Why is Sediment Considered a Pollutant? We know what you’re thinking… if sediment is a naturally occurring resource found all over the planet, why is it considered a stormwater pollutant? Let’s dig into how sediment erosion affects the health of our lakes, streams, and rivers. Sediment erosion by water is a natural process which shapes the world as we know it. Take the Grand Canyon for example- a natural wonder of the world formed by erosion over millions of years! The key is slow change over a very long period. Human activities that result in large swaths of unstabilized soil (urban development, agriculture, forestry, etc.) accelerate erosion and dump large amounts of sediment into nearby watercourses. According to the United States Environmental Protection Agency (USEPA), “natural erosion produces nearly 30 percent of the total sediment in the United States, accelerated erosion from human use of land accounts for the remaining 70 percent.” While an appropriate amount of suspended and bedded sediments (SABS) is essential to the physical, chemical, and biological integrity of an aquatic ecosystem, an imbalance of SABS can cause serious problems. Too much sediment in the water column can result in death of aquatic life and reduced navigability/recreational enjoyment for humans. Even worse, filtration of drinking water becomes more challenging and therefore more expensive. Imbalanced sediment supply is a leading cause of waterbody impairment in the United States.
How does too much sediment harm water quality and aquatic life? Aquatic organisms that hunt and/or find food using eyesight will be disadvantaged by the cloudy water. Submerged aquatic plants will receive less sunlight, photosynthesize less, and therefore produce less oxygen. Even if there was enough biologically available oxygen for the fish to breathe, they will struggle to do so with clogged gills. Sediment particles will fill crevices in the stream bank which reduces habitat availability. In addition to physically muddying up the water, soil particles introduce toxic pollutants to the watercourse which they bonded with in the landscape (fertilizers, heavy metals, bacteria, pathogens, etc.) Sediment pollution is an interesting topic with several consequences beyond clogging up storm drains. Check out the additional resources below to learn more about how sediment pollution affects our waterways and how you can stay in compliance. Additional Resources USEPA Sediments Overview Ohio Rainwater and Land Development Manual Ohio EPA NPDES General Construction Permit (OHC000006)
0 Comments
I’m just clearing. Do I need a permit? The answer is likely yes! In Warren County, an Earth Disturbing Permit (EDP) is required for any project expected to disturb a total area of an acre or more of land. Removing trees with the entire root ball results in land disturbance and exposed soil. Clearing involves the cutting and removal of trees, brush, and other above ground material while grubbing is the removal of roots, stumps, and other material below the existing grade. Regarding an EDP, it does not matter whether the vegetation was naturally occurring or intentionally planted. If you think of this in terms of one tree, it might not seem like a huge concern, but when you think of this type of tree clearing on a large scale (i.e. an acre or more of tree clearing), it can lead to quite a bit of disturbed soil and potential for sediment-laden discharges from the site during rainfall events. Are there any other restrictions for clearing? Yes, depending on when and where you are developing. Tree clearing must not occur between April 1st and September 30th without first coordinating with the Ohio Department of Natural Resources- Division of Wildlife (ODNR-DOW) and the U.S. Fish and Wildlife Service- Ohio Field Office (USFWS-OHFO). Native bat species roost and raise their young in trees all throughout Ohio during this time each year. Unfortunately, all bats in the state are experiencing population decline and have become protected by law in some way. The U.S. Endangered Species Act of 1973 is periodically updated to protect endangered and threatened flora and fauna across the country. Federally endangered species in Ohio include the Indiana Bat (Myotis sodalist) and Northern Long-Eared Bat (Myotis septentrionalis). If your project calls for tree-clearing activities during this five-month window, the ODNR and USFWS will recommend surveys be conducted to determine if the proposed area will negatively impact the bats. If there are no hibernaculum or bats identified during the survey, it may be safe to proceed with tree clearing. Photo credit: Ann Froschauer, USFWS For earth disturbing activities immediately adjacent to surface waters of the state, the Ohio Environmental Protection Agency (OEPA) requires that, if feasible, a 50-foot buffer on either side of the ordinary high-water mark must remain undisturbed. Trees and brush along a water bodies’ edge provides significant stream bank stabilization. If a natural buffer cannot be maintained, land must be temporarily stabilized within two days of the most recent disturbance (if the area will remain idle for more than 14 days) and permanently stabilized within two days of reaching final grade.
