Slope Stabilization and Erosion Control Materials

If you’re a landscape contractor, a property manager that constantly has to battle slopes or areas that are prone to washout, or you’re just someone who loves learning about DIY and everything that comes with it, then you will know that slope stabilization and erosion control are essential. Getting a handle on these things can be tough, and getting a permanent grip on them can be even tougher, but it can be done in most cases.

You simply need to know what materials you should be using based on the terrain you’re dealing with, the slope, and another of other factors that will impact your choice. Luckily for you, we’ve got some options for you, and we’re going to be discussing them down below to give you a better understanding of why these are the best choices, with examples to prove it.

What Does Stone, Gravel, And Aggregate Do?

Stone, gravel, and other aggregates can be used for a variety of purposes, one of which is to help stabilize slopes, and support landscapes that are on an incline. It does this by offering support, increasing internal friction and then interlinking with the soil particles to create something far stronger than the soil is on its own.

They are also a brilliant method of erosion control, as the chosen material essentially acts as a barrier between the water and the soil/other materials, which then prevents them from being washed away. As such, less erosion occurs, which is why choosing the correct material is essential. It has to be something that can withstand and repel the water so that it can continue to protect the soil, which stone, gravel, and other aggregates all can do.

But, how do you choose the right one? How do you know which is the best to use in any given situation? How can you find the best erosion control gravel and where does it work best? How do certain types of stone and rock hold up against gravity? These are good questions, and that’s what the rest of this article is going to focus on.

Considering Soil Type

Before we look into the different materials that we’re going to suggest, it’s important to understand that the soil type is going to play a key role in what material you should choose. The reason for this is that different types of soil behave differently when under pressure, and placing these stones on top of it is going to do exactly that. As well as this, moisture and movement also cause different reactions in different types of soil,

As a brief overview before we get into it, looser soils where the particles tend to shift more easily, larger rocks tend to be the better option. This is because they are needed to provide an interlocking stability to the soil itself, helping prevent erosion, and general movement of the soil. Then, in areas where there is soil that tends to hold more water, you need a type of aggregate or stone that avoids the soil from becoming overly saturated, and leading to it becoming unstable.

There are some types of soil that are easy targets for erosion, and these may benefit from a combination of types of stone to assist with drainage, keep them in place, and also protect the surface. Whereas smaller stones are more often used when the ground already has good drainage and natural stability as they cannot provide this mass that other stones can.

It can be tough to know when to use what type of stone or aggregate, which is why we’re going to have a more detailed look now into examples of when we think it’s best to use each type of stone, and why.

Suggested Material Options

Riprap & Large Rock (3”-12”)

The first option that we’re going to consider is Riprap for erosion control, and large rock. If you’ve never heard of riprap, it’s a large, handplaced rock that has the specific purpose or erosion control and is often used for shorelines, and riverbanks specifically. It is known as rock armor, because it takes on the role of protection of the soil or the shore, by dispersing the energy of the fast-flowing river or sea. This helps to calm the water back to where it should be, avoiding it getting anywhere near the riverbank or the shore. As such, this rock for riverbank erosion purposes is an excellent option.

Riprap and hard rocks are used for the heaviest kinds of stabilization, so while we’ve given the examples of riverbanks and shorelines, it can be used for any large area that needs a lot of help with erosion control. On top of that, riprap and large rocks are also useful for steep slopes and hillside stabilization. To prepare this and provide the necessary support, clear the area, shape the slope, and then lay down a fabric layer before placing the riprap or large rocks. The fabric layer is essential for support here, so it’s not a step you should be skipping.

They are extremely durable, so not only can they withstand the lashings from the water, either a large body or the rain, but also any heavy foot traffic that may come this way. These rocks will stand the test of time as long as they are laid properly.

Gravity can move them over time if the slope is too steep, or if other forces have reduced its stability, but you will be able to see this and can take steps to fix it. Generally though, riprap and large rocks are there to stay, we would recommend just checking on them every now and then, especially if there has been heavy forces exerted, or there seems to have been a change in the landscape.

Boulders and Large Accent Stones

If you’re working with high risk slopes, you’ve already got your work cut out for you, so the last thing that you need is your stones working against you. Boulders and large stones play a critical role in structural anchoring on high-risk slopes, and other areas such as embankments. By placing these heavy stones strategically, you will be able to reinforce soil stability, and slow erosion at the same time. As well as this, it will help to distribute the gravitational forces more evenly, reducing the risk of a gravity slip as the pressure will be dispersed across the unstable ground.

