Borewell Rehabilitation - Siting a new one - Help Needed! Bangalore

Dear Sir,

I am sorry to learn that the two bore wells in your premises / apartment went dry.  Your neighbours bore well are deeper around 800 feet. This might have come up about a couple of years back.  It looks that in your area the water yielding zone is much below than your both the bore wells level and you could not reach to that depth to tap the ground water as your neighbours had tapped.  you should also try to reach your neighbours depth level by either deepening your bore well or taking up a new one.

In Bangalore there are many consulting Hydro-geologist / firms who can assess and help you. You can contact AFPRO Field unit at Bangalore or Geoservices at Hyderabad who have deep probing equipment to assess the water availability or other wise at that of about 800 to 900 feet.  However being an inhabitant area and too in an apartment complex it is very difficult to spread the cable to conduct the resistivity investigation. However by conducting shallow spread studies and correlating their findings with the nearby drilled and successful bore wells they may be able to help you in finding a new spot for drilling bore well or to deepen the existing bore well.    

An experienced Hydro-geologist or Geophysicist is most advisable.  You can enquire with the local drillers or pump distributors and get a able consultant if you or unable to locate the above.

Further below I have pasted your queries and try to answer your doubts. 

Any techinical specifications that we need to ask from these vendors like:

1. Video testing: Are there different in types lke resolution?

   What for you are going to do the video testing.  Is it to find out water available in your bore well or based on the video graph are you going to obtain a new site for drilling bore well.

    Please note that video graph or camera test are useful only to ascertain the type of formation and sequences of the strata you encounter and in the water column also you can take the video to analyse and reassess the formation details.  It is used in problematic wells to find out the cracks and fractures and its depth so as to do ascertain the packer installation depths for hydro fracturing or blasting.

It is useful in solving some well construction problems where it will be difficult without the data of the strata structures.  As your bore wells are almost dry it will be of no use and hence I honestly feel that it is wasteful exercises and going to cost extra expenditure on you.

 
2. Hydro fracturing: Like max depth that can be treated; max water pressure,

       This is useful when the neighbouring area holds water and your bore went dry provided your bore well also had reached the same depth or more than that of your neighbours.  As your bore well have much lower depth level and it looks from the provided information that the water yielding zones are below your present bore well depth levels this is not going to provide you any positive result and hence it is not advisable.

3. Drilling: What type of drill m/c suitated for such deep digging.

This is a site specific one and normally in your area DTH rigs with high pressure capacity can negotiate up to the required depth.  There are bore well companies in Bangalore who have the deep drilling rigs and you can find one.  Also you can ask your neighbours and use the same type of rig in your case also. 

4. Casing type?

This is also site specific.  However what ever the depth level neighbours have provided the casing you can also provide and whatever the type of casing provided by your neighbour you can also adopt..  It is easy and you need not analyse the pros and cons, because a successful models of numerous events / bore wells are already established and follow the same model by logic. 
4. Any other information like making of chamber etc.?

       Whatever the system you have already adopted in earlier days same system may continue unless otherwise additionality is required.  In that case you have to sit with a water supply engineer and design a new one for you.

Further I would advise you to use the dry bore wells as recharge wells.  All the rain water that run off from your complex can be collected and guided and distributed to the two bore wells.   In the long run this will help your proposed new bore wells and your neighbouring bore wells to get prolonged water supply in dry season.  This will over the years will or can enhance the level of the general ground water table and the future generation will be thankful to your act.

With best of wishes,

A. Raja Mohamed Ambalam

Geophysicist

Coastal energy Pvt Ltd - Chennai.

bismi1234786@gmail.com; 09443619352