Page 62 - 7166 - Rain Garden Handbook
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56 Maintain Keep the Minimize Exposed
Water Flowing Soil and Erosion
After heavy storms, check the inflow and overflow Sediment flowing into your rain garden can clog the soil mix and slow
areas to make sure they are still intact and can drainage. Sediment carried out of the rain garden can harm streams
continue to carry water into and out of the rain and wetlands in many ways, including transporting pollutants,
garden. Remove any debris or litter in the rain covering fish spawning areas, and filling stream channels and pools.
garden that may interfere with flow. Keep the To guard against soil erosion problems:
inflow pipe accessible and flush out pipe if
necessary. Look for areas where water may not • Check the rain garden for areas of exposed soil, particularly in the
be soaking into the ground. This may be due to fall before the wet season begins, as well as during the winter.
fine sediment or compaction of the soil. Remove • Replenish mulch areas throughout your rain garden—on the sides
sediment that may be building up and rake the and bottom of the rain garden and also around the perimeter (and
soil surface. If you suspect compaction, break up on the berm if applicable).
and loosen the soil when it is not saturated.
• Maintain a healthy cover of plants.
• Maintain a decorative cobble rock pad to protect the ground and
prevent erosion where concentrated water flows into the rain
garden from a pipe or swale.
• If sediment is deposited from water entering the rain garden,
immediately determine the source and stabilize the area.
• If there is a localized area of erosion, consider stabilizing the area
with rocks to spread out the flows causing erosion. If there are
already rocks in this area, use larger rocks or cover a larger area
with rock to spread out the flow.
• If erosion is occurring at the inflow and overflow locations, you may
need to extend the cobble rock in these areas to disperse water flow.
• If erosion persists, water may be flowing into the rain garden too
rapidly, In this case, the slope of the pipe or swale directing water
may need to be reduced, or the amount of water flowing into the
rain garden may need to be decreased. Adding small rock check
dams every few feet in the inflow can slow water and reduce erosion.
Michael Carey
