Preliminary Site Investigations of Orphaned Mine Sites
The BC Ministry of Agriculture and Lands came to Hemmera with the need to evaluate the environmental risk at the sites of five historic “orphaned” mines in northern BC: the Stemwinder Mine, the Larrabee Mine, the Morning Star Mine, the Fairview Mine and the Dividend-Lakeview Mine. In each mine site, Hemmera teams performed Phase 1 and Phase 2 Preliminary Site Investigations.
In the Stage 1 phase, desktop reviews of literature and information identified areas of potential environmental concern. Further investigative work included site reconnaissance, geochemical assessment, acid rock drainage, metal leaching, and ecological surveys to identify sensitive species. We managed the review of information, which involved geology, hydrogeology, aerial (by helicopter) and ground site reconnaissance, assessment of wildlife and sensitive habitat areas, and evaluation of applicable assessment criteria.
The limited Stage 2 phase included collection of waste rock, surface water, adit discharge water and surficial soil samples, geochemical assessments of the samples, a non-intrusive preliminary evaluation of mining-related contaminant sources and pathways, and field surveys of habitat, human land use, and threatened and endangered species.
For each mine site, we also completed a Preliminary Risk Assessment, using site-specific conceptual models to characterize the sources, pathways, and receptors. These studies involved field investigation and sampling, the identification of risks and exposure units, and the development of a conceptual model for each exposure unit.
To help the client in future decision-making, the sites were then ranked for environmental risk, to determine the highest priorities for restoration activities.