B. bee rg ERE Se ceva _ METHOD 1. Plutonium concentration contours (isopleths) will be developed for each of the northern islands which contain high-concentration regions (Enclosure 3), ‘and any other-northern islands which might be shown during Cleanup to have high concentrations. (In general, the confirmatory data obtained from low-concentration regions will not be sufficient to structure meaningful _isopleths.) The isopleths will be computed by the most advanced automatic ~ contouring method available at the time of Cleanup, and comparable to or exceeding the SURFACE II program described in Reference 5. The raw data “ to be contoured will consist of the Pu concentrations obtained during Cleanup by laboratory analysis of soil samples collected from within the areas under investigation. The concentration contours will be used for _ Yanking areas according to their cleanup requirements, e.g.-~mandatory “ € >400 pCi/g), negotiable (between 40-400 pCi/g), or no cleanup ( <40 pCi/g). . When the area within an isopleth becomes programmed for Cleanup, then the "goil therein will be removed in successive layers until samples collected from the residual surface show Pu concentration to be as low as is reasonably achievable (<40 pCi/g). Ct neg Sea ~UTeESAS LL ———— . eo€ t . a wea : ee . . wena me dies ate ae : - sae at vtec AB ¢ 2 : ne ' 2. It is highly probable that a minimum of ten ‘thousand ‘soil,‘samples will require analysis in order to adequately define the regions deserving soil cleanup and to verify that all the necessary Pu-contaminated soil has been removed. Prompt Pu analyses are necessary to expedite Cleanup. The quantitative assay of soil for Pu at the concentration levels of interest to Cleanup, however, is laborious by any method. Nuclear radiation detection methods are essential as the quantity of Pu amounts to only a few parts per trillion by weight; however, the nuclear methods are made difficult becaus_ Tu is predominantly an alpha emitter. For the most precise nuclear methods, the Pu must be separated from its soil matrix prior to alpha counting, and that extends the time per analysis. Oe ve Lace. Late. 7 reactive wt ~ 3. To achieve the necessary accuracy, and speed of ‘analysis, ‘the. Cleanup will have_an on-site Radiological Laboratory ca of determinin Pu in soil by a combined solvent extraction-liquid scintillation method Vevy modeled after that of Reference 6. Should more suitad aborato.y method 1¢¢". . become available prior to or duping Cleanup, it would be emp loye it feasible... “fey To avoid the possibility that data obtained from the "field lab" is later er questioned, an adequate fraction of the on-site analyses will be repeated for verification ofaccuracyabtheUSAF/McClellan Central Laboratory (USAF/MCL) *<*° which has an established reputation for performing high-quality radiochemical analyses of environmental samples. a 4. After decisions have been made that the soil in an area deserves to be excised, and engineers begin removing the soil, a less accurate analysis method is suitable to monitor the progress of soil removal if the method provides "instant" results. The alpha scintillation counting of soil without any Pu separation, as reported in Reference 7, appears to be a relatively fast . 8 ete “EePeayTaet hE Segome ” eet, TAs _ . ON = varsISET eenSree meee oan — ORT se e veda 8 oer ver ‘ ere, 7 ~ ° rstat ass . hat tq “ . tate toy wa Be j we . ‘ .