Movement of Oil and Petroleum Products in Permafrost Impacted Soils

David L. Barnes, Ph.D., P.E. University of Alaska Fairbanks Water and Environmental Research Center

Students, Co-Authors, Collaborators

Dr. Kevin Biggar Dr. Evgeny Chuvilin Dr. Walter Fourie Dr. Yuri Shur Dr. Ian Snape Dr. Dan White

Hrishikesh Adhikari Karin Johansson Shawna Laderach Ekaterina Matveeva Stina Stjärnström Sarah Wolfe

University of Alaska Fairbanks Water and Environmental Research Center

Outline 1. Review of LNAPL migration fundamentals 2. Field studies conducted by Mackay et al. 1974 and Johnson et al.

1980 3. Impacts of pore-ice on LNAPL distribution 4. LNAPL distribution in suprapermafrost ground water 5. Influence of freeze and thaw cycling on LNAPL migration

University of Alaska Fairbanks Water and Environmental Research Center

Storage Tank

Vadose Zone

Capillary Fringe

Saturated Zone

Water Table

Dissolved Phase Plume

Fundamental Principles of LNAPL Migration

University of Alaska Fairbanks Water and Environmental Research Center

Saturated Zone

Water Table

Tank

Permafrost

Infiltration of LNAPL into the Subsurface in Continuous Permafrost Regions

University of Alaska Fairbanks Water and Environmental Research Center

Moss

Organics

Mineral

Permafrost

Past Field Studies

Mackay, D., Charles, M.E., and Phillips, C.R. 1974 and 1975. The Physical Aspects of Crude Oil Spills In Northern Terrain. 1st, 2nd and final reports. Task Force on Northern Oil Development, Environmental – Social Committee.

University of Alaska Fairbanks Water and Environmental Research Center

Summer

Extent of Oil Migration with Time Results from Johnson et al., 1980

Winter

Migration extent in one day

University of Alaska Fairbanks Water and Environmental Research Center

Surface Subsurface

Oiled Areas

Oil on Surface versus Subsurface. Results from Johnson et al., 1980

Summer

Winter

University of Alaska Fairbanks Water and Environmental Research Center

Major Finding from Summer Release Field Studies

• Both Mackay et al. and Johnson et al. showed oil released in the summer primarly flowed through an organic layer that overlaid water saturated mineral soils.

• Mackay et al. noted that in tests on summer releases in tundra soils, oil penetrated through the organic layer and flowed down gradient through very permeable soils directly above the frost line.

• The release by Johnson et al. still showed downslope migration 15 years after the release (Collins et al, 1994).

• Infiltration of oil into the mineral soil layer was observed by Johnson et al. in areas of relatively large oil volume accumulation.

University of Alaska Fairbanks Water and Environmental Research Center

Major Finding from Winter Release Field Studies

• Minimal penetration of oil below the top moss layer. • Increased viscosity of oil limited downslope migration. • Migration recommenced in summer.

University of Alaska Fairbanks Water and Environmental Research Center

11

Infiltration in Coarse Grain Soils 2-D Lab Studies

Purpose Determine qualitatively the influence of pore ice on the movement of petroleum hydrocarbons through soil.

University of Alaska Fairbanks Water and Environmental Research Center

Infiltration of JP 2 into Homogenous Medium Grain Sand One Minute After Introduction into Flume

26% Ice Saturation 54% Ice Saturation

University of Alaska Fairbanks Water and Environmental Research Center

26% Ice Saturation 54% Ice Saturation

Infiltration of JP 2 into Homogenous Medium Grain Sand 24 Hours After Introduction into Flume

University of Alaska Fairbanks Water and Environmental Research Center

(a) (b)(a) (b)

Preferential Flow Paths – Pore Scale

University of Alaska Fairbanks Water and Environmental Research Center

Pore Ice

Soil Grain

Air Void

Pore Ice

Soil Grain

Air Void

X-Ray CT Evidence of Blocked Pore Space Formation

University of Alaska Fairbanks Water and Environmental Research Center

Medium Sand

Medium Sand

Fine Sand

Petroleum Migration Through Layered Soils

University of Alaska Fairbanks Water and Environmental Research Center

Saturated Zone

Water Table

Tank

Permafrost

Infiltration into Suprapermafrost Ground Water Characterized by Small Saturated Depths

University of Alaska Fairbanks Water and Environmental Research Center

Petroleum Saturation in Shallow Aquifers

Tob

D

Pad pore water table prior to petroleum release

ground surfacemonitoring well

top of permafrost

Z=0

Tob

D

Pad pore water table prior to petroleum release

ground surfacemonitoring well

top of permafrost

Z=0

University of Alaska Fairbanks Water and Environmental Research Center

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Petroleum Saturation

Elev

atio

n fr

om P

erm

afro

st T

able

(m)

Petroleum Saturation as a Function of Saturated Zone Thickness

Oil-water interface exists

Saturated thickness = 0.4m

Saturated thickness = 0.1m

Elev

atio

n fr

om To

p of

Per

maf

rost

(m)

Petroleum Saturation

University of Alaska Fairbanks Water and Environmental Research Center

Saturated Thickness (m)

Petr

oleu

m V

olum

e (m

)

LNAPL thickness measured in well = 0.5m

LNAPL thickness measured in well = 0.7m

LNAPL thickness measured in well = 1.0m

Petroleum Volume as a Function of Saturated Thickness

University of Alaska Fairbanks Water and Environmental Research Center

Displacement of Petroleum

0 2 4 6 8Oil Content (%)

1614121086420

Dep

th (c

m)

Freezing Front

Initial Oil Content

Reproduced from Chuvilin et al., 2001

University of Alaska Fairbanks Water and Environmental Research Center

Conclusions

1. Fine grain soils and high water saturations control migration during thawed months.

2. Presence of pore-ice can result in the creation of preferential flow paths resulting in wider lateral petroleum distributions than may be expected.

3. Preferential flow paths in frozen soil may result in LNAPL migrating into permafrost.

4. Freeze and thaw cycling can remobilize petroleum.

5. Shallow nature of the active layer and thin saturated zone impacts vertical distribution of petroleum and subsequent dissolved phase plume

University of Alaska Fairbanks Water and Environmental Research Center

Funding Sources

University of Alaska Fairbanks Water and Environmental Research Center

Questions?

University of Alaska Fairbanks Water and Environmental Research Center

Petroleum Migration Through Frozen and Unfrozen Layered Soils

1 hour 1 day After Frozen Soil Thawed

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