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Introduction to Atlantic RBCA Version 3

Introduction to Atlantic RBCA Version 3. Webinar May 4, 2013. Attending Today’s Session. Hosting Tania Noble, Stantec Michel Poirier, NBENV Ulysses Klee, Stantec You – People who have taken the on-line course. Outline. Quick Navigation (Webinar)

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Introduction to Atlantic RBCA Version 3

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  1. Introduction to Atlantic RBCA Version 3 Webinar May 4, 2013

  2. Attending Today’s Session • Hosting • Tania Noble, Stantec • Michel Poirier, NBENV • Ulysses Klee, Stantec • You – People who have taken the on-line course

  3. Outline • Quick Navigation (Webinar) • Questions asked during course or submitted for the webinar • Reminder of topics/other questions on theory • Review Case Studies from course

  4. Q1 – Incorporating lab results

  5. Q1 – Incorporating lab results

  6. Q2 –Modeling different pathways

  7. Q2 –Modeling different pathways

  8. Q2 –Modeling different pathways

  9. Q2 –Modeling different pathways

  10. Q2 –Modeling different pathways • Best Practice: • Run each pathway separately • Indoor Air (x 10) • Dermal Contact and Soil Ingestion • Groundwater Ingestion • Run TEX separately from TPH Might seem like a lot of runs for some sites, but it will greatly reduce the chance of error

  11. Q3 – Minimum Requirements for AF=10? • Same as basic requirements for using model • Concrete floor • 30 cm clean soil separation • Can still adjust other building parameters as usual and apply AF=10 for BTEX/TPH

  12. Q4 – How can you adjust crack fraction? • Crack fraction = Acracks/Abldg • Default crack fraction assumes: • Perimeter crack only • From CWS: crack width = 0.2 cm for residential, = 0.26 cm for commercial • For all other openings, note dimensions, calculate area, and add to perimeter crack

  13. Q5 – Adjust for dirt floor (internal purposes only) • Technically: Adjust the crack fraction to 1.0 • Note: Once you go beyond the range of “typical” values (0.0001 to 0.01), model may become unstable, and results may become very sensitive to other parameters

  14. Q6 – Relevant Parameters for Indoor Air Pathway • Does depth to contamination matter? • Depends. If diffusion through soil to foundation is dominant process, yes • If advection dominates, then SSTL is not sensitive to depth to contamination

  15. Q6 – Relevant Parameters for Indoor Air Pathway • Does area of contamination matter? • Area of impact on soil input parameters does not affect SSTL for indoor air pathway • Account for soil area through volume to area ratio

  16. Q7 – Equation for estimating dispersivity • Xu and Eckstien equation is recommended over ASTM

  17. Q8 – What if you don’t know the wind direction? • For air dispersion model, if you don’t know wind direction, assume receptor is directly downwind • Similar recommendation for groundwater dispersion if you are uncertain about groundwater direction

  18. Reminder of the Topics • M1 – Introduction • M2 – Overview • M3 – RA Fundamentals • M4 – Evaluating Exposure Pathways • M5 – Fate and Transport • M6 – ARBCA Model Issues • M7 – Model Sensitivity • M8 – Navigating the ARBCA Toolkit • M9 – Version 2 User Guidance • M10 – Soil Vapour & IA Monitors • M11 – Atlantic Regulatory Process • M12 – Final Test

  19. Case Study #1

  20. Case Study #1 • Provided only 1 soil sample and 2 MW samples & table of site-specific conditions • Assumptions: • Full site characterization has been completed • Building has no major openings in concrete floor and is at least 2 levels

  21. Case Study #1

  22. Case Study #2

  23. Case Study #2 • Provided limited sample results; no info on surrounding land use • Assumptions: • Full site characterization has been completed • Building has no major openings in concrete floor • Surrounding land use is commercial • Mixed use on-site – residential most conservative

  24. Case Study #2 – Gas/Diesel

  25. Case Study #2 – Weathered Diesel

  26. Case Study #3

  27. Case Study #3 • Original report and assessment dates back prior to 2003 • Did you pick up on changes between how report was RBCA was used then, versus how you did it now? • How did you address: • Vapour screening? • Bedrock • Off-site wells?

  28. Case Study #3 • What assumptions did you have to make? • What other information would you have liked to have? • Based on your assessment, does this site require further mediation or risk management?

  29. Suggestions or comments

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