USE OF PORE WATER IN CONJUNCTION WITH OTHER BIOTIC AND ABIOTIC DATASETS TO EVALUATE REMEDIAL SUCCESS IN A FRESHWATER RIVER ENVIRONMENT Hudson – Delaware SETAC Fall 2015 Meeting October 7, 2015

2 Utility of Pore Water Data in a Changing Environment Project Background –Operational History –Conceptual Site Model Pilot Bank Stabilization Project –Design –Baseline and Post-Implementation Monitoring Data Summary Lessons Learned and Implications for Future Monitoring Overview

2016: Construction begins 2014: South River enters into regulatory process The South River Story : Mercuric sulfate use stops 1982: Studies predict fish improvement in 20 years 1999: Fish tissue levels are not decreasing as predicted 2001: DuPont and VDEQ launch collaborative effort – South River Science Team 1929: Mercuric sulfate use in acetate rayon fiber production begins 1976: Mercury discovered on- site and in fish; fish consumption ban 1984: DuPont funds 100- year monitoring program : Baseline monitoring begins : Extensive field investigations

Site Location N Waynesboro, VA Fibers Plant DuPont INVISTA present

Conceptual Site Model 5

6 Pilot Bank Stabilization Project Elevated THg Concentrations in Biotic and Abiotic Media Erosion Documented Using Side- Scan LiDAR Approximately 500’ Stabilized

7 Pilot Bank Stabilization Project Pre-Stabilization Conditions

8 Pilot Bank Stabilization Project

9 Performance Monitoring Program Physical Elements Channel Morphology EPA Rapid Bioassessment Protocol Chemical Elements Surface Water Bank Soil Sediment Pore Water Asiatic Clam

Baseline Data Review 10

11 Baseline Mercury Characterization: Highest THg Concentrations in Sediment Co-located with Soil

12 Pore Water Hg Concentrations are Highest Near Pilot Bank

Post Stabilization Data Review 13

Sediment Decreased THg Concentrations on Average Compared to Pre-stabilization Data Maximum THg Concentrations Have Decreased Since 2012 Sediment THg Concentrations Similar to Those Observed on Particles in the Water Column Bank Stabilization

Pore Water Extensive Variability in Baseline Dataset Prevents Detecting Statistically Significant Reductions Continued Decreasing Trend in IHg and MeHg Concentrations Over Time Bank Stabilization

Pore Water

Asiatic Clam Tissue IHg Concentrations Similar Between Near-bank and Mid-channel Samples Typically Higher MeHg Concentrations in Near-bank Samples Bank Stabilization

Asiatic Clam - Comparison to Baseline Corbicula IHg Corbicula MeHg

Sediment and Pore Water – Comparison to Baseline

20 Lessons Learned - Monitoring Implications Bank Stabilization Pore Water Data Most Strongest Line of Evidence Documenting Remedy Success Other Lines Of Evidence Provide Useful Information in a Changing Environment Phase 1 Interim Measures Expected to Begin in 2016

South River Science Team (SRST) DuPont City City of Waynesboro College of William and Mary James Madison University Virginia Tech University of Delaware University of Waterloo Colorado State University Western Washington University Texas Tech University Will Clements Dave Hirschman Ralph Turner Expert Panelists Academia Friends of the Shenandoah Virginia Conservation Council Trout Unlimited Shenandoah River Keeper NGOs Federal State EPA USF&WS VDEQ VDGIF VDH Consultants AECOM Anchor QEA Engineers Geologists Risk assessors