Rip rap is defined as loose stone that’s laid down on shorelines in order to protect against erosion while also providing a pleasant aesthetic. Though just strictly defining this material in terms of rip rap erosion control does not do justice to how beneficial this material is in numerous ways. Attractive, affordable, easy to install, and incredibly protective, rip rap has been around for quite a long time.
Going back thousands of years, civilizations like the ancient Greeks and Romans would adorn their shores with stone in order to preserve the area and stave off erosion. In 1822, the word “riprap” was coined, which was meant to denote a “stretch of rippling water,” explicitly referring to the waves crashing against the shoreline, taking more of the material away each time. Over the years, the only thing that has changed about rip rap is its spelling.
For people who live on the shores of Lake Michigan, this material may offer some of the best protection you could expect against the enormous lake, while also adding a very attractive aesthetic. Lake Michigan’s surface area is over 22,400 square miles, making it the second-largest Great Lake while also one of the biggest lakes on the planet. It has thousands upon thousands of miles of shoreline, every square inch of which will be eroded away by the lake unless protected.
How Does Rip Rap Work?
For people interested in this material, they first want to know how it works. A couple of common misconceptions that people have about this material may help to explain it in better detail.
1) Isn’t rip rap just rocks tossed onto a riverbank or shore?
There’s actually much more to it than that. While these stones do not have to be set necessarily like paving stones, they’re also not just thrown onto the shore. The idea is that rocks absorb the energy of the water, so that it’s deflected, while the space between the rocks actually creates helpful channels that will divert the water away in multiple areas, lessening the impact of the water even more. One can think of it much like building a rock fence, whereby the materials are stacked according to size for a systematic approach to a solid structure. The same principle applies here, as the stones are placed with organization in order to absorb energy and deflect impact.
2) Any rocks will do to keep dirt and sand from eroding away, right?
This is also a misconception. Water can easily erode stone. Just look at the Grand Canyon. It’s not the rocks themselves that are necessarily standing up to the power of erosion. It’s the system in place that’s provided by rip rap, which works to absorb energy while simultaneously deflecting it and channeling it away. The rocks themselves are not immune to erosion. The system itself, created with quality construction, spreads the impact out over distance, which greatly reduces the effects erosion will have. Overall, this gives rip rap some serious benefits.
Many people have a lot of questions about rip rap. Let’s tackle some of the most frequently asked below.
Frequently Asked Questions about Rip Rap for Shoreline Protection
How Effective is Rip Rap?
Rip rap is the go-to method for shorelines, especially along lakes, which don’t have the same tidal force worries as oceans, yet still deal with a lot of flooding and changing water levels. It is an incredibly effective method to prevent erosion, though also has a lot of other added benefits. For instance, rip rap looks aesthetically pleasing and it can even help keep sediment from building up, which makes the water much clearer.
In terms of shoreline protective methods and materials, rip rap is very effective. Another benefit is that rip rap is also cost-effective.
How Does Rip Rap Stop Erosion?
Erosion takes place due to water pulling away materials from contact with the shoreline. It happens slowly and over time, though can also happen more quickly during big storms, floods, etc. Rip rap provides a protective layer that keeps the water from making contact with the soil, thus it’s not the shoreline being eroded; it’s the actual rocks being eroded, which happens much more slowly. The large rocks absorb energy while diverting the water into smaller channels with smaller stones. This spreads out the energy and lessens its impact while keeping the shoreline protected well.
Why is it Called Rip Rap?
Back in 1822, American English started using the word “riprap” as a nautical term, which referred to a stretch of rippling water, caused by underwater elevations. “Riprap” was more or less a literal take on what was happening. Over time, the word transformed to rip rap, or rip-rap, from its one-word original start. “Rap” referred to a blow or strike, whereas “rip” was a literal term for what the phenomenon looked like, a ripping of the water. When waves crash into the shore, it has this same appearance as the riprap from underwater elevations, so the materials used were in fact to stop the force of the riprap, and the name just stuck for the rocks used to create the protective system.
How Do You Put Rip Rap on a Shoreline?
This likely isn’t a DIY type of job. One should consider contacting the professionals to have riprap installed. The process starts with grading the shoreline, in order to create a stable, compact surface on top of which rocks are going to be placed. It starts, in most applications, with the setting of much larger stones, called anchors, on the bottom row, and working up and placing relatively large stones and ensuring that they’re set well into the ground. The spaces between the large stones are known as channels, and these channels need to be filled up with smaller stones.
