PLOWING EXPERIMENT: ON-SITE REPORT*
DOE/ERSP TECH NOTE NO. 9,1
AUTHORS:
DATED: August 1978
D. Denham, LLL
M. Barnes, DRI
T. Crites, LLL
Introduction
The purpose of the plowing experiment was stated in the 15 May TWX from FCDNA (Albuquerque)
to U.S. DOE (Las Vegas) as follows: "To evaluate the effectiveness of plowing in dose reduction for
food gathering, agricultural, and potential residence islands." A planning meeting was held at
Enewetak (11 May 1978) to more fully define the JTG requirements of such an experiment. Three
50-m x 100-m areas were selected on the island of Janet as potential sites for the experiment
(Figure B-9-1). These were chosen because they exhibited relatively uniform and significant surface
contamination levels (30-70 pCi/g TRU) and were relatively free of major debris or vegetation. A
detailed report on these areas was prepared as Tech Note 9.0, part of which is included in the
following section.
Preliminary Work
l.
Site Selection
a.
Surface Measurements
Standard IMP survey measurements were made on a 25-m grid in each of the three
plots considered. Results of this surface measurement of 241 am are:
Plow X Plot
Average
Minimum
Maximum
1
20.8
14.7
30.6
2
8.8
6.5
11.2
3
14.6
11.7
18.2
Surface (2.5 em) soil samples were collected on the A, B, C, and D composite plan (See
Figure A-4-1) at each of the IMPed points (24 grid locations). Petri dish samples were
made of these composites and screened with the IMP detector on Ursula.
of the IMP screening of those samples are:
Plow X Plot
b.
Average values
241Am (pCi/g)
l
32.2
2
14.0
3
24,1
Profile Samples
To aid in site selection, soil profile samples were taken at each of the three plot
locations. Holes were dug to a nominal depth of 120 to 140 em at several points in each
plot. Sidewall sa mples were taken with a standard tool (5 em deep by 10 em square) and
IMP sereened for
*41Am and 13%Cs content. The 241Am results are plotted in Figure
B-9-6. Soil profile observations are characterized in Figure B-9-2.
¥A modified version of this note by the same authors was published in the April 1980 issue of Health
Physics; "The Effect of Plowing on 241 4m Contamination in Sandy Soil," Health Physies 38, 699-703.
B-9-13