Letter to J L Liverman, Subject: Plans for the Cleanup of Enewetak Atoll (Encl; Plans for Cleanup)

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for Environment md Safety In response to your request of August 11, 1977, plans for the cleanup of Enewetak Atoll were reviewed at a meeting at the Nevada Operations Office, August 15-17, 1977. A list of participants in the review is Prior to the meeting, the reviewers were provided copies of documents relative to the development of cleanup criteria and preparation of the EIS. Supplementing these were briefings by Joe Deal, To-my McCraw, Roger Ray, and members of the Staff of the Defense Nuclear and Eajor General Shedd and Colonel Header described operational plans for soil cleenup and crater disposal. In addition, Mr. M. Gates, Manager of the Nevada Operations Office, met with the.reviewers and discussed points he raised in his let~er to YOU* The reviewers addrzssed two primary issues: The criteria for cleanup of the islands contaminated with “ne plan for disposal of plutonium contaminated soil and other radioactivity cont~~inated debris i.nthe Cactus Crater. Several other re13ted issues were addressed during the discu~sion.

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Although the rev~ewers identified alternatives that may be preferable, there was uzz=~mm agrezr.nt that zhe planned emplacement of plutonium contaminated soil and debriz ia concrete in the Cactus Crater does not impose unacceptable environmental and health risks. A. Criteria for removal of contamina~ed 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 Crauer on Runit Island. The reviewers concurred with the 40 pCi Pti/gsoil value adopted in the hvironmeutal Inpact Statement as a minimlalaction lel’eland with 400 pCi/g as the mandatory cieanup level. Using the assumptions in the EIS the reviewers esti~titedthat the lung dose resulting frGm lifetime inhalation of air containing 4 fci Pu/r~.3jwould be approximately 0.01 rem/year) cm 1 mrad/yearj assuming a quality factor of 10. TMs ccmpares with the proposed EPA federal guidance eilementsin the environment. The reviewers believe that lung doses from inhaled plutonium will be consider~bly less than th~s for persons living and work~ikg on the Atoll because of the small land trations in the air and becaus~ of the comenative assumptions used in estimating dcse; e.g., all contaminated soil was considered respirable, the constantly at the 100 pe!m~ level, etc. The reviewers recommend that more specific guidance

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The !k’:ircnmentalImpact Statement indicates that 90sr and 137cs in the soil and the uptake by plants is the major problem which will limit the occupancy and utilization of certain islands of the Atoll. Certain sc,ilamendments that have been shown to significantly decrease the uptake of these radionuclides may be useful for hastening the rehabilitation of the Atoll. ... B. Disposal of plutonium-contaminated soil and debris in the Cactus Crater In examining the question of disposal of contaminated soil and debris, the reviewers considered potential human health effects, future maintenance and monitoring requirements, retrievability, potential restrictions on access to Runit Island, implications and risk of quantities of debris, and engineering problems. Weighed against these considerations the reviewers agreed that the planned emplacement of concreteencased plutonium-contaminated soil and debris in the Cactus Crater would not in itself impose unacceptable human health risks. The method could result in the gradual release of this plutonium to the marine environment; this would be in addition to the 1500 Ci already in the lagoon sediment. However, for the worst case in wh~.ch10 Ci Pu is added to the Crater below the water level, the local lagoon water plutonium concentration would not increase more than by a factor of two. This could lead to an increased dose of a few mrem per year to a person who obtained all of his food from the local marine environment. Several alternate disposal schemes, while not . significantly influencing the health risk prospects, to chzn~c dlspasal plzns at this late date, the reviewers believe you should be aware of the possible advantages of other methods.

