What Is Riprap? And Why It Will Have Your Shorelines Rocking!

Riprap sounds like the name of a new style of music. Actually, it's a material used to prevent scouring and erosion along shorelines. You may have heard it called by other names like shot rock, rock armor, or rubble.

No matter what you call it, if you have property that's along a river or lake, a riprap installation may be the answer you've been looking for.

What Exactly Is Riprap?

The term "riprap" refers to rocky material placed along shorelines, around bridge foundations, and on steep slopes to protect the area from erosion and scouring. The rocks used can range from 4 inches on the low end and go up to over 24 inches on the high end.

It's important to use a mixture of sizes to create a tight interlock for maximum protection. Clean rocks with sharp edges form the most cohesive barrier.

The size of the material used on a particular project depends on a few things:

• The area to be covered
• The steepness of the slope
• The speed of the water

Larger material withstands more force, while smaller material helps protect the soil underneath from being scoured away. Adding a membrane over the soil below prevents it from moving up through the rocks.

From an aesthetic point of view, riprap can look natural, especially with local vegetation growing amidst the rocks. In time, wildlife often create homes in among the rocks. It can create an entire habitat, depending on the size of the project.

Wildlife can have trouble climbing up the rocky slope. Adding smaller rocks and soil among the larger material can make it easier for them.

Where Is Riprap Used?

Engineers, environmentalists, and architects like to use riprap anywhere they want to protect a shoreline or structure from moving water. Some common applications include:

• Around bridge pylons and slopes
• On the outer edge of river bends, slowing down the water's power
• Along the edge of lakes to prevent erosion due to waves
• Paired with walls to prevent undercutting of structures and utilities

Riprap is also commonly used to create spillways. Excess water spills over the banks of a river or lake and runs down the spillway to prevent or mitigate flooding and shore erosion.

This material is not a good option for securing slopes that are steeper than 2 feet of horizontal extension for every 1 foot of drop. A steep slope creates a situation where rocks can fall dislodge and fall down the slope. This opens up the exposed area to water erosion.

How Is Riprap Used?

The traditional use of riprap is standalone. It's basically a stack of rocks that starts below the water line and moves up the embankment. The faster the water moves, the thicker the layer of riprap has to be, to withstand erosion.

In areas with fast water movement, the amount of rock required can be extensive. This leads to a higher cost. Where large rocks aren't locally available, the cost can be even higher.

To lower costs, partially grouted riprap has become an accepted alternative to traditional stacking. The contractor's crews uses a cement-adhesive mixture to adhere smaller rocks together, forming a stability matrix.

With this method, less material is required without compromising the structural stability and durability. It offers a considerable cost savings on projects where material isn't readily available.

If you have a shoreline that's eroding, a riprap installation could solve your problem permanently. It's important to have an expert take a look and recommend a solution that's both environmentally sound and financially doable. Give us a call today at 941-479-7811 or email us at admin@crosscreekenv.com to request a quote!