During construction projects, there are many natural obstacles that site planners need to overcome to avoid delays and maintain regulatory compliance.
From foliage that requires excavation to begin to natural rainwater that can pause activities and cause erosion, it’s natural for planners to become frustrated with Mother Nature.
However, one obstacle that site planners need to pay special attention to is gravity, especially as it relates to erosion and sediment control, and stormwater management. Naturally occurring slopes and hills scattered across worksites can be particularly vulnerable to the harmful effects of wind and rainwater erosion.
Failing to control rainwater on slopes can also lead to concerns about flooding and damage to local infrastructure.
Fortunately, there are several artificial devices and natural controls that planners can use to reduce the impact of erosion on slopes and control the flow of rainwater as it flows away from a work zone.
Before we discuss these controls, it’s important to understand the science behind slope erosion and the benefits that stopping erosion on slopes can have for the rest of your stormwater management efforts.
Why Slopes Are Vulnerable to Erosion
Slope erosion is a naturally occurring phenomenon that can occur on residential sites, urban environments, and active workzones. The three main culprits of slope erosion include rainwater, wind, and human-related activities, such as agriculture and construction.
Unlike flatter areas of your site, gravity tends to concentrate rainwater runoff on slopes, making the soil more susceptible to sheet erosion–erosion caused by large volumes of water that dislodge the soil. Likewise, the bottom of slopes can be subject to rill erosion, which forms when excess moisture cuts little tunnels or gulleys into the soil.
In addition, sloped hills and banks may also be directly impacted by strong winds that can damage the soil and slowly dislodge it over time.
In areas where slopes are located near discharge points or water sources, erosion of these areas can lead to rapid pollution.
For these reasons, it’s essential to take extra precautions when it comes to stopping erosion on sloped hills.
The Importance of Protecting Slopes from Erosion
Soil erosion can strip the topsoil of valuable nutrients and leave the ground more vulnerable to sedimentation. In the latter case, loose sediment particles can become dislodged and mix with rainwater runoff, polluting local streams and water bodies via increased turbidity.
Beyond the standard effects of erosion, slope erosion can also lead to costly effects, such as flooding that can damage nearby infrastructure or even landslides.
From a cost perspective, you will save more money in the long term by preventing erosion, as opposed to going through the costly process of restoring the soil once it’s been eroded.
Most likely, to maintain proper permitting or to discharge stormwater runoff into a public water system, you will need to have proper controls in place to protect against slope erosion.
Best Practices to Stop Erosion on a Slope
Now that we understand the importance of stopping erosion on slopes, it’s time to outline a few best management practices that we and many other environmental consultants use to prevent slope erosion.
1. Vegetative Cover
The easiest and most cost-effective way to protect bare slopes from erosion is to plant vegetative cover. There are several methods to accomplish this, including:
- Hydroseeding: This involves a thick slurry made with grass seeds, tackifiers, fertilizers, and other additives that are sprayed on hills to encourage the quick establishment of grass.
- Mulching: A thick layer of organic materials is spread across hills to protect the soil underneath and encourage the growth of new seeds.
- Cover Crops: Temporary or permanent plants are planted in the ground to help protect the soil, increase infiltration, and slow the rate of stormwater runoff.
The biggest benefit of this approach is it reduces the need to revitalize these areas after projects have ceased, as they will already have a healthy layer of grass or vegetation over the top.
2. Erosion Control Blankets
Similar to vegetative cover are erosion control blankets, which act as temporary cover on bare hills and slopes. Blankets are made of thin, biodegradable material, such as straw, and laid out across slopes to protect the soil underneath from displacement.
Erosion control blankets are quick and easy to install, making them ideal for circumstances that require fast solutions.
3. Silt Fences
Silt fences are a popular form of erosion control used on hills and slopes across construction sites and residential areas. Fences consist of a pliable geotextile fabric attached between wooden posts that helps filter out sediment and pollutants from rainwater. These fences work best when installed along a slope’s contour to trap the most amount of sediment and debris.
Silt fences require a fair degree of maintenance but are effective as temporary controls for small-scale projects.
4. Terracing and Contouring
Another, more invasive way to reduce erosion on slopes is to contour them or create terraced steps that allow water to settle and slow down so that the rest of the slope can get some relief. This method is recommended for high, steep slopes that may be difficult to maintain using other methods.
5. Check Dams
Most sloped hills will naturally develop channels for water and waste to flow through. One control that you can use to filter sediment and allow greater infiltration is known as a check dam. These dams consist of solid materials, such as rocks, sandbags, or logs interspersed across channels to allow sediment to settle and water to settle.
6. Riprap
Sloped surfaces near bodies of water, such as banks, often require extra care to prevent erosion that can spill out sediment into the adjacent water source.
Ripraps are retaining rock walls filled with heavy, angular stones that prevent fine particles from seeping through and help reduce the flow of water down slopes. Ripraps may require a higher upfront cost but require little maintenance and can last for decades.
7. Diversion Channels
Diversion channels redirect water away from vulnerable areas, such as slopes, into areas better equipped to handle the runoff. These channels are often lined with grass or riprap, reducing the impact of runoff and nearby erosion.
Best Practices for Effective Erosion Control
Taking a proactive approach to erosion control on slopes will ensure you have the right plan in place. However, erosion control is not a set-it-and-forget-it deal, but requires active maintenance and checkups, even after construction activity has ceased,
- Site Assessment: Conduct a thorough analysis of the slope’s soil type, gradient, and drainage patterns to determine the areas most vulnerable to erosion.
- Pre-Construction Planning: Develop an erosion control plan before breaking ground, including phasing constriction activities and determining where certain activities will take place.
- Combination of Methods: Use multiple techniques tailored to the site’s specific needs outlined in your SWPPP.
- Regular Maintenance: Inspect and maintain erosion control measures throughout the project. Artificial controls will require the most maintenance.
- Post-Construction Stabilization: Ensure long-term stability by re-establishing vegetation and addressing drainage issues.
Fortunately, you don’t have to approach erosion control alone. The team at Path Light Pro is trained to install, monitor, and report on all erosion control measures on your site, including slopes and hills. For more information, contact our team online!
FAQs
Are erosion control measures expensive?
The cost varies based on the size of the project and chosen techniques. Preventative measures are often more cost-effective than addressing erosion damage later.
How often should erosion control measures be inspected?
We recommend inspecting measures weekly or after heavy rains to ensure they remain functional and effective.
Can erosion control methods harm the environment?
When done correctly, erosion control protects the environment. Use eco-friendly materials and practices to minimize any negative impacts.