Sediment control

A sediment control is a practice or device designed to keep eroded soil on a construction site, so that it does not wash off and cause water pollution to a nearby stream, river, lake, or sea. Sediment controls are usually employed together with erosion controls, 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.[1]

Silt fence EPA
Silt Fence installed on a construction site.

Commonly used sediment controls

Hay bales more outside stack showing stack size near Yass Australia photo taken November 2015 03
hay bales are sometimes used in sediment control

Active treatment systems

Chemical treatment of sediment, commonly called an active treatment system, is a relatively new form of sediment control for the construction industry. It is designed to reduce turbidity in nearby water bodies and involves collection of sediment-laden stormwater in a basin or tank, and adding a chemical flocculant. An example video of chemical dosing on slow settling solids is on YouTube.[3] This causes the sediment to settle so it can be more easily removed from the water. Some of the flocculent chemicals used for sediment treatment are chitosan and polymers such as polyacrylamide. The water is then pumped through a removal system, such as a Siltbuster, sand or cartridge filter, prior to discharge. Chemical sediment control is currently used on some construction sites around the United States and Europe, typically larger sites where there is a high potential for damage to nearby streams.[4]

Another active treatment system design uses electrocoagulation to flocculate suspended particles in the stormwater, followed by a filtration stage.[5]

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 1 acre (0.40 ha) and larger. Smaller sites which are part of a common plan of development (e.g. a residential subdivision) are also required to have ESCs.[6] In some states, non-contiguous sites under 1-acre (4,000 m2) are also required to have ESCs. For example, the State of Maryland requires ESCs on sites of 5,000 sq ft (460 m2) or more.[7] 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.

See also

References

  1. ^ Basic Erosions and Sediment Control. Virginia Department of Conservation and Recreation. 2010.
  2. ^ State of Washington. Department of Ecology. Olympia, WA. “Stormwater Management Manual for Western Washington.” Volume II –Construction Stormwater Pollution Prevention. 2005.
  3. ^ Example video of chemical dosing on slow settling solids
  4. ^ California Stormwater Quality Association. Menlo Park, CA. “California Stormwater BMP Handbook: Chemical Treatment.” Fact Sheet No. SE-11. January 2003.
  5. ^ Benedict, Arthur H., et al. 2004. "Raising the Bar on Construction Stormwater Treatment." Stormwater: May–June 2004.
  6. ^ United States Environmental Protection Agency (EPA). “Regulations for Revision of the Water Pollution Control Program Addressing Storm Water Discharges; Final Rule” (Commonly called the “Phase II Stormwater Rule.”) Federal Register, 64 FR 68721, December 8, 1999.
  7. ^ State of Maryland. Code of Maryland Regulations (COMAR). Activities for Which Approved Erosion and Sediment Control Plans are Required. Sec. 26.17.01.05.

External links

CPESC

Certified Professional in Erosion and Sediment Control (CPESC) is a qualification indicating the holder has educational training, expertise and experience in controlling erosion and sedimentation, and met certification standards.

Cochiti Dam

The Cochiti Dam is an earthen fill dam located on the Rio Grande in Sandoval County, New Mexico, approximately 50 miles (80 km) north of Albuquerque, New Mexico, in the United States. By volume of material, it is the 23rd largest dam in the world at 62,849,000 yd3 (48,052,000 m3) of material, one of the ten largest such dams in the United States, and the eleventh largest such dam in the world. Cochiti Dam is one of the four United States Army Corps of Engineers projects for flood and sediment control on the Rio Grande system, operating in conjunction with Abiquiu Dam, Galisteo Dam and Jemez Canyon Dam.

Erosion control

Erosion control is the practice of preventing or controlling wind or water erosion in agriculture, land development, coastal areas, river banks and construction. Effective erosion controls handle surface runoff and are important techniques in preventing water pollution, soil loss, wildlife habitat loss and human property loss.

Fiber roll

A fiber roll is a temporary erosion control and sediment control device used on construction sites to protect water quality in nearby streams, rivers, lakes and seas from sediment erosion. It is made of straw, coconut fiber or similar material formed into a tubular roll.

