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Mechanical Sub Sea Tunnel Cleaning

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stanier

stanier

Mechanical
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Is there available a company that markets or designs/constructs a mechanical cleaning device for the internals of sub sea tunnels.

What is required is a machine to clean 2km tunnels 2.8m diameter that are 60m below the surface.

These are intake and outfall tunnels for desalination plants. The client is paranoid about biological growth and does not believe that shock chlorination can be relied upon to remove molluscs etc.

 
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Recovering a stuck pig 60m subsea in a 2km tunnel is a real OH&S nightmare.

In Florida they lost the lives of divers in such circumstances. Entry into subsea tunnels is not an option.

Also launching and reciving facilites would need to be sub sea. Has this been done before?

 
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Real interesting problem. Were the tunnels excavated by drill and blast techniques or by boring ?? Are they concrete lined, steel lined or raw rock?? Any suggestions I might make would depend on these answers.

I wouldnt eliminate conventional divers immediately. I remember many years ago reading about a flooded mine that sent divers down a flooded shaft 300 metres + and then they had to go laterally along a tunnel to close a valve that had been left in the wrong position. Your problem would be trivial compared to what those men had to achieve and it was done sucessfully.

And I have done some work on the intake tunnels of water treatment plants. Your client's concerns might not be over stated. I didnt have barnacles to deal with but there were some impressive algae type growths that appeared to me to be potentially cancerous but I was assured that growths like this were not cancerous but were not uncommon... this in a clean drinking water supply system!!!!!!!!
 
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Tunnels will bored. Mainly concrete lining but some sections lined with PE in an attempt to reduce biological growth near the outlet and inlet sections.

The idea of dewatering the tunnel in order to clean it is not favoured by the client but is capable of being achieved.

 
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OK, the fact you are not dealing with raw rock is in your favour. If this were my problem, I think I'd investigate getting cameras into the tunnels to evaluate the actual conditions.... not much point in devising an expensive cleaning system if theres no real problem, only the perception of one.

Im not a diver but I believe that 60 metres depth is relatively trivial but the 2 km distance will cause safety concerns. All recreational and commercial divers work on a buddy system and at 2.4 metres diameter at least you have the room for two(or more) men to work in close proximity. If for any reason this is not acceptable I believe there are small submersible craft.. essentially mini submarines that might be small enough... these might be manned or completely remote control. Whether they can travel in reverse I dont know.

If this is impractical are there any sections of the tunnel where you could set up a drill on land and drill down into at least one point in the tunnel. Conventional mining diamond drills will give you a three inch hole very easily with a 2,4 metre target only 60-100 metres away.


If this is practical , I am sure some sort of steerable camera is available, altho Ive never had cause to try this.
You could then investigate the use of compressed air to scour the walls.... hopefully by remote control because visibility for divers would be zero.

Does any of this make sense or am I stating the obvious???
 
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Hi Miningman,

Yes that is the sort of brainstorming I have been doing. I was hoping that there was specialist manufacturer out there somewhere who had done it before.

Camera equipment is petty small these days and robots can be created that can be put into the tunnel and allowed to travel with the flow.

Perhaps conventional pigging may be the answer. Just have to design the launch and receivel facilities.

 
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There is a tunnelling contractor in france called CSM BESSAC ( they have a website ). They manufacture their own equipment. Recently they constructed a machine to clean city sewers. I can imagine they could manufacture a tailor- mad machine for your needs
 
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I think that divers would be out of the question due to umbilical length.

ROVs that"fly" would tend to bounce off the walls.

Tracked / wheeled vehicles would be the way to go with a winch for recovery in case of breakdown.

Otherwise winched scrapers would work. You would have to use the water flow or a tracked vehicles to get a pilot line through and then I would suggest Dyneema rope for the pulling.

Stephen Argles
Land & Marine
 
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cvg
We do not only want to inpsect but mechanically clean?

 
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both the companies I linked perform underwater tunnel maintenance repair and cleaning also
 
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A 2.8m diameter pig? That is one big pig. Sealing against the concrete lining might be a problem so I dont think you would be able to use the pressure to drive the pig, which is how pigs are driven through subsea pipelines. You might be able to tow it, or give it its own motive force.

Could you use water jet cleaning?

This is used subsea for cleaning marine growth off platforms and subsea facilities. Most soft marine growth can be cleaned off by hand fairly easily, but you would need something more substantial for encrustations. This would still need some means of delivery over the 2km.
 
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