Web-­‐based  Class  Project  on  Geoenvironmental  Remedia7on  

Report  prepared  as  part  of  course    CEE  549:  Geoenvironmental  Engineering    

Winter  2013  Semester  Instructor:  Professor  Dimitrios  Zekkos  

Department  of  Civil  and  Environmental  Engineering    University  of  Michigan  

StabilizaAon  /  SolidificaAon  Prepared  by:  

 

   Lizzie  Grobbel   Zhijie  Wang  With  the  Support  of:    

Overview •  Introduction to S/S •  Theories, Advantages and Disadvantages •  Field Setup •  Technology Selection •  Important Considerations •  Treatment Costs •  QA/QC •  Case Studies

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S/S Introduction •  Stabilization ▫  Less hazardous and mobile form

•  Solidification ▫  Liquid or semisolids into solids

•  No removal or degradation ▫  Prevent contaminants transport by

reducing their mobility

•  BDAT for 57 types of hazardous wastes listed in RCRA

•  25% of Superfund site remediation

Sourse: www.wrscompass.com

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S/S Applicability •  Applicable to wide range of contaminants ▫  Metals (best) ▫  Radionuclides ▫  Inorganics ▫  Non- or semi- volatile organics ▫  But not good for volatile contaminants

USEPA, 1993

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Theoretical Background – Sorption

•  Use sorbents to eliminate free water or improve handling of liquid wastes by chemical bonding or physical forces

•  Sorbents ▫  Activated carbon, anhydrous sodium silicate, various forms of gypsum, celite, clays,

expanded mica, and zeolites •  Concerns ▫  Sufficient sorbents ▫  Compatibility

•  Limitations ▫  Leaching often happens – landfills

(Source: USEPA, 1986)

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•  USEPA (1997): “using inorganic reagents to react with certain waste or through the reaction among themselves to form chemically and mechanically stable solids”

•  Common reagents ▫  Portland cements, fly ash, lime and kiln dust, etc.

•  Advantages ▫  $$ ▫  Wide availability of reagents

•  Disadvantages ▫  pH value ▫  Incompatibility

Theoretical Background – Cementitious S/S

USEPA, 1997; Spence and Shi, 2004

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Theoretical Background - Polymer S/S

•  Surround waste particles (Micro-) or waste blocks with polymer (Macroencapsulation ) ▫  Mixed at high temperature, then cool or cure to form solids

•  Polymers often used ▫  Asphalt (cheap), polyethylene, polypropylene, wax, etc.

•  Advantages ▫  Wide applicability ▫  High durability, impermeability

•  Disadvantages ▫  $$$$$$ ▫  Environmental concerns

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USEPA, 1997; Conner and Hoffner, 1998; Spence and Shi, 2004; Weitzman et al., 1997

Field Setup: In-Situ •  Larger sites, waste remains on-site •  Existing lagoon as mixing basin •  Mechanical or pneumatic addition of reagent •  Mixing using backhoe or excavator •  Setting/gelling •  Off-gassing for vapors (gas cap)

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USEPA, 1986

Field Setup: Ex-Situ •  Better quality control,

smaller sites, more vapors

•  Mobile mixing •  Excavate/pump waste, mix

in mobile plants, dispose

•  In-drum mixing •  Mix, settle, and dispose in

drums

•  Area mixing •  Alternating layers of waste

and reagent, mix, compaction

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(Source: Conner, 2004)

USEPA, 1986; USEPA, 2012

Technology Selection •  Depends on:

•  Waste characteristics (most important)

•  Process type/processing requirements

•  Product management objective

•  Regulatory requirements

•  Cost

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Wiles, 1987

Compatibility of Selected Waste Categories with Different Stabilization/Solidification Techniques

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Waste Component  Treatment Type  

Cement-Based   Pozzolan-Based   Thermoplastic Microencapsulation  

Surface Encapsulation  

ORGANICS      

Organic solvents and oils  

May impede setting, may escape as vapor  

May impede setting, may escape as vapor  

Organics may vaporize on heating  

Must first be absorbed on solid matrix  

Solid organics (e.g., plastics, resins, tars)  

Good-often increases durability  

Good-often increases durability  

Possible use as binding agent in this system  

Compatible-many encapsulation materials

are plastic  

INORGANICS  

Acid wastes   Cement will neutralize acids  

Compatible, will neutralize acids  

Can be neutralized before incorporation  

Can be neutralized before incorporation  

Sulfates  May retard setting and cause spalling unless

special cement is used  Compatible  

May dehydrate and rehydrate causing

splitting  Compatible  

Halides  Easily leached from cement, may retard

setting  

May retard set, most are easily leached  

May dehydrate and rehydrate   Compatible  

Heavy metals   Compatible   Compatible   Compatible   Compatible  

Radioactive materials   Compatible   Compatible   Compatible   Compatible  

(Reproduced from: USEPA, 1986)

