There are numerous benefits for using compost to control erosion or sediment. Although compost is still fairly unknown in certain areas of North America, it has been used by landscapers for more than 25 years. Compost berms, blankets or filter socks are extremely effective while enhancing the soil quality for the future. Compost blankets additionally provide excellent stormwater reduction. University research has proven these innovative techniques are effective. In addition, the USEPA has recommended these techniques. The American State Highway and Transportation Officials have even provided national specifications.
A compost blanket was used for the Albion Slopes EcoBlanket project. The placement of the compost was on a severe slope using an application rate of one to two inches for the depth. This technique is used due to the effectiveness of slowing down the sheet flow of water. In areas where there is less rainfall at a lower intensity, there is the potential for lesser application rates. This is effective where the establishment of vegetation for a less severe slope is required. Once it has been applied, the flow of runoff is slowed by the woody portion of the compost by increasing the roughness. The means it becomes less erosive, induces better infiltration into the soil while decreasing the transport of any pollutants.
The woody portion absorbs the rainfall, preventing the particles in the soil from dislodging. This is how soil erosion begins. The finer fraction underneath absorbs a lot of the moisture. This is necessary for optimum plant growth. The University of Georgia revealed research showing an application of two-inches of compost would absorb as much as two inches of rainfall impacting the slope. Compost has unique properties enabling extensive rooting for vegetation or grass. This protects the soil by locking the blanket directly to the slope. It is important to note the majority of compost blankets are equally as effective with or without vegetation. If vegetation is present, the application rates decrease.
University research has consistently revealed compost blankets outperform conventional blankets or hydroseeding. They effectively decrease the volume of runoff storm water during the peak flows in addition to the nutrient loads. The USDA has also proven compost consisting of yard trimmings was capable of much more than just erosion and sediment control. This type of compost can degrade, bind and filter the contaminants when they pass through this layer. The benefits of a compost layer also include the ability to absorb rainfall energy by acting as a buffer or reduce the damage caused by the water and wind.
The structure of the soil is enhanced due to the stimulation of microbial activity causing an increase in the soil’s organic materials. This prevents the facilitation of percolation due to the crusting or compaction of the soil. The water over the surface of the soil is slowed to retain or capture moisture. This facilitates the growth of the plants by reducing the amount of water in the soil. The winter protection is increased by the seed germination or suitable microclimate created to capture the blowing snow. This results in an improvement in the texture of the soil.
Filter socks or compost berms are a type of 3D filter with excellent biofiltration capabilities. When the berms are used for conditions relating to the sheet flow, the filter socks can be used for situations involving water flow issues. A filter sock is when coarse compost is placed inside a thick pantyhose. The reason is s filter sock is easy to stake, then place because the mesh netting material contains the compost media. Either filter socks or compost beams can be use as devices for perimeter control.
Construction site borders or the bottom or top of a slope often have compost beams or filter socks installed around the borders. There is more versatility for filter sock technology, making them effective for the building of living walls or around storm water inlets. One of the key research discoveries for filter socks or compost filter berms is the effectiveness in capturing fine particles. The more conventional devices such as a silt fence do not have this capability. This is extremely important because the fine sediment particles can cause a lot more damage. This is because they can transport a lot farther while remaining in suspension for a longer period of time. They also contain more chemical contamination including petroleum hydrocarbons, nutrients or heavy metals than the larger particles.
The use of compost for a wide variety of different projects has seen significant expansion since the NPDES or the National Pollutant Discharge Elimination System was officially adopted. Phase II was created to regulate construction activities. This regulation requires much better planning from the construction sites. These plans must be placed into effect every single day in accordance with the BMP’s or best management practices to help ensure the plan used will be effective.
