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Thread: Frustrating Water Line Locate

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    Default Frustrating Water Line Locate

    Trying to locate an 8" water line. Couple thousand feet. Points of contact are four hydrants, meter pit and service to building. Large sections of pipe will not locate. Much of the signal is ending up on power. I have connected at point with a ground rod to produce the circuit. Always get decent current on the circuit. I have used a direct connect where I run a signal line from the transmitter directly to a distant portion of the pipe. I end up with over .5 amps, but still cannot force the signal onto the pipe. The pipe has mechanical joints (gaskets and bolted flanges). I have used frequencies from 512 to 200 khz. No use. Have dropped box with limited success. The pipe is steel--it has been witness on prior excavations. Any tips? I am using a SeekTech SR60.

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    Conservative Meanie ifinditunderground's Avatar
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    Default Re: Frustrating Water Line Locate

    Familiar with double ended connections?
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    Mke
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    Default Re: Frustrating Water Line Locate

    Quote Originally Posted by ifinditunderground View Post
    Familiar with double ended connections?
    See, I would of gone with, "familiar with Metrotech 810 or Pipehorn?"

    mke
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    Default Re: Frustrating Water Line Locate

    Tried double end from meter pit to two different fire hydrants. Still ended up with most signal on power lilines.

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    Default Re: Frustrating Water Line Locate

    Use your witchin sticks man!

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    Default Re: Frustrating Water Line Locate

    Quote Originally Posted by testtech View Post
    Trying to locate an 8" water line. Couple thousand feet. Points of contact are four hydrants, meter pit and service to building. Large sections of pipe will not locate. Much of the signal is ending up on power. I have connected at point with a ground rod to produce the circuit. Always get decent current on the circuit. I have used a direct connect where I run a signal line from the transmitter directly to a distant portion of the pipe. I end up with over .5 amps, but still cannot force the signal onto the pipe. The pipe has mechanical joints (gaskets and bolted flanges). I have used frequencies from 512 to 200 khz. No use. Have dropped box with limited success. The pipe is steel--it has been witness on prior excavations. Any tips? I am using a SeekTech SR60.
    The variables you have to consider would be material, depth, and construction methods. If the valves don't have extensions on them, the depth may not be the issue. It then comes down to the other two. Material plays a big role, if it's an old transite line, you are officially hosed. Likewise, if it is PVC, C900, HDPE, And the like, none of it locates. If it's old enough, it could cast iron instead of ductle and the signal doesn't carry well if at all. If there was nothing else around it, you may be able to induce enough to connect the dots. Then comes construction methods. Certain mechanical joint require gaskets that will kill the best of signals. If you go back even further, they use to use a lead compound to join the pipes and this compound doesn't typically carry tones past the joint.

    I don't mean to keep tossing out reasons that it may not locate, but with your equipment, it doesn't lend itself to induction. If I had my 810, I would locate the electrical, then side box off of that to see if you can pick up a separate conductor. If you do, then I'd see if it lines up with the valves and hydrants.

    Mke
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    Default Re: Frustrating Water Line Locate

    Hi Mike: The facility people tell me it is steel. They recently did a repair on a leak. The depth tends to be around 6'. It does have mechanical joints with gaskets. This could be the main problem. However, these are bolted joints, so flanges on each pipe section are bolted together with steel bolts. This should provide an adequate signal path (although it may not, since I have limited evidence so far of following the pipe around a joint. I am curious about your comment concerning induction. IF the mechanical joints are preventing the signal from traveling on the pipe, induction will be the way to go. Induction in fact worked poorly on much of this pipe. When I induced over the power lines, it worked well. I am using a Seektech instrument for the receiver but a Radio Detection RD4000 transmitter. Next week I intend to try the Seektech Q33 transmitter, which, according to the manufacturer, provides a substantially stronger induction signal due to its unique coil design. We shall see, but if you have some insights that would suggest there is better suited instrumentation, I would certainly value your opinion. By the way, in some sections, there is gas and power in the same trench with the water line. This was the case at the excavation that was recently completed.

