ruidp manual of design

Module 2.3: Project Design

Contents

1.0 Introduction.......................................................................................1 1.1 Steps for Design ................................................................................1

1.1.1 Demand Assessment.....................................................................1 1.1.2 Detailed Engineering Design...........................................................1

1.2 Standard Manuals for Reference...........................................................2 1.2.1 Road Projects ..............................................................................2 1.2.2 Water Supply Projects...................................................................2 1.2.3 Sewerage Projects........................................................................2 1.2.4 Solid waste Projects......................................................................2

2.0 Design of Road Projects .....................................................................2 2.1 Road width and Designs Traffic Volumes ...............................................3 2.2 Design Approach & Criteria..................................................................5 2.3 Design of Flexible Pavement ................................................................5

2.3.1 Traffic- CV/Day Annual traffic census 24 X 7.....................................5 2.3.2 Wheel loads.................................................................................5 2.3.3 Climate.......................................................................................5 2.3.4 Terrain Plain or Hilly .....................................................................6 2.3.5 Pavement Thickness .....................................................................6

2.4 Design Traffic ....................................................................................6 2.5 Design Period ....................................................................................8 2.6 CBR Value ........................................................................................8 2.7 Other Parameters ............................................................................ 13

2.7.1 Footpath ................................................................................... 13 2.7.2 Medians .................................................................................... 14 2.7.3 Verge ....................................................................................... 14 2.7.4 Parking Lanes ............................................................................ 14 2.7.5 Bus Bays................................................................................... 14 2.7.6 Kerb ......................................................................................... 15

2.8 Location and Space for Services......................................................... 15

3.0 Design of Water Supply Projects....................................................18 3.1 Water Quality and Quantity ............................................................... 18 3.2 Design Period .................................................................................. 19 3.3 Population Forecast.......................................................................... 19 3.4 Per capita water Supply .................................................................... 19 3.5 Unit Operations of Water Treatment Plant............................................ 19

3.5.1 Aeration.................................................................................... 20

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3.5.2 Coagulation and Flocculation ........................................................ 20 3.5.3 Clariflocculators ......................................................................... 22 3.5.4 Sedimentaion ............................................................................ 22 3.5.5 Filtration ................................................................................... 23 3.5.6 Slow Sand Filter ......................................................................... 23 3.5.7 Rapid Sand Filtration Plant........................................................... 25 3.5.8 Disinfection ............................................................................... 29 3.5.9 Water Treatment Plant ................................................................ 31

3.6 Quality Standards ............................................................................ 32 3.7 Distribution System.......................................................................... 36

3.7.1 Design of Pressure Pipelines......................................................... 36 3.7.2 Minimum Pipe Sizes .................................................................... 37 3.7.3 Pipe and Material of Construction.................................................. 37 3.7.4 Modified Hazen – Williams Formula ............................................... 38 3.7.5 Residual Pressure ....................................................................... 39

3.8 Case Study of Rajkot City.................................................................. 40

4.0 Design Criteria of Sewerage Projects ...............................................43 4.1 Objective........................................................................................ 43 4.2 Main Considerations ......................................................................... 43

4.2.1 Engineering Considerations.......................................................... 43 4.2.2 Environmental Considerations ...................................................... 44 4.2.3 Process Considerations................................................................ 44

4.3 Design Period .................................................................................. 44 4.4 Population Forecast.......................................................................... 45 4.5 Sewage Generation .......................................................................... 45

4.5.1 Sewage flows............................................................................. 45 4.5.2 Peak factors .............................................................................. 45 4.5.3 Self Cleansing Velocities .............................................................. 46

4.6 Flow Characteristics ......................................................................... 47 4.6.1 Velocity at Minimum Flow ............................................................ 48 4.6.2 Minimum Size of Sewer ............................................................... 48 4.6.3 Minimum Depth of cover ............................................................. 48 4.6.4 Maximum Depth of Sewer Invert .................................................. 49 4.6.5 Ground Water Infiltration............................................................. 49 4.6.6 Sewer hydraulics ........................................................................ 49 4.6.7 Material of construction ............................................................... 50 4.6.8 Joints ....................................................................................... 50 4.6.9 Type of bedding ......................................................................... 51

4.7 Sewer Appurtenances....................................................................... 56 4.7.1 Manholes .................................................................................. 56 4.7.2 Scrapper Manholes ..................................................................... 57 4.7.3 Ventilation Shafts ....................................................................... 57

4.8 Sewage Pumping Stations ................................................................. 57

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4.8.1 Types ....................................................................................... 57 4.8.2 Design Considerations................................................................. 57

4.9 Sewage Treatment Plant ................................................................... 58 4.9.1 Plant and Process Design Parameter.............................................. 58 4.9.2 Process Design Parameters .......................................................... 59

5.0 Storm Water Drainage......................................................................66 5.1 Introduction .................................................................................... 66 5.2 Design Methodology ......................................................................... 68 5.3 Design of under ground Strom Water Network ..................................... 69

5.3.1 Modified Rational Method............................................................. 69 5.3.2 Hydrograph Design Method.......................................................... 69 5.3.3 Simulation Method...................................................................... 69

6.0 Solid Waste Management .................................................................70 6.1 Key Features – MSW Rules 2000 ........................................................ 70 6.2 Composition of waste ....................................................................... 70 6.3 Collection of Municipal Solid Waste (MSW)........................................... 72 6.4 Segregation of Municipal Solid Waste.................................................. 72 6.5 Storage of Municipal Solid Waste........................................................ 73 6.6 Transport of Municipal Solid Waste ..................................................... 73 6.7 Processing of Municipal Solid Waste.................................................... 73 6.8 Disposal of Municipal Solid Waste....................................................... 74 6.9 Design System for SWM.................................................................... 74 6.10 Street sweeping............................................................................. 74 6.11 Secondary storage ......................................................................... 74 6.12 Sample Financial Estimates for implementation of Solid Waste

Management Plan.................................................................................. 74 6.13 Design Criteria of Landfill Site Selection............................................. 78 6.14 Case Study of Rajkot DPR ............................................................... 79 6.15 Environmental Settings ................................................................... 81

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1.0 Introduction

Design is a crucial aspect and should be an integral part of all the stages of a

project. In developing countries it has been experienced that evaluation reports

cite problems of poor design owing to reasons such as:

• Inclusion of components that are inappropriate to local conditions

• Underestimation of resource needs and availability

• Inadequate or inappropriate specifications

• Lack of financial contingency planning

• Improper location etc.

1.1 Steps for Design Detailed Engineering design of each component of the project based on demand

assessment and norms & standards

1.1.1 Demand Assessment Some of the components remain common for all the infrastructure services and

form the base for all projections and assumptions e.g. population, land use, site

suitability and availability and some of the components are service specific and to

be analyzed separately e.g. distribution network, sources, norms and standards.

1.1.2 Detailed Engineering Design Each component of the project needs to be designed as per norms and standards

based on the demand assessment for the project.

• Consider the equation for population forecast.

• Existing population of area can be worked out by using the census data and

based on demographic data of last 3 decades the future population to be

served by the project should be calculated using a specified population

forecasting method as per demand assessment module.

• Now considering the survey data results are obtained from investigation

analysis by which each component can be designed as per the design criteria

and norms in the respective manual approved by organization.

• The size and quantity should be worked out using standard equations

specified in the respective manuals.

• From this size and quantity the cost of the component can be worked out.

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1.2 Standard Manuals for Reference

1.2.1 Road Projects • Manual of Ministry of Road Transport and Highway (MORTH)

• Indian Road Congress (IRC codes)

• IRC 86-1983 Geometric Design for Urban Roads in Plains.

• IRC 81-1997 Flexible Road Pavements

• BIS code 2720 various parts for tests on soils

• BIS Code 2386 various parts for tests on aggregates

1.2.2 Water Supply Projects Manual on Water Supply and Treatment Plant –third edition revised - 1999

constituted by CPHEEO- Central Public Health and Environment Engineering

Organization, Ministry of Urban Development, New Delhi, G.O.I

1.2.3 Sewerage Projects Manual on Sewerage and Sewage Treatment - second edition 1993 constituted by

CPHEEO- Central Public Health and Environment Engineering Organization,

Ministry of Urban Development, New Delhi, G.O.I

1.2.4 Solid waste Projects • Municipal Solid Waste (Management and Handling) Rules, 2000

• Manual on Solid Waste Management- First edition 2000 constituted by



2.0 Design of Road Projects

In urban areas road development takes

place along existing roads, requiring

enhancement of capacity of existing roads.

The road alignments are planned at the

time of preparation of “DP” – Development

plans. Development takes place in such a

way that carving out a new alignment

becomes practically impossible. Thus only

alternative is to use available Right of Way

and provide capacity in phases. Ultimately

all the capacity is utilised and a bypass to traffic is required. Thus enough ROW

must be reserved / provided for in the development plan itself looking to the

future requirements.

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The width and layout of urban road cross-sections depend on many factors, the

chief amongst them being the classification of road, design speed and the volume

of traffic expected. Other considerations are requirements of parking lanes, bus-

bays, loading-unloading bays, occurrences of access points, volume of

pedestrians and cyclists, width of drains, location of sewer lines, electricity cables

and other public utility services. Actual width of each element should be based on

traffic volumes and other functional requirements explained in parts 6.2.1

through 6.2.11 of IRC 86-1983.

2.1 Road width and Designs Traffic Volumes The road width – carriage way, should be designed to accommodate the design

traffic volume assessed in demand assessment. This is restricted by Right of Way

provided in the development plan. Design traffic is arrived at from traffic surveys

and socio economic profile of area influenced by the road.

• The road should be designed to accommodate the peak traffic volume

computed for the end of design life.

• A design period of 15-20 years should be adopted for arterials sub-arterial

and 10-15 years should be adopted for local and Collector Street.

• A higher design period should be taken for small towns and lower period for

large cities.

• For high volume streets and busy intersections, peak hour volumes should be

used to determine the width of road.

• The design of main traffic routes in built-up areas should be based on peak

hour demands and not as in rural area on average daily traffic.

• Right of Way recommended for the various categories of urban roads are

given in table 2.1

Table 2.1: Recommended Road Widths

Classification Recommended road width in meters Arterial 50-60

Sub-Arterial 30-40

Collector streets 20-30

Local street 10-30

Source: IRC 86 -1983

The Equivalency factors for the passenger car unit (PCU) are shown in the table 2.2 below.

Table 2.2: Equivalency factors for Vehicles

Sr. No.

Vehicle Type Equivalency Factor

1 Passenger car, tempo, auto, jeep, vans, or

agricultural tractor 1.0

2 Truck, bus, agricultural tractor-trailer 3.0


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Sr. No.

Vehicle Type Equivalency Factor

3 Motor-cycle, scooter and cycle 0.5

4 Cycle-rickshaw 1.5

5 Horse drawn vehicle 4.0

6 Bullock cart 5.0

7 Hand-cart 6.0

Source: IRC 19; 2001

Tentative Capacities of Urban Roads between Intersections are presented in table

2.3 below.

Table 2.3: Tentative Capacities of Urban Roads

No of traffic lanes and widths

Traffic flow Capacity in PCUs per hour for various traffic conditions

Roads with no

frontage

access, no

standing

vehicles, very

little cross

traffic

Road with

frontage access

but no standing

vehicle and high

capacity

intersections

Roads with free

frontage

access, parked

vehicles and

heavy cross

traffic

2 –lane One way 2400 1500 1200

(7-7.5 m) Two way 1500 1200 750

3-lanes One way 3600 2500 2000

4-lane One way 4500 3000 2400

(14 m) Two way 4000 2500 2000

6-Lane One way 3600 2500 2200

(21 m) Two way) 6000 4200 3000

Source: IRC 86; 1983 Carriageway widths recommended are shown in table 2.4 below. (IRC 86; 1983)

Table 2.4: Recommended Carriageway Widths

Description Width (meters) Single lane without kerbs 3.5

2-lane without kerbs 7.00

2- lane with kerbs 7.5

3-lane with or without kerbs 10.5 / 11.0

4-lane with or without kerbs 14.0

6- lane with or without kerbs 21.0 Source: IRC 86; 1983 Note: 1. For access roads to residential areas, a lower lane width of 3 m is permissible.

Minimum width of a kerbed urban road is 5.5 m including allowance for a stalled

vehicle.


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2.2 Design Approach & Criteria Carriage of the road mostly can mostly be design by the following three layer

structure

• Bituminous surface layer(s)

• Granular Base

• Granular Sub base This structure rests on sub-grade which in turn rests on natural ground.

2.3 Design of Flexible Pavement The following sub sections describe the various variables and parameters involved

in design of flexible pavement of road as per IRC 37 - 2001.

2.3.1 Traffic- CV/Day Annual traffic census 24 X 7 For structural design, commercial vehicles are considered. Thus vehicle of gross

weight more than 8 tonnes load are considered in design. This is arrived at from

classified volume count.

2.3.2 Wheel loads Urban traffic is heterogeneous. There is a wide spectrum of axle loads plying on

these roads. For design purpose it is simplified in terms of cumulative number of

standard axle (8160 kg) to be carried by the pavement during the design life.

This is expressed in terms of million standard axles or msa.

2.3.3 Climate Temperature is an important factor affecting the performance of Flexible

pavement (Hot or Cold). Most of our country comes under hot climate. In urban

scenario, the traffic is heterogeneous. There is sizable bicycle traffic. There is

sizable pedestrian traffic. The demand for road can be estimated by a classified

volume count of traffic. This survey should be conducted for seven days

throughout – 24 x 7 surveys. All vehicle categories including non motorised traffic

like bicycles, animal driven carts etc. There should be a separate pedestrian

survey. An Origin – Destination (OD) survey to estimate preference for a

particular route may also be carried out. Locations attracting heavy traffic

demand such as Government offices, commercial centres, hospitals, educational

institutes, religious and other places of interest may be marked and traffic

generated should be estimated.

A detailed socio economic study is required for understanding and future trends.

Planning must provide for future requirements. It is usually found that the future

projections are overtaken by faster developments, people start development

faster than estimated years the grade of bitumen to be used in surface layers.

The grade of bitumen in urban scenario, the traffic is heterogeneous. There is

sizable bicycle traffic. There is sizable pedestrian traffic. The demand for road can

be estimated by a classified volume count of traffic. This survey should be


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conducted for seven days throughout – 24 x 7 surveys. All vehicle categories

including non motorised traffic like bicycles, animal driven carts etc. There should

be a separate pedestrian survey. An Origin – Destination (OD) survey to estimate

preference for a particular route may also be carried out. Locations attracting

heavy traffic demand such as Government offices, commercial centres, hospitals,

and educational institutes, religious and other places of interest may be marked

and traffic generated should be estimated.

A detailed socio economic study is required for understanding and future trends.

Planning must provide for future requirements. It is usually found that the future

projections are overtaken by faster developments. Considerations for different

climate are given in annexure 6 of IRC 37 – 2001.

2.3.4 Terrain Plain or Hilly The terrain is dependent on natural gradient available. When natural gradient is

up to 10 percent, it is known as plain terrain. When natural gradient is between

10 to 25 percent, terrain is known as rolling. When natural gradient is between

25 to 60 percent, terrain is known as hilly. And when natural gradient is more

than 60 percent, terrain is known as steep terrain.

2.3.5 Pavement Thickness Pavement Thickness Composition can be decided by using following chart

presented in figure 2.1

Figure 2.1: Pavement thickness Design Chart for Traffic1 1-10 msa

2.4 Design Traffic


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Computation of design Traffic In terms of cumulative number of standard axle to

be carried by the pavement during design life.

N = {365 X (1+r)n – 1} x A x D x F

r

Where

N = The cumulative number of standard axles to be catered for in

design in terms of million standard axles - msa.

A = Initial traffic in the year of completion of construction duly

modified as shown below.

D = Lane distribution factor

F = Vehicle damage factor, VDF

n = Design life in years

r = Annual growth rate of commercial vehicles { this can be taken as 7.5% if no

data is available}

A = P (1 + r)x

Where,

P = Number of commercial vehicle as per last count

X = Number of years between the year of last count and the year of

completion of construction

D = Lane distribution factor It is the distribution of commercial traffic over the carriageway. It should be

considered by deciding the lane of the road. Following values should be taken for

ane distribution factor. L Table 2.5: Road Sections

Description Lane Distribution

Factor (D)

Single Lane Road 1.00

Two Lane Single Carriageway 0.75

Two Lane Double Carriageway 0.40

Four Lane single Carriageway 0.40

Four Lane Double Carriageway 0.45 Source: IRC 37

F = Vehicle damage factor (VDF).

