As-Built Question

Is the trench line still visible?

Give The Deposit Check Back

"As built" means where it actually lies, if they do not re-expose it, you cannot do the job.

For much more money there are precise probes to locate it vertically.

For much more money you can TV it and get linear distances to grade changes and bends.

Combined with probes at 100' intervals for grade and 5 probes 5' apart at change points you could do a credible job.

Problem is probing can destroy protective coating.

I think they hired you a few days too late.

Paul in PA

Dig it up.

Give The Deposit Check Back

Paden, not really.
Paul, wish I used that practice. (subject)

But these are my thoughts exactly.

Thanks from a long time lurker.
Now to let the contractor know.

I'd consider building a water powered hole digger. It would have HIGH pressure water, and a tube probe. So you could poke holes in the soil, (right above the pipe, in the backfill)
The high press and high volume of water would open holes, every 40' or so, and give you a pretty good idea of it all.

Of course, I'd charge for it.

But, somebody has to do it, right?

N

How deep is the pipe- will ground penetrating radar pick it up?

Give the client/owner options.
Perhaps the owner would be happy with a quick surface profile and the contractor's burial depth records... or not.
Potholes at 25' would be "best" but is it needed?
On a force main they really just need to know if there are high points for gas to collect in without a proper air release to let those bubbles out. In steep country it just does not happen, but the flat routes are a bugger.

Google "HydroVac" non invasive water jet potholing. http://www.badgerinc.com/ was one of the first hits and explains the process a bit. I used similar service providers a few times for design in sensitive urban locations, they can plug the 2 or 3 inch holes and leave almost no mark on the surface, or open it up enough to see the type and size of the conduit.

You did not create the problem, but you can help them come up with the "best" way to get the job done, for a fee.

Ditto, Hydrovac systems are the best way to go to be 100% certain what you are locating.

Count me as a third for hydrovac. Really, without the old trench available for you to know where to probe, that is the only feasible option costwise.

If the trench was available, I would do the probe method with random holes dug to verify the probe. (all of which would cost the client because of time).

I think I would turn down the job before I would go the dig up the whole line. But, depending on what the clients needs are, that may be more than they need.

Is this for the municipality, the engineer or whom? Talk to the people needing it. They may be able to give you a better option.

Those "water probes" are slick!

A force main is under pressure so it's grade is not as critical as a gravity based sewer system. Likely the line has been laid at a standard depth required for cover. In our area that is 36" and a tile probe can be used very easily.

Even if the line has been laid for months the ditch will be pretty easy to probe and follow. You should have a reasonable idea of the alignment but with a force main then they can have PI's in the line without employing a structure (SSMH) so you will have to be careful of the location.

I suppose the grades are important for engineering calcs on the performance of the line but that was all considered in the design. And if they maintained a true equal depth in the trench then possibly the surface profile will suffice for their query.

Just drop the line 36" or whatever their standard depth was and you will have a pretty good model of the line itself.

Deral