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Rainwater Harvesting
Biome Environmental Solutions Pvt Ltd
Also:
PARADOX ?
Water Era in India
• Rainwater + shallow aquifer < 1850
• Surface water + shallow aquifer+ rainwater 1850 - 1970
• Deep aquifer + surface water + rainwater 1970 --2015
• Rainwater + ….+… 2015 >
The liberator – the hole in the ground which yielded precious
water
A hoary past – Well at Lothal 2600 BCE Photo Mrinalinee Vanarase
Did the Buddha drink from this well ? Sarnath 500 BCE
Local hydrologic cycle – seeking bio mimicry with rainwater harvesting
Rainfall pattern in Delhi NCR (varies between NOIDA and GURGAON
30 years data
MONTH DAYS QUANTITY (mm)
JAN 1.2 14.9
FEB 1 13.1
MAR 0.8 8.9
APR 0.5 6.7
MAY 0.8 22
JUN 2.1 44
JUL 7.4 188
AUG 7.9 191
SEP 4.0 94
OCT 0.8 18
NOV 0.1 5
DEC 0.4 5.5
TOTAL 27 611
RWH Potential (for every 100sqm of surface)
Nature of Surface
Runoff Coefficient
Runoff for average 30mm rain (in KL)
Annual runoff for 611mm (in KL)
Rooftop 0.8 2.4 48
Paved Area / Roads
0.5 1.5 30
Unpaved Areas / Garden
0.1 0.3 6
Case: RWH Potential as a % of Annual Demand
● Daily Demand = 15 KL (500 people x 30 lpcd)
● Annual Demand = 5475 KL (15 x 365)
● Total Campus = 3000sqm (~ 30,000sqft)
● Rooftops = 1500 sqm (50% of total area)
● RWH potential from rooftop = 733 KL (1500* 0.8 * 0.611 )
● Other Paved + Unpaved Areas = 1500 sqm
● RWH potential from non rooftops = 275 KL (1500×0.3×0.611)
● RWH Potential as a % of Annual Demand = 18% (733+275)/5475
Rainwater harvesting
components:
1) Catchment
2) Conveyance
3) Filtration
4) Storage
5) Recharge
<<< The saree is the
Catchment, conveyance
And filter !!!!!!
The collection and storage of rain for future productive use
EVERY ROOF CAN BE A CATCHMENT
Gutters
Gutter-for sloping roof transmitted through- PVC- Polycarbonate- GI
- Aluminium- Stainless steel
PVC GUTTER
Downpipes
Down water pipes made of - HDPE- PVC - Chains
Filters
Filters
RWH - Storage
● HDPE tank● Brick Masonry ● RCC tank
Rain barrel : easiest way to begin rainwater harvesting
Rainwater harvesting in an industry
Rain Barrels harvesting rooftop rainwater
Details of a rain barrel
Aluminium basket filter
Plastic basket filter
Storing in the Underground Tank
Ground Water Recharge
● Recharge Well● Deep Borewell Recharge● Recharge Trenches
The pit has reach the silt layer
Pit and concrete rings
Placing of the rings
The making of a recharge well
Procedure • Locate recharge well in the channel or off
the channel
• Make arrangements to remove silt and leaves before water enters recharge well
• Monitor the rate of recharge and decide on the number of recharge wells necessary for the catchment
Don’t forget the maintenance
Recharge pit around bore wells
Planning for RWH
Nature of Surface RWH Strategy
Rooftop Storage or Deep Aquifer Recharge
Paved Area / Roads Shallow Recharge – through trenches, Open Wells
Unpaved Areas / Garden
Shallow Recharge – through trenches, Open Wells
Sizing the RWH Structures
For Storage :
● Depending on usage and budget● Best to use existing storage structures● New storage structures can be sized for 30mm to 60mm rain
For Recharge : ● Calculate runoff for a 25mm-30mm rain and size accordingly
Designing
● Plot Size : 3000sqm
● Rooftop : 1500sqm,
● Non Rooftop : 1500sqm
● Rooftop Storage : 1500 litres filter and 36KL to 72KL storage
OR
● Rooftop Deep Aquifer Recharge :
● Non Rooftop 1500sqm – basic filters in drains and 1 recharge well or 5ft diameter and 30ft deep or Recharge Trench of 20KL capacity
Costs
S No Item Rate
1 4” PVC pipes – with fittings 80/- to 200/- per foot
2 6” PVC pipes – with fittings 280/- to 380/- per foot
3 Brick masonry storage/filter 10/- to 12/- per liter
4 Filter media 5/- to 7/- per liter
5 Commercially available filters - 500sqm
18,000/-
6 4KL Recharge Well 35,000/- to 40,000/-
6 16KL Recharge Well 85,000/- to 1,00,000/-
7 Deep bore with casing 30,000/- to 40,000/- for a 6” bore of upto 30m, 1000/- per meter
8 RCC storage 13/- to 18/- per liter
9 HDPE Storage (Sintex tanks) 6/- to 8/- per liter
10 Labour + Other misc 15% to 20% of material costs
Cramped Spaces
Local organizations/People that can help with the implementation
● CSE : Center for Science and Environment
● FORCE : Forum for Organised Resource Conservation and Enhancement
● R Balaji Engineering Co: GB Road : 011-66361953
● Flowell India, Mayur Vihar
● Geocon Groundwater consultants, Kalkaji (charges for feasibility study and design): 011-66262250
Maintenance
● Keep the terrace/campus clean● Clean Storm water drains● Dont let water stagnate anyplace● Clean out the filters 2 times during the year● Clean the storage tank
Best Practices
● Metering the borewell● Water Balance – Metering Demand
and Supply● Setup Rain Gauge● Metering the harvested rainwater
Monitoring
● Water Quality● Water Availability● Depth to Water (below ground level)● If the water is actually going into the
borehole (rate of recharge) !!.
Existing Success Stories in the neighbourhood
● Hero Moto Corp, Gurgaon● Surya Vihar, Gurgaon● Tex Corp Limited, Gurgaon● BPCL Housing Complex, NOIDA
Biome Environmental Solutions Pvt Ltd (Rainwater Club)
[email protected] www.rainwaterclub.org 1022, 1st floor, 6th Block,
HMT Layout, Vidyaranyapura, Bangalore – 560 097,
Phone : 080 41672790