ACKNOWLEDGEMENTS Our hearts pulsates with the thrill for tendering gratitude to those persons who helped me in completion of the project

ACKNOWLEDGEMENTS

Our hearts pulsates with the thrill for tendering gratitude to those persons who helped me in
completion of the project.

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The most pleasant point of presenting a thesis is the opportunity to thank those who have
contributed to it. Unfortunately, the list of expressions of thank no matter how extensive is
always incomplete and inadequate. Indeed this page of acknowledgment shall never be able
to touch the horizon of generosity of those who tendered their help to me.

We extend our deep sense of gratitude and indebtedness to our guide Prof. brijesh patel
Department Of Civil Engineering, Samarth College of Engineering and Technology,
Himatnagar for their form attitude, invaluable guidance, keen interest, immense help,
inspiration and encouragement which helped us carrying out our present work.

We are extremely grateful to , Professor and Head of the Department of Civil Engineering,
Samarth College of Engineering and Technology, Himatnagar , for providing all kind of
possible help throughout the during semesters for the completion of this project work.

It is a great pleasure for us to acknowledge and express our gratitude to our classmates and
friends for their understanding, unstinted support and endless encouragement during our
study.

Lastly, we thank all those who are involved directly or indirectly in completion of the present
project work.

PATEL CHIRAG 110880106076
DABHI PUSHPARAJ 130883106002

Page 1

ABSTRACT

Rain water harvesting the small – scale collection and storage of runoff for irrigate
agriculture .It is use to increase in ground water level and improve the ground water
quality .Water harvesting is the activity of direct collection of rain water .Which can
be stored for direct use or can be reached in to the ground water.

Keywords:
Rain Water , Harvesting , Tank , Pump , Pipe Line

Page 2

CONTENTS
Page No.
Abstract 2
Acknowledgement 1
List of figures 5
List of table 5
CHAPTER – 1 INTRODUCTION …………………………………………………….. 6
1.1 INTRODUCTION ………………………………………………… 7
1.1.1 Features of Rainwater Harvesting …………………………… 7
1.2COMPONENTS OF RAINWATER HARVESTING SYSTEM …… 8
1.2.1. Catchments …………………………………………………. 8
1.2.2. Coarse Mesh …………………………………………………. 8
1.2.3. Gutters ……………………………………………………….. 9
1.2.4. Conduits ……………………………………………………… 9
1.2.5. First-flushing …………………………………………………. 9
1.2.6. Filters ………………………………………………………… . 9
1.2.7. Storage Facility ……………………………………………….. 9
1.2.8. Recharge Structure ……………………………………………. 10
1.3. STUDIES CARRIED OUT GLOBALLY ……………………………… 10
1.4. STUDIES CARRIED IN INDIA ……………………………………….. 11
CHAPTER – 2 LITERATURE REVIEW …………………………………… 13
CHAPTER – 3 OBJECTIVE OF RAINWATAR HARVESTING AT
LODRA SCHOOL ……………………………………….. 15
CHAPTER – 4 STUDY AREAS & DATA COLLECTION ……………….. 17

4.1. Study area ………………………………………………………………… 17
4.2. Data collection ……………………………………………………………. 18
4.2.1. Rainfall Data Collection ………………………………………. 18
4.2.2. Determination of catchment area …………………………19

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CHAPTER – 5 Methodology …………………………………………………… 21
5.1. Hydrological Analysis ……………………………………………………… 21
5.2. Methods for storage of harvested rainwater in tank ……………………….. 23
5.2.1. Rationing Method (RM) ………………………………………… 24
5.2.2. Rapid Depletion Method (RDM) ……………………………….. 24
5.3. GIS Analysis ………………………………………………………………. 25

CHAPTER – 6 Optimistic determination of size & types of tank …………….26
6.1. General …………………………………………………………………….26
6.2. Computation of Volume of Runoff per year ………………………………..27
6.3. Optimum dimension of tank ………………………………………………..30
6.4. Types of tank ……………………………………………………………….31

CHAPTER – 7 Detail analysis & designing of rainwater harvesting system
component ……………………………………………………………32
7.1 Analysis & Design Of underground Sump………………………………….33
7.2. Detail cost estimation of sump (underground tank)………………………..42
7.3. Gutter design…………………………………………………………….…43
7.4. First flush mechanisms……………………………………………………..44
7.5. Filtration……………………………………………………………………45

CHAPTER – 8 Results ……………………………………………………………. 46

8.1. Optimum location of tank /underground reservoir recharging point………46
8.2. Rainwater harvesting potential of different building at
Lodra school…………………………………………………………..47
8.3. Detail monthly hydrological analysis of all building ……………………..48
8.4. Dimensions of tank & cost of construction ……………………………….49
8.5. Calculation of number of days supported by stored harvested water in
tank to consumer………………………………………………………… 51

CHAPTER – 9 Conclusion …………………………………………………………51

Page 4

List of Figures Page No.
Fig. 1. Components of Rainwater Harvesting system …………………………….. 8
Fig. 2. About 450 million people in 31 countries (shaded) face a
serious water shortage ……………………………………………………… 12
Fig. 3 About 2.8 billion people in 48 countries (shaded), including India,
are expected to face water shortages ……………………………………….. 12
Fig. 4. Satellite View of lodra school …………………………………. 18
Fig. 5. Complete Dimensions of Roof Top of classroom Bulding ………………….. 27

Fig. 6. Showing Amount of Rainfall collected in Various Months ……………….. 29

Fig..7 Showing Volume of water Collected from Rainfall monthly ………………. 29

Fig. 8. Ball Valve Type First-Flush Mechanism……………………………………….44

Fig. 9. Simple cloth filter………………………………………………………………..45

List of Tables

Table. 1. Monthly rainfall data of lodra school……………………………….. 19
Table. 2. Calculation of rooftop area of all building …………………………………. 20

Table. 3. Value of runoff coefficient (k) …………………………………………… . 23

Table. 4. Rainfall & Discharge collected throughout the year for

School Building ……………………………………………………. 28

Table.5. Detail Estimation of Sump ……………………………………………………42

Table 6. Abstract of estimation cost ………………………………………..…………..43

Table. 7. Rooftop area & runoff of all building…………………………………………48

Table 8. Monthly hydrological analysis of all building………………………………..49

Table 9. Dimension of tank & its cost……………………………………………….. ..50

Table 10. Distribution of Stored Water……………………………………………….. .52

Page 5

CHAPTER – 1

INTRODUCTION

1.1 INTRODUCTION
1.1.1 Features of Rainwater Harvesting
1.2 COMPONENTS OF RAINWATER HARVESTING SYSTEM
1.2.1. Catchments
1.2.2. Coarse Mesh
1.2.3. Gutters
1.2.4. Conduits
1.2.5. First-flushing
1.2.6. Filters
1.2.7. Storage Facility
1.2.8. Recharge Structure
1.3. Studies Carried out Globally
1.4. Studies carried out in India

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1.1 INTRODUCTION

Rainwater harvesting is the simple technique to collect the water from fall
and store in Tanks for use to recharge ground water depending upon situation. Rainwater
harvesting is a technology used to collect, convey and store rain water for later use from
relatively clean surfaces such as a roof, land surface or rock catchment. It is depend upon the
rain fall during the season. Rainwater harvesting is one of the alternative technology for
delivering drinking water.

Water conservation has become the need of the day. Rainwater harvesting is
a way to capture the rainwater at the time of downpour, store that water above the ground or
charge the underground water and use it later. This happens in open areas as well as in
congested cities through the installation of required equipment. The collection and storage of
rainwater from run-off areas such as roofs and other surfaces has been practiced since ancient
times in India. It is particularly useful where water supply is inadequate.

