UNDER THE GUIDANCE OF

Dr. B. Nagamalleswara RaoProfessor & Head

DESIGN AND IMPLEMENTATION OF ROOFTOP RAINWATER HARVESTING SYSTEM(RRHS)

FOR D-BLOCK OF VNRVJIET CAMPUS By

• G.Sandhya Rani (10071A0174)• J.Sai Kiran (10071A0176) • K.Sravan kumar (10071A0185)

Department of Civil Engineering VNR Vignana Jyothi Institute of Engineering &Technology,

Bachupally, Nizampet (S.O), Hyderabad-500090, AP

• B.Rani (11075A0117)• M.Mahesh (11075A0124)

CONTENTS

1. INTRODUCTION

2. OBJECTIVES

3. LITERATURE REVIEW

4. METHODOLOGY

5. TIME SCHEDULE

6. APPLICATIONS

7. CONCLUSION

8. REFERENCES2

1.INTRODUCTION

Water is the most common or major substance on earth, covering more than 70% of the planets surface. The total amount of water on earth remains constant.

The rapid growth in population together with industrial development, are putting stress on the natural ecosystems.

Water supply mainly depends on the natural water bodies likes lakes and artificial water bodies like reservoirs etc.

Due to the Urbanisation and rapid growth in the population many lakes has been lost and the majority of the present were polluted .

This results in the imbalance of demand and supply of water.

To overcome supply shortages, many households, businesses and industries fall back on groundwater reserves. The number of bore wells increased.

1.INTRODUCTION

This is leading to the fall in the ground water table.

One possible strategy could be the usage of rainwater in order to overcome the shortage of water.

Rain water harvesting means to make optimum use of rain water at the place where it falls i.e. conserve it and not allowing it to drain away.

The water can be used as drinking water, water for livestock, water for irrigation or to refill aquifers in a process called ground water recharge.

The rainwater falling on roof of residential buildings and institutions can be an important contribution to the availability of water.

Hydrological cycle

ABSTRACT

Roof water harvesting is being widely promoted as a panacea for the growing drinking water crisis in India and many underdeveloped and developing countries. This project analyzes the scope, physical feasibility and economic viability of roof water harvesting systems. The economic viability as a supplementary source of domestic water supply seems to be poor in urban areas, when compared to augmenting the supplies from the existing public systems. The incredibly low rates charged for domestic supplies by urban water utilities and government subsidies for RWHS would not only lead to the urban elite increasing their access to water supplies, while the burden on water utilities would remain unchanged. This will lead to greater inequities in access to water supplies. At the same time, in rural areas with dispersed populations and hilly areas, RWHS may be economically viable as a supplementary source to already existing public water supply schemes.

6

2.OBJECTIVES

Design of rain water harvesting system components.

Implementation of rain water harvesting system in D Block of

VNRVJIET campus

Cost benefit analysis

3. LITERATURE REVIEW

ANIL AGARWAL (2013): Manual on Urban Rainwater Harvesting “Catch Water Where it Falls”

KIRAN. A, NIKHIL. T, R HARISH, J KULKARNI (2012): Harvested Rain Water for Drinking- Research Paper.

ROHITASHW KUMAR, THAMAN S, AGRAWAL G. and SHARMA POONAM(2011): Rain Water Harvesting and Ground Water Recharging in North Western Himalayan Region for Sustainable Agricultural Productivity- Research Paper.

M. DINESH KUMAR, ANKIT PATEL(2005) : Rainwater Harvesting in the Water-scarce Regions of India potential and Pitfalls-Research paper

ACHAYRA, B. P. (2004). Managing Water Sector Institution - HMWSSB Experience (Presentation). Hyderabad Metropolitan Water Supply and Sewerage Board, Hyderabad.

SIVARAMAN , K.R. & THILLAI GOVINDARAJAN S.. (2003), Manual on Rainwater Harvesting. Chennai, Akash Ganga.

ARIYABANDU R. D. S. (2003). Very-Low-Cost Domestic Roof Water Harvesting in the Humid Tropics: Its Role in Water Policy. Sri Lanka Domestic Roofwater Harvesting Research Programme.

4. METHODOLOGY

Collection of the building data.

Collection of rainfall data of past 10 years.