It is a multiplier to convert the number of CV of different axle load and axle

configuration to the number of standard axle load repetition.

VDF depends on vehicle configuration, axle load, terrain, type of road.

Where sufficient information of axle load is not available then the VDF value

considered are presented in table 2.6


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Table 2.6: Vehicle Damage Factor

Terrain Initial Traffic volume in terms of Commercial Vehicles per Day Rolling / Plain Hilly 0-150 1.5 0.5

150-1500 3.5 1.5

More than 1500 4.5 2.5

Source: IRC 37

In view of the concept of cumulative axle loads, it is now possible to design a

flexible pavement for a definite period.

2.5 Design Period

A design period of 15-20 years should be adopted for arterials sub-arterial and

10-15 years should be adopted for local and Collector Street. A higher design

period should be taken for small towns and lower period for large cities. For high

volume streets and busy intersections, peak hour volumes should be used to

determine the width of road...

• For Arterial & Sub arterial 15-20 years

• For collector & local road 10-15 years

• Expressway and Urban Roads - 20 Years

• N H & SH – 15 Years

• Other Roads – 10 – 15 Years

r - Traffic Growth: From the data’s available for the last five or ten years traffic

census traffic growth can be determined. In absence of adequate data, an

average value of 7.5 % per annum growth rate may be adopted.

2.6 CBR Value California Bearing Ratio (CBR) Value as per IS 2720 (Part-XVI):

• CBR is an indirect measure of the stability of sub-grade i. e. the capacity to

resist deformations under wheel loads.

• CBR value is determined by conducting the CBR test on specimen in

laboratory as per the procedure laid down in IS 2720 Part- XVI

• It is basically a penetration test.

• The CBR test is carried out in standard CBR apparatus & the standard test

procedure prescribed in accordance with IS 2720(part-XVI) as per the

requirement.


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• The material is statically compacted in three layers at MDD & OMC determined

by a standard proctor test as per IS 2720 –part:7 for light compaction or IS-

2720- part:8 for heavy compaction as per the requirement.

• The sample is subjected to 4 days soaking.

• There after a plunger of 50 mm dia. is allowed to penetrate in the material at

the rate of 1.25 mm/min.

• The required loads required causing 2.5 mm & 5.0 mm penetrations are

recorded.

• These loads are then expressed as percentages of standard/loads, which are

the loads for corresponding penetrations in standard crushed stone

aggregates.

• Higher of two values is adopted as CBR value.

As per the IS requirements three samples shall have to be tested for CBR and the

average CBR value of three samples is taken as final CBR provided the CBR value

of all three samples are within the permissible limit of variation.

CBR (Percent) Maximum Variation in CBR Values

5 +1

5 – 10 +2

10 – 30 +3

31 and above +5


Fig2.2: PAVEMENT THICKNESS DESIGN CHART FOR TRAFFIC 1-10 MSA


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Table2.7: Recommended Design for Traffic range 1-10 msa 1

PAVEMENT COMPOSITION

Bituminous Surfacing

msa for

given

CBR

Value

Total

Thickness

(mm) Wearing Course

( mm )

Binder Course

( mm )

Base

Course

Sub

base

Course

CBR 3 %

1 550 20 PC 225 435

2 610 20 PC 50 BM 225 335

3 645 20 PC 60 BM 250 335

5 690 25 SDBC 60 DBM 250 335

10 760 40 BC 90 DBM 250 380

CBR 2%

1 660 20 PC 225 435

2 715 20 PC 50 BM 225 440

3 750 20 PC 60 BM 250 440

5 795 25 SDBC 70 DBM 250 450

10 850 40 BC 100 DBM 250 460

CBR 4%

1 480 20 PC 225 255

2 540 20 PC 50 BM 225 265

3 580 20 PC 50 BM 250 280

5 620 25 SDBC 60 DBM 250 285

10 700 40 BC 80 DBM 250 330

CBR 5%

1 430 20 PC 225 205

2 490 20 PC 50 BM 225 215

3 530 20 PC 50 BM 250 230

5 580 25 SDBC 55 DBM 250 250

10 660 40 BC 70 DBM 250 300

CBR 6%

1 390 20 PC 225 165

2 450 20 PC 50 BM 225 175

3 490 20 PC 50 BM 250 190

5 535 25 SDBC 50 DBM 250 210

10 615 40 BC 65 DBM 250 260

CBR 7%

1 375 20 PC 225 150

2 425 20 PC 50 BM 225 150

3 460 20 PC 50 BM 250 160

5 505 25 SDBC 50 DBM 250 180

10 580 40 BC 60 DBM 250 230

CBR 8%


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msa for

given

CBR

Value

Total

Thickness

(mm) Wearing Course

( mm )

Binder Course

( mm )

Base

Course

Sub

base

Course

1 375 20 PC 225 150

2 425 20 PC 50 BM 225 150

3 450 20 PC 50 BM 250 150

5 475 25 SDBC 50 DBM 250 150

10 550 40 BC 60 DBM 250 200

CBR 9 % & 10 %

1 375 20 PC 225 150

2 425 20 PC 50 BM 225 150

3 450 20 PC 50 BM 250 150

5 475 25 SDBC 50 DBM 250 150

10 540 40 BC 50 DBM 250 200


Fig 2.3: pavement thickness design chart for traffic 10-150 msa


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Table 2.8: Recommended Design for Traffic range 10 – 150 msa



msa for given

CBR Value

Total Thickness

(mm)

BC (mm) DBM (mm)

CBR 2%

10 850 40 100

20 880 40 130

30 900 40 150

Base = 250

50 925 40 175

100 955 50 195

150 975 50 215

Sub base = 460

CBR 3%

10 760 40 90

20 790 40 120

30 810 40 140

50 830 40 160

100 860 50 180

150 890 50 210

Base = 250

Sub base = 380

CBR 4%

10 700 40 80

20 730 40 110

30 750 40 130

50 780 40 160

100 800 50 170

150 820 50 190

Base = 250

Sub base = 330

CBR 5%

10 660 40 70

20 690 40 100

30 710 40 120

50 730 40 140

100 750 50 150

150 770 50 170

Base = 250

Sub base = 300

CBR 6 %

10 615 40 65

20 640 40 90

30 655 40 105

50 675 40 125

100 700 50 140

150 720 50 160

Base = 250

Sub base = 260

CBR 7 %

10 580 40 60

20 610 40 90

30 630 40 110

50 650 40 130

100 675 50 145

150 695 50 165

Base = 250

Sub base = 230

CBR 8 %

10 550 40 60

20 575 40 85

30 590 40 100

50 610 40 120

Base = 250

Sub base = 200


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msa for given

CBR Value

Total Thickness

(mm)

BC (mm) DBM (mm)

100 640 50 140

150 660 50 160

CBR 9 %

10 540 40 50

20 570 40 80

30 585 40 95

50 605 40 115

100 635 50 135

150 655 50 155

Base = 250

Sub base = 200

CBR 10 %

10 540 40 50

20 565 40 75

30 580 40 90

50 600 40 110

100 630 50 130

150 650 50 150

Base = 250

Sub base = 200

2.7 Other Parameters Following other parts of the roads should be kept in mind while designing the

Road.

2.7.1 Footpath The minimum width of footpath should be 1.5 meters. They should have well

maintained surface with cross fall neither so flat as to be difficult to drain nor so

steep as to be dangerous to walk upon.

The cross fall within the range of 2.5 to 3 % should meet requirement

Table 2.9: Required Road Widths

Number of Persons per Hour. Reqd. Width Of Footpath (m)

1200 800 1.5

2400 1600 2.0

3600 2400 2.5

4800 3200 3.0

6000 4000 4.0



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2.7.2 Medians Width of median is dictated by a variety of conditions. Widths will depend on the

available right-of-way, terrain, turn lanes, drainage and determinants. Wide

medians are preferred where space and cost considerations permit. Minimum

widths of median at intersections to accomplish various purposes should be as

follows:(i) Pedestrian refuge;(ii) Median lane for protection of vehicle making

right turn, 4.0 m but 7.5 m is recommended; (iii) 9 to 12m is required for U-

turns. Absolute minimum width of median in urban areas is 1.2m; a desirable

minimums 5m.

As far as possible, the median should be of uniform width in a particular section.

However, where changes are unavoidable, a transition of 1 m to 15 to 1 in 20

must be provided. 2.7.3 Verge Verges are required between carriage way and property line not only to

accommodate. Lighting columns, traffic signs, underground services etc., but also

to provide appropriate clearance to ensure proper vehicle placement and

development of full carriageway capacity. Where road width is restricted, full

width between carriage way and property line should be paved and used for

pedestrian sidewalk/cycle track. Where possible, a minimum verge of 1 m width

should be kept. They should be suitably levelled, trimmed and provided with a

cross fall of 5 per cent if turned and 3 per cent if cobbled or surface dressed. This

should be increased if poles, kerb-height, or excessive cross fall discourage

parking close to the kerb and also where either parked vehicles frequently overlap

on to the adjacent traffic lane or the parking lane is likely to be used as a peak

hour traffic lane.

2.7.4 Parking Lanes Parking lanes may be provided on all sub- arterials and collector streets in

business and shopping areas. Parallel kerb parking should be preferred. Parking

lane width for parallel parking should be 3 m which may be reduced to 2.5 m

where available space is limited. Where additional parking capacity is desired and

sufficient carriageway width is available, angle parking may be adopted.

2.7.5 Bus Bays Busbays should not be located too close to intersections. It is desirable that they

are located 75 m from the intersection on either side preferably on the further

side of the intersection.

Busbays should be provided preferably by recessing the kerb to avoid conflict

with moving traffic. The length of the recess should be 15 m for single bus stop

with increased of 15 m for each extra bus for multiple bus stops. The taper should

be desirably 1:8 but not less than 1:6. the depth of the recess should be 4.5 m


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for single bus stop and 7 m for multiple bus stop. Suitable arrangement should be

made for drainage of surface water from busbays. Sufficient footpath should be

ensured behind the busbays.

2.7.6 Kerb It is desirable that roads in urban areas are provided with kerbs.

Kerbs may be barrier type, semi barrier type or mountable type. Appropriate

situations for use of each type are indicated below:

• Barrier type : Built up areas adjacent to footpaths with considerable

pedestrian traffic.

• Semi-barrier type : on the periphery of the roadway where Pedestrian traffic

is light and a barrier type could to reduce traffic capacity.

• Mountable type: within the roadway at canalization sections medians outer

separators and raised medians on bridges.

Each figure shows two varieties of each type of kerb with gutter and without

gutter. Kerbs with gutter should always be used at drainage edges of pavement.

2.8 Location and Space for Services Location of the various services will depends on several factors such as class of

road, the land width available, the size and type of utility lines to be

accommodated and other related factors.

Generally, a width of 5 m for services on either side of the road will be adequate

in most cases.

Other considerations needing attention in the location of utility services are given

below.

• Utility lines should be located such that it permits maintenance of the lines

with minimum interference to road traffic.

• Utility lines should be laid on uniform alignment parallel to the road centre

line.

• Accommodation of Utility Lines across Roads:

• Several methods are available for erecting for crossing depending on

situation, but in all cases the following principles should be kept in mind.

• In case of all major roads, the service lines shall be taken though ducts of

sufficient size and strength in order to facilitate future repairs addition of

lines, etc. without resorting to cutting open of the road.

• In certain situation such as crossing of a minor road, service line may be

installed without encasement. The minimum cover on top of the service line

should be 1.2m.


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Illustration:

In Ahmedabad city Navrangpura area is in plane terrain. The soil available is

having California Bearing Ratio 5 %. Traffic surveys have been carried out on

nearby road. Traffic count has been yielded a PCU figure of 3500 in the peak

hours and a Commercial Vehicle per Day (CVD) figure of 500. It is expected that

about 2000 PCU and 200 number of CVD are likely to be diverted to the new

proposed road. The road will have all residence opening directly on to the road

(free access). As there are residential units already, parking can not be

prohibited. There is cross traffic – traffic moving in al directions. The socio-

economic surveys have indicated that the traffic growth rate on the new proposed

road could be 7.5%. AMC has decided to construct new road within two years and

the design life of the road is 10 year.

What will be the ROW / CW and Crust thickness of the new proposed road?

• The problem could be solved as below.

• First the geometrical design.

• As this is an urban arterial road the ROW is to be 60 meters. (as per table no.

2.1 )

• As PCU on new road is 2000 the CW is to be four lane two way (as per table

no.2.3 )

Crust design

Present traffic 200 CVD

A = P(1+r)n

A= 200(1+ 7.5/100)2

R= 7.5%

Construction period = 2 years

A = 200(1.155625)

A= 231.25

Say 230 CVD

N = 365x {(1+r)n - 1}x A x D x F

r

N = 365 x {(1 + 7.5/100)10 – 1} x 230 x 0.40 x 3.5

7.5/100

D = 0.4 from table 2.5

F = 3.5 from table 2.6

N = 365 {2.06 – 1) x 322

.075

N = 1661090 Standard Axles

N = 1661090 / 10,00,000

N = 1.6 msa Million standard axles


Preparation of DPRs

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Say 2 msa

CBR = 5%

Total crust thickness = 490 mm

Sub base course = 215 mm

Base course = 225 mm

Surfacing course = 50 mm BM + 20 mm PC

Some typical road cross sections for widening, construction and overlay are

presented below.


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3.0 Design of Water Supply Projects The planning of water supply systems is based on basic design parameters such

as water quality and quantity, design period, area and population to be served,

per capita rate of water supply, water needs for other purposes in the area,

pressures requirements for piped water supply, water quality standards, nature

and location of facilities to be provided, the utilization of centralized or multiple

points of treatment facilities and points of water supply intake and waste water

disposal.

The following basic design parameters should be kept in mind before designing

this component

3.1 Water Quality and Quantity The water to be used for urban water supply systems may vary both in quantity

and quality as well as in the degree of treatment required; seasonally, monthly,

daily and sometimes even hourly.

Water quantity may be managed by followings method.

(a) Water Conservation

Water conservation has to be aimed at optimal use of available water resources;

prevention and control of wastage of water and effective demand management.

(b) Increased water availability and supply & demand management

Increase of water availability can be achieved through augmentation of water

resources by storing rainwater on the surface or below the surface. Water supply

management aims at improving the supply by minimizing losses and wastage and

unaccounted for water (UFW) in the transmission mains and distribution system.

Water demand management involves measures which aim at reducing water

demand by optimal utilization of water supplies for all essential and desirable

needs.


Preparation of DPRs

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3.2 Design Period For design period please refer Module 2.2: Demand assessment

3.3 Population Forecast For population forecast please refer Module 2.2: Demand assessment

3.4 Per capita water Supply For per capita water supply please refer Module 2.2: Demand assessment

3.5 Unit Operations of Water Treatment Plant The method of treatment to be employed depends on the nature of raw water

constituents and the desired standards of water quality. The unit operations in

water treatment include aeration, flocculation (rapid and slow mixing) and

clarification, filtration, disinfection, softening, deferrization, deflouridation and

water conditioning and many different combinations of these to suit these

requirements.

Figure 3.1: Typical Flow Diagram of a Water Treatment Plant

In case of ground water and surface water with storage which are well protected,

where the water has turbidity below 10 NTU and they are free from colour and

odour, plain disinfection by chlorination is adopted before supply. In surface


Preparation of DPRs

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waters with turbidity not exceeding 50 NTU and where sufficient area is available,

plain sedimentation followed by slow sand filtration and disinfection are practiced.

3.5.1 Aeration Aeration is necessary to promote the exchange of gases between the water and

the atmosphere.

3.5.2 Coagulation and Flocculation The purpose of coagulation and flocculation is to remove particulate impurities,

especially non settleable solids (particularly colloids) and colour from the water

being treated. Non-settleable particles in water are removed by the use of

coagulating chemicals.

The most commonly used coagulant is ferric alum. However, Poly Aluminium

Chloride (PAC) is also used as a coagulant. The advantages of PAC are i) it gets

properly dispersed, ii) it does not have any insoluble residue, iii) it does not affect

the settling tanks, iv) it is more effective than alum v) it requires less space (may

be about 50%). The disadvantage of PAC is that it is less effective in removal of

colour.

