Ponds and stormwater basins can be great resources to have on a property, and they can provide great benefits for the surrounding area. Regular ponds can be a nice attractive feature for a home landscape and can provide a place for recreation. Stormwater basins act as a water quality feature in areas such as subdivisions by filtering out any pollutants and protecting nearby streams as a result. There are two types of stormwater basins, wet ponds (retention basins, always have water) and dry basins (detention basins, normally bowl-shaped depressions of grass that hold water for a few days after it rains). In this month’s article in the Development Digest, we will dive into a service that we at Warren County SWCD offer to measure the depth of ponds to ensure they have the correct depth needed to function properly. This service is one we offer for all types of ponds; however, we will specifically be looking at newly constructed stormwater retention basins here.
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Having the correct depth is very important when designing a stormwater basin. If a basin is designed incorrectly and is too shallow, it may not provide enough storage for incoming water which defeats the purpose of the basin and may have negative effects downstream. Even with a correctly designed basin, the basin may fill up with sediment during construction, and if that sediment is not removed, this will affect the water depth, and as mentioned above, decrease the storage. During construction, sediment basins need the sediment removed once it reaches ½ of the sediment storage zone and before project completion as well. It is important to measure the depth of the water in a stormwater basin to ensure it is the correct depth and sediment has not filled in the bottom. Here at Warren County SWCD, we can assist with getting an estimate of the depth by providing a free service using a depth finder.

Depth finders are commonly found in the realm of fishing and used by fisherman to get an accurate depth of the water column for fishing purposes. We have found out that we can use a simple depth finder to find the depths of ponds and basins to assess the health of that water feature. We will come out to any pond or stormwater basin per request and use our depth finder to give a good estimate on how deep the pond/basin is. We provide this service because it is important to keep basins healthy and keep the designed capacity to make sure the basin still has its storage and water quality abilities working. Any construction project that is nearing the end and has a stormwater pond should be checked for water depth before being turned over to the next owner. Here at WCSWCD, we would be happy to come out and provide a free depth check using our depth finder.

We also provide this service to HOAs, free of charge, to determine if it is time for the costly dredging project you may be considering. If you are having excessive algae blooms and fish kills in your retention pond, it might be an indicator of a shallow water column. Ohio Department of Natural Resources recommends a pond with a minimum water column depth of 6-8 feet deep to provide a healthy habitat for fish.

It can be costly to dredge a pond of muck that accumulates naturally over time, A rough estimate of when this is needed is 10-20 years after completion or from its last dredging. It can easily cost up to $100,000 or more to completely dredge a large retention pond, so you want to be sure if it is time to do so. We are happy to come out and collect some rough estimates of pond depth and health and we can also provide some contacts for pond maintenance and dredging contractors to point you in the right direction.
 
If you have general pond/basin questions or have questions about our depth finder or want to schedule a site visit with us, please give us a call at (513) 695-1337.
 
Article written by Seth Byerly, Urban/Agricultural Technician
 

​Don’t let stormwater dig a hole you can’t get out of!

​Fast moving water pouring out of a pipe can quicky lead to erosion. Planning ahead and utilizing rock outlet protection can save future maintenance headaches. In this month’s article we will see where this practice is useful, consider design, and review maintenance considerations. Let’s start by identifying where the practice is helpful.
Rock outlet protection can be useful where discharge velocities from a channel, storm drain, or culvert are high enough to cause erosion. The practice can be applied for the following outlet types:

​For design of the rock outlet protection, assume the most severe soil and vegetation cover conditions. The size of the watershed and topography should also be given serious consideration. Rock outlet protection is not intended for slopes greater than 10% or at the top of cut or fill slopes.
Caution should be used if flow rates out of the discharge pipe will exceed 100 cubic feet per second (cfs) for a 10-yr.-fequency storm. Utilize the NRCS Technical Release 55 (TR 55) or other suitable method to determine peak rate of runoff. The outlet protection needs to be stable for the velocity of flow expected from a 10-year frequency storm event. While level spreaders are helpful in conjunction with outlet protections, we will focus on the design of the rock outlet. The width of the outlet should be the width of the headwall or 4 feet wider than the pipe diameter (2 feet on each side of the pipe). The elevation of the downstream end of the outlet protection needs to be equal to the elevation of the receiving stream. The necessary length of the outlet protection and the rock size can be determined from the following figure. 

