” Bags of radiation-contaminated soil could be sinking into the ground at temporary storage sites in Fukushima Prefecture, allowing water to accumulate within instead of flowing to outside tanks for testing, the Board of Audit said.
No confirmation has been made that the ground at the sites is actually sinking or if contaminated water has pooled inside. But Board of Audit officials are asking the Environment Ministry to consider additional safety measures if signs indicate that this is actually occurring.
The board’s study focused on 34 of the 106 temporary storage sites that the Environment Ministry set up for soil removed through decontamination work after the disaster in March 2011 unfolded at the Fukushima No. 1 nuclear power plant.
Construction of the storage sites started in 2012, and the transfer of contaminated soil to these facilities was completed in 2015.
The temporary storage sites were designed to have a slight mound on the ground in the center to allow water from the bags to flow down into surrounding collection tanks for periodic measurements of radiation levels.
Internal Environment Ministry guidelines called for this setup at storage sites containing bags that are not waterproof.
The Board of Audit studied 34 temporary storage sites where the bags are not waterproof. These bags were piled five deep or higher at those sites.
The study showed that at 31 of the sites, the weight of the bags may have not only flattened the mound in the center, but it also could have created an indent in the ground where the leaking water could accumulate.
If the water does not flow to the tanks, it will be difficult to determine the radiation levels.
The study also noted that the foundations at the sites were soft to begin with and may be unable to support the bags of soil. The sinking phenomenon could worsen as time passes.
The Environment Ministry played down the risk of the water contaminating areas around the storage facilities.
“Even if the ground has sunk, the structure is designed so water does not leak outside the site,” a ministry official said. “Eventually, the water should collect in the tanks. We will make every effort to oversee the sites as well as use waterproof bags as much as possible.”
A total of 4.16 billion yen ($40 million) was spent to construct the 31 temporary storage sites.
The Environment Ministry designed the temporary storage sites under the precondition they would be used for only three years and then removed. For that reason, measures were not taken to strengthen the foundations to prevent the ground from sinking, even if soft farmland was chosen for a site.
The plan is to eventually return the land where the temporary storage sites have been built to its original state and return it to the landowners.
However, the Board of Audit’s study adds another concern for residents, many of whom had opposed construction of the temporary storage sites in their neighborhoods.
Toshio Sato, 68, has evacuated to Fukushima city from his home in Iitate village, where four of the possible problem storage sites are located.
“There are some people who want to resume growing rice once they return home,” Sato said. “If water is accumulating, there is the possibility it could unexpectedly overflow into surrounding areas. The concerns just seem to emerge one after another.”
The government plans to lift the evacuation order for a large part of Iitate in March 2017. ”
by Kosuke Tauchi, Shoko Rikimaru, Kenji Izawa and Akifumi Nagahashi