Waking up to a gentle dusting of frost on the ground this week has gotten our office excited for upcoming snowy weather activities – and those of us on the Stormwater Team are eager to talk about preparing your stormwater control measures for the winter!
One stormwater feature that gets hit the hardest during a typical Ohio winter is permeable pavement. Whether it’s permeable asphalt, concrete, or pavers, now is a great time to get one last look at your parking lot, driveway, or sidewalk and get everything set up to ensure it's able to properly drain during freezing rain and snow.
Permeable pavement works by allowing water to infiltrate through a porous surface where it is stored in an underlying stone layer, allowing sediment and pollutants to settle out while water slowly infiltrates either into the ground or through an underdrain that’s connected to a storm sewer.
Keeping the porous surface clean so it is able to drain freely is the most important maintenance task when it comes to permeable pavement, and it’s the first step in preparing these features for winter. Dirt, trash, and fine sandy sediment built up between grains of permeable concrete/asphalt or within the stone aggregate of brick pavers are the most common clogging agents that slow the infiltration of water into these stormwater control measures. If these clogs need to be cleaned, buildup can be removed from small sections using a shop vacuum or leaf blower, or by a regenerative air sweeper for larger areas. If it’s too late this year, keep in mind any areas that you see are ponding water and schedule maintenance for the spring to remove and replace any clogged aggregate.
During freezing weather, it is important to remember that permeable pavement works differently from traditional hard surfaces and will need to be treated with care when snow and ice accumulate. The layer of uncompacted stone that sits beneath the porous upper layer of permeable pavement is filled with air, until a rain or snowmelt event occurs and these voids are filled in with water. Air is a great insulator, and the air pockets beneath permeable pavements can - in some cases - keep these surfaces warmer for longer, reducing the overall snow and ice buildup compared to traditional impervious pavements. During milder winters, permeable pavements may only need to be plowed or salted a handful of times.
When it comes to applying salt, less is better! Soil & Water emphasizes using less de-icing salt for all slippery surfaces in Cuyahoga County (learn more and take the S.A.L.T. pledge below), but it is especially important to minimize salt applied to permeable pavements to keep the whole system working properly. Applying too much salt can break down the binding on porous concrete and asphalt, causing the pavement to break apart and clog itself. Additionally, applying a large amount of salt negatively impacts the water quality of snowmelt leaving the system. Regularly check icy conditions on a porous surface and only apply salt when needed. If things start to get slippery, please note it is NOT RECOMMENDED to spread sand to increase traction when there are permeable pavers nearby. Sand will fill in the porous surface and cause clogs that will need to be cleaned once snow melts.
Keep snow piles away from any stormwater control measures on site when plowing or shoveling. This rule of thumb applies to all stormwater basins, bioretention cells, and – you guessed it – permeable pavers! Snow piles are full of trash, grit, and debris that percolates down into permeable pavement as it melts, making it difficult and expensive to clean in the springtime. Additionally, heavy snow piles can overload and compact the underlying stone aggregate or break apart the binding of porous asphalt/concrete, causing settling that decreases the total pore space which allows water to infiltrate.
Plowing permeable pavers comes with a few special considerations as well. Specifically, brick pavers are held in place by a layer of loose stone aggregate, so using a hard tipped metal snowplow can cause the blade to catch onto a brick and knock it out of place. Losing a brick then allows the aggregate to settle into the void space left behind and make it difficult to get the brick back in place and level with the rest of the pavers. For this reason, it is recommended to use either 1) a rubber tipped snowplow blade or 2) raise the blade ½-1 inch above the surface to prevent any damage to the pavers.
Make sure to treat permeable pavements correctly over the winter and they can last up to 20 years! That’s two full decades of water quality benefits for the small price of keeping your parking lot clean.
For more information about routine and non-routine maintenance of stormwater control measures, you can download the “Maintaining Stormwater Control Measures” manual using this link: SCM Manual
To learn more about applying less de-icing salt, check out and sign our environmental pledge here: CSWCD Environmental Pledge
Blog Author: Lauren Conard, Urban Technician