Flocculation basin

The objective of a flocculation basin is to produce a settled water of low turbidity

which in turn will allow reasonably long filter runs. Following points should be

considered during the operation of the flocculation basins. Where head loss

through the plant is to be conserved as much as possible and where the flow

exceeds 300 m3 / hr, mechanical mixing which is also known as flesh mixing is

desirable.

Multiple units may be provided for large plants. Normally a detention time of 30

to 60 seconds is adopted in the flash mixer.

Head loss of 0.2 to 0.6 m of water, which is approximately equivalent to 1 to 3

watts per m3 of flow per hour is usually required for efficient flash mixing.

The intensity of mixing is dependent upon the

temporal mean velocity gradient, ‘G’. This is

defined as the rate of change of velocity per unit

distance normal to a section (or relative velocity

of two flow lines divided by the perpendicular

distance between them) and has the dimensions

of and generally expressed as s-1. The turbulence


Preparation of DPRs

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and resultant intensity to mixing is based on the rate of power input to the water

and G can be measured or calculate in terms of power input by the following

expression:

Where,

G = Temporal mean velocity gradient, s-1

P = Total input of power in water, watts;

µ = Absolute viscosity of water, N.s/m2; and

Vol= Volume of water to which power is applied, m3

Two types of mechanical mixers of coagulant:-

• Rapid rotation of impellers /blades

• Mixing with the aid of a jet / impingement on a jet

• Rapid rotation of impellers /blades:

• Propeller type impellers are commonly employed in flash mixers with high

RPM speed of 400 to 1400 rpm

• Detention time should be of 30 to 60 sec. is provided.

• Power requirements 1 to 3 Watts per m3 / hr

• The ratio of impeller diameter to tank diameter is 0.2 to 0.4 and

• The ratio of tank height to diameter is 1:1 to 3:1 is preferred for proper

dispersal.

Types of Slow Mixers

1. Gravitational or Hydraulic Type Flocculators

a. Horizontal Flow Baffled Flocculator

2. Mechanical Type of Flocculator

Paddle flocculators are widely used in practice. The design criteria are depth of

tank = 3 to 4.5 m; detention time, t = 10 to 40 min. normally 30 min; velocity of

flow = 0.2 – 0.8 m/s normally 0.4 m/s; total area of paddles = 10 to 25% of the

cross-sectional area of the tank; range of

peripheral velocity of blades = 0.2 – 0.6 m/s; 0.3-

0.4 m/s is recommended; range of velocity

gradient; G = 10 to 75 s-1 range of dimensionless

factor Gt= 104 – 105 and power consumption;

10.0 to 36.0 kw/mld, outlet velocity to settling

tank where water has to flow through pope or

channel = 0.15 to 0.25 m/s to prevent settling or

breaking of floes. For paddle flocculator, the

velocity gradient is given by

In which CD = Coefficient of drag (0.8 to 1.9),


Preparation of DPRs

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Ap=area of paddle (m2),

Volume of water in the Flocculator (m3)

Vp= Velocity of the tip of paddle (m/s),

VW= Velocity of the water adjacent to the tip of paddle (m/s)

The optimum value of G can be calculated

In which

G= Optimum velocity Gradient, s-1

t = time of flocculation, min; and

c= alum concentration (mg/l)

3.5.3 Clariflocculators Clariflocculators are widely used in the country in water and wastewater

treatment. The coagulation and sedimentation processes are effectively

incorporated in a single unit in the clariflocculator. All these units consist of 2 to 4

floculating paddles placed equidistantly.

Settling zone

The rectangular tanks have lengths commonly upto 30 m but larger lengths upto

100 m have also been adopted. The length to width ration of rectangular tanks

should preferably be from about 3:1 to 5:1. the narrower the tank, the less

chance there is for setting up of cross currents and eddies due to wind action,

temperature changes and other factors involved. In very large size tanks where

the depth is necessarily great, it may be advisable to provide longitudinal baffles

to confine the flow to definite straight channels.

The diameter of the circular tank is governed by the structural requirement of the

trusses that carry the scraping mechanism. Circular tanks up to 60 m in diameter

are in use but are generally up to 30 m to reduce wind effects. Square tanks are

generally smaller usually with side upto 20 m. Square tanks with hopper bottoms

having vertical flow have sides generally less than 10 m to avoid large depths.

The decomposition of the sludge adversely affects the settling process. Depths

commonly used in practice very from 2.5 to 5 m with 3.0 being a preferred value.

Bottom slopes may range from 1% in rectangular tanks to about 8% in circular

tanks. The slopes of sludge hoppers range from 1.2:1 to 2:1 (Vertical:

horizontal).

3.5.4 Sedimentaion There are two types of Sedimentation tanks.

1. Horizontal Flow Tanks and

2. Vertical Flow Tanks


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1. Horizontal Flow Tanks

in the design of a horizontal flow tank, the aim is to achieve as nearly as possible

the ideal conditions of equal velocity at all points laying on each vertical line in

the settling zone. The direction of flow in the tanks is substantially horizontal.

Among the representative designs of the horizontal flow settling tanks, the

following may be mentioned:

2. Vertical Flow Tanks

Vertical flow tanks normally combine sedimentation with flocculation. These tanks

are square or circular in plan and may have hopper bottoms. The influent enters

at the bottom.

3.5.5 Filtration The purpose of filtration is the removal of particulate impurities and flocs from the

water being treated. In this regard, the filtration process is the final step in the

solids removal process which usually includes the pre-treatment processes of

coagulation, flocculation and sedimentation. The degree of treatment applied

prior to filtration depends on the quality of water. Typical surface loading rates

and detention periods are presented in table3.1

Table3.1: Common Surface Loading and Detention Periods

Surface Loading m3/m2/d*

Detention period, hr*

Tank Type

Range Typical Value for Design

Range Typical value for design

Particles normally removed

Plain Sedimentation Upto

6000 15-30

0.01 -

15 3-4

Sand, silt&

clay

Horizontal flow, circular 25-75 30-40 2-8 2-2.5 Alum & iron

floc

Vertical flow (upflow)

clarifiers - 40-50 - 1-1.5 Flocculent

* at average design flow

Source: CPHEEO Manual 1999

3.5.6 Slow Sand Filter Slow Sand filtration was the first type of porous media filtration used in water

treatment. This process is known for its simplicity and efficiency.

During the initial operational period of slow sand filters, the separation of organic

matter and other solids generates a layer of biological matter on the surface of

the filter media.


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Design Consideration Design period – 10 years

Plant capacity

It would be convenient to convert the daily required volume to a design flow Q,

the quantity of water to be treated per hour rather than per day. Thus for a given

daily out put the size of plant depends on duration of filter operations.

Filtration Rate and No. of filters

It is desirable to design filter for a normal filtration head of 0.1 m/hr. Min. of two

filter units should be provided. This will restrict the over load rate to 0.2 m/hr

when one unit is taken out for cleaning and would ensure uninterrupted

productions. For a given area, the optimum number and size of filters which will

be only 10% more expensive than the minimum 2 bed unit are given in

TABLE.3.2

Table 3.2: Recommended Nos. of Slow Sand Filters for given Plan Areas.

Area in sq. m. No. of Beds. Upto 20 2

20 to 249 3

250 to 649 4

650 to 1200 5

1201 to 2000 6


Depth of Filter Box

The elements that determine the depth of the Filter Box and their suggested

depths are free board ( 0.2m ), supernatant water reservoir (1.0m), filter sand

(1.0m), supporting gravel (0.3m), and under drainage system (0.2m) with a total

depth of 2.7m. The use of proper depths for these elements can reduce cost of

filter box considerably without adversely affecting efficiency.

Table 3.3: Summary of Guidelines for Design of Slow Sand Filters

Description Recommended Design Value

Description Recommended

Design Value

Design Period 10years Depth of

Supernatant water 1.0m

Filtration rate Free board 0.2m

Normal operation 0.1m/hr Depth of filter sand

Initial 1.0

Max. overload rate 0.2m/hr Final (minimum) 0.4m

Number of filter

beds minimum 2

Size of sand Effective

size 0.2 to 0.3

Area up to 20M2 Uniformity coefficient 5


Preparation of DPRs

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Description Recommended Design Value

Description Recommended

Design Value

(U,C)

Are up to 20 249

smt 3 Gravel (3-4laers)depth 0.3 m

Area up to 250-649

smt 4

Under drain(Made of

bricks or perforated

pipes

0.2 m

Area up to 650-

1200 smt 5 Depth of filter box 2.7m

Area up to 1201-

2000 smt 6

Effluent weir level above

sand bed 20-30ml


Filter Sand and Gravel: Undue care in the selection and grading of sand for

slow sand filters is neither desirable nor necessary. Use of builder grade or locally

available sand can keep the cost low. Similarly, rounded gravel, which is often

quite expensive and difficult to obtain, can be replaced by hard, broken stones to

reduce cost. Guidelines for design of Slow Sand Filter are in Table 3.3.

3.5.7 Rapid Sand Filtration Plant

Rate of Filtration: The standard rate of filtration through a rapid sand filter is

usually 80 to 100 kpm / m2 (4-6-8 m / hr). Practice is tending towards higher

rates (up to 10 m/hr) in combination with greater care in conditioning the water

before filtration and with the use of coarser sand (effective size up to 1 mm). A

careful arrangement would be to design the filter on the basis of average

consumption at a normal rate of 4.8 m / hr but with the inlet and outlet control

arrangements designed to permit a 100% overload for emergent occasion.


Preparation of DPRs

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Capacity of Filter Units: A maximum area of 100 m2 for a single unit is

recommended for plants of greater than 100 mld consisting of two halves each of

50 m2 area. Also for flexible of operation a minimum of 4 units should be

provided which could be reduced to 2 for smaller plants.

Dimension of Filter Units: Layout of the plant, economy and convenience

determine the relationship between the length and the breadth of the units.

Where filters are located on both sides of a pipe gallery, the ratio of length to

width of a filter-box has been found to lie, in number of installations, between

1.11 and 1.66 average about 1.25 to 1.33. A minimum overall depth of 2.6m

including a free board of 0.5 m is adopted.

Filter Sand: Filter sand is defined in terms of effective size and uniformity

coefficient. Effective size is the sieve size in millimetres that permits 10% by

weight to pass. Uniformity in size is specified by the uniformity coefficient which

is the ratio between the sieve that will pass 60% by weight and the effective size.

Shape, size and quality of filter stand shall satisfy the following norms:

• Sand shall be of hand and resistant quartz or quartzite and free of clay, fine

particles, soft grains and dirt of every description.

• Effective size shall be 0.45 to 0.70 mm

• Uniformity coefficient shall not be more than 1.7 nor less than 1.3

• Ignition loss should not exceed 0.7 % by weight.

• Soluble fraction in hydrochloric acid shall not exceed 5.0% by weight

• Silica content should be not less than 90%

• Specific gravity shall be in the range between 2.55 to 2.65

Wearing loss shall not exceed 3%

Depth of Sand: Usually the sand layer has a depth of 0.6 to 0.75m, but for

higher rate filtration when the coarse medium is used, deeper sand beds are

suggested. The standing depth of water over filter varies between 1-2 m. The

free board above the water level should be at least 0.5 m so that when air

binding problems are encountered, it will facilitate the additional levels of 0.15 to

0.30 m of water being provided to overcome the trouble.


Preparation of DPRs

CEPT, Ahmedabad 26


Box: Sample Calculation of Rapid Sand Filter

Step-1 Suppose Water demand is 9 mld of a city

Step-2 According to Morrel and Wallance formula, the number of units of a filter plant, N = 1.22 x Sqrt of Q =1.22x 3 = 3.66 say 3 nos.

Step-3 Maximum water demand =demand x peak factor=1.8x9000000 per day Hence per hour demand =(1.8x9000000) / 24 =675000 liter per hour

Step-4 Now let us assume rate of filtration is 4000 liter / hr/ sq.m Hence Total area required for filter beds = water demand/Rate of filtration = 67500/4000 sq.m = 168 .75 sq.m

Step-5 Area of each unit = 168.75 / 3 =56.25 Assuming L=1.5 B; Hence 1.5BxB =56.25 B2 = 56.25Hence B=6.12 say 6.15 m. Hence L=1.5 x6.15=9.20 m. H f 9 ld t it d d 3 id d filt h ld b d i d

Preparation of Filter Sand: From a sieve analysis of the stock sand, the

coarse and fine portion of stock sand that must be removed in order to meet the

size specifications, can be computed in terms of p1, the percentage of suitable

stock sand that is smaller than desired effective size d, which is also equal to

10% b of the usable sand P2, the % of the stock sand that is smaller than the

desired 60 percentile size d2. The percentage of suitable stock sand p3 is

than=2(p2-p1)because the sand lying between the d1 and d2 sizes will constitute

half the specified sand.

To meet the specified composition, this sand can contain 0.1p3, i of a sand below

d1,size. Hence the percentage of p4, below which the stock sand is too fine to

use, is

P4=p1-0.1p3=p1-0.2(p2-p1) =1.2p1-0.2p2

Likewise, the %age p5 above which the stock sand is too coarse for use is

p5=p2+0.4% of usable sand

=p2+0.4x2(p2-p1) = p2 + 0.8(p2-p1) = 1.8 p2 -0.8 p1

Size of gravel and depth of gravel layer shall be determined in accordance with

the following rules:

For strainer or wheeler type under-drain system, gravel shall be 2 mm minimum

size, 50 mm maximum size and 0.3 to 0.5 m deep and


Preparation of DPRs

CEPT, Ahmedabad 27


For perforated pipe under-drain system, gravel shall be 2 mm minimum size and

0.5 m in depth

Wash water Gutter The troughs are designed as free falling weirs or spillways, for free falling

rectangular troughs with level invert, the discharge capacity Q in M3 / s may be

computed from the formula

Q = 1.376 x b x h 3/2

Where b is the width of the trough in m and h is the water depth in m.

The pre-treatment units which form essential parts of a Rapid sand filtration unit

include

(a) Coagulation and flocculation with rapid mixing facilities

(b) Sedimentation units.

Following different figures 3.2 and 3.3 shows different type of units being

provided in various cities:


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CEPT, Ahmedabad 28


(i) In-Line Filtration

Figure3.2: Conventional Filtration

Figure 3.3 Direct Filtration

3.5.8 Disinfection


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Objective: The primary objectives of the chlorination process are disinfection,

taste and odour control in the system, preventing the growth of algae and other

micro organisms that might interfere with coagulation and flocculation, keeping

filter media free of slime growths and mud balls and preventing possible built up

of anaerobic bacteria in the filter media, destroying hydrogen sulphide and

controlling sulphurous taste and odour in the finished water, removing iron and

manganese, bleaching of organic colour.

It can also be used for flushing pipeline before it is brought into operation after

carrying out repairs etc. However in such case chlorinator is adjusted to apply

chlorine or hypochlorite solution at the rate of 50 ppm. heavily chlorinated water

should be allowed to stand in the pipeline for at least 30 min. and preferably for

12 hours before being replaced with potable water.

Chlorine reacts with water to form hypochlorous acid (HOCl) and Hydrochloric

acid (HCl). This hydrolysis reaction is reversible. The hypochlorous acid

dissociates into hydrogen ions (H+) and hypochlorite ions (OCl—), free available

chlorine is hypochlorous acid and hypochlorite ions.

• This free available chlorine can react with compounds such as ammonia,

proteins, amino acids and phenol which may be present in the water, forming

chloramines and chloro-derivatives which constitute the combined chlorine.

• Chlorination in presence of humic acid and fulvic acid forms Tri-halomethane

(THM) which is a heath hazard.

• The combined available chlorine has less disinfecting properties as compared

to free available chlorine.

• For more details please refer to Manual on “Water Supply and Treatment”,

(1999 Edition).


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3.5.9 Water Treatment Plant Information, Operation, Maintenance, Records etc. of Water Treatment Plant are

describes in the following:

Plant Information

Source:-

Surface - i. River ii. Reservoir iii. Dam iv. Lake v. Canal.

Ground - i. Well ii. Tubewell iii. Infiltration well/gallery

Intake:-

i. Location. ii. Pollution Source iii. Gates and Valves iv. Structural details.

