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Thread: New Task...

  1. #1
    Mke
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    Default New Task...

    So I was asked to verify a waterline.

    Sounds simple enough. This waterline feeds a 2" hosebib. From this hosebib it runs through a broken valve (Hence the issue) through a fenced area that I have no access to, and can't get access to, then into a building where it goes up to the rafters and runs 150', then comes down to a Backflow preventer in the wall. In this wall is the only access point, other then the valve and hosebib outside. Between the hosebib and the building is a very large Industrial generator and a Light rail station with all the trimmings. This area is all concrete with multiple vaults of various utilities including other water lines that are not connected.

    The maintenance man stated they are not able to repair the broken valve untill it can be verified that the line is fed to the backflow preventor inside the building. All he is looking for is a way to verify that this valve is connected to that line.

    I love my 810, but by the time I get out of the building that signal is equal strength on 3 different spots. I hooked up in the hose bib and the valve, but it imediately goes into the enclosure where the large generator is and has a large grounding grid which plays hell with the signal because on the opposite side leads me to the same spots as the other hookup, and all about the same signal strength.

    And no, I can't go into the Generator area. And no, I can' not get another hookup point other then where the back flow is.

    It is assumed to be an entire copper line, but could have a transition to PVC that is not known.


    Would any of your guys' equipment be able to pin point that location given all the obstacles in the way?

    Thanks for any info.

    Mke

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    Member montecarloss's Avatar
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    Default Re: New Task...

    Shut the water off to the backflow preventer, no water at the hose bibb than problem solved!

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    Mke
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    Default Re: New Task...

    the sub surface valve, right before the hose bib is broken in the "Off" position. With the back flow off or on, it doesn't matter, no water to the hose bib.

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    Senior Member Turk182's Avatar
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    Default Re: New Task...

    Hook up a transmitter at both ends.

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    Conservative Meanie ifinditunderground's Avatar
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    Default Re: New Task...

    Quote Originally Posted by Turk182 View Post
    Hook up a transmitter at both ends.
    No, grounding one end or the other is the preferred method, even if you have to make an extended ground with a spool of wire with clips soldered on the ends. Ground it outside of the building as far from the generator and other utility interferences as you can. Use lower frequencies (less than 33k if possible) with higher wattage. I am learning the Mclaughlin G2 Verifier is excellent for this type of thing. Reverse your hookup/ground for verification. That really is all you can do. Besides a Pipehorn **(Model 100A @480 kHz)**, the 810 is the least desirable instrument for this scenario. Almost any instrument will do better. If I am not clear enough send me a pm.
    Last edited by ifinditunderground; October 2nd, 2012 at 12:37 PM. Reason: Edited for clarity
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    Mke
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    Default Re: New Task...

    so..... about that ground..... that probably aint going to happen. the nearest patch of dirt, besides the balast rock for the light rail, is about...... 400' away. Give or take 50'. Its accross the main road way as well.

    Ifind it, Thats exactly what I was thinking, its just the lack of grounding i'm kinda concerned with. I know the limits of my 810, but not sure how tempermental the other locators are with a crappy ground.

    Mke

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    Conservative Meanie ifinditunderground's Avatar
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    Default Re: New Task...

    If the ballast is not sitting on concrete, it'll have dirt under it......might need a much longer ground rod, but that shouldn't be too hard to get your hands on.
    There is a fine line between "Hobby" and "Mental Illness."
    "America isn't free, in America you are free to follow the rules." -Anthony Cumia


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    Senior Member Turk182's Avatar
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    Default Re: New Task...

    Quote Originally Posted by Mke View Post
    so..... about that ground..... that probably aint going to happen. the nearest patch of dirt, besides the balast rock for the light rail, is about...... 400' away. Give or take 50'. Its accross the main road way as well.

    Ifind it, Thats exactly what I was thinking, its just the lack of grounding i'm kinda concerned with. I know the limits of my 810, but not sure how tempermental the other locators are with a crappy ground.

    Mke
    A Hilti TE-16 with a 3/8" bit 36" long would solve your grounding issue.

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    Default Re: New Task...

    If you know how,Try witching it.Might get you close ,then set down your box and try inducing.Just a thought....

  10. #10
    Conservative Meanie ifinditunderground's Avatar
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    Default Re: New Task...

    Get anywhere yet Mke?
    There is a fine line between "Hobby" and "Mental Illness."
    "America isn't free, in America you are free to follow the rules." -Anthony Cumia


  11. #11
    Mke
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    Default Re: New Task...

    Not Yet, I got shat upon with other work, it looks like it will be Monday before I get a chance to wrestle with it one more time.

    I'll update the board when it happens.

    Mke

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    Senior Member daman1's Avatar
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    Default Re: New Task...

    Quote Originally Posted by Mke View Post
    so..... about that ground..... that probably aint going to happen. the nearest patch of dirt, besides the balast rock for the light rail, is about...... 400' away. Give or take 50'. Its accross the main road way as well.

    Ifind it, Thats exactly what I was thinking, its just the lack of grounding i'm kinda concerned with. I know the limits of my 810, but not sure how tempermental the other locators are with a crappy ground.

    Mke
    Depending on how thick the pavement is, you can drill a long masonry bit through the slab and sub grade in a discreet place and then use the bit for a ground rod.

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    Senior Member yahoo's Avatar
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    Default Re: New Task...

    I think bleed-off is going to be inevitable even if you could get a perfect ground as Daman has suggested ......there's to many paths of (least resistance ) as we like to say in the locating world ???? there's no way to get a perfect closed circuit ???? oohhh I think I have confused myself .....lol !!!!
    wise men talk because they have something to say and fools because they have to say something....plato

  14. #14
    Mke
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    Default Re: New Task...

    Yahoo, Thats kinda what i'm thinking. I'd love to drill random holes through the concrete (asphalt is in the roadway) but there is no way to covertly do that infront of the Police parking area at an international airport. I still would be hesitant anyway due to the grounding mat near the generator building. The mat alone is 40'x60' on the side of the generator building where this valve is.

    Thanks for all the input guys.

    mke

  15. #15
    Senior Member daman1's Avatar
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    Default Re: New Task...

    Oh yeah, 4got you worked at an airport. I was thinking of parking lot slabs or driveways. It's been done before.

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