2017-06-05_REVISION - M1977300 - Laserfiche WebLink

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Technical Revision 25, Rev. 1 Schwartzwalder Mine 2.0 TR-23 AMENDMENT 2.1 DESCRIPTION OF ACTIVITY The CDPHE is currently reviewing an amendment to Cotter's RML 369-06 to decommission - RML#2. Most of the activities addressed by this amendment are addressed by TR-23. Decommissioning activities under RML 369-06 will include the following: • Move the ion exchange (IX) columns from the current Old Water Treatment Plant (OWTP) to the NWTP. • Perform radiation surveys to detect radioactive contamination in the OWTP. • Decontaminate and demolish the OWTP. Any equipment that can be reused or salvaged will be saved. All other demolition materials will be placed into the Minnesota Adit. • Demolish the concrete containment and place the materials into the Minnesota Adit. • Excavate alluvial materials below the OWTP, concrete containment, and throughout RML#2: o Materials that meet the approved gamma screening criterion (22 µR/hr) will be placed on the waste rock piles o Materials that exceed the screening criterion will be placed in the Minnesota Adit. These activities are discussed in Cotter's RML decommissioning plan (Cotter, 2017). The following sections describe various aspects of Cotter's decommissioning plan. 2.2 PREVIOUS RADIOLOGICAL CONTAMINATION ASSESSMENTS Information in the following subsections was obtained from Cotter's RML Decommissioning Plan (Cotter 2017). 2.2.1 Gamma Walkover Survev A GPS-based gamma radiation survey was performed at the Schwartzwalder mine site during July, 2007. These surveys were performed to assess remedial actions that have already been performed, and to identify areas at the site that may require further remedial action. Results of the survey are provided in Figure 2-1. Gamma detector instrumentation used for the survey included 2-inx2-in Ludlum Model 44-10 sodium iodide (NaI) detectors, connected to Ludlum Model 2350 rate meters. Each Ludlum rate meter, and a Garmin Global Positioning System(GPS) unit, were connected to a laptop computer or a personal digital assistant to record gamma exposure rate and GPS data. Each survey system was carried in a backpack, providing a gamma detector height of approximately 3 feet. Walking speed for the mapping survey was approximately two miles per hour. Wherever possible, adjacent scan travel paths were kept within 8 feet of each other to maintain complete scan coverage. Data was periodically downloaded in the field to assess coverage and to indicate the need for supplemental scanning. Mine Permit M-1977-300 Cotter Corporation(N.S.L.) 4 June 2017