Background chemicals are widespread Challenges: Health and Safety Contaminated Media Management Disposal Planning and B

1. Background – Who Cares? • Background chemicals are widespread Challenges: • Health and Safety • Contaminated Media Management • Disposal • Planning and Budgeting • Paul Seidel – Toxicologist, Oregon Department of Environmental Quality • Chris Breemer, R.G. – Principal Geologist, Ash Creek Associates TRB Conference 2011, Portland, Oregon

2. Objectives • Background identification methods • Managing background-impacted media • Introduce Oregon’s forthcoming background metals project • Applications • Process TRB Conference 2011, Portland, Oregon

3. What and Where Are They? • Anthropogenic: • Polychlorinated biphenyls (PCBs) • Polycyclic aromatic hydrocarbons (PAHs) • Dioxins/Furans • Pesticides/Herbicides • Metals • Naturally Occurring: • Metals Agricultural soil ● Mining districts ● Urban soil ● Sediment TRB Conference 2011, Portland, Oregon

4. Is it Background or Not? – Pt. 1 Collect Data → Evaluate Data • Collect Data From Multiple locations • Can be expensive • Requires careful planning • Complicated by natural variability • Costs can be limited by compositing or incremental sampling methodology(expensive for deep samples) TRB Conference 2011, Portland, Oregon

5. Is it Background or Not? - Pt. 2 Collect Data → Evaluate Data • Evaluate Data • Look up tables • Statistical evaluation Oregon Default Background Concentrations TRB Conference 2011, Portland, Oregon

6. Managing Impacted Media • Benefits of Naturally-Occurring Determination • Simplified regulatory status • Simplified NEPA/SEPA process • Eased property acquisition/divestiture • Management of Impacted Media • Health and Safety • Re-use on-site TRB Conference 2011, Portland, Oregon

7. Managing Impacted Media • Anthropogenic • Minimize disturbance (geotechnical solutions) • Cap in-place (regulatory involvement; federal/state limitations) • Off-/On-site disposal (SWLA) • Disposal under “Beneficial Use” rules (OAR 340-0260) • Landfill TRB Conference 2011, Portland, Oregon

8. Background Metals Project

9. Background Metals Project Basis and Rationale • ODEQ (2002) published estimates of background for select metals. However, • Some data sets are not specific to Oregon; • Only point estimates published, underlying data sets not available • Do not account for geographical or geologic variability • ODEQ (2010) began a project to compile Oregon-specific database of metals representative of ambient soil conditions.

10. Background Metals Project Database Development Issues and Contents • Multiple data sources compiled representing various Federal, State and University projects collected over > 10 years • Converted all to common units (mg/kg) • Convert to common horizontal datum • Assign samples to one of 8 physiographic provinces • 6,118 Samples, 54 unique elements • > 20,000 analytical results or imputed values

11. Background Metals Project Extensive Pre-Processing/Data Cleaning • Treatment of Non Detected Values • Created a weighted average • Identification and Screening of Outliers • Based on percentiles • Multiple samples at the same coordinates • Averaged over surface interval • Identification of data gaps and de-clustering • Address spatial bias across State

12. Background Metals Project Database Development Issues

13. Background Metals Project Arsenic – Current Default – 7 mg/kg ARSENIC

14. Background Metals Project Arsenic – Current Default – 7 mg/kg ARSENIC

15. Background Metals Project Methods for Determining Site-Specific Background • Lookup Tables & Summary Statistics • Simple but potential for wrong decision • Which Statistic- Mean, UCL, UPL, UTL, Max? • Hypothesis Testing: • More informative and complex • Still some potential for wrong decision

16. Background Metals Project Formal Hypothesis Tests • Parametric (normality, equal variance) • Nonparametric (Rank-Sum, bootstrapping) • More informative and complex • Can be used inappropriately • Sufficient sample size and form of test can be important factors.

17. Background Metals Project Boxplots of Site vs. Willamette Valley Reference

18. Background Metals Project Example Robust Test – Bootstrapping Approach

19. Background Metals Project Summary • New database available for Oregon background metals. • Our approach to estimating background is under development- likely will allow flexibility, more than 1 method. • Methods and approach are more generally applicable on a variety of projects and other States.