The reason for this is that you do not want water actually making contact with the shore between the rocks. What this will do is erode the edges out, cause the stones to become loose, and they’re going to fall out of place or be pulled out in no time at all. Though by filling those channels up with smaller stones, the size of gravel, water is not able to erode away from the surface of the shore. This creates a very good layer of protection.
How Do You Spread Rip Rap?
Spreading the rip rap, as the process touches on above, involves grading the land. You do this by ensuring it’s compact, and then placing a layer of gravel, spread all over the entire area where the rip rap will go. This allows for extra protection, so the soil doesn’t start seeping through the rip rap layer. Then it’s a matter of really spreading the rocks around with the hands. It’s a very labor-intensive job, but none of the stones are large enough to require machinery. Maybe something to transport a lot of rocks and/or gravel at once, but likely not any sort of heavy machinery to lift and spread the rocks for a shoreline area.
How Do You Calculate Rip Rap Rock?
There are two ways by which one can calculate rip rap.
1) The first method requires those math skills to make an appearance. What you’re doing here is actually calculating how many tons of rocks you’re going to need for a surface area. So, what you will do is measure the amount of cubic yards you have with an area that needs to be covered. You do this by a density equation. For example, if it’s 15 cubic yards, multiply that number by 2,700. This gives you 40,500 pounds. Next, divide that end number by 2,000, which is how much a ton weighs, and that gives you a total of 20.25 tons you will need.
2) The much simpler, faster and more efficient way: Contact the experts. Reach out to the professionals in the area who make it their business to work on these sorts of shoreline projects. This is by far and simplest way to calculate how much rip rap rock you’re going to need.
How Much Does Rip Rap Cost to Install?
Every job is going to be a bit different, and so there is no universal cost. However, to give you a decent idea of what you will be looking at, the average cost for rip rap on today’s market is $35 to $50 per square yard ungrouted, while a grouted option will cost on average $45 to $60. You will not know for sure until which point you do all your measurements and receive your estimate.
How Much Area Does a Ton of Rip Rap Cover?
One ton of rip rap, whose rocks range from 3 to 8 inches in size, will cover about 35 linear feet, and 3 feet of width. So, all told, likely about 12 or so square yards.
These are some of the most frequently asked questions regarding rip rap, along with some of its advantages. Though like the waters of Lake Michigan, everything has an ebb and a flow. There are also some disadvantages of rip rap, although not as many and not as major.
Disadvantages of Rip Rap
1: More Expensive Than Some Options
While rip rap erosion control systems are quite affordable, they’re simply not the cheapest way to go. For people who are really on a budget, they may look into vegetated slopes, covered in a variety of plants. While this isn’t nearly as protective, and can also be seasonal only, it’s still a cheaper way to go than with stone.
2: Not Helping the Ecosystem
Let’s be very clear here, rocks are not harming the ecosystem. However, one could easily argue a disadvantage of rip rap is that it’s also not helping the ecosystem thrive. Because it’s stone and not foliage or vegetation, it’s not going to act as a home to the many varieties of insects and even smaller aquatic animals (frogs, salamanders, etc) that could build a home in a vegetated slope. With this sort of rip rap disadvantage, it becomes a matter of personal taste and also how responsible you feel for adding to the ecosystem.
3: It Doesn’t Last Forever
Technically speaking, rocks can theoretically last many thousands of years against common water contact like the tides of Lake Michigan. However, you have to be aware that there’s a system in place, whereby stones are anchored in and set into place. As water pulls smaller rocks out of place, larger rocks eventually work themselves loose. So while a quality rip rap seawall will last a few generations, in all likelihood, they are not permanent.
So, there it is. You have the advantages of rip rap, and the few disadvantages. As can be seen, the pros far outweigh the cons. There exists no better system than rip rap for erosion control out there today. Though while it’s incredibly protective on that front, it also adds to property values due to the aesthetics, creates a more tranquil atmosphere, and will even help keep the water cleaner.
Perhaps the best part of all about rip rap protection is that people who live on the shores of Lake Michigan have easy access to services that can assist you from start to finish in protecting the shoreline.