Design of RWHS components

Implementation

COMPONENTS OF RWHS

10

• Roof Catchment• Drain pipes• Down pipes• First Flush Pipe• Storage Tank• Recharge Pit

Drain Pipe

Storage tank

Down pipe

First Flush Pipe

DESIGN OF RWHS COMPONENTS

1.Roof catchment

2.Calculation of Volume of Runoff

3.Design of Rectangular Storage Tank

4.Design of Conduits

5.Design of Recharge Pit

11

DESIGN OF RWHS

1.Roof catchment: • The area of the roof from which the rain water is

collected.• The total roof area of D block = 2351 m2

12

13ALL DIMENSIONS ARE IN MM

ROOF PLAN

DESIGN OF RWHS

Area of catchment = 2351 m2

Annual average rainfall = 887 mm

= 0.887m

Runoff co-efficient = 0.85

Volume of runoff = area of catchment x annual

average rainfall x runoff

co-efficient

= 2351 x 0.887 x 0.85

= 1773 m3/yr 14

2.Calculation of Volume of Runoff:

DESIGN OF RWHS

Average value of highest

rainfall in rainy days = 94mm =0.094m

Volume of Runoff = 2351 x 0.094 x 0.85

= 188 m3/day

For economical design considering half of the discharge as volume of tank

Volume of tank = 94 m3

15

DESIGN OF RWHS

Assume depth of tank = 2m

Area of tank = volume of the tank/depth

= 94/2 = 47m2 = 50m2(approx.)

Taking Length: Breadth ratio as 2:1

L = 2B

2B x B = 50

B = 5m

L = 10m

16

3.Design of Rectangular Storage Tank:

ALL DIMENSIONS ARE IN METERS

Storage Tank

EXISTING PIPE DETAILS

S.No Diameter(mm)

No of Pipes Length of Pipe(m)

1 110 4 22.00

2 110 2 21.77

3 140 1 21.34

4 150 1 21.40

5 150 1 21.37

6 150 1 14.64

7 150 1 11.00

17

DESIGN OF RWHS

Taking diameter of pipe = 110mm = 0.11m

Average value of highest

rainfall in rainy days = 94mm =0.094m

Taking number of pipes = 10

Volume of water that can be

discharged through 10 pipes = 2351×0.094×0.85

= 188 m3/day

Volume of water that can be

discharged through each pipe = 188/10 = 18.8m3/day

= 2.17×10-4 m3/sec

4.Design of Conduits:

DESIGN OF RWHS

The recharge pit is designed for one third of discharge

Volume of recharge pit = 62m3

Assuming depth of recharge pit = 3m

Area of the recharge pit = 62/3 = 20 m2

Taking Length: Breadth ratio as 2:1

L = 2B

2B x B = 20

B = 3.2m

L = 6.4m 19

5.Design of Recharge Pit:

ALL DIMENSIONS ARE IN MM

ESTIMATION & COSTING

Storage Tank Earth Work Excavation 

Length of excavation

 Width of excavation

 Depth of excavation

 Total volume of excavation

Cement Concrete in Foundation

 Length at sides

 Width at sides

 

 

= 10 +(0.3/2) + (0.3/2) = 10.3 m

 = 5 - (0.3/2) -(0.3/2) = 4.7 m

 = 2 + 0.3 + 0.3 = 2.6 m

 = Length x Width x Depth

= 10.3 x 4.7 x 2.6

= 125.86 m3

 

 = 10 + (0.3/2) + (0.3/2) = 10.3 m

 = 5 -(0.3/2) - (0.3/2)= 4.7 m

  20

Depth of layer

 Total volume of cement concrete in

foundation Brick Work (Long wall & Short wall Method) 

Taking width of wall 30cm we get

Long wall length

 Short wall length

 Long wall quantity

 Short wall quantity

 Total quantity

= 0.3 m

 = Length x Width x Depth

= 10.3 x 4.7 x 0.3

= 14.523 m3

  

 

= 10 +(0.3/2) +(0.3/2) = 10.3 m

= 5 -(0.3/2) -(0.3/2) = 4.7 m

 = 2 x 10.3 x 0.3 x 2 = 12.36 m3

= 2 x 4.7 x 0.3 x 2 = 5.64 m3

 = 12.36 + 5.64 = 18.00 m3

21

Plastering Work

 Plastering on length side

Plastering on width side

Plastering on flooring

Total area of plastering

R.C.C Work for Slab

Length of Slab

Width of Slab

Depth of slab

Total Quantity

= 2 x 10 x 2 = 40 m2

= 2 x 5 x 2 = 20 m2

= 10 x 5 = 50 m2

= 40 + 20 + 50 = 110 m2

= 10 m= 5 m= 0.15 m= Length x Width x Depth= 10 x 5 x 0.15= 7.5 m3

22

Recharge Pit Earth Work Excavation

 Length of excavation

 Width of excavation

 Depth of excavation

Total volume of excavation

 

