Tracing Laterals Underground

You have made attempt to contact the installer or checked the schematic? The one with writing all over it?

You may need to make a decision that it will be immediate to the valve location.

The installer is not known. There is no schematic or diagram of the system.

If I understand your question correctly, then..

--if the common ground is broken, then you can use the other wire to send a signal on, no?

--if both are open, then end of signal = break point

--if break point is encountered, then dig up both ends, and repair it, to continue tracing to find valve.

--if you can find the valve, but can't find the open, a Fault Finder would be able to pin-point the exact location, then you can dig up the break and repair.

--I used to use 3M coating/sealer/rubber to prevent underground splices from corroding.

Well, the question was for identifying where a lateral is.

I traced both wires and they both led me far beyond the area where valve is located. I know the valve is within an area of 5,000 sq ft. The valve box has a lid 6" in diameter and have tried probing the ground to find it (assuming its not buried more than 5 inches).

I think I'm getting some sort of signal hopping with the other wires in the bundle.

Ok,

..it may be possible to short out the other wires, to try and cancel the signal hopping.

..also, your lost valve may be inline with your signal path, and therefore have no lateral.

..an alternative is to keep the irrigation lines filled with water, isolate them from the source, and utilize the water in the pvc pipes as a conductor, to send the signal on..

..of course, if your a dowser, you've probably already found your lateral and valve, and your just testing us.

Thanks for the posts pj

I'm very interested in the comment about using the water as a conductor for the signal. Would I just use the inductive pipe clamp that came with the wire finder? The user's manual never mentioned that as an option - but would be greatly beneficial if it works. I could map all the pipes with flags and follow to the origin.

The photo isn't of the one I have, but you get the picture.

This particular valve must tee off the trunk. There are 2 other zones past it. The valves placement could be just inches from the trunk, but when I was stabbing at the ground with a screwdriver, I would check the immediate left and right as well.

Well, I'm going to google "inducing signals water".

Thanks again for the ideas

AZ,

- If each valve is controlled separately, you should be able to use your wire finder trace each switched wire from the controller all the way to its valve, including along its lateral.

- Can you trace the pipe connected to the valve? Your wire finder might work on metal pipes as well. If the pipe is non-metallic, and you can open/drain it, shove a metal fish tape (or a fiberglass fish tape with a wire attached) down the pipe and trace the tape/wire.

- If neither of those options are viable, you might be able to use a metal detector to locate the steel armature in the solenoid. It's usually a pretty safe bet that the lateral will be the shortest distance from the valve to the main run.

Good luck,

P2P

Yes they are controlled separately, but the signal is continuing past the valve in question. The system is probably 15-20 yrs old and if I'm not mistaken a lot of contractors here, back then, would connect both ends of the colored wire with the valve's solenoid wire, making the signal not drop off.

The tracer could induce the signal on a pipe, but unfortunately, it's poly pipe.

We have a method for this, but is time consuming and not overly efficient. What we've done before was dig near a sprinkler head, find the pipe, then move 3-5 ft, dig again...etc If we come to a tee, cut the pipe figure out water flow direction and continue previous steps until valve is found.

I like the fish idea, but I think it would prove difficult as each zone of the sprinkler system could have many tee's and 90 deg. turns to explore.

I'll have to google metal detectors to see what's available nowadays. One specifically for copper would be nice.

Thank you for the help

I'm thinking air could be introduced into the piping and with the water an acoustic surface listening device may enable detection of the poly pipe. If you knew the acoustic changes caused at the valves or I don't recall a pipe size noted to make use of an un-tethered leak detection tool.

That has actually worked for me before (not when anything was broken though). We winterize the systems with a 6 cylinder air compressor, and I'd say 15% of the time, I can hear a bit of a whistle/hum as the air passes through a valve.

The only problem in this case is that the valve is not operable.

The pipe sizes vary - the trunk is usually 1"-1.5", after the valves it is almost never larger than 1", then it gets reduced to 3/8" right before the sprinkler heads.

Is there a mathematical formula to find the "magic" pressure/cfm combination to create a whistle at the valves?