RWH. Recharge Wells - Total Solutions Needed : Whitefield, Bangalore
Submitted by iwp on March 23, 2009 - 22:18
I live in a gated area which of 48 acres in Whitefield, Bangalore. We are completely dependent on Ground Water. So far , we have 2 borewells which are providing us with water for all purposes. We are a proactive community, where:
a. We have made RWH for every home mandatory.
b. Made Water Meters Mandatory to check the usage of Water amongst residents.
c. Implemented Ground Water Recharge [ wells] near the 2 borewells.
We find that the Well gets filled up in no time and it takes 24 hours+ for the well to dry up / soak into the ground soil .
We also have implemented a treatment plant to manage our Sewage water. I need guidance from experts , where in , we could recharge the Ground Water with the Treated Sewage Water. Our current Output is about 25K Litres of treated water every day.
We as a community are open for any suggestions, consultants are also welcome.
Naveen
Whitefield Bangalore
Comments
1.
Dear Naveen,
It is not advisable to recharge the treated waste water to the ground water. However, in the developed countries such experiments have been done. Such recharges are taken up with a concept of Aquifer Storage Recovery (ASR) and the area for such plan is separated from the common pool aquifer withdrawal.
With regards,
D. Chakraborty
Scientist
Central Ground Water Authority (CGWA)
New Delhi
2.
Dear Naveen,
Before expressing my views on the slow infiltration rate in your recharge wells, I need the following information:
1. What is the diameter of the recharge wells and their depths?
2. Is there any information about the soil lithology? Atleast upto 10 metres depth.
3. What is the area of the catchment for each of the wells? In other words, the size of the area, the rainwater falling on which is discharged into each of the wells?
4. When were these wells made? If they had been made more than a year back, have they been desilted atleast once?
5. What is being done about sullage?
6. What is the quality of the output water from the STP?
Best wishes,
Sekhar Raghavan, Director, Rain Centre, Chennai.
3.
As a water sector professional, my worst nightmare is that our over enthusiasm for Artificial Recharge has fouled up our aquifers too, like many rivers already are. In case of rivers, the monsoons provide an annual flushing. In case of aquifers, there is no such annual cleanup and a polluted aquifer stays polluted for a long, long time.
Unless you are treating sewage to a very high degree that can remove all the soaps and detergents that you use, as also various dissolved constituents of urine and night soil, all these substances will soon accumulate in your aquifer, and show up in your drinking water. Get ready to make Reverse Osmosis purifiers also mandatory.
Chetan Pandit
4.
Dear Sir,
You have 48 acres complex and all the residents are pro-active and made RWH in all the house and addition made recharge structures near the two bore wells.
It is some thing commendable and wonderful job. Please continue with that.
Kindly go through the materials published on this portal related to recharge of treated water.
I" very much appreciate your sense of recharge of ground water but do not think of recharging the ground water with your treated water what ever amount it is, even it is 100 K liters because it is not a pure water, it will have all the residue of the domestic waste in addition to chemical waste it has also bacterial element that will multiply many fold when it enters the ground water body.
Kindly use the treated water for gardening purpose and please construct some special drains and lead into some gutter or flood drain of the road.
If your society has some fund kindly drill recharge bore wells in groups close to your apartment groups and lead the RWH water directly into the bore well after constructing chock pit by following an appropriate design round the recharge bore well.
Please note that a successful recharge bore well is one that has successfully met the fractured or jointed aquifer that has considerable flow coming out while drilling. Do not convert the dry bore bore well as a recharge bore well.
By using couple of bore wells as recharge bore wells your can recharge the entire water in couple of hours. Since you have about 48 acres of land, You may be able to recharge, if we take just about 20% as your domicile area, then about 20 million liters of water, if only you meet with a fractures zones in your bore well.
I took the rational formula of recharge with just 20% factor. If you can have 5 meter dia and 3 m width chock pit around the bore wells then nearly 30 million liters per year you can recharge. You may kindly study the topography of the area and glide the RWH drain into the chock pit that surround the bore well by following the contours.
Please do not use the treated water for recharging the aquifer, this will pollute the water body.
This is for your kind purview.
WIth regards,
A. Raja Mohamed
Geophysicist
Coastal Energy Private Limited
Chennai- 600006
A. RAJAMOHAMED AMBALAM GEOPHYSICIST COASTAL ENERGY Pvt Ltd, CHENNAI +919443619352
5.
Dear Mr.Naveen,
I am a Water Management Consultant living in Bangalore.I would be willing to come and inspect your re-charge wells as well as your STP. I must commend your community for having done some good things like RWH, metering water supply to each home and treating your sewage.I would most certainly not recommend ground water recharge with treated sewage.
