Dawn Mining Company (State of Washington)

This site description was provided by the cognizant Agreement State, and the U.S. Nuclear Regulatory Commission (NRC) makes no claim regarding the validity of the information provided. See our Site Disclaimer for more information.

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 submitter their first closure plan. After a lengthy public process, the final closure plan was approved in February 1995. The lengthy schedule is determined by the amount of time it takes to evaporate 540 acre feet (140,000,000 million gallons) of process water left from mill operations. Once the evaporation process is complete, the Final Cover can be constructed over approximately 120 acres of old tailings areas. The DMC mill was buried in a below grade lined impoundment in 2003. Approximately 750,000 cubic yards of contaminated soils have been cleaned up in 2005, 2009 and 2010. It is estimated that only about 20,000 cubic yards of material remain to be cleaned up  consisting of office buildings, a shower house and a couple of sheds made of corrugated steel dating back to the 1950s. Soils are being cleaned up to meet the radium standards specified in Chapter 246-252 Washington Administrative Code, which is consistent with 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. Once cleanup and reclamation are complete and the stability of the site has been proven, it is the intent of Washington State to terminate DMCs 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

In 2010 a previously unknown ground water contaminant plume was discovered in the area of the former ore stockpile area. Studies are underway to characterize the extent and significance of the ore stockpile ground water plume. Final reclamation cannot occur until it is determined whether the plume will need to be pumped and treated in existing evaporation ponds. Previously, a separate ground water contaminant plume down-gradient from old tailings areas, of limited aerial extent, has been monitored and has cleaned up naturally over time. A pumping program for this plume captured the worst part of the plume and pumping was suspended in the mid-1990s. The State PM for the site is Dorothy Stoffel.

4.0 Estimated Date For Closure