A series of large-scaled tunnel constructions planned in Tokyo have caused issues of surplus soil. If it becomes more difficult to find soil treatment yards, it can lead to delays of works. It is urgent to take actions against it.

Ministry of Land, Infrastructure, Transport and Tourism has finished its work of a 1.9 km-long west bound tunnel of undersea Tokyo Port Tunnel this month, excavating the total of approx.230 thousand cubic meters.The faster excavating a shield machine is capable of, the more difficult it is to secure the soil yards, Ministry’s official said. Besides 9 m3 for reclamation at Tokyo Bay, and 1 for embankment at Arakawa River, remaining 13 m3 is left with no decisions, searching for solutions such as cement production.

Tokyo Metropolitan Government has also issues of soil treatment. The completion of construction of Shirakogawa underground retention basin (length: 3.2 km) produced 350 thousand m3 of earth left. While anoutside material recycling agency accepted 190 thousand m3, the rest was delivered to cement factories. Though it was able to deal with all soil this time, a Tokyo official said, it could have cost more if the soil had to be transported to remote facilities. If it’s not possible to find treatment yards nearby, it is unavoidable resulting in increase in cost.

To make matters more serious, Tokyo is expecting several plans of large-scaled tunnel construction, which will increase further demands for soil treatment. In addition to an east-bound route of Tokyo Port Tunnel, excavation of a 16km long section of Tokyo Outer Ring Road will start in two tunnels with a diameter of 16 meters each. It is estimated that the amount of surplus soil reaches more than 6.4 million cubic meters.

Moreover, a metro line connecting two airports in the Metropolitan area and Maglev express railways between Tokyo and Nagoya are in pipeline, both of which will be built in great deep underground. In the urgent situation to be taken care of, the Ministry’s official said that it is difficult to find even a temporary yard, and Tokyo Government’s official noted that all related organizations and enterprises should cooperate with each other to overcome the problem. (2013/10/10)