Sledding In July: Snow-Saving Experiment Tapped For Holiday Merriment

Jul 5, 2018

The sun was beating down and temperatures had climbed into the 90s as an annual block party in Craftsbury got underway this week. But a thick strip of snow in the backyard of one village home made it — by far — the coolest place in town.

The Craftsbury Outdoor Center brought over a half-dozen dump truck loads of snow and neighbors with tractors helped spread it out into a sliding track, complete with a stack of sleds.

Where did the Outdoor Center get all this snow in the middle of a heat wave?

Well, they saved it.

In April when ski season was over, they pushed the snow into a pile and covered it in plastic and wood chips.

Judy Geer works on smoothing out a track of super dense saved snow.
Credit Amy Kolb Noyes / VPR

This week they uncovered the pile, one of two they’re monitoring at the Outdoor Center.

"We’re experimenting with storing snow," explained Outdoor Center co-owner Judy Geer, "because the climate is changing and it’s not enough to have snowmaking anymore because you might not get weather cold enough to make snow. And so, this way if we make snow when the weather’s really cold in the wintertime and save it, that way we can make it when it’s more energy efficient and environmentally effective."

Researchers think the collapse in this pile is due to a change in conditions where two sheets of plastic met under the woodchips. Of course, direct sunbeams don't help the situation.
Credit Amy Kolb Noyes / VPR

It’s not a new concept.

Geer says a number of Nordic race venues in northern Europe, and even Canada, save snow.

In Europe, it's done as far south as southern Germany. It’s basically the same technique our ancestors used when they covered blocks of winter ice with sawdust in ice houses, before refrigeration.
Geer hopes to gather enough data from this summer’s test piles to scale up the experiment next year.

And they’ve got some help.

UVM Professor Paul Bierman and grad student Hannah Weiss stand on what is left of a saved snow pile after several truckloads were hauled to Craftsbury village for the celebration.
Credit Amy Kolb Noyes / VPR

"We’re lucky to have a UVM grad student, Hannah Weiss, and her advisor Paul Bierman working on this," Geer said, "helping us figure out what is the best insulation and ... what are all the considerations that make this work as optimally as possible."

Bierman uses his phone to check Bluetooth temperature sensors in a second pile of stored snow at the Craftsbury Outdoor Center.
Credit Amy Kolb Noyes / VPR

Even once they refine their technique, Geer says a third of the snow they save in the spring is likely to melt away before they need it again in November.

But if they can store enough snow, they can cover a kilometer or two of trail for early season training.

Once the last load of snow had left for the block party, what’s left of the pile is re-covered with wood chips.

No plastic this time. One of the first things they learned is that the seams in the plastic caused fissures in the snow pile. And the plastic also made it too slippery for the woodchips to stay in place.

Next, Weiss and Bierman check their measurements. Weiss takes a sample to measure the snow’s density.

Meanwhile, temperature sensors have been collecting data at four different depths in the snow pile and the ground beneath it. Because, as Weiss explains, it may not be just warm air and sun that melts the snow.

"We were trying to figure out if [the] ground temperature had a huge influence on melting a snow pile," she said. "And if this ground temperature was able to make it to zero then we could say, alright it makes the sense to keep the snow directly on the ground because it’s getting cooled to zero degrees anyway."

UVM graduate student Hannah Weiss assembles the LiDAR surveying equipment.
Credit Amy Kolb Noyes / VPR

That's zero degrees Celsius – freezing.

They use a Light Detection and Ranging (LiDAR) surveying system to measure how the snow pile changes over time.

"And it is laser software that essentially shoots light beams out and measures return time," Weiss explained. "And so it can take surface images and it creates these highly detailed 3D maps."

"So when Hannah’s measured these volumes over the last three months, we can watch the steady decline with really high precision," adds UVM Professor Paul Bierman.

Hopefully, with enough data, they can figure out how to slow the snow’s decline in years to come.