1. Co-Located Chemical Sampling Planned Sampling Approach Laura Rainey Department of Toxic Substances Control October 12, 2010

2. Goals for Co-located Chemical Sampling Effort  Opportunity to obtain additional chemical data (co-located with radionuclide data) to assist in identifying key chemical contaminants that may drive cleanup decisions.  Takes advantage of all the additional information that EPA has obtained to target sampling (EPA Historical Site Assessments, Gamma Scanning Data, Geo-physical logging, former worker interviews, aerial photography analysis).

3. Key Differences  The Agreement in Principle envisions “split” sampling Decision made to co-locate chemical sampling due to chemical sampling needs:  Amount of soil volume needed due to differences in radionuclide and chemical analytical method needs  Chemical sample interval based on RFI/RI approach and utilizes field screening and visual observations

4. Key Differences: Rad vs. Chemical Sampling  Amount of soil volume needed  Volume required dependent on EPA chemical analytical method requirements  Sample collection and handling Homogenization over depth interval (rad) vs. discrete sampling (chemical) Chemical analyses utilize EPA analytical methods  Chemical sample depth interval Selection based on RFI/RI approach Discrete depths selected based on site features (including excavations/fill areas), screening and visual field observations

6. Sampling Intervals  Placeholder for 5B chart

7. Table of Analytes-- Primary Analyses (anticipated to be performed on all collected soil samples): AnalysisEPA Method (unless otherwise listed) Volatile Organic Compounds8260B Metals6010/6020B Mercury7471A Chromium VI7196A or 7199 Semivolatile Organic Compounds8270C Polycyclic Aromatic Hydrocarbons8270 SIM Perchlorate314.0 Polychlorinated Biphenyls8082 Fluoride300.0/9056A Dioxin/Furans1613B Total Petroleum Hydrocarbons (gas/oil/diesel)8015B Percent Moisture160.3

8. Table of Analytes-- Secondary Analyses (performed on selected soil samples): AnalysisEPA Method (unless otherwise listed) 1,4-Dioxane8260B SIM Formaldehyde8315A Hydrazine8315A n-Nitrosodimethylamine1625C Energetics8330A Cyanide9012B pH9045C Alcohols8015B Terphenyls8015B Glycols8015B Methyl Mercury1630 Organic TinNOAA Status and Trends Asbestos600/R-93/116 Pesticides8081A Herbicides8151

9. DTSC Oversight  DTSC will: Periodically observe sampling in field to ensure procedures are being followed Participate in quality audits of the laboratories Obtain quality control split samples to be sent to DTSC laboratory

10. Conclusions  Chemical co-located sampling will be a significant input to DTSC for purposes of determining the nature and extent of residual chemical contamination in Area IV and the Northern Undeveloped Land