Utilization of infiltration facility setting judgment map

The "Infiltration Facility Installation Judgment Map" shows whether the area can set up an infiltration facility based on topography, soil quality, and groundwater level judgment factors.
Rainwater infiltration facilities can be installed when it is determined as "possible land" in the "infiltration facility setting judgment map", but cannot be installed if sufficient separation from buildings or retaining walls cannot be secured.

1. Confirm the installation judgment of the area ("possible land", "impossible land") using the "infiltration facility setting judgment map".
2. For each installation judgment at the installation location, the following field surveys are conducted to determine whether or not the installation is final.

• a.Check the separation between the building and the outside of the crushed stone.
• b.Check the separation between the adjacent boundary, retaining wall, etc. and the outside of the crushed stone.
• c.If there is a slope or retaining wall at the adjacent boundary, check the separation according to the height.

About separation from buildings of rainwater penetration masu (PDF: 136KB)

It is a district where rainwater infiltration facilities are restricted, or a district where even if rainwater infiltration masu is installed, the function is not fully exhibited.

The judgment factors in the "Infiltration Facility Installation Judgment Map" are as follows.
Areas that are not suitable for installation based on the situation of each element have been designated as "impossible land", and other areas have been designated as "possible land".

Infiltration facility setting judgment map (PDF: 8,493KB) [April 2011 version]

Do you fall under the danger zone of steep slopes? → No installation: Dangerous areas of steep slope collapse

Is it hard to penetrate? → Not suitable for penetration: Kazusa Group (solidated silt)

Can the penetration capacity of the infiltration facility be demonstrated? → Not suitable for penetration: The groundwater level is less than 2m from the ground.