Walls to halt tainted groundwater from flowing into sea completed at Fukushim

TEPCO officials said the underground walls will reduce the daily flow of contaminated groundwater into the sea from the previous estimated 400 tons to 10 tons.
However, they said it will take a month or two to confirm the effectiveness of the barriers.

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201510260048

Tepco completes sea wall at Fukushima No. 1 nuclear power plant

Until Monday, about 400 tons of groundwater was draining along the sides of the buildings and into the sea each day, after being contaminated with fallout from the 2011 meltdown crisis, according to Tepco.
The utility says an estimated 150 tons of underground water is still flowing into the basements of the damaged reactor buildings each day.

 The Nuclear Regulation Authority has yet to give permission for the operation, saying creation of frozen soil could drastically change the underground water level around the plant. If the water level outside falls lower than that inside, the contaminated water could leak out. Meanwhile, Tepco has not explained exactly how it will control the water levels, an NRA official said.
http://www.japantimes.co.jp/news/2015/10/26/national/tepco-completes-sea-wall-keep-toxic-fukushima-no-1-water-reaching-sea/#.VjDszyvlxbK