Silt Fences

A silt fence sometimes called a "filter fence," is a temporary sediment control device used on construction sites to protect water quality in nearby streams, rivers, lakes, and seas from sediment in stormwater runoff.

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Sediment containment is a critical issue in watershed management in order to provide for erosion control and continue economic viability. Because erosion is mostly controlled by the amount of sediment deposited in streams and rivers, a permanently installed government-approved (and maintained) silt fence has the potential to effectively reduce stream channelization, provide temporary support for downstream erosion control activities, and reduce the amount of water entering puddles. Unlike a dam, the silt fence is built into the slope it is on, absorbs flowing water and prevents channelization, as well as retains the sediments within the partition.

 

A common misconception is that a silt fence stops flowing water. In reality, it keeps the sediment from entering the waterway. Reclamation applications that involve moving or disturbing sediments must proceed with extreme caution to avoid disturbing fragile ecosystems. Installing a silt fence is easily integrated into agencies and homeowners’ maintenance schedules, and can reduce flooding, reduce erosion, improve fish passage, and even provide wildlife refuges. Such projects require the collaboration of local watershed management agencies and public agencies on the local and regional level.

 

Consideration should be given to how to install and maintain the silt fence as a permanent component of the existing infrastructure. If you have any questions about silt fences, we are happy to provide assistance. For more information, drop us an email at dan@eco-constructors.com.

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Silt fences are often installed as perimeter controls.

Lines are crucial in a prevention/mitigation method, to maintain adequate water monitoring thresholds and restore flows to balance watershed flows. VOC monitoring strategies include expanding their sampling (with device and/or stationary air samplers during low flows, or in higher flow times), learning more about the distribution of VOCs from forested watersheds and aquatic systems, and constructing stricter monitoring/retention protocols at proposed and completed construction sites.

 

Commercial research institutions often contract with university researchers to perform VOC monitoring. Microbes associated with Standard Pestle Mold kill several types of plants and animals beneficial to crop and livestock production and are a significant agricultural pollutant and cause of surface water pollution. Molds from hardpan rock can reach as deep as 25 ft. across, and hardpan sediment has been found to contain substances that have impacted aquatic systems.

 

A 2007 study demonstrated the effectiveness of a commercial VOC sampling device in establishing critical regulatory thresholds for aquatic life. Results showed significant increases in VOC monitoring success rates (defined as VOCs passing initiated screening tests with 95% specificity) with a depth of at least 200 ft. (the sampling depth is defined by the level of sampling, not the sampling station). Monitoring success rates improve over time as sample depth increases, indicating that downstream economic and ecological analyses may be more effective if the sampling station is located relatively close to watershed plot boundaries.

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Sediment is captured by silt fences most often through ponding of water and settling, rather than filtration by the fabric

In 2015, teams of researchers analyzed sediment aggregates captured from 6 states along the lower Mississippi River watershed using portable air quality sampling devices, including one with a long battery life (~180 days) and another with a fast charge feature (~7 minutes). They used unsupervised machine learning methods to determine the components of sediment aggregation and then used that knowledge to design and evaluate sediment capture algorithms. Initial discoveries were that Methylmercury and other inorganic compounds were the primary constituents of sediment aggregates. Biomass production has been found to increase sediment load in natural landscapes, while pastureland appears to have little effect. There is good evidence from remote sensing studies that livestock production causes elevated levels of nitrogen and phosphorous from soil biological carbonates to enter streams and degrade aquatic food webs. 

 

Sediment bypass network (SBNET)

This is an economic model to improve water quality and lower pollutant loads by capturing aerosols discharged into surface waters. SBNETs are both conceptually simple and technically difficult to execute at scale. Network flows will vary significantly as the number, duration and rate of flows increase.