The reality of water crisis cannot be ignored. India has been notorious of
being poor in its management of water resources. The demand for water is already
outstripping the supply. Majority of the population in the cities today are groundwater
dependent. In spite of the municipal water supply, it is not surprising to find people using
private tube wells to supplement their daily water needs. As a result, the groundwater table is
falling at an alarming rate.

1.1.1 Features of Rainwater Harvesting are:

? Reduces urban flooding.
? Ease in constructing system in less time.
? Economically cheaper in construction compared to other sources, i.e. dams, diversion,
etc.
? Rainwater harvesting is the ideal situation for those areas where there is inadequate
groundwater supply or surface resources.

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? Helps in utilizing the primary source of water and prevent the runoff from going into
sewer or storm drains, thereby reducing the load on treatment plants.
? Recharging water into the aquifers which help in improving the quality of
existing groundwater through dilution

1.2 COMPONENTS OF RAINWATER HARVESTING SYSTEM :

A rainwater harvesting system comprises of components for – transporting
rainwater through pipes or drains, filtration, and tanks for storage of harvested water. The
common components of a rainwater harvesting system are:-

1.2.1 Catchments:

The surface which directly receives
the rainfall and provides water to the system is
called catchment area.

It can be a paved area like a terrace
or courtyard of a building, or an unpaved area Figure 1: Components of Rainwater
like a lawn or open ground. A roof made of Harvesting system
reinforced cement concrete (RCC), galvanized
iron or corrugated sheets can also be used for
water harvesting.

1.2.2. Coarse Mesh:

It prevents the passage of debris, provided in the roof.

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1.2.3. Gutters:

Channels which surrounds edge of a sloping roof to collect and transport
rainwater to the storage tank. Gutters can be semi-circular or rectangular and mostly made
locally from plain galvanized iron sheet. Gutters need to be supported so they do not sag or
fall off when loaded with water. The way in which gutters are fixed mainly depends on the
construction of the house, mostly iron or timber brackets are fixed into the walls.

1.2.4. Conduits:

Conduits are pipelines or drains that carry rainwater from the catchment or
rooftop area to the harvesting system. Commonly available conduits are made up of material
like polyvinyl chloride (PVC) or galvanized iron (GI).

1.2.5. First-flushing:

A first flush device is a valve which ensures flushing out of first spell of rain
away from the storage tank that carries a relatively larger amount of pollutants from the air
and catchment surface.

1.2.6. Filters:

The filter is used to remove suspended pollutants from rainwater collected from
rooftop water. The Various types of filters generally used for commercial purpose are
Charcoal water filter, Sand filters, Horizontal roughing filter and slow sand filter.
1.2.7. Storage facility:

There are various options available for the construction of these tanks with
respect to the shape, size, material of construction and the position of tank and they are:-

Page 9

Shape: Cylindrical, square and rectangular.

Material of construction: Reinforced cement concrete(RCC), masonry, Ferrocement etc.

Position of tank: Depending on land space availability these tanks could be constructed
above ground, partly underground or fully underground. Some maintenance measures like
disinfection and cleaning are required to ensure the quality of water stored in the container.

If harvested water is decided to recharge the underground aquifer/reservoir,
then some of the structures mentioned below are used.

1.2.8. Recharge structures:

Rainwater Harvested can also be used for charging the groundwater aquifers
through suitable structures like dugwells, borewells, recharge trenches and recharge pits.
Various recharge structures are possible – some which promote the percolation of water
through soil strata at shallower depth (e.g., recharge trenches, permeable pavements) whereas
others conduct water to greater depths from where it joins the groundwater (e.g. recharge
wells). At many locations, existing structures like wells, pits and tanks can be modified as
recharge structures, eliminating the need to construct any fresh structures. Some of the few
commonly used recharging methods are recharging of dug wells and abandoned tube wells,
Settlement tank, Recharging of service tube wells, Recharge pits, Soak ways /Percolation pit ,
Recharge troughs, Recharge trenches, Modified injection well.

.
1.3. STUDIES CARRIED OUT GLOBALLY

Today due to rising population & economical growth rate, demands for
the surface water is increasing exponentially. Rainwater harvesting is seems to be a perfect
replacement for surface & ground water as later is concerned with the rising cost as well as
ecological problems. Thus, rainwater harvesting is a cost effective and relativelyPagelesser10

complex way of managing our limited resources ensuring sustained long-term supply of
water to the community. In order to fight with the water scarcity, many countries started
harvesting rain. Major players are Germany (Biggest harvesting system in Germany is at
Frankfurt Airport, collecting water from roofs of the new terminal which has an large
catchment area of 26,800 m2), Singapore (as average annual rainfall of Singapore is 2400
mm, which is very high and best suited for rainwater harvesting application), Tokyo (as
RWH system reserves water which can be utilized for emergency water demands for seismic
disaster), etc.

1.4. STUDIES CARRIED OUT IN INDIA
Today, only 2.5 per cent of the entire world’s water is fresh, which is fit for
human consumption, agriculture and industry. In several parts of the world, however, water is
being used at a much faster rate than can be refilled by rainfall. In 2025, the per capita water
availability in India will be reduced to 1500 cubic meters from 5000 in 1950. The United
Nations warns that this shortage of freshwater could be the most serious obstacle to
producing enough food for a growing world population, reducing poverty and protecting the
environment. Hence the water scarcity is going to be a critical problem if it is not treated now
in its peanut stage. Contrasting figures of water scarcity in world between two timeline (1999
; 2025) are shown in the fig. 2 ; fig 3.

Some of the major city where rainwater harvesting has already implemented is Delhi (Centre
for Science and Environment’s (CSE) designs sixteen model projects in Delhi to setup
rainwater harvesting structures in different colonies and institutions), Bangalore (Rainwater
harvesting at Escorts-Mahle-Goetze, Designed by S Vishwanath, Rainwater club,
http://www.rainwaterharvesting.org/People/innovators-urban.htm#svis ), Indore (Indore
Municipal Corporation (IMC) has announced a rebate of 6 per cent on property tax for those
who have implemented the rainwater harvesting work in their house/bungalow/building). Page 11

Figure 2: About 450 million people in 31 countries (shaded) face a serious water shortage

Figure 3: About 2.8 billion people in 48 countries (shaded), including India, are expected to
face water shortages

Page 12

CHAPTER – 2

LITERATURE REVIEW

This chapter reviews the literature relevant to the objective of the study, i.e., Rainwater
harvesting system in the lodra school as well as the information on development of its
components. A brief review on complete analysis & designing of the different component of
this system has also been included. A discussion on the purpose of rainwater harvesting i.e.
storing harvested water in tank after different available way of filtration and different
component & ways of recharging underground aquifer for increasing the water table level
and increasing soil moisture condition for good agriculture purpose has also been
incorporated. Again, on recharging underground aquifer, underground water can be fetched
out by pumping .

Rainwater harvesting is an yearlong ancient technique studied by many scientist for different
purposes e.g. for storing the harvested water in some storage tank, impact of rainwater
harvesting on social and economic aspects and for recharging underground aquifer for
increasing soil moisture condition. A few of them has been listed.

Rural Rainwater Harvesting: Concept, Techniques, and Social & Economical Impacts by Dr.
Osman Mohammed Naggar. This person has really dedicated his work in finding out all the
factors which affects the surface runoff and rainwater harvesting impacts on environment.

Again a very decant work is being done by P.Sai Rukesh Reddy and A.K.Rastogi? in their
paper entitled, „Rainwater Harvesting in hostel 12 and hostel 13 of IIT Bombay , The Indians
society for Hydraulics and Journal of Hydraulic Engineering(2008). In this paper, rainwater
is being conserved/harvested only for two hostel areas. And they used two methods of
distribution of harvested rainwater (Rapid depletion method & Rationing method). Finally,
the cost for construction of tank was calculated.

