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SAND No. 2010-3070 C Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
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1. History and Types of Hazardous Waste Sites2. Discussion about Past Practices3. Remediation Technologies
• Containment Grout curtains, slurry walls, capping Monitoring
• Source Control (Soils, Sediments, Sludges) Pump and treat, Air/steam stripping, soil vapor
extraction Soil washing, solidification, mobile incineration
• Groundwater Treatment Carbon adsorption, bioremediation
Remediation of Hazardous Waste In-situ and Ex-situ Processes
SAND No. 2010-3070 C Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
The Late 20th Century Became a Time to Focus on Man Made Pollution
SAND No. 2010-3070 C Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
• Mining• Acid mine drainage• Heavy metals – Hg, Cr, Pb
• Industrial / Commercial Pollution• Dyes and pigments• Petroleum / gasoline
• Agricultural runoff • Pesticides• Nutrients – nitrates, phosphates• Salinization – Sodium, chloride
• Sewage• Pathogens - Enteric• Nutrients – Nitrates, phosphates• Contaminated animal feed
Surface and Groundwater Contamination Leads to Health Problems, Water Shortage
Textile Waste
Mining Waste
Gasoline
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In 1962, renowned author and naturalist, Rachel Carson, warned growing contamination “great underground seas” (i.e., groundwater) in “Silent Spring.”
Love Canal – New York, USA. Buried barrels of chemicals underneath new housing development (1950s). Became main cause for the Superfund legislation. Removed from Superfund in 2004.
Valley of the Drums – Kentucky, USA, 23 acre site with a large number of leaking drums. Fire at site in 1966. Not completely cleaned up until 1990.
Times Beach – Missouri, USA community where contaminated oil was used for dust control from 1972-1975.
The History of Hazardous Waste Pollution
SAND No. 2010-3070 C Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
Solid Waste can Directly Impact Human Health
• Solvents – Gasoline, diesel, chlorinated
• Leachates – Acid waste, heavy metals
• Hazardous waste – Metals, paints, solvents, pesticides
• Leaking fuel tanks – Gasoline, diesel
• Refuse - Decaying animal and plant matter
SAND No. 2010-3070 C Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
PathogensBacteria – Enteric, fecalProtists – Cysts and sporesVirus - Enteric
MetalsCopperLeadArsenic
Disinfection byproductsTrihalomethane - CHCl3,,CH2Cl2, CH2ClBrHaloacetic acid – CH2ClCO2H
Pesticides
Drinking Water, Wastewater Contaminants Directly Affect Public Health
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The larger the scope of contamination, the more limited the cleanup options.
After the pollutant has dispersed the groundwater may be undrinkable for years
Liability and funding for remediation may be quite expensive
General Lessons Learned in Remediating Hazardous Waste Sites
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Cleanup is much more costly and time consuming than properly managing wastes in the first place.◦ Treatment and excavation costs◦ Continuous expense for monitoring
Landfills, lagoons, piles and land spreading will often create large areas of contamination
Chlorinated solvents are often high density and thus will “sink” toward groundwater. (DNAPL)
More Lessons Learned
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Containment: Seals off all possible exposure pathways between a hazardous waste disposal site and environment.
◦ Slurry Walls◦ Grout curtains◦ Drainage systems◦ Capping◦ Monitoring
Remediation can Take Various Pathways
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Basic Grout Curtain Containment SystemSlurry Wall
Slurry Walls and Grout Curtains are Containment Technologies
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Slurry Wall
• Dig trench around an area
• Backfill trench with an impermeable material (clay) slurry
Containment Remediation- Slurry Wall Emplaces Impermeable Barrier
Cross Section of a Slurry Wall
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Slurry Walls can be placed in a circular fashion to divert groundwater around contaminant
Slurry Walls are Impermeable Barriers Made of Clay Materials
Plan View Slurry Wall
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Grouting
Inject liquid, slurry, or emulsion under pressure into the soil
Slury fills pore space Two types
◦ Particulate – solid + liquid solidifies◦ Chemical – Liquid +liquid that gels
Grouts are limited when high water table or rapid GW flow
Grout Curtains Injected in the Subsurface Solidification Reduces Permeability
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Downgradient Barrier and Extraction Wells (Top and Side Views) Upgradient Barrier and Extraction Wells
Containment Remediation Proceeds in Steps, Combined with Extraction
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All containment remedies are accompanied by an extensive groundwater monitoring.
Groundwater Monitoring is Necessary to Protect Drinking Water
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Principally used to remove or reduce hazardous waste contamination from the groundwater aquifer passing through or near the site.
Pump and Treat (including lowering of GW table) Steam Stripping Air Stripping Carbon Adsorption Bioremediation
Groundwater Remediation Reduces Spread of Contamination
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Soil Vapor Extraction (SVE)Air SpargingBioremediation (including Bioventing and Bioreactors)Air Stripping and Steam StrippingSoil Washing and Soil FlushingStabilization/SolidificationVitrificationThermal DesorptionMobile Incineration
Source Control Prevents Continued Release or Spread of Contaminants
Used to remove or reduce hazardous waste contamination from sludges and soils near the site.