Treatment Process

1. Screens

2. Storage tanks/Pre-settling tanks

3. Pre-disinfection/Pre-chlorination

4. Aeration

5. Coagulation and Flocculation

• Mixing tank or Mixing channel,

• Chemicals: lime, alum, or others

Process may be of Conventional or tapered flocculation with independent tank or

in the form of a clarifier.

6. Sedimentation

Tanks may be (circular or rectangular).If circular; it may have either

clariflocculators with or without Scrapers.

7. Filters


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Filtration process may be by Slow Rapid sand filter or slow sand filter but, in both

the cases they will have filter box and filter media

8. Clear Water Tanks

Number and size clear water tank may be decided Capacity.

3.6 Quality Standards The Environmental Hygiene Committee (1949) recommended that the objective

of a public water supply should be to supply water "that is absolutely free from

risks of transmitting diseases, is pleasing to the senses and is suitable for culinary

and laundering purposes" and added that " freedom from risks is comparatively

more important than physical appearance or hardness" and that safety is an

obligatory requirement and physical and chemical qualities are optional within a

range. The physical and chemical quality of drinking water should be in

accordance with the recommended guidelines mentioned in table. Ceased with

the introduction of the Manual on Water Supply and Treatment, third edition-

revised 1999, Ministry of Urban Development, Government of India, wherein the

following Water Quality norms have recommended and presented in table 3.3

Table 3.3 Recommended Guidelines for Physical and Chemical Parameters

Sr. No.

Characteristic Acceptable Cause for Rejection

1 Turbidity (NTU) 1 10

2 Colour ()Units on Platinum Cobalt scale) 5 25

3 Taste and Odour Unobjectionable Objectionable

4 pH 7.0 to 8.5 <6.5 or> 9.2

5 Total dissolved solids (mg/l) 500 2000

6 Total Hardness (as CaCO3) (mg/l) 200 600

7 Chlorides (as Cl) (mg/l) 200 1000

8 Sulphates (as SO4) (mg/l) 200 400

9 Fluoride (as F) (mg/l) 1.0 1.5

10 Nitrates (as NO3) (mg/l) 45 45

11 Calcium (as Ca) (mg/l) 75 200

12 Magnesium (as Mg) (mg/l) < 30 150

If there are 250 mg/l of sulphates, Mg content can be increased to maximum of mg/l with

the reduction of sulphates at the rate of unit per every Units of sulphates

13 Iron (as Fe) (mg/l) 0.1 1.0

14 Manganese (as Mn) (mg/l) 0.05 0.5

15 Copper (as Cu) (mg/l) 0.05 1.5

16 Aluminium (as Al) (mg/l) 0.03 0.2


Preparation of DPRs

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Sr. No.

Characteristic Acceptable Cause for Rejection

17 Alkalinity (mg/l) 200 600

18 Residual Chlorine (mg/l) 0.2 >1.0

19 Zinc (as Zn) (mg/l) 5.0 15.0

20 Phenolic compound (as Phenol) (mg/l) 0.001 0.002

21 Anionic detergent (mg/l) (as MBAS) 0.2 1.0

22 Mineral Oil (mg/l) 0.01 0.03

TOXIC MATERIALS

23 Arsenic (as As) (mg/l) 0.01 0.05

24 Cadmium (as Cd) (mg/l) 0.01 0.01

25 Chromium (as hexavalent Cr) (mg/l) 0.05 0.05

26 Cyanides (as CN) (mg/l) 0.05 0.05

27 Lead (as Pb) (mg/l) 0.05 0.05

28 Selenium (as Se) (mg/l) 0.01 0.01

29 Mercury (total as Hg) (mg/l) 0.001 0.001

30 Polynuclear aromatic hydrocarbons (PAH)

(µg/l) 0.2 0.2

31 Pesticides (total, mg/l) Absent

Refer to WHO

guidelines for

drinking water

quality Vol I-

1993

RADIO ACTIVITY

32 Gross Alpha activity (Bq/l) 0.1 0.1

33 Gross beta activity (Bq/l) 1.0 1.0



Preparation of DPRs

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Recommended guidelines for physical and chemical parameters

The figures indicated under the column ‘Acceptable’ are the limits upto which

water is generally acceptable to the consumers. Figures in excess of those

mentioned under ‘acceptable’ render the water not acceptable but still may be

tolerated in the absence of an alternative and better source but upto the limits

indicated under column “Cause for Rejection” above which the sources will have

to be rejected.

It is possible that some mine and spring waters may exceed these radio activity

limits and in such cases it is necessary to analyze the individual radio-nuclides in

order to assess the acceptability or otherwise for public consumption.

Bacteriological Quality of Drinking Water

Organisms Guideline value All water intended for drinking

E coli or thermo-tolerant coliform bacteria

b,c

Treated water entering the distribution

system

E. coli or thermo-tolerant coliform bacteria

b

Total coliform bacteria

Treated water entering the distribution

system

E. coli or thermo-tolerant coliform bacteria

b

Total coliform bacteria

Must not be detectable in any 100-ml

sample


sample


sample


sample


sample. In case of large supplies, where

sufficient samples are examined, must not

be present in 95 % of samples taken

through out any 12 method period.

Source: WHO guidelines for Dinking Water quality Vol. 1 - 1993


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Table 3.4 Recommended Treatments for Different Water Sources to Produce Water with negligible Virus Riska

type of sources Recommended treatment

ground water protected, deep well; essentially free of faecal contamination unprotected, shallow wells; feacally contaminated

surface water protected, impounded upland water; essentially free of faecal contamination unprotected impounded water or upland river; faecal contamination unprotected lowland rivers; faecal contamination unprotected lowland rivers; heavy faecal contamination unprotected watershed; gross faecal contamination

disinfection filtration and disinfection disinfection filtration and disinfection pre-disinfection or storage, filtration, disinfection pre-disinfection or storage, filtration, additional treatment and disinfection not recommended for drinking water

Source: CPHEEO manual 1999

• For all sources, the median value of turbidity before terminal disinfection must

not exceed 1 nephelometric turbidity unit (NTU).

• Terminal disinfection must produce a residual of free chlorine of > 0.5 mg/litre

after atleast 30 minutes of contact in water at pH < 8.0, or must be shown to

be an equivalent disinfection process in terms of the degree of enterovirus

inactivation (>99.99 %).

• Filtration must be either slow and siltration or rapid filtration (sand, dual, or

mixed media) proceeded by adequate congulation-flocculation (with

sedimentation or floatation). Diatomaceous earth filtration or filtration process

demonstrated to achieve > 99 % enterovirus reduction.

• Disinfection should be used if monitoring has shown the presence of E.coli or

thermo-tolerant coliform bacteria. Source: W.H.O. guidelines for Drinking Water Quality - 1993

Note: The figures indicated under the column 'Acceptable' are the limits up to which water is generally

acceptable to the consumers. Figures in excess of those mentioned under 'Acceptable' render the

water not acceptable, but still may be tolerated in the absence of an alternative and better source but

up to the limits indicated under column "Cause for Rejection" above which the sources will have to be

rejected.


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3.7 Distribution System An accurate and detailed water supply distribution system can be designed after

the following information is available.

• Detailed survey of levels of the area/zones/sectors.

• Zones and their individual water requirements.

• Detailed internal layout of some sectors especially reserved sectors (as per

the layout plan).

• Internal road networks inside the sectors.

Table 3.5: Peak factors for Contributory Population

Contributory population Peak Factor Upto 50,000 3.00

50,000 to 2,00,000 2.50

Above 2,00,000 2.00


3.7.1 Design of Pressure Pipelines Generally a pipe is a closed conduit which is used for carrying fluids under

pressure. Pipes are commonly circular in section. As the pipes carry fluids under

pressure, the pipes always run full. The fluid flowing in a pipe is always subjected

to resistance due to shear forces between the fluid particles and the boundary

walls of the pipe and between the fluid particles themselves resulting from the

viscosity of the fluid.

As stated earlier the frictional resistance offered to the flow depends on the type

of flow. As such different laws are obeyed by frictional resistance in laminar and

the turbulent flows. Generally, water flowing through pipes in water distribution

systems is assumed as laminar flow. On the bases of the experimental

observation, the laws of fluid friction for laminar flow may be narrated as follows:

Laws: The frictional resistance in the laminar flow is

(i) Proportional to the velocity of flow,

(ii) Independent of the pressure,

(iii) Proportional to the area of surface in contact,

(iv) Dependent of the nature of the surface in contact,

(v) Greatly affected by the variation of the temperature of the flowing fluids.

While designing the pipe section velocity through pipe section is assumed 0.8 to

1.6 m/s .As a rule of thumb for design assume higher velocity of 1.2 to 1.4

In normal case it is assumed 1.4 m/s

With assumption of velocity diameter of the pipe section is determined by

Q= [(Л/4)d2 ] × v (where Q in m3/s)


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The pipe section and material is fixed for calculating head loss through the

section.

It is important to know the residual pressure of water flowing through the

pipelines wherein the hydraulic gradient over its entire length lays above the

crown / sofit of the pipelines. However the designed pipeline is governed by

Hazen-Williams equation.

3.7.2 Minimum Pipe Sizes Minimum pipe sizes (diameter) required and recommended by CPHEEO are 100

mm for towns having population upto 50,000 and 150 mm for those above

50,000. Pipelines having size less than 100 mm can be considered for dead ends.

3.7.3 Pipe and Material of Construction Pipe materials generally used for water supply network are cast iron(CI),

reinforced cement concrete(RCC), pre-stressed concrete, asbestos cement(AC),

rigid PVC, ductile iron(DI), fibre glass pipe, glass reinforced plastic, fibre

reinforced plastic, low density and high density polyethylene(HDPE), etc.

The manufacturing process of AC pipes is known to be carcinogenic, and thus

many water supply boards have stopped using AC pipes. RCC pipes are prone to

O & M problems and are difficult to maintain. CI pipes are prone to corrosion,

though they are advantageous over cost considerations as well as in terms of

O&M. The HDPE pipe is the cheapest material, but their overall performance in

many cities is far from satisfactory. The cost of DI pipe is very high, however,

these pipes could be considered under adverse soil conditions. Considering the

problems that each type of pipe material has, use of PVC pipes is the most

suitable option.

Equation Hf = (f ×L× v2)/(2×g×D) is known as Darcy – Weishbach equation

which can be used for computing the head loss due to friction in pipes.

Where v is velocity of water flowing through the pipe.

,f frictional factor

,L length of the pipes

,g is acceleration due to gravity

,D Diameter of the pipe.

But, f is independent of the pipe material and therefore not in use.

The Standard Hazen–Williams formula commonly in use for Head loss calculation

through pipe section

Q=3.1×10-4 × c × D2.63 ×S0.54

Where Q is in KLd, C is H-W coefficient, D is in mm,

And S is hydraulic loss in mt / mt


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The values of the Hazen – Williams’s coefficient ‛C’ for new conduits and the

values as recommended in the Manual on Water Supply and Treatment third

edition-revised 1999,Ministry of Urban Development, Government of India to be

adopted for design purposes are recommended as under in table 3.6.

Table 3.6: Recommended C Values

Pipe Material Recommended C for New@ Pipes

Unlined Metallic Pipes

Cast Iron, Ductile Iron 130

Mild Steel 140

Galvanized Iron above 50 mm dia. # 120

Galvanized Iron 50 mm dia and below used for house service

connections. # 120

Centrifugally Lined Metallic Pipes

Cast Iron, Ductile Iron and Mild Steel Pipes Lined with cement mortar or

Epoxy. Up to 1200 mm dia. 140

Above 1200 mm dia. 145

Projection Method Cement Mortar

lined Metallic Pipes Cast Iron , Ductile Iron and Mild Steel Pipes 130*

Non Metallic Pipes

RCC Spun Concrete , Prestressed Concrete

Up to 1200 mm dia. 140

Above 1200 mm dia. 145

Asbestos Cement 150

PVC , GRP and other Plastic pipes 150


@ The C value for new pipes included is for determining the acceptability of

surface finish of new pipelines

# The quality of galvanizing should be in accordance with the relevant standards

to ensure resistance to corrosion throughout its design life.

* For pipes of diameter 500 mm and above. The range of C values may be from

90 to 125 for pipes having diameters less than 500 mm.

And Check the velocity of flow through pipe by equation V=4.567×10-

3×C×D0.63× S0.54

Where D is in mm and v is in m/s

3.7.4 Modified Hazen – Williams Formula Hfm = {[ L ( Q/Cr)1.81 ]/994.62 } × D 4.81

Where q is in mld, D is in mm ,Cr =1

Note: -

1. Standard Hazen–William formula generally used for hydraulic


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designs of pressure pipelines is having certain limitations.

The results obtained by its use suffer from considerable inaccuracies. Thus its use

resulted generally in over- designing of pipelines.

In spite of the fact that the modified H-W formula is more rational, it is not being

widely used at present. One of the reasons may be non–availability of design

aids for the same.

Calculate actual Hydraulic loss as actual length of pipe section H

Loss = S × L /1000 mt.

Where, S = slope, L = length

Calculate cumulative hydraulic loss adding 10% extra loss for unaccounted losses

flowing direction of water through pipe.

Now considering the reduced level of source of supply and tail end of the pipe

section calculate the Residual Pressure.

3.7.5 Residual Pressure Piped water supplies should be designed such as to distribute water to consumers

on continuous 24 hours basis at adequate pressure at all points. Intermittent

supplies are neither desirable from the public health point of view nor economical.

For towns where one-storied buildings are common and for supply to the ground

level storage tanks in multi-storied buildings, the minimum residual pressure at

ferrule point should be 7m for direct supply. Where two-storied buildings are

common, it may be 12m and where three-storeyed buildings are prevalent 17 m

or as stipulated-by local byelaws. The pressure required for fire fighting ring

would have to be boosted by the fire engines.

The distribution system would be designed for the following minimum residual

pressures at end points as given in the table 3.7. Minimum Residual pressures are

governed by Building Bye-laws of the city.

Table 3.7: Minimum Residual Pressures Requirement

Type of Building Minimum Residual Pressure Ground Level Structure 7 m

G+1 12 m

G+2 17 m



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Box-1 :

Sample-

Calculation

for Town: -

Vijaynagar

Population :-

Census Year

Population Decadal Growth Rate

Increasing/decreasing growth rate

1981 4005 -

1991 4871 21.62

2001 5676 16.52 -5.1

2011 6324 Assumed

11.42

Water

discharge

demanded

in2011 for

one day is

Q= 6324

×135 × 3

=2561220

lpd =2.56

mld

Diameter of

main pipe

supplying

water from

ESR t

3.8 Case Study of Rajkot City Engineering Design for ESR & GSR in Ward No.6 of Rajkot City: Present

population of the proposed site of ESR and GSR is around 1.25 lacs and same will

be about 1.60 lacs in the year 2015. Considering the supply 30 gallons per capita

per day, the total present requirement works out to 37.50 lakhs gallons per day

and that of for the year 2015 works out to 48 lakhs GPD. Ideally 24 hours storage

of future requirement of 48 lakhs gallons per day is required to be provided but

because of the limited space, it is proposed to provide storage of 14 hours

capacity of ultimate stage requirement. With this the storage capacity works out


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to 28 lakhs gallons i.e. 12.75 M.L., provide ground storage 10 M.L. and elevated

stage - 3 M.L.

Civil Design Component: (1) Design of inlet pipe line (from off take point in Aji-Mavdi main of 850 mm

dia.)

The present population of sub head work 1.25 lacs

The population for the year 2015 1.60 lacs

Considering rate of W.S. 30 GPCD

The requirement of water works are as under

For 2005- 1.25 x 30 = 37.5 lacs gallon = 17.02 ML

For 2015 1.60 x 30 = 48 lacs gallon = 21.79 ML

Storage capacity 13 M.L. to be filled up in 14 hours.

∴ In let pipe capacity...... 13

14

= 0.9285 ML/hr.

= 0.2579 m3/ sec

Assume velocity 1.2 mt/sec.

The size of inlet main work out to 0.258 = A x 1.2

∴D= 523 mm ø

Say 500 mm ø M.S. or 450 mm ø D.I.

Size of ESR-GSR: Size of GSR .

10 ml capacity provide two compartment

Capacity of one compartment - 5 ml = 5000 m3

Provide water depth 4.5 mt.

