Summary of the review result of the project for the managed recycling at the Kasumigaseki flower gardens

Date: October 21, 2025

1. Background

• On September 5, 2025, the applicant requested a review for the project of the managed recycling for the Kasumigaseki flower beds.
• This project involves the use of removed soil for managed recycling (approximately 66 m³ in total) in nine locations, including flower beds at central government offices in Kasumigaseki.

2. Summary of the review result

• The contents of the plan for this project is recognized to be in compliance with the ministerial ordinance to provide for criteria and appropriate in accordance with the precautions set out in the guidelines.
• The construction work at the site was also deemed to have been carried out appropriately in accordance with the above plan. Changes from the original plan, such as the amount of the removed soil for managed recycling to be used, are also in accordance with the ministerial ordinance to provide for criteria, and recognized to have been carried out appropriately in accordance with the precautions in the guidelines.

Main review matters	Review result
Radioactivity concentrations in the removed soil used	Removed soil with a radioactivity concentration of 8,000 Bq/kg or less is used to ensure that the additional dose for the workers and the general public is kept at 1 mSv/year or less.
Measures to prevent the scattering and runoff of the removed soil for managed recycling	In addition to placing soil at least 20 cm thick to cover the removed soil, the soil is kept sealed in sandbags when temporarily stored and other measures are taken to prevent scattering and runoff during construction, such as using protective sheets as needed.
Radiation dose monitoring	The monitoring methods and frequency, etc., before construction, during construction, after construction and during maintenance comply with the ministerial ordinance to provide for criteria and guidelines. On-site measurements are also conducted appropriately, and the measurement results for all the points in the construction site are posted on the website.
Responses in the event of abnormal occurrence, emergency repairs, etc.	In the event that damage is caused to the construction site where the removed soil is used due to a natural disaster or other reasons, response measures（emergency repairs and permanent repairs）are in accordance with the guidelines.
Changes from the initial review	In some construction sites, such as Building No. 8, on site excavation results and others showed that the amount of the removed soil used was less than originally planned, but it was confirmed that the construction was done appropriately in accordance with the ministerial ordinance to provide for criteria and guidelines. At the Ministry of Foreign Affairs, as the construction plan had changed since the initial review, the amended review of the construction plan was conducted , and it was confirmed that it complied with the standards and that the construction was properly carried out on site

Checking the construction site（thickness of the filled soil）
（Ministry of Economy, Trade and Industry）

Monitoring during the construction
（Building No. 5）