We have been approached by multiple gas companies to perform as-built surveys of their pipelines. Unfortunately, most of the pipelines are already back-filled.
I've used my Schonstedt in the past to detect steel lines. While this method is not exact, it was good enough for my purposes at the time (rough location on a boundary plat). I have little other experience in this regard.
There are more specialized pipeline locating devices. Does anyone have experience/advice? Note: some of the pipelines are poly, with a tracer wire above the pipe. Some are steel.
I use these guys
www.mps3d.com
Radio detection with a transmitter is the way to go.
The RD 7000+ and 8000+ are real good. We still have a few RD4000 that we use. I have gotten over a mile w/a good clean connection.
The key is to not have a lot of other lines that the signal can bleed off to.
http://www.radiodetection.com/products.asp?sec_id=2689
But we all have our favorites and we usually have more that one type of locator in the truck.
Do you
have to provide vertical also? If so be sure to buld in enough to probe and/or post hole to get the depths. I agree with the others about using direct hookup to trace the pipe (tracer wire). You get better results and longer distances. Be careful if there are two or more pipes in close proximity, you can get "bogus" results if you're not careful.
Andy
Do you
also be aware that you probably do not want to probe any non metallic lines. Most clients will not even let you bring a probe on job site.
Should have stated that you can get a depth (approx.) reading with most Radio detection systems.
I've always had the client flag any backfilled trench when it's not evident (fresh trench) where the line is at.
Can't remember a time any one of them wouldn't.
We (Wiser Company) offer 3D subsurface mapping using ground penetrating radar (GPR). Its effectiveness depends on soil conditions, however the NE typically has very good conditions for GPR. Let me know if you would be interested in a teaming arrangement.
Justin Rains
Did 85 miles, of gas line. The line had been put in about 20 years prior in range land, irrigation turned it into farm land, the gas company wanted to put more pressure in the pipe and a minimum depth was required. We located the depth every 25 feet, that distance was paced. We used a metro-tech with the emitter attached to the trace wire to locate the pipe and obtain the cover depth, if it was less than the specified depth, it was probed, 95% ended up being probed.
How I set it up was to get a bunch of those price tags, 1" in diameter with a sticky back and sent a crew ahead locating the pipe and leaving a tag with the depth written on it where the pipe was located and probed. Followed them with a total station crew obtaining horizontal location and carried trig levels ahead for the ground elevations. The shots were taken at the tag locations and the depth was read from it and entered in the field book and data collector and the data collector was downloaded to 2 disks each night, one was mailed in and I kept the other along with the field notes. Worked well, a 4 wheeler would have helped retrieve the emitters but we had two and I did a lot of walking, moving them ahead so the crews didn't have to stop to do it themselves. Probably better ways to do it now but it would be hard to improve on the measuring crew leaving the tags along the route for the other crew to use. Having never done this before, I told the crew that if they saw a better and quicker way and did not tell me, I would be mad about it, never had much problem listening to others ideas and I wanted them to be pardners, not subjects.
jud
Get a RadioDetection 4000. Hook to the pipe and locate away. Then, as-built the pipelines in some grid format. In Texas, they require "T4" maps, which are the as-built drawing but they have to be in some odd format and on quad sheets
A large portion of my work is pipeline and we use these:
http://www.ssilocators.com/pipe-and-cable-locators/pipe-and-cable-locator-2000.php
We use one of these to probe the first 1.5'-2'.
http://www.caturner.com/Bang%20Bar.htm
If I have a stake in the field with a cover it has been probed to determine depth. Over the last few years we have added several new clients because their surveyors at the time were relying on their instruments to determine depth and it turned out to be wrong.
I use 2 bent copper rods and witch for the pipe.
Ice
We've used these units to track hundreds of miles of gaslines. Pretty dependable if properly maintained.