This document proposes a project to capture rainwater and treat greywater from a washroom at a cement works plant in Sri Lanka to reduce water usage. It would harvest an estimated 2,313 liters of rainwater per day, treating 4,500 liters of greywater daily. This would save an estimated 2,305 cubic meters of water annually, reducing costs by about 207,450 Sri Lankan rupees per year with a payback period of 2 years and 8 months. The project aims to make the plant more sustainable and reduce its environmental impact through efficient water usage.

1. Strength. Performance. Passion.
Efficient Water Usage Improvement(RCW)
Theekshani Jayaweera NJS (Trainee - Environment)

2. Background of the project
Scope - capturing the water from rain & treat the gray water from wash room and
reuse them for toilet flushing in RCW changing room premises
Ruhuna cement works plant is situated in low country wet zone. Average annual
rainfall in wet zone is 2000-2500mm. RCW site average annual rainfall is
2570mm
As new trend to sustainable development and green technologies this will help to
move our organization good picture as eco friendly industry.
rainwater harvesting and efficient water usage(RCW), 2016-05-17 © 2015 2

3. Significance of the Project
In current situation water requirement is fulfilled by the National water supply
and drainage board.
Average water requirement is about 3000 m3 per month from the NWSDB.
more than 450m3 is used for the changing room domestic water usage.
Objective of this project is to reduce the water supply from the NWSDB by
rainwater harvesting and gray water treatment system. This is a long term cost
effective sustainable design.
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4. Capacity
Average annual rainfall in the site
Total catchment area
Catchment coefficient
Average rainwater that can be captured per day
2570mm
365m2
0.9
2313 L
Average Daily water requirement for the
changing rooms
Water requirement for showers and sinks 70%
Water requirement for toilet flushing 30%
15 000 L
10 500L
4 500L
Daily Wastewater treatment capacity 4000L
Total daily water saving percentage 42%
Annual water saving
Annual water requirement
2305 m3
5475
rainwater harvesting and efficient water usage(RCW), 2016-05-17 © 2015 4

5. Diagram of the RWHS design
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6. Gray water treatment system
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7. Cost analysis- RWHS
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Purpose amou
nt
LKR
Gutters Already available
Screen 3 5 000
First flush floating ball device 3 6 000
1000L storage tank 3 Reusable IBC tank/already available tanks
Pump 1 50 000
Pressure accumulator 1 40 000
plumbing 60 000
Cartridge filter 10 µm 1 8 000
Base for above ground level tank(1000L) 1 3 000
Miscellaneous 30 000
Fixed cost 202 000
Operating cost Per
Year
50 000

8. 8rainwater harvesting and efficient water usage(RCW), 2016-05-17 © 2015
Purpose amount LKR
Storage tank
5 (5000L)
Reusable IBC tank 5
Digging ( for 2 IBC tank) 50 000
Plumbing 30 000
Pump (underground to changing room first floor ) 1 25 000
Accumulator 1 20 000
sand filter 1 75 000
Chlorine treatment (chlorine dosing pump) 2 120 000
Miscellaneous 50 000
Fixed cost 370 000
Operating cost
For chlorine
treatment
4 000
Gray water treatment plant

9. 9rainwater harvesting and efficient water usage(RCW), 2016-05-17 © 2015
• Total fixed cost = 572 000
• Annual operating cost = 54 000
• Annual water saving = 2305 m3
• Annual water saving percentage = 42 %
• Annual cost saving = 207 450LKR
• Payback period = 2 years and 8 months
Cost benefit analysis

10. 10rainwater harvesting and efficient water usage(RCW), 2016-05-17 © 2015
Project implementation time frame
# Activity
Month 1 Month 2 Month 3 Month 4 Month 5 Month 6
W
1
W
2
W
3
W
4
W
1
W
2
W
3
W
4
W
1
W
2
W
3
W
4
W
1
W
2
W
3
W
4
W
1
W
2
W
3
W
4
W
1
W
2
W
3
W
4
1
Identifying suitable area for
project
2
Prepare project proposal and
get approval
3
Further Improvement of the
design according to
discussion panel
4
Get quotation (by
procurement division )
5 Build and construction
6
Water testing and
commissioning

11. •
Thank you…
For the sustainable performance according to our 2030
plan
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