If you own land and are planning to do construction on it, you’ll need to stay on top of soil erosion and sediment control.
Erosion is a major source of water pollution, which can be remedied through sediment control.
In this blog, we’ll detail what erosion and sediment control are, and what you need to know as a landowner.
Let’s get started.
1. What is erosion and sediment control?
Erosion is the detachment and movement of soil particles by water, wind, and ice.
Natural erosion normally occurs on a geologic time scale.
However, human activities can alter the landscape and thus the erosion process can be greatly accelerated.
There are four main types of soil erosion: splash, sheet, rill/gully, and stream/channel erosion.
Each of these types of erosion strip the land of the nutrient-rich topsoil, which prompts soil degradation, decreased soil productivity and increased loss of soil structure.
Sedimentation occurs when eroded soil is deposited into water resources or onto land surfaces.
2. What are the three steps involved in soil erosion and sedimentation?
The three main steps of soil erosion and sedimentation are soil particle detachment, transportation, and deposition.
Soil particle detachment is the tearing of soil aggregates or particles of transportable sizes from their moorings in the soil mass.
Detachment can be expressed in terms of pounds or tons per acre.
Often, erosion control practices are designed to help prevent detachment and transportation of soil particles.
Transportation refers to the transportation of materials.
Deposition is when sediments, soils, or rocks are dropped in a different location.
To prevent transportation and deposition, sediment control is designed to trap eroding soil on-site.
As a result, erosion and sediment control work together.
When given an option, erosion control is the better option as it attempts to prevent erosion in the first place instead of after erosion occurs.
3. Why is it important to prevent erosion and sedimentation?
Each year, thousands of acres of land are exposed to erosion and sedimentation during construction and development.
When we don’t have protection and prevention practices in place, the land is left vulnerable to human influences as well as weather (wind, rain, etc.).
Over time, we’ll begin to see soil degradation, which will decrease the soil’s productivity and increase the loss of soil structure.
Furthermore, without sediment control, sediment can erode from exposed areas and accumulate in lakes, natural watercourses, and adjoining properties.
Sediment traveling off-site will runoff into water bodies and accumulate on the bottom of riverbeds, harm aquatic life, increase turbidity, and restrict the amount of sunlight that is available to aquatic plants.
Additionally, sediment decreases storage volume while clogging sewer storm drains.
This increases the potential of flooding and the costs of both power production and drinking water treatment.
To better control erosion and sedimentation, best management practices should be used.
This will help with water pollution control.
4. What are the best management practices for sediment control?
A best management practice (BMP) is defined as a physical, chemical, structural, or managerial practice that prevents, reduces, or treats contamination of water or that prevents or reduces soil erosion.
The following simple and effective measures can help you to retain sediments on your site.
Surface roughening is a temporary practice incorporated during grading that involves scoring the soil surface.
It helps to reduce soil loss by reducing the velocity of runoff.
It can also trap sediment and help to support the establishment of vegetative cover.
Temporary grasses and permanent vegetative cover
By using temporary grasses or permanent vegetative cover, you minimize erosion and sedimentation.
This is because you use the plant roots to stabilize the exposed soils.
Mulch consists of a group of organic and inorganic materials that are spread on the soil surface to prevent the movement of soil by wind and rain.
Mulch helps to minimize erosion by providing protective cover over disturbed, bare, or reseeded soils.
Even a minimal thickness of mulch protects soils from splash erosion, while thicker layers are effective for additional sediment control.
Erosion control blankets are mats comprised of organic fibers or inorganic materials held by synthetic or biodegradable netting.
These blankets help to prevent erosion from exposed soils in channels or slopes.
They are also a great wet weather measure and are usually used when a vegetative cover can’t be achieved due to soils, time of year, or where slopes are too steep for mulch.
This practice helps to minimize wind erosion of bare soils.
5. What regulations do we have to prevent sedimentation from happening?
Did you know that an estimated 80 million tons of sediment are washed from construction sites into U.S. lakes, rivers, and waterways each year?
As more natural land is cleared for residential and commercial use, there is an increased risk of sediment entering and polluting our water.
So, it’s critical that we confront the risk that erosion and sedimentation possess.
Some counties will enforce land disturbance laws and regulations on anyone who is performing construction on a certain amount of land.
For example, the Fairfax County Erosion and Sediment Control Law requires that anyone causing a land disturbance exceeding 2,500 square feet must prepare an erosion and sediment control plan.
What does this plan include?
Often, it includes minimum standards to reduce soil erosion and requires the use of best practices to prevent eroded sediments from leaving the site.
Before you can begin construction activities, you must receive approval from the appropriate county personnel.
Your project will also be subject to inspection, and if violations are found, then laws normally provide for enforcement actions and penalties.
6. What erosion and sediment controls are found on construction sites?
Construction can do a lot of damage to the land in the form of erosion.
Here are some of the common types of erosion and sediment control found on construction sites.
This control is a temporary sediment barrier made of woven synthetic filtration fabric supported by steel or wood posts.
It should be installed below disturbed areas where erosion is expected to occur.
A silt fence helps contain sediment within the construction site.
The bottom four inches of fabric must be buried beneath the soil surface to prevent sediment from going under the fence.
Double silt fence
This control is a double layer of silt fences, often further protected by a chain-link fence.
Super silt fence
This control is a fence that has metal poles spaced 10 feet apart, which supports a chain-link fence.
A woven synthetic filtration fabric is also stretched across its length.
