Why Low-Snow Winters Are Bad for Shorelines (and How We Can help)
Many people call us after discovering their shorelines have been battered by ice ridges. Their shorelines have been pushed up by a giant hump of ice – an ice ridge – that sits about 5 feet from the shoreline. This hump might be anywhere from 1 foot tall to 8 feet tall. It usually knocks your shoreline into disrepair.
An ice ridge is formed by what’s called “ice jacking.” It happens most often in winters where little or no snow falls, and it’s even more of a problem when accompanied by colder-than-average temperatures.
How ice jacking works
Winter temperatures are not constant. Typically, temperatures are warm during the day, often rising above freezing. At night, they plunge below freezing once more.
During the warmer periods of the day, the frozen lake must expand with the rising temperature, and therefore will crack as the expansion takes place. Those cracks in the ice sheet will instantly fill with water from beneath.
At night, the temperatures plummet and those cracks (now filled with water) freeze once more, before the ice sheet is allowed to contract. The cycle begins anew the very next day, and continues on throughout the winter. Each and every time the ice cracks, fills with water, and refreezes, the sheet of ice expands and grows in size.
As the ice expands inch by inch, constantly cracking and refreezing – a ratcheting effect – the ice slowly moves towards the shoreline. Now it begins to push against the shoreline, causing an ice ridge. It will push anything: dirt, boulders, foundation walls, or whatever else might be in its path. It’s hard stop several tons of ice from going where it wants to go.
Why snow matters
When you don’t have a lot of snow cover, there’s nothing to insulate the ice from the relative heat of the day, particularly sunrays. People don’t think of snow as an insulator, but it is a great one. (For one thing, that’s why piles of snowplow snow can take months to melt.) Without a layer of snow to stabilize the high and low temperatures, the cracking, melting, and re-freezing process I described will be more severe than it would be during snowier winters.
If you live on the lake and don’t care much for snow, you may want to think twice before thanking Mother Nature for the mild winter. She’s putting your shoreline through the wringer.
How Lakeshore Guys can help
We can help by solving the most pervasive problem with shorelines: the lack of tapering. We’ll build you a shoreline which has the correct slope.
Most shorelines have a steep slope or a drop-off to the water, or both, typically caused by erosion. In the winter, the expanding ice will mash that steep slope or ledge into Gerber baby food. That’s why we never recommend retaining walls along shorelines. Ice won’t slide up a vertical wall, but it will push the wall out of its way. The same is true of big boulders. Large boulders, greater than 30 inches in diameter, will only exacerbate your ice-ridge problems.
The slope of your shoreline is important. We create a 3:1 or lesser slope, whenever possible. What we want is for the ice to slide up onto the riprap, rather than plow directly through it.
Ice takes the path of least resistance. In most cases it’s easier for that ice to push up and over the riprap when we’ve given it a proper slope. That’s what we want it to do. If everything works in your favor, the ice will only devour a few easily replaceable riprap rocks, which you may want to replace in the spring. But at least you won’t have to rebuild your whole shoreline.
Does riprapping your shoreline guarantee no more ice jacking?
Unfortunately, no. Mother Nature is unpredictable, and she doesn’t always want to work with us. Sometimes she’ll push the riprap and everything else right out of her way. Still, we’ve watched properly sloped, riprapped shorelines put an end to ice jacking and ice ridges more times than not. You’re better off with riprapping than you are without it.
Of course, this is only true if you’ve hired a company that will do the job correctly. If you just throw fabric and rock down onto the shoreline without adjusting the grade you won’t have any defense against ice jacking whatsoever. You’ll get a few years or more of protection against erosion, but that’s about it. Whatever state your shoreline is in, if it’s vertical, has a slope steeper than 3:1, or has the slightest lip of soil along the water’s edge, it will lose the battle with ice. You can be virtually guaranteed you’ll be looking at a giant ice ridge along your shoreline come spring.