Soil Erosion & Sedimentation Control Training - Unit 4
Study exam for the Soil Erosion and Sedimentation Control Training - Unit 4
Questions and Answers
- 1.
Sediment control should not be used as a _____________________ for erosion control.
- A.
Restriction
- B.
Method
- C.
Substitute
- D.
Motivation
Correct Answer
C. SubstituteExplanation
Sediment control should not be used as a substitute for erosion control because they serve different purposes. Sediment control aims to prevent the movement of sediment particles, while erosion control focuses on preventing the erosion of soil and the loss of topsoil. Sediment control methods, such as silt fences or sediment basins, are effective in trapping sediment but do not address the underlying issue of erosion. To effectively control erosion, measures like slope stabilization, vegetation planting, or retaining walls should be implemented. Therefore, sediment control should not be relied upon as a substitute for erosion control.Rate this question:
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- 2.
Sediment control can be either _______________ or ______________.
- A.
Silt fencing, straw bales
- B.
Vegetative, structural
- C.
Elevation contours, trenching
- D.
Grading, nonwoven geotextile fabric
Correct Answer
B. Vegetative, structuralExplanation
Sediment control can be achieved through two methods: vegetative and structural measures. Vegetative measures involve the use of plants and vegetation to prevent soil erosion and sediment runoff. This can include techniques such as planting grasses or trees, creating buffer zones, or establishing erosion control blankets. On the other hand, structural measures involve the use of physical barriers or structures to control sediment. This can include techniques such as silt fencing, straw bales, or the use of nonwoven geotextile fabric. Both methods are effective in controlling sediment and preventing environmental damage.Rate this question:
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- 3.
Although the required width of a filter strip will vary depending on the slope ___________ and ____________, it should be a minimum width of ________________ feet.
- A.
Length, steepness, 20-25
- B.
Roughness, length, 50-55
- C.
Smoothness, steepness, 10-15
Correct Answer
A. Length, steepness, 20-25Explanation
The correct answer is "length, steepness, 20-25". The width of a filter strip is determined by the length and steepness of the slope. The longer and steeper the slope, the wider the filter strip needs to be. The recommended minimum width for a filter strip is 20-25 feet.Rate this question:
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- 4.
Dense _______________ provides the best filtration.
- A.
Stone
- B.
Grass
- C.
Brush
- D.
Soil
Correct Answer
B. GrassExplanation
Grass provides the best filtration because its dense structure allows it to effectively trap and filter out particles and impurities from water or air. The tightly packed roots and blades of grass create a barrier that helps to retain and absorb pollutants, preventing them from passing through. This makes grass an ideal natural filter for improving water quality and reducing pollution.Rate this question:
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- 5.
Structural practices must be used when __________________ practices are not sufficient to control sediment.
- A.
Vegetative
- B.
Structural
- C.
Erosion
Correct Answer
A. VegetativeExplanation
Vegetative practices refer to the use of plants, such as grasses and trees, to control sediment and erosion. These practices involve establishing vegetation cover, which helps in stabilizing the soil, reducing runoff, and preventing erosion. However, there may be situations where vegetative practices alone are not enough to effectively control sediment. In such cases, structural practices need to be implemented. Structural practices involve the use of physical structures, such as terraces, retaining walls, or sediment basins, to further control erosion and sedimentation.Rate this question:
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- 6.
________________ and ________________ are commonly used along the perimeter of small graded areas to prevent off-site sedimentation.
- A.
Trenches, stone mats
- B.
Crushed stone, geotextile fabric
- C.
Silt fences, straw bales
Correct Answer
C. Silt fences, straw balesExplanation
Silt fences and straw bales are commonly used along the perimeter of small graded areas to prevent off-site sedimentation. Silt fences are temporary barriers made of geotextile fabric that filter out sediment from runoff water, while allowing water to pass through. Straw bales, on the other hand, act as sediment traps by slowing down the flow of water and capturing sediment. Together, these measures help to reduce erosion and prevent sediment from being carried off-site, protecting nearby water bodies from pollution.Rate this question:
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- 7.
____________________ are superior to straw bales for perimeter controls.
- A.
Silt fences
- B.
Trenches
- C.