Treatment Costs

•  In-drum mixing most expensive and time consuming •  Lime/ash method < Portland cement method < polymer encapsulation •  Factors affecting cost: Type of waste/Size of remediation site

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Parameter   In Drum   In Situ  

Plant Mixing  

Area Mixing  Pumpable   Unpumpable  Metering and

mixing efficiency  

Good   Fair   Excellent   Excellent   Good  

Processing days required   374   4   10   14   10  

Total cost/ton ($)   224.29   32.28   38.60   48.40   41.75  

(Reproduced from: USEPA, 1986)

USEPA, 1986; USEPA, 1996; www.frtr.gov

Quality Assurance/Control •  Pre-treatment testing

•  Waste characterizing, bench and pilot scale studies

•  Post-treatment testing of freshly mixed waste •  Content of additives and contaminants, volume increase

•  Post-treatment testing of hardened waste •  Strength, leachability, permeability, durability

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Shi, 2004

Case Study #1: In-Situ treatment at South 8th Street Landfill Superfund Site, West Memphis, AR

•  A 30-acre industrial and municipal waste landfill. Between 1960 and 1970, waste oil sludge from a nearby refinery was deposited on 2.6 acres of the landfill. EPA found the oil sludge soil was contaminated with PAHs, PCBs, and lead.

•  In-situ mixing with auger reagents was utilized to remediate the soil. The following

mixing proportions were used: Soil 64.5 percent AG limestone 16.1 percent Portland cement 12.9 percent Fly ash 6.5 percent

•  Site remediation was completed over the course of two years between 1998 and 2000. Treatment costs were approximately $106/cyd. Sampling during a five year review of the contaminated site concluded that the site achieved remediation goals and chemical and physical performance standards.

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Case Study #2: Solidification of liquid waste contaminated with antimony, New Orleans, Louisiana, 1976

•  The waste was generated from a chemical plant in West Virginia and transported to New Orleans. It was tanked temporarily and prepared to be ocean-dumped, but ocean-dumping was stopped when 4,000,000 gallons of waste is still to be dumped. The waste contained high levels of dissolved organics, salts and dissolved antimony. It was a low-viscosity, semi-clear solution with very little suspended solids.

Conner, 1990; Conner, 2004

Contaminant   Concentration (wt%)  

Ethylene glycol   6.6  Diethylene   0.2  

Sodium terephthalate   2.5  Sodium chloride   8.3  Sodium sulfate   0.9  

Ammonium chloride   1.1  Antimony   0.0234  

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Case Study #2: Solidification of liquid waste contaminated with antimony, New Orleans, Louisiana(2)

•  The S/S process was treated with a combination of Portland cement and sodium silicate solution to quickly set and then harden the liquid waste.

•  A pretreatment process with hydrated lime was used to precipitate or remove some of the dissolved organics. The pretreatment help in avoiding the organic interference to cement setting and reducing the usage of S/S reagents.

Conner, 1990; Conner, 2004

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Case Study #2: Solidification of liquid waste contaminated with antimony, New Orleans, Louisiana(3)

Contaminant Concentration in Raw Waste (mg/kg)

Concentration in Treated Waste (mg/

L) Ethylene glycol 66,000 NM

Diethylene glycol 2,000 NM Sodium terephthalate 25,000 NM

Sodium chloride 8,300 NM Sodium sulfate 9,000 NM

Ammonium chloride 11,000 NM Antimony 234 0.1 Chloride NRa 160.0 Sulfate NR 5.0

Chemical oxygen demand

NMb 350.0

a NR: Not measured and reported separately as the anion, but present in compounds listed above. b NM: Not measured.

Conner, 1990; Conner, 2004

•  Wastes unregulated at the time, but they are likely to meet the limits (< 1.15mg/L). Also, the chloride, sulfate leachate concentrations and chemical oxygen demand (COD) are very small.

•  The compressive strength of the solid S/S product is as high as 4 to 5 tons/ft2 (~75 psi), allowing the products to be used as daily cover material in a local landfill (better end use)

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Case Study #3: Radioactive Waste Stabilization at the US Department of Energy Savannah River Site (SRS), SC

Overview of SRS (http://www.lasg.org)

Location of SRS (http://sti.srs.gov)

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Case Study #3: Radioactive Waste Stabilization at the US Department of Energy Savannah River Site (SRS), SC (2)

•  The Saltstone facilities, open in 1990, are part of SRS using S/S technologies to treat low-level radioactive liquid salt wastes.