If you would like me to come and meet you and see your recharge wells,etc please call me on my mobile and fix up a convenient date and time.
Regards
S.S.Ranganathan
Mobile: 93437 34229
S.S.Ranganathan
6.
Dear Naveen,
You need to look at earlier answers given by learned members in this site and you will be better informed on the questions you have asked.
As regards your plan for recharging treated sewage water by your standards is a “no-go”. This has been clearly mentioned by many senior members before.
However when you find the STP- treated water as good as drinking water/ rain-water i.e to potable standards then you can consider it to be recharged to ground-aquifers which is very un-likely.
You can attempt to take the processed water 25kl say 25000 lits per day, can at best irrigate 10000 sqm of greens (apply a thumb rule of 2 lits per sqm per day ) which is around 2.5 acres only. This will be a relief on ground-water extraction.
Your 48 acres land would have greens atleast 30% say 15 acres- 60000 sqm which itself will require 120,000 lit i.e 120 kl per day.
Like other members have asked a few questions, some more:
1. How many homes do you have? What is your daily consumption ?
2. What arrangement you have for RWH in your areas?
With wellwishes from Vigyan Vijay,
Ajit Seshadri
ajit.seshadri@vigyanvijay.org
http://www.vigyanvijay.org
Er. Ajit Seshadri,Head- Environment, The Vigyan Vijay Foundation
7.
Dear Naveen,
Great idea to recharge gound water. It seems the design of recharge structure and calculations of permeability in white field do not match, that's why the water do not infiltrate faster. There are other ways to overcome this problem.
Addressing your queries , There are some special type of grass that absorbs most pollutants Search for "vettiver" in google. You may consider this technique before attempting recharging waste water. Apply this technique after complete study.
I live in Bangalore and would be pleased to help if needed
Raghu Subramaniam
8.
Dear Mr. Naveen.
A noble effort for a noble cause. I appreciate the effort.
You need to do a simple analysis and follow a few principles. May be do a brief study to arrive at estimates,
Water coming in (rain, ground water, other sources, treated sewage water etc) and water going out (Domestic and community usage, gardening, recharge, flowing out of the gated area, etc). Put them against each other and see the difference - solutions start becoming clear to you.
Do not forget to follow a few principles,
Ground water is common property and we cannot contaminate it (knowingly or unknowingly) - never inject raw water into aquifers directly or even after man made filters - always ensure that there is scope for natural infiltration and percolation - even while using bore-well recharge techniques
Conserve water to its last drop - reduce losses and assign water from different sources for different purposes.
Keep things simple for every house - maintenance of rwh systems and recharge structures - making things complicated leads to bad maintenance - technology used should be thus - or groups/community organised as such
Remember - you will not be able to use all the available excess water (100%) for recharge of ground water - you cannot...! - depends a lot on local geological conditions and how precise/scientific the efforts are - and consider that certain amount of water has to flow as surface flow - this is a natural rule
With best wishes
J K Setty
NRM consultant
Friends of Ecology and People
9.
Dear Naveen,
From your description of your layout and the questions you have placed I would like to respond to your question from a slightly bigger picture perspective.
At an overall level to manage water in a layout which is responsible for its own water supply, the following are the key aspects you have to consider:
a) Source managment (In your case ground water management) - Recharge of ground water using rainwater is of course the most obvious investment as a part of it. However, metering borewells keeping tab of its electricity and quantum of water yielding etc is necessary to understand how much you extract and can extract in the future. Recharge effectiveness is subject to local geological conditions. In Bangalore Recharge wells are found to recharge the water completely anywhere between 24 hrs to 72 hrs when recharge rates are relatively good.
b) Demand management : To ensure responsible use of water and reduced call on piped water supply from the unit (household level). Metering household consumption, pricing the water appropriately, ensuring every household in the layout does rooftop harvesting as a supplemental source of domestic water are some of the things you can implement. This should also include an education campaign for all the households. Beyond a certain demand, households should be made responsible for their own “import” of water.
c) Waste Water Management – among the toughest aspects of water management. Firstly there has to be a will to implement and operate the local STP (whatever kind) so that the output quality of water is as good as possible. The question of recharging this water can only be answered based on output water quality tests – only if BOD/COD levels, TDS levels and Nitrate/Phosphate levels are acceptable can it be considered for recharge. And these tests should not be one time tests but on a regular basis ensuring the STP is running. However prior to recharge of STP output water considering resue of STP water for purposes atleast for landscaping should be considered.
Finally while considering the tariffs for water the entire life cycle cost of water should be considered – not just sourcing and supply costs but also waste water treatment costs. Community taking ownership of this management end-to-end is critical to move towards sustainability.
Regards
Avinash
(avinash@biome-solutions.com)
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