The impact of construction is felt beyond the visible assembly of buildings in our community. From land disturbance to changing traffic patterns, construction managers must consider these factors when planning projects to avoid environmental damage and liability issues.
One of the most essential and unavoidable byproducts of construction is the erosion of local soils, which can cause a host of environmental problems for the local ecosystem.
While the EPA and Clean Water Act require strict reporting and permitting for those engaging in land disturbance and construction projects, it’s up to companies to follow through on these promises to limit their impact on the local environment.
This guide will discuss the common causes of soil erosion caused by various human activities, including construction and land clearing. It will also discuss different controls commonly employed to limit the impact of these activities and restore the local soil to its original state.
5 Causes of Soil Erosion in Construction
Manmade soil erosion is a common byproduct of excavation, grading, and material movement. These activities can inevitably lead to erosion in the following forms:
1. Water Erosion
Water is a major agent of soil erosion in construction and is largely unavoidable without the proper controls. For example, as land disturbance and construction activities change the natural shape and slope of landscapes, this can increase stormwater runoff and cause erosion. Likewise, stripping the surrounding landscape of existing vegetation can expose the ground to runoff, eventually leading to sedimentation–a more dangerous byproduct of erosion.
Water erosion can occur in several forms, including:
- Sheet Erosion: The removal of a thin layer of soil across large areas due to rainwater runoff.
- Rill Erosion: The formation of small channels as water runs off disturbed soil surfaces.
- Gully Erosion: The development of deep channels from concentrated water flow, often exacerbated by poor site drainage.
If left uncontrolled, water erosion can lead to sedimentation, flooding, and pollution of local water systems.
2. Wind Erosion
Another natural form of erosion is caused by high or excessive winds that dislodge exposed soils in the ground. Large slopes or hills stripped of natural vegetation are most susceptible to wind erosion. Strong winds can carry soil particles over long distances without proper control, leading to air pollution and sedimentation in nearby water bodies.
3. Land Clearing and Grading
Land clearing is often the first step of any construction project and can significantly contribute to land erosion. Land clearing activities remove the top soil or protective vegetation, exposing soils underneath to erosion and sedimentation.
4. Improper Drainage
Construction sites with inadequate drainage can experience severe erosion due to uncontrolled water flow that can pool or channel in one place.
Poorly designed stormwater management systems increase runoff velocity, leading to soil displacement and sediment transport.
As a rule of thumb, drainage systems and traps should also be checked during inspections to ensure they are discharging properly without backing up.
5. Heavy Machinery and Traffic
Finally, an overlooked but common source of soil erosion often comes from construction equipment and tires. As heavy construction vehicles travel over soft surfaces, they can compact the soil underneath and interfere with its ability to absorb water. This leads to increased surface runoff and erosion, particularly on slopes and near water bodies.
How to Control Soil Erosion in Construction
Most construction-related activities require the development of a stormwater management plan (SWPPP) from local, state, or federal agencies. This plan contains a list of prescriptive controls, known as best management practices (BMPs), designed to control and curtail soil erosion and sedimentation at a worksite.
These BMPs can take several forms, from increasing ground infiltration of stormwater runoff to phasing construction activity to limit disturbance.
- Phasing Construction Activities: By phasing construction activities and limiting land disturbance to one area, you can simplify your erosion control efforts by limiting your impact and making soil restoration easier throughout the course of a project.
- Silt Fencing and Sediment Barriers: Silt fences are among the most common BMPs on construction sites. They help slow the velocity of stormwater runoff while preventing heavy particles from escaping. These fences are made of geotextile fabric stretched between wooden posts.
- Mulching and Vegetative Cover: Applying mulch or planting temporary vegetation stabilizes exposed soil, reduces runoff, and minimizes the impact of rainfall. It also helps speed up the process of restoring vegetation after activities have ceased.
- Erosion Control Blankets and Mats: Using biodegradable erosion control blankets or mats on disturbed areas prevents soil loss and promotes vegetation growth, making them effective on slopes and newly graded surfaces.
- Terracing and Slope Stabilization: On construction sites with steep slopes, terraces, retaining walls, and geotextiles help slow down water movement and reduce soil displacement. This can also help protect against wind erosion.
- Proper Drainage Systems: Installing stormwater management and holding systems, such as retention ponds, swales, and culverts, reduces erosion by directing runoff away from vulnerable areas.
- Controlled Water Flow and Check Dams: Constructing check dams and diversion ditches helps slow water flow, minimizing erosion and sediment transport.
- Dust Control Measures: Construction sites can use water sprays, windbreaks, and soil stabilizers to keep dust and loose soil in place and prevent wind erosion.
- Proper Material Storage and Management: Covering soil stockpiles and storing materials away from drainage areas prevents erosion and sediment transport during storms.
- Water Bank Protection: Installing wattles and ripraps near riverbanks and other water sources can help prevent slope erosion and polluted stormwater from escaping worksites.
The Importance of a Stormwater Management Plan
Controlling soil erosion requires a proactive approach to minimize land disturbance as much as possible, protect bare soils, and revitalize natural vegetation once activity has ceased. Drafting a SWPPP is necessary not only from a regulatory perspective but also from a cost perspective. The more erosion your activity causes, the more you will need to invest in proper control measures.
We recommend partnering with a qualified environmental consultant to help draft a proper SWPPP and monitor ongoing erosion control measures. A consultant trained in SWPPP management can help with everything from permitting to ongoing inspections, saving money and reducing liability.
FAQs
How does vegetation help prevent erosion on construction sites?
Vegetation stabilizes the soil with its root systems, which can help increase ground infiltration, slow runoff velocity, and protect bare soil from erosion.
What are the best practices for erosion control on slopes?
Best practices of slope erosion control include terracing, installing retaining walls, using geotextiles, planting ground cover vegetation, and implementing check dams to slow water flow.
How can construction companies manage wind erosion?
Construction companies can minimize wind erosion by applying water sprays, erecting windbreaks, using dust suppressants, and covering exposed soil with erosion control blankets.