Closure and reclamation of the Bouchard-Hébert mine site, Rouyn-Noranda, Québec, Canada
Bibliographic record
Abstract
The Bouchard-Hébert mine is a closed zinc operation located approximately 30 km northeast of the city of Rouyn-Noranda in the Abitibi region of Québec, Canada. The mine operated from 1987 to 2002 and was closed in 2005. In 2021 approximately 50,000 m3 of potentially acid generating (PAG) waste rock was relocated to the permanently flooded portion of the nearby open pit. This was done to both improve site aesthetics and reduce contaminant loads to groundwater downgradient and the site’s water treatment system. The waste rock is partially oxidised and has generated substantial acidity and metal-laden seepage due to acid rock drainage/metal leaching (ARD/ML) since it was deposited. An additional 18,700 m3 of waste rock was relocated to the pit in 2023 as part of ongoing reclamation activities. Submerging PAG waste rock under water will eliminate future ARD/ML generation by these materials by preventing sulphide oxidation. This is best management practice for reactive, sulphide-bearing materials according to Mine Environment Neutral Drainage Program guidelines (MEND 2015) and other international guidelines, e.g. the Leading Practice Sustainable Development Program (LPSDP 2016). PAG waste rock relocated to the pit was amended with a neutralant (crushed limestone) to neutralise its existing acidity (titratable acidity plus jarosite acidity) content and thereby prevent the release of acidity and metals to groundwater once the waste rock is submerged. Waste rock that will not be submerged under water was amended with enough limestone to neutralise the total acidity content of the samples, i.e. acid generating potential and existing acidity. This paper describes how dosing rates were estimated and the process of mixing waste rock and limestone during relocation to the pit. The findings from recent sampling of the waste rock relocated in 2021 confirm that the jarosite in waste rock has decomposed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.005 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".