Brick Work (Long wall & Short wall

Method)

 Taking width of wall 30cm we get

Long wall length

 Short wall length

 

= 6.1 +(0.3/2) +(0.3/2) = 6.4 m

 = 2.9 -(0.3/2) -(0.3/2) = 2.6 m

 = 2 m

= Length x Width x Depth

= 6.4 x 2.6 x 2= 33.28 m3

= 6.1 + (0.3/2) +(0.3/2) = 6.4 m

 = 2.9 -(0.3/2) -(0.3/2) = 2.6 m

23

Long wall quantity

 Short wall quantity

 Total quantity

 

Plastering Work

 Plastering on length side

Plastering on width side

Total area of plastering

= 2 x 6.4 x 0.3 x 2 = 7.68 m3

 = 2 x 2.6 x 0.3 x 2 = 3.12 m3

 = 7.68 + 3.12 = 10.80 m3

 

 

 = 2 x 6.4 x 2 = 25.6 m2

= 2 x 2.6 x 2.82 = 10.4 m2

= 25.6 + 10.4 = 36 m2

 

 

24

ESTIMATION OF MATERIALS

Storage Tank (1:2:4)Cement Concrete in Foundation

Total Volume

Volume

Add 25% for Wastage

Cement

Sand

Coarse Aggregate

 Brick Work

Total Volume

For 1 m3 number of bricks

For 18 m3 number of bricks

= 14.523 m3

= 14.523/1+2+4 = 2.07 m3

= 2.07 + 0.25 x 2.07 = 2.593 m3

= 2.593 m3 = 75 Bags

= 2.593 x 2 = 5.186 m3

= 2.593 x 4 = 10.373 m3

 

 = 18 m3

= 500

= 18 x 500 = 9000

25

Wet Volume

 Add 25% for Wastage

Net Volume

Cement

Sand

 Plastering

Total Area (12 mm Thick)

Wet Mix Mortar

Add 30% for Filling Joints

Increase 25% by Dry Volume

= 18 – (9000 x 0.19 x 0.09 x 0.09)

= 4.15 m3

= 4.15 + 0.25 x 4.15 = 5.186 m3

= 5.186/1+4 = 1.037 m3

= 1.037 m3 = 30 Bags

= 1.037 x 4 = 4.15 m3

 

 = 110 m2

= 12 x 110 / 1000 = 1.32 m3

= 1.32 x 1.3 = 1.716 m3

= 1.716 x 1.25 = 2.145 m3

26

For 1:4 Cement Sand Mortar

Cement

Sand

 Steel Bars

Main Steel

 Number of Straight Bars

Number of Bent-Up Bars

Length of Straight Bar

Length of Bent-Up Bar

Total Length of Straight Bars

Total Length of Bent-Up Bars

= 2.145/1+4 = 0.43 m3

= 0.43 m3 = 13 Bags

= 0.43 x 4 = 1.716 m3

 

 

 = 84

= 84 – 1= 83

= 10 – 0.04 + (18 x 0.01) = 10.14 m

= 10.14 + 0.08 = 10.22 m

= 84 x 10.14 = 851.76 m

= 83 x 10.22 = 848.26 m

27

Total Weight of Main Steel (10 mm

Diameter Bars @ 0.62 kg/m)

 Distribution Steel

Number of Straight Bars

Number of Bent-Up Bars

Length of Straight Bar

Length of Bent-Up Bar

Total Length of Straight Bars

Total Length of Bent-Up Bars

Total Weight of Distribution Steel (8

mm Diameter Bars @ 0.39 kg/m)

 Total Weight of Steel in Storage Tank

= (851.76 + 848.26) x 0.62 = 1054 kg

 

 

 = 20

= 20 – 1 = 19

= 5 – 0.04 + (18 x 0.008) = 5.104 m

= 5.104 + 0.08 = 5.184 m

= 5.104 x 20 = 102.08 m

= 5.184 x 19 = 98.49 m

= (102.08 + 98.49) x 0.39 = 200.57 kg

 

 = 1054 + 200.57 = 1254.57 kg

= 12.54 Q

28

Recharge Pit

Total Volume

For 1 m3 number of bricks

For 10.8 m3 number of bricks

Wet Volume

 

Add 25% for Wastage

Net Volume

Cement

Sand

= 10.8m3

= 500

= 10.8 x 500 = 5400

= 10.8 – (5400 x 0.19 x 0.09 x 0.09)

