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Decommissioning Plan Schwartzwalder Mine <br /> <br /> <br />RML CO-369-06 <br />Cotter Corporation (N.S.L.) 9 March 2017 <br />2.9 pCi/g uranium and 1 pCi/g Ra-226). These values are consistent with national averages and <br />are conservative with respect to development of dose-based soil cleanup criteria for RML #2. <br /> <br />2.4 Gamma Walkover Survey <br />A GPS-based gamma radiation survey was performed at the Schwartzwalder mine site during <br />July, 2007 (Tetra Tech, 2007). The mapping was performed to assess remedial actions that have <br />already been performed, and to identify areas at the site that may require further remedial action. <br />The results were plotted on a site contour map to present elevation and scale. <br /> <br />Gamma Survey Procedure <br /> <br />Gamma detector instrumentation used for the survey included 2×2” Ludlum Model 44-10 <br />sodium iodide (NaI) detectors, connected to Ludlum Model 2350 rate meters. Each Ludlum rate <br />meter, and a Garmin Global Positioning System (GPS) unit, was connected to a laptop computer <br />or a personal digital assistant to record gamma exposure rate and GPS data. Each survey system <br />was carried in a backpack, providing a gamma detector height of approximately 3 feet. <br /> <br />Walking speed for the mapping survey was approximately two miles per hour. Wherever <br />possible, adjacent scan travel paths were kept within 8 feet of each other to maintain complete <br />scan coverage. Data was periodically downloaded in the field to assess coverage and to indicate <br />the need for supplemental scanning. <br /> <br />The areas scanned included the main valley floor, and the stream portion up-valley from the <br />operations area. Much of the site contains medium to large rocks, restricting access in some <br />locations. Scanning was performed as close to the stream as possible in the operations area. <br />Each of the waste rock piles was partially scanned. A scan was also conducted along the steep <br />dirt road that leads generally south, up and out of the valley. This road passes two mine adits, <br />and ascends the slope to a mine exhaust vent and the property boundary. A detector system was <br />also used to scan the center line of the access road leading from the site to Ralston Reservoir. <br />The results of the gamma survey were kriged in GIS to provide continuous color-coded contours <br />of gamma levels. Results of the survey are provided in Figure 7. <br /> <br />2.5 Scoping Survey <br />2.5.1 Structures <br />A contamination survey of the OWTP structures, systems and components was conducted in <br />2008 to determine radiological conditions for demolition planning. Survey locations were <br />selected on surfaces with a higher potential for contamination such as floor and walls, work <br />surfaces, and sumps and drains. <br /> <br />Direct alpha and beta/gamma levels were recorded for 44 selected survey locations along with <br />smear survey results to document both direct and removable contamination levels. Frequency <br />histograms of the resulting data are shown in Figure 8. These results indicated that only 2 of the <br />44 locations surveyed were slightly in excess of fixed plus removable criteria for free release and <br />unrestricted use (see Section 3.1). The building has since been used to house and operate an IX <br />treatment system. After the IX equipment is relocated to the NWTP, radiological contamination