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Winter is Coming: A Quick Guide for Your Stormwater BMPs in Cold Climates

The leaves have changed and snow is beginning to fall in several places across the country. By this time, construction projects are frantically trying to wrap up grading, landscaping, and other outdoor tasks. But is your project overlooking a big stormwater task during this season?

As we know, northern winters in the U.S. can be brutally cold, snowy, or mild with little to no snow. Preparing your site to handle the winter will greatly reduce your stormwater best management practice (BMP) maintenance and allow a quicker return to work come spring. Here are a few tips and tricks project owners and supervisors should be considering:

1. The best winter BMP is established vegetation. Consider the germination time when preparing your site for the winter.

2. Seed & crimped straw is a recommended temporary stabilization technique for nearly all scenarios. Ensure the straw is properly crimped into thawed ground before freezing up conditions. October 15th is a key date to finish stabilizing soils in preparation for winter.

a. If winter has snuck up on you, stabilization is still required, but techniques change. Crimping is difficult or impossible after the ground freezes. The Minnesota Stormwater Manual has some great resources on snow mulching where they detail how to stabilize after winter has set in.

3. For projects in urban environments, evaluate your ability to move curbside perimeter controls (such as silt fence and filter logs) away from the curb to minimize snowplow damage.

4. Consider plow routes and locations where snow will be stored throughout your project site (if needed). Ensure perimeter controls will not be damaged as snow piles grow and melt run-off may concentrate and overwhelm BMPs.

5. If sanding and/or salting operations will occur on your site, consider the downstream cumulative effects to vegetation, soils, and permanent stormwater management features that are not fully constructed or established. Potential upgradient BMPs to divert flows from these areas may need to be installed before freeze up.

6. Clean your streets before any chance of freezing or snow. Sweepers and vac-sweepers are not able to work during the winter months. Skid-steers can be used to clean sediment from roads in the winter.

7. If your project is in Minnesota, inlet protections must remain installed throughout the winter. Several cities, counties, and watersheds have their own regulations that require inlet protections to be removed by certain dates, most are November 15th.

a. The Minnesota Pollution Control Agency does allow the temporary removal of inlet protections that if frozen, could create a public safety concern.
b. If any inlet protections are removed, or BMPs in general are moved or removed, documentation in the SWPPP is required.

8. Inspections can be suspended — if no ground disturbance is occurring —once your site has frozen ground conditions. However, if a warm-up occurs, weekly inspections do need to be started up again.

a. Additionally, if ground conditions remain frozen, but a day or two of warm weather occurs — after runoff, or post-storm event inspections, are required within 24 hours of the event. Runoff is defined as precipitation or melt water moving on site far enough to discharge from the site either via a perimeter control, or a permanent stormwater system.

Stormwater BMP
From the MPCA: Maintenance should continue through the winter months to ensure that inlet protection BMP is functioning properly.

Navigating the needs and requirements of your site through the winter is a handful, let alone the NPDES permit itself. If your project requires any assistance with planning, preparation, inspection, or more, please feel free to reach out. Braun Intertec and our certified inspectors would be more than happy to lend a helping hand.

Jamie Dayton Staff Scientist, Stormwater Specialist

P: 952-995-2000

Travis Fristed, PWS Group Manager, Senior Scientist

P: 952.995.2027