Tips and Techniques on Creating and Keeping the Perfect Lawn
Controlling Non-Point Source Runoff Pollution from Roads,
Highways, Highways, and Bridges
Roads, highways and bridges are a source of significant contributions of pollutants to our nations waters. Contaminants from vehicles and activities associated with road and highway construction and maintenance are washed from roads and roadsides when it rains or snow melts. A large amount of this pollution is carried directly to water bodies.
Contaminants in Runoff Pollution:
Runoff pollution is that associated with rainwater or melting snow that washes off roads, bridges, parking lots, rooftops and other impermeable surfaces. As it flows, over these surfaces, the water picks up dirt and dust, rubber and metal deposits from tire wear, anti-freeze and engine oil that has dripped onto the pavement, pesticides and fertilizers and discarded cups, plastic bags, cigarette butts, pet waste and other litter. These contaminants are carried into our lakes, rivers, streams, and oceans.
Contaminants in runoff pollution from roads, highways and bridges include:
Sediment: sediment is produced when soil particles are eroded from land and transported to surface waters. Natural erosion usually occurs gradually because the vegetation protects the ground. When land is cleared or disturbed to build a road or bridge, however, the rate of erosion increases.
The vegetation is removed and the soil is left exposed, to be quickly washed away in the next rain. Erosion around bridge structures, road pavements, and drainage ditches can damage and weaken these structures.
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Soil particles settle out of the water in a lake, stream, or bay onto aquatic plants, rocks, and the bottom. This sediment prevents sunlight from reaching aquatic plants, clogs fish gills, chokes other organisms and can smother fish spawning and nursery areas.
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Other pollutants such as heavy metals and pesticides adhere to sediment and are transported with it by wind and water. These pollutants degrade water quality and can harm aquatic life by interfering with photosynthesis, respiration, growth, and reproduction.
Oils and Grease:
Oils and grease are leaked onto road surfaces from car and truck engines, spilled at fueling stations and discarded directly onto pavement or into storm sewers instead of being taken to recycling stations. Rain and snowmelt transport these pollutants directly to surface waters.
Heavy Metals:
Heavy metals come from some “natural” sources such as minerals in rocks, vegetation, sand and salt. They come from car and truck exhaust, worn tires and engine parts, brake linings weathered paint, and rust. Heavy metals are toxic to aquatic life and can potentially contaminate ground cover.
Debris:
Grass and shrub clippings, pet water, food containers and other household wastes and litter can lead to unsightly and polluted water.
Pet waste from urban areas can add enough nutrients to estuaries to cause pre-mature aging or “eutrophication.”
Road Salts:
In the snow belt, road salts can be a major pollutant in both urban and rural areas. Snow runoff containing salt can produce high sodium and chloride concentrations in ponds, lakes, and bays. This can cause unnecessary fish kills and changes to water chemistry.
Fertilizers, Pesticides, and Herbicides:
If these are applied excessively or improperly, fertilizers, pesticides and herbicides can be carried by rainwater from the green parts of public-rights-of-way. In rivers, streams, lakes, and bays fertilizers contribute to algal blooms and excessive plant growth and can lead to eutrophication. Pesticides can be harmful to human and aquatic life.
Erosion gullies on land cleared of vegetation at a road construction site are a sign of sediment runoff. Iridescence, rainbow colors, in runoff water is a sign of pollution of spilled petroleum products.
Other signs of runoff pollution during road construction include obvious changes in streams or rivers downstream from the construction such as bank erosion and sloughing, muddy or oily water, and sandbar relocation. Clumps of mud on roadways leaving a construction site can lead to sediment flows heading for drainage ditches and storm inlets that empty into nearby streams. Best management practices such as permanent storm water retention/detention ponds, slope protection or grass strips and temporary sediment traps, silt fences, diversion trenches, and provisions for washing vehicles before they leave the construction site are all means to reduce runoff.
The Environmental Protection Agency (EPA) has developed several programs with specific guidelines and regulations. To learn more about these programs, contact your local EPA office.
EPA/ Polluted Nonpoint Source Pollution.