KANSAI PORACON provides nature- and environment-friendly products ofrainwater penetration, including penetration inlets, penetrationgutters, penetration manholes, and catchment gutters.

Results of Follow-up Survey for Rain Runoff Control Effects

[Location]
3 Tsutsujigaoka, Akishima City, Tokyo; Development area: Approx. 27.8 ha; No. of houses built: 2673

[Geological outline]
2.5 m underground from the earth's surface: Loamy layer of the Kanto Plain; Deeper than 2.5 m underground: Gravel layer; Groundwater level: About 10 m

[Survey results]
Rain fell on August 22 and 23 of 1981 - Rainfall amount: 87.5 mm; Rainfall hours: 30 hrs.
Total rainfall runoff amount in an area with normal sewage pipes are installed: 327.7 m3/ha
In an area processed with the underground penetration technique applied: 22.0 m3/ha
(Total runoff reduction rate: 93%)
The peak runoff was significantly decreased, while a delay was observed in the time between the beginning of rainfall and rainwater runoff. (Shown below)