Larger diameter pipes will require larger rock diameter, a greater thickness for the rock layer, and additional length for the rock channel. The rock riprap needs to be well graded and be placed to obtain a solid and compact layer. Filter or granular bedding is needed beneath all riprap to prevent underlying soil from eroding. Larger size riprap will likely require a thicker bedding layer or 2 different sizes of bedding. Geotextile use can help prevent piping of soil. Care should be taken to properly anchor the geotextile. A properly designed and installed rock outlet protection will help to reduce future maintenance needs.
 
Maintenance will help to protect the riprap, vegetation cover, and associated structural components. The following are key to proper maintenance.

• Determine a responsible party to inspect and maintain the outlet protection.
• Missing riprap should be replaced as soon as possible.
• Protect the outlet from damage by equipment and traffic.
• Fertilize and mow area vegetation to keep a healthy cover.
• Seed and mulch any bare areas that develop.
• Remove sediment and debris.

 
If properly designed, installed, and maintained the rock channel outlet protection should function for decades to come. Lack of proper outlet protection will require more extensive and costly repairs in the long run. Feel free to reach out to our office at (513) 695-1337 if you have any questions regarding rock outlet protection.
References

1. Urban Hydrology for Small Watersheds (TR-55), United States Department of Agriculture Natural Resources Conservation Service. June 1986. Web link for this publication is available at:

https://nationalstormwater.com/wp-content/uploads/2020/07/Urban-Hydrology-for-Small-Watersheds-TR-55.pdf

1. Rainwater and Land Development Manual (Chapter 6.1), Ohio Environmental Protection Agency. May 2025. Web link for this publication is available at: https://dam.assets.ohio.gov/image/upload/epa.ohio.gov/Portals/35/storm/technical_assistance/6.1_Outlet_Stablization.pdf

Article by Travis Luncan, Urban Technician

Water! Water is all over the place, and it moves wherever it wants. Water has the ability to cause major problems at high velocity during certain times such as high rain events that cause flooding. Erosion is an unfortunate result of the damage that moving water can cause. Erosion can be especially present on construction sites due to the exposed sediment and piles of material, and so it is important to know the different types of erosion and the best management practices that can be used to prevent sediment from eroding off site and into the waters of the state. In this month’s Development Digest, we dive into the most common types of erosion found on construction sites.
Generally, there are 4 common forms of erosion that are caused by the movement of water on exposed sediment on construction sites. These 4 forms are splash erosion, sheet erosion, rill erosion, and gully erosion.

• Splash erosion: Splash erosion is very simple and straight forward. Anytime a raindrop hits the ground, specifically exposed sediment, it can hit the sediment and loosen up the soil particles. This is an issue because when the soil particles get loosened, flowing water can easily carry them on downstream. Splash erosion is the first step in the process that if unchecked can lead to very large and costly amounts of erosion.
• Sheet erosion: Sheet erosion is defined as the uppermost layer of the soil being gradually removed do to some environmental factor. The most common cause for sheet erosion on construction sites is rainfall. Rain hits the bare soil loosening up the soil particles and the water then carries those particles off site through runoff.
• Rill erosion: Rill erosion is similar to sheet erosion; however, the erosion is a little more defined into smaller channels. In this type of erosion, the entire surface of the soil is not necessarily being eroded away because the water is forming into small paths and eroding sediment from those concentrated areas. Rill erosion can lead to much worse erosion if left unfixed.
• Gully erosion: Finally, the last type of erosion is the biggest and most easily seen type of erosion. Gully erosion forms from all of those little rills that have been carved into the ground by the water. Eventually, all of those rills meet somewhere and all of the water from the rills get combined into one big channel. This channel is called a gully. A gully has a higher velocity than rill erosion due to the greater amount of water flowing through, and because of this, a gully can be, and in most cases is, the deepest type of erosion. In general, gully erosion can be about 6-12 inches minimum, and at most can be many feet deep depending on the underlying soil and the different soil layers. Once gully erosion starts, it can get much bigger and bigger, and if left untouched and can cause damage to the landscape and anything that could be affected by the land being lost to flowing water.
  

