1 imagine the result 24 june 2015 © 2014 arcadis · 3 24 june 2015 © 2014 arcadis site...
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© 2014 ARCADIS 24 June 2015 1 Imagine the result
© 2014 ARCADIS 24 June 2015 2
Presentation Outline • Site Description and Background • Natural Environment • Objectives • Modified SLRA Approach • SLHHRA Highlights • SLERA Highlights • Innovative Approaches to Sampling • Value Added Approach to the Field Program • Next Steps
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Site Description and Background • 80 km decommissioned railway built in 1964 to allow
mining of ore near Fort Resolution, NT. • 1964 to early 1990s, ~ 60 million tonnes of ore and lead/
zinc concentrate were transported along the rail bed between Hay River and the open pit Pine Point Mine.
• The railway was decommissioned in 1996 with the removal of most infrastructure.
• Multiple communities are present in the regional area. • Current uses: uncontrolled borrow source, seasonal
camping and recreational activities (hunting, wild food foraging, ATVing, hiking, fishing).
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Pine Point Rail Bed, NT
• Site is a linear transport corridor surrounded by wild lands.
• Local area includes access roads to quarries near the rail bed, pit lakes, tailings piles associated with the former mining activities.
• Site is accessible by gravel access roads or from the adjacent highway.
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Site Description and Background • Historical assessment and closure
activities have primarily focused on the main mine footprint.
• Potential environmental impacts r e l a t e d t o a n c i l l a r y m i n e infrastructure (e.g., the transport of lead/zinc ore along the associated rail line) were not assessed at the time of mine closure.
• Remediation efforts focused on the former mine site and associated town site.
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Natural Environment
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• Shallow bedrock and pockets of coarse grained beach sediments.
• Naturally elevated regional soil concentrations of metals.
• Distinct characteristics of fenland habitats and mixed forests on low-lying poorly drained soils, and drier upland sites.
• Presence of federally listed, and culturally significant Species at Risk utilizing these habitats.
• Utilization of local foraged wild foods to supplement local people’s diets.
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Natural Environment
• Site crosses fish bearing rivers and creeks. • Importance of surface runoff as a transport
pathway to surrounding fen systems, local creeks and rivers.
• Local presence of regionally listed and culturally or commercially important fish species in rivers and streams which drain the Site.
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Objectives • Identify driving risks to human and ecological
receptors. • Scope future investigation for site areas and
media contaminants. • Obtain sufficient understanding of the
environmental and physical conditions at the site to make an informed decision on the necessity of any remedial or risk management actions.
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Modified SLRA Approach • Screening level risk assessment completed after the
Phase II Environmental Site Assessment (ESA) rather than after a Phase III ESA.
• Refined the SLRA approach to focus on site-specific receptors, realistic exposure terms, and refining exposure pathways with site specific data.
• Goal of the SLRA was to aid in scoping further site assessment and/or remedial and management actions by: • Identification of contaminants, media, and rail bed areas
driving unacceptable risks to human and ecological receptors.
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Modified SLRA Approach – Conceptual Site Model
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Screening Level HHRA Highlights • Local community members
(toddlers to adults) utilizing the local area for recreational activities.
• E.g. hunting, wild foods foraging, camping, ATVing.
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Screening Level HHRA Highlights • Exposure - seasonal and transient. • Considered a “worst case week” exposure to non-
carcinogens under an “ATV transport scenario” and a “camping scenario”.
• Considered seasonal and repeated access to the Site over a lifetime (multiple life stages) to evaluate potential risks to local community members from carcinogens.
• Potential health risks driven by exposure to lead and cadmium in foraged foods, and ingestion of lead in soils in assumed play areas, and lead in fugitive dust.
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Screening Level ERA Highlights • Terrestrial and aquatic plant and
invertebrate communities • “At risk” and typical birds,
mammals and fish
• Exposure pathways included – direct contact with media, as well as accumulation of metals in tissues (invertebrate and vegetation) representing food items for larger wildlife receptors.
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Screening Level ERA Highlights • Various information sources were considered in the SLERA
• Risk calculations based on chemistry data • Presence/absence biological observations • Sediment toxicity testing at Site and reference locations.
• Plant and invertebrate community receptors unlikely to be affected by railbed soil metals given negligible habitat on the ballast and acceptable risks adjacent to the ballast.
• Potential adverse effects to typical (e.g. shrew, grouse) and at risk (e.g. common nighthawk) terrestrial receptors with small home ranges, driven by ingestion of soil metals.
• Potential localized adverse effects to benthic invertebrates and plant communities in discrete creosote treated abutement areas.
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Innovative Approaches • Northern climate - dry, windy • ATV- typical means of transport
in northern remote areas. • Ballast material – negligible
organic material, and lead/zinc concentrate powder f rom historical transport in unlined rail cars.
• Conducted site specific fugitive dust sampling during ATV transit along the railbed, using a SKC aluminum cyclone, filter cassette and pump system.
• Collected site specific particulate concentrations (kg particulate/m3) and reported metals concentrations (mg contaminant/m3) in respirable dust (<10 µm).
• Maximum measured concentrations were utilized in ATV user quantitative risk calculations.
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“Value Added” Approach to Field Program • L i n e o f E v i d e n c e - B i o l o g i c a l
observations in terrestrial and aquatic habitats (e.g. rapid benthic invertebrate assessment protocol).
• Line of Evidence - Conducted sediment toxicity tests
• Conducted surveys with local residents and aboriginal people regarding site specific land uses, exposure durations and foraged food intakes.
• Conducted vegetation sampling of targeted wild foods, as well as “forage and browse” species in co-ordination with surface soil sampling.
• .
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Next Steps Modified SLRA approach supported and focused future assessment work to: • Further assess contaminants (e.g. lead) and
media (e.g. soil, foraged foods, sediment) driving unacceptable risks to site-specific receptors.
• Focus future assessment work, in some cases, to localized Site areas (e.g. abutments).
• Refine the conceptual model exposure pathways (e.g. foraged food intake) for human and ecological receptors.
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Acknowledgments • Project work was conducted for:
• Project work was executed in collaboration with Columbia Environmental Consulting Ltd.
• Key Staff: Susan Winch, Meagan Gourley, Charlotte Lessard, Barbara Hard, Steve Livingstone (Franz/ARCADIS), Summer Zawacky and Elliot Tonasket (Columbia)
• Local knowledge contributed by: Mr. Arthur Beck (Fort Resolution Metis Council) and Mr. Al Browning (Hay River Metis Council).
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Imagine the result
Thank you! Questions?