Whenever possible, we strongly recommend preserving trees during land development as they prevent erosion, reduce runoff rates, and increase property value. For guidance on tree and natural area preservation, refer to Chapter 7.3 of the Ohio Rainwater and Land Development Manual. Additional Resources USEPA Preserving Natural or Existing Vegetation Fact Sheet Ohio Rainwater and Land Development Manual Ohio EPA NPDES General Construction Permit (OHC000006) BMP Blasts are issued every three months to highlight a sediment and erosion control best management practice. These blasts are designed to provide helpful insight and tips for properly designing, installing, using, and maintaining the control measure. Where and why is inlet protection required? Inlet protection is required on any storm drain at risk of receiving construction site run off. That said, there are limitations to the power of inlet protection. These controls are only designed to manage sediment from a drainage area of one acre or less. If greater than 1 acre of land is draining to one inlet, additional practices such as sediment traps or basins may be required. You may be thinking, “but, I have silt fence and a basin with a skimmer already!” Unfortunately, no one practice is 100% effective when it comes to sediment removal; they each have different strengths and weaknesses. For example, inlet protection has a limited ability to remove silts and clays but can effectively capture larger sand-size particles. The combined effect of each BMP helps to provide maximum sediment removal from storm flows prior to off-site discharge. In other words- perimeter controls, inlet protection, and a basin with a skimmer are likely all required (depending on the site and area of disturbance). Should I have inlet protection listed on my SWPPP? Yes! Inlet protection must be shown on the stormwater pollution prevention plan. While most contractors are familiar with the need for inlet protection, it is important that this is noted on plans to ensure any operator on-site is aware of the requirements and a proper maintenance schedule can be in place. The plan will also show the location all of these “at-risk” inlets so that protection gets installed on all drains and inspectors on-site can identify the location of these areas. Furthermore, it is important to show where these practices will be located in the plan review process to ensure that the drainage area is sized appropriately for the practice. There are certain considerations for placement as well. For example, practices that operate by blocking water from entering storm drains almost completely prevents sediment-laden discharges to entering the conveyance system, but they often result in ponding water. This ponding may be important to consider if these practices will be used on roadways that could flood during heavy rainfall. Are there different types of inlet protection? There are various methods of inlet protection specified in Chapter 6 of the Ohio Rainwater and Land Development Manual. Each method utilizes a combination of stone, wire mesh, and/or geotextile to filter sediment. Alternatively, pre-manufactured inlet protection devices may be used (and reused for the lifetime of the product). What kind of maintenance do inlet filters require?
Additional Resources OEPA Rainwater and Land Development Manual United States EPA Storm Drain Inlet Protection Fact Sheet Ohio EPA NPDES General Construction Permit (OHC000006) Fall-time in southwestern Ohio is simply wonderful; the weather starts to cool down and the trees transform into a lovely autumn palette. Around this time of year, we like to remind developers to continue seeding as much bare soil as possible before winter turns the corner. Soil erosion remains an area of concern for earth disturbing work throughout winter as melting snowfall transports sediment into our local waterways. According to the Ohio Rainwater and Land Development Manual, soil stabilization is the most effective way to minimize sediment erosion from construction sites (over >90%). We mean it when we say seeding and sod installation is music to our ears! Temporary seeding (which must be applied to bare soil where additional work is not scheduled for more than 14 days) may continue until November 1st. Especially through late fall, we recommend monitoring and maintaining seeding efforts until an overall vegetative density of >70% has been achieved. Fall-time seeding species include Rye, Tall Fescue, Annual and Perennial Ryegrass, Creeping Red Fescue, and Kentucky Bluegrass. A layer of mulch (straw, wood cellulose fiber, and/or mulch matting) must be applied during or immediately after seeding. During more favorable seeding times of year, mulching may not be necessary but late fall weather warrants the extra protection. The window for permanent seeding (which must be applied to bare soil at final grade that may be idle for over 1 year) has now closed (March 1st through September 30th). Click here for our guide to dormant seeding during winter months. Traditional permanent seeding efforts may germinate during late fall, but they are unlikely to survive the winter. Spotlight Example from the Field: Seeding Before Winter Ryan Wilms and his team at Cincinnati United Contractors have been working on improvements at Green Bay Packaging in Lebanon, OH. During routine inspections, we noticed their team’s excellent pre-winter stabilization. Having this steep slope stabilized now will set them up for success throughout winter. This also allows for more efficient sediment management throughout the rest of their project. What if temporary/final grading