I'm having one of those moments that leaves me wondering wether or not there's something I'm missing. I was reading about the latest woes TEPCO have been having at Fukushima and it seems to me they're missing thed obvious solution. The little that I have been able to gather is that the problem they are having is one of groundwater containment. They pumped some chemical into the ground that hardens to make the soil impermeable, btut, it's only effective at depths >1.8m and there are concerns about it overtopping as the groundwater continues its inexorable trek from the hills behind the plant to the ocean in front of it. It seems to me that there's an obvious solution. Dig two paralell trenches around the plant (or around reactors one and two). Fill the outermost trench as a slurry wall. For bonus points you can line it with geotextile. Fill the innermost trench with pea gravel and place a pumping well every twenty meters or so. Trench depth is dependent on soil hydraulic conductivity. The basic idea is the slurry wall diverts flow around the affected area, while the pumping setts up a negative hydraulic gradient containing any groundwater contamination in much the same way a negative pressure environment contains airborne contaminants Pump, condense, store, dispose. It seems such an obvious solution to me that it leaves wondering what I have missed.