GUELPH -- An archeological dig is underway in Guelph's downtown core as part of a series of steps that must be taken before a new library can be built.

The dig location on Baker Street is the same site where dozens of graves were previously found.

"It was a cemetery and then a park and several industrial buildings and curling rink," said Mike McCready with Archaeological Research Associates Ltd.

According to the City of Guelph, what is now the Baker Street parking lot was originally an all-faith public burial ground in the early 1800s.

The site was developed after being sold to the city.

In 2016, city crews came across human remains and coffin hardware. Years before that, sinkholes had revealed other graves in the area.

"They actually did the whole southern portion of this parking lot and uncovered I think it was 45 graves that were still present from the burial ground," McCready said.

In July, Guelph city council approved a redesign for the lot between Baker Street, Woolwich Street, Chapel Lane and Park Lane.

A 15-storey high rise for residential and commercial use will be built along with a new library branch.

"If everything goes well, and this is why we are starting the work now, we can have construction start in the spring or summer of next year," said Jayne Holmes with the City of Guelph's infrastructure, development and enterprise services.

Before any construction began, members of the Indigenous community held a smudging ceremony in the parking lot.

"The local First Nations are all being engaged," McCready said.

So far, only test areas of the concrete have been disturbed. The north section of the parking lot has never been searched for graves and it's uncertain if any will be found.

"We usually don't go deeper than two metres in these situations because that should get us down to native soil," McCready explained.

Any graves that are found will likely be transferred to Woodlawn Memorial Park.