{{Use American English|date=June 2025}} {{use mdy dates|date=September 2013}} {{Infobox superfund | name = Midnite Mine | image = | caption = | city = Wellpinit | county = Stevens County | state = Washington | location_map = USA Washington | coordinates = {{coord|47|56|30|N|118|05|35|W|format=dms|display=inline,title|type:landmark_region:US-WA}} | CERCLIS_ID = WAD980978753 | contaminants = Metals and radionuclides | responsible = | proposed = 02/16/1999 | listed = 05/11/2000 | construction = 2024 (planned)}} <!-- Note: As of September 2013 (the time it was copy edited), this article used serial (Harvard) commas. --> [[File:USGS Midnite Mine geological cross sections.png|thumb|400px|Midnite Mine geological cross sections, where Kp is the pluton.]] The '''Midnite Mine''' is an inactive uranium mine in the Selkirk Mountains of the state of Washington that operated from 1955 to 1965 and again from 1968 to 1981. Located within the reservation of the Spokane Tribe of Indians, it is approximately {{convert|8|mi}} from Wellpinit, Stevens County. The mine was listed as a Superfund site under the ''Comprehensive Environmental Response, Compensation, and Liability Act'' of 1980 (CERCLA) on May 11, 2000. In addition to elevated levels of radioactivity, heavy metals mobilized in uranium acid mine drainage pose a potential threat to human health and the environment.<ref name=sitenarrative>{{cite web|title=Midnite Mine site narrative |url=http://www.epa.gov/superfund/sites/npl/nar1546.htm |accessdate=2009-12-21 |archiveurl=https://web.archive.org/web/20130921061129/http://www.epa.gov/superfund/sites/npl/nar1546.htm |archivedate=September 21, 2013 |url-status=dead }}</ref><ref name=seattletimes>{{cite web|url=http://seattletimes.nwsource.com/html/pacificnw/2004191779_pacificpuranium24.html |title=Radioactive Remains: The forgotten story of the Northwest's only uranium mines |date=2007-11-24 |author=Cornwall, Warren |accessdate=February 24, 2008 |publisher=Seattle Times |archiveurl=https://web.archive.org/web/20130921103052/http://seattletimes.com/html/pacificnw/2004191779_pacificpuranium24.html |archivedate=September 21, 2013 |url-status=dead }}</ref><ref name=epa2016>{{cite web|title=EPA Superfund Program: Midnite Mine, Wellpinit, WA|url=https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=1001070|website=United States Environmental Protection Agency|accessdate=30 September 2016|location=Washington, DC|date=17 September 2016}}</ref><ref name=agreement/>
==Geology== Uranium at the Midnite Mine occurs in discordant deposits in crystalline host rocks. Ore bodies are in metamorphosed steeply dipping Precambrian pelitic and calcareous rocks of a roof pendant adjacent to a Cretaceous porphyritic quartz monzonite pluton.<ref>{{cite web|last1=Nash|first1=J. Thomas|last2=Ludwig|first2=Ken R.|title=Limitations on Genesis of Uranium Ores, Midnite Mine, Washington, Based on Lead-Uranium Ages|url=https://pubs.usgs.gov/of/1979/1178/report.pdf|website=USGS Publications Warehouse|publisher=U.S. Geological Survey|accessdate=6 April 2017|location=Reston, VA|page=1|date=1979}}</ref><ref name="geol">{{cite web|last1=Nash|first1=J. Thomas|last2=Lehrman|first2=Norman J.|title=Geology of the Midnite uranium mine, Stevens County, Washington; a preliminary report|url=https://pubs.usgs.gov/of/1975/0402/report.pdf|website=USGS Publications Warehouse|publisher=U.S. Geological Survey|accessdate=30 September 2016|location=Reston, VA|date=1975}}</ref>
The uranium deposits are generally tabular with dimensions ranging up to {{convert|1250|ft}} long, {{convert|690|ft}} wide and {{convert|165|ft}} thick. Deposits are bounded on at least one side by unmineralized granitic rock. The thickest mineralized zones invariably occur at depressions or flexures in the granitic contact.<ref name="geol"/>
Shallow ore is mainly autunite. Deeper ore is pitchblende and coffinite with abundant pyrite and marcasite. Uranium minerals occur disseminated along foliation, as replacements and stockwork fracture-fillings. There is no stratigraphic control of ore deposition. Most ores are muscovite schist and mica phyllite, with some deposits in calc-silicate hornfels. Uranium minerals were deposited over time from late Cretaceous to late Tertiary.<ref name="geol"/>
==Discovery and mining== In 1954 brothers Jim and John LeBret, members of the Spokane Tribe, found uranium on the tribal reservation in Washington state. The brothers and several other tribal members formed Midnite Mines, Inc. and secured mining leases administered by the United States Bureau of Indian Affairs. Midnite Mines then joined with Newmont USA Limited, a U.S. mining conglomerate, to form the mine operator Dawn Mining Company (DMC), with Newmont as 51% shareholder and Midnite Mines owning 49%.<ref name=agreement>{{cite web|title=Case Summary: Cleanup Agreement Reached at Former Uranium Mine on Spokane Indian Reservation|url=https://www.epa.gov/enforcement/case-summary-cleanup-agreement-reached-former-uranium-mine-spokane-indian-reservation|website=US Environmental Protection Agency|accessdate=30 September 2016|location=Washington, D.C.|date=14 June 2016}}</ref>
