Lake Life Today: Infiltration Steps
Infiltration Steps is yet another way to slow the flow of stormwater from entering our waterbodies. Infiltration steps can be used where foot traffic is causing erosion to take place, and are used where there is a moderate slope, usually less than 45 degrees. These infiltration steps minimize the potential for erosion and runoff from a footpath that is often used. As a result, infiltration steps prevent excess nutrients, sediments, and other pollutants from entering the lake.
Rainwater falling on the infiltration steps ultimately soaks into the ground and is filtered by the soil, trapping unwanted pollutants, and helping improve the overall health of our waterbodies.
Infiltration Steps are built with timbers. Geotextile fabric is anchored into the “bottom” of the step, and then backfilled with crushed stone to slow runoff and allow water to soak into the ground. Existing steps may be retrofitted into infiltration steps in some instances.
Remove several inches of soil from the location of each step.
Dispose of excavated soil in a place where it will not wash into the lake or other resource.
Line the bottom and sides of the excavated area with geotextile fabric. This fabric allows water to infiltrate through it and will separate the stone from the underlying soil.
Backfill the hole with washed 3⁄4-inch crushed stone (or pea stone) so the tread is level, or it just slightly slopes up to meet the step above. Paving stones can also be set into crushed stone to provide a smooth surface for bare feet-as long as ample crushed stone is exposed to allow infiltration, but there must be adequate spacing between the pavers to allow for the infiltration of stormwater.
To firmly secure the wooden framework, drill 1⁄2-inch diameter holes 6 inches from the ends of each timber. Then drive 1⁄2-inch diameter, 18-inch long steel rebar through the holes with a sledgehammer. For gentle slopes, wooden stakes or large rocks can also secure the timbers.
Reprinted with permission from Elaine Philbrook, LakeSmart Director for CRLA. Sources: Maine Lakes, Lakes Environmental Association (LEA)