Bulkhead Erosion Control is an important process that prevents soil displacement, rebuilds slopes, assists in landscaping and reduces water runoff. In addition, effective erosion control is often a requirement of state and federal regulations for many projects and applications.
Erosion Control includes techniques such as silt fences, erosion blankets, drainage systems and sediment ponds. It also involves replanting vegetation and constructing permanent barriers.
Soil Stabilization is the chemical or mechanical improvement of a soil’s engineering properties. For example, a base soil that provides the foundation for a house or road needs to be strong enough to support whatever is constructed on it. Soil stabilization increases the shear strength of a soil to prevent it from crumbling under heavy loads.
This can be done by mixing the soil with different materials or adding certain additives that will make it stronger. Typical methods include lime, cement and polymer soil stabilizers.
These chemicals will bond with the soil particles on a molecular level to form a hard surface that is impermeable and resistant to erosion. Lime is a popular soil stabilizer because it makes clay soils less plastic and more durable, making it more suitable for construction projects. It can be applied to the surface of soils, as it is a liquid, or injected into the ground to minimize disturbance.
Chlorides such as magnesium chloride and calcium chloride can also be used to stabilize soils. They work by pulling moisture into the soil to prevent it from becoming dust that flies up when cars pass over it. They are often sprayed on the top of roads or other unpaved surfaces to protect them from erosion and wear.
A more recent method of soil stabilization is called electro-osmosis. This process utilizes specialized equipment to apply electricity to water-logged soils in order to drain excess moisture and improve their load-bearing capacities and stability. The best part about this technique is that it is environmentally friendly since no additional water or chemicals are required.
Whether it is physical or chemical, the goal of soil stabilization is to provide a solid, even and consistent foundation that can support the construction of buildings, airfields, pavement roads, embankments and river management projects. This will eliminate the need for expensive removal and replacement of soil and protect surrounding vegetation, water bodies and structures.
For construction projects that require an extended period of time, it is important to stabilize the site as soon as possible after construction has commenced in order to avoid potential erosion. Typically, the permittee must take steps to stabilize all exposed soil areas including stockpiles within 14 calendar days after construction activity has ceased.
Vegetation Stabilization
Various natural processes contribute to erosion including wind and water carrying particles that scrape and displace soil layers. Human-induced erosion is also common and can result from improper land management practices like deforestation, overgrazing, and excessive tilling that remove protective vegetation cover. The loss of this vegetation can accelerate erosion, increase the velocity of surface water flow, and exacerbate sediment transport.
A combination of earthworks and plant growth is a key element in slope stabilization and the best way to prevent erosion. Techniques include terracing a steep landscape and using rocks to support the terrain and allow for flora to grow. Living staking is another method that involves planting live cuttings of shrub and tree roots in between riprap to create a vegetative matrix that reduces erosion on the slope and offers protection from water flow.
Vegetation isn’t just effective on its own, however, and requires careful planning. For example, when a site uses permanent seeding to establish long-term vegetation on disturbed soils after construction, it’s important that this seeding is done during the correct season and that the appropriate flora is planted. Weather and seasonality are vitally important to consider as well, since they can have a huge impact on the success of some short-term soil stabilization methods, such as covering slopes steeper than 3H:1V with erosion control blankets.
On sites that are more vulnerable to erosion, using vegetation in conjunction with other stabilization techniques is essential. This is especially true for areas near structures, such as homes, businesses and schools, where enough erosion could threaten the safety of those living or visiting. Using sediment traps and other structures that direct, slow or divert runoff and reduce the amount of sediment that moves downstream can also be very helpful in this regard.
It is also necessary to consider cost and maintenance factors when choosing an erosion control strategy. Many control measures involve some sort of ongoing expense, and determining the right balance between the long-term expenses, resource availability, and environmental responsibility is crucial. Considering guidelines provided by the USDA and Erosion Control Basics can help you choose cost-effective, practical solutions that will last.
Sediment Stabilization
In areas where erosion is a concern, sediment control is often part of construction site best management practices. This practice is important because it reduces the amount of sediment that is lost from the work area and prevents the transport of eroded particles down stream. Effective sediment stabilization controls are critical for reducing stormwater runoff, protecting water quality and preserving habitat for fish and other wildlife.
In some cases, the best option for sediment control is to plant grasses or other vegetation that can help to stabilize the soil. Vegetation has the added benefit of being aesthetically pleasing and can be more attractive than a rip-rap approach to erosion control. Another method of sediment control is to use a Geosynthetic Stabilization Mat (GSM). GSM’s are made from polypropylene or high-density polyethylene and are used on sloped surfaces to slow the movement of water and sediment. GSM’s can also be used in wetlands to prevent the migration of nutrients like nitrogen and phosphorus into waterways.
While sediment control is a very broad topic, there are some essential elements that need to be in place for any project or construction site. To reduce the potential for erosion, it’s necessary to minimize the time that bare soil is exposed during construction. This can be done by using a variety of techniques such as seeding, mulching, erosion control blankets or even chemical treatment.
Non-vegetative methods of erosion control can include putting down gravel, crushed rock or class II aggregate on the ground to eliminate the possibility of surface erosion. These types of materials typically need to be replaced or refreshed periodically depending on the amount of rainfall and wind speed.
Regardless of the type of erosion control used, a bare earth monitoring plan should be in place. This plan should identify all activities that could potentially disturb the soil and the areas where this disturbance is likely to occur. Erosion monitoring will allow for proper construction phasing to reduce the amount of time that the exposed soil is susceptible to erosion from rain and wind. This will help to prevent sediment from being transported away from the construction site and into local streams where it can impact water quality and harm habitat for fish and other aquatic life.
Water Stabilization
Erosion occurs when soil particles are dislodged from their original location and moved by water or wind. This is a problem for construction sites as well as agricultural and river or coastal areas, and can lead to landslides, pollution, decreased crop productivity and loss of topsoil. According to Earth Eclipse, over a billion tons of sediment leaves construction and other work zones each year. This sediment can carry harmful pollutants into our waterways along with other contaminants, making site stabilization a crucial component of erosion control.
Ideally, the best method for controlling erosion is through planting vegetation and mulching. Plants have deep roots that help stabilize soil, preventing it from being washed away by rain or blown away by wind. They also provide a natural filter that helps keep sediment out of our streams, rivers and Chesapeake Bay.
If your construction site can’t afford to plant vegetation, a temporary erosion control blanket can be placed over the soil to help reduce sediment loss until plants become established. These blankets can be purchased from most landscape supply stores, and come in a variety of thicknesses and blends. There are both semi-permanent types that degrade over time and permanent models made from a higher percentage of synthetics for longer term applications.
It is important to note that erosion control measures are often required by state and local regulations. If your company is working on a road or bridge project, for example, you may be required to use specific erosion and sediment control products.
Non-vegetative methods can be used to control erosion as well, and include items like silt fences, bio rolls, rock checks and drainage swales. These are typically used in conjunction with vegetation and soil stabilization BMPs, and are not considered to be a standalone solution for erosion control.
It is also important to phase construction when possible, so that a large amount of soil is not exposed at one time. This can be accomplished by flagging or putting up signs to indicate the area that is not to be disturbed, as well as using other BMPs designed for steep slopes such as terracing and slope draining.