Soil Contamination- Overview and Case Study

Soil ContaminationOverview and Case Study Christopher Lyles ESS 315 How soil becomes Contaminated Urban runoff

Agricultural runoff Mining Industrial Operations Atmospheric Deposition Contaminated Groundwater

Sources of Contamination Gas Works Park 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 Borehole and Well SitesContour Map Water Table Contour Map and Flow Paths Geologic Cross Sections

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

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 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 Air Sparging/ Soil Vapor Extraction (AS/SVE)

Phytoremediation References http://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