b.
During the in situ van measurements, areas will be selected where representative soil
samples will be taken. These soil samples will be transported to Enewetak for analysis by the
Radiochemistry Laboratory. The americium (Am) and plutonium (Pu) concentration data from these
soil samples will be used to complete the data chain for calculation of plutonium soil concentrations
from the in situ van measurements. A maximum of 100 soil samples may be sent to McClellan
Central Laboratory* for analysis during July/August, (results required by 30 August) depending upon
the availability of the Radiochemistry Laboratory on Enewetak presently scheduled to become
operational in August.
ec.
Soil sampling is an important part of the in situ van operation since the Pu and Am data
derived from the soil samples provides the basic van detector calibration. For this reason, careful
sampling procedures will be used to assure the validity and accuracy of surface concentration data,
and of the gradient of concentration with depth.
d.
After all measurement locations have been visited and data acquired, a complete set of
data for that island will be sent to the Data Reduction Trailer. These data, together with the Am
and Pu data from the soil samples, will be used to generate isopleth map overlays showing plutonium
soil concentration contours. Soil sample analysis may take three to four days and the basic data
processing is expected to take one to two days.
e.
The first plutonium contours will be used as a guide to determine which areas need to be
cleared further for a more detailed survey grid. After this clearing is complete and a new grid
surveyed in to fit the area, the in situ van will be used to provide a more detailed set of plutonium
concentration contours. These contours will then be used to direct soil removal operations.
f.
After the initial soil removal, the in situ van will re-survey the removal area. Analysis of
additional soil samples may be required and will be done by the Radiochemistry Laboratory at
Enewetak. This reevaluation will result in a new set of plutonium soil concentration contours that
will be used to guide additional soil removal operations. Upon completion of the final soil lift, the in
situ van will be used to document the then existing concentrations and a final set of plutonium
concentration contours will be drawn. It is important that the documentation, which will be
essential to ERDA certification, be referenced to permanent coordinates. **
gs
The concept of phased operations presents the opportunity to make an initial gross survey
of the islands to identify those with the highest probability of soil removal. These data will greatly
assist in developing working estimates of soil to be removed.
_
hh.
An ERDA aerial survey system will be fielded as early as possible {i.e., shipped in
i.
The first van will be shipped approximately 1 July and become operational in mid-July, a
mid-June and operational shortly thereafter). This aerial system would proceed to survey the islands
where soil removalpossibilities exist.
second van, will be operational in August and both will commence with the fine surveys.
By the
August/September time frame, sufficient fine surveys can be completed to allow soil removal to
begin in the planned mid-November time frame.*** As noted in 3.b above, the initial soil samples
for van calibrations will be sent to McClellan AFB for analysis, The Radiochemistry Laboratory is
expected to become operational on Enewetak in August.
je
A third van is expected to be on Enewetak at the end of September. This van is intended
as an operating spare replacement for the operating vans.
*No samples were sent to this laboratory.
**Reference points were not recovered or established on some islands, so this aspect of the
documentation is incomplete.
***Soil removal operations did not start in November.