All of these materials help to make it sturdier and less likely to be broken than a regular silt fence.
This control doesn’t have a formal design, but its purpose is to protect desirable trees from mechanical or other injuries.
This control prevents sediment from entering storm drains.
This control is a temporary reservoir built to retain sediment and debris within a controlled stormwater release structure.
It differs from a sediment trap in that it serves a larger drainage area (three or more acres up to 100 acres).
This control is a temporary reservoir built to retain sediment and debris on a drainage area of fewer than three acres.
The trap is formed by building a predetermined reservoir confined by an earthen embankment with a pipe outlet.
If the property is less than an acre, then a stone outlet is sufficient.
This control is necessary for areas with surface and air movement of dust from exposed soil.
Irrigation with a water truck is a common dust control practice.
This control comes in the form of a stone construction entrance lined with filter fabric to reduce the amount of mud being transported off-site.
If the conditions are muddy enough that sediment isn’t being removed from exiting vehicles by the stone, then the tires must be washed at a wash rack.
This control is a channel with a supporting earthen embankment on the lower side constructed across or at the bottom of a slope to intercept surface water runoff.
Normally, the runoff is diverted into a sediment trap or sediment basin.
This control is made of tubing or another conduit of non-erosive material.
It extends from the top to the bottom of a slope with an energy dissipater at the outlet end.
Its goal is to prevent offsite or onsite runoff from eroding a steep slope by containing the runoff as it goes down the slope.
7. How do you prevent erosion on your land?
Erosion is very common on farmland, especially if your property is sloped.
This is because gravity can prompt erosion to escalate quickly.
Fortunately, you can still take steps to protect your soil from erosion.
Here are some ideas to help you enhance sediment control.
Consider your property’s hillside
Certain factors can influence the method that you should use to stop erosion.
Here’s what you should take into account before you move forward.
1. The incline: If your slope is less than 33 percent, then mulch is a great tool to keep your soil secure.
It can also protect the topsoil from degradation.
If you have a greater incline than this, you’ll need to consider how accessible your slope is and how much planting you want to (or are able to) do.
2. Soil make-up: What is the topsoil on your property made of?
Is it mostly rock?
Is it relatively deep?
Get a sense of whether covering vegetation can take root and thrive.
Sandy soils are more likely to runoff than soils with clay makeup because the particles in sandy soils are looser.
Understanding the type of soil you’re working with is one of the top factors that will direct your steps.
3. Drainage: Measure the drainage on the hillside by digging a hole and filling it with water.
Check on your hole after an hour or two.
If there’s no water remaining, then your natural drainage is good.
However, if water is sitting in the hole for two or more days, then this means you have rock rather than soil beneath your hill.
As a result, you may end up with more erosion and will need sediment control measures.
4. Bald spots: Bald spots on your hillside property can inform you about your soil quality.
For example, your lawn may be overly fertilized and poorly irrigated.
Bald spots are also a sign of bedrock right below your soil.
5. Sun or shade: Be mindful of whether this part of your property gets a lot of sun or shade.
When people use cover vegetation to secure the soil, they don’t always consider whether they’re planting something that will thrive in the space.
You want to make sure you choose vegetation that is either prone to thrive in the sun or the shade.
6. Irrigation: Similar to the sun/shade question, does this part of your property receive a lot of water?
Just a little bit?
Whether water is or is not easily accessible to your slope should also designate how you treat the erosion issue.
For example, if you have a hose on the side of your property that can reach the slope, then this could provide an easy solution.
If not, you may be relying on rainwater.
Take action to guard against erosion
When you’re dealing with erosion and attempting to control sedimentation on a hillside, there are a few techniques that are tried and true.
1. Create a garden terrace: This is one of the best soil erosion techniques for a hillside.
You can use homegrown and natural materials to create “terraces” that break up your slopes and act as plateaus.
They help prevent run-off from flowing straight down a hill.
Some plantings (i.e., perennial fruit trees, berry bushes, herbs, etc.) can act as natural terraces.
2. Use plantings to prevent hillside erosion: If you’re looking to stop erosion on a hill on your property, the simplest way to do so is by using plants.
If you select the right type of plants (considering water, sunlight, etc.), then you can protect your land from wind and water erosion and increase water infiltration.
3. Utilize sandbags as diversions: This isn’t an attempt to fight nature as much as to divert it.
Sandbags help when there are heavy rainstorms.
Because there’s likely to be a strong path of runoff and other debris on your hill, you can use sandbags as a consistent and temporary solution to block this path.
Stack them in a stair-stepped formation to make them most effective.
4. Build retaining walls: Retaining walls are a similar approach to erosion as garden terraces.
However, they’re a bit more high-tech as they allow you to create “zones” on your sloped property.
People like to pair this method with strip landscaping and use fountains or lawn furniture to mark off these mini garden areas.
5. Employ geotextiles or erosion control blankets: As mentioned above, erosion control blankets can cover wide areas of soil on a steep hillside.
Some of these blankets are made from synthetic materials known as “geotextiles.”
You can find others that are simply made of organic material like coconut.
They’re biodegradable and protect your soil from erosion.
However, you can still plant over them as they allow seeds to breathe, take root, and shoot up.
Erosion can be a difficult problem on any piece of land.
Thus, it’s necessary to work on erosion prevention and sediment control for the betterment of your property.
Without proper protection, you could inadvertently pollute surrounding waterways and exacerbate degradation on your land.
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Disclaimer: we are not lawyers, accountants or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.