Page 30 - 7166 - Rain Garden Handbook

24 PLAN
1

INFLOW

Rain Garden Terms

TOP SURFACE OF PONDING AREA
• This is the level that water will rise to
before overflowing out of the rain garden.
• Multiply the sizing factor from the Rain
Garden Sizing Chart by the contributing
area to calculate the top surface of
ponding area.

OVERFLOW CONTAINMENT AREA OVERFLOW
• The overflow containment area provides
extra ponding depth in case the overflow
becomes clogged with leaves or other debris.
It will help direct water to the overflow,
particularly after a period of heavy rainfall PLAN VIEW
when more water flows into the rain garden.

• Overflow containment should be a Dimension of Overflow Containment Area
minimum of 6 inches higher than the Dimension of Top Surface of Ponding Area
top surface of the ponding area.
Dimension of Top of Rain Garden Soil Mix
OVERFLOW
6-INCH PONDING DEPTH IN OPTIONAL
• Typically will only flow after a big storm. THIS EXAMPLE BERM
• If your rain garden has a berm, the overflow
will cut through the berm in a depression 2:1 SLOPE MAXIMUM
that slopes out from the ponding area. 6”
• The overflow must direct water to a safe 12” to 24”
location (e.g. open space, roadside swale, Recommended Rain Garden Soil Mix
OVERFLOW WILL
or storm drain). Do not direct overflow DRAIN WATER IF LEVEL
towards adjacent properties or structures. PONDING DEPTH CAN BE Bottom of Excavation/Top of Existing Soil RISES ABOVE TOP
6 INCHES OR 12 INCHES SURFACE OF PONDING
SECTION VIEW