One of the challenges of the ongoing clean-up efforts at Fukushima Daiichi is the geography of the region. Pinned between a hillside and the seaside, the nuclear plant is faced with a constant flow of groundwater, which — if left untreated — can become contaminated with radioactivity before entering the Pacific Ocean. The Tokyo Electric Power Co. (TEPCO) estimates that an average of 400 tons of groundwater flow into the site each day.
TEPCO recently enacted a groundwater bypass system to prevent further groundwater contamination while also reducing the burden of storing the contaminated water, which even then leaves the area vulnerable to leaks in the storage facilities.
TEPCO uses wells to pump groundwater originating from the hillside to a temporary storage site before it can reach the damaged reactors. There, the water is then tested for radiation. When the results come back clean — and, TEPCO notes, its standards for passing will be stricter than the World Health Organization’s drinking water standards — the water will be allowed to pass safely into the ocean.
To further shield the groundwater from the contaminated site, TEPCO is also building a barrier around the plant. On the seaside, there will be an impervious wall to suppress groundwater’s passage to the sea, while on the hillside, an underground frozen soil wall will stop groundwater before it can entire the site.
TEPCO has released a series of videos detailing its plans and goals for the groundwater bypass system.