Minister of the Environment
I am pleased to provide Environment Canada's response to your Environmental Petition no. 202, to the Interim Commissioner of the Environment and Sustainable Development, concerning environmental damage and remediation at the former federal DEVCO mine sites. Your petition was received in the Department on May 23.
The enclosed document contains the reply to question 8, pertaining to orange precipitate and acid mine drainage, which concerns Environment Canada.
I understand that the Minister of Fisheries and Oceans, the Honourable Loyola Hearn; the Minister of Natural Resources, the Honourable Gary Lunn; and the Minister of Public Works and Government Services, the Honourable Michael Fortier, will be responding separately to questions in your petition that relate to their respective mandates and regulatory responsibilities.
I appreciate this opportunity to respond to your petition, and I trust that you will find this information useful.
Environment Canada response to Environmental Petition no. 202, pursuant to section 22 of the Auditor General Act, regarding environmental damage and remediation at the former federal DEVCO mine sites
Question 8: What is the difference between what NSDEL says is "orange precipitate" and what everyone else says is typical "Acid Mine Drainage"? What is Environment Canada and DFO doing about the "orange precipitate" being discharged into a brook that flows into ocean fishing grounds at the mouth of the Bras d'Or Lakes?
Response: The International Network for Acid Prevention has produced a glossary of commonly used terms related to acid rock drainage (ARD). They define ARD as "low pH drainage derived from materials with an insufficient capacity to neutralize the acidic products of sulfide and elemental sulfur oxidation and the dissolution products of acidic minerals and amorphous materials. ARD is produced when the Neutralization Potential (NP) is no longer capable of maintaining neutral pH conditions in a measurable volume of drainage. In the context of mining, may be referred to as acid mine drainage (AMD)."
ARD is characterized by low pH and often high metal levels. The yellow/orange precipitate commonly associated with ARD occurs when the pH of the ARD discharge is subsequently raised to above 3 or 3.5 through either mixing with the receiving water and/or contact with minerals possessing the ability to neutralize acidity. This raise in pH levels leads some of the iron and other metal ions in the solution to precipitate in the form of metal hydroxides.
The discharge from the under-drain collection system associated with the settling pond on the former Cape Breton Development Corporation Prince property has a neutral pH and therefore cannot be referred to as ARD. It is, however, an iron-bearing, anoxic groundwater that gets oxygenated when discharged to the surface. As explained by the Nova Scotia Department of Environment and Labour, in their letter of March 14, 2007, this results in the oxidation of dissolved iron into ferric oxy-hydroxide, which then settles in the form of an orange precipitate (sometimes known as "ochre").
Subsection 36(3) of the Fisheries Act prohibits the deposit of deleterious substances into waters frequented by fish. The compliance status of the settling pond under-drain effluent is assessed by Environment Canada in accordance with the "Compliance and Enforcement Policy for the Habitat Protection and Pollution Prevention Provisions of the Fisheries Act." Standard 96-hour acute lethality tests were conducted on samples collected by Environment Canada at that location on November 30, 2006, and on June 12, 2007. On both occasions, the results did not provide evidence of a violation of subsection 36(3) of the Fisheries Act, as the samples were determined to be non-acutely lethal.