Stormwater management is an active measure taken by the Clean Water Act to reduce water pollution generated by construction and industrial activity.
Virtually any company that disturbs land over one acre in length and discharges stormwater runoff into public water systems must develop a stormwater management plan or SWPPP to acquire proper permitting to begin operations.
Part of developing that plan involves using stormwater BMPs or best management practices, which help reduce stormwater pollution via design strategies and active structural solutions.
What Are Stormwater Best Management Practices?
Stormwater best management practices (BMPs) involve a list of active measures designed to reduce stormwater pollution.
Generally, we divide these BMPs into two categories: planning/design and structural BMPs. The former seeks to conserve natural habitats as much as possible to reduce the level of pollution generated from any worksite. At the same time, the latter is designed to redirect, capture, and filter stormwater runoff to physically remove any toxins.
What Are the Importance of Stormwater BMPs?
Stormwater pollution may arise in many forms. For example, harmful VOCs and chemicals may leach out of construction materials during rain storms and pollute the runoff. Likewise, loose sediment from severe topsoil erosion could cause spikes in turbidity among local streams, leading to a loss of aquatic life.
Stormwater BMPs are designed to reduce these risks and encompass a broad range of activities, from constructing physical structures that filter out sediment to training employees on properly storing or covering toxic materials.
To better understand stormwater BMPs and stormwater management, we provided a complete list of stormwater BMPs that your company or home can incorporate to reduce its risk of stormwater pollution.
Stormwater BMPs: Planning and Design
Planning an SWPPP gives companies time to survey land and plan around natural features that give it the best advantages in controlling stormwater runoff.
By actively using natural features, such as riparian barriers and native vegetation, and by limiting the amount of land a project disturbs, it can reduce the need for structural BMPs and make revitalizing an area even easier.
Minimize Land Disturbance
Reducing lot size and preserving natural flow paths gives worksites an immediate advantage to set up as few controls as possible, thus saving money. We recommend confining worksite transportation and operation to as small of an area as possible, including construction work, vehicle washouts, and even lavatories, which minimize the amount of runoff from a site you need to control.
Reduce Soil Compaction and Improve Infiltration
Natural vegetation and soil is your best friend when it comes to slowing and absorbing ongoing stormwater runoff. However, compacted soil from repeated foot traffic, excavation, and vehicles can make the soil less amenable to infiltration, leading to more runoff.
Confining transportation to small pathways will reduce the amount of compaction, as well as waiting until the soil dries to work or excavate an area. You can add organic compounds that will make the soil more absorbent.
More ways to include infiltration include:
- Limiting soil tillage
- Rotating crops
- Preserving natural vegetation
- Using fertilizers and biostimulants
Revegetate Disturbed Areas
Natural vegetation serves several purposes besides reducing erosion, including:
- Promoting biodiversity
- Reducing weeds
- Improving landscaping
Be sure to replant and reseed any vegetables you use to aid in revitalization efforts and protect the soil against erosion.
Protect trees as well, which help stabilize ecosystems and conserve energy usage during extreme weather months.
Preserve Riparian Barriers
Another form of natural vegetation worth reserving is riparian barriers on the sides of rivers and streams. Essentially, these barriers consist of vegetation or rocks that act as a natural buffer that filters out sediment and other heavy contaminants from runoff before it enters public water systems.
Properly Channel Gutters and Curbs
While gutters and curbs are essential parts of any building, they can make managing stormwater runoff much more difficult if they are not properly channeled. Adjust them to direct water toward active structural BMPs, such as silt fences or detention bases, to reduce the risk of polluted runoff draining into public sewage systems.
Promote Proper Material Storage and Cover
Worksite materials, such as concrete and paint, can be a significant source of pollution. Practice proper storage to reduce their exposure to outside elements and train staff on proper storage procedures.
Separate or Cluster Discharges
Most construction permits limit what type of water you can discharge into public water systems. Based on that, you may need to separate vehicle washouts and discharges from public urinals to other sources, such as municipal car washes or portable wash pads.
Reduce the amount of dust and debris that can wash down drains with regular street sweeping.
Invest in Proper Training
Finally, ensure that all employees and subcontractors are bought into your mission and follow proper stormwater protocols to reduce your risk of an accident. Your SWPPP will require you to list members of your stormwater pollution response team and create an action plan for a spill or accident response.
Stormwater BMPs: Active Structural Solutions
In most cases, you must invest in active structural BMPs to reduce the risk of erosion and sedimentation.
Erosion Control BMPs
In terms of design, we stress the need to focus on erosion control. Reducing erosion reduces the risk of sedimentation, which is much harder and more expensive to contain. Reducing erosion also simplifies revitalization efforts, so use any stormwater BMPs listed below to help.
Grading slopes with radial patterns or reducing the runoff coefficient prevents stormwater from being concentrated in one area, leading to erosion. Work with an excavation team to adjust slopes to help redirect and filter water as it pours out of a worksite.
Downspouts or pipes effectively channel water away from slopes and into detention bases, swales, or other structures that allow water to sit until it can be filtered. They also reduce the risk of erosion on hills or slopes.
Swales can be natural or artificial basins at the bottom of slopes, which allow water to rest until it can be filtered or channeled. Swales serve the dual purpose of increasing water infiltration and allowing suspended articles to be filtered until they can be channeled to an appropriate discharge point.
Exposed soil on hills and flatlands can be covered with natural mulch that you can buy at the store or make from any vegetation you disturb to protect the top surface from erosion. Mulching also helps prevent weeds and feeds nutrients into garden beds.
Erosion Control Blankets
An artificial alternative to mulching is erosion control matting, which consists of straw, cotton, or wood, designed to protect the top surface from erosion while allowing sunlight and moisture to pierce the soil.
Permeable pavement is an artificial product similar to concrete, but it absorbs water, allowing stormwater to be slowed down as it rushes toward discharge points.
Sediment Control BMPs
When erosion controls are not enough to prevent sediment erosion, you must filter out these particles using these BMPs.
Silt fences are made up of a synthetic fabric, which allows water to seep past but filters out heavy sediments as it passes through. These fences are held up by metal or wooden posts and can be installed nearly anywhere on a slope where stormwater flows tend to concentrate to act as a filter.
Straw wattles are thick cylindrical barriers that can serve as an added defense for silt fencing, filtering out chemical VOCs, dust, and sediment as water passes through. Compost bags and fiber logs can also be installed at the bottom of slopes for the same purpose.
Retention pond maintenance requires the most work of any stormwater BMP, but a retention pond is highly effective at treating sediment-laden water. These basins are located at the bottom of slopes and are designed to capture water and hold it until it can be treated with chemicals or a purifier and then appropriately discharged.
Storm Drain Inlet Protection/Filtering
Lastly, storm drains and discharge points should be protected with inlet protection devices, such as filter socks, that trap sediment before it can be discharged into the drain.
The Importance of Ongoing Stormwater Management
While these stormwater BMPs promise to help reduce pollution and keep your worksite legally compliant, you’ll still need to perform frequent inspections of all equipment and add amendments to your SWPPP as vulnerabilities are discovered.
Let the experts at Valor Environmental help you design the perfect stormwater management system and maintain it through the life of a project.
Our team has decades of experience developing and managing stormwater systems. Contact us today to get started on the path of creating an SWPPP or inspecting your current stormwater BMPs.