A sediment control is a practice or device designed to keep eroded

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

on a

construction Construction are processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the a ...

site, so that it does not wash off and cause

water pollution Water pollution (or aquatic pollution) is the contamination of Body of water, water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and ...

to a nearby stream, river, lake, or sea. Sediment controls are usually employed together with

erosion control Erosion control is the practice of preventing or controlling wind or water erosion in agriculture, land development, coast, coastal areas, Bank (geography), river banks and construction. Effective erosion controls handle surface runoff and are ...

s, which are designed to prevent or minimize erosion and thus reduce the need for sediment controls. Sediment controls are generally designed to be temporary measures, however, some can be used for storm water management purposes.

Commonly used sediment controls

Hay bales more outside stack showing stack size near Yass Australia photo taken November 2015 03

* Check dam * Diversion dike (temporary) * Fiber rolls * Gabions *Gel Flocculant * Siltbusters * Sand bag barrier * Sediment basin * Sediment trap * Silt fence * Storm drain inlet protection * Straw bale barrier * Turbidity curtain

Active treatment systems

Treatment of silt impacted water using equipment and chemical addition, commonly called an active treatment system, is a relatively new form of sediment control for the construction industry. These systems are designed to reduce Total Suspended Solids (TSS) from entering nearby water bodies where silt pollution can be of environmental concern. Sediment-laden stormwater is collected and or pumped, and a chemical flocculant is added to aide in clarification. Types of flocculant include; * Natural Polymers: Derived from natural sources, such as starch, chitosan, and guar gum. * Synthetic Polymers: These include polyacrylamide and their derivatives, which can be tailored to specific water treatment needs. They are effective at lower dosages compared to inorganic flocculants. * Inorganic Flocculants: Aluminum Sulfate (Alum),

Ferric Chloride Iron(III) chloride describes the inorganic compounds with the formula (H2O)x. Also called ferric chloride, these compounds are some of the most important and commonplace compounds of iron. They are available both in anhydrous and in hydrated f ...

, Ferric Sulfate, Polyaluminum chloride ''Extreme caution should be observed when using cationic flocculants like chitosan or positively charged polyacrylamide or polyDADMAC which cause hypoxia in fish. The use of anionic,negatively charged, flocculants is best practice on open loop treatment systems to ensure the protection aquatic habitat, fish and

invertebrates Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordate subphylum ...

.'' The water is then either filtered (

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

or cartridge filter,) or settled ( lamella clarifier or weir tank) prior to discharge. Chemical sediment control is currently used on some construction sites around the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and Europe, typically larger sites where there is a high potential for damage to nearby streams. Another active treatment system design uses

electrocoagulation Electrocoagulation (EC) is a technique used for wastewater treatment, wash water treatment, industrially processed water, and medical treatment. Electrocoagulation has become a rapidly growing area of wastewater treatment due to its ability to remo ...

to flocculate suspended particles in the stormwater, followed by a filtration stage. Active treatment systems require technical expertise to operate effectively as multiple types of equipment are utilized.

Passive treatment systems

Chemical treatment of water to remove sediment may also be accomplished passively. Passive treatment systems use the energy of water flowing by gravity through ditches, canals, culverts or other constructed conveyances to effect treatment. Self dosing products, such a
Gel Flocculants
are placed in the flowing water where sediment particles, colloids and flow energy combine to release the required dosage, thereby creating heavy flocs which can then be easily filtered or settled. Natural woven fibers like jute are often used in ditch bottoms to act as filtration media. Silt retention mats can also be placed in situ to capture floccules. Sedimentation ponds are often utilized as a deposition area to clarify the water and concentrate the material. Mining, heavy construction and other industries have used passive systems for more than twenty years. These types of systems are low carbon as no external power source is needed, they require little skill to operate, minimal maintenance and are effective at reducing Total Suspended Solids, some heavy metals and the nutrient

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

. Stormwater treatment can also be achieved passively. Stormwater management facilities (SWMF's) are generally designed Stokes' law to remove particulate matter larger than 40 micron in size, or to detain water to reduce downstream flooding. However, regulation on the effluent from SWMF's is becoming more stringent, as the detrimental impact from nutrients like

Phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

either dissolved from (fertilizers), or bound to sediment particles from construction or agriculture runoff, cause algae and toxic

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

(aka Blue-green algae) blooms in receiving lakes. Cyanotoxin is of particular concern as many drinking water treatment plants can not effectively remove this toxin. In a recent municipal stormwater treatment study, an advanced sedimentation technology was used passively in large diameter stormwater mains upstream of SWMF's to remove an average of 90% of TSS and phosphorus during a near 50 year rain event.

Regulatory requirements

All states in the U.S. have laws requiring installation of erosion and sediment controls (ESCs) on construction sites of a specified size. Federal regulations require ESCs on sites and larger. Smaller sites which are part of a common plan of development (e.g. a residential subdivision) are also required to have ESCs. In some states, non-contiguous sites under are also required to have ESCs. For example, the State of

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

requires ESCs on sites of or more.State of Maryland. ''Code of Maryland Regulations (COMAR).'
''Activities for Which Approved Erosion and Sediment Control Plans are Required.''
Sec. 26.17.01.05. The sediment controls must be installed before the beginning of land disturbance (i.e. land clearing, grubbing and grading) and must be maintained during the entire disturbance phase of construction. Approval for use of any chemical flocculant must be obtained prior to its deployment.

References

External links

Erosion Control
- a trade magazine for the erosion control and construction industries
International Erosion Control Association
- Professional Association, Publications, Training
“Developing Your Stormwater Pollution Prevention Plan: A Guide for Construction Sites.”
- U.S. EPA
Gel Flocculant
- Type of semi aqueous flocculant used in Passive water treatment systems {{Authority control Construction Environmental soil science Earthworks (engineering) Gardening aids Stormwater management