BRIEF OVERVIEW
Situated in Whitefield, Bangalore, Sisa Swiss-Indo Academy is a private school recognized by govt. of Karnataka - founded in 1981. It has a pre-primary, primary and high school, with about 630+ children and 50+ staff. Everyday about 700 people visit the campus. There are 2 main buildings in the school – BEVERIN and PASCUMIN. The school premise is over 4 decades old and has been gradually improved.
 |
| Sisa Swiss-Indo Academy, Whitefield, Bangalore |
Water situation in Whitefield:
Whitefield is located
towards the south-east of Bengaluru and has emerged as the heart of Bengaluru’s
IT corridor and has seen rapid development over the last decade. Cauvery water
pipeline work for these areas only began as late as 2017, and the suburban
population here mainly depends on borewell water. In some areas, the water level has
reached 1,700 ft below the ground, which previously used to be between
300-500ft. In many places the borewells have dried up.
Water situation in Sisa Kendra:
With no choice of Municipal water
supply, Sisa Kendra school opted for a bore-well that was established in
(or about) 1992, dug for 300ft depth, that used to supply water to all the
bathroom-toilets and landscape needs, but ran dry in 2009. Thus, the school had
to start depending on tankers, throughout the year. Additionally,
drinking water cans were bought (120LPD) every day. It is in this context that
BIOME’s help was sought in 2012, to be able to augment supply.
PROPOSAL
FOR WATER MANAGEMENT
Challenge:
· The average daily domestic demand (for all purposes
other than drinking) was 5000LPD in 2012. This works out to a per capita daily
demand of about 8 litres, which was judicious use of water. The current per
capita daily demand has now gone up to 10 litres.
· Hefty amounts were being paid for ensuring supply
of water through tankers, and this source is also unpredictable with private
tanker companies.
Structure study & area calculation:
Given that the catchment areas on
campus is rooftop and open areas, the following table shows us the potential
for RWH
|
Catchment description
|
Area
(sqm)
|
Annual Run-off 970mm (KL)
|
Run off for 30 mm rain in KL
(average rain)
|
Run off for 60 mm rain in KL (heavy rain)
|
|
Total
Campus (0.5 acres)
|
6069
|
5887
|
182
|
364
|
|
BEVERIN
(4500sqft, 90% runoff coefficient)
|
413
|
361
|
11
|
22
|
|
PASCUMIN
(5000sqft, 90% runoff coefficient)
|
459
|
401
|
12
|
25
|
· Total
rooftop and surface area = 4500 sqft + 5000 sqft = 9500 sqft
·
Average
annual rainfall in Bangalore is 970mm
·
Total
volume of rainwater harvested: 361+401
KLPD
·
There is potential
to harvest upto ~150 days of water (361+401/5KLPD) for domestic
consumption.
Biome’s Intervention of an RWH system:
After a careful study of the scenario,
BIOME team proposed both rainwater storage and ground water recharge strategies
in the recommended order of implementation.
Phase 1
· Building a 30KL sump next to the existing sump (5KL capacity) near
BEVERIN and connected to the old sump on the top for overflow.
· Redirection of 13 rainwater downpipes from Beverin into this new
underground brick masonry sump after filtration.
· Redirection of all downpipes from Pascumin
rooftop and storing of water in the new sump.
· Redirection of rainwater from the old sump to the
dried borewell.
Phase 2
·
Further treatment and usage of the
overflow water from the septic tank for gardening. (Yet to be implemented)
IMPACT
Water demand vs supply -
- The average daily domestic demand (for all purposes other than
drinking) has been increasing due to increase in student intake. The
daily demand has gone up to 6500-7000 litres, from the erstwhile 5000
litres in 2012. This works out to a per capita daily demand of about 10
litres currently.
- With implementation of the RWH system in 2012, initially SISA
Kendra was able to supplement 50%- 55% of its water needs. With current demands, the RWH supply suffices only for 45% of their
needs.
- The first rain filter water is also captured in a 3’ x 3’ x 2’ tank and used for their landscaping needs. The support staff are
very careful and ensure that wastage of water is minimal.
Cost analysis and savings –
·
The overall installation cost for RWH
system was 5Lakhs.
·
With an average offset from annual RWH
of 762 KL, the school is able to save ~ INR 76,200 annually, by reducing
its dependence on tanker supply by 55%.
·
There is an annual expenditure of 1Lakh
on buying water from private tankers. In the past year, INR 90,250 was spent to
buy 1332KL of water from tankers. There is a need to look at other options for
supplementing their needs.
Current functioning & Maintenance -
·
The school’s support staff do daily maintenance
and cleanliness of the terrace space and the filter. The terrace is cleaned
every 15 days, and the filter once every month.
·
The underground sump is cleaned every
3-4 months, through an external agency, which costs INR 5000 per cleaning. The
septic tank is also cleaned every 3-4 months, for a cost of INR 5000.
“It was my dream project to get the
Rainwater Harvesting system for the school and ensure that we are less
dependent on borewell and municipal water supply. While maintenance is the main
task, the RWH system has helped us be 50% sufficient so far”, says Mr Suriya
Narayana, Manager, Sisa Swiss-Indo Academy, Whitefield, Bangalore 560066.
