Coastal Waccamaw
Stormwater Education Consortium www.cwsec.sc.org
What Can You Do to Improve the Quality of Stormwater and Protect Your Local Waterways?
Minimize Impervious Surfaces!
lutants impair water use by both humans and wildlife. Thus, impervious surfaces also threaten water quality.
THE ISSUES
In undeveloped areas, most rainwater infiltrates the ground during a storm, while the rest flows across the surface of the land or evaporates back into the atmos‐ phere. In highly developed, urbanized areas, very little water can penetrate the ground because of large ex‐ panses of impervious surfaces. An impervious surface is any solid structure that prevents rain water from entering the ground. Examples of impervious surfaces include roads, parking lots, driveways, sidewalks and patios, rooftops, and even highly compacted soils. Thus, in these areas, more water is forced to run off the land, carrying with it serious threats to both water quantity and quality.
WHAT CAN YOU DO?
Creating more pervious surfaces, and minimizing the use of impervious surfaces, at your home or business can help mitigate the impact that urbanization has on the important portions of the water cycle that involve water infiltration into the ground, pollution filtration by soils, recharge of groundwater supplies, and control of flash flooding by slow release of water into streams and rivers via groundwater flow. Below are some sug‐ gestions for counteracting the impacts of impervious surfaces. Reduce impervious surfaces on your property by:
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As impervious surface area increases, less water is able to become groundwater and our streams and rivers become “flashier.” A “flashy” stream is one that ex‐ hibits dramatic differences between flows during storms and flows when it is not raining. Flashy streams have a great potential for producing flash floods. Groundwater is responsible for maintaining base flows in our streams and rivers. When ground‐ water becomes scarce, our streams and river go dry. On the other end of the spectrum, since more water is forced to run off the land, more water enters our drainage network, straining the infrastructure and pro‐ ducing floods. In these ways, impervious surfaces pre‐ sent water quantity issues. Anything that falls on an impervious surface is exposed to the elements and can be washed away in a storm event. This includes oil from your car, misplaced fertil‐ izer from your driveway, animal wastes, excess dirt, pesticides, and household cleaning products. During a storm, any of these substances that are on an impervi‐ ous surface will be dislodged and sent to the nearest storm drain which leads directly to a pond, stream, or river without being treated first. These untreated pol‐
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Using alternative driveway/sidewalk materials (grass pavers, mulch, gravel, swept sand pavers, uncemented brick, or pervious concrete) Simply reducing the surface area of your driveway or sidewalk Greenscaping your rooftop with plantings.
Above: Attractive interlocking pavers, bricks, or stone can be substituted for regular concrete in parking and drive‐ way areas, and allow water and common pollutants col‐ lected on parking areas to be filtered through the soils below. Below: Concrete grids or stonework with spaces between that allow grass to grow through are attractive alterna‐ tives for parking spaces and driveways, as are driveways that leave full strips of grass in the middle.
Minimize Impervious Surfaces… continued.
Another option is to retain stormwater on‐site rather than allowing it to flow over the impervious surfaces on your property. This can be done by installing de‐ vices that collect stormwater and encourage ground‐ water infiltration. On‐site retention can be done by: Building a rain garden, which is a depressed flower bed where runoff from your roof, driveway, or flow from your lawn collects and infiltrates (see “Build a Rain Garden” Fact Sheet) • Installing rain barrels that collect water from your gutters downspouts and store it for use in your yard • Rerouting drainage pipes away from impervious surfaces such as driveways, and away from storm drains, and allowing rooftop runoff to be dispersed through your yard. Finally, take care to avoid activities that release water onto impervious surfaces, such as:
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FOR MORE INFORMATION
Many of the stormwater pollution prevention topics addressed in the CWSEC Fact Sheets have some rela‐ tionship with impervious surfaces, stemming from the fact that stormwater runoff is greater in areas of higher impervious surface, and pollutants are more likely to be collected on impervious surfaces and picked up by stormwater. Therefore, you may want to take a look at the other fact sheets and consider some of the recommendations, particularly if you live in an area where the land cover has a large percentage of impervious surface.
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washing cars in the driveway (pull grass onto car to wash it) (See “Properly Maintain Your Vehicle” Fact Sheet) Aiming irrigation heads improperly where water is sprayed on driveways, sidewalks and roadways Opening fire hydrants for recreation, which washes pollutants accumulated on impervious sur‐ faces into nearby stormdrains.