Drilling/Chipping: Underwater

So I have an interesting question. I used to work out at a camp and they have recently contacted me for some assistance. We have some underwater concrete pots that were used to anchor docks and so on. We are trying to get these out of there as they are too big to carry and they are now in the diving areas. The issue is they are just too darned big to move.

So the idea is to chip/crack them into manageable sizes and go from there. But I can't figure out how to crack these suckers underwater. We have hammers and screwdrivers. We have chisels and a couple crowbars. But some of these stuff is down at like 8 feet. So. Does anyone have any ideas? Even if we are just busting chunks off that is fine. We just need to get them small enough that the thing won't be considered a hazard. Some of the stuff is sunk down in the mud too, so it is basically impossible to lift unless we crack them.


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If they big and aren't too far from shore you build a caisson, pump the water out then dig the footings out.

If they are smaller (like a yard or less of concrete) you should be able to get a chain on them, hook up a block and tackle and drag them out.

Lutherf said:

If they big and aren't too far from shore you build a caisson, pump the water out then dig the footings out.

If they are smaller (like a yard or less of concrete) you should be able to get a chain on them, hook up a block and tackle and drag them out.

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Sadly they are just so far from the hill that any clever engineering for water is probably out. The block and tackle is a good idea though. We can for sure do that with some of the stuff closer to the docks.


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Know anybody with a truck or a jeep with a winch?

I think if you ground the end of a 1 inch piece of steel rebar to a point, from a boat it would let you transfer the energy down to the concrete.
An air hammer, or even a palm nailer might work.
It would help to have someone down there when you started, to keep the point in the concrete.

Gonzo Rodeo said:

Know anybody with a truck or a jeep with a winch?

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Too far

Was one of the first things we wanted to try. It is a long ass way. Like 100 yards or more just to be above it. Plus it is a super steep incline where you can park any kind of truck (because it is a spring fed lake with steep sides).


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Come-a-long (you'd need a fairly strong one, the 2 ton ones are only 15$ but you'd probably need stronger than that.) + chain? Anchor on a tree, assumes you can get a chain secured around the concrete. Anyone with you who happens to have SCUBA gear would also be a god send no matter what strategy you go with. But I can see you working it out a few feet at a time with a strong enough come-a-long and enough chain. Like someone else mentioned, breaking it up by striking it is going to be tough as the water will kill your momentum before impact unless you have a chisel that can rest on the concrete and still be sticking out of the water.

Do the jeep thing with a pully at 90 degrees if doable.

shagg said:

Come-a-long (you'd need a fairly strong one, the 2 ton ones are only 15$ but you'd probably need stronger than that.) + chain? Anchor on a tree, assumes you can get a chain secured around the concrete. Anyone with you who happens to have SCUBA gear would also be a god send no matter what strategy you go with. But I can see you working it out a few feet at a time with a strong enough come-a-long and enough chain. Like someone else mentioned, breaking it up by striking it is going to be tough as the water will kill your momentum before impact unless you have a chisel that can rest on the concrete and still be sticking out of the water.

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Your know. We actually do have someone who is scuba certified. And we have some long metal stuff that may work. And we may have access to a come along. I think we have some ideas to work with. Thanks.


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Never let a chance to use explosives go to waste.

Well. The long pieces of metal with a sledge above water worked. We also were able to dig a couple things up and use some long climbing rope to lift and drag it all to shallow water where we could drag it out easier.


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