Stormwater Winter Preparedness Checklist
By Jason Abert, Vice President, Service Delivery
Where you are making your list and checking it twice, be sure to include your preventative stormwater maintenance ahead of winter weather as a priority on your to-do list. Preparing stormwater systems before the temperature shifts is essential because once the ground freezes and snow begins to fall, the frozen conditions can hinder infiltration. As a rule, preparations should begin when water temperatures consistently fall below 60 degrees Fahrenheit.
It is important to note that most action taken before winter is preparing for the upcoming spring, not the looming winter. This is because winter conditions typically delay precipitation's impact on stormwater systems, collecting in solid forms as snow, ice and hail on top of impervious surfaces – which now includes frozen soil - where it is stored until the temperature warms and melting can occur.
The melting period in early spring is when many preventable stormwater system failures occur. This is due to the high concentration of pollutants that have collected, plowed and piled for months before melting all at once. This first flush of meltwater is the most polluted stormwater, harboring chemicals, trash and debris that can pollute local watersheds and lead to stormwater system failures, costly NOVs and untreated stormwater reaching your community's watershed.
Winter preparations recommended by AQUALIS' certified stormwater professionals include;
Support established vegetation
Your winter checklist should include preparation for established vegetation to support the plants throughout their dormancy. Adding extra mulch around plant bases protects against erosion, suppresses weed growth, and protects the plants from frost and moisture loss. Before winter weather strike is also an excellent time to evaluate systems for dead or dying vegetation. Weakened vegetation can be easily dislodged and washed away during winter storms and spring runoff influxes, leaving systems at risk of clogs. Removing the impaired vegetation during winter preparation mitigates this risk and allows for supplemental plantings to occur, as previously mentioned.
Remove loose materials
Before pre-winter weather, it is also essential to remove excess organic matter, including leaves and twigs, from stormwater assets, including catch basins, detention basins and parking lots. An abundance of leaf litter and other debris can clog stormwater systems as runoff carries the materials deeper within systems and underground pipes. These clogs are especially dangerous as they may go unnoticed throughout the fall and winter but cause systematic system failure during intense snowmelts or spring storms. Due to the large amounts of runoff in a short period, a system failure during this time could result in severe property flooding, emergency response and costly repairs. Proactively cleaning your stormwater system can protect your property from disaster. Failure to remove excessive organic matter can harm local wildlife, contributing to nutrient overload as the decomposing plant matter releases excess nutrients into the water while removing dissolved oxygen during the decomposition process.
Clearing catch basins, permeable pavement and smaller pipes of all loose materials are important before the first freeze to prevent debris from becoming trapped and leading to clogs. Depending on the system, sweeping, vactor and jetting are all vital cleaning tools to remove sludge, debris and trash from systems before winter.
Reduce holding water volume
For systems that allow, reduce the holding water volume during the winter into spring. The reduction in volume allows more space for the impending snowmelt, preventing the influx of runoff from overwhelming systems as the weather begins to warm.
Reduce sand, salt and chemical treatment usage
Deicing treatments are utilized throughout winter to keep roads clear of ice and increase driver safety. However, overuse of deicers can lead to waterway degradation in local communities. Excess materials get washed away as the melting agents prevent ice from forming, contributing to increased watershed salinity, turbidity and other negative water quality impacts. These materials can also become trapped within stormwater systems, leading to clogs and sedimentation. If continued sedimentation occurs over time without maintenance, the level of stormwater basins could rise, leading to a reduced storage capacity and increasing a property's flood risk.
Careful where you plow
Keeping your system's requirements in mind when managing snow removal is essential. For example, permeable pavement should never be plowed as the soft, porous material could be damaged or clogged. In addition, permeable pavement systems typically do not require any snow removal as infiltration and their connection to the warm ground allow for natural slush reduction and, therefore, black ice reduction. However, proper maintenance is necessary to prevent compaction from preventing infiltration. Check with your manufacturer's guidelines for the recommended maintenance schedule before and after winter.
While there are conflicting opinions, our recommendation is to not pile snow into stormwater systems or on stormwater vegetation as this may clog systems and damage vegetation due to the high concentrations of pollutants. Instead, pile plowed snow on porous materials outside of stormwater systems. Typical non-compacted snowfall cover is not harmful to stormwater systems, so there is no need to shovel the snow or plan for removal. For example, snowfall in a detention basin does not need to be cleared or removed.
Install Safety Signs
If you have a pond on your property, we recommend installing seasonal winter safety signs to inform passersby of the potential dangers. Stormwater ponds are not safe for winter activities, including ice skating or sledding and no one should ever stand on the ice for any reason. These systems are designed to collect stormwater runoff, which can contain deicing materials such as street salts throughout the winter. These deicers cause the ice present within stormwater systems to melt and thin at unpredictable rates, making it unstable and unsafe to stand on. In addition, water is constantly moving through stormwater systems under the frozen surface, with dangerous currents that could pull even experienced swimmers underwater. This continual flow also contributes to ice degradation, making it hazardous and unsuitable for winter.
As you prepare for winter, please keep your stormwater systems in mind.
Partnering with a trusted stormwater provider like AQUALIS ensures your systems are prepared for the changing seasons, snowmelt, and any other challenge your site might face. Contact AQUALIS and schedule a FREE consultation with your local representative to learn more.