Casing Pipes For Recharge Wells - Advice required : Coimbatore, Tamilnadu
Submitted by iwp on April 20, 2009 - 05:01
I am thinking of putting few borewells in my coconut farm near Coimbatore to store water (rain & released dam water) in order to increase the ground water level. Should I put PVC pipes are not? Kindly advice on the method I should follow to ensure maximum effectiveness.
Kindly write in with your suggestions and comments.
Saravanan
Comments
1.
Dear Saravanan,
Your question is not clear. Whatever the case or type of the casing pipe, the problem is same. How that bulging of the casing pipe is taking place.
The best solution is to call for a drilling machine and ask him to pull up the casing pipe, since it is only provided for up to 70 feet.
If it is an iron pipe, the pulling up process is easier. If it is a PVC pipe they will try to pull out the first part say up to about 40 feet and the remaining length will be pulverized into pieces. They will use higher capacity, wider bit for this.
Kindly install a MS casing pipe though it cost more to safe guard it against the bulging phenomena. Why it is bulging, where there any yielding zone encountered at this zone. Did the earlier drilling tried to block the same and went deeper down. Please use better quality pipe. May be some clay or highly sheared/fissured/fractured formation might occur at the zone and your pipe is unable to stand against the thrust pressure and hence it is bulging. If it is a yielding zone, then ask the driller to provide slots or tiny hole near the zone above one feet and below one feet to tap this water also.
Since at shallow zones the quality may not be up to the standard it is better to block this zone and move forward with blocking.
With best wishes,
A. Rajamohamed Ambalam
Geophysicist
Coastal Energy Private Limited
Chennai - 600006
2.
Dear Saravanan,
The size, depth and slot position of the casing pipe can be decided only after getting the information of the lithology of the area where the recharge well is to be constructed. Therefore, please provide us the details of the subsurface formation of the site and also the quality and quantity of source water. The subsurface formation can be ascertained by carrying out resistivity survey and the approximate formation can be inferred from the litholog of nearby bore wells.
However, for further information, you may contact me, or Dr.R.Raghuraman:
K.R.Gopinath – 09381043522
Dr.R.Raghuraman - 093821 60092
Regards,
K.R.Gopinath
Chairman
KRG RAINWATER FOUNDATION
Chennai – 600 102, Tamil Nadu
3.
Dear Sir,
I found my answer is misplaced into your query.
I shall explain first the kind of formation you get in around Coimbatore that supports recharge through borewells.
West of Coimbatore and north of Coimbatore has deep pediments and highly weathered formation occur. The thickness of such formation along the Siruvani road and along the Mettuppalayam road vary from 200 feet to about 100 feet. If you move along the Trichy road upto Sulur you get deep pediments and highly weathered formation upto about about 100 to 150 feet. In Thadagam road and Sanganoor belt we get valley fills and highly weathered formation. Along Avinashi road you get such phenomena upto about 15 kilometer and along Sathy road you get such phenomena till Annur.
Only along Palghat road and Pollachi road you meet hard weathered rock at shallow depth. And most of the land along this belt and along the Sulthanpet forms a catchment to Bharthpuzha river and doe not come under the Coimbatore phenomena.
Since you said the recharge of rain and dam water probably your land may in the pollachi, Kinathukadavu or Sulthanpet belt. Here you get hard weather rock at shallow depth and water level is also occur at shallow level due to recharge of the PAB system.
In this belt you can use PVC casing pipe. May be you can drill upto about 100 feet or 80 feet and allow the rain or dam water to enter into the bore. The bore pipe should be perforated or slotted. Except for the first legth, the other length can be slotted or perforated. Please dig chock pit surrounding these recharge bore wells may be for about 5 to 8 feet deep in a circular of rectangular of square manner. Fill the pit with sand, gravel and concrete chips and small stones in sequence. Guide the rainfall water through some digging, allow the filtered water to enter into the bore.
While drilling if the bore meet with some moisture or fracture then the recharge will be faster. Normally we find open wells are used during rainy days and during drought years deep bore wells are used. This recharge will supports recharge for your open wells and shallow bore wells.
If your aim is to get the benefit from deep bore wells then you should drill deep bore wellls put perforated casing pipe till the weathered rock and leave the formation below open. similarly construct chock pits.
You can approach SIRUTH"UKI at Coimbaore for further advice.
Wit kind regards,
A. Raja Mohamed
Geophysicist
Coastal Energy Private Limited.
Chennai. 600 006
bismi1234786@gmail.com 09443619352
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