•  It consists of two components: the Saltstone Production Facility (SPF) and the Saltstone Disposal Facility (SDF).

•  It processes about 30,000 gallons of waste per day. •  The objective is to stabilize liquid mixed waste to make the waste suitable for disposal in a Subtitle

D landfill.

Saltstone Production Facility (SPF) (www.flickr.com)

Saltstone Disposal Facility (SDF) (www.flickr.com)

“Fact Sheet of Saltstone Facilities”, 2012; Conner, 2004

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Case Study #3: Radioactive Waste Stabilization at the US Department of Energy Savannah River Site (SRS), SC (3)

Conner, 2004

•  Wastes •  Aqueous solution containing about 30 wt% dissolved sodium salts with

radioisotopes. •  S/S process

•  Combining S/S binders, cement, slag and fly ash, with waste solution •  Waste product is pumped over 2000 ft through a 3-inch carbon steel line and is

disposed in SDF. •  Statistics

•  3,600,000 gallons of radioactive wastes have been processed since 1990 •  100 gallons of waste solution being treated per minute •  35 tons of cementitious reagents per hour

Component   Wt% of the product  Waste salt solution with 29 wt% radioactive

dissolved sodium salts  46  

Premixed reagents  Portland cement   6  

Gound granulated blast furnace slag   24  Fly ash   24  

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References

•  A citizen's Guide to Solidification and Stabilization. (2012) EPA 542-f-12-019, USEPA •  Burdick S. A. and White R. M. (2000). “Pulse Wave Well Development Demonstration” <http://sti.srs.gov> •  Conner, J. R., Hoeffner, S. (2004). “Case Studies: Full-Scale Operations and Delivery Systems.” Stabilization and

Solidification of Hazardous, Radioactive, and Mixed Wastes, Spence, R. D. Spence and C. Shi, eds., CRC Press, Boca Raton, FL.

•  Conner, J. R. (1990) “Chemical Fixation and Solidification of hazardous wastes.” Van Nostrand Reinhold, New York. •  Engineering Bulletin: Stabilization/Solidification of Organics and Inorganics,(1993). EPA/540/S-92/015, Office of

Research and Development, USEPA, Cincinnati, OH •  Handbook for Stabilization/Solidification of Hazardous Wastes. (1986). EPA/540/2-86/1001, Office of Research and

Development, USEPA, Cincinnati, OH •  Innovative Site Remediation Technology, Design and Application, Stabilization/Solidification. (1997). Vol. 4, EPA/

542/B-97/007, Office of Solid Waste and Emergency Response, USEPA, Washington, DC •  Innovative Treatment Technologies: Annual Status Report, 10th Edition, (2001). EPA-542-R-01-004, February 2001. •  "In Situ S/S Using Soil Mixing." Geo-Solutions. <www.geo-solutions.com> •  Means, J. L. et al. (1995). “The application of Solidification/Stabilization to Waste Materials”. Lewis Publishers, Boca

Raton, FL •  “Saltstone Facilities, Fact Sheet”. (2012). Savannah River Remediation. •  Savannah River Site's photostream <www.flickr.com> •  USEPA. (1996) “Innovative Treatment Technologies, Annual Status Report”.8th Edition, EPA/542/R-96/010, USEPA,

Washington, DC. •  Sharma, H. D., and Lewis, S. P. (1994). “Waste Containment Systems, Waste Stabilization, and Landfills: Design and

Evsuialuation.”Wiley, New York •  "Soil Stabilization Brings New Life to Old Utility Site" Slag Cement Association. <www.slagcement.org> •  "Soil mixing & Soil Stabilization." WRS Compass. <www.wrscompass.com> •  Spence, R. D. and Shi, C. J. (2005). “Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes.”

CRC Press, Boca Raton, FL •  Stabilization/Solidification of CERCLA and RCRA Wastes: Physical Tests, Chemical Testing Procedures, Technlology

Screening, and Field Activities. (1989). EPA/625/6-89/022, Office of Research and Development, USEPA, Washington, DC

•  United Retek of Connecticut, LLC. <unitedretekofct.com>

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More  Informa7on  More  detailed  technical  informa7on  on  this  project  can  be  found  at:  hEp://www.geoengineer.org/educa7on/web-­‐based-­‐class-­‐projects/

geoenvironmental-­‐remedia7on-­‐technologies