Geosynthetics

Geosynthetics are synthetic products used to stabilize terrain. They are generally polymeric products used to solve civil engineering problems. This includes eight main product categories: geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells and geocomposites. The polymeric nature of the products makes them suitable for use in the ground where high levels of durability are required. They can also be used in exposed applications. Geosynthetics are available in a wide range of forms and materials. These products have a wide range of applications and are currently used in many civil, geotechnical, transportation, geoenvironmental, hydraulic, and private development applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, erosion control, sediment control, landfill liners, landfill covers, mining, aquaculture and agriculture.

Geotextile

Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. Typically made from polypropylene or polyester, geotextile fabrics come in three basic forms: woven (resembling mail bag sacking), needle punched (resembling felt), or heat bonded (resembling ironed felt).

Geotextile composites have been introduced and products such as geogrids and meshes have been developed. Geotextiles are able to withstand many things, are durable, and are able to soften a fall if someone falls down. Overall, these materials are referred to as geosynthetics and each configuration—geonets, geosynthetic clay liners, geogrids, geotextile tubes, and others—can yield benefits in geotechnical and environmental engineering design.

Great Lakes Basin Soil Erosion and Sediment Control Program

The Great Lakes Basin Soil Erosion and Sediment Control Program is an American federal and multi-state environmental and agricultural program to water quality, land use, and agricultural productivity pertaining to the Great Lakes Basin. It was authorized by the Farm Security and Rural Investment Act of 2002 (P.L. 107-171, Sec. 2502). Under the program, $5 million is authorized annually in discretionary funds from FY2002 through FY2007 to implement new authority for a soil erosion and sediment control program in this basin that had been established in a number of prior enactments.

Infiltration/Inflow

Infiltration/Inflow (I/I) causes dilution in sanitary sewers. Dilution of sewage decreases the efficiency of treatment, and may cause sewage volumes to exceed design capacity. Although inflow is technically different from infiltration, it may be difficult to determine which is causing dilution problems in inaccessible sewers. The United States Environmental Protection Agency defines the term infiltration/inflow as combined contributions from both.

Lake Bernard Frank

Lake Bernard Frank (Lake Frank), is a 54-acre (220,000 m2) reservoir on the North Branch of Rock Creek in Derwood, Maryland, USA, just east of Rockville. It is named after Bernard Frank, a wilderness activist and a co-founder of The Wilderness Society. The lake's boundaries are, approximately, Route 28, East Gude Drive, Avery Road, and Muncaster Mill Road. Lake Frank was created in 1966 to aid in flood and sediment control, as well as to provide recreation. It has an earthen dam, installed in 1967, on its southern side. It was created as a sister lake to Lake Needwood. Lake Frank is owned by the Maryland-National Capital Park and Planning Commission (M-NCPPC).

The lake's secluded location within Rock Creek Regional Park is another of its assets. Visitors to the lake must bike or walk about 1/4 of a mile from all parking lots to get to the lakeshore. The Lake Frank & Meadowside Trails surround the lake, making it a favorite hiking spot. Also, locals enjoy fishing from the shoreline, though a license is needed to do so. However, swimming, boating, and ice skating are prohibited.

The main trail around Lake Frank, the Lakeside Trail, is a 3​1⁄4 mile long loop. Approximately 2/3 of the trail is unpaved and traverses the woods surrounding the lake. The other part of the trail is wider and paved. At the approximate half-way point of the trail, there is a creek that must be crossed. Though there are a group of rocks which form a bridge-like path across, the creek may be impassable depending on the water level.

Mauvoisin Dam

Mauvoisin Dam is a concrete variable radius arch dam across the Val de Bagnes on the Dranse de Bagnes stream, in the canton of Valais, Switzerland. Initial construction on the dam commenced in 1951 and was completed in 1957, with the reservoir filling by 1958. In 1991, the dam was raised to increase the capacity of the reservoir for winter storage. The dam's primary purpose is hydroelectric power generation.

The eighth highest dam in the world, Mauvoisin stands 250 metres (820 ft) high and 520 metres (1,710 ft) long, with a structural volume of 2,030,000 cubic metres (2,660,000 cu yd). The impounded water behind the dam forms the 4.9-kilometre (3.0 mi) Lac de Mauvoisin, which has a capacity of 211.5 million m3 (171,500 acre feet) and a full surface area of 208 hectares (510 acres). The dam and reservoir control runoff from a catchment of 167 square kilometres (64 sq mi). Flood waters are released by a gated spillway with a capacity of 107 m3/s (3,800 cu ft/s).