Therefore area 5000m3 = 1111.11 sq.mt.

4.5

Provide rectangular size

L X B = 1111.11 sq.mt.

Assume L = 1.25 B

Therefore, 1.25 B x B = 1111.11

Therefore, B2 = 1111.11 = 888.88

1.25

Therefore, B = 29.81 mt. Say 30 mt.

therefore, L = 37.50

Provide GSR size 37.5 x 30 x 4.5 = 5062.5 m3

Size of ESR .

Capacity of ESR is proposed of 3 ML.

Therefore, provide ESR with shaft dia. - 15.0 mt. and water depth in container 6

mt

Height of ESR – 25 mts.


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(3) Design of pumping machinery

Provide electrically driven C.F. sets

Total period of supply - 6 hrs.

Quantity to be supplied - 17.02 ML present = 2836.66 m3/hr

21.79 ML Future = 3631.66 m3/hr

Provide 3 set working for present demand

Therefore, size 2836.66 = 945.55 Say: 946 m3/hr

3

For ultimate demand 4 sets will be working.

Therefore, 946 x 4 = 3784 m3/hr > 3632 m3/hr

Therefore, provide six sets each having capacity ,946 m3/hr against head of 35

mt.

Therefore K.W. = 946 x 35 x 1.15 = 129.61

367.2 x 0.8 Say 130 KW

Therefore, Total K.W. .. 130 x 6 = 780 KW

Actual load 20 KW

800 KW

For present stage 100% standby (3+3)

For ultimate stage 50% standby (4+2)

(4) Design of pipe size

Rising main from P.H. to ESR

Total quantity 946 x 4 = 3784 m3/hr 1.051 m3/Sec.

Assume velocity 2 mt/sec.

∴ 1.051 = A x 2

∴ d = 818 mm dia.

Say 800 mm dia.

∴ for ESR

Size of inlet - 800 mm dia

Size of outlet - 850 mm dia

Size of over flow - 850 mm dia

Size of washout - 200 mm dia

Refer Guidelines and Specification for Civil, Mechanical and Electrical

works which are provided in CD


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4.0 Design Criteria of Sewerage Projects

4.1 Objective The objective of a public waste water collection and disposal system is to ensure

that sewage or excreta and sullage discharged from communities is properly

collected, transported, treated to the required degree and finally disposed off

without causing any health or environmental problems.

Waste water disposal systems can be either the on-site type or the kind where

water –borne wastes are disposed off-site into a water body or on land. To keep

overall costs down, most urban systems today are planned as an optimum mix of

the two types depending on various factors.

4.2 Main Considerations In designing waste water collection, treatment, and disposal systems, planning

generally begins from the final disposal point going backwards to give an

integrated and optimum design to suit the topography and the available hydraulic

head, supplemented by pumping if essential. Once the disposal points are

tentatively selected, further design is guided by the following design

considerations:

• Engineering

• Environmental

• Process

• Cost

•

4.2.1 Engineering Considerations • Design period, stage wise population to be

served and expected sewage flow and

fluctuations.

• Topography of the general area to be

served, its slope and terrain. Tentative sites

available for treatment plant, pumping

stations and disposal works.

• Available hydraulic head in the system upto

high flood level in case of disposal to a

nearby river or high tide level in case of

coastal discharge or then level of the irrigation area to be commanded in case

of land disposal.

• Ground water depth and its seasonal variation affecting construction, sewer

infiltration, and structural design (uplift).


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• Soil bearing capacity and type of strata expected to be met at the time of

construction.

• Onsite disposal facilities, including the possibilities of segregating the sullage

water and sewage and reuse or recycle sullage water within the households.

4.2.2 Environmental Considerations • Surface water hydrology and quality.

• Ground water quality.

• Coastal water quality

• Odour and Mosquito nuisance

• Public Health

• Landscaping

4.2.3 Process Considerations • Waste water flow and Characteristics

• Degree of treatment required

• Performance characteristics

• Other process requirements

• Cost considerations

4.3 Design Period Sewerage projects may be designed normally to meet the requirements over a

thirty year period after their completion. The period between design and

completion should also be taken into account which should be between three to

six years depending on the type and size of the project.

The length of time up to which the capacity of a sewer will be adequate is

referred to as the design period. Sewerage projects may be designed normally to

meet the requirements over a thirty year period after their completion. The period

between design and completion should also be taken into account which should

be between three to six years depending on the type and size of the project. The

project components may be designed to meet the periods mentioned in table 4.1

below:

Table 4.1: Design Periods for components of sewerage system and sewage treatment

Sr.No

Component

Recommended Design Period

(in Years)

Clarification

1 Collection System

i.e. Sewer Network 30

The system should be designed for the

prospective population of 30 years as its


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Sr.No

Component

Recommended Design Period

(in Years)

Clarification

replacement is not possible during its use

2 Pumping Stations

(Civil Works) 30

Duplicating machinery within the pumping

station would be easier/cost of civil works

will be economical for full design period.

3 Pumping Machinery 15 Life of pumping machinery is Generally 15

years

4 Sewage Treatment

Plant 30

The construction may be in a Phased

manner as initially the flows may not

reach the designed levels and it will be

uneconomical to build the full capacity

plant initially.

5 Effluent disposal and

Utilization 30

Provision of design capacities in the

initial stages itself is economical.

Source: CPHEEO, 1991

4.4 Population Forecast As per module 2.2: Demand Assessment

4.5 Sewage Generation As per the CPHEEO norms, sewage generated will be considered as 80% of the

water reaching the consumer end. Such assumption will lead to more realistic

sewage flow considerations and economical design of sewerage system. The

sewage flows considered for design of the sewerage system will comprise of

sewage emanating from domestic, commercial and industrial premises. An

infiltration allowance of 5 % should be considered.

4.5.1 Sewage flows Sewage flows for the design of sewers will include peak dry weather flows of

domestic sewage from residential, commercial and institutional areas. Generally

80% of the water supply may be expected to reach the sewers unless there is

data available to the contrary. However the sewers should be designed for a

minimum waste water flow of 100 litres per capita per day.

4.5.2 Peak factors The flow in sewers varies considerably from hour to hour and also seasonally but

for the purposes of hydraulic design it is the estimated peak flow that is adopted.

The peak factor or the ratio of maximum to average flows depends upon

contributory population and the following values (refer table 4.2) are

recommended.


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Table 4.2: Peak factors for Contributory Population

Contributory Population Peak factor upto 20,000 3.00

20,000 to 50,000 2.50

50,000 to 7,50,000 2.25

above 7,50,000 2.00


4.5.3 Self Cleansing Velocities Velocity of flow of waste water is assumed 0.6 m/s for deciding the size of sewer

line. The flow velocity should not be less than 0.4 m/s and not greater than 2.44

m/s. Discharge of waste water is computed by

Qf = future population × per capita discharge × Peak factor

And Qt = 1.25 × Qf

With assumption of velocity diameter of the pipe section is determined by

Q= [(Л/4) d2 ] × v (where Q in m3/s)

4.5.4 Minimum size of sewers Minimum Size (diameter) of sewers in urban areas should be 150 mm and 100

mm in hilly areas.

The Manning formula given below is commonly used for such design of sewer line.

V = (1 / N ) × R 2/3 × S ½ Where R = Hydraulic radius

For circular conduit Hydraulic radius R = D/4

Hence For circular conduit ,

V = (1/N ) × 0.003968 × D2/3 × S1/2

And Qt = (0.2693/106 ) × (1/N) × D 8/3 × S1/2

Where Qt = quantity of flow in mld

D = dia . of the pipe in mm

N = Manning`s coefficient of roughness

S = slope of hydraulic gradient (generally slope of pipelines)

Values of 1 in L (gradient) are obtained which are inverse values of slope i.e. 1/S

The values of Manning`s Coefficient (Coefficient of Roughness) recommended for

different pipe materials are given below.


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Type of Pipe Material Condition N

Sault glazed stoneware pipes (a) good 0.012

(b)Fair 0.015

Cement Concrete Pipes. (a)good 0.013

(with collar joint). (b)Fair 0.015

Spun concrete pipes (RCC & PSC) with

Socket spigot joints (Design Value) 0.011

Steel

(a) Welded 0.013

(b)Rivetted 0.017

(c) Slightly tuberculated 0.020

(d) With spun cement mortar lining 0.011

Caste Iron

(a) Unlined 0.013

(b) With spun cement mortar lining 0.011

Asbestos cement 0.011

Plastic (smooth) 0.011

As the pipes used for sewers and drains are mostly stoneware , cement concrete ,

RCC and PSC , most of the design work is covered in using the value of N = 0.015

, 0.013 and 0.011. however for sewage pumping main CI and MS/Steel pipe could

be used.

Getting size and gradient is not final but, it should be checked for velocity of flow

by expression

Vt = (1/N) × 0.003968 × D2/3 × S1/2

Where Vt is velocity of flow of discharge Qt

Now it should be checked for minimum velocity v when ratio is

Qp/Qt = v/Vt and Qf/Qt = v/Vt

4.6 Flow Characteristics From consideration of ventilation in waste water flow, sewers should not be

designed to run full. All sewers are to be designed to flow 0.8 full at ultimate peak

flow. There are occasions when the characteristics such as velocity, discharge,

depth of flow etc. are required to be computed when the pipe lines laid at a

certain grade are flowing partly full. The Manning’s formula is, of course, the

basis, which enables determination of the full-flow characteristics. Then from the

geometrical properties of circular sections, the velocity, discharge etc. can be

calculated for partial flow conditions.


Preparation of DPRs

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The partial flow elements viz. area, velocity, discharge etc. are expressed as

ratios of the corresponding full flow values. These ratios are tabulated in the

following table 4.3

Table 4.3: Hydraulic Check

d / D v / V q / Q 1.0 1.000 1.000

0.9 1.124 1.066

0.8 1.140 0.968

0.7 1.120 0.838

0.6 1.072 0.671

0.5 1.000 0.500

0.4 0.902 0.337

0.3 0.776 0.196

0.2 0.615 0.088

0.1 0.401 0.021

D = Full Depth of flow

(internal diameter of pipe)

V = Velocity at full depth

v = Velocity at depth partial

q = Discharge partial

(at present population and future population)

Q = Discharge at full

In actual design the discharge ratio q/Q for the pipe is first known and the

velocity of flow, depth etc. at the partial flow condition are required to be

calculated. Table is given for values of ratio v/V and q/Q for different values of

d/D

4.6.1 Velocity at Minimum Flow It has been shown that for sewers running partially full, for a given flow and

slope, velocity is influenced by pipe diameter. It is therefore, recommend to

adopt slopes given below for peak flow up to 30 lps , which would ensure a

minimum velocity of 0.60 mps in early years.

4.6.2 Minimum Size of Sewer A minimum diameter of 150 mm has been considered to identify the proposed

sewer under study. Three factors are influencing for deciding the diameter of

sewer pipeline.

(1) Population of initial stage of commissioning & wastewater quantity generated.

(2) Peak flow & velocity during initial stage of commissioning for self cleansing

(3) Proposed gradient in sewer line.

4.6.3 Minimum Depth of cover To facilitate connection of house drains to branch sewers and to provide

protection to the sewers from external loads, the minimum depth of cover over

any sewer line should be 1 metre. However, the same will be considered even up

to 1.5 to 2.0 m depending on specific site conditions.


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4.6.4 Maximum Depth of Sewer Invert The maximum depth of sewer invert needs to be about 7 metres below ground

level considering the nature of soil strata, ground water table and method of

construction in the project area. Such depth limitations prevent pipes being laid in

underground water which could have lead to the problem of excessive infiltration

and added pumping costs. In rare cases, for short length consideration have been

set aside to avoid pumping stations for small lifts.

4.6.5 Ground Water Infiltration Estimation of flow in sanitary sewers may include certain flows due to infiltration

of ground water through joints. The quantity will depend on workmanship in

laying of sewers and level of the ground water table. Since sewers are designed

for peak discharges, allowance for ground water infiltration for the worst condition

in the area should be made. Suggested estimate of ground water infiltration for

sewers laid below ground water table 4.4 are as follows:

Table 4.4: Suggested estimate of ground water infiltration Minimum Maximum Litres/Ha.d 5,000 50,000

Litres/km.d 500 5,000

Lpd/manhole 250 500 Source: CPHEEO manual 1990

With improved standards of workmanship and quality and availability of various

construction aids, these values should tend to the minimum, rather than the

maximum. These values should not mean any relaxation on the water tightness

test requirements in Hydraulic testing of pipe sewers.

4.6.6 Sewer hydraulics The hydraulic design considerations are greatly influenced by the topography and

the ground water table as well as the difficulties likely to be encountered during

the construction due to soil strata With flatter slopes, the flow velocities in sewers

are low and siltation occurs. However it has to be mentioned that sewers do get

silted, even if the same are designed for higher velocities by proposing steeper

slopes due to typical situations like connections with storm water drainage, entry

of refuge, debris, etc. into the system. It must therefore be emphasised that

sewer silting can be seldom prevented. The only method for effective sewer

operation, is the periodic cleaning of sewers with suction and water jetting

machines.

Maximum depth of flow should not increase beyond 5 to 6 meters and pumping

stations may be provided to limit the depth of sewers.


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If this practical situation is accepted, the sewer velocity criteria looses the

significance with which it is all along associated. The sewer design therefore has

to be guided by the limitations of depth and practicalities such as minimising the

number of pumping stations (for obvious reasons).

4.6.7 Material of construction Pipe materials generally used for sewers are glazed stoneware, cast iron,

reinforced cement concrete; glass fibre reinforced plastic and high-density

polyethylene.

4.6.8 Joints Joints provided need to be of either collar joint or spigot & socket joint with a

rubber ring.

Box. 2 : Classes of Bedding for conduit in trench Sample Clculation : -

Vijaynagar Population (present) = 5676

Vijaynagar Population (Fututre) = 6324

Present Discharge q = 0.80 × 5676 × 135 × 3 =1839024 lpd = 1839.024 klpd =1.84 mld

Future Discharge Qf = 0.80 × 6324 ×135 × 3 =2048976 lpd = 2048.976 klpd = 2.05 mld

Design Discharge Qd = 2048976 × 100/80 = 2561220 lpd = 2561.220 klpd = 2.56 mld

Dia. Of Pipe section flowing collected wastewater to treatment plant

= sqrt of [(Qd × 4) / (3.14 × V)] =sqrt of [ (2561220 × 4) /( 1000 × 24 × 60 × 60 × 3.14 × 0.80) ]

= 0.217 mt. = 250 mm

Slope of the pipe section Qt = (0.2693/106 ) × (1/N) × D 8/3 × S1/2

S1/2 =[ (2.56 × 106 × .013 ) / (0.2693 × 2508/3)]

S = square of [ 0.04982] = 0.00248 mt /mt

Gradient = 1/s = 1/ 0.00248 = 1 in 403.22 mt

= 1 mt fall in 403 mt length

Design Velocity V = (1/N ) × 0.003968 × D2/3 × S1/2

= (1/.013) × 0.003968 × 2502/3 × 0.002481/2

= 0.603 mt/sec

q / Qd ratio = 1.84 /2.56 =0.72 ,

from above table for q/Qd v/V ratio = 1.08 ; therefore v = 1.08 × 0 .603 mt/sec

= 0.65 mt/sec which is > 0.3 mt/sec O.K

Qf /Qd = 2.05/2.56 =0.800

From above table for Qf / Qd , v/v ratio = 1.109 Therefore v = 1.109 × 0.603 mt./sec


Preparation of DPRs

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4.6.9 Type of bedding Bedding is an essential component of sewer laying and bedding of different

classes viz. A, B, C & D has given in the CPHHEO Manual on Sewerage and

Sewerage Treatment (Second Edition), December 1993 may be provided keeping

in view the depth of sewer and ground water.

The type of bedding to be provided for pipes viz. granular bedding, plain cement

concrete (M20) and cement concrete (M20) encasement will depend on the depth

at which the sewer is laid; three edge bearing strength of pipes; load due to

back-fill and superimposed vehicular traffic loads. Guidelines provided in CPHEEO

manual are followed for deciding the type of bedding.

