In an effort to share some best practices for non-point source pollution management, and restoration in general, we’ve created a special tutorial for you on how to build a bioswale. After planting our own mini-bioswale a couple months back, we decided to share what we’ve learned so you can plant and build one to suit your needs. Our Water Quality Specialist Ilena created the following tutorial, which you can download below. Check out the steps, pictures and tutorial below and good luck!
STEP 1: PICK YOUR SITE
A bioswale should be at least 10 feet away from your home, office or any other structures. For example, in our mini bioswale planting we located a spot near an vineyard up the hill so the bioswale could catch any potential runoff before it enters the creek.
When picking a site, keep your eye out for a low point. Typically, you should be able to spot a 1% grade slope from your driveway, parking lot or roof leading from your yard/office.
STEP 2: DETERMINE THE SIZE
Determining the size is one of the most important steps in creating your own bioswale. If you’re familiar with the area, you might think you could give it an educated guess, but we recommend you use a bioswale calculator to properly determine size and water ratios, volumes etc. The folks at Green Learning Station have a bioswale calculator here.
STEP 3: DIG!
This is the fun part when you get to dust off some tools and gloves, and work up a sweat. After determining the size and location, you’re ready to start moving some Earth. For starters, your bioswale needs to be at least 6 or 12 inches deep (and can be even deeper depending on water amounts.) The measurement of 6 to 12 inches should be measured from the top to the center of the bioswale.
When you’re digging, make sure there’s a gradual slope from the edges to the center. This will allow your bioswale to collect the rain, which will feed the plants and ultimately limit pollution, etc.
If there’s a downspout nearby, make sure it’s facing the bioswale. In fact, you can even dig a small ditch from the downspout to make sure the water enters the bioswale.
STEP 4: SELECT YOUR PLANTS
This is the step that will vary from region to region. No matter where you are, you want to fill your bioswale with native plants for the area. This will help vitalize the area you picked and promote native plants instead of those annoying invasive species like crabgrass and more. Do a little research before selecting your plants to make sure you’re filling the landscape with plants that want to survive.
The typical mix of plants includes sedges, grasses and trees to secure the area. In our bioswale we used sedges and grasses along the edges to secure the banks while planting dogwood and other “pollution eaters” in the center where the water collects. We surrounded that area with native roses and trees like cottonwood and alderwood.
STEP 5: SECURE THE SITE
This is where you’ll need some jute netting and native wild flower and grass seeds. After all the planting is complete, you can secure the area from erosion with jute netting along the bioswale edges. The jute will help prevent against erosion and keep that natural slope of the site in tact. Secure the netting with some staples and you should have a good foundation.
One the netting is secured you can spread wild flower and grass seeds within the area. This will help to promote native plants (like the step before) and hopefully keep out that invasive crabgrass and more.
Once you’ve completed that step, you’re done! With a good team, you can learn how to build a bioswale and have it planted and ready within a few days time.
Don’t forget to download our How To Build A Bioswale Handout here.