Page 38 - 7166 - Rain Garden Handbook

Build
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Excavate

Before digging, determine the depth of excavation necessary to accommodate
the ponding depth, soil mix depth, and overflow containment area.
Recommended ponding depth is 6 inches or 12 inches. Recommended overflow
containment depth is 6 inches minimum. Recommended rain garden soil mix

David Hymel depths are 12 to 24 inches. Examples for determining excavation depth are
provided for each of the three rain garden soil mix options below. Refer to page
24 for a typical cross section showing rain garden excavation depths.

Rain Garden Soil—Three Options

There are three options for providing rain garden soil. Instructions about how to
choose one of these options are provided on the following pages.

OPTION 1. Excavate and Replace Soil: Excavate the soil and completely
replace with new rain garden soil mix.

OPTION 2. Excavate and Amend Soil for Reuse: Excavate the soil, amend
it by mixing in compost, then put it back into the rain garden.

OPTION 3. Amend Soil in Place: Amend your existing soil in place by
mixing in compost after you've excavated to the proper depth.

Many Hands Make Light Work

If you are digging a small rain garden that’s not very deep, digging by
hand with friends may work well. If you’re installing a bigger rain garden,
consider renting a mini-excavator. The ground often gets more dense and
harder to dig the deeper you go.
Jason Martinelli