning of sewerage

system?

2) Explain with neat sketches different shapes of sewer?

3) Draw a neat sketch of egg shape sewer & state advantages of disadvantage of it?

4) What do you understand by “sewage collection system’? Explain the various patterns of collection system?

5) How do you determine sewage production from city? Explain the various types of pipes used in ‘Municipal

Sewerage System’?

6) What should be the characteristics of material to be used for sewers?

7) Describe the conservation system & water carriage system of sanitation with merits and demerits?

8) What do you understand by ‘fluctuation in per capita sewage Production’? State and explain the effects of

these fluctuations in the design of sewage treatment plant?

9) Explain the rational method for estimating storm water?

10) What is Dry Weather Flow? Write briefly about the factors affecting DWF?

11) Design a suitable circular sewer to carry 1200 LPS of sewage. The sewer is running half full at a slope of 1

in 600. Assume manning’s constant is 0.012.

12) If the total area is 5 hectares & the intensity of rainfall is 50 mm/hr, calculate coefficient of runoff. Assuming

following data,

Type of Area % of Total Area Runoff CoefficientRoofs & Pavements 40% 0.85Lawns & Gardens 40% 0.20Ground Surfaces 20% 0.10