Elevation contours
- D.
Crushed stones
Correct Answer
A. Silt fencesExplanation
Silt fences are superior to straw bales for perimeter controls because they are specifically designed to prevent sediment runoff and control erosion. Silt fences are made of geotextile fabric that allows water to pass through while trapping sediment, effectively filtering out any contaminants. They are more durable and long-lasting compared to straw bales, which can break down over time and become less effective. Silt fences are also easier to install and maintain, making them a more practical and efficient solution for perimeter controls.Rate this question:
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- 8.
Silt fences should always be trenched in a minimum of __________ inches and installed along the same __________________ across the slope.
- A.
12, steepness
- B.
6, elevation contour
- C.
9, height
- D.
3, elevation
Correct Answer
B. 6, elevation contourExplanation
Silt fences should always be trenched in a minimum of 6 inches and installed along the same elevation contour across the slope. This means that the trench for the silt fence should be dug at least 6 inches deep and should follow the contour of the land, ensuring that the fence is installed level along the same elevation line. This helps to effectively trap sediment and prevent erosion by directing water flow and capturing sediment along the contour of the slope.Rate this question:
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- 9.
Major disadvantages with using straw bales are:
- A.
Very little water will pass through them
- B.
Animals eat them
- C.
Deteriorate rapidly
- D.
Very time consuming to trench them in
- E.
Not cost effective
Correct Answer(s)
A. Very little water will pass through them
C. Deteriorate rapidly
D. Very time consuming to trench them inExplanation
Straw bales have major disadvantages such as limited water permeability, rapid deterioration, and the time-consuming process of trenching them in. Due to their compact nature, very little water is able to pass through the bales, which can hinder irrigation and cause waterlogging. Additionally, straw bales are prone to deteriorating quickly, especially when exposed to moisture, pests, and other environmental factors. Trenching them in requires significant effort and time, making the installation process labor-intensive. Overall, these drawbacks make the use of straw bales less efficient and cost-effective compared to other alternatives.Rate this question:
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- 10.
Tracking can be minimized by restricting vehicular traffic to designated areas. All vehicles should pass over a bed of ___________________ at least _______ feet in length.
- A.
Crushed rock or stone, 50
- B.
Crushed glass, 40
- C.
Stone matting, 30
Correct Answer
A. Crushed rock or stone, 50Explanation
By using crushed rock or stone with a length of at least 50 feet, the tracking of vehicles can be minimized. This is because the rough surface of the crushed rock or stone provides better traction and grip for the vehicles, preventing them from spreading dirt and debris onto other areas. The length of 50 feet ensures that vehicles have enough distance to drive over the crushed rock or stone, effectively removing any dirt or debris from their tires before entering other areas.Rate this question:
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- 11.
______________________ should be placed on the ground prior to placing the crushed rock or stone when attempting to minimize tracking from vehicular traffic.
- A.
Straw
- B.
Nonwoven geotextile fabric
- C.
Sod
- D.
Silt fencing
Correct Answer
B. Nonwoven geotextile fabricExplanation
Nonwoven geotextile fabric should be placed on the ground prior to placing crushed rock or stone to minimize tracking from vehicular traffic. This fabric acts as a barrier, preventing the soil and small particles from mixing with the crushed rock or stone. It allows water to drain through but keeps the soil and particles from getting mixed in, reducing the chances of tracking and creating a more stable and durable surface. Straw, sod, and silt fencing are not suitable options for this purpose.Rate this question:
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- 12.
To effectively control sediment, basins should be at least ______ times as long as wide.
- A.
2
- B.
4
- C.
3
- D.
6
Correct Answer
B. 4Explanation
Basins should be at least 4 times as long as wide to effectively control sediment. This is because a longer basin allows more time for sediment particles to settle out before the water reaches the end of the basin. A wider basin would not provide enough time for sediment to settle, leading to ineffective sediment control. Therefore, a basin that is 4 times longer than its width is the most effective in controlling sediment.Rate this question:
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- 13.
The amount of sediment removed in basins is dependent upon:
- A.
Type of soil in the drainage area
- B.
Time the water remains in the basin
- C.
Velocity of the water flow
- D.
Size and density of sediment particles
- E.
