Risk Assessment Methodologies in Ranking Decontamination Actions on National and Local Level. a Hungarian Experience

Transcription

1 Risk Assessment Methodologies in Ranking Decontamination Actions on National and Local Level a Hungarian Experience a workshop on Contaminated Lands in Accession Countries: Benchmarking Historical Heritage and National Actions The Regional Environmental Center, November, 2003, Szentendre, Hungary Organised by the Joint Research Centre and by the DG Environment of the European Commission Dr. Ferenc Gondi BGT Hungaria Environmental Technology

2 Environmental Risk The nature and probability of occurrence of an undesirable adverse effect on human health and/or on the environment! What effects on humans, animals, plants and the environment! how likely is it! what are the consequences 2. slide

3 Quantitative vs. Qualitative Quantitative risk ranking! operates with relative categories Qualitative risk assessment! operates with particular values and numbers Hazard Definition EXPOSURE ASSESSMENT EFFECTS ASSESSMENT RISK CHARACTERIZATION 3. slide

4 National Priority List of Polluted Sites A policy tool, based on qualitative risk ranking! allows to set up priority list of polluted sites! operates with relative categories as toxic properties of materials used on site landuse and sensitivity categories presence of receptors 4. slide

5 Basics of Risk Assessment Receptors air Source soil Transport Groundwater 5. slide

6 Steps of the Quantitative Risk Assessment Csource Qualitative ranking Project Scoping Site Assessment Exposure assessment ADI, PEC Toxicity Assessment Monitoring programm Remedial action Risk Characterization ADI/TDI, PEC/PNEC TDI, PNEC 6. slide

7 1. Site Assessment " Site location, history, " Inventory of potential hazardous materials and sources " Identify the landuse " Identify potential migration pathways, " Investigate and assess environmental impacts " and receptors 7. slide

8 1.1. Impact on Soil and Groundwater Groundwater migration 8. slide

9 1.2. Contaminant Characterisation! diffusion in air! molecular weight! diffusion in water! distribution coefficient K d = K OC x f OC! toxicity! ecotoxicity! solubility! Henry constant, vapor pressure! biological availability! adsorption factor! biodegradability 9. slide

10 2. Exposure Assessment 2.1. Migration pathways volatilization to ambient air volatilization to indoor air volatilization drinking water transport and uptake by plants and animal contaminant leachnig to grondwater transport to surface water 10. slide

11 2.2. Modelling contaminant transport in groundwater with site specific values! geological-hydrogeological parameters - depth to groundwater - capillary zone thickness - vertical hydraulic gradient - fraction of organic carbon in water-bearing unit rain - groundwater flow direction volatilization - surface waters - groundwater mixing zone depth - average infiltration -... surface water Saturated zone Soil Pore water condensation volatilization river evaporation aquitard leaching groundwater movement Vadose zone Pore air water film spring 11. slide

12 2.3. Modelling contaminant transport in air with site specific values! Ambient air characteristic - distance to offsite inhalation receptor - wind speed - air stability -.. etc.! Buildings characteristic - Foundation crack thickness - Foundation crack fraction - Building air exchange rate, ratio -.. etc. air condition foundation vapor groundwater 12. slide

13 2.4. Exposure pathways Ingestion Direct contact Inhalation 13. slide

14 2.5. Conceptual site modell Primary Sources Secondary sources Transport mechanism Exposure pathways Receptors Product storage Operations Pipingdistribution Impacted surfical soil Impacted Subsurface soil Dissolved groundwater plume Free-Phase liquid plume Wind erosion and atmospheric dispersion Volatilization and atmospheric dispersion Volatilization and enclosed space accumulation Leaching and groundwater transport Free-phase migration Soil ingestion/ adsorption Inhalation Potable water use residental commercial Sensitive habitat residental commercial Sensitive habitat residental commercial Sensitive habitat 14. slide

15 2.6. Estimation of Exposure Average Daily Intake [mg/kgxday]: ADI = C * DAF * (IR * EF * ED)/(BW * AT) - C: max. contaminant concentration in the source [mg/kg, mg/l] - DAF:(C/C R ) dilution-attenuation factor on the migration pathway (dilution, dispersion, degradation..) - IR: ingestion rate [l/day, kg/day, m 3 /h] - EF: exposure frequency [day/year] - ED: exposure duration [year] - BW: body weight [kg] - AT: averaging time for toxic and carcinogenic substances [year] 15. slide

16 3. Toxicity assessment NOAEL NOEC PNEC LD50, LC50, RfD, TDI... Toxic Percent Response Effects Assessment (e.g., dose response) Low LC 50 Concentration or Dose High Carcinogen Slope Factor Unit Risk IRIS, HEAST! Acut-,! Chronic-,! Multi-generation studys 16. slide

17 4. Risk calculation Environmental concentration x Exposure factors x Toxicity = Risk Risk assessment e.g.: ADI/TDI=HQ Calculation of risk based target level eg.: HQ=1, ADI=TDI c=tdi/em 17. slide

18 4.1. Assessment steps! Tier 1: - default parameters - sensitive landuses - onsite receptors only! Tier 2: - site specific parameters - onsite and offsite receptors - simplified transport modells! Tier 3: - more site specific parameters - onsite and offsite receptors - more complex transport modells - specific toxicity assessment Risk assessment Tier 1. Tier 2. Tier slide

19 4.2. Articulated Hungarian Requirements Regional and hydraulically continuous aquifers, and the strategical importance of groundwater in Hungary explains articulated Hungarian requirements in the application! transposal of contamination into uncontaminated elements of the environment is not allowed! expanding of the dissolved contamination plume is not allowed 19. slide

20 4.3. Schematic Cross Section of the Carpathian Basin 20. slide

21 4.4. Site specific target level (SSTL) Rain Contaminanat source Compliance point Receptor Leaching to groundwater Groundwater plume Predicted plume Contaminated area SSTL 2 Concentration SSTL 1 Dilution Distance Sorption, degradation Tolerable conc2 Tolerable conc1 21. slide

22 4.5. Potential receptors Onsite Border Offsite Volatilization } Vadose zone Contaminated groundwater Predicted plume } Saturated zone Aquitard Leaching } Second aquifer Potential receptor Potential water use Receptor Actual water use Background concentration 22. slide

23 5. Risk Reduction 1. Source control 2. Interruption of transport routes 3. Landuse restrictions 4. Monitored Natural Attenuation 23. slide

24 Experience on Benefits and Acceptance Risk based approach may provide a useful decision support tool in policy implementation Hungarian legislation accepts the risk approach in establishing priorities and target values Fears and reluctance in daily practice, mostly caused by the lack of detailed knowledge on the limits of application Practical application requires the regular training of all the stakeholders - authorities, problemholders, NGOs 24. slide