Minato and Chiyoda Wards, Tokyo / Sano City, Tochigi Prefecture - Oil Contaminated Soil Remediation (around 2007)

Minato and Chiyoda Wards, Tokyo / Sano City, Tochigi Prefecture - Oil Contaminated Soil Remediation (around 2007)

In the early 2000s, oil-contaminated soil became apparent at former factory sites and urban redevelopment projects in Japan, and the Soil Contamination Countermeasures Law enacted in 2003 triggered widespread investigation, notification, and action. Although petroleum hydrocarbons are not necessarily included in the substances designated by the law, they must be treated in accordance with local government guidelines and voluntary standards, and "prompt, reliable, and reusable treatment" became essential for urban redevelopment projects. Against this backdrop, "Solec Tochigi," established by Kajima Road (Hibiya), Nichie (Chiyoda-ku, Tokyo), and Otosaka Crushed Stone Mining (Sano-shi, Tochigi), attracted attention as a practical model for purifying and recycling contaminated soil generated in urban areas in local communities.

The core of the facility is a low-temperature heating system (LTTD): oil in the soil is volatilized and evaporated in a rotary furnace and dryer heated to 150-350°C, and the gas generated is oxidized at high temperature in an afterburner and removed in a bag filter and washing tower. After treatment, the residual oil content of the soil is lowered below the standard, and the soil is reused for landfill at quarries or as soil preparation material, thereby curbing final disposal. Soil transported from urban areas is removed by covered dump trucks, and the receiving facility reduces environmental impact through inspection, odor control, and mist spraying. Transparency was ensured through manifest management and rapid analysis.

The advantage of LTTD was that it could process large volumes in a short period of time and was more suitable for materialization than incineration. Around 2007, with high crude oil prices and pressure to reduce emissions under the Kyoto Protocol, energy efficiency and LCA were also considered important. This initiative, which linked urban redevelopment with local resource recycling, was highly significant as a pioneering example of how to simultaneously achieve environmental conservation, material reuse, and regional development.