Porcupine Gold Mines (PGM) has extensive mining-related land holdings in and around
the City of Timmins, Ontario. Many of these holdings consist of closed open pit and
underground mines and mine waste management facilities that are at various stages of
the closure and rehabilitation process. PGM is currently considering reclamation
options for several of its sites, and is going beyond the traditional options selection
process by utilizing quantitative Ecological and Human Health Risk Assessment
(EHHRA) to inform its reclamation choices as well as technical, financial and other
considerations. EcoMetrix Incorporated (EcoMetrix) is undertaking these analyses on
PGM’s behalf for its Aunor-Delnite, Pamour, and McIntyre and Coniaurum sites.
In general, risks from mine-related constituents in the environment are determined by
two components: exposure and toxicity. Both components must be present for an
environmental risk to exist. In this context, EHHRAs assess exposure and toxicity
separately and then combine the results of each assessment to characterize risks. In
this context, the risk characterization results are then used to prioritize source control
options at closure. Uncertainties and assumptions made are also analyzed and
evaluated in the EHHRA.