Page 13

Apart from it, two books entitled 1. Estimation and costing in civil engineering, by :- Dutta,
B. N. 2. R.C.C. Designs, By:- Punmia B.C., Jain Ashok, & Jain Arun Kumar , was referred.
These books has carried out complete costing and estimation of sump and complete structural
analysis of underground sump. So these two paper was being referred while doing complete
structural analysis and calculating the complete cost of construction of tank.

Reference Websites used by us
www.rainwaterharvesting.org
www.imdahm.gov.in

Page 14

CHAPTER – 3

OBJECTIVE OF RAINWATAR HARVESTING AT
LODRA SCHOOL

The campus of this institute is situated at the Western end of the city and opposite of the
lodra , over an area of 67000 m² (16.55 acres) of land provided for This Campus. There are
Five departments , one workshop and one halls in the sth c.u. vidyalaya lodra. Hence, total
strength of campus including students and staffs people will be more than 2,000. And its still
under the expansion project adding more number of students and faculty person and
increasing facilities by involving lots of new departmental building and infrastructures.

Thus, with this present strength and also with the expansion programmes, campus should also
increase its facilities and maintenance requirements. Thus water is the most natural resource
which is being always in high demands by human being and is indispensable part of the life.
If this demand is not met, then its will lead to water scarcity. Now on days, water scarcity has
become the most common problem in every parts of India. And, this problem is also being
profoundly seen in the residences halls inside the campus. And, if its has not been dealt
earlier with proper care then this problem will become a major hurdle in the development
phase of campus and the standard of living of will declining.

Hence, keeping in view all the above problems and status of campus, the administrative body
should focus more on the water scarcity problem. Therefore, in this situation, Rainwater
harvesting system can be considered as a best solution for fighting against scarcity of water
inside campus.
Moreover, owing to its simple technique, ease of construction & installation and low cost of
investment, this technique again suites for implementation inside lodra school . Rainwater
harvesting can meet potable and non-potable water demands and also control flooding.
Again, this non-potable harvested rainwater can be best utilized for purpose of constructing
new infrastructure building, gardening, etc. which reduces the investment to be made for
filtration purpose. And in this way, campus can easily meet the potable water demand and
also able to save money which is being spends for procuring potable-water Page. 15In

this way potable water can be conserve and harvested rainwater plays major part in
conserving it. Rainwater harvesting also helps in increasing the soil moisture condition and
fertility factor of soil for plantation. Hence, this simple technique tends to increase the
greenery surrounding the campus, increasing aesthetic factor for a proper residential institute
to live in. Thus in that similar way, rainwater harvesting systems has endless advantages
without any harmful disadvantages or if there are any, then it must be negligible.

Hence for water scarcity, Rainwater harvesting is seems to be a perfect replacement for surface &
ground water as later is concerned with the rising cost as well as with ecological problems.
Therefore, Rainwater harvesting is highly recommended for lodra Campus.

Page 16

CHAPTER – 4

STUDY AREAS

&

DATA COLLECTION

4.0. STUDY AREAS AND DATA COLLECTION
4.1. STUDY AREAS
4.2.1. Rainfall Data Collection
4.2.2. Calculation of catchment area

4.0. STUDY AREAS AND DATA COLLECTION

4.1. STUDY AREAS

As discussed earlier in the section of introduction – importance of rainwater harvesting at
lodra primary school, we clearly came to know the all the advantages which we can draw out
by implementing this small but highly efficient technique in the school. Thus to increase the
potential, benefits of this system and draw maximum advantages from it, we need to have
large rooftop areas which will be going to act as catchment areas. More the catchment areas
more will be the surface runoff and thus more will be the amount of harvested water.

Page 17

Therefore as much as possible, we have included and considered all the major buildings
having large rooftop areas. Hence, study areas includes all the Department Building with the
principal office and all class room, such as , Metallurgical and many others departments,
central library, computer center, and various laboratory). Given below a satellite picture, fig
no.4, showing majority of the buildings considered for rainwater harvesting system at lodra
primary school .

Figure 4:LODRA Google Earth, Date: 2 th 0CT0BER , 2018}

4.2. DATA COLLECTION

4.2.1. RAINFALL DATA COLLECTION
Lodra school is located at 23°46’39.34″N 72°73’28.37″E in a lodra mansa gandhinagar
district of Gujarat at an elevation of about 135.075 meters above mean sea level. The average monthly rainfall data are being taken from the” meteorological web site of Ahmadabad, Gujarat . Again its followed that, lodra is a small city and thus has a uniform average rainfall through out the city in all location.

Page 18

Thus monthly rainfall data of the lodra mansa city is given below in the table no.1 which is
assumed to be same for the station of lodra campus.

TABLE NO.1: MONTHLY RAINFALL DATA OF LODRA SCHOOL CAMPUS
MONTH RAINFALL (mm)
JANUARY 2
FEBRUARY 0
MARCH 2
APRIL 1
MAY 5
JUNE 76
JULY 302
AUGUST 221
SEPTEMBER 183
OCTOBER 14
NOVEMBER 6
DECEMBER 3

TOTA
L 784

4.2.2. DETERMINATION OF CATCHMENT AREA

The rooftop surface area is nothing but the catchment area which receives
rainfall. Catchment areas of the different Institutional departments are?
measured. This measurement was done manually with? the help of „reinforced
fiber tape which is the simplest technique known as „tape survey . Before using
the tape, tape was checked for any zero error and also length of the tape was
also carefully checked for its accuracy. Those places which area? not accessible
to land on, are measured by using the ruler from tool box of „Google Earth .
Given below the
table no. 2 for calculated the rooftop areas of all the buildings suited inside the
campus:-

Page 19

TABLE NO. 2: CALULATION OF ROOFTOP AREA OF ALL BUILDING

Serial no. Building Name Rooftop area (m²)

1 All class room Building 1350

2

Laboratories 930

3 Principal office Building 1426

4 Computer Building 2593

5 librari building 490

7 Hall 362

Page 20

CHAPTER – 5

METHODOLOGY

5.1. HYDROLOGICAL ANALYSIS
5.2. Methods for storage of harvested rainwater in tank
5.2.1. Rationing Method (RM)
5.2.2. Rapid Depletion Method (RDM)
5.3. GIS Analysis

5.1. HYDROLOGICAL ANALYSIS

On the basis of experimental evidence, Mr. H. Darcy, a French scientist enunciated in 1865, a
law governing the rate of flow (i.e. the discharge) through the soils. According to him, this
discharge was directly proportional to head loss (H) and the area of cross-section (A) of the
soil, and inversely proportional to the length of the soil sample (L). In other words,

Q = Runoff

Page 21

Here, H/L represents the head loss or hydraulic gradient (I), K is the co-efficient of
permeability

Hence, finally, Q = K . I . A

Similarly, based on the above principle, water harvesting potential of the catchment area was
calculated.
The total amount of water that is received from rainfall over an area is called the rainwater
legacy of that area. And the amount that can be effectively harvested is called the water
harvesting potential.
The formula for calculation for harvesting potential or volume of water received or runoff
produced or harvesting capacity is given as:-

Harvesting Potential or Volume Of Water Received (m³)
= Area of Catchment (m²) X Amount of Rainfall (mm) X Runoff coefficient

Runoff coefficient for any catchment is the ratio of the volume of water that runs off a
surface to the volume of rainfall that falls on the surface. Runoff coefficient accounts for
losses due to spillage, leakage, infiltration, catchment surface wetting and evaporation, which
will all contribute to reducing the amount of runoff. Runoff coefficient varies from 0.5 to 1.0.
In present problem statement, runoff coefficient is equal to 1 as the rooftop area is totally
impervious. Eco-Climatic condition (i.e. Rainfall quantity & Rainfall pattern) and the
catchment characteristics are considered to be most important factors affecting rainwater
Potential. Given below the table showing the value of runoff coefficient with respect to types
of surface areas:-

Page 22

TABLE NO. 3: VALUE OF RUNOFF COEFFICIENT (K)

Sr Types of area
Value of K Flat land 0-5 % Rolling land Hilly land no. slope 5%-10% 10%-30%
slope Slope
1. Urban areas 0.55 0.65 –
2. Single family 0.3
residence
3. Cultivated Areas 0.5 0.6 0.72

4. Pastures 0.30 0.36 0.42

5. Wooden land or 0.3 0.35 0.50
forested areas

Source : Table 7.31, Chaper Hydrology and runoff computation, Irrigation Engineering &
Hydraulic Structure, by Garg, S.K.

