2.1.1 Narrative 2.1.1.1 Current Situation
During this period the ERRS contractor completed excavation in the Arroyo area. The Arroyo area starts at the foot of the Mesa, just below the TSDA. Mine waste from the upper slope below the mine opening fell onto the TSDA and water erosion carried mine waste out into the Arroyo area. The largest volume of contaminated soils at the Site, approximately 14,000 cubic yards, were located in the Arroyo area.
The skyline cable yarding system in use at the Site consists of a mainline cable strung between a bottom anchor and a top tower. A carriage runs along the cable and its movement is controlled by a haulback cable. The top tower controls tension of the mainline, and thus its height, as well as the movement of the carriage with the haulback cable. Accessories such as a bucket are attached to the carriage. This system is being used at the Site to move stockpiled mine waste from the valley floor to the top of the Mesa. The waste is then loaded into a haul truck and transported a short distance to the on-site repository. The yarder is also being used with a dredge bucket attached to the carriage to excavate steep sections of the slope below the mine opening on the edge of the Mesa that were inaccessible with an excavator.
June 20 – 25, 2011 OSC Stilman (R4) onsite this week. This week ERRS: -Continued water conveyance system operations. -Continued site-wide road improvements and maintenance. -Continued dust control program using water for dust suppression. -Continued excavation of contaminated soils in the Arroyo area. Excavated soils were stockpiled and coated with soil sealant to prevent migration, pending transport via skyline yarder to repository on top of the Mesa. -Continued transport of stockpiled mine waste materials to top of Mesa via the skyline cable yarder. -Began preparing the dredge bucket for excavation on lower portion of upper slope area below mine. START delineated excavation extent in the TSDA area, performed air sampling around work zones as part of the effluent dust sampling program, and performed radiation surveys as needed. June 27 – 30, 2011 OSC Musante onsite this week. This week ERRS: -Completed excavation of contaminated soils in the Arroyo area. -Continued water conveyance system operations. -Continued site-wide road improvements and maintenance. -Continued dust control program using water for dust suppression. -Continued transport of stockpiled mine waste materials to top of Mesa via the skyline cable yarder. -Began excavation on lower portion of upper slope area below the mine opening using the skyline with a dredge bucket. START delineated excavation extent in the TSDA area, performed air sampling around work zones as part of the effluent dust sampling program, and performed radiation surveys as needed. July 1 – 5, 2011 Site operations suspended to give personnel a break for the July 4th Holiday. The skyline yarder subcontractor will remain onsite to inspect and repair the system (see section 2.5 Safety Officer for information related to malfunction incident).
2.1.2 Response Actions to Date
Mobilization for removal activities and site setup began the week of March 28, 2011. Construction of the repository began the week of April 4, 2011, and was completed at the end of May. Excavation of mine waste from the upper slope below the mine opening and valley floor areas on the north side of Oljato Mesa began in early June and continues.
2.1.3 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs) EPA to date has been unable to identify any existing PRPs. EPA will continue to analyze the voluminous responses to the information requests it sent to numerous parties associated with mining in general on the Navajo Reservation. Because of the urgency of this removal, EPA is proceeding with a fund-lead action. EPA will continue to review the information referenced above to determine whether viable and liable parties may be identified, and will pursue recovery of the removal costs if appropriate. 2.1.4 Progress Metrics
There are no progress metrics to report at this time. Off-site disposal is not planned for this removal. Uranium mine wastes at the Site will be transferred to the on-site repository. Total volumes of waste moved into the repository may be reported in future POLREPs.
Waste Stream | Medium | Quantity | Manifest # | Treatment | Disposal | | | | | | | | | | | | | | | | | | |
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