Placing a gravel filter in front of or around the drain inlet
Correct Answer(s)
B. Time the water remains in the basin
C. Velocity of the water flow
D. Size and density of sediment particlesExplanation
The amount of sediment removed in basins is dependent upon the time the water remains in the basin, the velocity of the water flow, and the size and density of sediment particles. The longer the water remains in the basin, the more sediment it can carry and remove. Higher velocity of water flow increases the erosive power, allowing it to carry more sediment. The size and density of sediment particles also play a role as larger and denser particles are more difficult to transport and are more likely to settle. The type of soil in the drainage area and the use of a gravel filter are not mentioned as factors affecting sediment removal in basins.Rate this question:
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- 14.
When designing basin volumes, the engineer must take into account:
- A.
Anticipated storm event
- B.
Velocity of the water flow
- C.
Size of the drainage area
- D.
Time that the water remains in the basin
- E.
Type of soil in the drainage area
Correct Answer(s)
A. Anticipated storm event
C. Size of the drainage area
E. Type of soil in the drainage areaExplanation
When designing basin volumes, the engineer must take into account the anticipated storm event, size of the drainage area, and type of soil in the drainage area. The anticipated storm event is important because it determines the amount of rainfall and runoff that the basin needs to handle. The size of the drainage area is important because it affects the volume of water that will flow into the basin. The type of soil in the drainage area is important because it affects the infiltration rate and drainage capacity of the basin. Considering these factors ensures that the basin is properly designed to handle the water flow and prevent flooding.Rate this question:
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- 15.
The most common way to discharge water from a basin is through a _______________ pipe connected to a horizontal discharge tube.
- A.
Vertical riser
- B.
Perforated
- C.
Dissipating
- D.
Outlet
Correct Answer
A. Vertical riserExplanation
A vertical riser is the correct answer because it is a pipe that is connected to a horizontal discharge tube and is commonly used to discharge water from a basin. A vertical riser allows the water to flow upwards and out of the basin, effectively draining it. This is the most common method of water discharge in basins.Rate this question:
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- 16.
Often the riser pipe is ________________ to allow the water to drain below the top of the pipe.
- A.
Filtered
- B.
Perforated
- C.
Lined
- D.
Protected
Correct Answer
B. PerforatedExplanation
The riser pipe is often perforated to allow the water to drain below the top of the pipe. This means that small holes or openings are made in the pipe to allow water to flow through and drain out. This is important to prevent the water from accumulating and causing damage or flooding.Rate this question:
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- 17.
Energy ________________ are often required at the basin outlet to prevent scouring.
- A.
Dissipaters
- B.
Minimumizer
- C.
Filter
- D.
Damper
Correct Answer
A. DissipatersExplanation
Dissipaters are often required at the basin outlet to prevent scouring. These devices are designed to dissipate or reduce the energy of the flowing water, thereby preventing erosion and scouring of the soil or bedrock. By slowing down the velocity and redirecting the flow, dissipaters help to protect the basin outlet and maintain its stability.Rate this question:
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- 18.
All storm drain _____________ must be protected during construction.
- A.
Risers
- B.
Grates
- C.
Inlets
- D.
Pipes
Correct Answer
C. InletsExplanation
During construction, it is important to protect all storm drain inlets. Inlets refer to the openings or entrances of the storm drain system where water enters. By protecting the inlets, it ensures that debris, sediment, or any other materials do not enter the storm drain system and cause blockages or contamination. This helps to maintain the effectiveness and functionality of the storm drain system, preventing any potential damage or flooding.Rate this question:
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- 19.
Drain inlets can be protected by:
- A.
Covering with straw bales
- B.
Placing a gravel filter in front of or around the drain inlet
- C.
Sealing with an impervious material
- D.
Installing silt fence around the perimeter of the drain inlet
- E.
Wrapping the grate with geotextile materials
Correct Answer(s)
B. Placing a gravel filter in front of or around the drain inlet
C. Sealing with an impervious material
D. Installing silt fence around the perimeter of the drain inlet
E. Wrapping the grate with geotextile materials -
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Mar 22, 2023Quiz Edited by
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Jun 29, 2009Quiz Created by
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