A Modeling Protocol for a level 1 and level 2 risk assessment must include identification of exposure locations and reporting of Risk Based Concentrations (RBCs) that will be used in the analysis. Because level 1 and level 2 risk assessments do not require separate risk assessment work plans, the Modeling Protocol must include all exposure scenario assumptions made before submission of the final risk assessment.
A level 3 or level 4 risk assessment requires both a Modeling Protocol and a Risk Assessment Work Plan. Because there is significant overlap between modeling and risk assessment, specifically in the receptor grid and exposure location assignment, a crosswalk of all receptor coordinates and exposure locations should be submitted as an electronic spreadsheet at the modeling protocol stage -- fields should include, at a minimum, the following information for each modeling receptor: identification, UTM Northing, UTM Easting, and exposure classification. All gridded modeling receptors should be included in the crosswalk, including roadways and railways where risk may ultimately not be calculated. Information regarding RBCs and risk calculations are part of the Risk Assessment Work Plan.