Thunder Bay Roads: What is a Sinkhole?

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Sinkhole on Ambrose Street
Sinkhole on Ambrose Street

THUNDER BAY – Over the course of this spring there have been a number of sinkholes opening up on Thunder Bay roads.

While the most notable is River Street just north of Algoma, there are a lot of places across the city where sinkholes have opened up either around drainage areas, or right in the roadways.

Julie Wiejak, a Policy and Research Analyst with Infrastructure and Operations with the COTB tells NetNewsLedger, “The overall higher influx of calls has contributed to delays in repair- some delays are due to being required to wait for water to recede, perform inspections to plan for the proper repair, and/or wait for locates to be in place”.

“There has been an increase this spring due to the high levels of water caused by the spring melt and rain events. Often, sinkholes are caused by a culvert that has failed or due to washouts from overland flooding-the water finds the path of least resistance and undermines the road causing a void,” adds Wiejak.

What is a sinkhole?

A sinkhole is a closed natural depression in the ground surface which is caused caused by removal of material usually by water flowing into the area under the ground and causing either the collapse or gradual subsidence of the surface into the sinkhole.

While a pothole is usually a fairly small feature caused by failure of paving materials, usually associated with roads, parking lots, and airports caused by freeze-thaw damage to roadways.

There is a section of Winnipeg Avenue just off Memorial which was paved within the last two years. That roadway has a sinkhole on one side along with a major depression forming right alongside Memorial Avenue.

There is another large sinkhole on Ambrose Street. As well there are almost countless numbers of sinkholes forming around sewer drains across the city.

What some construction experts are telling NetNewsLedger is that one of the issues appears to be that the road base isn’t being compacted sufficiently, and that there isn’t enough depth of asphalt being applied.

Some city councillors are telling NetNewsLedger that the infrastructure deficit of almost $20 million dollars a year, where the city has not been putting enough funds into our roads, bridges and sidewalks, is huge problem.