Packer/Lugeon testing

[mullen]

Hi I am working in the caucusus mountains conducting a site investigation for a hydro power project.
We are doing single packer tests at 5m intervals to inform grouting and other design issues for the dam. The consultant is inexperienced in this kind of testing as are we. They are insisting we pump up to 200l/min into the holes while not achieving pressure or at pressure as low as 0.1 bar this is destroying the formation and causing any sediment to mobilise and back fill the hole causing us to have to redrill each test section which is both time consuming and expensive. I would love to hear any comments on normal field expectations both on flow rate and pressures. Also is there a tolerance on pressure fluctuations it is almost impossible to stop needle deflection to less than 0.1 bar while using our bean pumps at this rate of flow.

 

[GeoPaveTraffic]

Packer tests are a lot more complicated to run than most people give them credit for. 200l/min is too much flow for proper testing.

Questions:

You indicate that the tests are being ran at 5m intervals. Does this mean you are testing 5m of borehole with each test? If so, first thing is to reduce the lengt of each test.

Second, you say you are using 0.1 bar, it that at the top of the borehole? Are you correcting your pressure for flow losses?

Are you correcting for the natural groundwater condition in the area?

What kind of rock is the formation?

Once you respond with some additional information, we may be able to give you some additional information.

Mike Lambert