DOCUMENT DOES NOT CONTAIN ECI — Zz + attetie wnLEE 1mHoro” Project Number acific Northwest Laboratories April 18, 1978 To Bill Bair From Dick Gilbert Det Subject Suggested reconmendations to DOE on the Basis of the April 13-14, 1978 Meeting of the Advisory Group on Cleanup of Enewetak Atoll in Las Vegas. Based on my observations during the subject meeting and my phone conversation with Madaline Barnes (statistician for cleanup effort) on April 17, the following items seem to be important to point out to DOE. Averaging I see no compelling reason to alter the previously agreed upon plan to consider each 1/4 or 1/2 hectare area separately for cleanup. I see no advantage to using an "average island" soil concentration for making cleanup decisions. ‘Apparently, the concept of an average island concentration arose during the April 13-14 meeting since Bill Robison, et al had used the term in obtaining dose estimates for the Enewetak Atoll. The term was perhaps inappropriate because these authors did not use actual soil concentration data for their computations. Instead dose estimates were obtained for a series of hypothetical "average island" soil concentrations. There are a number of methods that could be used for using actual soil data to make dose assessments. Compute the dose on the basis of highest estimated soil concentration AYOLISOd 34 for any unit (of 1/4 or 1/2 hectare size) on the island. This method could result in a very conservative dose estimate if most units on the island had much lower concentrations than the highest unit. Average al] the unit (1/4 or 1/2 hectare) average soil concentrations 7 NNe¢ } paysaviyl NO!L937109 SPYy) ST PL6i liedy yameug ‘ON XOF G&IS we A on an island and use this grand average to estimate potential dose. This method weights all units equally, even though some units would undoubtedly have greater utilization by inhabitants than other units. ' 3. A conservative approach would be to use the cleanup criteria desig- nation for the island (40, 100, or 400 pCi/g, for village, agricultural, or picnic islands, respectively). Dose estimates for this option were obtained by Robison, et al. in their dose assessment paper presented to us at the meetings. Conservative dose estimates are likely since most units have average soil concentrations much below these cleanup criteria. §4—-1900-00!1 (3-71)