首都圏外郭放水路 - Shutoken Gaikaku Hosuiro

Metropolitan Area Outer Underground Discharge Channel - G-Cans Project


Useful Information

Location: Kasukabe, Saitama Prefecture. 2nd floor at Ryukyukan, Showa drainage pump station (Reception).
Open: All year Tue-Fri 10, 13, 15.
[2012]
Fee: Free.
[2012]
Classification: ExplainSewage System
Light: electric
Dimension: L=6,300m.
Guided tours: D=90min.
Photography: allowed
Accessibility: The staircase into the tank has 100 steps
Bibliography:  
Address: Metropolitan Area Outer Discharge Channel Tour, 720 Kamikanasaki, Kasukabe city, Saitama 344-0111, Tel: +81-48-747-0281.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.

History

1993 project started.
2002 tunnel ready for use.
JUN-2006 system in full operation.

Description

The Tokio Sewer system is an impressive series of vast underground chambers and vaults. The climatic conditions require enormous sewers to drain the huge amounts of water rainfall might bring. The eastern part of Saitama Prefecture has always been prone to floods. The flood control system is actually separated from the normal sewers and does not contain waste water. It is intended to swallow floods, store them for some time and then release the water controlled into rivers. It also allows the transort of huge amounts of water from one part of the city to another.

The operator of the whole sewer system is the government, or better the Edogawa River Office under the Land, Infrastructure and Transport Ministry. They now offer regular public tours into the flood control tunnel in Kasukabe, Saitama Prefecture. The 6.3km long conduit is located 50 meters below national road 16 and connects the Otoshifurutone and Edo rivers. If the Otoshifurutone River or the nearby Naka River flood, the excess water may be channeled into the tunnel from five different locations. It is stored in an underground chamber and released into the Edo River over the next days.

The huge water chamber called underground palace or underground temple is big enough to store 670,000m³ of water. The 25m high ceiling of the chamber is supported by 59 columns.

The tour is actually not a tourist venture. It is a public service to give citizens a chance to see how their millions were spent. And while they have an English website, they offer tours only in Japanese. For security reasons it is necessary that visitors understand the guides, so visitors who do not speak Japanese must bring someone to translate. And as it is a working facility, there are several restrictions. Obviously the place may not be visited in the weather conditions which might result in a flood. The tours are held on workdays only and children under five are not allowed, children under 16 must be accompanied by an adult. It is alsi necessary to be there at least 30 minutes before the tour starts for the security instructions.