During construction, it is very important to utilize the BMPs (best management practices) available to all of us to prevent erosion from happening. The most important practice available is stabilization. Whether it be through phased grading to minimize disturbance, keeping straw covering the ground during temporary pauses in work, or immediate stabilization of a site at final grade, getting exposed sediment covered up and stabilized is the best thing we can do to minimize the risk of erosion. There are also other practices that we can use if stabilization is not an option due to ongoing construction. BMPs such as silt fence, mulch berm, and filter sock are great for the perimeter of a site and can be used to slow down water and prevent any eroded sediment from moving further downhill and causing more damage. Check dams consisting of rock are great in areas of concentrated flow to slow down the velocity of water and prevent erosion. Overall, limiting the area of disturbed soil on a site can go a long way to limit the amount of erosion that may occur. Being mindful and aware of the work that we do to the land, and what effects it might have, is important. The less care we have about sediment and erosion control, the more damage erosion can do to the land and to the water, so hopefully by now having a basic understanding of the types of erosion out there, we can do our part as humans to protect the soil and keep it in place.

Have questions about sediment and erosion control, or just about erosion in general? Please contact our office and we’d be happy to answer any questions you may have!
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Article written by Urban/Ag Technician Seth Byerly

Rainwater rolls off the landscape as a trickle, stream, or river. For a light rain event the drainage channel may not matter that much. For a moderate or heavy rain events the design and condition of the drainage channel becomes more critical. A grass swale is one of the stormwater conveyance methods identified in Ohio EPA’s Rainwater Land Development Manual. In this article we will look at good design, stabilization and maintenance of grass lined swales. Many drainage assistance calls we go on involve a swale. Common issues we receive calls on are erosion in the swale, overflow of the swale, and modification/blocking of the swale. Most of these issues are preventable with proper design, building, maintenance of the swale and education of residents/HOA’s.

Design starts with looking at runoff. The area drained, soil types, land use, topography and historic rainfall data all play a role in determining the swale size and how it is stabilized. A swale should be designed to carry the peak rate of runoff from a 10-year flood before it overtops.  If the swale is designated as a Flood Route, it must be designed to handle a 100-year rain event. While it would be well beyond the scope of this article to go through all of the calculations, NRCS Technical Release 55 (TR 55) is one suitable method to determine peak rate or runoff. Grassed swales designed to protect residences and businesses need to have out of bank capacity to carry the peak rate of runoff before water can flow inside adjacent residences or businesses.

Shapes of drainage swales can be parabolic or trapezoidal. The parabolic channel closely approximates natural flow conditions, but design and construction are more complex. Trapezoidal channels are preferred where there will be a large quantity of water or high flow rates. Side slopes that are 3:1 or flatter are recommended.

Next to consider is the channel’s stabilization and resistance to erosion:
Clay soils, which are common in Warren County, offer moderate protection from erosion but good protection once vegetation is established. Sod or seed and matting are preferred to establish vegetation. The grassed swale should be vegetated as soon as possible after reaching final grade. Waiting makes it more difficult to get good stabilization. Delays in stabilizing the slopes will also cause maintenance issues that will later need fixed. Stabilize upslope areas to prevent sediment from washing down and filling in the swale.

Check dams may be incorporated to decrease water flowrate, to reduce erosion, and to allow grass to establish. The rock check dam should be lower in the center so that water does not flow around and erode the edges of the swale. Check dams are often temporary measures. It is good to plan to determine when the check dam will be removed.

For sites with prolonged flows, a high-water table or seepage problems; a subsurface drain or rock-lined waterway may be incorporated. Grassed swales should also have a stable outlet with adequate capacity to prevent ponding or flooding damage.

Beyond design and construction of the swale, owners should consider ongoing maintenance. Most important would be to ensure that residents don’t block, modify or build in the swale. Grass growth should be monitored to insure a vigorous stand of grass. Protect the swale from compaction or damage due to equipment or traffic. Fix damaged areas immediately. With good design maintenance and stabilization, a swale will protect property and prevent future maintenance needs.
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References:

1. Urban Hydrology for Small Watersheds (TR-55), United States Department of Agriculture Natural Resources Conservation Service. June 1986. Web link for this publication is available at:

https://nationalstormwater.com/wp-content/uploads/2020/07/Urban-Hydrology-for-Small-Watersheds-TR-55.pdf
   2. Rainwater and Land Development Manual (Chapter 6.7), Ohio Environmental Protection Agency. May 2025. Web link for this publication is available at: https://dam.assets.ohio.gov/image/upload/epa.ohio.gov/Portals/35/storm/technical_assistance/6.7_Open_Channels.pdf

Contaminated water that runs into natural streams and river can be very harmful for the biodiversity of an ecosystem and all of the plants and animals in it. There are many different sources and ways that water can become contaminated, and one specific way is from dumpsters, and the waste in those dumpsters. Many commercial dumpsters have a plastic lid that flips up and down to cover the waste. However, a lid is not necessarily as commonly seen on construction site dumpsters. In this month’s BMP Blast, we will discuss the importance of covers on construction site dumpsters.
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All construction sites have some sort of dumpster on the site to dispose waste. This waste can range anywhere from crushed concrete, paint cans, oil containers, old batteries, whatever people throw in there. Contained in a dumpster setting, this waste can not cause much harm to the environment around it. However, if water finds its way into the dumpster, the water is able to wash contaminates off of the waste and out of the dumpster. Additionally, when the dumpster gets picked up and removed, the driver will not want to haul away something filled with water, so the water may be dumped out. All of that water being dumped could contain chemicals, and all of the water and chemicals will reach the nearby stream all at the same time, and this could be very harmful. There is a simple solution to prevent this type of pollution from happening; dumpster covers.

Dumpster covers are a simple best management practice that can be put on top of a dumpster to ensure unwanted rain doesn’t seep into the dumpster and washout any chemicals. Covers are fairly low cost, easy to manage, and provide a very large benefit that prevents any type of mess or disaster for the environment and ecosystems. We realize that it is convenient to have an open dumpster that waste can be thrown into at any time of the day, and a cover may be annoying to open every single time something needs to be disposed of. A simple solution would be to ensure that the cover is on only at the end of each workday and before any rain event starts. The dumpster can remain uncovered during the day, and covered at night and during rain, and this would provide an effective cover to contain pollutants. By using this simple BMP on construction site dumpsters, we can ensure that the project stays in compliance with regulations, and we can ensure the site doesn’t contribute any harmful pollutants to the neighboring environment.
 
If you have any questions regarding dumpster covers, or any other construction site BMP, please feel free to reach out to our office at (513) 695-1337. 

~Article by Seth Byerly, Urban Technician

This month I was on site at Arbors at Grandin Road for my routine monthly inspection. I noticed how consistently they are on top of their sediment and erosion controls. Stabilizing areas early on is the number one Best Management Practice to prevent erosion in the first place by preventing sediment from washing downstream. The sediment basin was also stabilized early on, as soon as it was at final grade. This helps prevent rill erosion on the banks, for rill! This is super important because once erosion occurs and sediment washes into the basin, it is very difficult to remove the fine-grained sediment from the water column. The skimmer device cannot filter all of it out. So, stopping erosion before it happens is the way to go.

From the design and SWPPP review phase, to grading, implementation of sediment & erosion controls and now into the home building phase, Arbors at Grandin Road has done their part for sediment and erosion control. It’s been great to work with everyone involved with this project and see it come together. Future phases will be underway soon and I look forward to seeing it all come together while making sure sediment is contained on site as much as possible.

So, this month we are giving a shout-out to the Arbors at Grandin Road Project for a job well done. From the engineers to the developers and builders, it takes everyone to stay compliant with sediment and erosion controls. Arbor Homes agrees, stating that it is important to protect the water as well as to maintain a tidy construction site while selling homes to potential buyers. So good work and thanks to everyone involved with this project!

-Justin Bedocs, Urban Specialist

Steep slopes on a construction site can lead to some problems when talking about erosion control and water runoff. Slopes greater than 3:1 allow water to quickly run down the slope leading to erosion and possible water damage downhill. In this month’s development digest, we discuss slope surface roughening techniques and why they are a beneficial practice on an exposed slope during construction.

What is slope surface roughening and what is the purpose? Slope surface roughening is the act of roughening up or raking the surface of a slope horizontally to create grooves, bumps, and depressions. These bumps and depressions on the slope serve multiple purposes including:

• Slowing down water velocity flowing down slope
• Trapping sediment that may wash down the slope
• Providing a better base to grow vegetation

Water running down a slope at a high velocity creates the potential for large soil erosion and damage, and by working grooves into the slope, the water is slowed down at every bump it reaches, resulting in a decreased velocity. The same idea is used when talking about trapping sediment. Like flowing water, the grooves and bumps create somewhat of a barrier for sediment moving downhill and some of the sediment gets trapped on the hill, which means the sediment is not flowing into the creeks and streams. Slope roughening is also good for vegetative growth because the depressions create a great place for the vegetation to establish. A flat, compacted slope creates a difficult surface for the vegetation to establish, and by providing depressions and loosening up some of that soil, the vegetation is more likely to survive and provide ground cover. In fact, according to the Ohio Rainwater and Land Development Manual, any slopes that are steeper than 3:1 are required to be grooved or tracked if vegetation will eventually be installed, so you might as well create those grooves before construction starts for soil erosion control as well!
 
Two main methods to roughen the slope are commonly used:

• Dragging a bucket with teeth along the slope
• Driving tracked machinery horizontally across the slope
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Using a bucket with teeth to drag along the slope is a very simple and effective method to create the grooves and depressions needed to slow down the water velocity. Using tracked machinery is also a good method that can lead to uneven grooves along the slope that will also help slow down water velocity. Both methods can be an effective way to roughen up the soil, however the track method may not be as good of an option depending on the soil because it could lead to soil compaction, which would not be good for vegetative growth. It is best to determine the soil type before choosing one of these methods.
 
Slope surface roughening is a tried and proven practice that works effectively to assist in the battle against soil erosion and water runoff. Whether using a bucket with teeth, equipment tracks, or any other method that roughens the slope, the creation of the grooves and depressions is a great practice to protect the soil and the water during the construction phase of a project. More information and specifications can be found in the Ohio Rainwater and Land Development Manual which is linked below.
 
Have questions about this practice, other best management practices, or other questions in general? Feel free to reach out to our office by calling us at (513) 695-1337 or emailing at [email protected].
 
Ohio Rainwater and Land Development Manual: https://epa.ohio.gov/wps/portal/gov/epa/divisions-and-offices/surface-water/guides-manuals/rainwater-and-land-development
 
Article Written by Seth Byerly, Urban/Ag Technician

"April showers bring May flowers". Those same rain showers can contribute to other types of blooms; algal blooms. Plants need sunlight, nutrients, water and a favorable environment in which to grow. Algae have similar requirements. A shallow basin allows intense sunlight to shine to the bottom and allows the water to heat up quickly. Longer spring days mean more sunlight available to the algae. Warming temperatures also contribute to the growth of the algae. Nutrients that are bound to sediments can wash into the basin from the surrounding drainage area and help drive algal blooms.
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Why does algae in a basin matter? Algae is a part of any heathy aquatic ecosystem so at normal levels they are not a problem. When one species of algae blooms, it can lead to maintenance issues and other problems. Let’s look at algae blooms and their impact on the function of the stormwater basin. Dense algal scums interfere and obstruct parts of the basin’s outlet structure, causing it to lose storage capacity or overfill. Algae that die off will sink to the bottom, decay and will eventually fill the basin with muck. This can lead to costly maintenance. 

Beyond the maintenance implications of an algae bloom, there are health and aesthetic implications. As an algal bloom dies off and decays dissolved oxygen in the water is depleted. This can lead to a fish kill. While not all algae blooms would cause a health impact, there is one class of “algae”, the cyanobacteria, that can release harmful toxins when they bloom. The toxins they release can harm pets that wade or drink the water. There can also be respiratory impacts from severe blooms.  Water quality also includes aesthetics. A homeowner who just paid $500K to move into a nice community is less likely to appreciate a basin with a thick algal scum. This can hurt real estate values in the area.

The best way to reduce the impact of a harmful algae bloom is to work to prevent blooms. This starts in the design phase. Designing a wet extended retention basin to a depth of 6-8 feet and with sufficient bank grading will reduce plant growth and algae blooms in the basin. A dry basin should be constructed so it doesn’t hold water for more than 72 hours. During the construction phase, limit the amount of sediment that flows into the basin. This sediment will have bound up nutrients and will provide the food leading to future algae blooms. Remove built up sediment in the basin, the presence of a forebay should make this maintenance easier. Stabilize the basin walls and surrounding ground with seed and straw to help lock soil and nutrients in place, keeping them out of the basin.
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Post-construction measures like keeping a vegetated buffer around the basin will help keep the sides of the basin from caving in. The taller vegetation will also discourage geese from hanging out around the pond and adding more nutrients. The vegetation buffer will act as a filter strip. Native sedges, blue flag iris and rushes are a few plants recommended as native buffers. Woody vegetation and nuisance vegetation should be discouraged. Keep grass clippings out of the basin. Bottom-up aeration can help support a healthy ecosystem and help regulate temperature. Also encourage residents to be responsible if they are applying fertilizer to their lawns. Adopting the four Rs of nutrient management for your lawn can be useful.

​Considering that fertilizer will lead to more costs, mowing, and maintenance, some may decide to forego it.  With proper design and maintenance, the stormwater basin will remain functional and be more enjoyable to have in the community.

​For more information, contact our office at 513.695.1337

​Sediment and erosion control is always a challenge on construction sites when soil is exposed to the wind and rain. As rain falls on the exposed soil, it loosens it up and begins to wash away as fine-grained sediment. Sediment is the top pollutant impacting Ohio’s streams. It clouds the water column, choking out aquatic life, and changes stream morphology by settling out in areas of slow flow. Alluvial fans are a great large-scale visualization of this (Fig. 1). As the water slows down, it drops the sediment out which raises the ground level. Water will seek a new path of least resistance. Hopefully not towards someone’s house! Sediment can change stream morphology too. Deep pools within a stream provide cool-water habitat for fish and these can be filled in as sediment is deposited. What once was a great swimming hole is now too shallow. One way we can reduce sediment discharge to Ohio’s lakes and streams is by installing sediment settling basins on construction sites. These are required by the Construction General Permit as the stormwater must be treated before being discharged from the site.

​A sediment basin is a temporary settling pond that filters runoff and releases it at a controlled rate. They can be used for sites where the drainage area is 100 acres or less. Any project that increases the impervious surface is required to have a permanent, post-construction stormwater basin, so it makes sense to install the sediment basin on the low point of a site, where it will be converted to its post-construction design at the end of the project. They should be installed as a first step to the mass grading process, so they can be functional and ready to accept sediment-laden runoff once the earth is disturbed. Since sediment basins trap sediment, the sediment will need to be removed before project completion. This ensures that the basin has the proper water quality storage capacity when it gets converted to the post-construction stormwater design at the end of the project. All these considerations should guide the design process.

​Ohio EPA’s Rainwater and Land Development Manual (https://epa.ohio.gov/divisions-and-offices/surface-water/guides-manuals/rainwater-and-land-development) is the guiding document for stormwater practices used during development. Chapter 6 covers sediment basin design. Figure 3 illustrates the various components of the design criteria, which includes pool design, embankment design, dewatering design, and spillway design. A floating skimmer device (Fig. 4) is required throughout the duration of the project to drain the water from the top of the water column, where the sediment is less concentrated. So, install the skimmer and let it simmer!

The Ohio EPA has created a sediment basin compliance tool, which we require to be completed for all projects. This tool is helpful to determine the sizing of your basin by inputting numbers relating to total disturbed area and total drainage area draining to the basin. The dewatering zone shall be a minimum of 1800 cubic feet per acre of drainage while the sediment storage zone shall be 1000 cubic yards per disturbed acre that drains to the basin. After inputting the drainage area and disturbed drainage area, it will calculate the required sediment and dewatering zone volumes as well as the orifice size and skimmer size. There is also a Water Quality Volume tool very similar to this tool that guides the post-construction stormwater design. Our office is happy to provide these tools to you upon request.
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Stabilization is not just important for upland controls, but the basin itself should be smooth graded and stabilized as a first step to the mass grading process. That way the basin can be in place before any upslope disturbance occurs to accept sediment-laden stormwater. Towards the end of the project, when the entire site is stabilized, the sediment basin needs to be converted to its post-construction stormwater design. This usually entails removing the skimmer device and installing an orifice plate to achieve the proper water quality orifice size for post-construction treatment of stormwater. As-Builts need to be completed and submitted to the Engineer of Record for the municipality.

​Sediment basins should not solely be relied upon as the only sediment and erosion control measures on a site. Ohio EPA has found that they are only about 50-80% effective at removing sediment. The finer silt particles remain suspended in the water column and are too small to filter out. That’s why a whole toolbox of SECM’s should be used on a site.  The best management practice (BMP) is to prevent erosion and sediment transport in the first place by stabilizing areas at final grade or areas that lie dormant for longer than 14 days. Ohio EPA has found that erosion control BMPs like stabilization are 90-98% effective. So, it takes multiple tools to properly handle stormwater runoff on a site. Sediment basins are a crucial part of the stormwater solution by satisfying both water quantity and water quality requirements. And don’t forget, install the skimmer and let it simmer!

For assistance, please call our office at 513.695.1337

​Article Written by Justin Bedocs

Stabilization when a site has completed construction is one of the most important BMPs that we can install to prevent erosion and sediment pollution. Stabilizing exposed sediment covers the ground from stormwater runoff, allows roots to be put into the ground to hold the sediment in place, and in general, stabilization is much more pleasant to look at than just bare dirt. In this month’s Development Digest, we will dive into a few species of grasses that can be used for stabilization, and the circumstances in which each species is recommended. 

Two different types of stabilization need to be considered when choosing grass species. Is the seeding being done temporarily, or will the grass be permanent? According to the Ohio EPA Construction General Permit (CGP), any area that will remain idle for over 14 days but less than one year needs to have temporary stabilization. For example, this means that a site that will be dormant for 9 months should be mulched and have seed put down to protect the exposed sediment. When talking about temporary stabilization, we want to have a grass that is going to pop up quick to provide that protection as soon as possible. A mixture of seed is recommended to get optimal cover. Perennial rye grass is a good species to have in the mix for sites that will be dormant for longer periods of time. Oats are a good species to include, especially during the cooler weather since they are able to grow quickly. In the Ohio Rainwater and Land Development Manual table 7.8.1 there are mixes that are great to use for temporary stabilization. Below are some of the mixes:

• From March 1 to August 15
  • Oats, Tall Fescue, Annual Ryegrass
  • Perennial Ryegrass, Tall Fescue, Annual Ryegrass
  • Annual Ryegrass, Perennial Ryegrass, Creeping Red Fescue, Kentucky Bluegrass
• From August 16th to November 1st
  • Rye, Tall Fescue, Annual Ryegrass
  • Wheat, Tall Fescue, Annual Ryegrass
  • Perennial Rye, Tall Fescue, Annual Ryegrass

For exact seeding rates, please refer to table 7.8.1 on the Ohio Rainwater and Land Development Manual which is linked at the bottom of this article. The big takeaway when choosing a species for temporary stabilization is to find a mix that can survive the cold. Grasses such as the ryes and the fescues are good in the cold season, so they are great options for the temporary seeding.
 
Permeant seeding is to be completed when the construction activity has concluded, at least for a year or more, and so the grass species for permanent seeding can defer from temporary seeding. Per the Ohio CGP, any areas that will be dormant for over a year, or that have reached final grade, should be permanently stabilized. So, what are some of the species that can be used for this practice? Erosion from water runoff is a big issue in Ohio, and so whatever seed mixes that we choose, it should be a nice dense grass that will also promote infiltration into the ground. Table 7.10.2 of the Ohio Rainwater and Land Development Manual provides a list of mixes that are great for permanent stabilization. If nothing else, tall fescue is always a good option for permeant seed. For general use such as lawns and common areas, good options for seed mixes are as follows:

• Creeping Red Fescue, Domestic Ryegrass, Kentucky Bluegrass
• Tall Fescue
• Turf-type Fescue
• Kentucky Bluegrass with either Perennial Ryegrass or Creeping Red Fescue

The recommendations that the Ohio RLDM gives for steep slopes are very similar, there is a couple different species, however. Tall fescue is generally a very good grass to use on slopes, there are also other options that can be mixed with tall fescue. Below are recommended seed mixes for permanently stabilizing a steep slope, the exact seeding rate can be found on the Ohio RLDM:

• Tall Fescue
• Crown Vetch, Tall Fescue
• Flat Pea, Tall Fescue

Road-side ditches and swales take in a lot of water flow, and so the seed species can also be different for these waterway features. Because these areas can potentially take on a lot of water in a short amount of time, grasses that can handle the high velocities are important to have. Below are a couple of good mixes listed from the Ohio RLDM for this purpose:

• Tall Fescue
• Turf-type (dwarf) Fescue, Kentucky Bluegrass

One of the most effective BMPs that we can use on construction sites to prevent soil erosion and pollution is temporary and permanent stabilization. Putting grass seed down on exposed soil ensures that the soil is covered, and rain and flowing water cannot loosen it and sweep it away. By seeding and stabilizing exposed areas when they plan to be dormant or reach final grade, we can ensure that the soil is not running into waterways and causing further pollution to the waters of the state. Now is a great time to start planning the permanent stabilization process because the seeding window for the year opens on March 1st. Grass is one of our greatest allies in the fight against soil erosion, let’s make sure we utilize this BMP and see some green start to pop up on the exposed soils as we move into the Spring months!
 
For more information on stabilization, or any other construction site BMP, please contact our office at 513.695.1337.
 
Links:
Ohio Rainwater and Land Development Manual
Ohio Construction General Permit

Written by Seth Byerly, Urban/Ag Technician