Dr James L. Liverman -~2- August 17, 1977 Although the reviewers identified alternatives that may be preferable, there was unanimous eagreer-+nt that the planned emplacement of plutonium contaminated soil and debris ia concrete in the Cactus Crater does not impose unacceptable environuental and health risks. Review of Plans for Cleanup of Enewetak Atoll A. Criteria for removal of contaminated soil The reviewers considered the criteria for the relocation of approximately 10 Ci of plutonium from dispersed locations in the terrestrial environment to a central location in the Cactus Crater on Runit Island. The reviewers concurred with the 40 pCi Pu/e soil value adopted in the Environmental Impact Statement as a minimal action level and with 400 pCi/g as the mandatory cleanup level. Using the assumptions in the EIS the reviewers estimated that the lung dose resulting from lifetime inhalation of air containing an equivalent concentration (100 ye soil/m? air or & £CL Pu/r?) would be approximately 0.01 rem/year, or 1 mrad/year, assuming a quality factor of 10. This ccmpares with the proposed EPA federal guidance value of 1 mrad/year tc the lung from transuranic elements in the environment. The reviewers believe that lung doses from inhaled plutonium will be considerably less than this for persons living and working on the Atoll because of the small land area which minimizes buildup of plutonium concentrations in the air and because of the conservative assumptions used in estimating dese; e.g., all contaminated soil was considered respirable, the concentration of soil in air was maintained constantly at the 100 ye/m3 level, etc. The reviewers recommend that more specific guidance for application of the criteria at plutonium levels between “49 and 400 pCi/g te developed for the Task Group Commander.