Osaka City, Tokyo Toyosu (Koto-ku, Tokyo) - Plow field restoration (around 2007)

Osaka City, Tokyo Toyosu (Koto-ku, Tokyo) - Plow field restoration (around 2007)

In the 2000s, with the decline of industrial areas in Japan's metropolitan areas, "brownfield revitalization," the conversion of former factory sites into residential and commercial facilities, became an important policy issue. However, heavy metals, oils, and volatile organic compounds were detected at many former sites, creating serious obstacles to urban redevelopment. the Soil Contamination Countermeasures Law, enacted in 2003, required landowners to conduct surveys and take cleanup measures, and clarified "environmental risk elimination" as a precondition for redevelopment.

In Osaka City, the reuse of former petrochemical complexes and steel-related facilities in the bay area became a focal point, and the local government, general contractors, and environmental companies collaborated to introduce soil cleaning, solidification and stabilization, low-temperature thermal desorption, and soil gas suction. The conversion of the site into a logistics base and condominium development was promoted. With the introduction of these technologies, redevelopment gradually took shape.

Meanwhile, in Tokyo, the former Tokyo Gas factory site in Toyosu attracted nationwide attention when surveys from 2001 onward detected benzene and cyanide compounds 1,000 times higher than the standard, raising strong concerns about plans to convert the site to a food market. The cleanup cost was estimated at approximately 67 billion yen, making it a major point of contention for the Tokyo government. Technologies such as excavation removal, groundwater treatment, and the use of impermeable walls to prevent diffusion were introduced, and large-scale cleanup and long-term monitoring were deemed necessary.

These cases showed that brownfield restoration is not simply an environmental engineering issue, but a social governance issue involving urban planning, economic policy, and consensus building among residents. The Toyosu issue, in particular, has sparked social debate over administrative accountability and transparency, and became a case that symbolizes the difficulty of "balancing the environment and the economy" in Japan's urban renewal efforts.