Interim Baseline Radiological Investigation Report
November 14, 2012
Bear Lodge Project, for Rare Element Resources, Inc.
Rev.1
18
In accordance with the SAP, the baseline soil samples were collected from 0-15 cm and analyzed
by Energy Laboratories in Casper, Wyoming for Ra-226, radium-228 (Ra-228), natural uranium
(U-nat), and isotopic thorium, the latter consisting of thorium-228 (Th-228), thorium-230 (Th-
230), thorium-232 (Th-232). Corresponding analytical methods, all published by the U.S.
Environmental Protection Agency (EPA), are summarized below:
Ra-226, Ra-228
EPA M901.1
Th-228, Th-230, Th-232
EPA M908.0
U-Nat
EPA M6020 Inductively Coupled-Mass
Spectroscopy
4.2
Surface Soil Ra-226 Results
The following discussion is based largely upon the results and spatial distributions reflected in
the supporting figures and tabular summaries.
Table 4.2 documents the results of the soil sampling. Table 4.3 presents the resulting summary
statistics for radionuclide concentrations in surface soil.
The distribution of Ra-226 concentrations in the random samples was subject to the same
probability distribution tests as those described in Section 3.2.1. The overall Ra-226 distribution
characteristics are non-parametric. Eight of the results are reported by the external laboratory as
0.0 picocuries per gram (pCi/g). These results were assigned a value of 0.3 pCi/g --the associated
reporting limit-- for the calculations in Table 4.3.
The median of the surface soil Ra-226 data set is 1.3 pCi/g, with a corresponding IQR of 0.7 (1.7
less 1.0 pCi/g).
Although most of the site exhibits Ra-226 concentrations less than 2.5 pCi/g, areas in the known
mineralized portions of the Project exhibit elevated concentrations of radionuclides.