This form of slope stabilizing rock will act as a retaining element, reducing the risk of slope failure, which is the last thing that you want. So, use these larger materials as a structural anchor, ensuring that they are distributed correctly to avoid any further issues with your slope. Once you’ve completed this, it should be as stable as possible as they reinforce the overall integrity of the vulnerable steep slope.

You may be worried about how this is going to make the area look, but you don’t need to worry because the majority of these stones are able to blend in seamlessly with the surrounding area, making it look like they belong there. You also don’t need to worry about them needing to be replaced every few years as they are able to stand the test of time against water, wind, and foot traffic, all of which are known to cause erosion.

Crushed Stone (¾”-2”)

Crushed stone, particularly those from ¾”-2” provide a stabilizing base for paths, slopes, and graded areas. The result of this is a firm surface that has fantastic drainability capabilities, and that can hold its own against heavy levels of foot traffic. So, no matter whether it’s rain or shine, your path, slope, or whatever graded area you’re using this for will be safe.

The angular composition of these stones lock together under compaction, creating a strong structural support for the soil, without stopping the water from passing through. As the water is still able to move freely, this reduces the runoff water, and reduces erosion overall.

It’s for this reason that it’s such a common choice to be used under paths, in landscaping grading, and as an embankment stabilizing gravel. It’s long-lasting as it’s largely weather resistant, it doesn’t create issues with retaining water, and it enhances the overall stability of the area. In addition to this, it’s also a fantastic choice for leveling uneven terrain, especially if you’re going to be using this area to place something on top of it. As we’ve mentioned, it has fantastic compaction properties, and this ensures a level, firm surface, making it an excellent choice.

Gravel For Light Duty Slope Control (½”-1 ½”)

For those working with more gentle slopes, in garden edges, and smaller embankments, which means that the need for slope control is only light - gravel should do the trick. With options from ½”-1 ½”, you can find something that will suit your slope control needs. Using gravel like this, you can level out the space, especially if it’s a garden. Look at the different sizes, and see which one is more compatible to provide you with the strongest possible surface. Now, we know that gravel and stones, especially smaller ones, don’t compact the way that most would like, however if you manage to get angular gravel, these pieces will interlock, and create that firm base that you need for more support for your slope.

What gravel does do for light duty slope control, however, is create a more stable environment in the soil by assisting with drainage and controlling the water flow, as well as adding mass to the slope, which creates more resistance and reinforces the surface. Thanks to these angular pieces interlocking that we mentioned above, this creates more friction, which makes the area less likely to shift. If you were to use another option such as pea gravel, you wouldn’t get this benefit and your slope would still be unsteady and unbalanced.

Decorative Rock For Surface Stabilization

Decorate rock for surface stabilization offers aesthetic and functional benefits, enhancing the overall appearance of the landscape, while also helping manage issues such as soil displacement. Using decorative rock, you place a layer over the exposed soil, which helps protect it against erosion from things like foot traffic, wind, rain, and more. Overall, this keeps the ground surface intact, reducing any kind of maintenance needs, while also ensuring that the space still looks attractive.

The weight and texture of the stones that you choose will help to anchor the loose soil in place, which ensures a more stable surface. Your soil won’t be flying around everywhere, and it will remain in place, with the rocks pressing it down.

The only real downside to decorative rocks for surface stabilization is that if you’re in an area with heavy runoff, then it’s possible for these stones to be washed away. The force of the water coupled with gravity, adding in the foot traffic make it hard for them to stay in place, and they can quite easily be moved, even if they lock together in the ground to create that friction needed for stabilization. This is why it’s not the best gravel for washout areas, and instead you may want to look at alternatives if you know you’re in a high risk area.

Use the information that we’ve given you above to determine what the best course of action for you is. If you’re a small landscaping business chances are you’re going to need to work with all of these at one point or another, so it’s crucial to keep in mind what is best for what project. Take a look around our website and see what products we have available. We are a proud supplier of construction owners, landscapers, and even the general homeowner who just wants to get their property sorted once and for all. Find the right stone for slopes right here!