Introduction to the Soils and Sediment
Data Tables and Charts
Obed Mountain Mine Incident
This page provides additional information about the findings of independent experts regarding the contents of the soil and sediment from the breach of a water pond at the Obed Mountain Mine on October 31, 2013.
A key finding was that the composition of the sediment carried by the release into the Apetowun and Plante Creeks, and then into the Athabasca River, aligned with that of the natural soil in the mountainside around the mine area; and the vast majority of test results were well below Alberta’s most stringent guidelines for the protection of human and ecological health. Results that were above the guidelines occurred in both the natural soil and the sediment that had been released.
Links to data tables and charts detailing the soil and sediment test results are posted below.
Overview of Soil and Sediment Data Tables and Charts
- Surveyors collected samples of the deposited sediment and the natural soil in 24 locations along the Apetowun Creek and from the area around the mine on November 8 and 9, 2013.
- The soil samples came from undisturbed natural areas around the mine.
- The sediment samples came from material deposited by the water release.
- The source of the sediment may have been from the pond or soil eroded from the creek bank by the release.
- The tables are comprehensive, while the charts summarize key findings.
- The map shows the sample locations, which were named in two ways: one using the word “soil” followed by a number location, as in SOIL001, and the other using the convention ENV102L, which stands for environment, a number location and “L” for left side of the creek (others will have “R” for the right side).
Summary of Findings
- The charts show trace recordings for 37 constituents. The vast majority of the test readings are well below Alberta’s most stringent guideline, which is shown in the charts by a red dotted line. The standards are outlined in the government document Alberta Tier 1 Soil and Groundwater Remediation Guidelines.
- In the tests, which examined more than 2,700 indicators at the 24 sample locations, there were 15 recordings at or above guidelines and they occurred in both the natural soil and the sediment.
- The exceedances were for Fluoranthene, Naphthalene, Phenanthrene and Pryene. All are polycyclic aromatic hydrocarbons (PAHs), which typically occur as a result of combustion. While the source of these PAHs is unknown, they do occur in nature.
- What is evident in the soil charts is that the composition of the sediment carried by the water release aligns with the composition of the natural soil in the mountainside around the mine area.