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Historical Timeline for Dawn Mining Company


Dawn Mining Company (DMC) was licensed by the federal government to operate the uranium mill located near Ford, Washington, on 820 acres. The millsite is adjacent to the Spokane Indian Reservation; Chamokane Creek defines the northern and western boundary of the millsite and the eastern boundary of the reservation. DMC's Midnite Mine is located on the Spokane Indian Reservation, about 25 miles from the mill, and is under the jurisdiction of the federal government.


Washington State assumed full licensing and regulatory authority from the U.S. Nuclear Regulatory Commission (NRC).


Washington State Department of Health amended DMC's license, authorizing the disposal of uranium mill tailings into Tailings Disposal Area 4 (TDA-4).  TDA-4 is a below-grade impoundment, lined with high-density polyethylene (HDPE). TDA-4 was constructed to hold 44 million cubic feet of tailings, but only received 4 million cubic feet before shutdown.


After processing about 58 million cubic feet of ore, uranium milling ceased and the facility was placed in a care and maintenance mode.


DMC submitted a closure and reclamation plan for the millsite to the Department of Health.


After groundwater contamination from below TDAs 1, 2, and 3 was detected in wells and in seeps discharging to Chamokane Creek, the Department of Health issued a groundwater remediation order and established groundwater protection standards.


DMC submitted a revised closure and reclamation plan, which would provide for:

  • Demolition and disposal of the mill buildings.

  • Disposal of contaminated surface soils.

  • Cleanup of  groundwater contamination in the tailings area.

  • Filling of 44 million cubic foot Tailings Disposal Area 4 (TDA-4).

  • Covering, contouring and revegetating waste disposal areas.

  • Transfer of title to the site to the federal government for perpetual care and maintenance.

  • Closure activities to be completed by the year 2019.

Department of Health issued a Final Environmental Impact Statement (EIS), rejecting DMC's TDA-4 fill proposal of NORM (naturally occurring radioactive material).


DMC resubmitted their closure plan, with an alternate TDA-4 fill proposal for off-site uranium mill tailings.


Department of Health issued a supplement to the Final EIS, which found that DMC's alternative fill proposal was environmentally acceptable and posed no threat to human health and safety.

1995 Department of Health renewed DMC's radioactive materials license to allow them to implement its closure plan.  Receipt of out-of-state uranium mill tailings depended on the following license conditions being met:
  • Receive final Department of Health approval for all operations procedures.

  • Fully fund the trust fund for decommissioning, reclamation, and long-term surveillance and control of the millsite (approximately $14.4 million), or execute a surety bond in the amount of $14.4 million (the bonding company must be found financially secure by the State Finance Commission).

  • Finalize the site soil contamination survey and submit soil cleanup volume estimates to Department of Health.

  • Commence ground water remediation.

  • Commence construction of evaporation ponds.

  • Review of chemical characterization of potential tailings material by Department of Health, Department of Ecology, and the Local Citizens Monitoring Committee.


DMC completed construction of passive evaporation ponds that were designed to accept contaminated groundwater and process solution from TDA-4.  The five ponds were built over the unlined tailings disposal areas (TDAs 1, 2, and 3) and are lined with 60-mil HDPE, covering about 110 acres of the site.


The water was removed from TDA-4 and TDA-4 access was stabilized, and work begun to prepare TDA-4 for the receipt of fill material.  Pumping of groundwater into the evaporation ponds was resumed.


Department of Health renewed DMC’s radioactive materials license which continued to allow DMC to import out of state uranium mill tailings for TDA-4 fill material.  An extensive public process preceded license renewal.

2001 Department of Health amended DMC’s radioactive materials license to disallow disposal of off-site uranium mill tailing, to change the reclamation date from 2019 to 2013, to allow the direct disposal of sludge/filtercake from the Midnite Mine water treatment plant into TDA-4, and to require milestones for individual reclamation tasks.  The license amendment process included many public meetings. The Department of Health determined that the groundwater pump-back system in the unlined tailings disposal area was no longer effective in reducing contamination and directed DMC to prepare a Corrective Action Assessment with alternatives for remediation. DMC began groundwater testing to assess the effectiveness of creating a bio-remediation barrier to reduce uranium concentrations.
2003  DMC demolished the mill building and associated facilities, and disposed the debris into TDA-4.
2005  DMC completed major components of the millsite soil cleanup, including contaminated soils along State Highway 231 and the county entrance road. DMC excavated contaminated soils and disposed them into TDA-4.
2008 Following Department of Health approval, DMC ceased the bio-remediation corrective action for the tailings disposal area groundwater contamination. The field-scale assessment results showed that bio-remediation did not reduce contaminants to meet site groundwater protection standards. The Department of Health required DMC to continue monitoring groundwater quality and assessing the tailings disposal area contaminant plume. 
2009  DMC discovered groundwater contamination below the ore stockpile area, and initiated characterization studies of the ore stockpile area soil and groundwater.
2010 DMC completed installation of an HDPE liner over TDA-4 to cover the waste placed to date: tailings, mill debris, contaminated soils, water treatment plant sludge from Midnite Mine. 
2013  DMC constructed a new evaporation pond (EP6) with double-lined leak detection and 120-acre-feet capacity, divided into four 30-acre-feet cells. DMC transferred all remaining process water into EP6 and began installing the final cover over the unlined tailings disposal areas (TDAs 1, 2, and 3). 
2014  The Department of Health required that DMC develop a groundwater protection program to address groundwater quality downgradient of the ore stockpile area, that is out of compliance with state standards. The Department of Health amended DMC’s radioactive materials license considering current closure status including terminating Midnite Mine water treatment plant sludge disposal, updating environmental monitoring, incorporating a groundwater protection plan to address groundwater corrective actions for the tailings and ore stockpile areas, and completing the surface reclamation by the end of 2019. DMC continued installing the final cover over the unlined tailings disposal areas (TDAs 1, 2, and 3). 
2015  Most of the surface reclamation - building demolition, soils cleanup, tailings disposal area covering and reclamation, borrow area reclamation and flood diversion - is expected to be completed in 2015. After 2015, activities will include continued evaporation of process water in EP6, post-reclamation monitoring, environmental monitoring, and corrective actions for the two millsite groundwater contaminant plumes.