Classes of bedding

Four classes, A, B, C, and D of bedding used most often for pipes. Class A

bedding may be either concrete cradle arch. Class B is bedding having sharp

bottom or compacted granular bedding with carefully compacted backfill. Class C

is an ordinary bedding having a shaped bottom or compacted granular bedding

but with a lightly compaction of backfill at the sides and immediately over the

pipe and hence is not recommended. Class B and C bedding with compacted

granular bedding is generally recommended. The pipe bedding material must

remain firm and not permit displacement of pipes.

The material has to be uniformly graded or well graded or well graded. Uniformly

graded material included pea gravel or one sizes of particles in stated

proportions, ranging from maximum to a minimum size, coarse sand, pea gravel

or one size materials with low percentage of over and undersize of particles in

stated proportions, ranging from a maximum toa s minimum size, coarse sand,

pea gravel, crushed screening, can be used for pipe bedding. Fine materials or

not satisfactory for stabilizing trench bottoms and are difficult to compact in a

uniform manner to provide proper pipe bedding. Well graded material is most

effective for stabilizing trench bottom and has a lesser tendency to flow than

uniformly graded materials. However, uniformly graded material is easier to place

and compact above sewer pipes.


Preparation of DPRs

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Load Factor: The load factors for the different classes of bedding are given in Table 4.5.

Table 4.5: Load Factors for Different Classes of Bedding

Class of bedding

Condition Load Factor

A a Concrete cradle-plain concrete and lightly tamped backfill 2.2

A b Concrete cradle-plain concrete with carefully tamped backfill 2.8

A c Concrete cradle – RCC Up to 3.4

A d

Arch type plain concrete

RCC with P - 0.4 %

RCC with P – 1.0 %

(‘P is the ratio of the steel to the area of concrete at the

crown’)

2.8

Up to 3.4

Up to 4.8

B Shaped bottom or compacted granular bedding with

carefully compacted backfill 1.9

C Shaped bottom or compacted granular bedding with lightly

compacted backfill 1.5

D Flat bottom trench 1.1

The granular material used must stabilize the trench bottom in addition to

providing a firm and uniform support for the pipe. Well graded crushed rock or

gravel with the maximum size not exceeding 25mm is recommended for the

purpose.

Where rock or other unyielding foundation material is encountered, bedding may

be according to one of the Classes A,B or C but with the following additional

requirements.

Class A: The hard unyielding material should be excavated down to the bottom

of the concrete cradle.

Class B or C: The hard unyielding material should be excavated below the

bottom of the pipe and pipe bell to a depth of atleast 15cm.

The width of the excavation should be atleast 1.25 tomes the outside dia of the

pipe and it should be refilled with granular material.

Total encasement of non-reinforced rigid pipe in concrete may be necessary

where the required safe supporting strength can not be obtained by other

bedding methods. The load factor for concrete encasement varies with the

thickness of concrete. The effect of M-200 concrete encasement of various

thickness on supporting strength of pipe under trench conditions is given in fig.


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Supporting strength in Embankment Conditions

The soil pressure against the side of a pipe placed in an embankment may be

significant in the vertical load of the structure.

Classes of Bedding for projecting conduits

The beddings which are generally adopted for projecting conduits laid under the

embankment conditions of installation are illustrated in figure 4.1. The

classification of the bedding is as under:

Class A: In this case the conduit is laid on a mat of concrete.

Class B: the conduit is laid on accurately shaped earth to fit the bottom of the

pipe and the sides are filled with thoroughly damped earth.

CLASS C : In this type of bedding the conduit is laid on accurately shaped earth

to fit the bottom surface of the conduit. For rock foundations the conduit is laid on

a layer of granular cushion and the sides of the conduit are filled up.

CLASS D: The conduit is laid on earth not shaped to fit the bottom of the

conduit. In case of rocky soil the conduit is laid on a shallow granular cushion.

Load Factor

The load factor for rigid pipes installed as projecting conduits under

embankments or in wide trenches is dependent on the type of bedding. The

magnitude of the active lateral soil pressure and on the area of the pipe over

which the active lateral soil pressure and on the area of the pipe over which the

active lateral pressure acts.

The load factor for projecting circular conduits may be calculated by the formula

1.431

L1 = Nzq

Where

L1 = the load factor

N = A parameter dependent on the type of bedding

z = a parameter dependent upon the area over which the lateral pressure acts

effectively and

q = the ratio of total lateral pressure to total vertical load on pipe.

Positive Projecting Conduits

The ratio ‘q’ for positive projecting conduits may be estimated by the formula

q = (mk /C0) [(H/B0) + (m/2)]

Where,

k = The Rankine’s ratio which may be taken as 0.33. The value of N for different

types of bedding for circular pipes are given in table 6.7


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Fig 4.1 Classes of Bedding for Projecting Conduits

Table4.6: Values of ‘N’ for Different Pipe Beddings

Type of Bedding Value of ‘N’

‘A’ – Reinforced concrete cradle 0.42 to 0.51

‘A’ - Plain concrete cradle 0.51 to 0.64

‘B’ 0.71

‘C’ 0.84

‘D’ 1.31


The value of ‘z’ in case of circular pipes is given in Table 4.7


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Table 4.7: Values of ‘Z’ For Different Pipe Beddings

Value of ‘z’ for Fraction of conduit on which lateral pressure acts ‘m’ ‘A’ Class Beddings Other Beddings 0.00 0.150 0.000

0.3 0.743 0.217

0.5 0.856 0.423

0.7 0.811 0.594

0.9 0.678 0.655

1.0 0.638 0.638


Negative Projective Conduits

The load factor for negative projecting conduits may be determined by the

equations (6.15) and (6.16) with value of k of 0.15. Provided the side fills are

well compacted.

Imperfect Trench Conditions

The equations for positive projecting conditions will hold good for those conditions

as well.

Conduits under Simultaneous Internal Pressure and External Loading

Simultaneous action of internal pressure and external load gives a lower

supporting strength of a pipe than what it would be if the external load acted

alone.

If the bursting strength and the three edge strength of a pipe are known. The

relation between the internal pressure and external loads which will cause failure

may be computed by means of the formula

t = T (1-s2)

S …………………………………………………….6.17

where

t = internal pressure in kg/cm2 at failure when external load is

simultaneously acting

T = bursting strength of a pipe in kg/cm2 when no external load is

simultaneously acting

s = three- edge bearing load at failure in kg/linear metre when there is no

internal pressure simultaneously acting.

Relationship between the different elements in structural design

The basic design relationship between the different design elements are as

follows for grid pipes Ultimate three edge bearing strength

Safe working strength = Factor of safety

Safe field supporting strength = Safe working strength x Load factor


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Recommendations

• The factor of safety recommended for concrete pipes for sewers is ‘1.5’ which

is considerably less as compared to that for most engineering structures which

have a factor of safety of atleast 2.5. As the margin of safety against the

ultimate failure is low, it becomes imperative to guarantee that the loads

imposed on sewer pipes are not greater than the design loads for the given

installation conditions. In the order to achieve this objective the following

process are recommended.

• Width of the trench specified for a particular job should be minimum in

consonance with the requirements of adequate working space to allow access

to all parts and joints of pipes.

• Specification should lay proper emphasis on the limit of the width of trench to

be adopted in the field which should not exceed that adopted in the design

calculations. Any deviations from this requirement during the construction

should be investigated for their possible effect on the load coming on the pipe

and steps should be taken to improve the safe supporting strength of pipe for

this condition of loading by adopting suitable Bedding or such other methods

when necessary.

• The field Engineer should keep in touch with the Design Engineer throughout

the duration of the project and any deviation from the design assumptions

due to the exigencies of work should be immediately investigated and

corrective measures taken in time.

• All pipes used on the work should be tested as per the IS specifications and

test certificates of the manufactures should be furnished for every

consignment brought to the site.

• Whenever shoring is used, the pulling out of planks on completion of work

should be carried out in stages and this should be properly supervised to

ensure that the space occupied by the planks is properly backfilled.

• Proper backfilling methods both as regards to selection of materials, methods

of placing and proper compaction should be in general agreement with the

design assumptions.

4.7 Sewer Appurtenances

4.7.1 Manholes Manholes are to be provided at all junctions, change of sewer size, gradient and

direction. As per the general practice the spacing of manhole is kept between 25

to 40 mt for all diameters. Spacing of Manholes adopted is as follows:

a) Pipe dia of 300 mm – 450 mm = 30 m

b) Pipe dia of 500 mm – 900 mm = 40 m

c) Pipe dia of 1000 mm – 1800 mm = 50 m


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However, additional manholes are to be provided on junctions of the street

avoiding standard distance.

4.7.2 Scrapper Manholes For sewers of diameters 600 mm and above, scraper manholes can be provided

at major junctions and at 135m centre to centre. Scraper manhole openings will

be of minimum 900 to 1200mm sizes to permit lowering of sewer cleaning

equipment.

4.7.3 Ventilation Shafts Ventilation shafts need to be provided at the start of the sewer and along the

sewers at about 225 m interval. M.S. Ventilation shafts are recommended, as

they are long lasting and chances of theft are minimal.

4.8 Sewage Pumping Stations

4.8.1 Types The following types of pumps are used for sewage

Horizontal centrifugal pumps with flooded suction installed in the dry well

Vertical pumps with pumps submerged in the wet well and the motor on a high

level platform with connecting vertical shaft.

Fully submersible pumps where motor is housed in the pump in submerged unit.

4.8.2 Design Considerations Solid handling capacity: Inspite of the provision of screens, the impeller

clearance has to be sufficient to handle solids entering the pumps accidentally.

Usually, horizontal centrifugal pumps can handle solids upto 75 mm size and

submersible pumps can handle solids upto 100 mm.

Ease of Installation: Horizontal pump installations are more rigid and

complicated where as submersible pump installation is flexible and simple.

Cost of civil works: Horizontal pumps require separate dry well and civil works

are expensive. Submersible installations are cheaper.

Land requirement: Land requirement is less for submersible pump installation.

Easy to Operate and Maintenance

Less Power Intensive


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4.9 Sewage Treatment Plant

Typical Flow Diagram for Sewage Treatment Plant

4.9.1 Plant and Process Design Parameter

Sr. No

Item

Conventional activated Sludge process

Conventional Trickling Filter

Oxidation Ditch

Facultative aerated lagoon

Waste stabilisation ponds

UASB reactor process

1 Performance BOD removal (%)

85-92 80-90 95-98 75-85 75-85 75-85

Coliform removal(%)

60-90 60-90 60-90 60-90 60-99.9 Insignificant

2

Land Requirement(m2/capitat excluding post treatment)

0.18-0.25 0.20-0.30 0.15-0.20 0.30-0.40 2.0-2.8 0.15-0.20

3

Energy Requirement KWH/Person/Year

12-15 7-11 16-19 12-15 nil -

4 Equipment Requirement

Aerators, recycle pumps, scrapers, Thickener, Digester, Dryer, Gas equipment

Trickling filter arms, recycle pumps, sludge scrappers, thickeners, digester equipments,

Aerators, recycle pimps

Aerators nil Pumps, gas collection equipment


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Sr. No

Item

Conventional activated Sludge process

Conventional Trickling Filter

Oxidation Ditch

Facultative aerated lagoon

Waste stabilisation ponds

UASB reactor process

5 Level of Supervision

Skilled Skilled Simplest

Simpler than activated sludge

6 Cost(in lacs) Capital cost /MLD

35 25 15 9 24

O&M Cost/MLD/Year

1.5 0.75 1.25 1.25 0.72

Source: Master Plan of Somdrup Jonkha Bhutan, 2007

General The Plant shall be designed, selected and installed taking into account site

ambient conditions, local conditions and location.

The following site conditions shall apply

• ambient temperature (plant room) - 35oC

• annual average temperature - 30oC

• Relative humidity (maximum) - 75%

• Altitude - 125 m

• site conditions - semi-arid

The plant shall be designed for an ambient temperature of 40º C and making due

allowance in his designs for the increased temperatures experienced by Plant

exposed to direct sunlight.

Works Life Expectancy The life expectancy at the treatment plant

design is as follows:

• concrete structures 60 years;

• mechanical plant 25 years;

• electrical plant 25 years;

• buried earth electrode systems 50 years;

• control panels 25 years;

• external instrumentation systems 15 years;

• Computer systems 12 years.

4.9.2 Process Design Parameters

A. Elevated Inlet chamber and plant by-pass

Inlet chamber shall be adequately sized to receive sewage from pumping main

and to provide plant bye pass having peak hydraulic carrying capacity of 114.75

mld plant bypass shall be designed to attain 0.9 m/sec to 1.5 m/sec velocity at

peak flow duly considering the available hydraulic head at the plant from inlet


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chamber to discharge point. Hydraulic Detention Time shall be 60 seconds

minimum at peak flow.

B. Elevated screen chamber

a) Peak flow (Design flow) 114.75 mld

b) Average flow 51 mld

c) Number of Screens

Two screen in parallel, each

to deal with peak flow and

incline at 60° to horizontal

and mechanically cleaned/

raked.

d) Number of channels Two screen channels, each

designed for peak flow.

e)

Velocity in approach

channel during average

flow (minimum)

0.4 m/ sec

f) Max velocity through

screen at peak flow 1.2 m/sec

g)

Flats of screen Tapered in

the direction of flow (front

x back x depth )

10 mm x 8 mm x 75 mm

h) Clear opening between two

flats at back 12 mm

i) Free board above TWL 0.5 m

Source: DPR of Drainage and STP for Rajkot City

C. Elevated Grit Chamber a) Peak flow 114.75 mld


c) Number of grit chambers

Three grit chambers to be

designed for handling the 1.5

times the peak flow and (two

working and one standby unit of

similar size).

2+1 Nos each

for half of

peak flow

d) Specific gravity of grit 2.45

e)

Size of particles equal to and

above which are to be removed

100%

0.15 mm

f) Quantity of grit in sewage 0.1 m3/m1

g)

Horizontal velocity in grit

chamber not to exceed at peak

flow

0.30 m/sec

h) Temperature of sewage

(design) 18 °C


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i) Filed correction factor for

surface loading 0.80

j) Detention time (minimum) 60 sec

k)

Minimum depth of wall in grit

chamber at outlet weir

excluding corner filling of 300

mm)

0.9 m

l) Organic matter in washed grit

not to exceed 3 %

m) Free board above – TWL 0.5 m


D. Primary Settling tank a) Peak flow 114.75 mld


c)

Excess sludge, filtrate and supernatant

shall be added in distribution chamber

of primary settling tank as per layout

plan and grease and oil will be

separately disposed off

d) Number of circular tanks …

Two unit each to deal with

25.50 mld flow plus other

flow (excess sludge, filtrate,

sludge, filtrate,

supernatant)

e) Surface loading (effective) at average

flow + other flow 35 m3/day/m2

f) Surface loading at peak flow 80 m3/day/m2

g)

Detention time at average flow

excluding Hopper bottom volume, but

including other flows

2.25 hours

h) Side water depth minimum (up to top

of weir) 3.0 m

i) Slope of hopper bottom I V to 12 H

j) Weir loading at avg. flow + other flows

(not to exceed) 150 m3/day/m

k) Weir loading at peak flow + other flows

(not to exceed) 370 m3/day/m

l) BOD 3 @27 ˚C removal in PST (min) 40 %

m) Suspended solids removal in primary

settling tank (min) 60 %

n) Solids concentration in primary sludge 5 %



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Note:

a)

All piping/channels and launder of primary settling

tank shall be designed for peak flow including any

other flows as per layout plan with minimum

velocity of 0.6 m/sec at average flow.

b)

All peripheral launder of primary settling tank shall

be designed for peak flow with velocity of 0.9 m/sec

and any other flow as per layout plan.

c) Free Board of peripheral launder (minimum) 0.5 m

d) Free fall in peripheral launder /trough with respect

to weir crest (bottom-most portion of V Notch). 50 mm


E. Aeration Tank a) Peak flow 114.75 mld


c) Number of tanks

One tank with two

compartments to deal with

avg. flow plus all other flow

as per layout plan.

d)

Detention time at average flow +

25% of avg. flow return sludge +

all other flows as per layout plan.

