Cost performance curves A tool to evaluate

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

Background Drs Ben Keet Free University of Amsterdam : Physics & Hydrogeology Work experience • • • Ø Ø 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 www. benkeet. com 2

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 www. benkeet. com 3

Uncertainties keep in mind: What we know is not much What we know we don’t know is limited But what don’t we know we don’t know ? www. benkeet. com 4

Groups of Uncertainties 1. 2. 3. 4. 5. Initial conditions Effect of chosen remedial technique(s) Quality of implementation Technical uncertainties Contractual uncertainties www. benkeet. com 5

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

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 www. benkeet. com 7

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

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Technical uncertainties Just a few: • Presence of sulphides – acid soils • Change of redox – mobilisation (As) • NA of VOCl’s formation of VC (gas) www. benkeet. com 10

Contractual uncertainties § § Definition of goals vs. definitions of the deliverables Final sampling methodology Allowable residual risk / contaminants Ownership intellectual property www. benkeet. com 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 www. benkeet. com 12

4 scenarios: 0 = no added activity I, III = addition of several in situ techniques www. benkeet. com 13

Set out cost vs. kg contaminant removed Conclusion: Simplest system will eventually remove same oil mass at lowest costs www. benkeet. com 14

Now evaluate S/kg in time www. benkeet. com 15

Conclusions this Case With the added knowledge of hint sight: In this case 1. Full excavation immediately after spill gives highest cost efficiency 2. Note added cost to shut down operations 3. Plus cost for demolition / rebuilding glass house www. benkeet. com 16

Conclusion CP curves 1. Allows technique independent comparison 2. Easy to explain to lay person However: 1. Requires thorough insight in techniques 2. Requires firm costing of alternatives 3. Requires identification of residual uncertainties www. benkeet. com 17

Questions - Discussion www. benkeet. com 18