Earlier this month, the Forum On Energy wrote about a groundwater bypass system being put in place at Fukushima Daiichi to stop radiation-contaminated water from entering the Pacific Ocean. One of the key pieces of this system has understandably drawn some curious comments: An underground “ice wall” to redirect the water.
However, despite the general public’s lack of familiarity with the process, ice walls aren’t something out of science fiction. They have actually been in use in the mining industry since the 1880s. They were even part of two recent, large-scale U.S. infrastructure projects, at Boston, Mass.’s “Big Dig” interstate project and the New York East Side Access project.
Essentially, extremely salty water at -30 Celsius is pumped deep underground, freezing the water in cracks and pores, thus binding rock and soil together in a thick mass that provides strength and reduces permeability. At Fukushima, cleanup engineers will install 1,550 pipes at 33 meters deep to create an ice wall in order to block groundwater from passing beneath the plant—where it risks contamination—and flowing into the ocean.
Read more about the ice wall project at TheConversation.com.