Detection of Pipe after Microtunneling 3

[supersuk]

Hello all,

The concept of deep tunneling is new to me and have a question regarding detection of the pipe after construction.

Right now i'm designing a deep (-45 to -50 feet deep) sewer collection system which will be under bodies of water and land. My question is: after the sewer pipe is constructed, are there techniques that could be used to easily detect the pipe years down the road other than using asbuilts, such as wire tracing (provided that we install it during construction), radar, etc? Our client doesn't want to only have to depend on the asbuilts. Which of the suggested techniques will provide the most accurate results?

The pipe must be detectable due to future expansion of bridges that it will cross.

Thanks in advance!!

 

[LittleWheels]

What is the pipe material and ground conditions? Non-destructive detection of pipes (e.g. GPR) can be trivial or challenging depending on those answers.

 

[supersuk]

The pipe material will either be reinforced concrete or a polymer concrete jacking pipe with a CCFRPM (centrifugally cast fiberglass reinforced polymer mortar) pipe installed inside the jacking pipe.

The ground conditions will be mostly clay and basalt rock with ground water encountered throughout.

 

[dicksewerrat]

I don't know if tracer wire can be detected at 50 feet. There is a trade show in Louisville, KY next week. It is for Sewer cleaners, etc. there will be all kinds of vendors, locators GPR and such. If you are anywhere near there. Check the website, Search Pumper and cleaner.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[bimr]

Here is a discussion:

http://www.ttn.bham.ac.uk/Final Reports/Pipe Location and Assessment.pdf

 

[msucog]

some geophysical methods might give "indication" of where the pipe is but there's a lot of factors at play such as consistency of surrounding soils, size of pipe, accuracy needed on the locate, etc.

 

[LittleWheels]

A tricky situation, you need to talk to somebody better at NDT than me.

 

[supersuk]

Thanks, guys! These are all great comments and thanks for the leads. I'll be reading up more on these.

Unfortunately I won't be able to make it to that trade show in KY.

 

[dicksewerrat]

Well I will, so I'll talk to some people and get back to you.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[dicksewerrat]

Ok I went to a trade show and talked to all the locator vendors. 10 -15 feet deep if you have access to one end of the locating wire. 50 feet no way sorry. You have to have good asbuilts with good control points. Manholes on the sewer make for good control points.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[supersuk]

Thanks for your time Richard. After reading up on the previous options we had I figured it'd be impossible. We've come up with an option to only detect the tunnel under bridge crossings. We will install a tracer line under the road so the tunnel will be easily detectable.

 

[indianjoe]

I see from all the posted answers that no one has ever talked to a city water crew. I thank you may be amazed at what most of the oldtimers will tell you. Sure the crews will have electronic detectors, but I'll bet if you look in their truck you will find two lengths of wire about 2 to 3 feet long with a 90 degree angle about four inches long bent at one end. When all else fails, the crews will get out the old wires an witch the line. I know it sounds nuts, but Ive been an engineer for a very long time, and I have seen lines as deep as 80 feet found. No joke, talk to a city water crew, they will veryify what I have just said.
Oh yes, it doesn't make any difference what material the line is made of or if it is flowing or not or if there is anything in it at all!! Ive seen it done not only for waterlines, but sanitary sewers, oil pipelines, and storm sewers.

Joe Kinnison P.E.

 

[dicksewerrat]

I know 'witch wands' work. but didn't want to put that out there. All those years of study and investigation and what works is 'Magic'? I won money from a surveyor with my set of welding rods

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[supersuk]

I'm sure this won't work in my case is we will be over bodies of water that is flowing to the ocean and ground water which is encountered throughout the site.

I have seen those magic wands work before and am still amazed by it.

 

[bimr]

It would probably be best to leave the dowser rod back home in the closet:

http://www.csicop.org/si/9901/dowsing.html

 

[rconner]

I was kind of waiting to see where this thread was headed (but when the witching rods came out I figured I might oughta resppond). I think many engineers/technologists over the last several years have been looking at locating/mapping issues, and some even using tools e.g. that traverse the inside of the pipeline and work on gyro and I suspect voluminous data processing principles etc.) I incidentally received an e-mail advertisement today that contained the following,

"GEOSPATIAL MAPPING SYSTEMS TO PRESENT SMART PROBETM PIPELINE AND CONDUIT MAPPING TECHNOLOGY AT THE 2008 IEEE PES TRANSMISSION AND DISTRIBUTION CONFERENCE AT CHICAGO'S McCORMICK PLACE NORTH
SARVER, Penn. - (April 15, 2008) - Geospatial Mapping Systems, Inc. (

http://www.geospatialcorporation.com)

announced that it will be exhibiting its Smart Probe TM Pipeline Mapping technology at the IEEE PES meeting billed as "the center of the world for power delivery" from April 21st through April 24th at McCormick Place North in Chicago, Illinois. Please visit us in BOOTH NO. 2097, SECTION 4 to see the variety of probe styles capable of mapping pipelines and conduits ranging in size from 1.5 inches to over 60 inches in diameter.
Geospatial's Smart ProbeTM Pipeline Mapping technology provides accurate and economical pipeline mapping information to electric and telecommunication conduit operators as well as detailed bending radius and joint integrity data -- critical for the safe installation of sophisticated high voltage electrical distribution conduits."

They are probably not the only players in this field, but I suspect the cost of all the electronic options is likely a little more than a couple bent brazing rods. [Incidentally, I happen to have a couple such rods over in the cabinet in the corner of my office, but I'm not sure based on expereince over the years that I'm good enough to take Mr. Randi's $millions.]