Human and Ecological Risk Assessment - Earthjustice

Section 4.0Risk CharacterizationTable 4-23. Summary of 90th Percentile Full-Scale CCW Ecological Risk Results:Groundwater-to-Surface-Water Pathway, Sediment Receptors aChemicalLandfillsUnlined Units90th Percentile Ecological HQClay-LinedUnitsComposite-Lined UnitsExposurePathwayReceptorLead 58 1 1E-06 direct contact aquatic biotaArsenic (III) 11 3 5E-04 ingestion river otterCadmium 5 1 6E-05 direct contact aquatic biotaAntimony 2 0.5 7E-05 direct contact aquatic biotaMolybdenum 0.1 0.03 2E-05 direct contact aquatic biotaBarium 0.006 6e-04 0 direct contact aquatic biotaSurface ImpoundmentsLead 311 58 4 direct contact aquatic biotaArsenic (III) 127 55 31 ingestion river otterCadmium 30 9 2 direct contact aquatic biotaMolybdenum 0.9 0.3 0.1 direct contact aquatic biotaBarium 0.008 0.004 0.002 direct contact aquatic biotaaZero results indicate that contaminant infiltration rates were too small for the contaminant plume toreach the receptor during the 10,000 year period of the analysis.Table 4-24. Summary of 50th Percentile Full-Scale CCW Ecological Risk Results:Groundwater-to-Surface-Water Pathway, Sediment Receptors aChemicalLandfillsUnlined Units50th Percentile Ecological HQClay-LinedUnitsComposite-Lined UnitsExposurePathwayReceptorLead 6E-05 9E-08 0 ingestion spotted sandpiperArsenic (III) 4E-03 0.002 0 ingestion spotted sandpiperCadmium 5E-04 2E-04 0 direct contact sediment biotaAntimony 3E-04 1E-04 0 direct contact sediment biotaMolybdenum 5E-05 3E-05 0 ingestion spotted sandpiperBarium 3E-13 8E-15 0 ingestion spotted sandpiperSurface ImpoundmentsLead 0.1 0.001 0 ingestion spotted sandpiperArsenic (III) 0.4 0.02 4E-09 ingestion spotted sandpiperCadmium 0.02 0.0007 0 direct contact sediment biotaMolybdenum 0.004 0.0002 2E-08 ingestion spotted sandpiperBarium 1E-05 1E-06 0 ingestion spotted sandpiperaZero results indicate that contaminant infiltration rates were too small for the contaminant plume toreach the receptor during the 10,000 year period of the analysis.April 2010–Draft EPA document. 4-31