Soil erosion is the process of detachment and transportation of soil materials by water, wind, and gravity.
While geological or natural erosion can produce nearly thirty (30) percent of the total sediment in the United States, accelerated or "man-made" soil erosion accounts for the other seventy (70) percent of sedimentation found in the U.S. Activities ranging from surface mining, forestry, agriculture and construction are all actions which influence accelerated erosion. Although construction by volume does not cause most sediment pollution, it is the most evident and damaging because of the rate at which it occurs. Erosion associated with construction activities can be up to 200 times greater than that from agricultural farmlands and nearly 2,000 times greater than that naturally occurring in grassy and wooded areas and forests.
Erosion problems associated with construction activities can scale from water pollution, flooding, stream channel damage, decreased groundwater storage, slope failures, damage to downstream lands and properties, and of course, the time and costs associated with addressing these issues. Successful minimization of these impacts can be achieved by implementing erosion and sediment control (ESC) measures on construction sites. These Best Management Practices (BMPs) prevent soil movement and soil loss, enhance project aesthetics, reduce complaints and fine, and eliminate appreciable damage to off-site receiving channels, properties, natural resources and surface water bodies.
Erosion control is defined as any source control practice that protects the soil surface and prevents soil particles from being detached by rainfall, flowing water, or wind. Erosion control is also referred to as, “soil stabilization,” and consists of preparing the soil surface and implementing one (1) or more erosion control device Best Management Practice (BMP). All inactive soil-disturbed areas on the project site, and most active areas prior to the onset of rain, must be protected from erosion (soil-disturbed areas may include relatively flat areas and slopes). Typically, steep slopes and large exposed areas require the most robust erosion controls. In turn, flatter slopes and smaller areas still require protection, but less costly materials may be appropriate for these areas, allowing savings to be directed to the more robust BMPs for steep slopes and large exposed areas. To be effective, erosion control BMPs must be implemented on the slopes and disturbed areas to protect them from concentrated flows. It's important to remember that controlling erosion is the first line of defense in preventing sedimentation and stormwater.
Sediment is one of the leading sources of water pollution in the United States.
"Sediment" consists of mineral or organic solid matter that is washed or blown from land into water sources. Sediment pollution is difficult to identify because it comes from non-point sources, such as construction, agricultural and livestock operations, logging, flooding, and city runoff. Each year, water sources in the United States are polluted by over one billion tons of sediment. Sediment can cause large problems, as it can clog municipal water systems, cover and choke aquatic life, and cause an increase in water turbidity.
Though the mud and dirt that make up sediment are natural, they are still serious pollutants that must be prevented from entering the Nation’s water bodies. Some of the other effects of sediment pollution in waterways include:
- Sediment-laden water can prevent natural vegetation from growing in below the water surface.
- Sediment in stream beds disrupts the natural food chain by destroying the habitat where the smallest stream organisms live and causing massive declines in fish populations.
- Sediment increases the cost of treating drinking water which can result in odor and taste problems.
- Sediment can clog fish gills which reduces resistance to disease and lowers growth reproduction rates
- Nutrients transported by sediment can activate algae that release toxins and can make polluting beaches and swimming establishments and potentially causing harm to swimmers.
Sediment control is the implementation, practice or device designed to keep eroded soil on a construction site, so that it does not wash off and cause water pollution to a nearby stream, river, lake, or ocean. Sediment controls are usually employed together with erosion controls, which are designed to prevent or minimize erosion and thus reduce the need for sediment controls. Those sediment control devices or BMPs trap soil particles after they have been eroded by rain, flowing water or wind. They include those particles that intercept and slow or detain the flow of stormwater to allow sediment to settle and be trapped.