work took longer than expected and you missed the seeding window? Although the disturbed areas cannot be traditionally seeded after the windows have closed, bare soils must be mulched or dormant seeded. For more specific technical guidance and specifications, please review the most recent OEPA Construction General Permit (OHC000006), the Rainwater and Land Development Manual, and the Stormwater Pollution Prevention Plan (SWPPP) for your site. Additional Resources Construction Site Winterization – Development Digest Rainwater and Land Development Manual Ohio EPA NPDES General Construction Permit (OHC000006) Seeding Tables – USDA NRCS Sediment and erosion control maintenance needs are inevitable on construction sites. With the nature of construction activity and rainfall events, it is nearly impossible for controls to stay in perfect condition throughout the entire process. However, the more that your team stays on top of maintenance needs and acts proactively, the better the chances are to keep controls functioning and keep your site in compliance. General BMP Inspection Tips: The best way to stay on top of maintenance needs is to conduct routine inspections according to the guidance provided in the Rainwater and Land Development manual. Controls should be inspected daily for general condition and effectiveness. They should also be inspected after each rainfall event and during a prolonged rainfall. If controls aren’t being inspected on a regular basis, it is easy for small maintenance needs to compound and become larger issues over time. Below are 7 common BMP maintenance needs our urban inspectors see out on site and some tips for staying on top:
Fix Tips: If silt fence is downed, it may be able to be retrenched and wrapped around the stakes again. Ensure silt fence is properly trenched and pulled taught. If the geotextile material has been damaged, it will need replaced entirely. 2. Inlet Protection or Curb Stop Damaged Fix Tips: If using a basket or dam style inlet protection, ensure that capture device is secured underneath grate to prevent getting pulled into catch basin or swept into roadway. For curb inlets, ensure that curb stops are installed along rear of the grate to ensure that water cannot enter through the sides or top of the inlet. 3. Compost Filter Socks Flattened / Moved Fix Tips: Replace socks that have been torn or damaged beyond repair. If socks have just become flattened, refill with compost material until they are returned to the appropriate diameter. Encourage your team to use established construction entrances to prevent running over the socks. If the socks are moved for utility or other work on the lot, ensure that they are replaced in the appropriate location as soon as feasible. 4. Sediment Build Up in Street Fix Tips: Sweep the streets any time you notice a significant amount of tracking occurring. Establish a routine street sweeping schedule to prevent heavy accumulation on roadway. Ensure other practices (such as silt fence or filter socks, proper construction entrances) are in place and functioning to help stop sediment tracking in the first place. 5. Compost Filter Berms Blown Out Fix Tips: If you notice sediment is overtopping the berms, the sediment may need to be dug out away from the berm area. It’s best practice to keep the sediment deposit level below ½ of the height of mulch berms or silt fence. If a heavy rainfall knocks down a portion of the berm, make sure that berms are built back up to meet the specifications outlined in the RWLD manual. 6. Maintain Construction Entrance Fix Tips: ODOT 1/2s should be used for construction entrances. Smaller gravel tends to get swept into the roadway with sediment. If the incorrect aggregate is used, this will need to be revised to prevent off site tracking. If a construction entrance is regularly used, the aggregate may need to be replaced to provide ample area to kick sediment off wheels. 7. Concrete Washout Area Full / Needs Cleaned Up Fix Tips: Concrete washout pits should be emptied on a regular basis to prevent overflowing. If pits are dug out in the ground, they should be lined with a tarp to prevent leaching into bare soils. If the liner gets damaged or rolled up, it needs to be readjusted or replaced. The pit should have four walls around (typically lined straw bales). If the walls of the pit are compromised, they need to be rebuilt or replaced. BMP Spotlight Example from the Field: |
BMP SPOTLIGHT: Rain Garden, Warren County Soil & Water Conservation District If you have ever visited our office in Lebanon, you may have noticed this little garden next to our parking lot. What you may not have noticed is that it is a garden is designed with stormwater management in mind. It helps collect and clean water runoff from our parking lot. Feel free to stop by if you’re in the area and take a look at green infrastructure and low impact development in action! |
Other examples of Green Infrastructure that can be used as part of a Low Impact Development plan can be found here: https://www.epa.gov/green-infrastructure/what-green-infrastructure
Additional Resources
www.warrenswcd.com/rain-gardens.html
https://www.epa.gov/nps/urban-runoff-low-impact-development
http://www.wceo.us/
Additional Resources
www.warrenswcd.com/rain-gardens.html
https://www.epa.gov/nps/urban-runoff-low-impact-development
http://www.wceo.us/
One of the requirements for stormwater pollution prevention plans (SWPPPs) is to include an implementation schedule for major construction operations. This includes things like clearing, grubbing, excavating, grading, utility installation, and other similar activities.
