A CONSERVATIVE STUDY OF ROOFTOP RAIN WATER HARVESTING AT SMT S. R. PATEL ENGINEERING

COLLEGE. DABHI-UNJHA OF TECHNOLOGY

PREPARED BY:

NAYI KAUSHAL R.

PATEL AMARISH H.

PATEL PRATIK M.

PATEL SACHIN B.

GUIDED BY: KHYATI PATEL

STUDY AREA

NAME:-SMT S. R. PATEL ENGIEERIN COLLEGE-DABHI, UNJHA.

LOCATION:-DABHI-UNJHA, DIST:MEHSANA

AREA:- 12 ACRES

NUMBER OF PEOPLE:-1200

TYPE OF ROOF:-CONCRETE

AMOUNT OF RAINFALL:-300mm

GROUND WATER POTENTIAL:-OVER EXPLOITED CATEGORY

FIG:-GROUND WATER POTENTIAL OF GUJARAT STATE

PROBLEM DEFINITION

•The campus of this institute is situated at the near Unjha city. •There are four departments and one boys hostels of residence for the students. Hence, total strength of campus including students and staffs people will be more than 1200. •Thus, with this present strength and also with the expansion programmes, campus should also increase its facilities and maintenance requirements. •If this demand is not met, then it will lead to water scarcity. •And, if it 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 will decline. •Hence, keeping in view all the above problems and status of campus, we should focus on accumulating the rain water.

RAINWATER HARVESTING SYSTEMS AND ITS FEATURES

Rainwater Harvesting is a simple technique of catching and holding rainwater where its falls. Either, we can store it in tanks or we can use it to recharge groundwater depending upon the situation.

ADVANTAGES:

•Roof top rainwater harvesting is one of the appropriate options for augmenting ground water recharge/ storage in urban areas where natural recharge is considerably reduced .

•Rainwater runoff which otherwise flows through sewers and storm drains and is wasted, can be harvested and utilized.

• Rainwater is bacteriologically safe, free from organic matter and is soft in nature.

•It helps in reducing the frequent drainage congestion and flooding during heavy rains in urban areas.

•The structures required for harvesting rainwater are simple, economical

and ecofriendly.

COMPONENTS OF ROOFTOP RAIN WATER HARVESTING SYSTEM

• Roof catchment

• Gutters

• Down pipe

• First flush pipe

• Filter unit

• Storage tank

• Recharge structure

•ROOF CATCHMENT

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 like a lawn or open ground.

•GUTTERS

Gutters are channels fixed to the edges of roof all around to collect and transport the rainwater from the roof to the storage tank. Gutters can be prepared in rectangular shapes and semi-circular.

•DOWN PIPE

Down pipe is the pipe that carries the rainwater from the gutters to the storage tank. Down pipe is joined with the gutters at one end, whereas the other end is connected to the filter unit of the storage tank.

•FIRST FLUSH PIPE

A first flush system can be incorporated in the roof top rainwater harvesting systems to dispose off the ‘first flush’ water so that is does not enter the tank.

•FILTER UNIT

The filter is used to remove suspended pollutants from rainwater collected from rooftop water. The Various types of filters generally used are Sand filters and slow sand filter.

•STORAGE TANK

Storage tank is used to store the water that is collected from the Roof tops. There are various options available for the construction of these tanks with respect to the shape, size, material of construction

AIMS AND OBJECTIVE

The present study aims to accumulate the useful rain water followed by some of these objectives:

• To suggest suitable methods to collect the rainwater, falling on the roof. •To suggest suitable site to construct a storage well where the rain water can be accumulated. •To suggest suitable methods to clean the collected ground water, so that it can be used for drinking and agricultural.

SCOPE OF STUDY

•The scope of the study covers the survey of the study area,

collection of data regarding the rainfall pattern, surface

cover type and the amount of runoff generated.

•The water demand of the institute will be assessed, and

the quantity of water required to be harvested will be

derived.

• Suitable water harvesting system will be designed for

collection and storage of the rainfall from the rooftop.

• Design of recharge well will be proposed to recharge the

ground water through artificial means using the excess

storm runoff.

• An approximate cost estimate for such a system will be

done.

EXPECTED OUTCOME

Rooftop Rainwater Harvesting is an artificial technique for storage of rain water, the expected outcomes of which will be: •It can meet potable and non-potable water demands and also control flooding. •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. •Campus can easily meet the potable water demand and also able to save money which is being spends for procuring potable-water. •It also helps in increasing the soil moisture condition and fertility factor of soil for plantation. •It tends to increase the greenery surrounding the campus, increasing aesthetic factor for a proper residential institute to live in.

METHODOLOGY

Based on the literature review work various method can be adopted as a solution to the problem from the engineering and economic point of view the best possible and feasible solution should be taken into consideration.

The selection of best alternative can be done after a detailed study of the problem and the roots of its cause.

