Showa drainage pump station (The Metropolitan Outer Area Underground Discharge Channel)

Location: Kasukabe City, Saitama Prefecture
Discharge capacity: 200 m³/s
Number of units: 4
Type: Model-VLZGT vertical mixed flow pump

The watershed areas along the Naka and Ayase Rivers had been troubled by flooding since ancient times. This area is low-lying, like the bottom of a dish, surrounded by large rivers, such as the Tone, Edo, and Arakawa Rivers, and the rivers’ gentle gradients made it easy for water to pool.
For this reason, the Metropolitan Area Outer Underground Discharge Channel was built with the aim of reducing flood damage. This system involves directing water from the rivers when they are swollen due to heavy rain into underground tunnels for discharge into the Edo River.

The Metropolitan Area Outer Underground Discharge Channel is one of the world's largest underground flood water diversion facilities, with 6.3 kilometers of tunnels built 50 meters beneath the surface. Water taken from five rivers into massive containment silos is collected in an enormous underground tank. The water is then pumped up and discharged into the Edo River by EBARA’s four huge pumps.