Page 18 - 7166 - Rain Garden Handbook

12 PLAN Where to Locate
1

a Rain Garden

DO LOCATE YOUR RAIN GARDEN WHERE: GUIDANCE FOR LOCATING RAIN GARDENS

• It improves the appearance of your home. Rain gardens NEAR OR ON SLOPES
can provide attractive visual buffers from roads or If you want to place your rain garden near or
neighboring homes. on a slope greater than 10%, have a qualified
• You have enough space (see guidance for sizing your geotechnical engineer evaluate the site for
rain garden on page 18) and in a place that will not be potential problems. Collecting and allowing water
used for other purposes in the future (such as a reserve to soak into steep slopes can cause instability
drainfield area). and possibly landslides.
Michael Carey • The overflow can direct water safely away from the home CALCULATING SLOPE
and neighboring property.
• Water flows to the garden by gravity. Slope is typically described in degrees or percent.
When using percent, calculate the rise (vertical
Be sure to check local city or county requirements that may distance) divided by the run (horizontal
apply to your rain garden project, including the need for distance) and multiply by 100.
any permits or approvals.

Rise (Vertical Distance)
Slope =
Run (Horizontal Distance)
2 ft Rise
Example: Slope = = .10
20 ft Run

To convert decimal to percent, multiply by 100 and
include the % symbol: .10 x 100 = 10%
The easiest way to multiply by 100 is to move the
decimal point two places to the right.

* Consult a geotechnical engineer if the slope is 10% or more.
Run: Horizontal Distance

Rise: Vertical
Distance
Mandi Roberts Mandi Roberts