Six hours minimum

f) Kg BOD 3 27°c loading/m3 of tank

volume (check) 0.3 – 0.6

g) MLSS in aeration tank 2000 mg/1

h) MLVSS in aeration tank 80% of MLSS

i) Food to micro-organism ratio (F/M)

(i.e. kg BOD5 @ 27°C/kg MLVSS) 0.2-0.4

j) Sludge age (θc) minimum 10 days

k) Free board above TWL 1.0 m

l) Oxygen requirement 1 kg O2 /kg of BOD 3 @

27° c removed

m) Oxygen transfer required at

standard condition (min) 2.0 Kg/ kW. Hr.

n) Dissolved oxygen to be maintained

in the aeration tank (minimum) 1.5 mg/1

o) Field transfer rate of aerators

(minimum) FTR 1.22 kg O2/KWhr

p) Mixing requirement of KW 0.015-0.026 KW/m3


All other flow reaching the tank as per layout plan shall be considered in the design.


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F. Secondary Settling tank a) Peak flow 114.75 mld


c) Number of circular tanks & their

capacity requirement

Two units each to deal with

25.5 mld flow + return sludge

+ filtrate + supernatant +

excess sludge. [as per layout

plan]

d)

Surface loading (effective) at

average flow + all other flows +

return sludge.

28 m3/day/m2

e)

Detention time excluding hopper

bottom volume but including other

flows (minimum)

2 Hours

f) Side water depth (minimum) up to

top of weir 3.5 m

g) Hopper bottom slope 1 V to 12 H

h)

Weir loading at avg. flow + other

flows (by providing weirs as

required).

Upflow velocity near weir at

average flow (not to exceed)

185-370

7

m3/day/m

m3/hour/m

i) Solids concentration in secondary

sludge 1%

j) Solids loading rate at average flow

based on MLSS 70-140 kg/day/m2

k) Solids loading rate at peak flow

based on MLSS (not to exceed) 210 kg/day/m2


a)

All pipes/channel to secondary settling tanks shall

be designed for peak flow including other flows as

per layout plan

b)

All weir and troughs of secondary settling tanks

shall be designed for peak flows as per layout

plan with velocity of 0.9 m/sec.

c) Free board (minimum) 0.50 m

d) Free fall in peripheral launder /trough with respect

to weir crest (bottom-most portion of V Notch). 0.05 m



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G. Digesters

a) Raw sludge (primary + secondary) solids concentration

4 %

b) Volatile solids 50%

c) Specific gravity of raw sludge 1.07

d) Volatile solids destroyed during digestion

(min) 60 %

e) Temperature of digestion 30 °C

f)

Detention time for digestion @ stated

Temperatures

Addl. HRT for monsoon period

30

15

days

days

g) Solids concentration in digested sludge 8 %

h) Number of units required 2 nos.

i) Solids loading 0.75 kg VSS/day/m3

j) Bottom hopper slope 1 V to 4 H

k) Mixing system Gas mixing

unconfined

l) Gas flow required for gas mixing

Compressor operating capacity

0.005

1

m3/m3.min(min)

m3/hr.m2 (min)

m) Velocity gradient 50-80 Sec-1

n) Sludge circulation velocity 0.05-0.10 m/sec

o) Power level to be maintained 5 Watts/m3 (min.)

p) Gas lances required 15-35 Sq. mt / No.


H. Gas Holder

a) Gas production in sludge

digester 0.9

m3/kg of VSS

destroyed

b) Gas is to be utilized in plant. Future (not in present

contract)

c) Storage capacity of gas. 1 day

d) Gas to be burnt 100%

e) Number of units required 2 nos


I. Sludge Drying Beds a) Preferred size of each bed. 20 m x 20m

b) Depth of digested sludge application on the drying

beds. 0.3 m

c) Cycle time of drying including restoring to original

state of original state of bed. 12 days

d) Solids concentration of dried sludge prior to

application on bad. 8 %

e) Moisture concentration of dried sludge amenable

for spading and carting away. 40 % at 40 ºC

f) Standby beds required 2 nos.


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J. Raw sludge pumping station a) Sludge concentration 5 %

b) Specific gravity of sludge 1.07

c) Actual pumping hours for sludge pumping per

day As required hrs/day

d) Minimum diameter of pumping main to avoid

chock age. 200 mm

e)

Hydraulic Retention Time for raw sludge during

maximum concentration of 2000 mg/l at peak

flow

2 hour

f) SWD for storage sump below pipe invert level 2 m


K. Return sludge pumping station

a) Quantity of return sludge Up to 75% of avg. Flow + excess

sludge

b) Concentration of solids in

return sludge 1 %

c)

Hydraulic Retention Time for

return sludge during normal

rate of pumping (25%)

1 hour

d) Specific gravity of return

sludge 1.02

e)

Minimum diameter of

pumping main to avoid chock

age.

200 mm

f) SWD for storage sump below

pipe invert level 2 m


L. Filtrate pumping station a) Solid concentration in filtrate 200-300 mg/1

b) Minimum diameter of pumping

main 150 mm

c) SWD for storage sump below pipe

invert level 2 m


M. Pipeline

a) Pipeline for Main plant by pass from inlet chamber to final disposal point

b) Pipeline from distribution chamber ahead of PST to main plant bypass


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c) Pipeline from distribution chamber ahead of aeration tank to main plant bypass

d) Treated effluent pipeline from SST to common collection chamber and pipeline from

common collection chamber to final disposal point

e) Channel From inlet chamber to screen chamber

f) Channel from Screen chamber to grit chamber.

g) Channel from Grit chamber to parshall flume.

h) Pipeline from distribution chamber of PST to PST Central feed well

i) Pipeline from PST outlet to distribution chamber of aeration tank

j) Pipeline from outlet of Aeration Tank to of central feed well SST

k)

Washout for aeration tank shall be provided and connected to bypass line for

emptying the unit by gravity with a minimum size of 450 mm dia DI, K-9 class

pipeline with valve of same size


Standard indicated in table below are for treated sewage to be disposed into

inland water bodies e.g. River However these standards vary as per the

geographical location of the town

Sample Compliance Requirement

Effluent from PST BOD < 150 mg/1

SS < 250 mg/1

Effluent from SST

BOD < 20 mg/1

SS < 30 mg/1

pH 6 to 9


Refer Guidelines and Specification for Civil, Mechanical and Electrical works which are provided in CD

5.0 Storm Water Drainage

5.1 Introduction The purpose of providing storm water drains is to carry the rainfall (storm) runoff

from the terraces, paved courtyards, footpaths, roads etc. of the developed area;

so that the occurrence of flooding is reduced to the acceptable frequencies.

Storm run off is that portion of the rainfall which drains over the ground surface.

The estimation of such runoff reaching the storm water drains therefore is

dependent on the intensity and duration of rainfall, characteristics of the drainage

area and time required for such flow to reach the storm water drains.

Storm water drains are not designed for the peak flow of rare occurrence of

rainfall such as once in 10 years or more; but it is necessary to provide sufficient

capacity to avoid too frequent flooding of the drainage area. There may be some

flooding when the precipitation exceeds the design value, which has to be


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permitted. The frequency of such permissible flooding may vary from place to

place, depending upon the characteristics of the drainage area. Though such

flooding causes inconvenience, it may have to be accepted once in a while,

considering the economy in the cost

The estimation of such runoff reaching the storm water drains therefore is

dependent on:

• Intensity and duration of rainfall

• Characteristics of the drainage area

• Time required for such flow to reach the storm water drains.

Estimation of Run off

The runoff reaching the drain is given by the rational method viz.

Q = 10 CIA

Where,Q is the runoff in m3 / hour

C is the coefficient of runoff

I is the intensity of rainfall in mm / hour

A is the area of drainage zone in hectares

Storm frequency considered for the design is adopted as “frequency of once a

year”.

In absence of data from IMD, based on general equation by British Ministry of

Health, the intensity of rainfall adopted for the design is 20 mm / hour and the

duration of storm (t) in minutes, expressed by the mathematical formula adopted

is as under :

i = 1000

t + 20

Source: Sanitary Engineering by Prof. Vinayak N. Gharpure

From this formula, for different values of intensities, corresponding values of‘t’

are worked out. These values of ‘i’ &‘t’ are plotted on graph and the values of

intensity (i) can be determined for any given time of concentration (tc) i.e.

tc = inlet time + time of flow in the drain

tc = t(i) + t(f)

The portion of rainfall which finds its way to the drains is dependent on the

imperviousness and the shape of the drainage area, apart from the duration of

storm. The percentage of imperviousness for built-up area is considered as 90%

and for the open area is considered as 20%. Therefore, the weighted average

imperviousness of the drainage area for the flow, concentrating at a point is

estimated.


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Diameter wise Length of Storm Water Drain Pipes in meter

Besides, as required by the client, the storm water drains are proposed on both

sides of the roads; so that road cutting is avoided while giving consumer

connection to the plot holders. For the collection and disposal of storm water,

RCC pipes are proposed as storm water drains.

Manholes are proposed on straight stretches of pipe drains at distance of 30 m,

staggered on both sides of drains. Besides, additional manholes are also

provided at change of direction of drains as well as size of drainpipes. Catch pits,

outlet structures are also proposed at various locations to collect and discharge

the storm water in the drainage system.

5.2 Design Methodology The following steps are followed for design of storm water drainage:

• First of all the length and area to be served by each pipe is worked out.

• Total area is assumed as divided in two parts; 50% built-up area and 50%

open area.

• The percentage of imperviousness for built-up area is considered as 90% and

for open area is considered as 20%. From this total impervious area is found

out.

• Time of inlet (TI) is taken 25 minutes (Range is 5 to 30 minutes in CPHEEO

Manual).

• Time of flow (TF) is found out considering velocity of flow 1 m/s.

• Time of concentration (TC) = TI + TF.

• From graph of I TC, I is found out and from graph of C TC, C is found

out. (See Annexure No. 1 & Annexure No. 2)

• From all this runoff reaching the drain is given by Q = 10 CIA.

Where Q = Runoff in m3/hour

C = Coefficient of runoff

I = Intensity in mm / hour

A = Area in hectares

• From Q diameter is selected depending upon the availability of ground slope

and Manning’s Formula.

Q = 1 x (0.2693 x 10-6) D8/3 x S 1/2

n

Where n = Manning’s co-efficient of roughness (consider 0.015)

D = Diameter of pipeline in mm

S = Slope of pipeline

Q = Flow in MLd


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5.3 Design of under ground Strom Water Network

5.3.1 Modified Rational Method To design pipe or channel sizes and gradients using a version of the Rational

Method. Gradients are designed to give adequate self-cleansing velocities and dry

weather or storm flows. Sizes are designed using the rational formula to take the

peak flows. The system may include overflow structures and detention storage.

The program can calculate the required volume of storage. This is the simplest

method in the package.

In the event of less scanty/less rainfall data availability the rational formula has

given should be used for design of storm water drainage network.

5.3.2 Hydrograph Design Method To size pipes or channels for observed or synthetic rainfall events in a network

with defined layout and levels. The network may include overflows, storage tanks

and pumping stations. The method is a hydrograph routing method, which

designs the pipes to take the peak flow.

5.3.3 Simulation Method To simulate time varying flow with surface flooding or surcharge for observed or

synthetic rainfall events in an existing or designed sewerage network. The

network may include overflows, storage tanks pumping stations, and flap valves.

The models, which go to make up the methods, are shown in the table 5.1

Table 5.1: Models for Different Methods of under ground storm water drainage

Method Model

Rational Hydrograph Simulation

Rainfall

Intensity -

duration

relationship

Rainfall hyetographs

Runoff UK Wallingford runoff model

Fixed runoff coefficients SCS runoff model

Overland flow Time of entry Linear reservoir model

Pipe and

Channel

peak flows

pipe full velocity

Muskingum-

Cunge

Muskingum-Cunge Surcharge

Backwater

Ancillary

structures

Overflows

On-line storage

Overflows

Pumps

On-line and

Off-line

storage

Overflows Pumps

On-line & Off-line storage

Tide levels

Flap valves

Source:


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6.0 Solid Waste Management

6.1 Key Features – MSW Rules 2000 The government of India / Ministry of Environment and Forest have modified

Municipal Solid Waste (Management and Handling Rules) 2000 for the effective

and scientific management of solid waste.

6.2 Composition of waste Solid waste generation is mainly from domestic, trade, commercial, agricultural

and industrial activities and from public services. In Indian cities, it is a

combination of various heterogeneous waste materials— a mixture of vegetable

and organic matter and inert matter such as glass, metal, stones, ashes, textiles,

wood, grass, and so forth. Its main sources are residential premises, business

establishments and street sweepings.

The composition and quantity of per capital generation of waste varies with living

standards of population viz. high/low/middle are presented in table 6.1

Indian mixed waste has a large proportion of compostable material and inert

materials. The Central Public Health and Environmental Engineering Organization

(CPHEEO) have published a comprehensive manual on municipal solid waste

management for the guidance of ULBs. Physical and Chemical characteristics of

municipal solid waste in Indian cities are presented in table 6.1 and table 6.2

Table6.1: Physical Characteristics of Municipal Solid Wastes in Indian Cities

Population Range (in million)

Number Of Cities Surveyed

Paper

Rubber, Leather And Synthetics

Glass Metals Total Compostable matter

Inert

Percentage

0.1 to 0.5 12 2.91 0.78 0.56 0.33 44.57 43.59

0.5 to 1.0 15 2.95 0.73 0.35 0.32 40.04 48.38

1.0 to 2.0 9 4.71 0.71 0.46 0.49 38.95 44.73

2.0 to 5.0 3 3.18 0.48 0.48 0.59 56.67 49.07

> 5 4 6.43 0.28 0.94 0.8 30.84 53.9

Source: Background material for Manual on SWM, NEERI, 1996


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Table 6.2: Chemical Characteristics of Municipal Solid Wastes in Indian Cities


Number Of Cities Surveyed

Moisture Organic matter

Nitrogen as Total Nitrogen

Phosphorous as P2O5

Potassium as K2O

C/N Ratio

Calorific value* in kcal/kg

Percentage

0.1 to 0.5 12 25.81 37.09 0.71 0.63 0.83 30.94 1009.89

0.5 to 1.0 15 19.52 25.14 0.66 0.56 0.69 21.13 900.61

1.0 to 2.0 9 26.98 26.89 0.64 0.82 0.72 23.68 980.05

2.0 to 5.0 3 21.03 25.6 0.56 0.69 0.78 22.45 907.18

> 5 4 38.72 39.07 0.56 0.52 0.52 30.11 800.7


Quantity of waste

India produces about 42 million tons of urban solid waste annually. The current

municipal solid waste generation is estimated to be approximately 0.4 kilograms

per person per day. Waste generation ranges from 0.2 kilograms to 0.6 kilograms

per capita per day in cities ranging from 1 lakh to more than 50 lakh population.

Table 6.3 Quantity of Municipal Solid Waste in Indian Urban Centres


Number Of Urban Centres (Sample)

Total population (in million)

Average per capita value (kg/capita/day)

< .1 328 68.3 0.21

0.1 to 0.5 255 56.914 0.21

0.5 to 1.0 31 21.729 0.25

1.0 to 2.0 14 17.184 0.27

2.0 to 5.0 6 20.597 0.35

> 5 3 26.306 0.5


Density of waste

Knowledge of the density of a waste i.e. its mass per unit volume (kg/m3) is

essential for the design of all elements of the solid waste management system

viz. Community storage, transportation and disposal. For example, in high income

countries, considerable benefit is derived through the use of compaction vehicles

on collection routes, because the waste is typically of low density. A reduction of

volume of 75% is frequently achieved with normal compaction equipment, so that

an initial density of 100 kg/m3 will readily be increased to 400 kg/m3. In other

words, the vehicle would haul four times the weight of waste in the compacted

state than when the waste is loose. The situation in low-income countries is quite

different: a high initial density of waste precludes the achievement of high

compaction ratio. Consequently, compaction vehicles offer little or no advantage

and are not cost-effective.


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Moisture Content

Moisture content of solid wastes is usually expressed as the weight of moisture

per unit weight of wet material.

Moisture Content (%) =

Wet weight – dry weight x100

wet weight

A typical range of moisture contents is 20 – 45% representing the extremes of

wastes in an arid climate and in the wet season of a region having large

precipitation. Values greater than 45% are however not uncommon. Moisture

increases the weight of solid waste and therefore the cost of collection and

transport. Consequently, waste should be insulated from rainfall or other

extraneous water.

6.3 Collection of Municipal Solid Waste (MSW) Following steps are involved in collection of Solid Waste:

• Littering of Municipal Solid waste shall be prohibited in cities, towns and urban

areas.

