Preventative Measures for Stormwater and Erosion Control

With more frequent and powerful storms, erosion issues and polluted stormwater runoff is an ever-increasing concern. However, there are preventative measures that can significantly assist stormwater management and erosion control.

What is Stormwater Runoff?

Stormwater is simply rain that has hit the ground. In nature, rainwater from storms and snowmelt is absorbed into the ground. Once there, it can naturally be filtered through soil and plants.

In developed areas, however, paved surfaces prevent water from being absorbed into the ground. This water pools up and runs into storm drains. Unfortunately, most storm drains run directly into oceans, lakes, and rivers.

Why Manage Stormwater?

According to the EPA, stormwater runoff can contain nitrogen and phosphorus pollutants from fertilizers, pet and yard waste. It can also contain trash, heavy metals, and any other contaminants that were already on the ground before the rain fell.

In most cases, these pollutants are not filtered out before the stormwater makes its way into local bodies of water. This means that poorly managed stormwater runoff is likely polluting rivers and lakes with each passing storm.

This can cause damage to the natural habitat, the fish and other aquatic life living within it, as well as the people who swim in these waters. Not only is the damage to habitat a concern, but sometimes stormwater runoff can end up in the aquifers that are meant to supply clean drinking water to the city. This water ends up entering the aquifer before having an opportunity to enter a wastewater treatment facility.

As you can see, managing stormwater runoff is good for the environment and the people living in it, but these aren’t the only reasons for managing it. In most parts of the country, there are laws requiring businesses, developments, and even homeowners to manage their stormwater runoff.

New developments are almost always required to control and treat stormwater before it leaves their property.

Preventative Measures to Reduce Stormwater Runoff

There are a number of preventative measures that can be taken to reduce stormwater runoff. These include:

· Stormwater runoff can be captured and released later.

· Natural watersheds can be used to absorb water before it is sent into local water sources.

· Low impact development can be used to replace lost natural watersheds.

· Treatment facilities can be used to help clean polluted runoff water.

When it comes to managing stormwater runoff, there are three main goals. The idea is to slow the water down, spread the water out, and sink the water into the ground.

How Homeowners Can Manage Stormwater Runoff

Homeowners can slow water down in their neighborhoods by making use of rain barrels to capture water before it has the chance to hit the ground, such as in the case of collecting water from downspouts. They can then use the water for irrigation at a later time when the soil is not oversaturated.

They can also modify their yard to slow down the flow of water and to help the ground absorb more of it. This can be accomplished by using permeable pavers, rain gardens, and the use of plants that help to facilitate the flow of water into the ground.

What Businesses Can Do for Stormwater Management

Larger developments and businesses can make use of biological filtration systems to help slow down and filter water naturally. An example of this would be a grass-lined ditch with an inlet structure and an outlet structure. In this case, the water is slowed and absorbed by the grass in the ditch.

You’ll also notice that some developments have their own man-made lakes and watersheds. If you’ve ever driven by a new community with a man-made lake built into it, you’ve probably witnessed stormwater runoff management in action.

How Governments Can Manage Stormwater

Local governments can also help to slow the flow of stormwater as well. They can do this by preserving or re-building natural watersheds. If this isn’t an option, they can divert stormwater runoff to water treatment facilities.

For example, Washington DC has a series of underground tunnels that have been built to send stormwater runoff to water treatment facilities before it is sent out into the local rivers.

A more basic example of governments working to control stormwater runoff can be seen next to roads and highways. Often-times roads will have trenches built alongside them. These were built to help collect and manage the water that runs off these roads.

Erosion Control

Another by-product of stormwater runoff is erosion. Erosion is the process of soil being removed from the surface of the landscape. The leading causes of erosion are running water, ice, and wind.

Why Erosion Control is Important

There are many reasons erosion control is important. Among them are:

· Erosion can destroy waterfront properties.

· Erosion can be responsible for sedimentation.

· Wildlife can be adversely affected by erosion.

Coastal towns spend millions of dollars each year to protect and rebuild their beaches. If they didn’t do this, the ocean would swallow the nearby homes and businesses.

It isn’t just beaches that are affected by erosion. Erosion is responsible for increasing the size of some lakes and rivers while decreasing the size of others.