5.2. METHODS FOR STORAGE OF HARVESTED RAINWATER IN
TANK

Finally, we need to store the water which is obtained from the rooftop areas of the different
buildings. The volume of tank which stores the harvested water will be directly proportional
to the total volume of water harvested.
Technically, there are two types of methods for distributing the harvested rainwater:-
• RATIONING METHOD (RM)

• RAPID DEPLETION METHOD (RDM)

To explain these both methods, let us first apply it on any Building say Engineering
Building.. The detail calculation is carried out to get the valuable steps. Later on, these
crucial steps are again applied to all other building and number of days for consumption of
stored water is calculated by using both of these methods.

Page 23

5.2.1. RATIONING METHOD (RM):

The Rationing method (RM) distributes stored rainwater to target public in such a way that
the rainwater tank is able to service water requirement to maximum period of time. This can
be done by limiting the amount of use of water demand per person.
Suppose in this method, the amount of water supplied to student is limited which is equal to
say, 100 lt/day per capita water demand

Again, Number of students at school Building = 300
Then, Total amount of water consumption per day = 300 x 0.1 = 30 m³/day Total
no. of days we can utilize preserved water = stored water / water demand

For school Building, volume of water stored in tank was taken approx. = 3000 m3
Hence finally, no of days = 3000/30 = 100 days ( 3 month 10 days)
For long term storage of preserved water in good condition, preserving chemical should be
added.

5.2.2. RAPID DEPLETION METHOD (RDM):

In Rapid Depletion method, there is no restriction on the use of harvested rainwater by
consumer. Consumer is allowed to use the preserved rain water up to their maximum
requirement, resulting in less number of days of utilization of preserved water. The rainwater
tank in this method is considered to be only source of water for the consumer, and alternate
source of water has to be used till next rains, if it runs dries.

For example if we assume per capita water demand = 120 lt/day = 0.12 m3/day

Total amount of water consumption per day = 300 x 0.12 = 36 m3/day

Total no. of days, preserved water can be utilize = stored water / water
demand = 3000 / 36
= 84 days (2 month 24 days)

Page 24

Hence, finally it is observed that, if the amount of water stored is equal to 3600 m3, then
applying
1. RDM, consumer can only utilize the preserved stored water for about 84 days (2 month 24
days),

2.Where as in RM, preserved stored water can be utilized for a period of 100 days (3 month
10 days).

5.3. GIS ANALYSIS

A geographic information system (GIS) is computer software that allows our young students,
researchers and investigators to manage and manipulate interactions between data and geographic
locations. GIS technology has the sophistication to go beyond mapping as simply a data
management tool. GIS can integrate georeferenced imagery as data layers or themes and link
them
other data sets to produce geospatial representations of data. These geographical pictures not only
depict geographic boundaries but also offer special insight to students and researchers across
disciplines such as health, economics, agriculture, and transportation.

Thus, in the present case, ILWIS 3.0 is being chosen as the software for carrying out the GIS
analysis. Our aim is to convert the scanned map of the NIT Rourkela campus into a digital
elevation model map, which gives detail distinct information on the variation in the elevation of
different regions of surface giving clear idea on the surface topology. The high contour lines on
the digital elevation model denotes surfaces of high altitudes i.e. Mountainous region and low
lining contour lines denotes the surfaces with low altitudes such as valley region.

Page 25

CHAPTER – 6

OPTIMISTIC DETERMINATION OF SIZE
&
TYPES OF TANK

6.1. General
6.2. Computation of Volume of Runoff per year
6.3. Optimum dimension of tank
6.4. Types of tank

6.1. GENERAL

Just to start with, now let us consider only one Engineering Building and proceed with
calculation in details. And all the calculation in the later part of this project will be adopted
for rest of the building. This Building presently has capacity of 500 students including staffs.

The total rooftop area of the Engineering Building available for the rainwater harvesting is
1347 m2. The cumulative runoff that can be captured from the paved area is calculated using
Gujarat Meteorological Department. The cumulative rainfall runoff at the end of the year is
calculated to be 3900m3. The tank capacity can be estimated to be a lower value accounting
for the continuous consumption going on during period of rainfall.

Page 26

6.2. COMPUTATION OF VOLUME OF RUNOFF PER YEAR:

As we know the formula for runoff discharge from section 5.1. is

Volume of water Received (m3) = Area of Catchment X Amount of Rainfall

Total roof area of school Building was calculated = 1350 m2 Average
annual rainfall at Himatnagar = 784 mm/year = 0.784 m /year

Total volume of surface runoff water suppose to be collected= 1350 x 0.784 = 1058.4
m³/year.
Lodra school building

Lodra school
building 145ft

100 ft

Fig. 5 : Complete Dimensions of Roof Top of school Building

Page 27

Given below the table no 4 which gives the monthly rainfall and discharge runoff obtained
from the rooftop area of school Building and corresponding graph are also plotted in the fig.5
and fig.6.

Table No.4: Showing Rainfall & Discharge of school Building monthly at lodra school

Sr. No Month Rainfall(mm) Volume (m3)
1 January 2 2.7
2 February 0 0
3 March 2 2.7
4 April 1 1.35
5 May 5 6.75
6 June 76 102.6
7 July 302 407.7
8 August 221 298.35
9 September 183 274.05
10 October 14 18.9
11 November 6 8.1
12 December 3 4.05
TOTAL 784 1127.25

Page 28

Rainfall (mm)

900
800
700
600
500
400 Rainfall (mm)
300
200
100
0

Fig.6 : Showing Amount of Rainfall collected in throughout the year

Volume (m³)
1200

1000

800

600

400 Volume (m³)

200

0

Fig.7 : Showing Volume of water Collected from Rainfall throughout the year

Page 29

6.3. OPTIMUM DIMENSION OF THE TANK

A flat roof has a runoff coefficient of 0.7, which means that 70% of the rain can be harvested.
Based on this runoff coefficient and a roof area of 1350 m²

square metres a volume of 283.5 litres of water can be collected in the driest month
(February) and 285390 litres in the wettest month (July).

The total yearly amount of water that can be collected from the roof is 740880 litres in an
average year.

The water demand is 3600 litres per day, which equals to about 108000 litres per month. The
total water demand is 1314000 litres per year.

The amount of water that can be collected from the roof is less than the water demand . Only
a part of the water demand can be fulfilled using a rainwater harvesting system..

Required storage

The total amount of water that can be collected from this roof, 740880 litres, is not enough to
fulfill the total yearly water demand 1314000 litres.

However, it might still be worthwhile to construct a rainwater harvesting system. With a
storage reservoir of 463500 litres (463.5 m³) a rainwater

harvesting system could provide 2030 litres of water per day, which is 20% of the total
demand.

The storage reservoir will be full in and then slowly drain until it is (almost) empty at the end
of May.

Dry and wet years

This calculation is based on the average monthly rainfall. The actual rainfall differs from
month to month and year to year. The amount of available

water and filling of the tank might therefore be different and change from year to year.

Page 30

When constructing a rainwater harvesting system it is important to take this into account.
Below is a description of the situation in a dry year (20%

chance) and a wet year (20% chance).

Situation in a dry year: during a dry year, there is less rain to fill the system. The system can
provide a smaller amount of water compared to an

average year. All rain is stored, so constructing a larger reservoir won’t help.