Water from the dam is fed to two hydroelectric power stations with a combined capacity of 363 megawatts (MW). Mauvoisin Dam provides a hydraulic head of 482 m (1,581 ft) to the Fionnay generating station, which can produce 138 MW from three Francis turbines. The water then drops another 1,014 m (3,327 ft) to the Riddes generating station, where it drives five Pelton turbines with a combined capacity of 225 MW. The two plants produce about 943 million kilowatt hours (KWh) each year, with Fionnay generating 278 million KWh (29.5%) and Riddes generating 665 million KWh (70.5%).Mauvoisin Dam also serves for flood prevention and sediment control. The dam helps protect the Bagnes and Rhône river valleys from glacial lake outburst floods such as ones that occurred in 1595 and 1818. During the 1960s and 1970s, Giétro Glacier adjacent to Lac de Mauvoisin threatened to produce icefalls, which could have overtopped the dam. Giétro has retreated since 1980, eliminating the threat of such an event. The dam also traps about 300,000 m3 (390,000 cu yd) of sediment each year, helping to extend the life of downstream hydroelectric plants. However, sediment accumulation also poses a threat to the dam's useful life; a project to remove sediment has been proposed but has not been implemented because of safety concerns.In 2016, the dam was the location of the world-record highest successful basketball shot. 28-year-old Australian Derek Herron launched a basketball from the top of the dam, where it fell 180 metres directly into a net placed on the ground below.

Pick–Sloan Missouri Basin Program

The Pick–Sloan Missouri Basin Program, formerly called the Missouri River Basin Project, was initially authorized by the Flood Control Act of 1944, which approved the plan for the conservation, control, and use of water resources in the Missouri River Basin.

The intended beneficial uses of these water resources include flood control, aids to navigation, irrigation, supplemental water supply, power generation, municipal and industrial water supplies, stream-pollution abatement, sediment control, preservation and enhancement of fish and wildlife, and creation of recreation opportunities.

It derives its name from the authors of the program -- Lewis A. Pick, director of the Missouri River office of the United States Army Corps of Engineers, and William Glenn Sloan, director of the Billings, Montana office of the United States Bureau of Reclamation.

Sediment basin

A sediment basin is a temporary pond built on a construction site to capture eroded or disturbed soil that is washed off during rain storms, and protect the water quality of a nearby stream, river, lake, or bay. The sediment-laden soil settles in the pond before the runoff is discharged. Sediment basins are typically used on construction sites of 5 acres (20,000 m2) or more, where there is sufficient room. They are often used in conjunction with erosion controls and other sediment control practices. On smaller construction sites, where a basin is not practical, sediment traps may be used.Essential sediment abundance is prevalent in the construction industry which gives insight to future endeavors.

On some construction projects, the sediment basin is cleaned out after the soil disturbance (earth-moving) phase of the project, and modified to function as a permanent stormwater management system for the completed site, either as a detention basin or a retention basin.

Silt

Silt is granular material of a size between sand and clay, whose mineral origin is quartz and feldspar. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water (also known as a suspended load) and soil in a body of water such as a river. It may also exist as soil deposited at the bottom of a water body, like mudflows from landslides. Silt has a moderate specific area with a typically non-sticky, plastic feel. Silt usually has a floury feel when dry, and a slippery feel when wet. Silt can be visually observed with a hand lens, exhibiting a sparkly appearance. It also can be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles).

Silt fence

A silt fence, sometimes (misleadingly) 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 (loose soil) in stormwater runoff. Silt fences are widely used on construction sites in North America and elsewhere, due to their low cost and simple design. However, their effectiveness in controlling sediment can be limited, due to problems with poor installation, proper placement, and/or inadequate maintenance.

Straw

Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number of different uses, including fuel, livestock bedding and fodder, thatching and basket making.

Straw is usually gathered and stored in a straw bale, which is a bale, or bundle, of straw tightly bound with twine or wire. Straw bales may be square, rectangular, or round, and can be very large, depending on the type of baler used.