A detailed methodology adopted for the study is shown in the figure below.

FLOW CHART OF METHODOLOGY

Problem Identification

Causes of problem

Survey in Data Collection

Amount of Rainfall Land Use Hydrological Analysis

Solutions for Problems

Direct Recharge Artificial Storage

Evaluation of Solutions

Cost Benefits Environmental Impact

Implementation of best alternative solution

1.) Problem Identification

The first step in the study methodology consists of identification of the problem with regard to the study area and its subsidiary effects on the study area are studied.

2.) Causes of the problem

The second step in the study methodology consists of the study of the causes of the problem with respect to the study area.

3.) Survey and Data collection

This is the most important phase of the study which requires the high grade of accuracy because the design is most important part of the project. The various data collected include

• Rainfall Data

• Land Use

• Hydrological Analysis

.

4.) Solutions for the problem

The present study aims to identify the suitable solution for these

problems. It is advisable to suggest suitable method for water

scarcity.

There are two types of methods for distributing the harvested

rainwater:-

• RATIONING METHOD (RM) • RAPID DEPLETION METHOD (RDM)

5.)Evaluation of alternative solutions

All the alternative solution will be evaluated on the basis of the capital investment, the durability and various other parameters and their are operation and maintenance cost. There are various parameters which are taken into the account with the all solution and all the factors listed below are evaluated:

•Cost

•Benefits

•Environment

6.)Implementation of best alternative solution

Considering all the solution and evaluating it, which has a least cost and maximum output will to be implemented.

DATA COLLECTION

(1)RAINFALL DATA COLLECTION

Smt. S. R. Patel Engineering College is located at 72’20’11.25”E longitude and 23’47’43.64”N latitude in near Unjha city. Average annual rainfall of Unjha is 300mm

It is followed that, Unjha is a small city and thus has a uniform average rainfall through out the city in all location. Thus monthly rainfall data of the Unjha city is given below in the table which is assumed to be same for the station of Smt. S. R. Patel Engineering College campus.

ANNUAL RAINFALL DATA LAST 10 YEARS IN UNJHA CITY

YEAR JAN FEB MAR APR MAY JUNE JULY AUG SEP OCT NOV DEC TOTAL

2002 0 0 0 0 0 8 79 157 76 0 0 0 320

2003 0 0 0 0 0 9 80 155 77 0 0 0 321

2004 0 0 0 0 0 10 78 151 75 0 0 0 314

2005 0 0 0 0 0 13 85 145 79 0 0 0 322

2006 0 0 0 0 0 12 75 149 82 0 0 0 318

2007 0 0 0 0 0 11 77 148 78 0 0 0 314

2008 0 0 0 0 0 8 79 154 79 0 0 0 320

2009 0 0 0 0 0 12 80 152 76 0 0 0 320

2010 0 0 0 0 0 8 77 150 77 0 0 0 312

2011 0 0 0 0 0 10 75 157 74 0 0 0 316

2012 0 0 0 0 0 9 78 160 75 0 0 0 322

2013 0 0 0 0 0 11 81 153 78 0 0 0 323

TABLE 2: MONTHLY RAINFALL DATA OF UNJHA OF 2012

MONTH RAINFALL

JANUARY 0

FEBRUARY 0

MARCH 0

APRIL 0

MAY 0

JUNE 11

JULY 81

AUGUST 153

SEPTEMBER 78

OCTOBER 0

NOVEMBER 0

DECEMBER 0

TOTAL 323

(2)DETERMINATION OF CATCHMENT AREA

Serial No. Building Name Rooftop Area(m2)

1 Jiviba Bhavan 2425

2 Amathabha Bhavan 2425

3 Boy’s hostel 1105

4 Work-shop 1125

5 Admin Building 1083

(3)COMPUTATON OF VOLUME OF RUNOFF Monthly Rainfall & Discharge Runoff from Engineering Building Jiviba

Bhavan

Sr no. Month Rainfall(mm) Discharge(m3)

1 JANUARY 0 0

2 FEBRUARY 0 0

3 MARCH 0 0

4 APRIL 0 0

5 MAY 0 0

6 JUNE 11 26.675

7 JULY 81 196.425

8 AUGUST 153 371.025

9 SEPTEMBER 78 189.15

10 OCTOBER 0 0

11 NOVEMBER 0 0

12 DECEMBER 0 0

TOTAL 323 783.275

Amount of Rainfall collected in throughout the year

0

50

100

150

200

250

300

350

RAINFALL(MM)

RAINFALL(MM)

Volume of water Collected from Rainfall throughout the year

0

50

100

150

200

250

300

350

Discharge(m3)

Discharge(m3)

(4)OPTIMUM DIMENSON OF TANK For Engineering building, total amount of water collected in one year =

size of the tank = 783.275 m3

Taking height of tank = 4m

Area of the base = 727.5/4 = 181.875 sqm.

