7. Design Principles of Rain Gardens
• Handles stormwater at its source.
• Decreases the velocity of water flowing from
• Improves water quality before it enters the stream
• Facilitates infiltration
8. Rain garden benefits
•Add beauty (and value) to your property
•Minimizing rainwater runoff to storm drains or streams while
allowing excess rainwater to filter slowly into the soil
•Protecting our valuable water resources
•Provide wildlife habitat
•Adaptable in scale and land use
9. Match $$$ provided by involving
County Extension Agents
$ matching funds to
you, aren’t I?
10. Garden Location & Installation
Observe your yard during a rainfall event
• Where does water
travel or collect?
11. Rain garden planning
•Source and path of stormwater
•Size of impervious surfaces
•Soils type (sandy, clayey, rocky or mixed)
•Proximity to wells, foundations, septic systems
•Existing landscape features
22. Summary of Preliminary Analysis of Raingarden Condition.
Rain gardener Type Rain garden Condition*______
Good Fair Failure
Avid 10 3 1
Environmentalist 2 7
*Good: Maintained well,
Connection 4 4 functioning as designed.
Fair: Maintenance not
Flooding 2 3 evident, still provide some
Failure: Not maintained, not
Required by functioning.
Law 8 15 8**
Schools 1 5
23. Rain Gardens Maintenance Issues 2 Years after Installation.
Maintenance Issue Number of Rain gardens Affected
Berm / Weir Failure 6
Plants / Planting 49
Soils / Drainage 10
Sedimentation / 8**
General Neglect / Abandoned 9
Mitch Woodward, Area Specialized Agent [email_address] Wake County 4001-E Carya Dr Raleigh, NC 27610-2914 (919) 250-1112
When rain falls on a natural environment it can either soak into the soil or it can runoff into the surface water. The remaining percent of rainfall is intercepted by trees, crops, grass, and other ground cover that serves to dissipate much of the energy contained within each raindrop. The water can then re-evaporate back into the atmosphere, or slowly infiltrate into the ground. The infiltrated water eventually reaches groundwater, which slowly travels through the soil back into local waterbodies. As the water infiltrates and flows, it is cleaned of any pollutants it may have collected along its journey from the atmosphere into the ground. Unfortunately, with increased urbanization, the rain encounters more and more concrete and other hardened surfaces which do not allow for infiltration of water into the soil.
Rain gardens vary in shape and design. The options are numerous with lots of plant varieties that can be incorporated.
The benefits of a rain garden are numerous!
Look around your yard for low areas where water may collect after big storm events.
Rain gardens work best when constructed in well-drained or sandy soils, but they can also be installed on sites with less permeable soils such as clays. By digging a hole at the rain garden site, the soil can be examined.
Fill a hole with water to observe infiltration. If water does not drain within 2 days of no rainfall, a backyard wetland may be best.