Situation in a wet year: during a wet year there is more water available and constructing a
larger tank will increase the water availability in this

situation. With a storage reservoir of 686600 litres a rainwater harvesting system could
provide 30% of the total demand.

6.4. TYPES OF TANK:

Two type of tank can be used for storing of rainwater discharged from the roof LINED
STORAGE TANK UNLINED NATURAL STORAGE TANK

In lined storage tank, earth work excavation is done and under ground RCC water storage
tank is constructed which is completely covered from the top. The land above the tank can be
used for serving as playground or parking slot, etc. In unlined natural storage tank, earth
excavation is done and all the water being allowed to fall directly in that pit and store it. In
this method, we get two advantages.

Firstly, our natural water gets recharged leads to augmentation of water level and ground
condition, increasing prospects for better future cultivation and plantation. Secondly,
underground water can be extracted any where within some limited areas from that pit and
can be used to satisfy daily water demand.

Page 31

CHAPTER – 7

DETAIL ANALYSIS

&

DESIGNING OF RAINWATER HARVESTING

SYSTEM COMPONENT

ON ONE SAMPLE BUILDING

7.1 Analysis & Design Of underground Sump

7.2. Detail cost estimation of sump (underground tank)
7.3. Gutter design
7.4. First flush mechanisms
7.5. Filtration

In this section, all the component of rainwater harvesting system is to be designed for all the
buildings located inside the lodra school Campus.

Hence to start of, a sample calculation was done on Engineering Building, which will draw
the steps which has to be followed by all other building for designing its system components.

Hence given below the complete design of all the components of rainwater harvesting of
Engineering Building whose dimensions are mentioned in the figures 7 and tank size is 4
X 5 X 12.

Page 32

7.1 ANALYSIS & DESIGN OF UNDERGROUND SUMP

Problem Statement :

Height of tank= 4m
Area of base = 60m2
Taking subsoil consists of sand, angle of repose = 30®
Saturated unit weight of soil = 17 K/m3
Water table likely to rise up to ground level
M20 concrete, HYSD bar
Unit weight of water = 9.81 KN/m3

Solution:

There are four components of design:-
i) Design of long wall
ii)Design of short wall
iii)Design of roof slab
iv)Design of base slab

1. GERNERAL

Design of wall be done under two condition:-

a) Tank full with water, with no earth fill outside

b) Tank empty with water, with full earth pressure due to saturated earth fill.

The base slab will be design for uplift pressure and the whole tank is to be tested
against floatation.

Taking size of the base of tank =12X5m
As length (L)=12m
Page 33

Breadth(B)=5m
L/B=12/5=2.3{>2} , Hence long wall be designed as a cantilever.
Bottom H/4 =4/4 = 1m of short wall be designed as cantilever , while
Top portion will be design as slab supported by long walls.

2. DESIGN CONSTANT

For M20 concrete, ?cbc=7N/mm2 , m=13
Since face of wall will be in contact with water for each
condition, ?st=15N/mm2 for HYSD bar.
Permissible compressive stress is steel under direct compression = ?sc = 175
N/mm2 For ?cbc = 7 N/mm2 , ?st = 150 N/mm2 , m= 13 ,
We have, K = = 0.378
J= 1-(0.378/3) = 0.874
R = 1/2 X 7 X 0.874 X0.378 = 1156

3. DESIGN OF LONG WALL
a) Tank Empty with pressure of saturated soil from outside
Pa = Ka?H+?wH

? = =1/3

??=17-981=7.19 Kn/m3 = 7190 n/m3
?w = 9.81 Kn/m3
Pa = (1/3)X7190X4 + 9810X4 = 48,426.67 N/m2
Maxm. B.M. @ base of wall = 48,426.67 X (4/2)X (4/3) = 130,204.44 nm

D= =335.6mm

Provide total depth D= 380 mm
D = 380 -35 = 345 mm
Ast = = 2,878.75 mm2
Page 34

Using 30mm ? bar, spacing = =109.13mm
Hence, provide 20mm ? bar @ 100mm c/c on the outside face @ bottom of long wall.

CURTAILMENT OF REINFORCEMENT

Since the B.M. is proportional to h3
Asth/Ast = (h/H) 3 from which, h= H(Asth/Ast)
^(1/3) If Asth = 1/2XAst (I.e. half of bar being
curtailed) h= H(1/2)^(1/3) = 4(1/2)^(1/3)=3.17 m
Height from base = 4-3.17 = 820 mm
Height as per code, IS 456, bar should contain further for a distance of 12? or d (which ever
more)
12 X? = 12X 12 = 240
D=345mm,
So bar curtailed @ distance from the base = 820+345 = 1.17m
Min % of reinforcement = 0.3 – 0.1 ( ) = 0.23
% Min Ast = 0.23X380X1000/100=879.43mm2
So, curtailment @ 1.17m from the base = 0.5XAst = 0.5 X 28787 =1439.35 > 879.43 (O.K)

DISTRIBUTION REINFORCEMENT

Ast = 879.43 mm2
Area to be provided on each face = 879.43/2 = 439.72 mm2
Hence proving 10mm ? @ spacing = 170mm
Taking spacing = 160mm on both face of long wall

DIRECT COMPRESSION IN LONG WALL

The earth pressure acting on short wall will cause compression in long wall, because
top portion of short wall act as slab support on long walls. At h=1m(>H/4) above the
base of short wall Page 35

Pa=Ka??(H-h)+? w (H-h)
=(1/3)X7190(4-1)+9810(4-1) = 33,620N/m2
This direct compression developed on long wall is given by
Plc=Pa.B/2=33620X5/2 = 91,550 N {This will be taken by distribution steel & wall section.}

B>TANK FULL WIT H WATER & NO EARTH FILL OUTSIDE

P=?wh=9810×4
=39240 N/M2
M=P.H2/6 = 39,240 X42/6 = 104640 Nm
Ast = = 2,313.53 mm2

Using 20mm ? @ spacing = = 135.7
Taking 20mm ? @ spacing 130mm c/c @ inside face.

CURTAILMENT OF REINFORCEMENT

Asth/Ast = (h/H) 3 from which, h= H(Asth/Ast) ^(1/3)
If Asth = 1/2XAst (I.e. half of bar being curtailed)
h= H(1/2)^(1/3) = 4(1/2)^(1/3)=3.17 m
Height from base = 4-3.17 = 820 mm
Height as per code, IS 456, bar should contain further for a distance of 12? or d (which ever
more)
12 X? = 12X 12 = 240
D=345mm,
So bar curtailed @ distance from the base = 820+345 = 1.17m
So, at the base, 20 mm ? @ 130mm c/c
At top from 1.17m from base, 20mm ? @ 260mm c/c

DIRECT TENSION ON LONG WALL:-

Page 36

Since the top portion of short wall act as slab supported on long wall, the water pressure
acting on short wall will cause tension in long wall:-Pl=P.B/2 = 9810 X 3X 5/2 = 73,
575 N
As req. = 73,575/150 = 490.5mm2
Area of distribution steel (=879.43 mm2) will take direct tension.

4.DESGIN OF SHORT WALLS

A) TANK EMPTY WITH EARTH PRESSURE FRON OUTSIDE

I) TOP PORTION
The bottom 1m (H/4) act as cantilever while the remaining above 3m act as slab on long wall
At, =1m, above base of short wall,
Pa-= Ka??(H-h)+? w (H-h)

=(1/3)X 7190X3 + 9810 X 3 = 36,620 N/m2
[email protected] support = PaL^2/12 = 36,620 X 5^2 / 12 = 76,291.67 Nm
This causes tension outside.
Mf @ centre = PaL2/8 – Mf = 36,620 X 52 (1/8- 1/12) = 38,145.83 Nm
d= 380 –(25+20+10) = 325 mm
At support, Ast = = 1790.57mm2

Using 16mm ? bar Ast = = 116.7mm
So providing 16mm ? [email protected] spacing 110mm c/c @ outer face.
At mid span, Ast = (0.5X1790.57 = 895.285 mm2
Providing 16mm ? @ spacing = 223.3 .i.e. providing 220mm c/c at inner face

II)BOTTOM PORTION

The bottom 1m will bend as cantilever.
Intensity of earth pressure @ bottom = 48,826.67 N/m2 (from step 3)
M = 0.5X 48,826.67X1X (1/3) = 8137.78 Nm
Ast = = 179.92 mm2

Page 37

Minm. Steel @ 0.23% = 879.43 mm2
So, Ast = Ast minm.
Spacing of 12mm ? = = 128.5 .i.e. 120 mm c/c
Hence providing 12mm ? bar @ spacing 120mm c/c at the outside face in vertical direction
for bottom 1m height.

