Using MultiBeam Sonar for Culvert/Pipe Inspection

Moderator: Jeff Snyder

Using MultiBeam Sonar for Culvert/Pipe Inspection

Postby rovsteve » Fri Apr 30, 2010 11:13 am

For inspecting the interior of two culverts for a client in South Florida, this week, I attached the BlueView P900-130 multibeam sonar to my Pro 4. The client had requested sonar and I wanted to see how the multibeam performed inside a small space. In the past I have used the TriTech SeaSprite scanning sonar inside culverts with pretty good results.

The resulting sonar images were fantastic. Not only did the unit perform in a superior fashion, the realtime images made navigation and flying inside much easier than relying on the image from the camera. The water was dark, murky and full of floating debris. I inspected two culverts, Number one was a concrete 10 foot by 10 foot box culvert about 300 feet long. Number two was a concrete pipe 10 feet in diameter and 1470 feet long.

The inspection requirements included a survey of the canal basin 60 feet before the entry and 60 after exit to identify any debris that could pose a problem if swept into the culvert, also any scour that could compromise the culvert crib wall was important. The sonar made quick work of this and provided a perfect image of the canal bottom.

The great part was being able to navigate in the canal and then approach the culvert entrance without any uncertainty, the sonar imagery gave me all the information I needed, to know exactly where I was and where I was headed.

Once inside the culverts, the sonar helped me navigate without bouncing around from wall to wall and let me see forward for obstructions. I set the range low to reduce multipath reverberations from the walls. In the round pipe culvert I was able to see a major obstruction before running into it and using the image determined it was where another culvert intersected and had lodged long pieces of lumber into the main culvert creating a dam. This obstruction has resulted in regular flooding events in the past and was a major concern for the client.

Also in the pipe culvert, I was able to establish if it was clear of sediment by observing the sonar returns that imaged the pipe joins every 10 feet. This made it faster to fly the entire length without having to constantly check the bottom for sediment with the camera, normally I could see several pipe lengths ahead.

All and all, the multibeam is a superior instrument for interior pipe and culvert inspections. The BlueView 900-130 I used was a bit of overkill, as either the 900-45 or 900-90 would have done just as well. The only time the 130's wide view was useful was the close approach to the culvert and crib wall.

The following photos are examples of the sonar files from the job.
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Re: Using MultiBeam Sonar for Culvert/Pipe Inspection

Postby rovtom » Fri Apr 30, 2010 5:15 pm

got to love multibeam :D
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Re: Using MultiBeam Sonar for Culvert/Pipe Inspection

Postby Chief » Sun May 02, 2010 6:56 pm

I told you it would work Steve! :D

I had a 600' long by 14' wide tunnel not too long ago. I was amazed when the sonar was able to see car tires on the overhead of the tunnel. I agree with Tom, multi-beam is awesome!

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Re: Using MultiBeam Sonar for Culvert/Pipe Inspection

Postby Jeff Snyder » Mon May 03, 2010 4:42 pm

Very nice, Steve. You know, there are some folks who want to see the Micron/SeaSprite or a profiling sonar used in these culverts/tunnels to measure sediment buildup. But in this case, as you've demonstrated, the multibeam forward-looking sonar is a superior tool because it not only aids with your situational awareness, but it also allowed you to determine (by virtue of seeing the pipe joints) whether there was any sediment build-up of note. Perhaps the best way to handle an inspection like this is to utilize the multibeam sonar on initial runs; once it is determined that sediment exists and that a full penetration can be performed safely, additional penetrations using the Micron/SeaSprite to profile the circumference of the tunnel at known stations can be performed and used to make sediment quantity estimates.
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Re: Using MultiBeam Sonar for Culvert/Pipe Inspection

Postby rovsteve » Sat Jul 03, 2010 5:16 pm

BlueView Technologies, the manufacturer of the ProViewer 900-130 multibeam sonar I have been using to conduct interior culvert inspections in Florida have posted a very nice video clip of the process on their website. It explains the process and the why the sonar is important. Suggest you log on and view it if you are considering doing this type of work.

Just click on this to view: http://www.blueview.com/2D-Culvert-Inspection.html

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