Calcium treatment of gravel roads is done strictly for the purpose of dust control. Generally, the dust control program commences after half load restrictions have been lifted (this typically occurs after the first week of June). This is partly because the roads are already damp (as the frost comes out of the ground) in the spring and therefore does not generate significant dust concerns. Roads are also susceptible to deformation by heavy traffic loading during this damp period in the spring and this treatment is largely applied via large tanker trucks.
Calcium is applied to gravel roads only on an as and when needed basis and is largely weather dependent (i.e. dust suppression may not be required during a damp summer). However, not all gravel roads receive calcium treatment. When required, calcium is applied in the form of liquid via large tanker trucks or in the form of flakes (solid) which are placed manually by City crews in harder to reach areas. The gravel is typically graded and/or patched as necessary prior to the application of a calcium treatment. A calcium treatment may last between 2 to 3 months depending on weather and traffic volumes.