• I picked up a copy of a report from the architecture firm BNIM this week on the effectiveness of the rain garden outside of the Ambler Student Recreation Fitness Center.

The whole point of a rain garden, the report reminds us, is that it reduces water runoff. The rate from the runoff from the roof of the building is slowed to reduce the potential for downstream flooding and stream bank erosion.

Plants were installed in May 2009 and “appear to be thriving,” the report said.

When it’s dry, the garden can delay the water runoff by about an hour and 20 minutes, which is “a significant reduction over expected travel times through pipes,” the report said.

The garden also disperses the water runoff over a large area to reduce the possibility of erosion.

Jeff Severin, KU’s sustainability guru, explained a bit about the project in a Journal-World article from 2010 that commemorated the garden’s first anniversary.

“It’s basically a depression that can collect that initial flush of rain water,” Severin said at the time. “They’re typically designed with native plants and other kinds of tolerable species that can also help filter any pollutants in that water. So basically it’s an urban storm water management tool that people can use in their yards on a small scale or, in the case of the campus garden, can be used in a pretty large scale. Ours is kind of different because it’s huge.”