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Dawn Mining Company (WA State)

1.0 Site Identification

2.0 Site Status Summary

The Dawn Mining Company uranium millsite has always been owned by DMC. The mill began operations in 1957 and shut down in 1982. After the mill shut down it was on standby status until 1989 when DMC submitted their first closure plan. After a lengthy public process, the final closure plan was approved in February 1995. The lengthy closure and reclamation schedule is determined by the amount of time it takes to evaporate 540 acre feet (140,000,000 gallons) of process water are only approximately 50 acre feet of process water remaining to evaporate. Once the evaporation process is completed, then the Final Cover can be constructed over approximately 120 acres of old tailings areas. The Dawn Mining Company mill was buried in a below grade, lined tailings impoundment (Tailings Disposal Area 4 or TDA4) in 2003. Over 500,000 cubic yards of contaminated soils have been cleaned up, largely during 2005. It is projected that only about 28,000 cubic yards of contaminated soils and site structures remain to be disposed into TDA4. The site structures consist of office building, shower house and a couple of sheds made of corrugated steel dating back to the 1950s. The soils are being cleaned up to meet the radium standards specified in Chapter 246-252, Washington Administrative Code, which is consistent with 10 CFR Part 40, Appendix A criteria for soil cleanup at sites with closure plans approved prior to June 11, 1999. However, based upon the principal of ALARA, DMC has committed to cleaning up uranium to an acceptable dose. Most of the remaining uranium in soil is located in the former ore stockpile area and will be cleaned up with the radium in the shallow soil profile. Once cleanup and reclamation are complete and the stability of the site has been proven, it is the intent of Washington State to terminate DMC's license and the site to be turned over to US Department of Energy for long term care and maintenance.

3.0 Major Technical or Regulatory Issues

All of the major technical issues with surface cleanup and reclamation have been resolved. There is a ground-water contaminant plume of limited aerial extent associated with sands and gravels of an alluvial bench underlying the site. The ground water plume has significantly cleaned up naturally over time. A pumping program completed in the early 1990s also captured the worst part of the contaminant plume. That pumping program was suspended in the mid-1990s when it was no longer effective at improving ground water quality. A ground water bioremediation pilot program was conducted from 2004 to 2006, but proven to not sustain improved ground water quality. DMC has indicated that they will be applying for ground water alternate concentration limits in the near future. Washington State will follow NRC guidance in the review and approval process of an ACL application. The State PM for the site is Dorothy Stoffel.

4.0 Estimated Date For Closure

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Friday, September 26, 2008