= 2.489 m3

= 2.489 + 0.25 x 2.489 = 3.11

= 3.11/1+4 = 0.622m3

= 0.622m3 = 18 Bags

= 0.622 x 4 = 2.48m3

29

COST FOR WORK AND MATERIALS

Cost of Earth Work in Excavation per

cubic meter

Cost of Cement Concrete in Foundation

per cubic meter (1:4:8)

Cost of Total Brick Work per cubic meter

Cost of Earth Work in Filling per cubic

meter

Cost of R.C.C Work per cubic meter

(Including Steel)

Cost of Plastering per square meter (12

mm thick) (1:3)

Cost of Pipe per meter (75 mm diameter)

Cost of One Bent (75 mm diameter)

= Rs.100/-

 

= Rs.2,000/-

 

= Rs.1,300/-

= Rs.20/-

= Rs.3,500/-

 

= Rs.60/-

 

= Rs.35/-

= Rs.20/-30

Cost of One Opening on R.C.C Slab

Cost of One Gate Valve

Cement(per bag)

Fine Aggregate(per cubic meter)

Coarse Aggregate(per cubic meter)

Steel(Per Quintal)

Brick(Per Piece)

Cost of Storage Tank:

Cost of Earthwork in excavation

 

 

 Cost of cement concrete in

foundation

= Rs.400/-

= Rs.200/-

= Rs.240/-

= Rs.1120/-

= Rs.1200/-

= Rs.4500/-

= Rs.5/- 

= Volume of excavation x Cost of

excavation per cubic meter

= 125.866 x 100 =Rs.12586.6/-

= Volume of cement concrete x Cost

of cement concrete per cubic meter

= 14.523 x 2000

=Rs.29046.00/-

31

Cost of Brick work

 

 

 

Cost of Plastering

 

 

 

Cost of RCC work in slab

= Volume of Brick work x Cost of

Brick work per cubic meter

=18 x 1300

= Rs.23400.00/-

= Total Area of Plastering x Cost of

Plastering per cubic meter

= 110 x 60

= Rs. 6600.00/-

= Volume of RCC work in slab x Cost

of RCC work in slab per cubic meter

= 7.5 x 3500

= Rs.26250.00/-

32

Cost of Recharge pit

Cost of Earthwork in excavation

 

 

 

Cost of Brick work

 

 

Cost of Plastering

 = Volume of Earthwork in excavation x Cost of Earthwork in excavation per cubic meter

= 33.28 x 100

= Rs.332.80/-

= Volume of Brick work x Cost of

Brick work per cubic meter

= 10.8 x 1300

= Rs.14040.00/-

= Total area of Plastering x Cost of

Plastering per cubic meter

= 36 x 60

= Rs.2160.00/-

33

COST OF PROJECTCost of the Project = Total Cost of work for storage tank + Total Cost of work

for Recharge Pit + Cost of Materials

Cost of the Project = Rs. 97882.6 + Rs. 16532.6+ Rs.240098.32

= Rs. 354513.52/-

Cost of Tools and Plants =1.5% of Cost of Project

=0.015 x 354513.52

= Rs.5317/-

Cost of Contingence = 5% of Cost of Project

= 0.05 x 354513.52

= Rs.17,725.68/-

Cost of Work Charge Establishment =2% of Cost of Project

= 0.02 x 354513.52

= Rs.7090.27/-

Total Cost of Project = Cost of the Project + Cost of Tools and Plants + Cost of Contingence + Cost of Work Charge Establishment

= Rs.4,48,459/-

34

COST BENEFIT ANALYSIS

Volume of water collected in a year

through RWHS

 

Volume of water collected in year

excluding 20% overflow

 We use daily 1 tanker of 20,000 liters

capacity

 Number of tankers

 Cost of one tanker

 Volume of water used per day

= 1773 m3/yr

= 1773000 lit/yr

 

 = 1773000 x 0.8

= 1418400 lit/yr

 

 

 = 1

 = Rs. 1000/-

 = No of tankers x Capacity of tankers

= 1 x 20,000

= 20,000 liters35

 Cost of one liter of water

 

 Total cost of water purchased per

year

 

 

 

 Total cost of water that can be

collected by RWHS

 Amount of money saved

Total amount spent on constructing

tank and recharge pit

Number of years required to recover

the amount spent on construction

= Rs. 0.05/-

 

 = Cost of water purchased in a day x

No of days water used in a year

= 1000 x 242

= Rs. 2,42,000/-

 = 1418400 x 0.05

= Rs. 70,920/-

 = Rs. 70,920/-

 

