Soil Contamination-

Overview and Case Study

Christopher LylesESS 315

Christopher LylesESS 315

How soil becomes Contaminated

How soil becomes Contaminated

Urban runoff Agricultural runoff Mining Industrial Operations Atmospheric

Deposition Contaminated

Groundwater

Urban runoff Agricultural runoff Mining Industrial Operations Atmospheric

Deposition Contaminated

Groundwater

Sources of ContaminationSources of Contamination

Gas Works ParkGas Works Park

Gas Works ParkGas Works ParkPrevious site of coal and oil gasification (1900 to 1956)

Waste accmulations include: coal, tar, and oil

Polynuclear aromatic hydrocarbons (PAH’s )and volatile organic compounds (VOC’s) are present in groundwater

PCB’s, 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

Borehole and Well Sites- Contour Map

Borehole and Well Sites- Contour Map

Water Table Contour Map and Flow Paths

Water Table Contour Map and Flow Paths

Geologic Cross SectionsGeologic Cross Sections

Important to understand the “Gas Works Deposit” as It’s interaction with the Ground Water is the main concern

Important to understand the “Gas Works Deposit” as It’s interaction with the Ground Water is the main concern

Contamination processesContamination processes

Weathering of Hydrocarbons in soil and NAPL’s

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

Weathering of Hydrocarbons in soil and NAPL’s

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

Not Quite Polluted Enough…

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

Main Concerns/ Remediation Techniques

Main Concerns/ Remediation Techniques

Benzene (toxic/ Carcinogenic)

Naphthalene (Toxic/ non-carcinogenic)

PAHs (vary depending on type but can be both Toxic and Carcinogenic)

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

Air sparging/ Soil Vapor Extraction (AS/SVE)

Monitored Natural Attenuation (possible phyto-remediation to be used in future)

Direct Soil contact Remedy

Air SpargingAir Sparging

Air Sparging/ Soil Vapor Extraction (AS/SVE)

Air Sparging/ Soil Vapor Extraction (AS/SVE)

PhytoremediationPhytoremediation

ReferencesReferenceshttp://www.ecy.wa.gov/programs/tcp/sites/gaswkspk/Gas%20Works%20Agreed%20Order%20DE%202008.pdf

http://www.seattlepi.com/local/331605_gasworks14.html

https://info.ngwa.org/GWOL/pdf/901878014.PDF

http://www.ecy.wa.gov/pubs/0709080.pdf

http://www.epa.gov/superfund/about.htm

http://www.ecy.wa.gov/programs/TCP/sites/gaswkspk/gaswks.htm

http://www.ecy.wa.gov/programs/tcp/sites/gaswkspk/Five%20Year%20Review.pdf