rain gardens

Another Win for Rain Gardens

By Amanda Ryan

Originally published by the Center for Land Use Education and Research

aerial image of retention pond in residential neighborhood
Image of retention pond from Activerain.com

It’s well known that rain gardens are great for infiltrating stormwater but people may not realize that they also help destroy common stormwater pollutants. Several studies have found that rather than accumulating pollutants in their soils, rain gardens tend to biodegrade them instead. One study (LeFevre et al., 2011) investigated petroleum hydrocarbon levels in 58 rain gardens in Minneapolis, MN representing a wide range of sizes, vegetation types, and contributing area land uses. The researchers found that petroleum hydrocarbon levels were well below regulatory limits in all the rain gardens sampled. And a tip for future rain garden installers, rain gardens planted with more robust vegetation with deeper roots did a better job at breaking down pollutants than those planted with only turf grass.

A rain garden’s ability to biodegrade pollutants is in contrast to what happens in more conventional stormwater management structures like retention ponds. Retention ponds are often installed with larger developments to receive a large volume of stormwater from impervious areas (ex. houses and roads in a subdivision, roof and parking lot of a Home Depot). Other studies (Van Metre et al., 2009; Van Metre et al., 2000; Kamalakkannan et al., 2004), found that pollutants like PAH’s (polycyclic aromatic hydrocarbons), a type of petroleum hydrocarbon, accumulate in the sediments of stormwater retention ponds. This creates a very expensive maintenance issue for retention pond owners when the time comes to remove and dispose of built up contaminated sediments.

Side note – stormwater can pick up PAHs from dust on pavements treated with coal tar  sealants which are commonly used on parking lots, driveways, and playgrounds (but they have recently been banned from use on State and local highways in CT).

If by now you’re energized to install one or many rain gardens on your property, check out NEMO’s  rain garden site and Rain Garden App!

Touring UConn’s Green Infrastructure – From Your Desk!

Anyone who has been to the UConn campus in the last few years has likely noticed a lot of changes. Beautiful new and renovated buildings are remaking the campus. Along with those changes are a lot of more subtle changes that you might not notice – namely the integration of green infrastructure.

As discussed in previous posts, green infrastructure refers to using nature and natural processes to deal with infrastructure issues like stormwater. It includes such practices as bioretention/rain gardens, pervious pavements, and green roofs (among others). UConn has become a statewide and national leader in implementing these practices.

To highlight some of UConn’s efforts and demonstrate how to integrate these practices into an urbanized/urbanizing community, we created a virtual campus tour using Esri’s Story Maps tool in AcrGIS Online. (Story maps, by the way, are an extremely slick and easy way to bring your data or information to life in a geographic context. Definitely worth checking out.)

Take the tour by clicking on the image below:

green roof