Laserfiche WebLink
COTTER CORPORATION (N.S.L.) <br />ALLUVIAL SOURCE TERM CHARACTERIZATION PROJECT <br />Cotter Corporation (N.S.L.) ("Cotter") would like to conduct a comprehensive study for the <br />identification and characterization of any source term materials within the alluvial fill. This <br />study will include an analysis of the "toxic forming" properties of any such source term <br />materials along with an assessment of their disposal in the mine workings from which they <br />originated (via the Minnesota portal). Depending on the outcome of the assessment, Cotter <br />will submit an additional Technical Revision request to Department of Reclamation, Mining <br />and Safety ("DRMS") for approval to dispose of such source term materials in the Minnesota <br />portal, or will propose alternatives for the disposal of that material. This study will include the <br />following components: <br />1. Assess water monitoring data from the recently re-initiated stream water sampling stations <br />along Ralston Creek adjacent to the alluvial fill. Identify any regions of alluvial fill that <br />may have greater influence on uranium loading to the creek. These areas may represent <br />locations of priority interest for depth profile soil sampling. <br />2. Examine the results of Item 1 above along with historical documents and previous gamma <br />survey data across the surface of the alluvial fill to select targeted locations for depth <br />profile sampling in areas expected to have a potential for source term material, and that <br />may have an immediate impact on alluvial groundwater and surface water in the creek. <br />3. During the late summer or fall season when water tables are at their lowest level, use a <br />backhoe to dig small trenches that provide access to the soil profile for in-situ gamma <br />measurements and soil sampling at incremental depths. Take photos and document <br />pertinent sampling information (e.g., date, sample ID, sample depth, GPS reading for <br />location, general descriptions and observations). <br />4. As samples are collected, analyze them in a small on-site soils laboratory for Ra-226 <br />content as described in the Radiation Monitoring License decommissioning plan. Compile <br />results and generate depth profiles of soil Ra-226 versus sample depth. A similar <br />procedure may be employed for uranium using XRF screening measurements. Use <br />analytical results to identify any layers of interest and, if possible, create three-dimensional <br />schematic maps of possible subsurface contamination. <br />5. Select representative sample aliquots to send to the laboratory for testing, including <br />uranium and Ra-226, along with EPA Method 1311 analysis by Toxicity Characteristic <br />Leaching Procedure. <br />6. Develop a report covering the "toxic forming" potential of alluvial fill source term <br />materials and include a related assessment of potential impacts (hydrologic and any others) <br />of disposal of this material in the mine workings from which they originated, via the <br />Minnesota portal. <br />7. If supported by the overall assessment, submit a Technical Revision request to dispose of <br />this material in the Minnesota portal, and include provisions for the excavation work, <br />re-grading and final re-vegetation.