Difficulty locating concrete sewer

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GPRuruguay
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Difficulty locating concrete sewer

Post by GPRuruguay »

Hey everybody I own a SIR-3000 and a 400 and 900 mhz antenna.

I took it out the other day to locate a section of concrete sewer that had collapsed.

I found voids but couldn´t locate any section of the sewer line that was intact, even scanning right over it.

In the image attached, the green linre represents where the pipe should be at 1.65 m deep, but nothing...

Any ideas?
Screenshot - 23_07_2015 , 10_51_33 p.m..jpg

nsm
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Re: Difficulty locating concrete sewer

Post by nsm »

The properties of the concrete and the host soils might be very similar, so you can not see the concrete pipe itself. If this is the case, you are actually looking at voids (the air space inside the concrete sewer). If the sewer pipe is not big in diameter, you probably can't see it clearly in GPR profiles. How big is the pipe and what kind of soils do you have there?

GPRuruguay
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Re: Difficulty locating concrete sewer

Post by GPRuruguay »

The pipe is ovoid shaped, about 90cm in diameter and 1.2 m tall. The top of the pipe is at 1.65m and the green dotted line was made at the center of the pipe.

I can send you the .dzt files if you´d like :)
Attachments
20150723_140824.jpg

Simon
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Re: Difficulty locating concrete sewer

Post by Simon »

You can upload the dzt file as an attachment so we can all take a look. :D Thanks.

GPRuruguay
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Re: Difficulty locating concrete sewer

Post by GPRuruguay »

There are the files. These scans were done over a section of the pipe that we know is in good condition. I also have files for the sections where the pipe is collapsed.

Thanks for looking at this.

I´m going to try a different gain profile callibration next week.
Attachments

[The extension dzt has been deactivated and can no longer be displayed.]

[The extension dzt has been deactivated and can no longer be displayed.]

[The extension dzt has been deactivated and can no longer be displayed.]


Rauf
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Re: Difficulty locating concrete sewer

Post by Rauf »

Dear GPRuruguay,

You have distorted your data by applying wrong IIR vertical filters. Since you collected your data by using the 400 MHz antenna, so you need to setup your filters as 800 for the low pass and 100 for the high pass filters. We need to pass at least the 400 frequency because this is the frequency that we are generating and sending into the subsurface when we use the 400 MHz antenna.

Best wishes,
Rauf

Simon
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Re: Difficulty locating concrete sewer

Post by Simon »

Rauf wrote:Dear GPRuruguay,

You have distorted your data by applying wrong IIR vertical filters. Since you collected your data by using the 400 MHz antenna, so you need to setup your filters as 800 for the low pass and 100 for the high pass filters. We need to pass at least the 400 frequency because this is the frequency that we are generating and sending into the subsurface when we use the 400 MHz antenna.

Best wishes,
Rauf
I never thought this could happen. GPRuruguay, what frequency filter did you apply while collecting data?

GPRuruguay
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Re: Difficulty locating concrete sewer

Post by GPRuruguay »

Well apparently you don´t have that option in the SIR-3000.

gmradar
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Re: Difficulty locating concrete sewer

Post by gmradar »

You can easily apply filters with your SIR-3000. People above are right; you have to set 800-100 frequency window for the 400MHz. If you can find how to do it, go to recall setup and recall 400MHz antenna
Geomorph Instruments,
Your reliable Geo Supplier
https://www.gmradar.com/#/

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