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    Mke
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    Default Re: Frustrating Water Line Locate

    Quote Originally Posted by testtech View Post
    Hi Mike: The facility people tell me it is steel. They recently did a repair on a leak. The depth tends to be around 6'. It does have mechanical joints with gaskets. This could be the main problem. However, these are bolted joints, so flanges on each pipe section are bolted together with steel bolts. This should provide an adequate signal path (although it may not, since I have limited evidence so far of following the pipe around a joint. I am curious about your comment concerning induction. IF the mechanical joints are preventing the signal from traveling on the pipe, induction will be the way to go. Induction in fact worked poorly on much of this pipe. When I induced over the power lines, it worked well. I am using a Seektech instrument for the receiver but a Radio Detection RD4000 transmitter. Next week I intend to try the Seektech Q33 transmitter, which, according to the manufacturer, provides a substantially stronger induction signal due to its unique coil design. We shall see, but if you have some insights that would suggest there is better suited instrumentation, I would certainly value your opinion. By the way, in some sections, there is gas and power in the same trench with the water line. This was the case at the excavation that was recently completed.
    Tech, part of the issue is the flanges that hold the bolts are cast iron. Between the signal distortion from the joint and lack of conduct able material make that joint difficult to jump. Even with a transmitter that induces good, if the joints are too close together, you may still have issues.

    How much separation did the guys say was between all the utilities?

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    Default Re: Frustrating Water Line Locate

    Is it possible to access the water line and run a fish tape? If it's potable water this isn't always an option but if you can run a fish, attach a heavy gauge wire to the tip and run it in. Ground the other end of the wire wire when the fish is fully extended to create a loop. You should get a great signal.

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    Mke
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    Default Re: Frustrating Water Line Locate

    Quote Originally Posted by daman1 View Post
    Is it possible to access the water line and run a fish tape? If it's potable water this isn't always an option but if you can run a fish, attach a heavy gauge wire to the tip and run it in. Ground the other end of the wire wire when the fish is fully extended to create a loop. You should get a great signal.
    Typically you won't get access to the line like that. You can, in theory, but you have to run chlorine through the line to cleanse it. As for pushing that kind of distance, you would want to use a rodder, preferably one that has a conductor inside.

    This is one of those locates that has no easy answer... You just have to try everything

    Mke

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    Default Re: Frustrating Water Line Locate

    Correct. No access, unfortunately. Mike, I suspect you are right about cast or ductile joints being the problem. I have experienced this before and without a good solution. I am going to try GPR next week. In my part of the world, it is rarely successful, but it is worth a shot. I will also try a different transmitter and see if more signal can be induced on the line. Maybe witching sticks are the way to go, as suggested above.

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    Default Re: Frustrating Water Line Locate

    Quote Originally Posted by testtech View Post
    Correct. No access, unfortunately. Mike, I suspect you are right about cast or ductile joints being the problem. I have experienced this before and without a good solution. I am going to try GPR next week. In my part of the world, it is rarely successful, but it is worth a shot. I will also try a different transmitter and see if more signal can be induced on the line. Maybe witching sticks are the way to go, as suggested above.
    Tech, you familiar with "side boxing"?

    It is one of those tricks you use depending on the situation. This sounds like one of those times. It may help, depending on the separation of the utilities.

    Mke

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    Default Re: Frustrating Water Line Locate

    Hi Mike: In the location that was excavated, the power was beneath the pipes. This power was a relatively small feed and ground wire. The presence of a ground wire beneath the water line would certainly send the signal where it is not wanted. In other areas, main utility power at 13kv probably runs in or near the water line trench. In other locations side boxing may work. Worth a try.

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    Default Re: Frustrating Water Line Locate

    I have wandered why if the line is full of water and pressurized you can't induce the water in the line. Water is a great conductor but I've tried it before with mixed results.

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    Default Re: Frustrating Water Line Locate

    Drinking water is actually a poor conductor add salt and it's a different story.
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