The G-Cans Project: Japan’s Lifesaving Underground Wonder

Japan is an island nation with mountains occupying 75 percent of the land.  That land is threaded by rivers that flow into the ocean. Japan has experienced some of the world’s worst natural disasters ,yet the amazing resilience of the Japanese people has brought about astounding engineering wonders.  One perfect example of Japanese ingenuity is the Metropolitan Area Outer Underground Discharge Channel, also known as the G-Cans Project.
Just 32 kilometers north of bustling Tokyo, deep beneath a soccer field in Kasukabe, Saitama, lies a colossal series of vertical shafts, underground tunnels, and silos that were built to protect Tokyo. The G-Cans Project began in 1992 and was only recently completed in 2009.

The Metropolitan Area Outer Underground Discharge Channel (首都圏外郭放水路 shutoken gaikaku hōsuiro), is 50 meters below the ground. The G-Cans Project is a feat of state-of-the-art civil engineering technology designed to drain water from flooded residential areas into five enormous containment silos (32 meters in diameter), and discharge it into the Edo River via connecting tunnels that stretch over 6 kilometers.  And a number of 10-megawatt pumps can pump up to 200 tons of water per second. Prior to being released, the water is first stored in a massive tank designed to avoid any possible effects caused by water pressure and force from running water. This underground structure is often likened to an underground temple.

The Metropolitan Area Outer Underground Discharge Channel is also a popular tourist attraction. Free tours are available, conducted in Japanese. It truly is an amazing architectural wonder that represents technological innovations put together from many centuries into one awe-inspiring creation.

Take a quick tour of the G-Cans Project: