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

Stormwater Infrastructure helps to convey rainwater, prevent flooding of homes, roadways, all while protecting water quality. Many factors can impact water quality. In this article we will look at water temperature and how stormwater infrastructure can help maintain healthy streams and lakes.
As areas become more developed there is an increase in impervious surface area. On a sunny day paved surfaces can transfer heat to the air above them and to stormwater as it flows over. The surface temperature of a parking lot can exceed 140°F on a clear summer day. This is almost hot enough to fry an egg. During a rainstorm, pavement also allows water to flow unimpeded into the storm drains. Water flowing off hot pavement becomes warmer and can cause thermal stress to organisms living in the receiving stream.

Fish and macroinvertebrates, tiny organisms which make up the base of the aquatic food chain, have a temperature range that they are well adapted to. Think of trout living in a cool mountain stream. Fish have adapted over many thousands of years to the environments in which they live. Increasing the temperature of a stream over time or subjecting the stream to sudden fluctuations in temperature will stress the fish populations in that stream. Some heat tolerant species will survive while less tolerant species will see a drop in numbers. There are many reasons for this, one of which is dissolved oxygen. Colder water can hold more oxygen which fish breath through their gills. Warmer water holds less oxygen. While our native fish populations do worse with increased stream temperatures, certain algae species can do well in warmer waters. These algae will bloom, creating additional stress on the fish since they can deplete oxygen in the water. To further complicate things, urbanization typically results in less tree canopy around streams resulting in less shade and higher water temperatures.

​Stormwater controls can help to reduce thermal stress on fish and other aquatic organisms. Grassed swales can slow down water and help it to infiltrate. Establishing clearing limits around streams helps to maintain a filter buffer or better yet, a tree canopy around the streams.
How can stormwater infrastructure help to maintain good water quality. One piece of infrastructure that can make a big difference is the basin.

In our example of hot water flowing off a parking lot, the basin slows the flow down giving the water time to cool to safer levels. Once in the basin heat transfer can occur between the water and the basin. Some transfer also takes place between the water and the air. The rate of heat loss is determined by the “specific heat” of water. The specific heat it is the amount of energy needed to change the temperature of water by 1 degree. A significant amount of energy needs removed to reduce the temperature of water. We can’t change the air temperature or how much rainfall is received.  What can be influenced is how long it takes water to flow through the basin. This is done by oversizing the basin and by installing the water quality orifice when converting the outlet structure over to post construction design. A larger basin will have more storage, increasing the water quality storage volume. The orifice plate or restriction plate is made of stainless steel and restricts the volume of water that can leave the basin in a given time. The person installing the plate should consult the Storm Water Pollution Prevention Plan (SWPPP) for which size orifice plate to install. Properly designed and maintained stormwater infrastructure helps make our rivers and streams a little cooler.

For more information, contact our office at 513.695.1337

Sediment and Erosion Control is an ongoing battle on construction sites. One day everything may be fine, silt fence is functioning, and sediment is being contained on site. But, the next day may bring inclement weather that moves sediment around and damages Best Management Practices (BMPs) for sediment and erosion control.  That’s why BMP maintenance on construction sites requires vigilance to ensure they are working to control sediment.
Recently, we got hit with a frosty snowstorm, dumping a foot of snow over Warren County. While the frozen ground may help reduce sediment runoff, there are still issues to combat. Work must continue, the roads need plowed, and sidewalks need cleared so that workers can continue to work on homes being built. So, there can be some slushy sediment that makes its way onto the streets during this time.
Dimitry Loukoumidis at Fischer Homes is well aware of the need to keep up on sediment and erosion control. Dimitri and Fischer Homes have been great to work with, consistently paying attention to site BMPs, and being communicative when Warren County SWCD site inspectors see something that needs maintenance. That’s why this month we are giving a shout-out to Fischer Homes at Losh Landing in Deerfield Township. There are always challenges with sediment for any development under construction, but Fischer Homes has been keeping up with their routine weekly street-sweeping schedule. Following this snowstorm, they are increasing their street sweeping from three days a week, to a daily basis for the sections where they are building homes. They have even coordinated with another builder in the community to coordinate their street sweeping schedules together.
 
Dimitri has provided a quote:
“One of the first things I was told at Fischer Homes was the importance of a clean and organized community. When we have potential customers driving and walking through communities, we do not want them to have to navigate mud, trash, and debris. We want them to see a well-organized community where everything has a place. We want their first impression of Fischer Homes to be positive and stand out from other builders in the area. This is especially important in communities like Losh Landing where we share the community with another builder. In order to achieve this high standard, I think that starts at the very beginning with proper sediment and erosion control. Not only does this prevent erosion from our sites and sediment getting into the roadways, it helps to protect our drainage swales, catch basins, and any surrounding properties and waterways, but it also sets clear boundaries. Whether our trade partners realize it or not, proper and consistent silt control sets clear boundaries of where they can and cannot drive, run equipment, etc. This directly impacts how much mud and debris is tracked on to the road and through the community.  In my opinion proper management of silt control and roadways are the foundation to successfully transforming a development into a community.”
 
Thank you to Fischer Homes for your hard work and here’s to a Happy New Year!

Article written by Justin Bedocs, Urban Program Specialist

The Industrial revolution saw a large amount of pollution being dumped into America’s waterways, and treatment plants were either non-existent or a far-cry compared to what they are today. The Cuyahoga River in Cleveland, Ohio was so polluted with toxic sludge that it caught fire, multiple times! The environmental revolution of the 1960s and 70s led to many environmental regulations, as people saw how poorly we were treating our environment and ecosystems. In 1948, the Federal Water Pollution Control Act became the first U.S. law to combat water pollution. This was amended in 1972 to become The Clean Water Act (CWA). The CWA has helped make the nation’s waters safer and cleaner, allowing communities to return to the water for swimming, fishing, and recreation. Environmental laws like the Clean Water Act aren’t going away. They are still needed to continue protecting America’s cherished natural resources for future generations.
The Clean Water Act established the National Pollutant Discharge Elimination System (NPDES). There are a multitude of pollutants that enter America’s waterways, so there are a multitude of permits regulating discharge to those waterways. The NPDES permit we will focus on today, is the Construction Stormwater General Permit (CSGP). This permit allows discharge of stormwater from construction sites, provided that certain treatment practices are installed during construction.

Why is Dirt so Dirty?
Sediment is the largest pollutant in Ohio’s lakes and streams, so the CSGP aims to reduce the amount of sediment-laden water being discharged from construction sites. Excessive sediment in waterways can cause fish kills and disrupt ecosystems. It clouds the water column and makes it hard for aquatic life to breathe and find food. Fertilizers, pesticides, herbicides, and other pollutants also bond with sediment. It turns out that Ma was right all along. Dirt is dirty. So, take your shoes off at the door!

When is the Permit Required?
We are currently in the sixth generation of the CSGP. This Ohio EPA permit (OHC000006) is required for any project that will disturb one or more acres of earth. It is required to discharge stormwater from the construction site when the ground is exposed to the elements and erosion occurs. More information regarding this permit can be found here.
To obtain coverage, the applicant must submit a Notice of Intent (NOI) to the Ohio EPA. Once this permit is received from the EPA, a Stormwater Pollution Prevention Plan and Earth Disturbing Permit (EDP) Application must be submitted to our office for review to ensure sediment and erosion control measures will be installed throughout the project. The EDP application can be found and submitted here. Our urban technicians inspect the site each month to make sure the permit requirements like sediment and erosion control measures are being upheld. When the project is complete and the site is stabilized, a Notice of Termination (NOT) must be filed to close out the permit coverage. These applications can be found in the Ohio EPA eBusiness Center Surface Water Tracking, Reporting, and Electronic Application Management System (STREAMS) here.

Who Is Responsible for Sediment and Erosion Controls?
The contact listed on the CSGP Notice of Intent (NOI) application or the designated SWPPP contact is responsible for upholding permit requirements and maintaining sediment and erosion control measures throughout the duration of the project. Sometimes it’s a building company that does the total site development and the construction. In other cases, there may be a developer who only does the grading, roads, and utilities, but then a builder comes in for the construction later. In this case, the permit coverage needs to be transferred to the builder(s). If there are multiple builders, each builder would need to sign up as a co-permittee to the overall site permit. That way, each builder is aware of their responsibility for individual lot controls to keep sediment contained.
In a situation where each house is a separate builder, and disturbance is less than one acre, the permit is still needed. Ohio EPA refers to this type of project as a Common Plan of Development (as defined in Appendix A of the CGP). This occurs when there is a contiguous area where multiple separate and distinct construction activities may be taking place at different times on different schedules under one common plan. There are two ways permit coverage can be transferred, Co-Permittee coverage and Individual lot coverage.
 
Co-Permittee Coverage
Co-permittees can be added to a permit if there are multiple developers or contractors working on a project that falls under one general permit and there are centralized sediment and erosion controls (controls that address runoff from one or more lots, I.e., a basin or ditches/inlets along roadways not associated with a specific developed lot). A common example of this is a large residential subdivision development with centralized storm control features that has different builders working on different sections/lots throughout the development. Without obtaining the co-permittee coverage for those different contractors, the original overall development permittee (typically developer/SWPPP contact) retains the responsibility of both the centralized sediment and erosion control measures and the individual lot controls. Therefore, adding those entities as co-permittees to the project transfers responsibility of individual lot controls maintenance to the builders/contractors and the developer retains responsibility of the centralized features.

Individual Lot Coverage
If there are no centralized storm control features and the transfer of permit coverage will not prevent or impair the implementation of controls, the original permittee can transfer responsibility to individual lot owners. In this case, the original permittee must temporarily stabilize sold lots, inform the new lot owner of his permit obligations, and ensure that an Individual Lot NOI application is submitted to the Ohio EPA at least seven (7) days prior to the date the new lot owner intends to accept permit responsibility.
 
In both the case of adding co-permittees and obtaining individual lot permit coverage, the lot owner should obtain a copy of the original SWPPP and comply with its requirements. Depending on site topography and location, additional controls above and beyond those outlined for the "typical" lot may be required. The new lot owner may also be partially or completely responsible for amending the SWPPP and installing those controls.

For more information please contact Warren SWCD at 513.695.1337

Winter is officially here! Well, not officially, but the time to stabilize construction sites for the winter is here!  The winter stabilization window listed in the Rainwater and Land Development window is November 1st through February 29th. Any areas that have exposed soil on an active construction site will need to be stabilized for the winter if the area will be dormant for 21 days or more over the winter. This month’s development digest on winter stabilization is a basic overview on why this BMP (Best Management Practice) is important, and the specifications of this stabilization practice.
Soil pollution is an issue that greatly affects the water that runs through Warren County. Soil pollution can be greatly increased in the winter due to the large amounts of snow, and melting of that snow, that creates water runoff. BMPs are practices we can put in place to minimize the risk of soil pollution. Winter stabilization is an important BMP that can help keep the soil out of the waters.

So, what exactly does winter stabilization entail? Winter stabilization can involve two different methods. The first method involves planting a dormant, cool season grass that will survive the winter and start its growth in the spring. Putting mulch down is also a necessary step to allow this method to be effective. The second method is to only put mulch down and not worry about the seed. This method may be more applicable if earthwork will resume directly at the end of winter when work starts back up. Both methods involve mulch, which is important because mulch provides a barrier between the stormwater and the exposed soil that help to keep the soil in place. Below are examples of types of mulch and types of grass seed that can be used.
 

Types of Mulch:        

• Straw                                                                                                
• Straw matting
• Wood chips
• Shredded woody material
• Pine needles
• Compost

 
Grass Species:

• Tall fescue
• Annual Ryegrass
• Perennial Ryegrass
• Kentucky Bluegrass

 
 
More information on temporary seeding throughout the year can be found on Table 7.8.1 of the Rainwater and Land Development Manual. For an area to be considered stable, 70% of the area should be seeded and mulched.
Stabilizing a site during the winter is the best method to prevent erosion and sediment runoff during a time of the year when work may not be happening. At the very least, dormant areas with exposed sediment should be mulched during the winter months. Further information on temporary stabilization techniques can be found on the Rainwater and Land Development Manual. Further information on stabilization regulations can be found in the Ohio Construction General Permit.
​
Have questions on the topic of winter stabilization? Please feel free to reach out to our office through email at [email protected] or call us at (513) 695-1337.  

As cooler weather moves in, I hope you find time to kick back with a warm cup of your beverage of choice and this article considering Settling Time. For this article we will talk about different factors which impact how long it takes for particulates to settle out of stormwater once in the retention basin.

Stormwater retention basins are features that help to do the following:
*  Hold back water to help mitigate downstream flooding.
*  Settle out particulates to improve downstream water quality.
*  Slow down the rate of stormwater flow to help control erosion.
​*  Lower the temperature of the stormwater before it can flow downstream.​

As storm water flows over construction sites, parking lots and roads it picks up dirt and other debris that make up the suspended solids. The suspended solids can be sand, clay, silt and other particulates. The sediment load will vary based on the amount and duration of the rain event. Once the stormwater reaches the basin its flowrate drops off. In a quiescent pool the solids carried by the stormwater are given time to settle. If there is still flow through the pool or a second rain event occurs particulates may not have time to completely settle. These flow conditions would result in dynamic settling or possibly resuspension of sediment. Some particles are so small they will not settle. Others will have a settling time that is based on their particle size, shape, density and the water temperature. Solid settling in a stormwater basin can be estimated by Stokes’ Law.

Where:
V = settling velocity of the solid
g = acceleration of gravity (constant)
p1= mass density of the solid
p = mass density of water (constant)
d = diameter of the solid (assuming spherical shape)
µ= kinematic viscosity of water (varies only with temperature).

From the above equation we can see that particulates of higher mass density (p1) will settle out a bit more quickly than particles with lower mass density. (p1) We can also see that larger diameter (d2) particulates will settle out much faster than smaller particles. As diameter increases the settling velocity increases exponentially. Suspended solids vary in size with a particle of coarse sand being about 1,000x larger than a particle of fine clay. Given the larger diameter of the sand particles, we would expect them to settle much more rapidly than clay. Lastly temperature comes into play. Water becomes more viscous (µ) as temperature decreases. This higher viscosity leads to slower settling times.

Other factors come into play when considering settling time. Though the Stokes equation assumes that particles are round, few particles would be perfectly spherical. The irregular shaped particles would likely settle more slowly. Concentration of particles also plays a role. Like snowflakes falling from the sky, sediment particles can collide forming larger floc particles. These floc particles will settle more rapidly. In fact, flocculant is sometimes used to bond to suspended sediment or chemicals to sink them to the bottom and reduce the amount of polluted water leaving the basin. Chemical properties will also play a role. An extreme being road salt. The salt mineral is dense and of large diameter but will dissolve into the water. 

The dissolved road salt will not settle out of the stormwater. Particles with a greater attraction to water will settle out more slowly or will remain in solution.
A well designed and maintained basin will slow water and hold it long enough to allow sediment to drop out of solution. Oversizing a basin is one way to ensure plenty of settling time. Depth of the basin also comes into play by providing a large enough sediment storage zone. Maximizing the distance between the inflow and outflow helps maximize detention time. The challenge is designing a basin that will provide time for solids to settle, store sediment, minimize the valuable real estate it will take up and provide for easy maintenance down the road. 
​
For more information contact our office at 513.695.1337

​You may have heard lately that Ohio is in a drought. A recently released drought map indicates Warren County to be in a severe to extreme drought. During these dry times, your construction site may welcome the lack of rain as dry sites can be easier to move around on and experience fewer issues with sediment and erosion control. However, we can’t get complacent on sediment and erosion control. The battle must go on!

In this month’s Development Digest, we will discuss remaining vigilant during dry times by having a routine dust control program in place, as well as making sure site BMPs are ready to go for the big rain. Dust can be a real problem during times of drought. So much so, that Soil and Water Conservation Districts were established to combat this issue, after the Great Dust Bowl of the 1930s. Poor farming practices, dry conditions, high winds, and plowing all combined to stir up the earth and create massive dust storms throughout the Midwest. President FDR signed the Soil Conservation Act of 1935 to protect our Country’s soil and water resources. This led to the establishment of the Ohio Soil and Water Conservation Commission (OSWCC) in 1941, which allowed funding to create Soil and Water Conservation Districts throughout the state. On construction sites, we often focus on keeping sediment contained during rain events, but soil loss can also occur during a drought. That’s why it’s important establish a dust control routine to keep sediment contained. Dust can be a real problem, as it is considered an airborne contaminant. Nearby existing homes and property can be covered in dust. It can become a public health concern when residents have trouble breathing. Our office has been receiving complaints from many sites throughout the county and we have been working with site contractors to ensure dust control measures are being enacted. 
​
This can become a sleeping monster if dust control isn’t implemented. During times of extended drought, the ground becomes drier and harder. Especially in Warren County where much of the soil is clay, the ground can become like an impervious surface when it is compacted, dried and hardened. So, when it does eventually rain, the first initial downpour will likely run off the surface quickly, like it would on pavement. To further compound the issue, vehicles driving around on the site stirs up the sediment, creating dust clouds that will settle on the hard ground.  This fine-grained dust that settles accumulates almost like the regolith and dust on the surface of the moon. We are seeing anywhere from 1 to 3 inches of dust settled on some sites lately. 

4. Stone- Install crushed stone on graded roadways with construction traffic.
5. Barriers- Snow fencing or other suitable barriers may be placed perpendicular to wind currents to control air currents and blowing soil.
6. Calcium Chloride- the chemical may be applied by mechanical spreader as loose, dry granules. Follow manufacturer’s specs.
7. Operation and Maintenance- Repetitive, routine treatment of dust control practices.
8. Street Cleaning- Remove any settled dust from paved areas with a routine street sweeping schedule.

​Due to the recent drought, this is a great time to think about dust control. It looks like we will be getting some rain soon, so keep these practices in mind for the next dry time! If you have any questions regarding dust control you can contact us at the Warren County Soil and Water Conservation District website https://www.warrenswcd.com/ or by our phone number at (513) 695-1337.    

Additional Resources
 
Ohio EPA Rainwater and Land Development Manual. Chapter 7 Soil Stabilization – Dust Control: https://epa.ohio.gov/divisions-and-offices/surface-water/guides-manuals/rainwater-and-land-development?msclkid=cb5f60f4b48d11ec8b5ece1ef5e16d3c

In this month’s development digest, we will learn about storm drain tags, and how developers in Warren County can easily add them into their construction process to protect the natural waters. Storm drain tags are an important tool that we can use to keep pollutants out of the natural waters, and so this article will go into what a storm drain tag is, different types of tags, and why it is worth the extra little bit of effort to install these tags.
What is a storm drain tag?

• A storm drain tag is a type of label placed on a storm drain to prevent anyone from dumping harmful pollutants into the drain.
• The main purpose of the label is to provide a visual warning to keep people from illegally dumping into the drain, and to also provide education to those who may not know about the pollutants that can’t be dumped into the drain.

 
Why might a developer want to spend money on storm drain tags?

• Storm drain tags are an inexpensive way to promote a healthier and more environmentally conscious community.
• They can protect the integrity of storm drains.
• Ensuring that only rain goes down the drain will help keep retention basins clear and attractive. Reduces the need to use excess pond dye since the water is already healthy and clear.
• Can save money in the future by preventing spills of hazardous material that requires clean-up.

 
Types of Drain Tags

• There are a few main types of drain tags: Pre-cast, plastic, and metal tags.
  • Pre-cast: Pre-cast storm drain tags are casted onto the storm drain when the structure is built. Pre-cast tags require the least effort since they are made with the rest of the storm drain.
  • Plastic: Plastic storm drain tags are typically attached to the drain using glue. A substantial amount of glue should be used to install the tags to create a proper seal.
  • Metal: Metal storm drain tags can be installed either with glue like the plastic, or some tags have a bolt and a nut that holds the tag in the grate of the storm drain.
  • All three of these tags are effective methods to keep pollution from entering the drains.

 
If you have any questions regarding storm drain tags or the installation of the tags you can contact us at the Warren County Soil and Water Conservation District website https://www.warrenswcd.com/ or by our phone number at (513) 695-1337.
 
 
Additional Resources
Nonpoint Source Pollution – US EPA

​Sediment basins are designed to trap sediment from a construction site. If not maintained properly the basin can become filled with sediment and algae. While keeping sediment and algae out of the basin may seem like an impossible task, there are steps that can lessen the buildup and costly maintenance associated with dipping out or treating the basin. The following article covers sediment basin function, maintenance, and considerations to reduce algae.
Sediment Basin Basics
A sediment basin is a settling pond. By slowing down the flow of sediment-laden runoff, solids can settle out and sink to the bottom of the basin. The sediment basin is constructed as a first step, prior to land disturbing activities. The settling basin is usually converted to a wet retention basin or a dry detention basin at the end of the construction project. During construction, the basin functions for sediment control while after construction, the basin functions for stormwater flood control and water quality improvement practice.
How it Works 
As construction site runoff flows into the basin its flow rate is slowed on reaching the basin. Heavier sediment particles sink to the bottom while clean water remains in the top dewatering zone. As the water makes its way to the outlet a skimmer pulls water from near the surface and directs it through the principal spillway. During extreme rain events water would build up in the basin then flow through the riser and the principal spillway.

Maintenance for Proper Function and Control of Algae
For a basin to function, accumulated sediment must be removed from the sediment storage zone once it exceeds 50 percent of the minimum required sediment storage design capacity and prior to the conversion to the post-construction practice. Excess sediment in the basin decreases the depth of the dewatering zone, brings in other potential pollutants, such as nutrients. Sediment buildup also increases the maintenance required to keep the basin functional.  
The shallow water also allows additional sunlight to make its way to the bottom of the basin further warming the water. Shallow water promotes the growth of vegetation, algae, and mosquitos. Algae can increase maintenance needs by creating additional solids that settle to the basin bottom and fill the sediment storage zone with muck. Some blue green algae can also produce toxins making the water unsafe.
​
Prevent Early Fill-up of the Sediment Storage Zone
The following steps can help minimize maintenance needs while keeping the basin functional.

1. Stabilize the inner bank of the basin as early as possible utilizing grass seed and straw matting.
2. Remove sediment from inflow into the basin by utilizing stabilized grass swales, silt fence, or filter sock and other best management practices on the construction site.
3. Excavate the construction site in phases so that less of the dirt is exposed and subject to erosion.
4. Keep the disturbed area of the site as small as possible.
5. Stabilize the construction site as soon as possible.
6. Have a pond management company treat algae blooms before they become severe.
7. Dip sediment once it exceeds (50%) of the minimum required sediment storage and prior to conversion to post-construction.

Prevention of excess sediment in the basin is often more cost effective than bringing in heavy equipment to dip out the basin and then hauling off the sediment. These steps can also reduce resident and local homeowner association complaints down the road.
 
Additional information can be found in the Rainwater and Land Development Manual, Chapter 6

​Questions? Contact our office at 513.695.1337

​In an episode of Seinfeld, Newman is quoted as saying “The mail, it never stops Jerry!” The same can be said for maintenance of sediment & erosion control measures (SECMs) on construction sites; it is a never-ending battle, and it never stops!
 
Your project should have a stormwater team established to ensure that all SECMs are inspected once every 7 calendar days and after every > 0.5-inch rain event per 24-hour period by the end of the next calendar day (per Ohio EPA Construction General Permit requirements). The stormwater and resulting sediment-laden runoff, never stop. So that’s why it’s important that we remain vigilant and maintain the SECMs until the site is stabilized with grass.
 
Warren County SWCD conducts monthly site inspections to help your crew identify failing or missing BMPs to help you stay compliant with the Construction General Permit. When we encounter a project that has done a great job on installation and maintenance of the SECMs, we like to highlight it in our Development Digest for a job well done.
 
This month, we call attention to the Eastern Gas Transmission and Storage, Inc. (EGTS) Lebanon Compressor Station HP project in Clearcreek Township. EGTS boasts a robust environmental compliance division as well as an on-site stormwater team that has been great to work with. The stormwater team has followed the Stormwater Pollution Prevention Plan (SWPPP) to make sure the SECMs are properly installed and maintained.
 
Not only does the site exemplify superb examples of proper SECM installation, maintenance, and an inspection routine, but they also place an emphasis on employee safety. The focus on safety really demonstrates how it’s not just about protecting the environment, but also the people that work together to achieve a common goal.
 
The site is not without its challenges however, with a wetland conveniently nestled between construction areas. The stormwater team has highlighted the importance of protecting the wetland to prevent sediment from filling it in. Most of Ohio’s wetlands have been lost since the days when Ohio was a frontier state. EGTS understands the importance of protecting the ones we still have left. But don’t take my word for it! Hear it from the pros at EGTS:

​In closing, we at Warren County SWCD understand that development does not come without risks to the environment, that’s why it’s important that development happens in an environmentally conscious way. So, well done EGTS. May all other construction sites follow your lead!

​​Questions about BMPs?  Call Warren Co SWCD offices at (513) 695-1337