SITE INVESTIGATION REPORT FOR THE CATTLEHEAD CDV SITE United States Forest Service, Southern Region Ozark St. Francis National Forest Contract No. AG-43ZP-D-15-0007 Prepared for: U.S. Department of Agriculture United States Forest Service, Southern Region Atlanta, Georgia 30309 Prepared by: BMT Designers & Planners, Inc. 4401 Ford Avenue, Suite 1000 Alexandria, Virginia 22302 March 2019 TABLE OF CONTENTS 1. INTRODUCTION ................................................................................................................................... 1 2. GENERAL BACKGROUND ................................................................................................................... 3 3. SITE LOCATION AND PHYSICAL SETTING ....................................................................................... 4 3.1. Site Location .................................................................................................................................. 4 3.2. Topography ................................................................................................................................... 4 3.3. Geology ......................................................................................................................................... 4 3.4. Hydrogeology ................................................................................................................................ 5 3.5. Surface Water ............................................................................................................................... 6 4. DESKTOP DATA COLLECTION AND SITE RECONNAISSANCE ...................................................... 7 4.1. Site Description ............................................................................................................................. 7 4.2. Surrounding Property Description ................................................................................................. 7 4.2.1. Sensitive Receptor Survey .................................................................................................... 8 4.3. Historical Aerial Photograph Review ............................................................................................. 9 4.4. Operational History and Contaminants of Potential Concern ..................................................... 10 4.5. Previous Investigations ............................................................................................................... 11 4.6. Identification of Areas of Potential Concern ................................................................................ 11 5. ABBREVIATED PRELIMINARY ASSESSMENT/FIELD SCREENING ............................................... 13 5.1. Vat Water and Vat Soil/Sludge Sampling ................................................................................... 13 5.2. Surface and Shallow Subsurface Soil Sample Collection and Analytical Results ...................... 14 5.2.1. XRF Analytical Results ........................................................................................................ 14 5.2.2. Verification of Screening Level Risk Assessment Results .................................................. 14 5.2.3. Fixed Laboratory Analytical Results .................................................................................... 15 5.2.4. Further Evaluation of the Soil to Groundwater Pathway ..................................................... 16 5.3. Groundwater and Subsurface Soil Sample Collection and Analytical Results ........................... 16 5.3.1. Subsurface Soil Sample Collection and Analytical Results ................................................ 17 5.3.2. Groundwater Sample Collection and Analytical Results ..................................................... 18 5.4. Surface Water and Sediment Sample Collection and Analysis .................................................. 18 5.5. Screening Level Risk Assessment Summary ............................................................................. 18 5.5.1. Field Screening Level Risk Assessment ............................................................................. 18 5.5.2. Fixed Laboratory Results Screening Level Risk Assessment ............................................ 18 CDVMP Site Investigation at the Cattle Head CDV, Ozark National Forest (Update) Page i Task Order No. AG-43ZP-D-15-0007 March 2019 TABLE OF CONTENTS 6. FOCUSED SITE INVESTIGATION ..................................................................................................... 20 7. FOLLOW-ON SOIL SAMPLING .......................................................................................................... 21 7.1. Follow-on Soil Sampling Activities and Results .......................................................................... 21 8. QUALITY ASSURANCE AND QUALITY CONTROL SUMMARY ....................................................... 23 8.1. XRF Analysis Quality Assurance/Quality Control Samples ........................................................ 23 8.2. XRF Data Comparability and Usability ........................................................................................ 25 8.3. Evaluation of XRF Interferences ................................................................................................. 26 8.4. Fixed Laboratory Analysis Quality Assurance/Quality Control Samples .................................... 28 8.5. Data Validation ............................................................................................................................ 29 8.5.1. Field Data Validation ........................................................................................................... 29 8.5.2. Laboratory Data Validation .................................................................................................. 29 8.5.3. SVOC Resampling .............................................................................................................. 30 8.6. Deviations from the Sampling and Analysis Plan ....................................................................... 30 9. STREAMLINED RISK ASSESSMENT ................................................................................................ 31 9.1. Human Health Risk Assessment ................................................................................................. 31 9.1.1. Data Evaluation ....................................................................................................................... 32 9.1.1.1. Selection of Data for Use in the Risk Assessment .......................................................... 32 9.1.1.2. Selection of Contaminants of Potential Concern (COPCs) ............................................. 32 9.1.2. Exposure Assessment ........................................................................................................ 35 9.1.2.1. Exposure Scenarios ........................................................................................................ 35 9.1.2.2. Exposure Point Concentrations (EPCs) .......................................................................... 35 9.1.2.3. Calculation of Dermal and Ingestion Exposures to Toxaphene in Soils ......................... 35 9.1.3. Toxicity Assessment ........................................................................................................... 36 9.1.3.1. Non-Carcinogenic Contaminants .................................................................................... 36 9.1.3.2. Carcinogenic Contaminants ............................................................................................ 36 9.1.4. Human Health Risk Characterization .................................................................................. 36 9.1.4.1. Cancer Risks ................................................................................................................... 36 9.1.4.2. Non-Carcinogenic Risks .................................................................................................. 37 9.1.4.3. Radiological Risks ........................................................................................................... 37 9.1.4.4. Human Health Risk Summary ......................................................................................... 38 9.2. Ecological Risk Assessment ....................................................................................................... 38 9.2.1. Problem Formulation ........................................................................................................... 38 CDVMP Site Investigation at the Cattle Head CDV, Ozark National Forest (Update) Page ii Task Order No. AG-43ZP-D-15-0007 March 2019 TABLE OF CONTENTS 9.2.1.1. Selection of Ecological COPCs ....................................................................................... 39 9.2.1.2. Identification of Ecological Exposure Scenarios ............................................................. 39 9.2.2. Ecological Exposure ............................................................................................................ 39 9.2.3. Toxicity Assessment ........................................................................................................... 40 9.2.4. Ecological Risk Characterization ......................................................................................... 40 10. SUMMARY AND CONCLUSIONS ................................................................................................... 42