After reading many Internet posts on the method they are using to divert the Underground water, Deuem wants to toss his ideas in the ring.
I see that they are putting a coffer dam in at the sea wall = I say useless.
I see that they put in or are thinking of a square coffer ring around the plant at a shallow depth. = I say useless.
Water will seek its own level. In this case the sea. Can't really stop it, But you can divert it.
A coffer dam should be pounded in, in the shape of a V in front of the plant. Or on an angle to the lowest side. This is on the mountain side. This steel sheet should be driven into bedrock. Core samples to be taken every few meters to be sure where the water is. After the dam is up then drill holes down to bedrock first on the inside and inject a concrete slurry to harden the ground and make it solid. Solidification stops water. If it is working then you should see water coming to the surface as it is being done.
This is not a new idea, people have been doing this to re-claim lost wet lands where needed. The slurry penetrates the soil and then hardens. The water must go somewhere else.
When the water table rises at Fuku it will just go over or around the sea wall dam they have now. That sea wall dam can not stop it, just push it over, under or sideways.
When I saw the ice idea I cound not see anyway that could work. Very temporary if it worked at all. Very expensive and requires a lot of electricity to work.
You can also control the angle and depth of the slurry insertion, so they can place it anywhere they need. I have seen sites filled and the water rises to the surface then runs off. After that any ground water is diverted.
Cement is cheep, our lives are not.
Also wells can be dug later on the mountain side and pull the water away long before it hit the slurry wall. Divert the water at the source. Run wells every 10 meters and pump it out. If all the wells are running at full speed, then add more, larger ones in front of them. Pump the source dry and be sure to have enough to take care of rain water.
When the front of the coffer dam get dry, slurry it also.
Deuem