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Section 4- Characterization

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

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Section 4- Characterization

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  1. 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

  2. Conceptual Site Model Development First and most important step in remediation project includes • 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

  3. Contaminant Mass PSH, Sorbed, Dissolved •

  4. Total Mass EvaluationNature of Contamination • 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 Graphic source: Suthersan, 1996

  5. Total 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

  6. Treatment Volume Estimate •

  7. Value 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)

  8. Site Geochemistry/Geology •

  9. 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)

  10. Site Geochemistry/Geology •

  11. Conditions 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

  12. Special Site Model Considerations No Utilities I-55 Limited Access Highway Private Property Access Only Pipeline Surface Water Body Flood Prone Area with Dirt Roads

  13. 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

  14. Target Interval Conceptual Site ModelTarget Interval Identification Soil Conductivity Contaminant Mass

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