These step by step instructions are designed to assist homeowners in building their private rain garden. Contractors, designers, and engineers are required to follow the specifications in the WV Post Construction Stormwater Guidance Manual (2012).
1. Location, Location, Location
Select the location for your new rain garden following these simple guidelines:
- At least 10 feet away from buildings, sheds, and patios if placed down hill from structures.
- At least 20 feet away from buildings, sheds, and patios if placed up hill from structures.
- Relatively flat ground
- Rain water will be able to get to the site
- Call Miss Utility (1-800-245-4848) to have the utilities in or near your property located. Rain Gardens should not be built where there is a conflict with your existing utilities
2. Test your soil
Perform the following infiltration test (in the image below) in the location that was chosen for the rain garden.
- Dig a 1 feet deep by 1 feet wide hole
- Place a ruler vertically in the hole
- Fill the bottom 6 inches with water and let drain. This will saturate the soil.
- Once drained, fill the hole with water again and record the height of water on the ruler. One hour later record the height of water on the ruler. Keep recording for 3 hours after filling.
3. Size your Rain Garden
To determine the size of the rain garden, consider these factors:
- How much space is available?
- How much impervious area is draining into the rain garden? Impervious area is any hard surface that prevents water from seeping into the ground. This includes roofs, driveways, patios, etc.
If plenty of space is available, the rain garden should be 5-8% of the impervious area draining to it.
Now that you know the size of your rain garden, you can lay it out and start digging.
- Prior to digging you must call Miss Utility of WV 1-800-245-4848. It is the Law.
- Remove sod and other plant material where the rain garden is to be built.
- Dig 12 inches down in the rain garden. Notice if there is rich organic dirt on top and a clay, slippery dirt down below. As best you can, divide the dirt into two separate piles.
- Use the clay dirt to create a berm on the down hill side of the rain garden.
- Fill hole with rich organic dirt.
- Place decorative stones in or around the rain garden (optional)
- Extend downspout or provide a path for the rainwater to enter the rain garden. Use stones to slow water down once it enters the rain garden.
- Plant rain garden with Native Species. See list.
- For more information on size and placement of your rain garden, see How to Calculate the Size of Your Rain Garden