We can take square base each of side = 14 m or rectangular base as per land availability. So our tank will be of dimensions 4x14x14 m (taking square tank) which is not economical.

As water is stored on yearly basis, Size of the tank will be equal to the excess amount of water left over after consumption. Hence, mostly excess amount of water assumed to be collected during the period of maximum rainfall – June, July, August and September.Maximum average rainfall of about 371.025m3 occurs in the month of August.

So let us construct two tanks of 200 m3 of capacity each.

Fixing the height of tank to be 4m Area of the base = 50 sqm

Hence taking the dimension of the tank as 4×5×10

DETAIL COST ESTIMATION OF SUMP (UNDERGROUND TANK)

Sr . Particular No Length

(m)

Breath

(m)

Height

(m)

Quantity

(m3)

1. Earthwork in Excavation 1 10.80 5.80 4.3 269.352

2. Cement Concrete 1:3:6 in

foundation

1 10.80 5.80 0.3 18.792

3. RCC work for

1.Long Wall

2.Short Wall

2

2

10.60

5.0

0.3

0.3

4

4

25.44

12

Total 37.44

4. RCC work for slab 1 10.60 5.6 0.2 11.87

5. 12mm plastering inside

with 1:2 Cement mortar

1.Long Wall

2.Short wall

2

2

10

5

4

4

80

40

Total 120

Abstract of Estimate Cost With RCC Wall

Sr no Particular Quantity Rate Cost(Rs)

1. Earthwork in excavation 269.35 100Rs/m3 26935.2

2. Cement concrete 1:3:6 in foundation with brick ballast

18.792 2700 Rs/m3 50738.4

3. RCC work for side walls and

slab

49.31 2700 Rs/m3 133137

4. 12mm plastering with 1:2 cement mortar

120 88 Rs/m2 10560

Total 221370.6

5. Contingency + work charges establishment

3%+2%=5% 11068.53

6. Engineering profit 10% 22137.06

Grand total 254576.19

FIRST FLUSH MECHANISMS

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, 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.

OPTIMUM LOCATION OF TANK / UNDERGROUND RESERVOIR RECHARGING POINT

Following points should be kept in mind while deciding the location of the tank

•Its location should be such that cost of plumbing to collect the water in less

•Tank should not located very near to the existing structures.

•It should be located on a leveled ground.

•There should not be any vegetation like a tree very near the tank.

•It should not constructed in clayey soil.

•Based on the above criteria the optimum locations of the tanks are shown in the figure below

RAINWATER HARVESTING POTENTIAL OF DIFFERENT BUILDING AT SRPEC CAMPUS

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 of rainwater harvesting by building the system in the more potential building.

Given below in the table, the detail rainwater harvesting capacity of the entire campus buildings:

Serial no. Building Name Rooftop area(m2) Runoff(m3)

(rooftop area

x0.3m)

1. Jiviba Bhavan 2425 727.5

2. Amathabha Bhavan 2425 727.5

3. Boy’s hostel 1105 331.5

4. Work-shop 1125 337.5

5. Admin Building 1083 324.9

DETAIL MONTHLY HYDROLOGICAL ANALYSIS OF ALL BUILDING

Sr

no

Area

(m2)

Harvesting capacity (Monthly Runoff) Total

J F M AL MY JN JL AU S O N D

1. 2425 0 0 0 0 0 26.675 196.425 371.025 189.15 0 0 0 783.27

5

2. 2425 0 0 0 0 0 26.675 196.425 371.025 189.15 0 0 0 783.27

5

3. 1105 0 0 0 0 0 12.155 89.505 169.065 86.19 0 0 0 356.915

4. 1125 0 0 0 0 0 12.375 91.125 172.125 87.75 0 0 0 363.375

5. 1083 0 0 0 0 0 11.913 87.723 165.699 84.474 0 0 0 349.805

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

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 500. 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

Sr no Building Rooftop area(m2)

Reservoir Capacity (R)

RM = R/30 (days)

RDM= R/45 (days)

1. Jiviba Bhavan 2425 727.5 24.25 16.167

2. Amathabha

Bhavan

2425 727.5 24.25 16.167

3. Boy’s hostel 1105 356.915 11.89 7.93

4. Work-shop 1125 363.375 12.11 8.075

5. Admin

Building

1083 324.5 10.83 7.22

CONCLUSION

• Hence from the above tables, 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 Engineering building Jiviba Bhavan and Amathabha Bhavan has a huge harvesting potential. This reservoir should have to build for the storage of 727.5 m3 of water. Hence this tank has huge capacity of getting rainwater and on proper storage, this tank can supply a great amount of water.

•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 cycle stands 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.

• Hence it was finally concluded that implementation of ROOFTOP RAINWATER HARVESTING PROJECT to the campus of SRPEC 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.

THANK

YOU