Progress in Earthquake Debris Disposal and Soil Remediation - December 2011 to the 2020s

Progress in Earthquake Debris Disposal and Soil Remediation - December 2011 to the 2020s

The 2011 Great East Japan Earthquake generated approximately 28 million tons of debris in Fukushima Prefecture. About 50% of this was wood waste, including a large amount of fibrous material that is difficult to process. The cost of debris disposal was estimated at approximately 37,800 yen per ton, with the total market size reaching approximately 1.5 trillion yen. While the need for wide-area processing was being called for, Fukushima Prefecture conducted an experiment using the grass plant "sorghum" to absorb radioactive cesium, which was found to be up to 200 times more efficient than sunflowers in absorbing the cesium. This plant is also attracting attention as a raw material for bioethanol, and full-scale demonstration cultivation in Fukushima Prefecture has been underway since spring 2012.

In the 2020s, significant progress was made in the disposal of earthquake debris, with the entire process of interim storage facilities beginning operation in March 2020, and the dismantling of facilities that had ceased operation beginning in FY2022. As of 2022, the interim storage facility will hold approximately 14 million cubic meters of removed soil and waste. As of 2024, the number of temporary storage sites will be reduced to about 150, and the total amount of stored waste is also showing a steady downward trend.

In the agricultural rehabilitation of soil contaminated by radioactive materials, phytoremediation using plants was found to be of limited effectiveness, and potassium application was mainly promoted. As a result, the concentration of radioactive cesium in crops has been reduced by more than 90% compared to 2011 levels, and agricultural land regeneration is accelerating.

General contractors Kajima Corporation, Taisei Corporation, Shimizu Corporation, and others participated in the debris removal and decontamination work. In particular, Kajima Corporation played a major role in the wide-area processing in Fukushima Prefecture. In addition, environmental technology companies are responsible for management and sorting at the interim storage facility to support efficient operations.

The number of temporary storage sites for removed soil in Fukushima Prefecture has been decreasing and reduction of the total amount as of 2024 is underway, but securing a final disposal site remains a challenge. The storage deadline for interim storage facilities is set at 2045, and a nationwide final disposal plan is required by then.

Despite the remarkable results achieved so far in the treatment of earthquake debris and soil remediation, sustainable technological development and consensus building among local residents continue to be important issues.