Human and Ecological Risk Assessment - Earthjustice

CCWTable of ContentsTable of ContentsExecutive Summary .................................................................................................................. ES-11.0 Introduction ...................................................................................................................... 1-11.1 Background .......................................................................................................... 1-11.2 Purpose and Scope of the Risk Assessment ......................................................... 1-21.3 Overview of Risk Assessment Methodology ....................................................... 1-21.3.1 Contaminant Sources ............................................................................... 1-21.3.2 Exposure Pathways .................................................................................. 1-31.3.3 Risk Levels............................................................................................... 1-31.3.4 Methodology ............................................................................................ 1-31.3.5 Waste Management Scenarios Addressed ............................................... 1-51.3.6 Modeling Approach ................................................................................. 1-61.4 Document Organization ....................................................................................... 1-72.0 Problem Formulation ....................................................................................................... 2-12.1 Source Characterization ....................................................................................... 2-12.1.1 Identification of Waste Types, Constituents, and ExposurePathways .................................................................................................. 2-22.1.2 Waste Management Scenarios ................................................................. 2-52.2 Conceptual Model ................................................................................................ 2-62.2.1 Conceptual Site Model ............................................................................. 2-72.2.2 Conceptual Site Layouts .......................................................................... 2-92.3 Screening Analysis............................................................................................. 2-122.4 Full-Scale Risk Assessment ............................................................................... 2-122.4.1 Data Collection ...................................................................................... 2-132.4.2 Model Implementation ........................................................................... 2-142.4.3 Exposure Assessment............................................................................. 2-152.4.4 Risk Estimation ...................................................................................... 2-163.0 Analysis............................................................................................................................ 3-13.1 Toxicity Assessment ............................................................................................ 3-33.1.1 Human Health Benchmarks ..................................................................... 3-33.1.2 Ecological Benchmarks ........................................................................... 3-63.2 Constituent Screening .......................................................................................... 3-83.2.1 Waste Constituent Concentrations ........................................................... 3-83.2.2 Media-Specific Exposure Concentrations for Screening ......................... 3-93.2.3 Screening Methodology ........................................................................... 3-93.2.4 Screening Results ................................................................................... 3-113.3 Full-Scale Modeling Approach .......................................................................... 3-133.3.1 Spatial and Temporal Framework .......................................................... 3-133.3.2 Probabilistic Approach........................................................................... 3-153.3.3 Implementation of Probabilistic Approach ............................................ 3-173.4 Landfill Model ................................................................................................... 3-193.4.1 Conceptual Model .................................................................................. 3-203.4.2 Modeling Approach and Assumptions................................................... 3-21April 2010–Draft EPA document.v