1. Monitored Natural Attenuation of Metals and Radionuclide-Contaminated Sites Pat Brady Sandia National Laboratories Mike Truex Pacific Northwest National Laboratory Chuck Newell GSI Karen Vangelas Savannah River National Laboratory Miles Denham Savannah River National Laboratory Sponsored by: DOE EM-22 Attenuation-Based Remedies for Metals and Radionuclide Project (Leads: M. Denham and K. Vangelas, Savannah River National Laboratory) Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

2. 2 http://www.epa.gov/ada/download/reports/ 600R07139/600R07139-01.pdf http://www.epa.gov/ada/download/reports/ 600R07140/600R07140.pdf Volume 3 Assessment for Radionuclides Including Isotopes of Cesium, Iodine, Neptunium, Plutonium, Strontium, Technetium, and Uranium In Preparation Recent EPA Guidance for MNA of Metals and Radionuclides

3. 3

4. 4 The Scenarios Approach

5. 5

6. 6

7. 7 Example: Uranium Example: Arsenic

8. 8 Enhanced Attenuation