Interim Baseline Radiological Investigation Report in
Support of the Upton Rare Earth Processing Plant
November 15, 2012
16
4.0
BASELINE RADIOLOGICAL INVESTIGATION SOIL SAMPLING
This section presents the results of the baseline soil sampling conducted in June 2012. Section
4.1 summarizes the soil sampling field approach, scope, and analytes. Section 4.2 discusses the
results obtained for radium-226, the focus of the baseline soil sampling program. Section 4.3
addresses results for other radiological parameters. Section 4.5 discusses the correlation between
radium-226 and natural thorium concentrations in soil and gamma count rates. The laboratory
analytical reports for the soil analyses are provided in Appendix B.
4.1
Sampling Strategy and Approach
The soil sampling strategy for the Upton Project consisted of random sampling at the 16
locations shown in Figure 4.1, in accordance with the strategy in the SAP. The identifiers in
Figure 4.1 were truncated to facilitate presentation; e.g., Sample SS-05-SS-061412 was changed
to 5. Table 4.1 lists the coordinates of the sample locations. Radon flux measurements were
taken at five of the sample locations, as noted in Table 4.1.
The number and types of analytes for the surface soil samples were based on obtaining general
knowledge of the distribution of the primary long-lived radionuclides in the uranium and thorium
natural decay series. The sample locations were determined using Equation 4 of Section 2.3.3.4
in the SAP, which is:
2
>
cv
r
t
N
Where:
N = number of samples
t = the t-statistic (1.645)
r = 0.2, the relative fraction error, or the mean minus the true mean, divided by the true mean
cv = coefficient of variation, or the standard deviation of the population divided by the mean
The coefficient of variation (standard deviation/mean= 0.67) was determined from the gamma
survey data (see Table 3.1). In this case, N=16 samples, which were spaced on a systematic,
triangular grid with a random start location, using Visual Sampling Plan Version 6.2d.
