Where to pile snow, and where not to

Why does pile placement matter so much?

Snow storage is a decision that lasts all winter. A pile placed in the wrong spot in December grows with every storm, shades the ground beside it, and releases meltwater on every warm afternoon. In the valleys here, where days often rise above freezing and nights fall below it, that water refreezes into ice wherever it runs. The pile is rarely the hazard. What it drains onto is.

The Minnesota Pollution Control Agency's stormwater guidance makes the same point from the water side: snow from paved surfaces carries sediment, organic material, nutrients and chloride, and storage areas should be placed so that snowmelt does not drain to sidewalks and adjacent streets. Its advice is written for larger sites, but the principles transfer directly to a driveway.

Where should snow go on a typical property?

The best spots share a few traits. They are downhill or level relative to the surfaces you use, so meltwater runs away from drives and walks rather than across them. They are on ground that can absorb water, such as lawn or open soil, rather than pavement. They are reachable by whatever is clearing the snow, so storage does not require a second trip. And they have room to grow, because the pile in February is far larger than the pile in December.

MPCA's on-site guidance says to store snow on permeable surfaces where possible, to mark the edges of both the plowing area and the storage area so equipment does not damage them, and to use concave landscaped areas rather than mounded ones for storage. On a home that usually means an open stretch of lawn beside the drive, set back from beds and trees, on the low side.

Can you pile snow against the house or garage?

It is best avoided. Snow banked against a foundation melts against it, and the water has to go somewhere. Piles against a garage block doors and vents, and piles under eaves add to whatever slides off the roof. FEMA's Snow Load Safety Guide, written about roof snow, also tells people to keep removed snow away from building exits, downspouts, ventilation openings and equipment, which is sound advice for snow from the ground as well.

Downspouts deserve special mention. A pile under a downspout outlet traps the water the roof is shedding, and the ice that forms often spreads across the walk or drive nearby. If ice dams are part of the picture, see our guide to ice dams in Montana homes.

Is it a problem to pile snow over a septic system?

Yes, if it means driving or compacting snow over it. Montana DEQ's homeowner guide to septic systems lists lack of snow cover, cold temperatures and compacted soil among the common reasons systems freeze, and tells owners to keep all vehicles, including ATVs and snowmobiles, and high-traffic activity off the system all year. Nebraska Extension describes undisturbed snow as a natural insulator and warns that compacting drainfield soil in winter can force frozen solids into the drainfield.

The practical rule is to leave natural snow cover over the tank and drainfield alone, never plow across it, and never use it as a storage area where equipment has to drive on it. If you do not know exactly where your septic components are, find out before winter. DEQ's guide includes a page for sketching your system, and that sketch is useful to anyone clearing snow on the property.

Why keep piles off planting beds and away from trees?

Weight and salt. Plowed snow is dense and often mixed with gravel, sand and de-icer from the surface it came off. Dumped on a bed, it breaks shrub branches and holds that salt against the roots through the melt. Our guides to how de-icing salt damages plants and concrete and protecting shrubs from snow load and plow spray cover the damage in detail.

Trees near a drive are a common casualty. A bank pushed against a young trunk can strip bark, and repeated salt-laden piles around the root zone add up over several winters. If the only storage on a tight lot is next to valuable trees or beds, it is worth discussing hauling for the worst storms rather than piling.

Where do sightlines come in?

Where your drive meets the road, a pile on either side can hide oncoming traffic from a driver pulling out, and hide that driver from traffic. Snow that is pushed to the end of the drive tends to accumulate at exactly that corner, and by mid-winter it can be taller than a car. Keep the corners clear and store snow further back along the drive, even if it means a longer push.

The same goes for corners inside a commercial lot, where piles can hide pedestrians from cars. Our parking lot snow plan guide covers sightlines on larger sites.

Can you push snow into the street or onto the road?

Inside Missoula, the City's sidewalk snow removal page says plainly not to shovel snow into the street, bike lanes or parking lanes; snow from the sidewalk should go onto your own property. Our page on Missoula sidewalk snow removal rules covers the City's requirements in more detail.

On county and private roads, pushing a driveway's snow across or onto the road leaves a ridge that freezes and creates a hazard for every driver who comes next. Rules vary by jurisdiction and road, so if your drive meets a county road, check with the county road department before assuming anything. For shared private roads, our guide to who is responsible for plowing a private road explains how neighbors usually sort it out.

What about fire hydrants, mailboxes and drains?

Never bury them. The City of Missoula tells residents not to cover fire hydrants with snow because firefighters and Missoula Water crews need quick access. MPCA's guidance says snow storage should not be placed on top of drain inlets, which matters wherever a drive or lot has a catch basin or culvert. Mailboxes need a clear approach for the carrier. We cover both in mailboxes, hydrants and snow clearing.

Culvert ends under a drive are easy to forget and important to keep open, because spring runoff has to get through them. A culvert buried under a pile in January can send March meltwater across the drive instead of under it.

How does a rural Bitterroot property change the plan?

Acreage gives you more room and more ways to get it wrong. A long drive across open ground has storage along its whole length, but it also has wind. Banks built on the upwind side catch blowing snow and drop it straight back onto the drive, so on an exposed property it often works better to push snow well clear on the downwind side and keep the upwind edge low. A bank that grows into a wall turns a drive into a trench that fills with every breeze.

Rural lots also hide more under the snow: irrigation heads and valve boxes near the drive, a well head, the edge of a pasture fence, a ditch along the road, and sometimes a buried line for a shop or barn. Pushing a winter's worth of snow onto any of them is how they get broken. Irrigation that was winterized in fall still has heads and boxes that a heavy pile or a blade can crack, so mark them before the ground is white.

What happens to a pile when it melts?

It shrinks from the top and the sunny side, and the water runs downhill under the snow before you see it. A pile at the top of a gentle slope toward the drive can put a sheet of ice across the pavement every evening in late winter, even when the pile looks small. Looking at where the ground slopes, rather than where there is space, is the single habit that prevents most melt problems. If the only open space drains toward the drive or the house, it is the wrong space.

Melt also brings up whatever went into the pile: gravel off a gravel drive, sand, de-icer, and the odd piece of debris. Expect a layer of grit where a big pile stood, and expect the turf beneath it to come up late and matted, which is one reason to keep piles off the best parts of the lawn.

When does it make sense to haul snow away?

When the storage runs out. On tight lots, in-town properties and most commercial sites, piles reach the point where they consume parking, block sightlines or threaten buildings and plants. At that stage hauling is cheaper than the damage. Our commercial snow and ice management work includes off-site hauling when piling stops working, and we plan that with clients at the start of the season.

MPCA's guidance also recommends cleaning designated storage areas of accumulated sand, trash and debris before and after winter, and repairing any erosion. On a home that means raking out the grit when the pile is gone, which is part of a normal spring snowmelt yard cleanup.

How do you plan storage before winter?

Walk the property in fall with whoever will clear it. Decide where snow from each surface goes, mark the edges of beds, the drive and the storage area, locate the septic system, culverts and drains, and note where meltwater runs today. Our guide to snow stakes and markers explains what to mark and how, and snow plow damage prevention covers what tends to get hit.

Agreed snow storage is part of our residential snow removal setup and our wider snow and 24-hour storm services. This guide is part of our Montana Winter Property Guide. To plan storage for your property, call (406) 215-7319 or request a free estimate.

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