Uranium ore was transported from the Midnite Mine to DMC's mill {{convert|25|mi}} east of the mine near Ford, Washington, outside the reservation boundary. Mining produced approximately 2.9 million tons of ore averaging 0.23 percent uranium oxide. 2.4 million tons of stockpiled low-grade ore, containing about 2 million pounds of uranium oxide, and 33 million tons of waste rock were retained on site.<ref>{{cite web|title=Midnite Mine Superfund Site, Spokane Indian Reservation, Washington, Record of Decision |url=http://www.epa.gov/region10/pdf/sites/midnite_mine/midnite-mine-rod-06.pdf|archive-url=https://web.archive.org/web/20121021122344/http://www.epa.gov/region10/pdf/sites/midnite_mine/midnite-mine-rod-06.pdf|url-status=dead|archive-date=October 21, 2012|date=September 2006|accessdate=2012-09-13}}</ref>
==Environmental reclamation== Two exposed pits, back-filled pits, waste rock piles, and low-grade ore stockpiles remain on site.<ref name=epa1/> Contaminated water surfacing below waste rock and ore stockpiles is collected and treated on-site at a water treatment plant, then discharged into Blue Creek, which enters the Spokane Arm of Franklin D. Roosevelt Lake.<ref name=epa2016/><ref>{{cite web|title=Biological Assessment Midnite Mine – Revision 2|url=https://www3.epa.gov/region10/pdf/sites/midnite_mine/midnite_mine_biological_assessment_september2014.pdf|archive-url=https://web.archive.org/web/20151014043647/http://www3.epa.gov/region10/pdf/sites/midnite_mine/midnite_mine_biological_assessment_september2014.pdf|url-status=dead|archive-date=October 14, 2015|website=U.S. Environmental Protection Agency|publisher=Worthington Miller Environmental, LLC|accessdate=30 September 2016|date=September 2014}}</ref>
In 2001, the State of Washington decided that a ground water pump-back system was no longer effective in reducing contamination. It directed DMC to prepare a Corrective Action Assessment of remediation alternatives. The final cleanup plan for the site, projected to cost approximately $193 million, was issued in a Record of Decision on 29 September 2006, which called for a cap over the area of pits back-filled with waste during mining, consolidation and containment of the remaining waste within the two remnant open pits, removal of water entering the pits, and operation of a treatment system to treat contaminated water from the pits and seeps.<ref name=epa2016/><ref name=epa1>{{cite web |url = http://yosemite.epa.gov/r10/cleanup.nsf/9f3c21896330b4898825687b007a0f33/25f296f579940d8b88256744000327a5!OpenDocument |title = Region 10 Cleanup: Midnite Mine |date = 2007-11-21 |accessdate = February 24, 2008 |publisher = United States Environmental Protection Agency |archiveurl = https://web.archive.org/web/20120207025319/http://yosemite.epa.gov/r10/cleanup.nsf/9f3c21896330b4898825687b007a0f33/25f296f579940d8b88256744000327a5!OpenDocument |archivedate = February 7, 2012 |url-status = dead }}</ref> In 2007, ground water tests had commenced.<ref name=wadoh>{{cite web|url=http://www.doh.wa.gov/ehp/rp/waste/dmchm.htm |title=Dawn Mining Company |date=2007-04-06 |accessdate=February 24, 2008 |publisher=Washington State Department of Health |url-status=dead |archiveurl=https://web.archive.org/web/20070630215451/http://www.doh.wa.gov/ehp/rp/waste/dmchm.htm |archivedate=June 30, 2007 }}</ref>
The EPA finalised a Consent Decree in January 2012, with DMC and Newmont to complete the cleanup work, and the federal government contributing a share of the cleanup costs. The EPA will oversee the cleanup work in coordination with the Spokane Tribe. Dawn and Newmont completed the engineering design of the cleanup works in October 2015.<ref name=epa2016/>
In May 2016 site preparation works for the environmental cleanup began, including installation of contractor facilities, access road construction and stockpile relocation. The major components of the cleanup are planned for the period from 2017 to 2024.<ref name=epa2016/>
==See also==
* List of Superfund sites in Washington (state)
==References== {{Reflist}}
Category:Buildings and structures in Stevens County, Washington Category:Uranium mines in the United States Category:Surface mines in the United States Category:Mines in Washington (state) Category:Superfund sites in Washington (state) Category:1955 establishments in Washington (state) Category:1981 disestablishments in Washington (state) Category:Spokane Tribe