Colossal Japanese Storm Sewer System
The city of Saitama Japan started construction of its colossal storm sewer system in 1992 and is now open for tours. The extensive system was built to avoid city-wide flooding during the typhoon season and is composed of giant concrete silos (65m tall and 32m wide) connected by 6.4km of underground tunnels. Extending 50m below the surface, the system also contains a giant tank that is 25.4m tall, 177m long, 78m wide and a total of 59 concrete columns.
It makes me wonder how some of this system might have been mitigated by site-specific stormwater management applied throughout the entire city. I guess it is too late to answer that one.
Source: archdaily
