Calculations and Design Photo by The City of Maplewood, Minnesotaĭesigning a rain garden to handle all of the runoff from a roof or driveway entails careful calculations. Instead, pick an area that dries out quickly. Although a low spot in the yard might seem an ideal placement, if it stays soggy, it's already saturated.
Rain gardens are appropriate drainage spots for steeper slopes than swales can handle, but where the surface drops more than 3 feet over a 15-foot horizontal distance, you should get professional design help. Runoff may flow into a rain garden from a swale or pipe, or may simply run in from a sloping yard. A fast-draining soil mix encourages water to sink in and promotes lush plant growth. Where a swale is mostly a travel route for water, a rain garden is a destination. Shallow catch basins planted as flower beds, rain gardens allow water to pool during a downpour, then slowly percolate into the soil. Rain Gardens Photo by City of Maplewood, Minnesota Top the gravel with at least 8 inches of a compost-rich soil mix.Īdd a Drainage System Under Raised Decks Backyard Drainage Solutions 2. If the swale itself can't be made big enough to handle all the water, consider excavating another 6 to 8 inches, lining the trench with filter fabric, laying perforated pipe, then covering it with round ¾-inch gravel. Where drainage is slower still, replace soil with 60 percent screened sand and 40 percent compost. If water sinks in half that fast, amend it with 40 percent compost. If your soil drains quickly (at least ½ inch per hour), it can just be loosened. The sides of the swale should flare so they extend out three to four times more than they are tall, and the first 8 inches of soil should drain well. Consult a landscape contractor or a civil engineer if you live near a bluff, have a septic tank nearby, or are on a slope that drops more than 1 foot over a horizontal distance of 20 feet.Ī swale should carry water to a place where it can be released safely, such as a garden bed with good drainage or a buried dry well allowing it to be absorbed on-site, rather than flow into a storm drain, is important for protecting natural waterways.
You can build a small swale yourself, but for a long, wide one you'll want to hire a pro with earth-moving equipment.
Rugged prairie plants or other natives that are at home in fast-draining soil are another option. Along the sides, she uses evergreen ferns, sedges, winterberry, grasses, and Siberian and Louisiana irises that thrive in moist conditions. Jan Johnsen, a landscape designer in Mount Kisco, New York, often landscapes swales by lining them with river rock. The addition of a perforated pipe laid in gravel underneath can help handle heavy water flow.Ī small swale might carry gutter water from a house to a dry well, while a more substantial one could run along the base of a hill above a low-lying house to divert water around it. Plants on a swale's gently sloping banks-and sometimes down the center of the channel itself-take up much of this water. They filter runoff along the way by allowing it to sink into the soil. Swales are depressions that follow the contour around the base of a slope (natural or created), channeling storm water from one place to another. Here are 3 drainage systems you can create in your landscape and yard: 1. “You can cure your wet-basement problem and do something for the environment at the same time,” says This Old House landscape contractor Roger Cook. Plus, they allow pollution, including oily residue from cars, to filter out naturally, so it doesn't wind up in lakes or streams. Since these yard drainage ideas allow storm water to sink into the soil gradually, they help reduce flooding. And driveways, patios, and walkways can be constructed of pervious paving that never puddles because water seeps through. Gutter water can flow into rain gardens that provide a habitat for butterflies and birds. Ditches can be landscaped as swales that look like creek beds or small meadows. You can turn landscaping for water drainage solutions into features that enhance your yard-and protect natural waterways.