Surface runoff

Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the Earth's surface. This might occur because soil is saturated to full capacity, because rain arrives more quickly than soil can absorb it, or because impervious areas (roofs and pavement) send their runoff to surrounding soil that cannot absorb all of it. Surface runoff is a major component of the water cycle. It is the primary agent in soil erosion by water.Runoff that occurs on the ground surface before reaching a channel is also called a nonpoint source. If a nonpoint source contains man-made contaminants, or natural forms of pollution (such as rotting leaves) the runoff is called nonpoint source pollution. A land area which produces runoff that drains to a common point is called a drainage basin. When runoff flows along the ground, it can pick up soil contaminants including petroleum, pesticides, or fertilizers that become discharge or nonpoint source pollution.In addition to causing water erosion and pollution, surface runoff in urban areas is a primary cause of urban flooding which can result in property damage, damp and mold in basements, and street flooding.

Universal Soil Loss Equation

The Universal Soil Loss Equation (USLE) is a widely used mathematical model that describes soil erosion processes.Erosion models play critical roles in soil and water resource conservation and nonpoint source pollution assessments, including: sediment load assessment and inventory, conservation planning and design for sediment control, and for the advancement of scientific understanding. The USLE or one of its derivatives are main models used by United States government agencies to measure water erosion.The USLE was developed in the U.S., based on soil erosion data collected beginning in the 1930s by the U.S. Department of Agriculture

(USDA) Soil Conservation Service (now the USDA Natural Resources Conservation Service). The model has been used for decades for purposes of conservation planning both in the United States where it originated and around the world, and has been used to help implement the United States' multibillion-dollar conservation program. The Revised Universal Soil Loss Equation (RUSLE) and the Modified Universal Soil Loss Equation (MUSLE) continue to be used for similar purposes.

Water pollution

Water pollution is the contamination of water bodies, usually as a result of human activities. Water bodies include for example lakes, rivers, oceans, aquifers and groundwater. Water pollution results when contaminants are introduced into the natural environment. For example, releasing inadequately treated wastewater into natural water bodies can lead to degradation of aquatic ecosystems. In turn, this can lead to public health problems for people living downstream. They may use the same polluted river water for drinking or bathing or irrigation. Water pollution is the leading worldwide cause of death and disease, e.g. due to water-borne diseases.Water pollution can be grouped into surface water pollution. Marine pollution and nutrient pollution are subsets of water pollution. Sources of water pollution are either point sources and non-point sources. Point sources have one identifiable cause of the pollution, such as a storm drain, wastewater treatment plant or stream. Non-point sources are more diffuse, such as agricultural runoff. Pollution is the result of the cumulative effect over time. All plants and organisms living in or being exposed to polluted water bodies can be impacted. The effects can damage individual species and impact the natural biological communities they are part of.

The causes of water pollution include a wide range of chemicals and pathogens as well as physical parameters. Contaminants may include organic and inorganic substances. Elevated temperatures can also lead to polluted water. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. Elevated water temperatures decrease oxygen levels, which can kill fish and alter food chain composition, reduce species biodiversity, and foster invasion by new thermophilic species.Water pollution is measured by analysing water samples. Physical, chemical and biological tests can be done. Control of water pollution requires appropriate infrastructure and management plans. The infrastructure may include wastewater treatment plants. Sewage treatment plants and industrial wastewater treatment plants are usually required to protect water bodies from untreated wastewater. Agricultural wastewater treatment for farms, and erosion control from construction sites can also help prevent water pollution. Nature-based solutions are another approach to prevent water pollution. Effective control of urban runoff includes reducing speed and quantity of flow. In the United States, best management practices for water pollution include approaches to reduce the quantity of water and improve water quality.

Wood wool

Wood wool, known primarily as excelsior in North America, is a product made of wood slivers cut from logs. It is mainly used in packaging, for cooling pads in home evaporative cooling systems known as swamp coolers, for erosion control mats, and as a raw material for the production of other products such as bonded wood wool boards. In the past it was used to fill stuffed toys. It is also sometimes used by taxidermists to construct the armatures of taxidermy mounts.

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