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PFAS – Emerging Constituents of Concern for Mine Closure Studies

Abstract

In this presentation, a screening-level site investigation of per- and/or polyfluoroalkyl substances (PFAS) was conducted at six legacy mining sites in North America, ranging from 10 to 92 years of inactivity. Soil and water samples were collected based on historical infrastructure locations, current monitoring networks, hydrogeological conditions, and flow gradients. Groundwater, leach drain-down solutions, and pit lake water samples were collected, along with soil samples from various locations near mining facilities. These samples were tested for 36 PFAS compounds.

The screening revealed the presence of nine PFAS compounds at five of the six legacy sites. The results were compared to reference guidelines from various sources. This study aims to inform mine closure planning, expand groundwater monitoring, or establish continuous monitoring programs at select locations. It also provides baseline data for potential future PFAS regulations.

PFAS distribution according to mine facilities: solid samples

 

PFAS, a group of over 9000 chemicals, have been used in various industries since the 1930s. However, it gained attention for health risks in the early 2000s due to their persistence and bioaccumulative nature, leading to the dangers of the immune system, kidney, liver, and cancer. They are used in multiple industries, including mining, enhancing metal recovery, and as mist suppression agents. Assessing PFAS at North American mining sites is voluntary, as there are no regulatory drivers for PFAS standards enforcement at such facilities, posing challenges due to limited historical information about specific chemicals used in processing circuits.

 

Authors: 

Omar Felix | SRK Consulting, USA

Corolla Hoag | SRK Consulting, USA

Kartika Srivastava | University of Arizona

 

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