15 Stormwater Best Management Practices for Construction Sites

Developing a stormwater management plan is federally required to obtain an NPDES permit for water discharge at a construction site. 

There are many methods to reduce stormwater pollution, from using natural mulches that prevent soil erosion to constructing artificial barriers that trap sediment. 

In this article, we’ll detail fifteen crucial stormwater best management practices, including tools and strategies you can use to reduce stormwater pollution, remain legally compliant, and save money. 

1. Limit Land Disturbance

Reducing the amount of surface land disturbance will reduce the amount of erosion and sediment that can run off during a storm. In turn, you won’t have to invest as much money in artificial barriers and controls to prevent soil erosion. 

In addition, many natural spaces, such as forests and natural vegetation, are great at increasing water infiltration, slowing the speed of stormwater runoff, and even increasing evapotranspiration (the rate at which water evaporates from the ground to the atmosphere). 

One tip we suggest is confining worksite equipment and vehicles to specific and small confined areas to minimize total land disturbance, whether it’s from physical construction activity or even transport. 

Keep washout stations separate but confined to workspace areas, as well as portable toilets and break stations where crew members will tend to congregate. 

2. Preserve Natural Vegetation

Preserving vegetation provides the added benefit of reducing the time and money spent on revitalizing a work zone. 

Plan to conserve natural features when designing a worksite, such as redirecting roads around forests and gardens where vegetation can aid in stormwater runoff. 

Likewise, be conscious of damaging trees when constructing fencing or roads, as this could be dangerous. 

Take soil samples and evaluate the age and condition of trees before clearing them to determine if they may be helpful far down the road. For example, evergreen trees can help shield building structures from cold winds during the winter, helping buildings conserve energy. 

3. Increase Water Infiltration

Water infiltration is the process of absorbing water through soil and other natural features as it travels over the land surface. Increasing water infiltration using well-aerated soils and natural vegetation helps reduce the total volume of water being discharged from a worksite. 

There are many natural ways to increase infiltration, including:

  • Crop rotation
  • Employing a diversity of plants
  • Reducing soil compaction
  • Reducing soil tillage
  • Covering plants and exposed soils with cover crops
  • Applying fertilizers

In addition, there are many artificial tools at our disposal, including permeable pavements that absorb water instead of letting it flow unimpeded like concrete or asphalt. 

4. Use Man-Made Erosion Controls

Erosion and sediment control is a massive concern for construction crews because runoff can mix with dirt to pollute water systems. 

Reducing topsoil erosion is the easiest way to prevent sedimentation, increase infiltration, and slow the spread of stormwater runoff. Some erosion best practices include:

  • Applying mulch to slopes
  • Using erosion control blankets on exposed soils
  • Using vegetative coverings to protect surface soil
  • Applying temporary seeding to disturbed soils

5. Grade Slopes to Reduce Their Runoff Coefficient

Another effective method to reduce topsoil erosion is to reduce the velocity of runoff relative to their rainfall–otherwise known as the runoff coefficient. One way to do this is by physically altering the slope of a hill to reduce water concentration in one area. 

For example, by grading slopes with radial drainage patterns, you can prevent water from rushing down a hill at one particular curve and destroying the soil exposed in that area. 

6. Use Downspouts and Swales to Redirect Stormwater

Similarly, you can reduce the runoff coefficient of a slope by redirecting stormwater with several different control mechanisms, including downspouts, swales, and bioretention areas. 

Downspouts can be applied to specific parts of the slope to redirect stormwater to the bottom without exposing the soil on the hill. 

Vegetative or rock swales are similar to ditches that help slow the flow of stormwater runoff and even trap some of it. Likewise, bio-retention zones allow for the natural infiltration of vegetable-rich soil. 

7. Capture Sediment Laden Water

Once significant erosion has occurred, loose sediments can leak into the water, causing pollution and turbidity that kill off marine life. However, several tools are at an operator’s disposal to trap sediment-water and treat it before discharging it back into public water systems. 

Silt fences, compost bags, fiber logs, and filter bags can be applied at the top and base of slopes to help trap large sediment particles and separate them from onrushing stormwater. Added precautions, such as detention basins, can be built at the bottom of hills to hold large quantities of stormwater so that they can be treated before discharge. 

8. Use Storm Drain Filters and Protection

Storm drain inlet protections and filters can be applied around storm drains as a last line of protection to separate sediment before it’s discharged into municipal sewage systems. 

9. Eliminate Curbs and Gutters Until Construction Has been Completed

While gutters and downspouts protect worksites from damage, they can jeopardize your stormwater management efforts if not carefully controlled. Since gutters tend to divert water away from buildings anywhere it can, you need to be strategic about how you set up gutters and curbs, which tend to concrete runoff in specific areas of your construction zone. 

10. Create Special Bays for Vehicle Washouts

Many state and federal agencies prohibit discharge from commercial vehicle washouts into public water systems. Instead, worksites will need to use portable wash pads or a compliant commercial car wash system. In addition, it’s recommended that all storm drains near washout stations are properly protected to prevent unlawful discharge. 

11. Properly Store and Cover Worksite Materials

Most SWPPPs feature provisions for worksite material handling and storage, as runoff from these materials can contain several toxic substances, including paint, stucco, concrete, and more. 

Create special provisions to store and cover these materials in a safe area where they will not be exposed to the elements. 

12. Train Employees and Subcontractors on Procedures

Train all crew members and subcontractors responsible for maintaining these BMPs to ensure they follow proper procedures. We stress training subcontractors as many operators tend to overlook them, though they are still liable for any mistakes they make on a job site. 

13. Conduct Frequent Inspections

Shore-up operations by conducting frequent inspections with a qualified consultant to ensure that all stormwater best management practices are being followed. Inspections should range from equipment handling to physically assessing the state of your erosion controls to ensure they are stable. 

One vulnerability or weakness can result in stormwater pollution, so federal agencies recommend conducting an inspection every seven days or within 24 hours of a severe weather event.

14. Hired Qualified Personnel to Draft an SWPPP

Dot every “i” and cross every “t” by hiring a qualified consultant to help you draft your SWPPP. Most construction general permits require hiring one anyway, but be sure to find a consultant that you trust and has the experience required to draft a proper SWPPP that will protect your business. 

15. Stabilize Workzones After Construction Has Ceased

Last, and certainly, not least, you’ll need to stabilize worksites after construction has ceased. Fortunately, by following the strategies above, you’ll invest significantly less in reseeding and replanting disturbed vegetation to avoid liability. 

Stormwater management is an essential part of protecting our environment. Let the experts at Path Light Pro help you draft an SWPPP that targets all potential sources of pollution and protects your business from liability. We have the experience and knowledge to help you navigate every regulation and save money on stabilization efforts.