This Supplemental EIS evaluates the completion of the Chemistry and Metallurgy Research Building Replacement (CMRR) Project, which consists of constructing the nuclear facility portion (CMRR-NF) at Los Alamos National Laboratory (LANL). The CMRR Project provides the analytical chemistry and materials characterization capabilities currently or previously performed in the existing Chemistry and Metallurgy Research (CMR) Building. Because of recent detailed site geotechnical investigations, certain aspects of the CMRR-NF project have changed resulting in change to the environmental impacts.