by Rachel Hamowitz

Of all the things that cross your mind when building a new home or business—location, financing, architecture, interior design, permits, etc.—I’m willing to bet that stormwater retention is pretty low on your list of concerns. In a world of televised hurricanes, tornadoes, wildfires and earthquakes, a little excess rainwater probably doesn’t sound like a serious problem. But the damage done by stormwater runoff can be dramatic: flash floods, crop failures, home destruction. It can also be insidious: erosion, soil contamination, water pollution, aquifer depletion. In some areas, as much as 70 percent of surface-water contamination is caused by stormwater runoff carrying everything from gasoline to nitrates to plastic bags into our rivers and lakes.
Unfortunately, every time you remove an area of natural drainage by paving over a forest or field, you contribute to the problem. Fortunately, there are several excellent solutions that the conscientious (or at least law-abiding; Oregon rarely permits people to discharge raw stormwater into surface water) home or business owner can employ.
The average yearly rainfall in Oregon is 27.4 inches—certainly enough to soak your toes, and also enough to do significant damage to your property without proper management. You could always install a detention basin—typically an ugly, pipe-infested depression in the ground where excess rainwater is collected until it can flow, largely unfiltered, to the local aquifer or body of water—but who wants to look at that every day? Instead, explore one of the following options, presented in order from solutions for the Would-be Wetness Warrior down to the Practical Puddle Positioner.
For the especially zealous, “green roofs”—covering your roof in a thin layer of built-in, living vegetation—are both one of the oldest and the newest in eco-conscious water management. In use for centuries in rural areas around the globe, the green roof concept is now spreading everywhere from suburbia to city industrial parks. They typically reduce stormwater runoff by 50 to 60 percent, depending on various atmospheric conditions, plant cover, and substrate; they extend the life of your roof; and they help to keep your building cool in the winter and warm in the summer. As an added bonus, you can pick tomatoes from your attic.
Those willing to commit to higher capital costs can also replace traditional paving slabs with porous concrete, which allows stormwater to seep directly into the ground. Porous concrete is one of the Environmental Protection Agency’s Best Management Practices for stormwater runoff and could be used for anything from a parking lot to a sidewalk to a neighborhood bike path. With an average flow rate of 3 to 5 gal/ft2/min (read: a lot), porous concrete usually offsets the need for any other type of stormwater management system (including expensive sewer connections for roads and driveways), but it can still be quite costly compared to traditional concrete—sometimes more than $60 per square meter to install—and it requires monthly cleaning to retain its porous properties.
If you’d rather not graze goats on your roof or power-blast your parking lot every month, but you have a little land to spare and a secret yearning for Zen, a rain garden might be perfect for you. Rain gardens are easy to install: form two-plus feet soil into a two- to six-inch depression and fill it with native plants. Water will flow into the garden and seep through the soil in four to six hours, scrubbed of biocontaminants and heavy metals, to replenish the local aquifer. Rain gardens are cheaper than a typical basin because they require less excavation, piping, and concrete, and they’re so flexible size-wise that you can plop them at intervals in the middle of your parking lot. They’re a lot prettier than traditional detention basins, too, and they provide havens for the local wildlife.
A close cousin of the rain garden is the bioswale, a long and gently sloping channel dug perpendicular to the land and populated with native plants. Like the rain garden, a bioswale uses plants and soil to remove contaminants from the stormwater before it returns to the aquifer or surface water. Unlike a rain garden, a bioswale is designed to channel the water over a large surface area, sometimes to a storm drain or surface water. Bioswales are also used in conjunction with rain gardens by channeling roof runoff or other stormwater to them, but in areas of high clay content or other poor soil percolation, they may be the better choice.
Another what’s-old-is-new-again method for stormwater management is rain harvesting: the capture and containment of stormwater for later use. This can be as simple as a gutter-fed cistern (a technique used for thousands of years) or as complex as an underground containment/pumping system that recycles rainwater for “greywater” uses such as flushing toilets and watering the lawn. This is particularly useful in the drought-prone areas of southeast Oregon, where with the help of your cisterns, you may end up with the only green lawn in town come August.
One of the most simple, economic, and widely-used methods of stormwater retention is the retention basin, which is essentially a manmade pond surrounded by native vegetation. Unlike a detention basin (which holds overflow temporarily until it can be channeled to a drain or surface water) or an infiltration basin (which is designed to capture water and drain it rapidly into the underlying aquifer), retention basins are designed to hold water, often permanently, while adding an element of natural beauty to the landscape. Like other EPA Best Practices Management solutions, retention basins, which are fed via a network of storm drains and pipes both above and under the ground, help to filter toxins from the water and replenish the local aquifer. They’re a great choice for new neighborhood and commercial construction, since they can be installed for as little as $17.50 per cubic meter in the right conditions, and their beauty adds tremendous value to the local real estate.
The rain will fall (and fall, and fall, and fall some days) whether we like it or not. So during your next construction or renovation, why not buck up on your green creds by selecting one of the above eco-friendly stormwater management solutions. The soil will thank you, the water will thank you, and your customers, residents, and roof goats may never suffer rain-soaked toes again.