#Fukushima I Nuke Plant Groundwater Contamination: TEPCO's Ad-Hoc Underground Impermeable Wall in Embankment Made It Worse

This is just too ... (I can't even come up with the right word to describe).

Amateurish, maybe. Pathetic, maybe. And sad.

Because radioactive materials started to get detected in June this year in observation holes along the embankment in orders they didn't expect, TEPCO hastily decided in early July to inject waterglass in the soil of the embankment to create an impermeable wall in the ground. Since it is hot during the day at the plant, they made the workers work at night in full protection gear, from 7PM to 7AM, in the area with high radiation.

According to the articles below, we now know what many of us may have been suspecting all along. The idiom "Haste makes waste" exists for TEPCO.

It turned out that injection of chemicals to create the impermeable wall was too successful. It not only stopped the flow of groundwater, but raised the groundwater level significantly. So now, the groundwater is probably going up and over the hastily built underground impermeable wall, and through the porous, top part of the embankment into the open culvert.

The embankment is artificial, built on top of a natural sandy beach which had existed before the plant was built. There is no way to inject chemicals to solidify the top 1.8 meters. Even if it is possible, the water will simply go around the sides.

(The opening sentence of Nikkei's article below is wrong, though. There is no highly contaminated water leaking from the plant, yet. The highly contaminated water is mostly in the underground trenches, where it has been since 2011. Some may be leaking into the groundwater flowing from the west and that groundwater may be leaking into the open culvert.)

From Nikkei Shinbun (8/3/2013):

福島第１の汚染水、地下の遮水壁越え海に流出か

Contaminated water from Fukushima I Nuke Plant may be leaking into the ocean over the underground impermeable wall

東京電力福島第１原子力発電所から高濃度に汚染された水が流出している問題で、地下の「遮水壁」を乗り越えて海に漏れ出ている可能性が高いことが２日、明らかになった。原子力規制委員会の作業部会で、更田豊志委員らが指摘し、東電も認めた。魚など海洋生物などへの影響が懸念されるため、規制委は東電に緊急対策を指示した。

Regarding the problem of highly contaminated water leaking from Fukushima I Nuclear Power Plant, it was revealed on August 2 that it was highly likely that the contaminated water is going over the underground "impermeable wall" and leaking into the ocean. Nuclear Regulatory Authority's working group met on August 2, and commissioners including Toyoshi Fuketa pointed out the possibility and TEPCO admitted to the possibility. As there are worries over the effect on marine creatures including fish, Nuclear Regulatory Authority ordered TEPCO to come up with emergency countermeasures.

　東電は地下の汚染水が海に流出するのを防ぐため、７月上旬から護岸沿いに水ガラスと呼ぶ特殊な薬液を注入して土を固め、遮水壁をつくる工事を進めていた。遮水壁は地下1.8メートルよりも深い部分に設置されている。

In order to prevent the underground contaminated water from leaking into the ocean, TEPCO has been injecting special liquid called waterglass [sodium silicate solution] along the embankment to solidify the soil and build an impermeable wall since early July. The wall is set deeper than 1.8 meters from the surface.

　作業部会は地下水の水位が最近になって上昇し、遮水壁の上端部を越えた可能性が高いとの結論に達した。壁で地下水をせき止めたのが原因とみられる。地下水は壁を乗り越えるほか、横からも漏れる恐れがある。

The working group came to the conclusion that because the underground impermeable wall stopped the flow of groundwater, the level of groundwater rose recently, and went over the top of the wall. Not only the groundwater could go over the impermeable wall but go around the wall and leak from the sides of the wall.

　東電は遮水壁の近くに井戸を掘り、地下水をくみ上げて水位を下げる工事に着手。今月末までの完成を目指す。地下水は山側から１日に100トンほど流れ込んでおり、これを超す量をくみ上げる必要がある。水の保管方法などは今後検討する。

TEPCO will start digging wells near the impermeable wall to draw groundwater and lower the water level. The company hopes to finish by the end of this month. Groundwater is flowing in from the mountain side (west) at the rate of 100 tonnes per day, and TEPCO needs to draw more than that amount. Storage of the water thus drawn will be discussed later.

(Diagram from Nikkei Shinbun, English labels are by me.)

Now, what is the point of drawing the contaminated groundwater along the embankment? In haste? Particularly when the levels of cesium, all-beta, and tritium in the open culvert have not risen in a significant manner? Do they even stop and think?

They have to somehow stop the groundwater upstream, before it reaches the space between the turbine buildings and the embankment and gets contaminated.

According to an article by Mainichi Shinbun that only appeared in Fukushima local edition (7/24/2013), the embankment was a landfill:

この一帯は原発建設時の１９６０年代に埋め立てられたもので、東電は「なぎさに泥岩、砂岩を積み上げてできた土地」と説明する。

This area was reclaimed in the 1960s when the plant was being constructed. TEPCO explains that the land was made by piling up mudstones and sandstones on the beach.

And just like anything else - from removing fuel rods from the spent fuel pools to removing the corium from the broken reactors - TEPCO has been made to promise the wells will be dug "ahead of schedule", starting this weekend, according to Yomiuri Shinbun (8/6/2013).

The Yomiuri article makes no mention of what will happen to the water drawn from the wells.

What's the point of drawing the water "ahead of schedule" when you don't even know what to do with it?

I am more convinced that construction of the impermeable wall in the ocean by driving sheet piles in the open culvert with vibratory hammer has caused the leak by disturbing the underground trenches and joints that were already damaged by the March 11, 2011 earthquake and tsunami. The trenches and shafts were filled with highly contaminated water from April/May 2011 leak from the turbine buildings for Reactors 2 and 3.

TEPCO did not want to deal with the highly contaminated water, and instead decided to inject waterglass, thinking that would stop any water from flowing into the ocean.

My guess is that by hastily injecting waterglass TEPCO wanted at least few weeks of non detection or low detection of radioactive materials from the observation holes, so that they could somehow proceed on releasing the uncontaminated groundwater drawn from upstream into the ocean.

For now, TEPCO cannot release any water, and groundwater keeps flowing from west to east without any hindrance.

The photo below is from July 16, as workers injected waterglass in an effort to stop the groundwater (from TEPCO's Photos and Videos Library 7/17/2013):

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