DIRECT COMPRESSION IN SHORT WALL

Only one meter of long pushes the short wall due to earth pressure, Pbc = PaX1
=36,620n This compression is being taken up by distribution reinforcement.

B)TANK FULL WITH WATER AND NO EARTH FILL OUTSIDE

i)TOP PORTION
P=W(H-h) = 9810 X3 = 29,430 N/m2
Mf @ support = PB2/12 = 29430 X 5^2 / 12 = 61,312.25 Nm causing tension at the inside.

Mc @ centre = PB2/24 = 0.5 X 61,312.5 = 30,656.25 Nm causing tension at the outside.
Direct tension on short wall due to water pressure on the end 1meter of long wall
P b =W(H-h) X 1
=29,430 X1 = 29430 N
Effective depth d, for horizontal steel= 325mm @ distance x = d-D/2 = 325 – 380/2
= 135 mm
Ast1 = M-Pbx/?stjd
Ast2 = Pb/?s

AT INSIDE FACE (END OF SHORT WALL)

Ast1 = = 1345.8mm2
Ast2 = 29430 / 150 = 196.2 mm
Page 38

Total = 196.2+1345.8 = 1542 mm2
Using 12mm ? bar, spacing = 1000X113/1542 = 75 mm c/c.

AT OUTSIDE FACE (MIDDLE OF SHORT WALL)

Ast1 = = 636.26mm2
Ast2 = 29430 / 150 = 196.2 mm
Total = 196.2+636.26= 822.46 mm2
Using 12mm ? bar, spacing = 1000X113/822.46 = 120 mm c/c @ outside face.
i)BOTTOM FACE

P (from step 3b)= 39240 N/m2
Mf 0.5X(1/3)X 39240 = 6540 Nm causing tension at the inside.
Mc @ centre = PB2/24 = 0.5 X 61,312.5 = 30,656.25 Nm causing tension at the outside.
Ast = = 144.6 mm 2
But min. Steel req. = 879 mm2
So providing 12mm ? bar @ spacing 120mm c/c.

SUMMARY OF REINFORCEMENT IN SHORT WALL

Taking of maxm out of both case 4A and 4B

I) Horizontal reinforcement @ inner face = 16mm ? @ 75mm c/c
I) Horizontal reinforcement @ outer face = 16mm ? @ 110mm c/c
III) Vertical reinforcement @ inner face & outer face = 12mm ? @ 120mm c/c

5.DESIGN OF TOP SLAB

L/B = (12/5 ) = 2.4 (> 2) i.e. one way slab
Let live load on top slab = 2000 N/m2
Assuming thickness of 200mm including finishing ,etc. Page 39

Self weight = 0.2 X 1X1X 25,000 = 5000 N/m 2
Total weight = 2000+5000 = 70000 N/m2
M = WB^2 / 8 = 7000(5+0.38) 2 / 8 = 25,326.35 Nm
D= = 140mm
Providing a total thickness (D) = 180mm
d = 180-25-6 = 149 mm

Ast = = 1302.5 mm2
Spacing of 16mm ? = 1000X201/1302.5 = 150 mm c/c @ outside face.

DISTRIBUTION REINFORCEMENT

Pt % = 0.3 – 0.1 X = 0.277%
Spacing of 10mm ? bar = 1000 X 78.54 / 415.7 = 180 mm c/c

6.DESIGN OF BOTTOM SLAB
Magnitude of uplift pressure, Pu = WH1= 9810 X 4.3 = 42,183 N/m2

A) CHECK FOR FLOATION
Check is done when tank is empty.
Total upward floatation force = P = Pu X B X L = 42183X5X12 = 2530980 N
Total Downward force = weight of wall + (weight of roof slab + finishes) + weight of base
slab
= 0.38(5+5+12+12) X4.3X25000 + 0.2X 5X12X25000 + 5X12X0.3X25000
= 2138900N

Weight of roof so downward force is less than buoyant force, we need to provide extension of
0.5 m on both side.
Extra weight req. = 2530980-2138900 = 392080N
By extending 0.5 on both side, extra weight of tank
= (0.5 x 5 X 2) + (0.5 X 12 X 2) + (0.5 X 0.5 X 4) X 25000 X 0.3= 135000 N
Page 40

Weight of soil = (0.5 x 5 X 2) + (0.5 X 12 X 2) + (0.5 X 0.5 X 4) X 17000 X 4= 1224000 N
Total = 1359000N (safe)

B)DESIGN OF BASE SLAB

Considering 1m length of slab, upward water pressure = 42183N/m2
Self weight of slab = 1 X 1 X 0.3 X 25000 = 7500 N/m2
Net upward pressure, P = 34683 N/m2
Weight of roof slab per meter run = 0.2 (2+0.38)X1X25000 = 11900 N
Weight of wall / meter run = 0.38X4X1X25000 = 38000 N
Weight of earth projection = 1700 X 4 X 1 X 0.5 = 34000 N/m
Net unbalance force / meter run = 34683 (6.286 X 1) – 2 (38000 +11900 + 34000) =
50217.3N
Reaction on each wall = 50217.3/2 = 25108.67 N
Pa = Ka??H + wH = 48826.67 N/m2
Pa =48826.67 X(4/2) X 1 = 97653.34 Nm acting @ (4/3)+0.3 = 1.66 m from the bottom of
base
slab
B.M. @ edge of cantilever portion = (34683 X 0.5 2 / 2 )+ 25108.67 X1.66-
(1700X4X0.52/2)
= 45165.76Nm causing tension @ bottom face.
B.M @ centre of span = ((34683/2)X (6.286) 2/4) + 97653.34X1.66 –
(38000+11900+25108.67)X4.38/2 -1700X4X0.5(6.38/2-0.25) = 234044.7 Nm

d = = 450 mm, so keeping D = 500 mm , d = 450 mm
Ast = = 7140.1 mm2
Providing 24mm ? bar spacing = 1000X 452.4 / 7140 = 65 mm c/c

Distribution reinforcement in longitudinal direction = 0.3 – 0.1
steel = 0.243 X 1000X300/100 = 729 mm2
Area on steel on each face = 729 /2 = 364.5 mm2
Spacing of 8mm ? bar = 1000X 50.3 / 364.5 = 138 mm
Provide 8 mm ? bar @ 130 mm c/c on each face.

