A century of contamination

Situated where the Canadian Shield intersects the Great Lakes lowlands, some 200 kilometres southwest of Ottawa and 65 kilometres east of Peterborough, the Deloro area is rich in mineral deposits. In 1866, gold was discovered - the name Deloro is based on the Spanish word for gold - and within five years, numerous shafts had been sunk and refining facilities had been constructed. The extraction of gold was no easy task. The gold-bearing ore was bound up with arsenic, a potentially dangerous byproduct.

The gold mines closed in the early 1900s and the site was used to process silver and cobalt ores from mines in northern Ontario. In the 1930s, 1940s and 1950s, smelted ore was brought from Eldorado Nuclear Limited in Port Hope for further refinement to extract the cobalt. Deloro was the first plant in the world to produce cobalt commercially and was also a leading producer of stellite, a cobalt-chromium-tungsten alloy highly valued during the war years. Ores from all over the world were processed in Deloro's smelter. Pesticides were produced from the arsenic byproducts of the smelting operations and continued as a major activity at the site until those products were replaced by organic pesticides in the late 1950s.

By the time the mining and refining operations were shut down, nearly a century's worth of hazardous byproducts and residues - a complex blend of toxic compounds, heavy metals and low level radioactive wastes - remained on the property. Early cleanup efforts also uncovered serious contamination of the site's soil, surface water and groundwater.

The Ministry Takes Control