1 Section 6- ISCO DESIGN  Initial Site Evaluation  ISCO Compatibility  ISCO Modeling and Dosage Considerations  Bench Testing  Pilot Testing/Delivery System Evaluation  Full Scale  Combination Technologies

2 ISCO Design Process Initial Technology Screening Modeling Design Parameter Evaluation and Bench Testing Field Pilot/Initial Application Full Scale Application

3 Example Laboratory Test Oxidation Estimating Tool (OET) is predictive empirical model to estimate overall oxidant demand (OD) Stochiometry is only a small fraction of the actual oxidant required for ISCO Treatability test is run on several formulations to develop an efficiency curve and confirm OD The primary purposes of the OET are: 1. To determine the reactivity of the site media 2. To select the optimum reagent formulation 3. To observe adverse reactions, if any

4 OET Model Site Geochemistry/Geology Well Contaminants-Total Mass Treatment Volume Estimate

5 Site Geochemistry/Geology UnitsValue Range LimitsNotes Porosity%0.3 Permeabilitymd ,000 pHs.u.6.5<8.5 Specific conductanceuS/cm Groundwater temperature 0F0F Groundwater velocityft/day

6 Site Geochemistry/Geology UnitsValue Range LimitsNotes Redox potential (ORP)mV070 - (-70) Grain sizemm % pt. Dissolved oxygen (DO)ppm TDSppm TOC in groundwaterppm4<40 Hydroxyl scavengerppm100<400 Well diameterinch11/2 new SS

7 Contaminant Mass PSH, Sorbed, Dissolved CleanOX Appl. Well Existing MW Number of Wells Total VOCs (average for all Areas)ppm850 Area x7510 TICppm0 Area x130 (includes Area 1)35 TPH/Cosolvents ppm 0Area x Multiply the number of wells times the reagent requirement Total Contaminant Loadppm850

8 Treatment Volume Estimate CleanOX Appl. Well Existing MW Radius of Influenceft20 Area of Influencesft1258 Screen Depth, topft5 Screen Depth, bot.ft30 Total Treatment Volumecft31450 Total Groundwater Volumegal70583 Total Groundwater Weightlb588744

9 Design of Delivery Systems  Sufficient number of wells to provide adequate overlap of “effective zones” Can use trenches  Usually multiple application events  Oxidant transport can be reaction limited Effective radius of treatment will be substantially smaller than hydraulic/pneumatic radius of influence Higher oxidation reaction rates lead to smaller treatment radii  Caution should be used when designing injection / monitoring wells Stainless steel injection points may be needed

10 Pilot Test Design Bench test predicts best oxidant and combination of reagents only Pilot Calibrates Bench Prediction Identifies application parameters for full site design Develops optimal delivery process

11 Conditions that Require Special Delivery Consideration  Low permeable soils  Deep aquifers  LNAPL/DNAPL  Confined formations  Swamps or high organic soils  Old landfills and dumps  River embankments  Under buildings

12 Important Delivery System Considerations  Only treat sites that have been properly characterized  Treat from the perimeter of the target zone  Never treat within or down-gradient of contamination  Perform treatment to address all phases of Contaminant  If rebound occurs, realized that it is an indication of contamination not be contacted (within, above, next to, or below) not that ISCO does not work.

13  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 (K ow ) determines the relationship between phases in the saturated zone  Majority of mass (normally >80%) is sorbed and phase-separated Total Mass Evaluation Nature of Contamination Graphic source: Suthersan, 1996

14 Delivery Systems Batch vs. Recirculation Batch Oxidant Injection Oxidant Recirculation Injection wells Extraction wells Contaminant Injection location Radius of treatment

15 Delivery Systems Application Conventional delivery configurations  Direct injection  Horizontal injection  Pulsing  Soil mixing  Density-driven flow  Lance permeation Treated soil columns Bedrock Soil Auger Water table

16 Delivery Systems Enhancement Innovations to increase effectiveness  Recirculation  Pneumatic fracturing  Hydraulic fracturing  Ozone sparging  Unsaturated zone delivery

17 Design Conclusions  Always perform limited Bench Evaluation  Pilot is needed to optimize delivery of Reagents  Mass transfer technologies limited in their effectiveness because they must rely on the natural slow and inefficient desorption of the contaminants of concern from the soil  ISCO enhances mass transfer from soil to groundwater by breaking down natural organic matter (NOM) (and sorption sites) and increasing temperature (peroxide co-addition)  Biological System rebounds effectively after ISCO