gpr-forum.com

Profile showing a water leakage in a dam.
Equipment: SIR-3000 , Subecho-70 (2 units in bistatic mode), TR-501 (transceiver used as receiver), VHT-501 (Very high power transmitter).
Banner print: GPRSoft PRO
Location: Northern Sweden

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Reinaldo Alvarez Cabrera
Geoscanners AB
Sweden
http://www.geoscanners.com

Hi Geoadmin!
I'm not very familiar with this but I don't see anything specific except a "zone" around 100ns between 720-890m. Is that the leakage?
BR

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"If the only tool you have is a hammer, you will see every problem as a nail."

Hi bekic,
I didn't do this survey myself, but got the PDF from a customer who did it. I didn't have the opportunity to edit and make it a be more didactic.
Anyway, the leakage is around 15 - 16 meters depth in the profile and in the following locations: 620, 680, 725, 840, 880 ... and so on, you get the point.
You can see the strong reflections from the water. The people from the company that hired my customer said they were loosing about 100 litres of water per second. They are going to inject something called betonit plus cement to fill up the holes.
Best regards,

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Reinaldo Alvarez Cabrera
Geoscanners AB
Sweden
http://www.geoscanners.com

Hi GeoAdmin,
well, I think that it would be nice if you could get someone from the customers team to elaborate the findings/survey themselves , because I'm personally very interested in this kind of survey but from prior encounters with water leakages I've never seen the water leakages forming proper hyperbolas in the data (water tends to find a week spot in the concrete (or any other material) and then saturates a large chunk of material around it - more like a "zone" then a line object), allthough it could be some part of the construction flaw (iron reinforcement, drainage canals for the drying out the concrete in the damn....).
Perhaps I'm just wrong on this subject ,but I'm willing to learn.
As for the usage of bentonit it is quite common, and perhaps a good choice for this kind of job, but there are some other stuff they could use as well (BASF has some nice water reactive foams.....) - so I guess I could chit chat even on that subject, but I doubt it would be very interesting to the GPR comunity
BR

_________________
"If the only tool you have is a hammer, you will see every problem as a nail."

Hi Bekic,
I already put all the info I got from them, the next step is when they will survey the dam again after the owners have remediated the leakage as they explained. I hope there will be a follow up. I suppose the hyperbolas are due to the high amount of water leaking through what I imagine would be sort of a cavity or conduit. The only thing I left out was a story about the native people cursing the dam because it was built in one of their sacred sites. Apparently they told to the dam owners that the thing would never work and that "the spirits" will make sure it will be out of operation, that is "leaking". I dind't and still don't think this is relevant information, but just a curious thing I suppose. As hard as it might seem to believe there are native people in Sweden that are not Swedes.

The water leakage that I personally have surveyed in the past look exactly as you describe, "a zone of saturated material", please look here:
viewtopic.php?f=33&t=1601
I don't really know what happened there and the owner of the dam won't give more details to my customer neither, they just wanted to find where the damn thing was leaking. Apparently the results they got from my customer are in accordance to what they thought from the start since they were satisfied.

On your note about concrete, I have never heard of anything called betonit before this time so I don't think it would be boring or unnecessary for you to tell. It is always interesting to know how the damages we find can be mended, perhaps to give some ideas to the people hiring us.
My best regards,

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Reinaldo Alvarez Cabrera
Geoscanners AB
Sweden
http://www.geoscanners.com

Hi GeoAdmin,
my reluctance on adding more info on hydro-isolation solutions is based on a fact it doesn't have much to do with GPR - perhaps it should fall into everything else section?
However, one of the main things our company does is concerned with high/low pressure injecting of materials and other procedures for reconstructing/recovering/healing of the construction elements (walls, floors, roofing etc...) so if there is some interest on this subject here are a few earlier remarked solutions for pluging the holes in the damn..... and everything else:
http://www.basf-cc.co.nz/en/products/SolutionsforMining/Injection/Polyurethane/MeycoMP355A3/Documents/Meyco_MP355A3_TDS.pdf foam
http://www.volteco.com/hr/prodotti.asp?prod=Volgrip+LH_1 one application of bentonite (more common then the above insitu mixing)
BR

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"If the only tool you have is a hammer, you will see every problem as a nail."

really?! really, really?!
jd

Hi jd,
That's what I was told and for such big dams is not that surprising if you take into consideration all the leakages together.
Regards,

_________________
Reinaldo Alvarez Cabrera
Geoscanners AB
Sweden
http://www.geoscanners.com