2010-10-06_REVISION - M1977300 (3)

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10/4/10 TECHNICAL REVISION 14 ALLUVIAL SOURCE TERM CHARACTERIZATION PROJECT Cotter Corporation (N.S.L.) ("Cotter") would like to conduct a comprehensive study for the identification and characterization of any source term materials within the alluvial fill. This study will include an analysis of the "toxic forming" properties of any such source term materials along with an assessment of their disposal in the mine workings from which they originated (via the Minnesota portal). Depending on the outcome of the assessment, Cotter will submit an additional Technical Revision request to Division of Reclamation, Mining and Safety ("DRMS") for approval to dispose of such source term materials in the Minnesota portal, or will propose alternatives for the disposal of that material. This study will include the following components: 1. Assess water monitoring data from the recently re-initiated stream water sampling stations along Ralston Creek adjacent to the alluvial fill. Identify any regions of alluvial fill that may have greater influence on uranium loading to the creek. These areas may represent locations of priority interest for depth profile soil sampling. 2. Examine the results of Item 1 above along with historical documents and previous gamma survey data across the surface of the alluvial fill to select targeted locations for depth profile sampling in areas expected to have a potential for source term material, and which may have a greater impact on alluvial groundwater and surface water in the creek. 3. During the late summer or fall season when water tables are at their lowest level, use a backhoe to dig small trenches that provide access to the soil profile for in-situ gamma measurements and soil sampling at incremental depths. The expected length of each trench will be equivalent to the horizontal excavation reach of the backhoe (approximately 10 feet long). The expected width of each trench will be somewhat wider than the width of the backhoe bucket (about 3 feet wide). The expected depth will vary depending on depth to bedrock, the capacity of the backhoe, and other factors, but is generally expected in the range of 5 - 14 feet. Sampling increments within a given trench may vary depending on the results of gamma surveys along the trench walls, but should average 1 or 2 feet between samples unless signs of elevated materials with elevated source term characteristics are identified (in which case more closely spaced samples will be collected). With the ability to survey the trenches in- situ and obtain near real-time sampling results in the on-site screening laboratory, flexibility in depth increment selection and number of samples needed to meet project objectives is possible for this type of radiological survey. Take photos and document pertinent sampling information (e.g., date, sample ID, sample depth, GPS reading for location, general descriptions and observations). 4. As samples are collected, analyze them in a small on-site soils laboratory for Ra-226 content as described in the decommissioning plan for Radioactive Materials License CO-369-03.