Marking location of new water line with RTK GPS

I’m getting ready to put down >2,000’ of 2" HDPE pipe on my property. In researching ways to be able to locate it years down the road, I discovered RTK GPS solutions that can pinpoint locations with great accuracy and that led me to Sparkfun. It seems like I could mark the pipe location, say, every 10’ after it is in the trench and before it is covered with dirt and I would have both location and depth information that could be saved for that inevitable time in the future where I’m trying to locate it. An alternative would be to just drop a tracer wire in the trench, but actual coordinates would allow me to visualize it on a map which I think would be of far greater value.

If I’m on the right track, would you recommend just buying the individual boards or the kits such as the Sparkfun RTK Express? Also, is there any reason to not purchase the new LG290P with its greater capabilities (and currently lower price) over the older ZED-F9P?

Thanks for your help.

Industry standard seems to be to just loosely wrap a wire around plastic pipes so that you can use a fox and hound type tracer to find the pipe later.

The units with included batteries are a bit easier to get going, but yes you could easily use the LG290P with portable usb-c battery pack and have a decent time with it

Instead of picking between the methods (GPS/trace), personally, I’d do both…that way you have a back-up plan for either

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Yes, that is how it has been traditionally done. With centimeter level GPS accuracy available/semi-affordable to non-surveyors now, it seems like maybe it is time to rethink that, or perhaps do both. I find it very frustrating that the other mile of pipe on the property (a 6" main water line and building to building fiber) are not marked in any way. I’d pay good money for a detailed map of where everything was run underground before we bought it. Bonus dollars if I could pinpoint it with high level accuracy.

That’s very possible with today’s tech. Most watermains (the 6" main you referenced) are installed with tracer wire and can be located (Horizonal and Depth) with good accuracy. It can be reasonably located without a tracer also. The Fiber can also be marked with a Underground Utility Locator.

BTW, What State are you located in ?

Do this even if you map it with GPS. Bury the wire 18" from the surface so it’s detectable if the water line is lower.

Regular GPS should be accurate enough to find a water line so don’t bother with RTK unless you need the precision for other uses.

Hi, it’s me, the equipment operator who buried the 6" main and fiber, posting from beyond the grave. I made a super good map at the time so we wouldn’t need tracers. Can’t you just refer to the copy I gave the owner back then?

Don’t even think about skipping tracers.

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Unfortunately, their was no tracer wire placed alongside the 6" water main. I’ve had to hand dig it up twice to deal with repair issues. The original installer did run a warning tape a foot or so above the pipe indicating what was below. I feel that the risk of breaking the line is to high to use a mini excavator to look for it. Fortunately the fire hydrants give a close approximation of where to start digging. And btw, a beefy rotary hammer and spade bit make “hand” digging in hard dirt far less arduous than it would otherwise be.

When Spectrum ran fiber Internet to our property (as opposed the the building-to-building private Intranet already on the property) last summer as part of the federal program that was put in place to bring internet to rural areas, they hired a guy that brought a ground penetrating sonar unit onto the property to try and locate the water main throughout the property. I spent hours working with him telling him what I knew about the approximate locations of the water main. His work definitely helped but it was never definitive and he could only approximate where he believed the pipe to be. It looks for patterns of previously-disturbed soil more than the pipe itself. I’m not aware of any other way to locate the main short of turning the water off upstream and removing a lateral connection saddle from the pipe to insert a sonde through the pipe that can be detected above. Is there another way that I am not aware of?

What location method were you referring to to find fiber optic lines underground without a tracer wire?

I’m located in East Tennessee, about an hour north of Chattanooga.

What would you estimate real real-world accuracy of a LG290P to be without RTK correction?

Can’t argue with that!

@David_Jensen - The LG290P has ~1m accurecy off the shelf with a good L1/L2/L5 antenna. The multi-bands help, but corrections and full RTK are really where these engines shine.

Several Active and Passive options shown here
Also, some folks have good luck with a “thumper” device, like this one for water lines.