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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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Module 2.3: Project Design
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
CPHEEO- Central Public Health and Environment Engineering Organization,
Ministry of Urban Development, New Delhi, G.O.I
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
Source: IRC 37; 1998
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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PAVEMENT COMPOSITION
Bituminous Surfacing
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
Source: IRC 37; 1998
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
PAVEMENT COMPOSITION
Bituminous Surfacing
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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PAVEMENT COMPOSITION
Bituminous Surfacing
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
Source: IRC 86; 1983
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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
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Module 2.3: Project Design
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.
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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
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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
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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),
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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
Source: CPHEEO Manual 1999
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
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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
Source: CPHEEO Manual 1999
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.
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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.
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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
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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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(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
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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
Source: CPHEEO Manual 1999
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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
Must not be detectable in any 100-ml
sample
Must not be detectable in any 100-ml
sample
Must not be detectable in any 100-ml
sample
Must not be detectable in any 100-ml
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
Source: CPHEEO manual 1990
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
Source: CPHEEO manual 1990
@ 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
Source: CPHEEO manual 1990
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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
Source: CPHEEO manual 1990
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.
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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
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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.
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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
Source: CPHEEO manual 1993
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
Source: CPHEEO manual 1993
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 by- pass 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
b) Average flow 51 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
Source: DPR of Drainage and STP for Rajkot City
D. Primary Settling tank a) Peak flow 114.75 mld
b) Average flow 51 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 %
Source: DPR of Drainage and STP for Rajkot City
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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
Source: DPR of Drainage and STP for Rajkot City
E. Aeration Tank a) Peak flow 114.75 mld
b) Average flow 51 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
Source: DPR of Drainage and STP for Rajkot City
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
b) Average flow 51 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
Source: DPR of Drainage and STP for Rajkot City
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
Source: DPR of Drainage and STP for Rajkot City
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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.
Source: DPR of Drainage and STP for Rajkot City
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
Source: DPR of Drainage and STP for Rajkot City
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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Source: DPR of Drainage and STP for Rajkot City
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
Source: DPR of Drainage and STP for Rajkot City
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
Source: DPR of Drainage and STP for Rajkot City
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
Source: DPR of Drainage and STP for Rajkot City
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
Source: DPR of Drainage and STP for Rajkot City
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
Source: DPR of Drainage and STP for Rajkot City
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
Population Range (in million)
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
Source: Background material for Manual on SWM, NEERI, 1996
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
Population Range (in million)
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
Source: Background material for Manual on SWM, NEERI, 1996
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
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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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Module 2.3: Project Design
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
constituted by CPHEEO- Central Public Health and Environment Engineering
Organization, Ministry of Urban Development, New Delhi, G.O.I
• 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
• Municipal Solid Waste (Management and Handling) Rules, 2000
• Manual on Solid Waste Management- First edition 2000 constituted by
CPHEEO- Central Public Health and Environment Engineering Organization,
Ministry of Urban Development, New Delhi, G.O.I
• 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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