= Rs. 4,48,458/-

 

= 6.3 Years

36

RAINFALL DATA

Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec2003 0 10.7 11.7 27.3 0 65.5 265 144 54.9 168 0 0

2004 38.9 0.6 32.4 59 41.9 29.4 221 68.7 118.2 72.8 0.2 0

2005 39.7 10.3 18.7 24.8 21.8 88.9 369 115 220 221 0 0

2006 0 0 41.8 67.9 100 83.8 192 237 206 15.7 52.2 0

2007 0 0 0 23 11.5 113.3 92.8 214 266 18.1 21 0

2008 0 69.2 166 13.8 20.8 40.2 96 464 199 48 48 0

2009 0 0 2.1 23 17.3 69 55.5 353 145 69.6 28 4.4

2010 6.3 2.7 0 0.6 17.4 150.8 339 216 231 55.5 46.8 15.2

2011 0 25.2 1.7 6.9 1.7 35.6 185 234 76.9 70 8.4 0

2012 0.3 0 0 18.3 4.8 132 232 143 114 78.1 39.5 0

2013 0.3 17 0 74.5 10.2 203.2 197 124 155 239 14 0

37

5.TIME SCHEDULE

38

S.NO ACTIVITY DURATION DATES

RESCHEDULED DATES STATUS

1. LITERATURE REVIEW

6 WEEKS 23.09.2013 -

02.11.2013

23.09.2013 -

02.11.2013COMPLETED

2. DATA COLLECTION 4 WEEKS 04.11.2013 -

30.11.2013

04.11.2013 -

30.11.2013COMPLETED

3. DESIGNING 9 WEEKS 02.12.2013 -

03.02.2014

02.12.2013 -

03.02.2014COMPLETED

4. COST BENEFIT ANALYSIS AND

DOCUMENTATION

4 WEEKS 04.02.2014 -

04.03.2014

04.02.2014 -

31.03.2014COMPLETED

5 IMPLEMENTATION 4 WEEKS 05.03.2014 5.04.2014 ONWARDS

6. APPLICATIONS

To overcome the inadequacy of water to meet our demands.

To arrest decline in ground water levels.

To increase availability of ground water at specific place and time and utilize rainwater for sustainable development.

To increase infiltration of rainwater in the subsoil which has decreased drastically in urban areas.

To reduce the expenditure spent on water.

7. CONCLUSION

Since VNR Vignana Jyothi Institute of Engineering and Technology has no water supply through pipes, the institute has to buy the water through tankers.

Daily 1 tanker supply the water to the institute, each tanker costs Rs1000/-, having a capacity of 20,000 liters. It is taking Rs.4,48,459/- for total construction of tank and recharge pit.

The amount of money saved in each year through rain water harvesting is Rs.70,920. The amount spent will be recovered in 6.3 years.

In order to save the expenses to some extent on buying water this “Rooftop Rainwater Harvesting System” has been designed.

The water which we get from roof of the building during rainy days are collected and stored.

The water which is collected is set to re-use for gardening, flushing purposes so that the expenses can be reduced to some extent. 40

8. REFERENCES

ANIL AGARWAL (2013): Manual on Urban Rainwater Harvesting “Catch Water Where it Falls”

KIRAN. A, NIKHIL. T, R HARISH, J KULKARNI (2012): Harvested Rain Water for Drinking- Research Paper.

ROHITASHW KUMAR, THAMAN S, AGRAWAL G. and SHARMA POONAM(2011): Rain Water Harvesting and Ground Water Recharging in North Western Himalayan Region for Sustainable Agricultural Productivity- Research Paper.

RAMACHANDRAIAH, C. (2007). Hyderabad’s Water Issues and the Musi River, Need for Integrated Solutions. Draft version of the Paper presented in the International Water Confe-rence, Berlin during 12-14 September 2007.

ACHAYRA, B. P. (2004). Managing Water Sector Institution - HMWSSB Experience (Presen-tation). Hyderabad Metropolitan Water Supply and Sewerage Board, Hyderabad.

SIVARAMAN , K.R. & THILLAIGOVINDARAJAN S.. (2003), Manual on Rainwater Har-vesting. Chennai, Akash Ganga.

ARIYABANDU R. D. S. (2003). Very-Low-Cost Domestic Roof Water Harvesting in theHu-mid Tropics: Its Role in Water Policy.Sri Lanka Domestic Roofwater Harvesting Research Pro-gramme.

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