A slope at St. James Cemetery in Toronto is eroding, sparking a $2.5 million project to save cremated human remains of hundreds of people from sliding into the valley.

St. James Cathedral has embarked on a plan to stabilize the slope on the south side of the Rosedale Valley.

“Many of the lots were located close to the slope. People like that, it’s picturesque. But those locations can be compromised by Mother Nature,” said John O’Brien, the director of operations for St. James Cemetery.

He said crews had identified and mapped each of some 500 plots and identified which ones needed to be moved.

“Each was disinterred by hand. They were hand-dug. They were placed into separate containers, and all of those containers were placed in a larger secure container where they will remain until the work is finished,” O’Brien said.

Tens of thousands of people are interred at St. James Cemetery, the oldest still functioning cemetery in Toronto. The graves on this slope were placed between 1960 and 2010.

One of the reasons the slope is disintegrating is because of the Norway Maples, which were planted in the 1960s. They grow faster than native trees and their broad leaves create a thick canopy that crowds out native vegetation with deeper root structures that would have kept the soil more stable.

Some of those trees are being removed as part of the project, O’Brien said. Crews are also placing an interlocking series of piles under the ground that can act as a support structure for the escarpment, as well as adding drainage.

Finding relatives of everyone affected has been a challenge. The cemetery hopes that the publicity will help. O'Brien said they believe this is the largest disinterment in Ontario's history.

He says the cathedral is paying the $2.5 million tab.

“They are the owners of the Cemetery. They have an obligation to maintain these graves in perpetuity,” he said.

“The thought is at the end of it, it will be secure for generations to come,” he said.