When it rains, it pours - and sometimes it floods or pollutes.
That's the problem with stormwater runoff, a condition that happens when rain falls so fast or heavily that it can't be absorbed by the earth.
Stormwater runoff has become an increasing problem as development creates more hard surfaces like roofs, parking lots and even compacted lawns that interfere with natural drainage, said Sandy Barbic, education specialist with the Summit, Ohio,, Soil and Water Conservation District.
Stormwater poses a number of problems, Barbic said. For one thing, it picks up pollutants such as oil and pesticides as it rushes over the ground, carrying those pollutants to bodies of water - either directly or through storm sewers.
Runoff can also cause erosion, and the dirt that's collected along the way can cause problems in bodies of water by fouling habitats, blocking sunlight and settling on the bottom, raising the base so there's less room for water and more chance of flooding.
Nitrogen and phosphorus in the runoff can promote growth of algae, which use up oxygen when they die and decay, Barbic said. That leaves less oxygen to support aquatic life.
And in areas with combined storm and sanitary sewers, stormwater can overwhelm the sewers and cause overflows and backups into basements.
While governments wrestle with managing runoff on a big scale, homeowners can make their own dents in the problem by capturing or diverting stormwater. Besides benefiting the Earth, mitigation will reduce stormwater management fees for homeowners in some areas.
Here are some of the methods you can use.
A rain barrel is an oldfashioned idea that's getting new respect. The barrel typically ties into a downspout and collects rainwater coming off a roof, so the water can be reused for purposes such as watering plants and washing cars.
Most rain barrels hold about 190 to 280 litres, only a fraction of the water that can fall on a roof in a heavy rain (2.5 centimetres of rain provides 2,300 litres for every 1,000 square feet of roof, rain barrel proponents note.) But rain barrels can be linked together to increase capacity.
The water they capture is free of the chlorine and salts used in treating water, and its pH is neutral. That makes the water better for plants, proponents say.
Rain barrels need to be level so they fill evenly, and they work better if they're elevated on a base so gravity adds some force to the water as it flows out a spigot near the barrel's bottom, said Jeff Taiclet, a Randolph Township, Ohio, resident who leads workshops on rain-barrel construction. A pump can be added to increase the water pressure.
The base must be strong enough to support one or more barrels, which weigh 180 kg to 230 kg when full, Taiclet said. He suggested making the base of cinder blocks, lumber or an edging of pavers filled with pea gravel.
Rain gardens are collections of native plants in slight depressions that are strategically situated to collect runoff. They're designed to hold the water just long enough to let it percolate into the soil, where it's filtered and cleaned naturally.
Native plants are recommended because they require little maintenance and don't normally need fertilizers or pesticides. The plants used in a rain garden must be able to tolerate both temporary wetness and dry periods between rainfalls, and they must have large root systems to help absorb rainwater.
The simplest rain gardens are depressions about 15 centimetres deep. More effective designs involve digging deeper and either replacing the soil, improving it or creating layers of sand or gravel and soil.
Siting is important. A rain garden needs to be situated down-slope from the house and at least three metres from the foundation, so water doesn't leak into the house. Since the object is drainage, you don't want to put a rain garden in a part of the yard that stays wet for a long time after a rainfall, unless you install a French drain or other drainage system to carry off the excess water.
Unlike traditional pavement that sheds rainwater in sheets, permeable pavement lets water flow through and into the ground. It's sometimes used in commercial settings to reduce runoff from large parking lots, but it can also be used to replace residential patios, driveways and walkways.
The term permeable is often used to describe any type of flow-through paving, but it's only one kind, said Rich Sherer, paving products manager for the Belden Brick Co. in Canton, Ohio. Other types are called porous or pervious, terms that describe how the water gets through the surface.
Strictly speaking, permeable products such as Belden's Aqua-Bric pavers are hard pavers designed so water can flow through the joints between them. Porous and pervious surfaces include concrete and asphalt specially made to let water drain through the material itself, more like a sponge.
The products require engineered bases that can hold and filter the runoff and that take into consideration such aspects as the load, type of traffic and soil type, Sherer said.
Consequently, all types of permeable paving are costlier than traditional methods.
The surfaces need to be cleaned regularly to remove leaves, sediment and other debris that can interfere with drainage. Experts also note that porous pavement is prone to failure, especially if it's improperly designed or installed.
Other things you can do to reduce runoff:
- Mow properly to encourage deeper, stronger grass roots that absorb water better. Keep the mower blade sharp, mow to a height of six to nine centimetres and cut the grass often enough that you remove no more than one-third of the leaf blade at a time.
- Leave grass clippings on your lawn. As they break down, they add nutrients to the soil to feed the grass.
- Water wisely. Make sure sprinklers are watering plants, not surfaces such as driveways and sidewalks. If you choose to water your lawn during dry periods, do it infrequently and deeply.
- Wash your car on the lawn instead of the driveway. The soapy water will be absorbed into the soil and cleaned naturally, rather than running into a storm sewer.
- Aerate your lawn periodically. Core aeration pulls plugs of soil out of the lawn, making it easier for oxygen, water and nutrients to reach grass roots and easing compaction.
- Test your soil. A soil test will tell you what your soil needs, so you don't add unneeded fertilizer.