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Steam StripperAir Stripper
Air and Steam Stripping for Source Control
These can be used in conjunction with Soil Vapor Extraction or Groundwater Treatment
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Fixed-bed Carbon Adsorption UnitCarbon Adsorption System
Carbon Adsorption - Water Treatment and Soil Vapor
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• Volatiles swept from groundwater
• Optional air sparge
Soil Vapor Extraction (SVE)
• Volatiles captured or treated at surface
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• SVE commonly enhanced with air sparging.
• Air sparging involves the active pumping of ambient air into the subsurface soil and groundwater to enhance the collection of volatiles through the SVE system.
Air Sparging Enhanced SVE
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• In-situ typically enhances naturally occurring biological activity• circulating nutrient and oxygen-enriched water-base solution• forced air movement provides oxygen to enhance naturally
occurring microbes.
• Bioventing has air flow rate lower than Soil Vapor Extraction (SVE) • deliver oxygen • minimizing volatilization.
• In-situ biological treatment is effective for non-halogenated volatiles and fuel hydrocarbons.
• Technology is less effective for non-biodegradable compounds and for soils with low permeability.
Bioremediation can Occur In-situ or Ex-situ
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• Use natural occurring and/or enhanced organisms
• Enhanced biotreatment involves add O2 and nutrients.
• Proper mixture of O2, nutrients and bacteria are site-specific and chemical-specific.
• Technique limited by pH, temp, toxicity of contaminants, and to aquifers with high permeability.
• Advantages:cost, minimal surface facilities minimal public exposure.
Biotreatment of Groundwater (In-situ)
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Ex Situ bioremediation involves excavating the contaminated soil
Placing it into biotreatment cells Adding nutrients to enhance biological activity Periodically turning it over to aerate the water. The moisture, heat, nutrients, oxygen, and pH
are usually controlled in the process. Separation of decontaminated solids
Bioremediation for Petroleum Waste (Ex-situ)
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A variety of bacteria and yeast have been successfully deployed in situ and ex situ biological treatment systems.
Bioremediation Organisms
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Soil Washing: Ex-situ
• Excavation• Wash soil with leaching agent or surfactant• Not effective with clay or high organic content
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Soil Flushing : In-situ
• Apply water solution to enhance contaminant mobility• Generated leachate intercepted• Especially good for halogenated and high permeability soil
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Solidification methods physically encapsulate hazardous waste into a solid material matrix of high structural integrity.
Stabilization techniques chemically treat hazardous waste by converting them into a less soluble, mobile or toxic form.
Principally used for metal-bearing wastes. Limited applicability to organic wastes. Typically used to concentrate contaminants prior to S/S. 2 Main types of processes: cement and pozzolanic.
Solidification – Stabilization (S/S)
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Description◦ Slurry of wastes and water is mixed with portland
cement to form a solid. Advantages
◦ Low cost ◦ Readily available mixing equipment ◦ Relatively simple process ◦ Suitable for use with metals
Disadvantages◦ Solids are suspended, not chemically bound
subject to leaching ◦ Doubles waste volume ◦ Requires secondary containment ◦ Incompatible with many wastes
Organics, some sodium salts, silts, clays, and coal or lignite.
Cement Stabilization (Ex-situ)
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Description◦ Waste is chemically reacted with lime and a fine-
grained siliceous material (fly ash, ground blast furnace slag, cement kiln dust) to form a solid.
Advantages◦ Low costs; ◦ Readily available mixing equipment; ◦ Suitable for power-plant wastes (FGD sludges, etc.) as
well as a wide range of industrial wastes, including metals, waste oil, and solvents
Disadvantages◦ Increases waste volume ◦ May be subject to leaching ◦ Requires secondary containment.
Pozzolanic Processes (Ex-situ)
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Thermal process converts contaminated soil to chemically inert stable glass/crystalline product.
Electrical current produces heat –melts soil Molten zone grows destroying/encapsulating hazardous constituents
and metals Hood for volatile emissions
In-situ Vitrification Process - Specialized S/S
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• Involves a wide variety of units such as small liquid waste incinerators at right.
• Multiple trailer rotary kiln for complex sludges and drummed waste, below.
• Infrared (electrically heated) “soil roaster” are also used. Infrared is a form of indirect heating using electric current instead of fuel oil to generate heat.
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31 years experience evaluating technologies and developing preventive policies for HW management
Developed key provisions of the U.S. statute governing daily waste management; The Resource Conservation and Recovery Act (RCRA)
Participated in enactment of the “Superfund” cleanup law. RCRA is intended to prevent the creation of additional “Superfund” or leaking waste sites
Worked with over 200 companies in evaluating waste treatment technologies and policies
Authored a text on major reforms to RCRA.
Acknowledgement and Background
Richard Fortuna, President, Strategic Environmental Analysis, L.C.
www.richardfortuna.com
SEA.LLC@richardfortuna.com