Alkali Lake Disposal Site Expanded Site Inspection Report Alkali Lake, Oregon March 2011 Prepared for: UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 1200 Sixth Avenue, Mail Stop ECL-112 Seattle, Washington 98101 Prepared by: ECOLOGY AND ENVIRONMENT, INC. 720 Third Avenue, Suite 1700 Seattle, Washington 98104 able of Contents T Section Page 1 Introduction ...............................................................................1-1 2 Site Background........................................................................2-1 2.1 Site Location.................................................................................................... 2-1 2.2 Site Description................................................................................................ 2-1 2.3 Site Ownership History .................................................................................... 2-2 2.4 Historical Site Operations ................................................................................ 2-3 2.4.1 Mining 2-3 2.4.2 Central Oregon Gunnery Range........................................................... 2-3 2.4.3 Chemical Waste Disposal Area............................................................ 2-4 2.5 Source Characteristics.......................................................................................... 2-6 2.5.1 Chemical Waste Disposal Area............................................................ 2-6 2.5.2 North Depression.................................................................................. 2-7 2.5.3 Drum Mound........................................................................................ 2-7 2.5.4 Soil Incorporation/Test Areas .............................................................. 2-8 2.6 Previous Investigations.................................................................................... 2-8 2.6.1 1969 to 1971 Geologic Investigation ................................................... 2-8 2.6.2 September 1973 Drum Condition and Leakage Survey....................... 2-9 2.6.3 October 1976 ODEQ Drum Sampling ................................................. 2-9 2.6.4 November 1976 Alkali Lake Task Force ........................................... 2-10 2.6.5 ODEQ Monitoring Well Installation.................................................. 2-11 2.6.6 ODEQ Site Monitoring ...................................................................... 2-11 2.6.7 1986 Final Report for Alkali Lake Chemical Disposal Site, Alkali Lake, Oregon, National Dioxin Study..................................... 2-12 2.6.7.1 Areas 1 and 2 Sampling ....................................................... 2-12 2.6.7.2 Area 3 Sampling .................................................................. 2-13 2.6.7.3 Test Plot Areas 1 and 2 ........................................................ 2-13 2.6.7.4 Domestic Well Sampling ..................................................... 2-14 2.6.8 1987 Tire 2A Dioxin Investigation .................................................... 2-14 2.6.9 1991 Phase I Remedial Investigation................................................. 2-14 2.6.10 1993 Technical Report for the Alkali Lake Ecological Assessment Phase I Reconnaissance.................................................. 2-15 2.6.11 January 1993 Analysis of Surface Water Flooding at the CWDA and Alkali Lake .................................................................................. 2-16 2.6.12 Ground Water Monitoring Well Installation...................................... 2-16 2.6.13 October 2001 ODEQ Soil Incorporation and Test Plot Sampling ..... 2-17 10:\STARTDOC\TDD NUMBER\SXXXX iii Table of Contents (Cont.) Section Page 2.6.14 July 2005 Risk Assessment................................................................ 2-18 2.6.15 April 2007 Record of Decision .......................................................... 2-19 2.6.16 September 2007 Final Site Inspection Report, Central Oregon Gunnery Range................................................................................... 2-20 2.6.17 Well Abandonment............................................................................. 2-21 2.6.18 Continuous Site Monitoring............................................................... 2-21 2.7 Summary of ESI Investigation Locations ...................................................... 2-21 3 Field Activities and Analytical Protocol ..................................3-1 3.1 Sampling Methodology.................................................................................... 3-2 3.1.1 Ground Water Sampling....................................................................... 3-2 3.1.2 Sediment Sampling ................................................................................. 3-3 3.1.1.1 Field Screening Sediment Sampling ........................................ 3-3 3.1.1.2 Off-Site Fixed Laboratory Sediment Sampling ....................... 3-3 3.1.3 Surface Soil Sampling............................................................................. 3-4 3.1.4 Surface Water Sampling.......................................................................... 3-4 3.1.5 QA/QC Sampling .................................................................................... 3-5 3.2 Analytical Protocol........................................................................................... 3-5 3.3 Global Positioning System............................................................................... 3-6 3.4 Investigation-Derived Waste............................................................................ 3-6 4 Quality Assurance/ Quality Control.........................................4-1 4.1 Satisfaction of Data Quality Objectives........................................................... 4-1 4.2 QA/QC Samples............................................................................................... 4-1 4.3 Project-Specific Data Quality Objectives for Fixed Laboratory Samples ....... 4-2 4.1.1 Precision............................................................................................... 4-2 4.1.2 Accuracy............................................................................................... 4-2 4.1.3 Completeness ....................................................................................... 4-2 4.1.4 Representativeness ............................................................................... 4-2 4.1.5 Comparability....................................................................................... 4-2 4.2 Laboratory QA/QC Parameters........................................................................ 4-3 4.2.1 Holding Times/Temperatures/Sample Containers ............................... 4-3 4.2.2 Laboratory Blanks................................................................................ 4-3 4.3 Field and Fixed Laboratory Correlation........................................................... 4-3 4.4 Chlorinated Pesticide Analysis ........................................................................ 4-4 5 Analytical Results Reporting and Background Samples ......5-1 5.1 Analytical Results Evaluation Criteria............................................................. 5-1 5.1.1 Sample Results Reporting .................................................................... 5-1 5.2 Background Samples........................................................................................ 5-2 5.2.1 Background Ground Water Samples.................................................... 5-2 5.2.1.1 Sample Locations................................................................... 5-2 5.2.1.2 Sample Results....................................................................... 5-2 5.2.2 Background Surface Soil Samples ....................................................... 5-2 5.2.2.1 Sample Locations................................................................... 5-2 iv Alkali Lake Draft SI report 3-29-11.doc-03/29/11 Table of Contents (Cont.) Section Page 5.2.3.2 Sample Results....................................................................... 5-3 5.2.3 Background Sediment Samples............................................................ 5-3 5.2.3.1 Sample Locations................................................................... 5-3 5.2.3.2 Sample Results....................................................................... 5-3 6 Potential Sources......................................................................6-1 6.1 Chemical Waste Disposal Area........................................................................ 6-1 6.1.1 Sample Locations................................................................................. 6-1 6.1.2 Sample Results..................................................................................... 6-1 6.2 North Depression.............................................................................................. 6-2 6.2.1 Sample Locations................................................................................. 6-2 6.2.2 Sample Results..................................................................................... 6-2 6.3 Alkali Lake....................................................................................................... 6-2 6.3.1 Sample Locations................................................................................. 6-2 6.3.2 Sample Results..................................................................................... 6-2 6.4 Soil Incorporation Areas .................................................................................