Geology and Winter Roads across the north

Create: 12/01/2015 - 19:22

When the daylight gets shorter, the temperature drops, and the lakes, rivers, and muskeg begin to freeze across the Far North, thoughts turn to the winter road season.
As the snow falls, the groomers set out to pack the snow so the frost goes deeper into the ground and the ice on the lakes gets thicker. Building the winter roads is an art and skill. Winter roads are essential transportation networks across the Far North. Winter roads are an important means to deliver fuel, building supplies, and groceries to remote communities. Winter roads connect communities.
Role of Geology
There are geological factors that affect the construction and maintenance of winter roads and all-season roads.
Geology is a field of science that helps us understand the materials that make up the land and the shape of the land. It helps us identify sources of aggregate (sand, gravel or strong rock) used to build both winter roads and all-season roads.
Because of their geological properties, dry, flat, sandy areas are excellent places to locate a winter — and all-season — road as this material does not turn into mud as a result of repeated freezing-thawing. High and dry landforms make a stable winter road bed compared to muskeg and lakes. A rocky area is one type of dry stable land, but not all rocky areas are good to build on. Steep rocky hills or cliffs are not suitable for winter road construction.
Cliffs are impossible to drive over and steep hills can be very difficult for trucks to climb and dangerous when going downhill.
Geology identifies land made of clay. Clay is a natural geological road hazard because this type of land is often low, flat and wet. Low, wet ground is bad for winter roads because the mineral soil soaks up water like a sponge. Clay is not strong and changes quickly from a solid ice road to a soft, soggy, unstable road with deep ruts during freeze-thaw cycles. The many rolling bumps could damage vehicles. Landslides could occur and the area could flood.
Those conditions would shorten the life and usefulness of the winter road. Trucks would have to travel more slowly with reduced weight loads.
Geology shows areas where the earth broke a long time ago to create a fault line in the rock.
These fault areas may create long, narrow depressions in the earth where creeks, narrow lakes, and thick, wet, unstable soil may occur. Parts of a winter road that cross this type of area will likely require more maintenance.
Geology shows areas that are covered by thick muskeg, and have many lakes and creeks. Many winter road systems cross muskeg and lakes because it is possible to build long, straight stretches that don’t require tree cutting. Winter roads on this material are easier to maintain so long as the temperature remains cold. But the climate has been changing. Muskeg and lakes are becoming less dependable for a winter road.
The land between Fort Severn and Weenusk contains permafrost. Patches of permafrost occur north of a line from Sandy Lake, just north of Lansdowne House, to just south of Moosonee.
Building any stable road on permafrost is not easy. Anything that causes the permafrost to melt will cause the ice-rich soil to turn into mud. Mud is weak and when it freezes, it forms lumpy ground and damages the road. Geology helps identify areas where permafrost occurs. It tells us what mineral soil may be needed to cover roadsides to preserve the permafrost and lessen the chance of landslides.
It helps us solve technical problems such as what soil must be removed to make a stable road bed, what gravel is best for construction or which materials would insulate streambeds and culverts best. Often this is information used when constructing all-season roads, but it can also be a factor in the construction of a new winter road alignment.
Climate Change
Changes are taking place to the climate and Aboriginal Elders say the temperature is not as cold as it was when they were children.
The winter is not as long and blue ice is thinner than it used to be. The muskeg does not freeze like it used to and the permafrost is melting. The snow is different and the winter season is shorter. These are important changes — changes that affect the life of winter roads.
At least five of the past 10 years have suffered from a less reliable winter road season.
Climate change is causing many to re-think decisions to build winter roads on lakes, muskeg and poor geological soils. Geology has to be considered for future winter and all-season roads.
Role of Modern Geology
The Ontario Geological Survey (OGS) carries out modern geological mapping across Ontario, including the Far North.
The geology mapping methods include: geological field work to identify rock, sand, gravel, and clay deposits; geology land forms like eskers; and natural geological hazards like faults and landslide areas. The geology study includes: review of all public geologic maps and reports; environmental reports; photographs taken from aircraft and satellites; elevation and topographic maps; and the digging of pits or drilling of shallow holes to sample the earth and rock materials. Sometimes surveys, called geophysical surveys, are carried out using instruments on the ground or from aircraft to help describe the geology below the surface.
The results of the OGS studies are published as geological maps and in reports available to the public. This information is available at no cost, both online and in regional offices of the OGS. These maps and reports are used by First Nations and tribal councils, consulting companies working for First Nations, land-use planners, and engineers considering winter road realignment or all-season road options.
Without this modern information, it is difficult to plan and build new legs of winter roads, all-season roads, or winter road re-alignments. Disregarding the geology of a winter, or all-season road corridor will result in higher construction and maintenance costs and may cost more money in the long run, especially if the road is abandoned. Understanding the Ontario beneath our feet is important, especially as we adjust to climate change.