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Section 4- Characterization

Characterization is 95% of the Success of ISCO Develop a complete and comprehensive

Conceptual Site Model ISCO is a Mass Destruction Technology Successful Treatment must Identify both target

and non target analytes and contain all phases of Mass

Know Flow paths within soil Structure

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Conceptual Site Model Development

Characterization of nature and mass of contaminants present• Sorbed• Dissolved• Free product phases

Subsurface geology, site topography, aquifer geochemistry

Identification of major migration pathways for contaminants of concern (COC)• Surface and subsurface structures• Underground utilities

Direction / gradient / velocity of groundwater flow Surface water features / uses, and potential receptors in

the area

First and most important step in remediation project includes

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Contaminant MassPSH, Sorbed, Dissolved

Appl. Well  

Existing MW  Number of Wells

Total VOCs (average for all Areas) ppm 850

Area 1 - 100x75 10

TIC ppm 0Area 2 - 300x130 (includes Area 1) 35

 TPH/Cosolvents  ppm  0 Area 3 - 185x 125 20

     Multiply the number of wells times the reagent requirement

Total Contaminant Load ppm 850

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Contamination mass exists in four phases in the contaminated zone• Soil gas

• Sorbed

• Dissolved

• Non-aqueous phase liquid (NAPL) or phase-separated

Geochemistry, partitioning coefficient (Kow) determines the relationship between phases in the saturated zone

Majority of mass (normally >80%) is sorbed and phase-separated

Total Mass EvaluationNature of Contamination

Graphic source: Suthersan, 1996

5Total Mass EvaluationImportance of Mass Calculations

Evaluate pre- and post- total contaminant mass

Sorbed and non-aqueous phase mass converts to dissolved during treatment and until site reaches post treatment final equilibrium

Possible “rebound” causes• Dissolution of sorbed or non-aqueous phase

• Inadequate site characterization

• Change in groundwater flow direction

Decrease in total mass may not be reflected in short-term dissolved concentrations Electroconductivity

Diagram

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Treatment Volume Estimate

CleanOX Appl. Well  

Existing MW  

Radius of Influence ft 20

Area of Influence sft 1258

Screen Depth, top ft 5

Screen Depth, bot. ft 30

Total Treatment Volume cft 31450

Total Groundwater Volume gal 70583

Total Groundwater Weight lb 588744

7Value of Data Quantity vs. Certified Analytical Data

ISCO requires contaminant delineation, precise concentration data quality not as critical as for closure confirmation

References – available at www.itrcweb.org under “Guidance Documents”• ITRC Technical and Regulatory Guidance for the Triad

Approach: A New Paradigm for Environmental Project Management (SCM-1, December 2003)

• ITRC Strategies for Monitoring the Performance of DNAPL Source Zone Remedies (DNAPLs-5, August 2004)

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Site Geochemistry/Geology

Site Geochemistry/Geology Units ValueRange Limits Notes

Porosity % 0.3    

Permeability md 3574.237 1 - 10,000  

pH s.u. 6.5 <8.5  

Specific conductance uS/cm 500 100 - 6000  

Groundwater temperature 0F 65 32 - 130  

Groundwater velocity ft/day 0.020.0001 -

0.2  

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Oxidant Demand Nomenclature

Natural oxidant demand (NOD) Soil oxidant demand (SOD) Total oxidant demand (TOD) Natural organic matter (NOM) Standard laboratory measurements of oxidizable

matter in groundwater include• Chemical oxygen demand (COD)

• Total organic carbon (TOC)

• Total inorganic carbon (TIC)

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Site Geochemistry/Geology

Site Geochemistry/Geology Units Value Range Limits Notes

Redox potential (ORP) mV 0 70 - (-70)  

Grain size mm 0.07  10% pt.

Dissolved oxygen (DO) ppm 4 0.01 - 25  

TDS ppm 500 50 - 1500  

TOC in groundwater ppm 4 <40  

Hydroxyl scavenger ppm 100 <400  

Well diameter inch 11/2  new SS

11Conditions that Require Special Consideration

Low permeable soils Deep aquifers LNAPL/DNAPL Confined formations Swamps or high organic soils Old landfills and dumps River embankments Under buildings

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Surface Water Body

Pipeline

I-55 Limited Access Highway

Private PropertyAccess Only

No Utilities

Flood Prone Area with Dirt Roads

Special Site Model Considerations

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Lithology and Flow Path

Borings need to be properly installed by experienced personnel, which is contrary to reimbursement program pricing

Fine Sand lenses and variations in permeability are difficult to determine with Geoprobe programs

Wells need to be properly screened and developed (not three well volumes as in PST programs)

Confining layers are critical

14Conceptual Site ModelTarget Interval Identification

Target Interval

Contaminant MassSoil

Conductivity