Young-Rainey STAR Centre Ross Towler & Robert Leather

Introduction Site Description Contaminants Alternative Remediation Techniques Remediation Adopted Conclusion

Site Description Location History Environmental Restoration Pinellas County, Largo, Florida History Formerly US DoE nuclear weapons research and development centre End of the Cold War; stewardship and maintenance of the nation’s nuclear weapons 1999; Young-Rainey Science Technology and Research (STAR) Centre houses more than 20 businesses that range from administrative to light manufacturing Environmental Restoration Full cleanup of soil and groundwater contamination

Contaminants Non-aqueous phase liquid (NAPL) Trichloroethene (TCE) 360 mg/l Dichloroethene (DCE) 450 mg/l Volatile organic compounds (VOCs) Vinyl chloride Methylene chloride Toluene Petroleum Hydrocarbons Area 10,000 sq ft, 35 ft Volume of 13,000 cubic yards

Alternative Remediation Techniques In-situ Remediation Techniques Soil treatment without excavation and transportation Cost savings Longer time periods Non-uniformity of treatment Less certain results Ex-situ Remediation Techniques Contaminant treatment after excavation of soil Shorter time period Uniformity of treatment Greater costs Engineering Problems associated with excavation

Biological Remediation Processes What is it? Stimulation of micro organisms Contaminant used as food source & broken down Contaminant destroyed or transformed Organic contaminants only Low cost Why not for YRSC? Contaminant concentration too high (Initially) However… reduced current levels make Bioremediation a viable option.

Physical/Chemical Treatment Physical/Chemical treatment uses the physical properties of the contaminants or the contaminated medium to destroy (i.e., chemically convert), separate, or contain the contamination. Examples… Chemical Oxidation Electrokinetic Remediation Soil Flushing Solidification/Stabilisation Soil Vapour Extraction

Containment & Offsite Disposal Migration of contaminant in soils/ground water prevented or significantly reduced Used in absence of realistic treatment option Does not lessen toxicity, mobility or volume of contaminant Offsite Disposal Contaminated material removed & transported to permitted off-site treatment and/or disposal facilities. Pretreatment usually is required Costly Disposal facilities uncommon Engineering problems associated with excavation

In Situ Thermal Treatment Techniques Steam/hot air injection, electrical resistance or other means used to increase the volatilisation rate of semi-volatiles and facilitate extraction Quick cleanup times, but generally costly Thermally enhanced SVE uses temperature to increase the volatility of the contaminants in the soils Similar to standard SVE , but requires heat resistant extraction wells.

Remediation Adopted Soil Media In-situ thermal enhanced soil vapour extraction technique Steam Enhanced Extraction and Electro-Thermal Dynamic Stripping Process (ET-DSP™) Steam injection wells Extraction wells ET-DSP™ electrodes

Remediation Adopted (2) Preheat the perimeter of the remediation area Steam injection was used to form a steam barrier around the perimeter Evacuation of vapourised effluents from the system Treatment included heat exchange, separations, and carbon adsorption Why this technique? Low permeability sediments Presence of TCE, NAPL etc.

Conclusion Goals Results Costs Soil cleanup; TCE – 20.4 mg/kg Groundwater cleanup; DCE – 50 mg/L Results After 4.5 months of operation all soil and groundwater cleanup goals had been met Costs total project subcontract cost was approximately $3,800,000