The Katsugabe-shi area in Saitama Prefecture, north of Tokyo, has been frequently flooded with heavy rains due to the dish-shaped terrain surrounded by rivers since ancient times. Rainwater accumulated in this area has to pass through Tokyo to flow to the sea, causing damage to Tokyo.
As a project to protect the area from flood damage, the administrative authorities installed a 6.3km-long waterway 50m underground to prevent rainwater from flowing into the river at once.
Rainwater flowing in from the river is collected in a cylinder called five grains, collected in a pressure tank that weakens the flow of water, and then flows to the Edo River above ground through a drainage field.
The tank that collects water is located 22m underground, and the 59 pillars, which are 177m long, 78m wide, 18m high, and weigh 500 tons each, are reminiscent of a huge temple, so they often appear as movie backdrops or music video shooting locations.
When a certain amount of rainwater collected in five large tanks is collected, one gas turbine jet engine pumps the same amount of rainwater as the 25m swimming pool installed in the elementary school per second and sends it to the Edo River. do.
It is open as a tour course for the general public when it is not in operation except for floods.
“Drainage pumping station” is often perceived as a disgusting facility, but as the floodwaters disappeared following installing it as a “waterway outside the metropolitan area,” large distribution centers entered one following another, and visitors touring the facility. developed to attract visitors.
In addition, the above-ground part of the water tank is a multi-purpose plaza managed by Katsugabe City, which is used freely by locals as a soccer field and skateboarding ground, and is also used as a local resting place and event space.
The facility is filled with rainwater regarding 9 times a year, including typhoons and guerrilla heavy rains, and the drainage system is operated 5 times.
