Sealing of Piezometers in boreholes

[BigH]

I was wondering if anyone has seen a really good article, book chapter, etc. on how to choose locations for sealing piezometers (or standpipes) and the like. I don't remember seeing anything geared to the practical. I've seen, years ago a bentonite seal put into a sand layer - what is it going to seal?

Cheers

 

[BigHarvey]

If it is a standpipe type of piezometer, unless you have several levels of water, or want to monitor the behaviour of a clay layer during ground improvement, there is no interest in using bentonite seals.

The purpose of a bentonite steal is to reinstate the continuity of an impervious layer ( caused by the borehole ). Installing a bentonite seal in a sand layer is an irish joke ! The water will flow around the seaal in the sand.

I I remember having seen some kind of procedures ( but did not check ) on the Slope Indicator Company website.

 

[BigH]

I agree BigHarvey - the reason for the question. I was just wondering where "newbies" learn about sealing piezometers, when to do, etc. I just saw an installation where they put an expensive casagrande piezometer tip in a hole and then put 7 m of perforated pipe above it. If they are using a perforated pipe and not sealing the casagrande tip - why use the casagrande tip at all? In consolidating clay layers, you might want to measure the water level at various depths - in layered sands and clays, you want to seal standpipes in the two sand layers - but seal off the two from each other. - but, yet, time and time again, I am sure that many just don't know . . .

 

[dgillette]

Here's one possibility, provided you aren't still using dial-up (about 36 M bytes):

http://www.usbr.gov/pmts/instrumentation/policies/EDamInst.pdf

and another, although it's not real long on detail:

http://140.194.76.129/publications/eng-manuals/em1110-2-1908/toc.htm

Also, an oldy but goody:

Hanna, T.H. (1973), Foundation Instrumentation, Trans Tech Publications. (This is 1st edition; don't know whether there is a newer one.)

Best regards,
Dave