The Ohio EPA Rainwater and Land Development manual includes a table of what this general sequence should look like: https://epa.ohio.gov/static/Portals/35/storm/technical_assistance/6-24-09RLDCh8.pdf (pg 13)
There are steps that should be taken as early in the construction process as possible to avoid problems with sediment and erosion control later in the project.
The Ohio EPA Rainwater and Land Development manual includes a table of what this general sequence should look like: https://epa.ohio.gov/static/Portals/35/storm/technical_assistance/6-24-09RLDCh8.pdf (pg 13)
There are steps that should be taken as early in the construction process as possible to avoid problems with sediment and erosion control later in the project.
Let’s breakdown those crucial early steps:
- Protect your natural areas. As construction activity is commencing, everyone working on the site should be aware of protected forested areas, streams, and wetlands that should not be disturbed. These should be marked off with easily identifiable fencing. If areas that were meant to be left alone get impacted, it can cause harm to sensitive natural areas and may also be in violation of other state and federal permits.
- Construct an area where equipment and vehicles have a clean exit from the site. A proper construction entrance/exit should consist of ODOT #1/#2's aggregate over a geotextile base. The proper aggregate size helps to ensure there will be enough vibration under the tires to kick mud off equipment and vehicles before leaving the construction site. It is best to have this installed as soon equipment and trucks are moving on and off the site to prevent off-site tracking.
- Install perimeter controls around all areas planned for disturbance. Clearing trees (root ball and all), grubbing, and grading work results in exposed soils. That sediment must be contained on the construction site. Perimeter controls need to be up around the entire perimeter of disturbance to help intercept sediment-laden discharges from moving off-site during rain events.
- Construct temporary basins. Basin construction should be part of the initial phase of construction. Basins must be installed and functional before any upslope development. As soon as the basin is dug, apply temporary seeding treatment to ensure embankments are stabilized throughout construction. Doing this early in the process helps to prevent erosion in the basin and sediment storage problems. The basin outlet structure should also have a skimmer device installed as soon as possible for de-watering off the surface of the basin rather than lower depths of water where more sediment is present.
- Follow construction timeline for remaining controls. Other sediment and erosion controls should also be installed as soon as possible. For example, when streets are installed, a sweeping schedule should be established. As new catch basins or street inlets are installed, get inlet protection on them right away. As lot development begins, make sure individual lot controls are in place. When concrete pouring is in full swing, there should be a designated washout area with controls.
- Communicate with your SWPPP inspector! Keep your inspector in the loop when new phases of the project begin in between inspection periods. If there are changes to the timeline or problems with getting certain controls established, let your inspector know so that they can help provide guidance that can help to keep things on track.
Generally, the sooner these controls are implemented, the better the outcome for sediment and erosion management. It’s always better to work proactively rather than to have to fix problems that arise from waiting too long to implement or correct controls.
Phased Disturbance is another tool to keep in mind when developing SWPPPs and generating a construction sequence. This practice minimizes the amount of grading done at one time. Planning smaller earth moving efforts allows for parts of the site to remain undisturbed and stabilized while other parts are being actively worked. Planning disturbance in this way helps reduce the amount of sediment that controls manage at one time, which increases the effectiveness of these practices.
BMP Spotlight Example from the Field: Early Construction Process Communication and Implementation
Monarch Homes and Diggit Excavating met with Warren Co SWCD at a pre-construction meeting with the City of Lebanon where the requirements and sequence of sediment and erosion controls measures were discussed. Since that meeting, the team has been in constant contact with Warren Co SWCD, proving updates on initial groundbreaking and the control installation timelineas well as any changes to controls being used on the construction site.
