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Cost – performance curves

Cost – performance curves. A tool to evaluate alternative remedial options before and during projects. Background Drs Ben Keet. Free University of Amsterdam : Physics & Hydrogeology Work experience 5 years Ass. Lect. Physics & Groundwater Models

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Cost – performance curves

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  1. Cost – performance curves A tool to evaluate alternative remedial options before and during projects

  2. Background Drs Ben Keet • Free University of Amsterdam : Physics & Hydrogeology • Work experience • 5 years Ass. Lect. Physics & Groundwater Models • 5 years Shell International : UK, Algeria, Gabon, London • 19 years Geo & Hydro: New Zealand, Australia, US, Europe, NZ • Proj. manager 2500 site assessments, 1500 remediations • Design & manage : 400 in situ & biological remediations

  3. CP curves: Conditions of use • Good understanding of uncertainties involved • Thorough knowledge of effects of remedial techniques to be evaluated • Cost estimates need to be complete • Accurate and relevant monitoring data

  4. What we know is not muchWhat we know we don’t know is limitedBut what don’t we know we don’t know ? Uncertainties keep in mind:

  5. Groups of Uncertainties • Initial conditions • Effect of chosen remedial technique(s) • Quality of implementation • Technical uncertainties • Contractual uncertainties

  6. Initial conditions • Heterogeneity : • Soil • Contaminants • Time • Contaminant movement • Retardation (actual) • Leaching (TCLP) • (Re-) mobilisation

  7. Effect of chosen remedial technique(s) • - Breakdown speed (half-life time) • - The natural or enhanced breakdown potential • - Leaching / migration potential (current, during and after remedial action) • - Lowest possible attainable concentration by mixing or bioremediation

  8. Quality of implementation • Focus on results • Use soil heterogeneity • Monitoring aimed at • System check • Process control • Effect monitoring • So not only Verification

  9. Technical uncertainties Just a few: • Presence of sulphides – acid soils • Change of redox – mobilisation (As) • NA of VOCl’s formation of VC (gas)

  10. Contractual uncertainties • Definition of goals vs. definitions of the deliverables • Final sampling methodology • Allowable residual risk / contaminants • Ownership intellectual property

  11. Cost – performance curves Case - midpoint evaluation • oil spill ½ under glass house • Emergency response : • Dig trench • Pump fluid to oil/water separator • After 21 months evaluate alternatives

  12. 4 scenarios:0 = no added activityI, II, III = addition of several in situ techniques

  13. Set out cost vs. kg contaminant removed Conclusion: Simplest system will eventually remove same oil mass at lowest costs

  14. Now evaluate S/kg in time

  15. Conclusions this Case With the added knowledge of hint sight: In this case • Full excavation immediately after spill gives highest cost efficiency • Note added cost to shut down operations • Plus cost for demolition / rebuilding glass house

  16. Conclusion CP curves • Allows technique independent comparison • Easy to explain to lay person However: • Requires thorough insight in techniques • Requires firm costing of alternatives • Requires identification of residual uncertainties

  17. Questions - Discussion

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