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Ocean dumpingias considered to be the preferred quantities-of soii and debris are high (75,000225,000 yds3), the plutonium inventory is estimated to be only in the order of 20 Ci, an insiguiflcant amount to dump into the PacifSc Oceac compared to that which is already present in the ocean from weapons test fallout. Presently 3-4 Ci is transported from the waters of the lagoon to the open ocean each year. Ke understand that EPA interprets PL 92-532 to effectively prohibit ocean dumping by the U.S. Rowever, the U.S. has contributed technical guidance and is signatory to the international agreement on the dumping of radionuclj.desin the ccean under the London Convention which “allows” dumping of much larger quantities than 20 Ci of plutonium. Advantages of deq ocean duxping include the removal of the plutonium completely from the Atoll environment and the elimination of the need for any future monitoring and maintenance. Eiowever,the EIS would probably have to be reopened and an oceanographic survey Lagoon dumping as an acceptable alternate to ocean dumping minimizes international ramifications. Since soil would be slowly dispensed to the lagoon during the cleanup and only a small fcaction of the bound plutonium will be remobilized, the actual impact on the lagoon water concentration will be slight. It can be demonstrated by computation that less than 0.01% of the plutonium would be zenobilized to the . solution phase during dispasal to che lagoon. The majority of material would settle to the floor of the lagoon. Concentrations of plutonium in aquatic organisms might increase, but since the residence time for sea water in the lap,oonis about 150 days, the concentrations would shortly be reduced to . ambient levels. Agzin, the EIS would have to be Federal ageucies and the Trust Territory.

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‘ccncretecover would hzve the lsast inneciiate impact on the local marine environment in that remobilf.zationof the radionuclides from the. soil to the groundwater and eventually to maximize potential occupational exposures during the cleanup operation. Terrestrial disposal by covering the existing contaminated areas on Runft with contaminated soil removed from other islands, but without concrete cover, was also considered. This plutonium on R-unit,but might require quarantine. Roth terrestrial disposal methods would allow retrieval of the plutonium. Both wouid require reopening of the EIS. Other methods for disposal of plutonium were proposed. One interesting possibility is the application of mining and tilling techn~ques to separate plutonium from the soil of Enewetak Atoll. The reviewers were not aware of this having been explored. While such a technique could not be available for applicatio~ to Enewetak Atoll.,it might be useful at other sites in the C. Future ERDA Commitments at Enewetak Atoll According to the Environmental Impact Statement, ERDA @ committed to long-term monitoring the the Enewetak Atoll. Planning for this responsibility appears to be incomplete. reviewers offer the following su~gestions: The environmental monitorin~ pragrm should be as &8tfmating radia5iGs doses to the inhabitants of Any actlvltles carried olltby individuals other thr.

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3. During the next three years a study of %&suspension of plutonim from soils in - circumstances typical of those that will occur when the islaridsare reinhabited should be conducted. It is emphasized that this should not be a study of resuspension associated with cleanup activity per se. Information applicable to the Enewetak people will be invaluable in improving estimates of radiation dose to h-n beings returning to the islands and will assist fn reaching decisions about future use of specific islands. 4. The EPA regards the crater disposal method as temporary storage. Under this view, ~?ir4tenanceof the concrete structure may be required. The Defense Nuclear Agency regards this’method as permanent disposal which would imply no maintenance. This could lead to uncertainties of responsibility for future activities at the crater site. 5. A programtic effort must be initiated to communicate to the Enewetalcpeople the nature of the risks to which they will be exposed. The potential risks associated tith living and visiting the various islands must be made comprehensible to the people from their perspective to insure their understanding the need for restricted access to Runit, etc. D. Concern for incomplete cleanup Yhe reviewers were concerned that the cleanup program, as defj.nedin che FIS, could be terninatcd . before completion if the fu~tisand other resources due to underestimates of the r~gnitude of the amount of soil that has to be renmved.

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L’nConclusion it should be emphasized that.only the adequacy of the criteria and disposal methods were reviewed and that the operational Dlans for assuring implementations of the criter~a were not examined

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Director, Heaiilnand Safety Laboratory Directorl Inhalation Toxicology Research Institute Lovelace Foundation for Ikd.icalEducation and Research Section Leader for Marine Sciencest Environmental Sciences Division

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Assistant Director for Field Operations U. S. Energy Research and Development Administration AssistantManager for Environmeritand Safety Nevada Operations Office U. S. Energy Research and Development Administration . Office of the Assistant Administrator for Environment and Safety

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Kirtland AFB, Field Cornand Captain Ronald M. Spencert USA Nevada Operations Office