LNAPL Management Framework 5 Wing Goose Bay: Case Study 5 Wing Goose Bay Remediation Project Tom MacNeil, P. Eng., AMEC Environment & Infrastructure

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Background – History

§ History of 5 Wing Goose Bay § 5 Wing Goose Bay was

founded in 1941 - still active § Re-fuelling trans-Atlantic

flights § 6 tank farms – 2 active § 50 plus ASTs with capacity in

excess of 300 M litres § Dozens of former USTs § 160 km of pipelines

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Site of Interest – Heavy Bomber Hydrant Area

§  Land Use – airport apron, green space § Water table – 15+ m below ground surface § Unconfined sand aquifer § Apparent LNAPL Thickness up to 3 m, Jet Fuel §  LNAPL present currently as 2 discrete plumes § History of spills unknown but occurred decades ago § Active remediation ongoing since fall 2012 – 3 MPVE systems, 75

recovery wells

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Site of Interest – Heavy Bomber Hydrant Area

§  )

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LNAPL Management Framework

§ Phase 1 – Identify goals § Phase 2 – Data collection § Phase 3 – Data analysis § Phase 4 – Implementation § Phase 5 – Reporting & closure

§  Iterative process

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LNAPL Management Framework – Identify Goals (Phase 1)

§ GBRP Objective § “to remediate or risk manage legacy impacts in a way that

appropriately reduces the risk to human and/or environmental health to acceptable levels”

§ Actual / potential pathways § Direct – none (LNAPL at depth, no potable water usage) § Indirect – maybe (LNAPL or dissolved plume stability)

§  Is action necessary? § Yes

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LNAPL Management Framework – Data Collection (Phase 2)

§ Data Collection § Soil/Groundwater Investigations – 75+ MW’s § LNAPL Gauging – 3 years; quarterly to date § Dissolved Phase Monitoring - 3 quarters at 55+ locations § LNAPL Mobility Assessment § Groundwater Flow and Transport Modeling (basewide) § 2 LIF Investigations § 1 MIP Investigation

§  Identify data gaps – above investigations taken place over past 8 years

§ Data has been assembled into LCSM

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LNAPL Management Framework – Data Collection (Phase 2)

§  Lines of Evidence § LNAPL Mobility/Recoverability § LNAPL Transmissivity § LNAPL Plume Stability § Dissolved Plume Stability § Monitored Natural Attenuation Capacity

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LNAPL Management Framework – Data Analysis / Lines of Evidence (Phase 3)

§  LNAPL Mobility/Recoverability – MPVE recovery in decline, still variable with water table elevation

§  LNAPL Transmissivity – individual wells are above and below de minimus threshold for mobility

§  LNAPL Plume Stability – plume footprint appears stable § Dissolved Plume Stability – plume appears stable, limited data

at this point § Natural Attenuation – documented to be occurring on the site

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LNAPL Management Framework – Implementation (Phase 4)

§  Implementation § Operate 3 MPVE Systems through 2 more seasonal GW lows § Data Collection

–  MPVE system recovery –  LNAPL Monitoring – Stable?? –  Dissolved Phase – Stable?? –  LIF Investigations –  LNAPL Transmissivity – meets de minimus criteria?? –  MNA – document site capabilities –  Minimum of 8 quarters following system shutdown

§  Long Term Monitoring § Less intensive than Closure Monitoring § Confirm closure conditions are maintained

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LNAPL Management Framework – Reporting & Closure (Phase 5)

§ Update LCSM § Net Benefits – Key Considerations

§ Impossible to recover all LNAPL § Removal of all recoverable LNAPL predicted to take up to 9

additional years of MPVE system operation § No “walk away solution” § Energy use of remedy § Transfer of contaminant from one media to another § What is cost of recovery?

§ Reduce risk to acceptable level – Goal of GBRP § Can only remediate to current or intended federal use

§ Closure – present all material relevant material in overall site context

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Conclusion

Questions???