= 0.243 % Area o n

Page 41

7.2. DETAIL COST ESTIMATION OF SUMP (UNDERGROUND TANK)

Finally cost of entire project play a crucial role in any type of project. Before implementing
the project, it is highly necessary for the engineers to check project, whether it is economical
or not. Hence, the detail cost estimation should be done.
Tank shall be of first class brickwork in 1:4 cement mortar foundations and floor shall be of
1:3:6 cement concrete. Inside of septic tank shall be finished with 12mm cement plaster and
floor shall be finished with 20mm cement plaster with 1:3 mortar mixed with standard water
proofing compound. Upper and lower portion of soak-pit shall be of second class brickwork
in 1:6 cement mortars and middle portion shall be of dry brickwork. Wall thickness is about
30cm. Roof covering slabs shall be precast R.C.C. The length of the connecting pipe from
latrine seat may be taken as 3 meters. And suitable rates are assumed.
Given below the detail cost estimation of constructing an underground sump of dimensions (4
x 5 x 12) at building site:
Table No. 5: DETAIL ESTIMATION OF SUMP

Sl no Particular No. Length(m) Breadth(m) Height/depth(m) Quantity(m3)
1 earth work in 1 12.80 5.80 4.3 319.232
excavation

2 Cement concrete 1 12.80 5.80 0.3 22.27
1:3:6 in
foundation

3 I class brick work
in 1:4 cement
mortar
i. Long wall 2 12.60 0.30 4 30.24
II.short wall 2 5.0 0.30 4 12
Total 42.24

4 R.C.C work for 1 12.60 5.60 0.20 14.112
slab cover

5 12mm plastering
inside with 1:2
cement mortar
i.long wall 2 12 – 4 96
ii.short wall 2 5 – 4 40
Total 136

Page 42

Table No. 6: ABSTRACT OF ESTIMATION COST
Sl Particular Quantity Rate Cost (Rs.)
no.
1 Earthwork in excavation 319.232 m3 100 Rs/m3 31923.2
2 Cement concrete 1:3:6 in 22.27 m3 2700 Rs/m3 60129
foundation with brick ballast
3 I class brickwork 1:3 cement 42.24 m3 3000 Rs/m3 126720
mortar
4 R.C.C work for slab cover 14.112 m3 2700 Rs/m3 38102.4
5 12mm plastering with 1:2 cement 136 m3 2700 Rs/m3 367200
mortar
Total 624074.6
6 Contingency + work charges (3% + 2 % = 5 %) – 31203.73
establishment
7 Engineering profit 10% – 62407.46
Grand Total 717685.80
Hence, after studying the present market value of material required for constructing the entire
tank and using it while calculating during costing and estimation of tank. After all several
steps, the total cost of tank was came out to be Rs. 7,17,685.80. This steps was applied to all
other building for determining the final cost price of the tank.

7.3. GUTTER DESIGN
A channel which surrounds edge of a sloping roof to collect and transport rainwater to the
storage tank is called gutter. Gutters can be semi-circular or rectangular and generally of PVC
or galvanized iron sheet type of material.

The efficiency of gutter is highly influenced by its choice of optimal size, width and position
relative to the roof edge and its slope. Hence, this parameter is cautiously chosen. So, in order
to collect maximum water, it is highly required to build the gutter with large dimensions.
However, it is economical to make large gutter with reasonable dimension because the value
of water collected from it is much higher than the cost of constructing the gutter. Considering
the throw wind and pulsating effects, gutter width was frozen on the basis of the roof size and
the ideal positioning was found out. Keeping the present case in mind, results of various
studies were extensively analyzed, and a suitable gutter design was proposed.

The final design recommendation is as follows. Design is made for trapezoidal shaped gutter
whose angle was 30º, and its sides are the same length as its base. The gutter has a slope of Page
43

0.5% in the first 2.3rd portion of its length, and 1.0% slope in the last 1.3rd. The gutter width
is designed to be 160mm, of which 120mm is extending out from the roof edge and 40mm
extending towards the inner side.

7.4. FIRST FLUSH MECHANISMS

Fig. 8 Ball Valve Type First-Flush Mechanism

First flush mechanism is shown in the fig.. Due to long dry period, the catchment area
generally gets dirty. Hence in order to prevent entry of excess dirt from the catchment area
from entry into tank and polluting the water, first flush mechanism is designed. And the order
of this mechanism becomes highly important when water preserved is utilized for drinking
purpose. Turbidity factor was also considered while design first flush mechanism. After
studying our requirement and prevailing condition, the design value of this mechanism was
fixed to be 8litres/10m2. And finally Ball-Valve design was chosen. Ball-Valve design has a
unique mechanism for controlling the flow of water into and outside of the tank. Ball-Valve
design is shown in the figure. This system consists of ball inside the specially designed pipe
which opens and closes the opening of outlet to the storage tank and diversion chamber
according the level of water. When the water fills up to the brim, the water is diverted to the
main tank from the side outlet. And when the water needs to be rejected is sent to the small Page
44

diversion chamber where it fills the inlet pipe. Hence total volume of the diversion chamber
and the pipe up to the Ball-Valve are carefully designed to match the diversion volume that is
calculated. The connection between the terrace water and storage tank rebuilds when water
reaches the level of the ball making the ball to float and block the connection between the
terrace water and diversion chamber, thus sending the water back again to main storage tank.
In this way, Small diversion chambers are designed for the downpipes from each terrace. The
diversion tank can have a tap which may be operated.

7.5. FILTRATION

Fig. 9 Simple cloth filter

Filtration is highly required for the rainwater which is harvested from the rooftop area. When
water is use for drinking purpose then this process become even more important. But, basic
filtration is preferable required to avoid excessive dirt entering the system. A very simple,
cost-effective mechanism has been chosen preferred over elaborate commercial systems. Leaf
and twig screen, for basic which is a 5mm thick mesh with wire frame running along the
gutters was selected. With most of the commercial fine filtration systems, there is a general
difficulty of handling high flow rates, thus, a practical filtration method was selected running
the flow through a fine cloth/mosquito net mesh. The flow rate would not be impeded much;
it?s very cost effective and can be easily maintained and replaced. Again, two cloth filters for
hydraulic and cleaning efficiency using a graded sand load can be chosen whose results are
highly comparable to commercial filters. Based on their results, the muslin type of cloth filter
with conical shape was selected for usage in the proposed rainwater harvesting system. The
proposed cloth filter design arrangement is shown in the Figure.

Page 45

CHAPTER – 8

RESULTS
_________________________________________________

8.1. Optimum location of tank /underground reservoir recharging point
8.2. Rainwater harvesting potential of different building at
lodra school

8.3. Detail monthly hydrological analysis of all building
8.4. Dimensions of tank & cost of construction
8.5. Calculation of number of days supported by stored harvested water in
tank to consumer.

8.1. OPTIMUM LOCATION OF TANK / UNDERGROUND
RESERVOIR

RECHARGING POINT

In this section, we need to find out the optimum or best location for underground tank or
recharging point if harvested water decided to recharge the underground reservoir. Earlier we
have already analyzed the entire campus on the platform of hydrology and GIS. And a very
careful study was done on the output results from these analysis steps.

From the figure no 6, the final digital elevation model map, it was found that the surface with
high elevation was situated in the extreme left hand side of the campus. During the rainy season,
all the surface runoff will naturally roll down due to its slope variation and gravitation force. to be
the best location for placing the artificial tank for storage or the artificial recharging point
recharging the underground reservoir. The methods for rechargingPage46

the underground reservoir have already been in dealt in detail in section 1.2.8 of Introduction
part.

from this it is concluded that runoff rainwater will persist in these areas naturally for a longer
period of time as the land is flat and avoid water to get drain off easily. Hence, the best
location of tank or may be artificial recharging point will the barren land in between the
buildings collecting discharge water from both Buildings. Similarly, for the main institutional
building, optimum location is situated behind collecting water from more than one
department. And the tank should be an underground one, so that the land can be best used by
building any useful structure above it. Hence based on the above detail studies, the 4 best
possible locations for underground tank or recharge point are recommended .

8.2. RAINWATER HARVESTING POTENTIAL OF DIFFERENT
BUILDING AT LODRA SCHOOL

Earlier in the context, rainwater harvesting potential has been explained and dealt in brief in
the section 5.1., hydrological analysis. Hence, now the rainwater harvesting capacity of
different building was found out with respect to same rainfall data.

As the rooftop surface area of different building including hall of residence and different
departmental building varies greatly with each other, thus amount of discharge produced or
rainwater runoff produced will be different. With the small ideas of rainwater harvesting
potential of different building, one can best take the advantage by of rainwater harvesting by
building the system in the more potential building.