• Organize collection of waste from houses (including those in slums and

squatter settlements), hotels, restaurants, office complexes, and commercial

areas through any of the methods such as community bin collection, door to

door collection, collection on regular pre-informed timings and schedule by

using bell ringing/musical vehicle.

• Manage biodegradable wastes from slaughter houses, vegetable markets, and

so on by recycling them.

• Avoid mixing biomedical wastes and industrial wastes with municipal solid

wastes and complying with separate rules prescribed for them.

• Collected waste shall be transferred to community bin through containerized

hand carts or other small vehicles.

• Horticultural and construction/demolition waste or debris shall be disposed off

following proper norms.

• Waste of any sort should not be burnt.

• Municipal authority shall notify waste collection schedule and method to be

adopted for public benefit in a city or a town.

6.4 Segregation of Municipal Solid Waste • Encourage citizens to segregate waste at the source and promote recycling or

reuse of segregated materials by organizing awareness programmes.

• Ensure community participation in waste segregation by arranging quarterly

meetings with representatives of local residents’ welfare associations and

NGOs.


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6.5 Storage of Municipal Solid Waste The municipal authorities are required to establish and maintain hygienic and

sanitary

• storage facilities by taking these steps:

• Create storage facilities in accordance with waste generation and population

densities and should be placed such that it can be easily accessed by the

users.

• Not exposing storage facilities to the open environment and maintaining them

in an aesthetically acceptable and user-friendly manner.

• Storage facilities are to have a design that is easy to operate for handling,

transfer, and transport of waste. Bins for storage of biodegradable waste shall

be painted green, for recyclable waste the bins shall be painted white and for

storage of other wastes the bins shall be painted black.

• Manual handling of waste is prohibited. If unavoidable due to constraints, it

should be carried out with precaution and due safety of workers should be

ensured.

6.6 Transport of Municipal Solid Waste • Vehicles used for transportation of waste shall be covered so as to prevent

scattering of waste, being non visible to public, not creating nuisance due to

bad odour ad remaining unexposed to open environment.

• Storage facilities set up my municipal authorities shall be daily attended for

clearing of wastes.

• The bins or containers wherever placed, should be emptied and/or replaced

before they start overflowing.

• Transportation vehicles shall be designed such that multiple handling of waste

prior to its disposal is avoided.

6.7 Processing of Municipal Solid Waste Municipal authorities shall adopt suitable technology or combination of such

technologies to make use of waste thereby lessening the burden on landfills.

Following criteria shall be adopted:

• Biodegradable waste shall be processed by composting, vermin-composting,

anaerobic digestion or any other biological processing for stabilizing the

waste. The end product of any of these processes shall comply with the

standards as mentioned in Schedule IV of MSW Rules 2000.

• Mixed waste containing recoverable resources shall follow the route of

recycling, incineration with or without energy recovery.


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6.8 Disposal of Municipal Solid Waste • Land filling shall be restricted to non-biodegradable, inert waste and other

waste that are not suitable either for recycling or for biological processing.

• Land filling shall be carried out for residues of waste processing facilities as

well as pre-processing rejects from waste processing facilities.

• Land filling of mixed waste shall be avoided unless the same is found

unsuitable for waste processing.

6.9 Design System for SWM • Calculate household in the area based as per Capita Waste Generation

Calculate weight of waste generated from H/H = Population × per capita

waste

• Decide density of Waste generated.

• Calculate Volume = Weight waste ÷ Density

• Segregate waste 40% Wet and 60% Dry

• Litter bins at 50 to 100 mt. distant from H/H.,

• 1 tricycle for 300 to 400 shops required.; 1 handcart for 15 to 50 H/H ; 1 Auto

– tripper for 1000 H/H

6.10 Street sweeping • Derive the Total road length and covert it in single lane.

• 1 labour can sweep 750 mt. per single lane

• Primary container capacity to be taken 40 liter to 100 liter.

• Calculate primary collector container

6.11 Secondary storage Capacity of Secondary container

• 1 cmt volume

• 2 cmt volume

• 3 cmt volume

• 4 cmt volume

• Calculate secondary containers

= [(Projected Population × 0.210)÷Density]

÷ Decided container

6.12 Sample Financial Estimates for implementation of Solid Waste Management Plan • Total population (2001) : 30,871 (Household size : 4.5)

• Total population (2005) : 38,097 ( as per above HH size)

• Total Households (HH’s) : 8466 (Source: Economical Survey, NSSO,2002)


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• Non-Slum HH’s : 7485 (Source: Property Tax data, 2005)

• Slum HH’s : 981 ( Above No 3. – No. 4 )

Solid waste generation (2005)

• Assuming one person generates 220 gm / day : 8.38 tonnes /day

• Assuming 30 % extra for other institutes : 10.89 tonnes/day

A. Total waste generation: 11 Tonnes per day The Solid Waste management includes the following components:

• Door to door waste collection from all residential and commercial area

• Street sweeping

• Secondary storage of wastes at fixed locations on streets

• Transportation of waste from secondary storage points to the landfill site

• Disposal, Composting of waste

B. Door to door waste collection from all residential and commercial area

a. Collection of waste from non-slum residential HH’s

In this areas, Tricycles and Auto tippers will be provided.

Total HH = 7485

One Auto tipper can collect waste from 1000 HH’s.

If 3 auto tippers are provided : no of HH covered : 3000

One Tricycle can collect waste from 300 HH’s.

No of Tricycles required = 4485 / 300 = 14.95 = 15

Auto tipper = 3

Tricycle = 15

Workers = 18

b. Door to door waste collection from slum areas

In this area, community bins of capacity 40 liters will be provided for every 15

HH’s.

No of HH’s = 981

No of community bins required = 981 / 15 = 65.4

To empty those bins, 3 handcarts will be provided.

Handcarts = 3

Workers = 3

Community bins = 65

c. Door to door collection from commercial areas

In this area, tricycles will be provided which will cover, 400 shops each.

Total shops (commercial properties) = 1773

(source: Property tax data, 2005)


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No of tricycles required = 1773 / 400 = 4.43 = 5

litter

gene

Provi

No o

C. St

The

requi

Total

One

RoadClasA

B

C

D

W

H

Br

Su

Co

D.Se

Assu

Dry w

Provi

collec

collec

Num

4 cum

2 cum

Tricycles = 5

Workers = 5

Assuming 3 km stretch of roads covered by commercial area, where

bins of 40 liters capacity each, will be provided to collect the waste

rated by the passer-by.

ding one litterbin per 60 meters of road length.

f litterbins required = 3000 / 60 = 50 nos.

Litterbins = 50

reet Sweeping:

roads in the whole town will be divided into 4 categories as per the

rement of sweeping:

road length in town: 65 km (including NH no 8)

Sweeper will sweep 1000 RML (running meter length) of road per day.

s

Frequency of cleaning

RML for sweeping KM

Workers required

Daily 12 = 12

Twice a week 18 = (18 * 2 )/6 = 6

Once a week 30 = (30*1)/6 = 5

Once a fortnight 5 = (5 * 0.5 )/6 = 0.41 = 1

orkers = 24

andcarts = 24

ooms = 24

padi, patra = 24

mmunity bins = 65

condary storage of wastes at fixed locations on streets

ming 60 % of the total waste generated to be wet waste = 6.6 tonnes/day

aste = 4.4 Tonnes/day

ding containers of size 4 cum (storage capacity = 1.6 tonnes) for wet waste

tion and of size 2 cum (storage capacity = 0.8 tonnes) for dry waste

tion.

ber of containers required =

size : 4 + 2 (extra for replacement) = 6

size : 6 + 2 (extra for replacement) = 8


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E. Transportation of waste from secondary storage points to the landfill

site Two tractors will be deployed for the collection of waste from above containers as well as

bulk generators and other sources as per requirement.

Staff requirement: Existing Staff: 48

Table 6.5: Requirement of Workers

Sr No Activity No of workers

Primary Collection 1 Door to Door collection of waste (Res+com) 18 + 5

2 Waste collection from slums 3

3 Street Sweeping 24

4 Transportation (2 vehicles) 8

5 Absentees (8 %) 4

Total 62

No of workers required = 62 – 48 = 14

Table 6.6: Financial Estimates

Activity Equipment required

No of units required

Rate / unit

Units to be procured

(units required – available)

Total Cost

PRIMARY WASTE COLLECTION DTD Collection – Non-slum HHs

Tricycle 15 7,980 15 1,19,700

Auto tippers 3 1,00,000 3 3,00,000

DTD collection Slum HH

Handcarts (with 6 containers)

3 5,310 3 15,930

DTD collection Commercial

Tricycle 5 7,980 5 39,900

Tractors = 2

Containers:

Size 4 cum = 6

Size 2 cum = 8


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Sub -Total 4,75,530

CONTAINERS

For Wet waste – 4 cum capacity

Container 6 35,000 6 2,10,000

For Dry waste – 2 cum capacity

Container 8 23,000 8 1,84000

Commercial area Litterbins 50 300 50 15000

Slum Area Community bins

65 300 65 19,500

Container placement

Platform 6 2000 6 12,000

Sub-total

4,40,500

STREET SWEEPING Handcarts 24 - -

Brooms 24 30 - -

Supadi Patra 24 35 - -

Sub-total

-

Total

9,16,030

(Please note that the cost Shown above is indicative and may vary from place to

place)

6.13 Design Criteria of Landfill Site Selection • The term ‘landfill’ is used to describe a unit operation for final disposal of

‘Municipal Solid

• Waste on land, designed and constructed with the objective of minimum

impact to the environment by

• Incorporating eight essential components as described by CPHEEO Manual,

2000. This term

• encompasses other terms such as ‘secured landfill’ and ‘engineered landfills’

which are also

• Sometimes applied to municipal solid waste (MSW) disposal units. The term

‘landfill’ can be treated

• as synonymous to ‘sanitary landfill’ of Municipal Solid Waste, only if the latter

is designed on the

• Principle of waste containment and is characterized by the presence of a liner

and leachate collection system to prevent ground water contamination.

• Land filling will be done for the following types of waste:

• Co-mingled waste (mixed waste) not found suitable for waste processing;

• Pre-processing and post-processing rejects from waste processing sites;

• Non-hazardous waste not being processed or recycled.

• Land filling will usually not be done for the following waste streams in the

municipal solid


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Sample Terms of References for Design of landfill site & EIA sets for following

objectives _

• To visit the proposed site, in order to assess whether the site confirms to the

preliminary location criteria for site identification.

• To collect the baseline information on the quantity of waste generation, type

of waste.

• To estimate the land area required for the disposal of the solid waste

generated for 30 years.

• To collect the information in and around the proposed site area limited to

technical aspects such as Air, Surface Water, Soil, Geology, Hydrogeology and

Meteorology To develop surface drainage pattern of the site area at regional

and local level in order to ascertain the surface drainage run-on direction as

well as magnitude

• To develop the Land Use & Land Cover Mapping based on Remote Sensing

IRS-1C

• To carry out the Soil Investigation of the proposed site area.

• To carry out the ambient air quality monitoring in order to ascertain the

background contamination level.

• To carry out the ground water quality monitoring in order to ascertain the

background contamination level.

• To assess potential impacts on all components of environment resulting from

the construction & operation of a Municipal Landfill Facility.

• To carry out Risk Analysis and suggest abatement methods for adverse

environmental impacts likely to occur during the operation of Municipal landfill

facility.

6.14 Case Study of Rajkot DPR The detail design of the proposed site is given below.

The total area required for the land fill site is mainly depends upon

• Present population of the city,

• Population growth rate,

• Quantity of solid waste generated,

• Characteristic of the solid waste,

• The active period for which the solid waste is to be dump,

• Area required for infrastructural facility.

As per 2001 census the population of the Rajkot city is 10.02 lacs which is

growing at the rate of 4.05% annually. As per the house hold survey and actual

quantification at Sold Waste Processing plant, it is observed that waste

generation in Rajkot city is about 325 gm/capita/day. Integrated Solid Waste

Processing Plant at Rajkot is operated by a private operator and is functioning

very efficiently since December -2005. It is recorded that about 68 % of total


Preparation of DPRs

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waste is being processed and converted in to about energy pallet, manure green

cock and eco bricks.

Rajkot Municipal Corporation Landfill

Estimation of the area, height and capacity required for land fill site. ( Pl. refer

CPHEEO Manual Annexure: 17.1 )

• Present population = 1243250

• Average annual Growth rate = 4.00%

• Design active period =30 years.

• Present waste generation = 325 gms /capita /day

• Total waste generation per year at present = 1243250*325*

365/(1000*1000)

• = 147480 tones

• Total biodegradable waste goes to processing

• plant is 68 % of total waste = 147480 *0.68 tones = 100286 tones

• Total non biodegradable waste goes to land fill site is 32% of total waste. = 147480 * 0.32 = 47194 tones

• Estimated rate of increase = 4.00% (as same as popul.Growth ) Proposed life of land fill in year = 30

• Waste generated after 30 years = 153068 tones

• Total waste generated after 30 years = 3003929 tones

• Total volume of waste in 30 years (taking density of the waste is 0.90 t/cum. As inert waste is more) = 3003929/0.85

= 3534034 cum.

• Total volume of daily cover in 30 years

• Taking 10 cm. soil cover for lift ht. 1.5m. = 0.1 * 3534034 = 353403 cum.

• Total volume req. for liner system & cover system assuming 1.5mt. thick liner and 1mt. thick cover system

• and allowing the total ht. 10mt. so taking k = 0.25 = 0.25 * 3534034 = 883508cum.

• Volume likely to become available within 10 years Due to settlement, as

waste having more inert material

• Taking m =0.05 = 0.05 * 3534034 = 176701 cum.

• First estimate of landfill capacity = 3534034+353403+883508-176701

= 4594244 cum.

• Area required for land filling for 10mt. ht. = 4594244/10 = 459424 sq.mt.

• Area required for infrastructural facility = 15% of land filling area

= 0.15 * 459424

= 68914sq.mt.

• Total area required = 459424 + 68914 = 528338 sq.mt.

• Total area required in hectare = 528338/10000 = 52.83 hectare

Say = 53 hectare


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6.15 Environmental Settings

POTENTIAL LANDFILL SITE IDENTIFICATION: In order to select a site for

conducting detailed Environmental Impact Assessment, one site was identified in

the beginning as potential sites for waste disposal. The description of the site is

as under:

• Site No: 01

• Name of the Site: Nakaravadi

• Location: Near Pipalia Village

• Survey No: 222/P

• Total Land Area = 80 Hectare

LOCATION / KNOCK OUT CRITERIA

A Location Criteria given in Guidelines developed for the Management of Municipal

Waste by the Ministry of Urban Development was used to select the site on prima

facie as the first step of site assessment and investigation. The objective of this

step is to exclude the areas, which can be discarded for the setting up of landfill.

The selection of an appropriate site for a landfill is dependent on several criteria,

some of which absolutely exclude the possibility of establishing a landfill in certain

sites.

The following key factors are considered in evaluating these criteria:

• Existing or planned drinking water protection and catchments areas

• High flood prone area

• Area with unstable ground like swamps, moors and / or marshes

• Areas with an extreme morphology (steep slopes, danger of landslides or

avalanches etc.)

• Areas endangered by swallow holes, collapse sites, deep digging etc.

• Areas nearer than 500 meters to populated areas

• Closer than 100 meters to river boundaries

• Areas nearer than 20 km to airports

• National parks, nature protection areas and nature monuments, areas with a

large number of

• fauna and flora Historical, religious or other important cultural sites or heritage


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References

• Manual of Ministry of Road Transport and Highway (MORTH)

• Indian Road Congress (IRC codes)

• IRC 86-1983 Geometric Design for Urban Roads in Plains

• IRC 81-1997 Flexible Road Pavements

• BIS code 2720 various parts for tests on soils

• BIS Code 2386 various parts for tests on aggregates

• Manual on Water Supply and Treatment Plant –third edition revised - 1999



• Manual on Sewerage and Sewage Treatment - second edition 1993



• Municipal Solid Waste (Management and Handling) Rules, 2000

• Manual on Solid Waste Management- First edition 2000 constituted by



• Detailed Project Report for Water Supply of Rajkot Municipal Corporation

• Detailed Project Report for Drainage and STP of Rajkot Municipal Corporation

• Detailed Project Report for SWM of Rajkot Municipal Corporation


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ruidp manual of design

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