Laura Jones Golder Associates Ltd.

Using Laser Induced Fluorescence (LIF) to Establish Monitoring Well Network of Migrating LNAPL Plume in the Vicinity of Surface Water

www.vertexenvironmental.ca

SMART RemediationToronto, ON

January 29, 2015

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Using LIF to Establish Monitoring Well NetworkFormer Michigan Avenue LandfillFebruary 13, 2015

Presented By:Laura Jones, M.A.Sc., P.Eng.

Presentation Outline

Site History

Overview of LNAPL (oil) behaviour

LIF Background

LIF Investigation and Results

Current Monitoring Well Network

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Former Michigan Avenue Landfill

Historical Setting

Sarnia Observer, March 6, 1931

1952

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Extent of LNAPL – 1999 Lake Chipican

Inferred LNAPLExtent

Confirmed LNAPLExtent

Timeline

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LNAPL – Common Misconceptions

Misconception Conceptual Framework

LNAPL enters the pores as easily as groundwater.

Capillary pressures and multiphase flow (air, water, NAPL) affects migration

All the LNAPL is recoverable LNAPL is only recoverable when the LNAPL transmissivity is high enough

Pores in an LNAPL zone are at 100% saturation

LNAPL saturation function of soil type, generally less than 40%

LNAPL floats on the water table like a pancake

LNAPL is distributed like a shark fin with the highest saturation near water table

If LNAPL thickness increases, it means the LNAPL zone is advancing.

LNAPL thickness changes with water table fluctuations

LNAPL spreads in the direction of groundwater flow.

LNAPL spreads based on the LNAPLdriving head

LNAPL continues to migrate over long periods of time.

Due to capillary forces and reduced LNAPLdriving head, LNAPL migration generally ends a few years after a release

LNAPL Site Conditions

Inferred source area associated with oily clay-rich material in lowland swampy areas in northwestern portion of former landfill

Oil present since 1920s-1944 (at least 80 years old)

Migration beyond source area within fill material and native sand deposits

Limited potential for on-going migration unless significant hydraulic changes (e.g., historical low lake levels in Lake Huron)

LNAPL investigations/remedial actions have focused on leading edge

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Laser Induced Flouresence

LIF involves emitting a laser pulse via fiber optic line and subsequent capture of induced fluorescence via separate optic line to measure peak wavelength and intensity.

Molecules of hydrocarbons in the soil first absorb light – then fluoresce.

PAHs present in hydrocarbons facilitate NAPL identification.

Lighter compounds (e.g., gasoline) tend to fluoresce at shorter wavelengths vs. heavier compounds (e.g., motor oil).

shortUV

longUV

kero

sene

gaso

line

dies

el

oil

(Dakota Technologies)

Sample LIF Profiles

“Clean” “Motor Oil Impacted” “Diesel Impacted”

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Results of 2012/2013 LIF Investigations

2012 Investigation

2013 Investigation

Seasonal Water Body

LNAPL Discovered October 2012

LNAPL Discovered November 2013

Borehole and Well Installation November 2012

Ponds

2011 Sheet Pile

2012 Sheet-pile

Timeline – October 2011 to Present

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2014 LIF Investigation

Preliminary 3D Visualization

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Current Monitoring Well Network

Summary

LNAPL present from historical operation of a landfill and deposition of oily wastes from a refinery

LNAPL is migrating towards surface bodies in the vicinity of Lake Chipican (both permanent and seasonal)

LIF was used to establish the current foot print of LNAPL and establish a network of sentry wells

Sentry wells provide advanced warning of LNAPL migration to protect surface water

Traditional delineation methods would have used a larger grid size and could have missed narrow finger plume of LNAPL migrating northwards (less than 15 metres wide)

LIF investigation was used to develop remedial action plan prior to LNAPL migration to surface water with consultation with the client and the Ministry of the Environment and Climate Change

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Questions?

Lake Huron – Historical fluctuations