Given below in the table no. 7, the detail rainwater harvesting capacity of the entire campus
buildings:

Page 47

Table No. 7 Rooftop Area & Runoff of all building

SL BUILDING NAME ROOFTOP RUN OFF(m³)
NO. AREA(m²) (rooftop area ×1.4 m)
1 All class room 1350 1890
2 Workshop 930 1302
3 Principal office 1426 1996.4
4 laybery building 2593 3630.2
5 hall 490 686

8.3. DETAIL MONTHLY HYDROLOGICAL ANALYSIS OF ALL BUILDING

Given below the table no.8 which gives the details monthly analysis of surface runoff
produced from the catchment areas of various building .Where the serial no.
denotes the building name as given in the table no. 2.

Page 48

TABLE NO.8: DETAIL MONTHLY HYDROLOGICAL ANALYSIS OF ALL BUILDING

SL AREA HARVESTING CAPACITY TOTAL
NO (m²) MONTHLY RAINFALL
J F M APR MY JN JUL AUG SEP OCT N D
1 1350 2.7 0 2.7 1.4 6.7 102.6 407.7 298.4 247.1 18.9 8.1 4.05 1100.3
5
2 930 1.86 0 1.86 0.9 4.6 70.7 280.7 205.5 179.2 13 5.6 2.8 766.72
3 1426 2.85 0 2.85 1.4 7.1 108.4 430.7 315.1 261 20 8.6 4.3 1162.3
4 2593 5.19 0 5.19 2.6 13 197.1 783.1 573.1 474.5 36.3 15.6 7.8 2113.5
5 490 0.98 0 0.98 0.5 2.45 37.24 148 108.3 89.7 6.9 3 1.5 399.55
6 820 1.64 0 1.64 0.8 4.1 62.32 247.7 181.2 150.1 11.5 5 2.5 668.5
7 362 0.72 0 0.72 0.4 1.81 27.5 109.3 80 66.25 5.1 2.2 1.1 295.1

8.4. DIMENSIONS OF TANK & COST OF CONSTRUCTION
Depending upon the hydrological analysis of runoff per month for different building, the size
of the underground tank was designed. As the design of the Sample tank i.e. school building.
Hence, the same procedure is being followed for all other buildings in a similar manner to
calculate the optimum dimension of tanks. Given below the results of optimum dimension of
underground tank (incase if it is build over the option of artificial recharge of underground
aquifer) in a tabular form in the table no. 9. Again, the optimum location of this tank is
carried out through GIS analysis which has already been discussed in the section 7.1. As we
know there are all together four optimum locations for artificial recharge of underground
tank or for underground storage tank for the study areas buildings which we have considered
here.

Page 49

The dimension of the tank was so chosen that depth of the tank should not be too deep, which
will create trouble like high cost of excavation, high cost of construction of retaining wall as
pressure increases at the rate of square of the height and finally there will be great difficulty
in maintenance. Hence the depth of the tank at max, was fixed to 5-6 m below the ground
level. Again, underground tank was chosen for best possible utilization of land by building
some playground or cycle stand above the tank.

Complete estimation and costing of sample building (school building) was done in the section
7.2 in the table 5 & 6. The same procedure was just repeated neglecting any variation in
thinness(30cm) of the tank for different tank size for ease of calculation and comparisons
between them.

For designing purpose, following data were assumed to be constant. These value cab be
change later on depending upon different situation.

Hence, No. of person consuming water from any one hall of residence was assumed to be
300.

Annual average rainfall was assumed to be 800 mm.

The rate of consumption, here was fixed to be 100liter/day.

Hence all other parameter and steps where same as previous and results of complete analysis
of tanks was tabulated in the table given below in table no. 9.

Page 50

TABLE NO. 9: DIMENSION OF TANK & ITS COST OF CONSTRUCTION FOR
VARIOUS BUILDINGS INSIDE THE LODRA SCHOOL

Sl Building Rooftop Runoff (m³) Reservoir Reservoir Dimention Cost
no. name area(m²) (rooftop capacity location of assumed of
area×1.4m) tank construction
1 Class room 1350 1890 1890 R1 4× 5×12 4,77,318.2
building
2 laboratory 930 1302
R2

3 principal 2593 3630.2 4932.2 5× 8× 12 9,54,638.8
building
4 Laybery 1426 1996.4
building

5 hall 362 506

Total cost of construction of underground tank Rs. 14,31,957

8.5. CALCULATION OF NUMBER OF DAYS SUPPORTED BY STORED
HARVESTED WATER IN TANK TO CONSUMER.

The two methods to distribute the stored harvested rainwater were already discussed in the
section 5.2 in detail. Here we need to calculate the no of days of lasting of stored rainwater
from different building inside the campus consumer. The number of consumer inside one
building was assumed to be fixed 300. Both the two methods of distribution of the stored
rainwater (Rapid depletion method(RDM) & Rational Method(RM)) were analyzed and
results shown in table below

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TABLE NO. 10: Analysis of distribution of stored harvested water by two methods:

Sl no. Building Rooftop Reservoir RM= R / 30 RDM = R/45
area(m²) capacity (days) (days)
1 All school room 1350 1890 63 42
2 laboratory 930
3 Principal office building 2593 4932.2 164.40 109.6
4 libiri building 1426
5 hall 490 2682.4 89.41 59.6

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CHAPTER – 9

CONCLUSION

This paper dealt with all aspect of improving the water scarcity problem in the Samarth
campus by implementing ancient old technique of rainwater Harvesting. Two alternatives
have been suggested for tank design, which takes separate approaches towards the
consumption of harvested rainwater. These results are given clearly in the table no. 10. Hence
from this table, we can draw out a conclusion that a huge amount of water got collected from
the rooftop surfaces of all the entire buildings. And if, this project is being done seriously and
implemented to the campus then behind Diploma department + workshop has a huge
harvesting potential. This reservoir should have to build for the storage of 4932.2 m3 of
water. Hence this tank has huge capacity of getting rainwater and on proper storage, this tank
can supply almost through out the year for about 300 consumers having a consuming rate of
100liter/day as calculated by rational depletion method. The water has almost the potential
amount of tank.

It is concluded that RCC tank which is to be constructed should be an underground one, so
that upper surface of the tank can be utilized economically for any land purpose such as
playground or garden or any such small structure.

Cost analysis has been done for all the tanks. And it was concluded that cost of construction
was not so high, if it is compared with problems which are faced by the students and staffs
inside the campus due to huge water scarcity. The other component of the harvesting systems
such as Guttering, First-Flush, and Filtration mechanism have also been reviewed and
designed for the hostels and all other building in details.

Hence it was finally concluded that implementation of rain water harvesting project for lodra
school will be the best approach to fight with present scenario of water scarcity in all aspects,
whether it is from financial point of view or from optimum utilization of land surface.
Therefore, water is highly a precious natural resource which is always in high demand in the
lodra school. and thus, RAINWATER HARVESTING for lodra school is highly
recommended. Page 53

* Location image *

Page 54

Storage tank

chapter-10 CANVAS SHIT

1 AEIOU SHEET :

Observation record sheet (AEIOU) is nothing but the observation which has been done on particular activity at a place.
Here, Observation Record Sheet (AEIOU) consists of 5 main elements which are listed below :
• A (Activities)
• E (Environment)
• I (Interaction)
• O (Objects)
• U (Users)

ACTIVITIES :
Activities are nothing but doing any type of work. Here, we observed various kinds of activities on laboratory. The
following activities we have observed :

• user
• Stakeholders
• Activities
• Story boarding
Happy
Sad
sad

Ideation canvas

• Activities
• Situation /context/location
• Props/possible solution
• People

Product development canvas

*purpose
*product experience
*people
*product function
*product features
*component
*customer revalidation
*reject, redesign, retain

x

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