Soil Contamination- Overview and Case Study

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Soil Contamination- Overview and Case Study

• Christopher Lyles
• ESS 315

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How soil becomes Contaminated

• Urban runoff
• Agricultural runoff
• Mining
• Industrial Operations
• Atmospheric Deposition
• Contaminated Groundwater

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Sources of Contamination
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Gas Works Park
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Gas Works Park
Previous site of coal and oil gasification (1900
to 1956) Waste accmulations include coal, tar,
and oil Polynuclear aromatic hydrocarbons (PAHs
)and volatile organic compounds (VOCs) are
present in groundwater PCBs, heavy metals, and
cyanides also present Gas Works deposit is as
thick as 9 feet across the park and overlies the
Vashon Till- consists of waste products from
prior operations ( Developed by Seattle Parks and
Recreation and subsequently studies by USGS and UW
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Borehole and Well Sites- Contour Map
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Water Table Contour Map and Flow Paths
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Geologic Cross Sections

• Important to understand the Gas Works Deposit
  as Its interaction with the Ground Water is the
  main concern

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Contamination processes

• Weathering of Hydrocarbons in soil and NAPLs
• Weathering- dissoultion, volatilization,
  biodegradation
• These processes release water-soluble, low
  molecular weight orgainc compunds into water,
  leaving behind stained soils containing
  insoluble, high molecular weight compounds

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Not Quite Polluted Enough
to become a superfund site (in 1980) But
polluted enough to cost tens of millions of
dollars to clean up Puget Sound Energy and City
of Seattle still continuing to monitor and clean
the site
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Main Concerns/ Remediation Techniques

• Benzene (toxic/ Carcinogenic)
• Naphthalene (Toxic/ non-carcinogenic)
• PAHs (vary depending on type but can be both
  Toxic and Carcinogenic)

• Air sparging/ Soil Vapor Extraction (AS/SVE)
• Monitored Natural Attenuation (possible
  phyto-remediation to be used in future)
• Direct Soil contact Remedy

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Air Sparging
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Air Sparging/ Soil Vapor Extraction (AS/SVE)
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Phytoremediation
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References
http//www.ecy.wa.gov/programs/tcp/sites/gaswkspk/
Gas20Works20Agreed20Order20DE202008.pdf http
//www.seattlepi.com/local/331605_gasworks14.html h
ttps//info.ngwa.org/GWOL/pdf/901878014.PDF http/
/www.ecy.wa.gov/pubs/0709080.pdf http//www.epa.go
v/superfund/about.htm http//www.ecy.wa.gov/progra
ms/TCP/sites/gaswkspk/gaswks.htm http//www.ecy.wa
.gov/programs/tcp/sites/gaswkspk/Five20Year20Rev
iew.pdf