SELECTION OF POTENTIAL SOIL PLOWING EXPERIMENTAL AREAS ON THE ISLAND OF JANET DOE/ERSP TECH NOTE NO.9.0 DATED: 12 May 1978 AUTHOR: Dale H. Denham, LLL Su mmary Three 25m x 75m areas, including eight stake locations on a 25m grid, were selected on the island of Janet as potential sites to conduct one or more plowing experiments. The purpose of said plowing experiment(s) was stated in the 15 May TWX from FCDNA (Albuquerque) to USDOE (Las Vegas) as follows: "To evaluate the effectiveness of plowing in dose reduction for Food Gathering, Agricultural and Potential Residence islands". Implicit in that definition is that plowing may provide an alternative to or be used to supplement soil removal. Janet was chosen since it met all of the island "types" listed in the above definition and is one of the most important islands for cleanup. The three areas so chosen include two in the NW sector and one in the SW sector (see Figure B~9-1). One location is about 350 m from the Item Ground Zero (GZ), a second is about 625 m from both the Item and Easy/X-ray GZ areas, and the third is about 850 m from the Easy/X-ray GZ. All three areas were selected because they exhibited relatively uniform and significant surface contamination levels (30-70 pCi/g TRU, based on previous IMP surveys and surface soil sampling), and they were relatively free of major debris or vegetation. Soil samples were collected at the eight stake locations in each experimental plot (designated as Plow X-l, X-2 and X-3) for a total of 120 samples per plot (16 additional samples were collected in Plow X-] because the profile samples were collected to a depth of 120 em rather than 100 em as for the other plots). Plastic petri dishes were filled with soil for approximately haif of the samples. The soil in these petri_ dishes was then categorized into several soil types and then gamma-scanned with the IMP for both 24lam and 137¢s activity levels. Some samples from the Plow X-1 plot were processed through the laboratory. Preliminary results from the visual soil characterization and IMP screening indicate that all three plots exhibit similar data. The following conclusions are based on these preliminary observations: 1. The soil is basically in 3 layers: the top 20 to 40 em is mostly a brown sand and soil mixture with some vegetation (root matter) and small pebbles; the middle layer, ranging from about 30 to 60 em below the surface, is composed of a richer mixture of dark brown, moist soil and sand; and the 2. Average surface concentrations of 2414m were 30 pCi/g, 14 pCi/g, and 24 pCi/g in the X-l, X-2 and X-3 plots, respectively, corresponding to 100 pCi/g, 46 pCi/g and 80 pCi/g TRU (using the computed TRU/Am ratio of 3.3). 3. The 241Am concentration decreased approximately exponentially with depth below the surface; an order of magnitude decrease was observed in the first 15 to 20 em. 4. Average surface concentrations of 137%Cs were 340 pCi/g, 86 pCi/g and 270 pCi/g, in the X-1 to X-3 plots, respectively. B44 The 138%cs concentrations also decreased with depth, but at a less pronounced rate than for Am. 6. The highest 137Cs concentrations were observed in the richest soil fractions. Apparently no 241 am or 187Cs (above their respective MDLs of 1 to 2 pCi/g and 8 to 10 pCi/g, respectively) have leached through to the coral sand layer about 60 em below grade. B-9-1 - <<. bottom layer (60 to 120 em below grade) is mostly coral sand and pebbles interspersed with some brown and gray sand (Figure B-¥-2).