Pipe and cable location

Ran 85 miles of gas line at 25' intervals locating horizontal position, elevation of ground and depth of cover using a Metrotech and probe. There are tools for what you want to do, but continue to do what you are now doing, research. The options, the effectiveness and reliability of the tools available is what you need to know, what I used is very old technology.
jud

We purchased a private utility locating company early this year and do only private locates. The more I observe the happier I am that our locators have 25+ years each experience at it. I have seen the local OneCall guys mark a telephone line as a major electric line which was 15' away. Our guys say they can train someone to be adequate in 6 months and expert in 5 years. It scares me more liability wise than surveying does for sure. Of course now we have no argument over who screwed up if it happens. I also know other surveyors that do locations of gas pipelines without much concern.

Nate, think like a broker, and sub the work to a professional SUE Company, and mark up their work 15%. You could do the locates after they mark the utilities. It could also lead to some work on other projects for them, in your area.

Identifying the location of many underground facilities -- particularly electric or telecom -- is beyond my level of expertise and equipment on hand. The two times I've been asked to map private underground line locations that weren't manhole-to-manhole or valve-to-valve, I hired a subsurface location firm to do the markout, then mapped the marks they provided. Cost depends on the availability of construction or as-built documents, site size, complexity and location. I spent $500 on one job, $1,200 on another. It was money well spent.

I just want to add that I have seen amazing differences in the quality of designation work done by different individuals. To do it competently requires some time of experience as well as having a certain knack for it.

I will relate that one time I called upon an individual who had been in business doing it for many years. This person designated a "marked water line" along the road for a distance. Upon inspection by me it was painfully obvious that the "marked water line" was in fact where a truck had run over a splotch of blue paint and then had simply driven down the road leaving paint marks as it went. I dug up records from the water department that showed the actual line as being in the grass behind a sidewalk.

Choose wisely.

Stephen

50% of my work is locating lines. This is not something you want to do without someone experienced. If the lines are made of PVC and no tracer wire you may not be able to locate them with any type of equipment. The only way is to probe them which often can be time consuming and frustrating. As suggested above sub out the work to someone who does this on a regular basis.

When I first got out of university one of my first field jobs was to survey the inside of the Oregon State Pen or as we came to know it, the Old Surveyors Home. Since access was limited, we had to do our own locates. We had what at the time was the latest technology but ended up witching for the waterlines with welding rods. Oran, my chief for the job, had learned the technique while surveying the City of Portland’s wooden transmission lines from the mountains. I was amazed how well it worked.

That being said, in my own business I would not take on the liability. Leave it to the pros.

I have called a plumber, that owns one. He said that:

Locating an electrical line is very easy.

Locating a water or sewer line, with a tracer line, is easy.

Locating a metal or cast iron line is easy.

BUT, locating a deep sewer line, the is PVC or a small water line, that is PVC without a tracer, is hard. Very hard. Iffy.

So, for my project,

Knowing where the electrical is, is important.

I'd like to try it.

Nate

Nate

I say go for it. If your in the big city, then they have a specialist that does everything for them. I hear tell they even hire electricians to change light bulbs and chefs cook their dinners for them! Our here in the sticks, we even do our own surgery.

I agree with the advice of hiring a firm that does pipe and cable location. They have the experience, and you can be confident while avoiding liability. If you were locating pipes/cables on a daily basis then you should consider buying your own equipment, learning as much as you can getting as much experience as you can. I never recommend to someone to locate utilities using new equipment and then peoples lives are on the line when it comes to high voltage utilities, etc. We sell pipe and cable locators at EngineerSupply.com if you want to see what new equipment costs. It's usually customers like city departments that have owned locating equipment in the past, or they have a daily need for locating so they decide to buy their own equipment. Even then, they should learn to locate over time, and still outsource to qualified/experienced locating firms for any voltage or potentially dangerous lines, at least until their in-house staff gains the necessary experience. Even with the equipment, utility location is based on years of experience, knowing when to recognize dangers, or situations that require utilizing multiple frequencies, and methods that give the best estimation of where a line is at. Remember, utility location is an estimation, it can be nearly exact at times, but its like looking at an as-built drawing, it shows where something is "supposed" to be. Hope this helps.

About 10 years ago the nearby university campus generally relied upon its in-house GIS to keep track of underground lines. As was customary at the time, whenever I did a topo I would show the GIS locations of lines I wasn't able to substantiate from surface observations. On one such project -- a topo for large new science lab -- there were a couple of 20" chilled water lines crossing the site. Unfortunately, they were about 140' from the GIS location, and an excavator found them the hard way. Ever since "the lake incident," the university potholes critical utilities as part of the pre-design topo. That way they get reliable horizontal and vertical position, with size/type verification as a bonus.

I got a task in Nevada County which involved finding and surveying the water line (3" steel) from the spring on USDA-FS property to our Fire Station. No one knew exactly where it is located. They built it in the 1950s but no effort was made to map it accurately. They thought it only crossed one private property (between the Station and the FS boundary) but I found that it crosses two private properties.

We have a no scale sketch in the file which is sort of schematically correct but misleading too. It has the Section line several hundred feet south of its actual location. This is why there is an extra private property we crossed. Someone assumed that they only needed to get rights from one owner, not two.

We followed it with a Schoenstedt cable locator that I borrowed from our Engineers. I also potholed it occasionally to assure myself that the locator wasn't lying to me. We also clamped onto the actual pipe (down about 12" to 18") to induce the current into it. We could follow it for about 500' before the signal got too weak.

Using locating equipment is an art; you need to have some idea where the pipe or cable is and roughly what direction it runs.

Liability

Beware if you think you are removing yourself from liability if the locator you hire screws up. What will happen is that you will be sued and your recourse is to sue the locator (subcontractor). The better way is to recommend the customer hire a locator and then you locate their marks. Forget about the 15% mark up - it's not worth the liability.

Liability

I trust myself with the final outcome on this case better than hiring any location service. I already know where the elec service comes out of the ground, and where it goes in, and it is under for less than 300', AND I think it is fairly straight line betweeen.

I trust myself better than some of the "in a hurry" dudes, I have SEEN in the one call truck. I have SEEN their work.

Best would be to let the client hire one call, but, I can take my time, study it, and, I have some buried lines, the I already KNOW where they are, to practice on.

I feel that I can do as good, or better in the final location, than a green one call fellow.

NOT as good as a well experienced on call guy, but this will work.

N

Liability

I guess I am saying that I agree with SURVEYLTD, above, about the liability... that is, if I sub it, and add 15%, then I am in the liability chain, AND may be the victim of a junior pipe and cable worker. I'd druther do it myself than that. BUT, best would be to either hire somebody who is a true expert at it, or let my client hire him.

So, I have found what I think is a good deal on a used Pipe and Cable locator, and may try it. I have done alot of things.... and succeded!

N

Nate, if you insist on going old school...

> So, I have found what I think is a good deal on a used Pipe and Cable locator, and may try it. I have done alot of things.... and succeded!

I have rented these things from the local contractor grade rent-it center for about $50 about a day.

Having used one, I can assure you that they work great on buried conductors. Don't waste your time with non-conductors. Carefully handled, you can pretty much pinpoint the location and even make a pretty good estimate of depth.

At a distance from the conductor you will be getting a "background" tone. As you approach the conductor (perpendicular to the path of the conductor) the tone will "trough" at some distance from the conductor, then peak when right over the conductor. That distance from peak to trough is the depth to the conductor.

Thanks, Mark.

I don't think that it would take me long to learn... with the tracer wire.

N