A Rain Garden
August 9th, 2007
The garden next to the parking lot at West Hanover Twp.’s Fairville Park doesn’t look like anything special.
It appears to be your basic wildflower garden with a mix of familiar brown-eyed susans, purple coneflowers, red beebalm and grasses.
Don’t be fooled.
This oblong, 20-by-28-foot patch is a flood-preventing, water-filtering, pollution-cleaning, well-recharging, bird-feeding, butterfly-attracting machine.
And it’s pretty, too.
In short, it’s a rain garden and one of the Harrisburg area’s earliest and most visible examples of what should be in every one of our yards.
Rain gardens are areas that have been dug up and retrofitted with well draining soil topped with about 6 inches of mulch.
They’re located where rainwater drains, they’re graded like shallow saucers, and they’re planted with plants that don’t mind occasional “wet feet.”
“What we’re trying to do is direct water into an area where it can soak into the ground,” says Carol Buskirk, a member of West Hanover’s Environmental Advisory Council, which planned and built the Fairville Park rain garden.
“Water going back into the ground replenishes the water table,” she says. “Going through the plants and through the ground cleans the water. It’s a biological way of filtering water.
“Rain gardens also lessen flooding. They’re attractive. And they attract birds, butterflies and hummingbirds.”
Patti Estheimer, chair of the Environmental Advisory Council, says rain gardens basically do what forest floors do in nature — they capture rain instead of let it run off-site.
“This is a great way to do that, and it’s a really pretty way,” she says. “This isn’t a big hole that just sits there.”
Unlike deeper, grassed detention ponds that are common in housing developments, rain gardens are only 6 inches at their deepest point. They’re built so that rainwater soaks in within a day (usually within a few hours), eliminating mosquito and other standing-water concerns.
The Fairville Park rain garden is a perfect example of where and how they work.
The park’s sloping parking lot had been channeling rain off the back right and down a short but fairly steep bank.
“All the water was running down that hill, and we noticed we were getting ruts,” says Estheimer.
With technical assistance from the Alliance for the Chesapeake Bay and a grant from the state Department of Conservation and Natural Resources, the committee and two dozen volunteers built a rain garden around the hill in the spring of 2006.
First, soil was excavated to a depth of about 18 inches. Then the hole was filled with about a foot of topsoil heavily amended with compost. Six inches of mulch went over the top, and the remaining topsoil was used to build a small berm around the perimeter.
All native plants were used to plant the garden.
Drier-soil species were used around and closest to the perimeter, such as purple coneflowers, creeping sedum, creeping phlox, wild blue indigo, low-bush blueberries and switchgrass.
Toward the middle where the garden will stay wetter longer, damp-tolerant species were used. These include great blue lobelia, swamp milkweed, New England aster, goldenrod and blazing star.
To break the rush of water during heavy rains, a pair of rock channels were laid in the hill. These turn into small cascading waterfalls when it rains.
A small rock spillway was added at the far end of the garden, “in case we have so much water that it doesn’t drain fast enough,” says Estheimer.
So far, this rain garden has worked like a charm.
“We were concerned about how much water can come off that parking lot,” says Estheimer, “but it’s worked perfectly.”
“It’s amazing,” says Buskirk. “I’ve been out here when it’s raining, and those waterfalls are just gushing. The garden fills up, but then the water percolates down into the ground.”
I paid a visit to the rain garden the morning after an inch rainfall overnight, and the water was gone. The middle of the garden was slightly soggy, but there were no puddles and no washouts.
That storm’s parking-lot drainage was completely sucked up by the rain garden. The water didn’t go into any streams or storm-sewer systems, and it didn’t contribute to any flooding downstream.
Better yet, oil and gas leaks from the cars and any other pollutants on that parking lot didn’t make it into any waterways.
The beauty of the garden is almost a bonus.
Kids and parents using the nearby playground equipment now have a flower garden to look at instead of a weedy, rutted bank, and numerous birds and butterflies can be seen all over the wildflowers.
The whole idea makes so much sense that it’s a wonder we’ve opted instead to pipe water off our roofs and direct it off our driveways and parking lots into storm-sewer systems.
Estheimer says few people know what a rain garden is, which is why the Environmental Advisory Council decided that building one in a prominent public spot would be a good educational move.
The Keep Pennsylvania Beautiful program thought so, too. It awarded this garden one of its Community Greening Awards last September.
“We’re really trying to encourage developers to do this rather than the standard storm-water basin,” Estheimer says. “Water is a big issue in Pennsylvania. Our water isn’t getting any cleaner. And in developments, we’re still directing water off the property. As much water as we can keep on a piece of land, that’s what’s going to make a difference.”
More gardens are always nice, too.
Where rain gardens make sense
Rain gardens can be added to any home to keep rainwater on your property while adding colorful and wildlife-friendly plantings in place of lawn.
Two logical spots on most home lots: where water is draining out of down spouts and where water is running off paved surfaces such as driveways and patios.
Rain gardens should be located at least 10 feet away from houses to avoid creating moisture problems in the basement. Spouts can be shallowly buried if you want grass between the house and rain garden, or you can build a narrow rock channel to carry water from the spout to the garden.
Rain gardens need only be 4 to 6 inches deep in the middle when you’re done, but the key is replacing packed soil with about 18 inches of well drained soil and mulch.
One good formula for the soil is 20 percent compost or decayed leaves, 50 percent sand and 30 percent of your excavated soil. Figure on topping that with 4 to 6 inches of wood mulch.
Size also is important. The garden ideally should be about the size of the roof area or surface area being drained.
Plants are typically arranged in three zones. The most wet-soil-tolerant ones go in the middle of the rain garden, the dry-soil ones go around the perimeter, and ones that can take a little of both go in between.
West Hanover Twp.’s Fairville Park is one good example of a homeowner-sized rain garden.
There’s also one beside the Kramer, Shirley, Ditty and Marfizo dental office at 4002 Linglestown Road, Lower Paxton Twp., and three larger ones off the parking lots at the west side of Harrisburg Area Community College’s Wildwood campus.
More information on rain gardens and how to build them:
* A free 32-page, downloadable rain-garden how-to manual from the University of Wisconsin Extension at http://clean-water.uwex.edu/pubs/pdf/rgmanual.pdf.
* Rain Gardens of West Michigan web site at www.raingardens.org.
* Rain Garden Network web site at www.raingardennetwork.com.
Native American plants that make good choices for use in a Pennsylvania rain garden:
* WETTEST ZONE
Blue flag iris
New England aster*
New York aster
New York ironweed*
(plants with asterisk afterward also work in the middle zone)
* MIDDLE ZONE
Great blue lobelia
Green and gold
New Jersey tea
New York fern
Red osier dogwood
* TRANSITION ZONE
Great blue lobelia
Green and gold
New Jersey tea
— Sources: Alliance for the Chesapeake Bay, Penn State Extension
Want to take a look at the Fairville Park rain garden in West Hanover Twp.?
To get there from Harrisburg, take I-81 north and get off at the Route 39 and Manada Hill/Hershey exit.
Turn left off the ramp, pass the truck stop and take the first right onto Fairville Avenue at the Comfort Inn.
Go 1.3 miles and go straight at the 4-way stop with Moyer Avenue.
Go another one-half mile and turn left into the park entrance. The rain garden is off the back right of the parking lot.