As soon as clearing and grading work was set to begin, there was a proper construction entrance in place and silt fence around the clearing boundaries that was supplemented with a mulch berm from the on-site clearing. The basin was dug as part of the first phase as well. The basin will be temporarily stabilized and have a skimmer installed on the outlet once installed.
We asked our friends at Diggit Excavating for their take on how communication has helped with the development process from their perspective:
As soon as clearing and grading work was set to begin, there was a proper construction entrance in place and silt fence around the clearing boundaries that was supplemented with a mulch berm from the on-site clearing. The basin was dug as part of the first phase as well. The basin will be temporarily stabilized and have a skimmer installed on the outlet once installed.
We asked our friends at Diggit Excavating for their take on how communication has helped with the development process from their perspective:
“At Diggit Excavating we strive to minimize the impact our work has on the surrounding environment. The relationship between community, agency, and contractor is something we take seriously and work hard to cultivate and maintain. Everything as designed on paper is not always perfect in the field but, with proper communication, we can work through any situation to develop practical and real work solutions that help maintain environmental controls. One way we like to accomplish this is by meeting with the agency up front to discuss the project and its environmental requirements to identify specific site constraints and other potential issues before they arise. Warren County has always been very accommodating and great to work with in this regard. Both parties appreciate and encourage this kind of involvement.” |
This is a great example of communication between our agency and developers and contractors on projects and how compliance can begin right out of the gate as a new project begins. This proactive approach helps to avoid many complications later in the construction process.
As it can sometimes be difficult to translate technical regulations into feasible solutions in the “real world” on-site, we decided to spotlight some practices with examples we've found while conducting our inspections.
This month we noticed some great Best Management Practices in Hamilton Township on the Valley View Subdivision site. Everyone that enters the site is greeted by a large-format blue sign at the main construction entrance outlining site safety and erosion control rules, so it's easy for everyone to reference at a moment's notice. There is also a great example of a SWPPP storage box containing the SWPPP and keeping it accessible while safe from the elements. Aaron Smith with DR Horton provided some insight into how the stormwater team approaches stormwater runoff on the construction site:
This month we noticed some great Best Management Practices in Hamilton Township on the Valley View Subdivision site. Everyone that enters the site is greeted by a large-format blue sign at the main construction entrance outlining site safety and erosion control rules, so it's easy for everyone to reference at a moment's notice. There is also a great example of a SWPPP storage box containing the SWPPP and keeping it accessible while safe from the elements. Aaron Smith with DR Horton provided some insight into how the stormwater team approaches stormwater runoff on the construction site:
“D.R. Horton is strongly committed to protecting the environment in every community in which we construct and sell homes. Each employee has an obligation to act, and to ensure that our subcontractors act, in an environmentally responsible manner. The Valley View subdivision has been a prime example of the effectiveness of this strategy which cannot be successfully implemented without the division stormwater compliance representative, site stormwater compliance representatives, and our trade partners and vendors working together to achieve compliance with environmental rules and regulations.
We at D.R. Horton greatly appreciate the recognition of our stormwater program and it cannot work without our on-site superintendents, area managers, and land development project managers who help to manage daily stormwater compliance on our sites. At D.R. Horton stormwater is a team effort starting at the Corporate level trickling down to our specific Divisions, and everyone working together towards this goal helps to develop an effective program.”
We at D.R. Horton greatly appreciate the recognition of our stormwater program and it cannot work without our on-site superintendents, area managers, and land development project managers who help to manage daily stormwater compliance on our sites. At D.R. Horton stormwater is a team effort starting at the Corporate level trickling down to our specific Divisions, and everyone working together towards this goal helps to develop an effective program.”
Details
Urban team BLOG
Every month, the Warren Co SWCD Urban Team dives deep into the world of land development as it relates to stormwater pollution prevention. The blog covers topics like erosion & sediment control best management practices (BMPs), state and local regulations, retention/detention basins, and the conservation of our natural resources. Stay up to date with Development Digest by signing up for WCSWCD Urban eNews!
Categories
All
Basins
BMPs
Drought
Inlet Protection
Permits
Sediment
Seeding
Storm Drains
Water
Archives
October 2024
September 2024
August 2024
July 2024
June 2024
April 2024
March 2024
January 2024
December 2023
November 2023
October 2023
August 2023
May 2023
April 2023
February 2023
December 2022
November 2022
October 2022
May 2022
April 2022
March 2022
February 2022
January 2022
December 2021
November 2021