Slow it, spread it, sink it

We wanted to share this great video by the US Environmental Protection Agency that shows a number of ways to reduce stormwater runoff including rain gardens, rain barrels and green roofs. Many of these best practices can be used at your home. The goal of these tools is to 'slow, spread and sink' the stormwater to keep it from polluting downstream waters.

Constructed wetlands

"S" shaped constructed wetland

At the headwaters of Frenchman's Creek in Dartmouth, a wetland was constructed to treat stormwater runoff from the adjacent sports fields and parking lot. The wetland has a serpentine shape and varying depths in order to maximize residence time of the runoff in the wetland. This allows for increased removal of nutrients and metals through plant uptake and adsorption. This stormwater treatment feature essentially acts as a kidney purifying the water. The runoff leaving this site now enters the natural environment at a much higher quality than it would if directly released without treatment. 

This wetland would require occasional maintenance to maximize function. Construction was done by Jeff Pinhey and Rob Leblanc in 2007. 

The marsh is predominantly vegetated with cattails

Rain Gardens

Rain garden constructed by Clean Annapolis River Project (www.annapolisriver.ca)

Rain gardens are small, landscaped areas that capture, filter and infiltrate rainwater.  Rain gardens can create an attractive detention area where runoff can slowly soak into the ground, be taken up by plants and return to the atmosphere through evapotranspiration. Planted with water-tolerant native plants, rain gardens can become a beautiful and functional feature on your property.

Rain gardens allow at least 30% more water to infiltrate into the ground, compared to a conventional lawn (source). They can help recharge groundwater resources, reduce stormwater volumes and create habitat. Rain gardens are relatively easy and inexpensive to design and build. Just keep in mind a few important considerations when deciding where and how to install a rain garden on your property:

-Observe how stormwater naturally runs in your yard. Place the rain garden at a low point or elsewhere along the natural flow path.

- Maintain at least a 1% slope from the impervious surface to the garden. 

- Rain gardens should be located approximately 3 m away from a building to avoid drainage problems on your property.

-Clay soils don’t allow for proper drainage, therefore look for a place with soil that is sandy, gravelly, loam or a mix. If your soil has a high clay percentage, you can add sand, fine gravel and/or organic matter to improve permeability.

- The surface area of a rain garden should be 20-30% of the roof/parking lot area it drains.

- A general guideline for rain garden depth is 7.5 cm in soils with relatively low infiltration rates (i.e., loam) and up to 15 cm in soils with high infiltration rates (i.e., sandy or gravelly soils).

-  A downspout can empty directly into a rain garden. Just add some stones or a splash pad to prevent erosion.

Rain garden (Photo CMCH: bit.ly/dCOkur)

Some really helpful tips on installing and maintaining rain gardens can be found from the Canadian Mortgage and Housing Corporation's factsheet 'Improving Stormwater Management in Your Yard'.  

More great information on rain gardens, including a list of native, water-loving plants, can be on the Clean Annapolis River Project website. 

Do you have a photo of a rain garden or maintenance tips that you'd like to share? We'd love to see them! 

Beautiful! (Photo: www.atlantic.sierraclub.ca)