In the case of increasing the size of lakes and rivers, stormwater runoff flows into lakes and rivers, and they become deeper and broader. At the same time, the fast-moving stormwater can remove the soil from one location, carrying it downstream. This removal of the soil increases the size of the stream or river.

The size of lakes and rivers can be decreased through sedimentation, which is a byproduct of erosion. This is when eroded soil is pushed into the water, making the body of water shallower or narrower.

Sedimentation can cause other problems as well. Sediment build-up can block storm drains. This puts an even heavier burden on the remaining storm drains and causes further erosion issues.

Erosion can destroy wildlife habitats as well. For example, the depth of a lake can significantly impact the fish living within it. For instance, some species of trout will die off when a lake becomes too shallow.

Preventative Measures to Reduce and Control Erosion and Sedimentation

Here are a few of the preventative measures to control erosion and reduce sedimentation issues:

· Erosion control mats can be used to hold soil in place.

· Vegetation can be grown to provide a permanent barrier against erosion.

· Trenches and swales can be used to catch sedimentation.

· Retaining walls can be used to hold soil in place permanently.

Both erosion control and sediment control can be used together to eliminate the harmful effects of erosion completely. The key to this strategy is to apply the best erosion control measure first and then to add sediment control when necessary.

Temporary Erosion Control Measures

The most common temporary control measure for erosion is the erosion control mat. This mat is typically made from biodegradable materials such as straw, jute, or coconut fibers.

An erosion control mat is a great temporary erosion control measure because vegetation can be grown through it. Erosion control mats and vegetation control work hand in hand, as vegetation can be fully established before the fiber mat has degraded. We will talk more about vegetation as an erosion control measure in the next section of this article.

Another temporary erosion control method is to use hydromulch. Hydromulch is an excellent temporary control measure because it can quickly be applied with just a truck and a hose. The drawback is that it does not last long and the installation will require the use of water.

Permanent Erosion Control Measures

Vegetation is an excellent long-term erosion control method. The reason vegetation controls erosion so well is because the roots of the vegetation grow directly into the soil to hold it in place. Carefully planted vegetation will require minimal maintenance and can last indefinitely.

It is, however, that the installer verifies that the vegetation has taken root before the control mat has lost its usefulness. Plants do not always grow as they are expected to and, in some cases, a second mat will need to be put in place, and new vegetation planted before this erosion control method can become permanent.

For a plant to be useful as an erosion control tool, it needs to have deep roots. Additionally, it should be able to spread and reproduce itself so that it does not have to be replanted each year.

A more permanent solution to erosion is the building of a retaining wall. Retaining walls are a good choice when vegetation is not strong enough to stop erosion from occurring.

Sedimentation Control

While it’s always best to prevent erosion from occurring, it is important to recognize that it isn’t always possible. In these cases, it is best to combine erosion control with sediment control.

A good sediment control plan will catch sedimentation and hold it so that it can be removed before it ever has a chance to reach a storm drain, lake, or river.

There are a few different ways to catch and trap sedimentation. One method that is commonly used is the creation of a swale. A swale is a trench that sits after the bottom of the erosion tool and before a solid barrier.

The swale is often lined with rocks or gravel. This helps trap sedimentation while allowing water to still flow through the area.

The barrier could come in the form of bricks, rock socks, or even asphalt. The goal of the barrier is to trap the sedimentation within the swale so that it can be removed in between storms.

For this reason, it’s important that sedimentation barriers be checked and cleaned regularly.

Using Drones for Stormwater Management and Erosion Control

Drones provide a significant advantage for both stormwater management and erosion control. Drones can provide accurate volumetric measurements of how much water is in a drainage basin, as well as how much volume is available before overflow becomes an issue. With this precise information, planners can make better decisions about how much water to release downstream, as well as how to control inflow into the watershed.

As in the case with watershed volumetric measurements, drones can be used to 3D map the terrain and locate where erosion is already occurring, or where there is the highest potential for erosion to occur. Of course, the worst-case scenario for erosion is a landslide, or slip. Solspec has specially designed software that works in conjunction with their drone imaging to accurately predict where slips may occur. Armed with this intelligence, municipalities and pipeline companies can address a potential slip hazard before it becomes a reality.

In Closing

There are many ways to control stormwater and erosion, and the best method to use will vary from location to location. One thing we know for sure though is that stormwater and erosion will always be an issue that needs to be addressed.