Launch Slideshow

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Where does the snow go?

Where does the snow go?

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    Quebec City's recipe for success: After trucks discharge, a plow, excavator, and blower work in concert to pile snow up to 72 feet high to make the most of dump space. Images: Quebec City Public Works Department

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    Trucks unload in a designated discharge area (bottom photo), while a blower piles the snow bank higher at the other end of the site (top). Snow that's been collected by loaders is piled separately and used as an abutment to prevent avalanches, and previously blown snow is added on top by the heavy-duty snowblower without fear of damage from foreign objects.

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    Rectangular site shape

    For maximum efficiency, Quebec City uses a rectangular site design with two discharge areas. Signalmen direct fully loaded trucks to one area to discharge before exiting the dump, while a blower in the other discharge area processes previous loads. Both sides work from the outside of the site toward the middle.

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    Decantation basins at dump sites retain water runoff and sediment until it can be analyzed and removed in spring. Only the lightest 10% of sediment from melted snow ends up in the bottom of the basin. About 90% stays on the dump site, where it's cleaned of all debris once the snow has melted.

Site drainage

Before they receive a single load, dump sites are designed with a peripheral drainage ditch to collect water and graded to ensure proper runoff. Water collects in a decantation basin on one end, where it flows through an oil and grease separator before leaving the site. Sediment settles to the bottom, where it's periodically analyzed and reused or discarded according to environmental regulations.

The signalmen also separate trucks filled with snow by loaders from those filled with blown snow. The snow collected by loaders may contain larger objects that can break the dump site snowblower and paralyze operations.

As the trucks enter and leave the site, each driver's radio-frequency pager tracks delivery time and location. A validation device on the street snow-blower contacts the pagers to confirm each trip, so dump operators know where the snow has been collected and can confirm that no snow is being brought in from private areas.

At the site gate, information from pagers is automatically transferred to the city's accounting and payroll system, which calculates driver pay by volume based on truck capacity information provided by the contractor. At the end of the season, Langlois and contractors review the data, including the average amount collected in each zone, to tweak contract specifications for the coming year.

Half of the city's snow removal and all snow dump operations are handled by independent contractors, so the time and money saved by streamlining payroll and contract negotiations is significant.

Managing runoff correctly

Each Quebec City snow dump is designed with a peripheral drainage ditch to collect the runoff created by melting snow and rain. Before the Province of Quebec Ministry of Environment approves the construction of a new site, its design and location must meet many environmental specifications, especially those related to water protection and treatment. For example, the land must be properly graded to ensure water runs to a decantation basin at one end.

Here, sediment naturally settles to the bottom; public works removes and analyzes it once a year. If contamination levels are low, the muddy residue is reused in construction projects — for instance, to create banks at other snow dump sites.

Dumps return runoff to natural sources, so before leaving the site runoff goes through an oil and grease separator to remove residue from snow collected on streets or equipment leaks. “We try to use nearby streams, but they must be large enough to dilute the salt that remains in the runoff water without harming the environment.”

His advice for designing a decantation basin:

  • Ensure adequate capacity by calculating the number of inches in a heavy rainfall and adding the amount of snow that melts within one hour. Assuming the water in the basin is 3 feet high, you can determine the necessary surface area based on this maximum projected volume.
  • Verify the need to waterproof the basin, which is determined by the nature of the site's soil and local groundwater usage. The Province of Quebec Ministry of Environment, for example, requires basins to be lined with waterproofing fabric.
  • An elongated basin shape is most efficient.

A significant investment

Langlois is planning a new snow dump to replace smaller sites. The city will spend $12 million on the site — $6 million for land, and $6 million on construction.

Quebec City owns 12 of its 14 snow dump sites, a practice Langlois recommends. “If the land is owned by a private company, they can always raise the price when the contract is up and the location is even more in demand,” he says.

Although the new, 2.6-million-cubic-yard site is farther from the city and will add $300,000 to annual snow removal operations, he considers it a sound investment. “It's an old stone quarry with a 100-foot deep pit,” he says. “It will accommodate future development of the city and handle exceptional amounts of snowfall — and excavation materials if needed. This site will generate financial benefit for the next 20 years.”

For more information, contact Eric Langlois at 418-641-6411 or eric.langlois@ville.quebec.qc.ca.