For those who may have heard of 200 graves outside a residential school in Canada.

Relax. Those are not graves. They are trenches dug 100 years ago to handle the sewage from the school. The ground penetrating radar picked up ground disturbance to a depth of 3-4 feet. Well the school had to get rid of its sewage somehow so it dug about 2000 feet of sewage trenches exactly where the 'graves' were discovered.