Central Japan Railway Co said Thursday it has temporarily halted construction work on a new high-speed maglev train line between Tokyo and Nagoya after water and bubbles appeared from the ground in a residential garden near a tunnel digging site in western Tokyo.
The residence in Machida is near a site where excavation is being carried out over 40 meters beneath the surface to build a tunnel for the Linear Chuo Shinkansen project.
The construction company reported to JR Central on Oct 22 that a resident noticed water coming to the surface, which was later confirmed by an official of the railway company. The water and bubbles continued until Oct 24 but have since stopped.
The machine used in tunnel excavation releases a foaming agent containing surfactants to make soil digging easier. Tests on water sampled from the garden showed surfactant levels within drinking water standards.
"We are investigating the cause and will continue to monitor conditions in the surrounding area," a JR Central official said.
The Linear Chuo Shinkansen will connect Tokyo, Nagoya, and eventually Osaka, with trains traveling up to 500 kilometers per hour.
The tunnel beneath the greater Tokyo area will stretch 37 km, linking Shinagawa Station to a planned station in Sagamihara, Kanagawa Prefecture. Its construction is divided into four sections, with tunneling being conducted in each.
The prefectural government in Shizuoka has recently approved a boring survey in preparation for the maglev train line's construction, amid concerns the geological survey ahead of tunnel drilling could reduce water flow in a river in the prefecture.
