Study will help Nanaimo better understand mine network

NANAIMO – The city will hire a team of consultants to map areas of the underground coal network at risk of subsidence.

A study of Nanaimo’s abandoned coal mines is a “baby step” toward understanding the stability of underground tunnels, according to the city’s acting manager of engineering.

Nanaimo city council unanimously agreed Monday to engage a team of consultants to map areas of the city’s abandoned mines that could collapse into sinkholes. The municipality will also ask the B.C. Ministry of Energy and Mines to partner on better understanding risks of underground tunnels by providing funding or access to technical experts.

The first phase of work, estimated to cost $50,000, has never been undertaken by the City of Nanaimo before, says Poul Rosen, the city’s acting manager of engineering. Consultants will look at all the mines honeycombed beneath the city and determine where there’s a potential for sinkholes to develop. The information is expected to help the city’s engineering department determine high priority areas for “subsidence risk,” whether or not there should be concern for utility work over some mines and identify areas Nanaimo city council could potentially do further fieldwork.

“This study is a first step in potentially what could be  a longer program,” he said.

The recent effort comes after the discovery of a two-storey deep mine collapse and developing sinkhole beneath Pine Street in south Nanaimo.

It was the first time city officials had encountered a mine that presented an immediate and serious safety issue, prompting plans to search for other dangerous and weakened tunnels.

The B.C. Ministry of Energy and Mines has indicated it would be willing to work with the city to determine the risk of abandoned mines but it’s not yet known what form the partnership will take, according to Rosen.

City staff members will now formally request the partnership and come up with terms of reference for consultants to develop a work plan.