Published Oct. 13, 2013, in the Wyoming Tribune Eagle, “Rain gardens solve problems: All of that runoff that surges into storm sewers—and sometimes basements—could be diverted into a basin for your garden’s benefit
By Barb Gorges
Rain garden. It brings to mind splashy flowers seen from under the protection of an umbrella.
It doesn’t sound like something that would be close to relevant in Cheyenne, unless we have regular repeats of our soggy September weather. Those 6.95 inches (second wettest month on record) wouldn’t be considered much in Ketchikan, Alaska, (153 inches annually) or even New York City (49 inches). But it is here, where the annual average is 15.90 inches.
Wouldn’t it be nice if we could sock away moisture, even from brief cloudbursts? Wouldn’t it be nice if it didn’t just run down the street and back up the storm sewer? Or run into your basement?
Nancy Loomis—who co-owns Antiques Central with her sister, Pam Loomis—was having problems with storm water getting into the basement of the store at 2311 Reed Ave. A few years ago, she read a magazine article describing rain gardens. She learned they are a way to capture snowmelt and rainstorm runoff from impermeable surfaces, like roofs and pavement. These gardens hold the water temporarily so it can percolate into the ground. This recharges the groundwater, even more effectively than your basic lawn.
The city of Cheyenne has done something similar, creating basins for runoff, sometimes known as bioswales if they are designed to filter silt and pollutants. The one between Warren and Central avenues at Pershing Boulevard, called Pando’s Pond, is the most noticeable. But no one is calling it a rain garden.
A rain garden is small, less than 300 square feet. It takes advantage of the additional moisture it receives to grow a variety of blooming plants, usually without the aid of additional irrigation—even here.
Have you ever noticed, while driving two-lane highways in Wyoming, how much greener the grass is near the shoulders of the road compared to as little as 10 or 15 feet away? Runoff from the pavement provides that much more moisture.
Nancy’s problem is that rainstorms and snowmelt cause her street to flood and back up into a loading ramp sloping below grade level, leading into the basement. Some of that water was coming from the roof of her building.
So Nancy dug her first rain garden, about 10 feet out from the building. Its size is based on a calculation of the size of the section of roof at one downspout, the infiltration rate of the soil and the amount of water in an average Cheyenne rainstorm. To it, she later connected a second garden.
Not only did she need to dig a 10-inch deep basin, but she had a mound of dirt to remove also. She admits it was a little crazy to be doing it by hand, hauling 5-gallon buckets away to the city compost facility, but she found some interesting historical objects and a nice block of granite. She learned much about her dirt she wouldn’t have if someone else had done it with heavy equipment.
Plants for the rain garden need to be chosen from three categories, beginning with those that would be planted on the flat bottom that could have their “feet” wet for up to three days (longer would breed mosquitoes), though ideally it would only be for 24 hours. Even during the worst of the September storms, Nancy’s rain gardens drained in three to four hours.
For the lowest level, Nancy chose Saskatoon serviceberry, “Blue Creek” and “Dappled” willows, currant, Joe-Pye weed, Siberian iris, hardy pampas grass, spiderwort and Japanese iris.
On the lower sides of the basins are plants that enjoy extra moisture but not a soaking: roses, butterfly bush, daylilies, tall garden phlox, daisy, columbine, cranesbill, summer onion, Jupiter’s beard, bee balm, Maltese cross, candy tuft, hardy hibiscus and asters.
On the uppermost sides, and the top of the berm, are the plants that prefer more xeric conditions: Russian sage, Oriental poppy, agastache, salvia, cat mint, and aster. She chose cultivars that suit our cold hardiness Zone 5, often selecting for colder Zone 3 or 4.
Nancy did irrigate her new plantings, but by the second season, they were on their own. Some plants are self-seeding or self-generating, growing into areas where the moisture level suits them.
Across the front of the building another garden gets watered by shovel—snow shovel, that is. The extra moisture from clearing the sidewalk by dumping the snow onto the garden means it doesn’t need irrigation, even as late as mid-August, when I visited.
Nancy was able to get a grant through the Wyoming Department of Environmental Quality to make this a demonstration rain garden. If you visit, you can pick up a flyer from a box which explains how the Historic Sunrise Rain Gardens Project (the building originally housed the Sunrise Creamery) was built and gives a list of resources and suitable plants.
While DEQ grants are available for non-point source pollution projects (roofs and roads are dirty and rain gardens can provide filtering to clean up the water before it hits the aquifer), those grants are designed primarily for bigger projects than what the typical homeowner needs.
But the Laramie County Conservation District can help you plan your rain garden: figuring best location, ratio of roof to depth and size of the depression, cost of excavation, need for gravel filter layer, location of overflow outlet, etc. Water specialist Matt Ley is the person you want to talk to.
Twenty years ago, I discovered county officials were interested in what it took to move flood waters out of the county as fast as possible, even if it meant channelizing our two local creeks within the city. The idea of capturing the moisture has slowly taken over. Matt would like to see vegetation added to our municipal basins to add an additional layer of filtration. Wouldn’t it be fun if what currently looks like giant soccer fields on East Lincolnway turned into gardens, even bird habitat?
Nancy said planning was the most time-consuming aspect of the project. The actual digging and planting only took a couple of weekends.
Flooding from the street is still a problem at her corner. A neighboring business recently paved its gravel parking lot, creating more runoff. Perhaps when the day comes when flooding also affects neighboring businesses, the owners can come over to find out what Nancy’s rain gardens are all about: the beauty of utility.
Rain garden resources
Historic Sunrise Rain Gardens Project, educational demonstration, 2311 Reed Ave.
Matt Ley, water specialist, Laramie County Conservation District, 772-2600.
Rain Garden Design Site and Selection Guide, University of Nebraska-Lincoln Extension, an interactive guide, http://www.extension.unl.edu/web/extension/publicationsandapps.