Newbie with MAJOR problem...

[waste]

Dog, welcome to the forum You say you have air bubbles in the pump, is there a chance that the pipe itself was breached allowing the concrete in, in the first place? If so, have care removing the obstruction as you might cause a fatal leak in the pipe (using power equipment or excessive force is also not a good idea as the pvc pipe will probably give before the concrete). If the crete was just a glob that ended up in the pipe a good poke should have freed it, I fear the pipe was compromised before the crete was poured/ shot (pvc & crete don't bond very well).
I would suggest keep doing what you have been (I know, pain in the @$%& and all those trips to the dive shop to refill). If you want to get a hammer and 1/2" cold chisel involved, have someone topside hold you down with your wallbrush, but be careful about the pipe. Once you get it down to ~ 1/4" mix up some 2 part epoxy (any plumbing store will have some) and generously coat the entire area, making sure that you have a good layer over the remaining concrete and adjacent pipe. Wish I could offer a better solution, but I believe this will take care of the problem. GOOD LUCK! - Waste

[duraleigh]

Dog,

Listen to "Waste"!

Bangin' on that PVC with power equipment or a sledge is an invitation to a much larger problem.

As an aside, it doesn't seem to me this is the source of a suction side air leak. It's not clear to me how air could be entering the system that far underground

[CarlD]

Dog,

Listen to "Waste"!

Bangin' on that PVC with power equipment or a sledge is an invitation to a much larger problem.

Hey! I was gonna suggest dynamite next! Are you saying that might not be a good idea?

[MyBlueDog]

Thanks.

Question for the engineers/scientists: Wouldn't a main drain suction blockage at 6' underwater, and a pump surface side 2' above cause the pump to pull oxygen from the water.

My thinking is since water contains O2, that any blockage in the main drain would restrict flow, causing the pump to work at the same rate, yet pull O2 from the water at a faster rate than it actually sucks the water.

Make sense?

[JJ in Tx]

How about a air chisel like on this page,used very carefully of course.

[MyBlueDog]

How about a air chisel like on this page,used very carefully of course.

Can you run an air chisel underwater?

[JJ in Tx]

Never tried but was figuring that the "power" was all coming in thru the air hose and everything happening on/at chisel was exhaust from the operation. would make sure i oiled tool prior to and after use as well as run it a bit once it was out of the water to make sure it was "dry" before storing it.
JJ

[KurtV]

Thanks.

Question for the engineers/scientists: Wouldn't a main drain suction blockage at 6' underwater, and a pump surface side 2' above cause the pump to pull oxygen from the water.

My thinking is since water contains O2, that any blockage in the main drain would restrict flow, causing the pump to work at the same rate, yet pull O2 from the water at a faster rate than it actually sucks the water.

Make sense?

I don't think you can "pull" dissolved oxygen from water with suction. If you could oxygen from water that easily, you probably would have been using a device that does that instead of a tank for your dives. (There are some devices for diving that allow you to extract breathable oxygen from water but I don't think the methodology is simple suction.)

Trying to think a little out of the box, is there any way you could drill a hole in the concrete chunk, insert a lead anchor, thread a lag bolt into the anchor, and pull the chunk out with a big pair of pliers?

[mshumack]

Can you run an air chisel underwater?

yes, an air chisel will work underwater but you won't be able to see what your doing with all the bubbles from the exhaust (the ones I've seen all exhaust through the handle or body). If there was a way to vent the exhaust through a hose to some distant location ...

[South_Texas_Sun]

How about using an air drill with a masonry bit, putting a bit of electrical (waterproof) tape at a fixed depth on the bit (to avoid drilling through the bottom of the chunk and through the PVC) and drilling a hole for a concrete fastener?

Best case, you drill a pilot hole for a concrete screw (don't know the right name for them, but they have 'em at Lowes, etc) Then you use a wratchet/socket and install the screw. Grab screw with vise-grips and gently tug it out.

Worst case: Drilling and tapping breaks chunk in half and comes out in pieces.

CYA disclaimer: Be sure to unplug the air compressor before starting to drill, just in case the air hose has metal sheathing all the way down to the coupling!