The History of Tokyo Bay New Sea Surface Final Disposal Site (1995-2020s)

The History of Tokyo Bay New Sea Surface Final Disposal Site (1995-2020s)

In 1995, Tokyo and Chiba Prefectures agreed to establish a new final disposal site for waste in Tokyo Bay, known as the "New Sea Surface Disposal Site." This plan involved constructing a disposal site covering approximately 480 hectares off the coast of Kisarazu City, Chiba Prefecture, with an annual intake of 140 million tons of waste. The waste included construction debris, industrial waste, and incineration ash from household garbage, all requiring appropriate handling for hazardous materials such as PCBs and heavy metals. Major construction companies such as Kajima Corporation, Shimizu Corporation, and Taisei Corporation participated in the project, with environmental protection technology provided by Sumitomo Metal Mining and Hitachi, Ltd. Concerns were raised by local fisheries cooperatives and residents in Chiba Prefecture, leading to discussions on fishery compensation and ecosystem impact assessments.

Entering the 2020s, the New Sea Surface Disposal Site has continued to play a vital role in waste management for the Tokyo metropolitan area under the management of the Tokyo Metropolitan Government's Port Bureau. The landfill area is equivalent to about 100 Tokyo Domes, with 319 hectares used for waste disposal. Waste types include incineration ash, non-burnable waste residue, and oversized waste residue, with an annual landfill disposal volume estimated at approximately 500,000 tons in the 2020s. Thanks to efforts to reduce and recycle waste, the volume of landfill has been decreasing compared to initial projections in 1995.

Given the difficulty of constructing new disposal sites within Tokyo Bay, measures to extend the disposal site's lifespan have become a priority. Specific initiatives include promoting the reduction, reuse, and recycling (3Rs) of waste, recycling incineration ash into cement and roadbed materials, and improving landfill efficiency.

Environmental preservation measures have been strictly implemented, including leachate management, landfill gas control, and environmental monitoring. Leachate is temporarily stored in a collection pool, then regulated for water quality and quantity in an adjustment pond before being treated at a drainage treatment facility. Landfill gas, mainly methane, is collected through gas extraction wells and subjected to combustion or energy utilization assessments. Regular monitoring of the quality of nearby marine and air environments is also conducted to oversee environmental impacts.

The New Sea Surface Disposal Site, adjacent to the central breakwater outer landfill area in Koto Ward, Tokyo, is expected to continue serving as a key waste management center. Tokyo has formulated the "9th Revised Tokyo Port Plan" for the 2040s to further develop a sustainable waste management system.