Even slight slopes on a construction site can quickly get out of control if they are not protected from erosion. The force of water flowing across an area of unprotected soil increases significantly when the water is moving from a higher to a lower elevation. This rapid erosion is why it is so important to ensure that a site is stabilized as soon as earthmoving has ceased.
There are several techniques for stabilizing a sloped area on a construction site. One of the most common forms of stabilization is using vegetation to hold the sediment in place. Permanent or temporary seeding may be used in conjunction with mulching to stabilize a large, slightly sloped area. The plants that are seeded will typically grow very fast, using their roots to hold the soil together. Another technique for stabilizing a slope with vegetation is sodding. By laying down sections of already-living sod, a developer can more quickly stabilize an area that sees frequent heavy rains or high winds. There is also hydroseeding, which utilizes a slurry combined of seed and mulch and transported in a tank on a vehicle. This method is designed to quickly disperse the seed by spraying it quickly and evenly along a slope, a much faster process than traditional planting.
For very steep slopes, developers will often use a prefabricated solution in the form of nets, mats, or blankets. These options can be rolled out over an unstabilized area and fastened using staples or stakes. Many modern mats allow for plants to grow through them, or even contain seeds, which leaves an aesthetically pleasing green slope after a few weeks.
Sections of extremely steep slope may not be able to be contained using the techniques discussed above. Sometimes a retaining wall must be constructed using a firmer material, such as concrete or metal, in order to hold sediment in place. A similar dilemma may arise in areas of regular high flow, such as stream and river banks. These slopes can often be stabilized using concrete blocks, or even synthetic grid systems that can hold sediment in place long enough for vegetation to grow along the bank.
In some cases, your slope may need a combination of techniques to stay together. There is no “magic bullet” to prevent erosion, as every site is unique, but no matter how pesky an erosion problem may seem, there are many ways to achieve the desired stabilization.