Japan's nuclear disaster in 2011 focused clean-up efforts in Fukushima prefecture. But neighboring prefectures were also affected, including soil contamination.
The government plans to set guidelines as early as possible for final disposal of the soil underground.
It was removed and stockpiled at thousands of sites in nearby prefectures. Many of the temporary storage sites are in residential areas, including parks.
The Environment Ministry says 329,000 cubic meters of soil is currently stored in seven neighboring prefectures. They are Iwate, Miyagi, Ibaraki, Tochigi, Gunma, Saitama and Chiba.
The ministry has been running safety tests for burying the soil since last autumn in Ibaraki and Tochigi.
It remains to be seen whether citizens living near proposed final disposal sites will accept the plans.
The ministry says it will also study recycling the soil in public works projects to reduce the amount to be buried.