Riley Pass Uranium Mine Documents, Figures and Maps

Approximately 250 acres of disturbed highwall, pit floor, and spoils areas have been identified for reclamation and clean-up needs. Hazards within the Riley Pass area include high walls, pit floor, unstable overburden, elevated radioactive materials, and heavy metals.

Riley Pass old photoOnsite mine wastes are fine-grained particles readily dispersed by wind and surface water erosion.  Contaminants of concern include arsenic, molybdenum, thorium, and uranium.

Concentrations range from below established background to ten times higher for sediment samples in impacted drainages and several hundred times higher for mine waste samples.

In addition to materials on the website, newsletters are used to keep interested parties informed of reclamation work.  Newsletters have been previously distributed to interested parties and can be viewed or downloaded by clicking the following links:


2018 Summer Riley Pass Newsletter

2017 Fall Riley Pass Newsletter

2017 Spring Riley Pass Newsletter

2016 Spring Riley Pass Newsletter

2015 Spring Riley Pass Newsletter

2014 Spring Riley Pass Newsletter

2012 Summer Riley Pass Newsletter

2011 Winter Riley Pass Newsletter

2011 Spring Riley Pass Newsletter

2009-2010 Fall Riley Pass Newsletter



Riley Vicinity Map

Riley Bluff Identification Map

Numerous maps and figures are available in documents associated with the Riley Pass Site.  The links above provide basic site maps for reference.


Non-Tronox Action Memo - April 27, 2010

Riley Pass Action Memo - February 1, 2007


Technical Reports

Riley Pass Site Investigation and Data Collection Report (Feb 2017)

Bluff's F, G & I Verification Report (Feb 2017)

Final Waste Characterization Evaluation Report (Nov 2015)

Final Verification Sampling Plan (Nov 2015)

Riley Pass Sampling Memo 2015 (Aug 2015)

Tronox Bluff Waste Characterization Report (Jun 2013)

Survey of Topsoil Borrow Resources (Dec 2013)


Engineering Evaluation/Cost Analysis (EE/CA)

The Custer National Forest, Sioux Ranger District with the assistance of EPA and the State of South Dakota, has developed this final cleanup plan for the Riley Pass Abandoned Uranium Mine in the North Cave Hills. The Final EE/CA was released November, 2006.  Due to document size, the EE/CA is split into several sections to allow for downloading from this website.  Please click on the following links to download files for viewing:

Full document: Final Engineering Evaluation/Cost Analysis (2006)

Appendix A: Description of Federal and State ARAR's (Requirements)

Appendix B: Analytical Data for Riley Pass Site(1990)

Appendix C: Part I, Analytical Data for Riley Pass Site(1999 - 2000)

Appendix C: Part II, Analytical Data for Riley Pass Site - Surface Water Samples

Appendix D: Portage Environmental - Final Risk Assessment Report

Appendix E: Analytical Response Action/Cost Tables

Appendix F: Threatened and Endangered Species Coorespondence

Appendix G: Comment Responses

EE/CA Figures and Maps, Additional Documents

Figures and Maps- Part I

Figures and Maps- Part II


South Dakota School of Mines Final Impact Investigation 

This report addresses and evaluates the potential environmental impact of abandoned uranium mining and exploration sites in the North Cave Hills, Harding County, South Dakota. Specifically, this report addresses:

• Off-site migration of sediment spoils and associated metals and radionuclides from the

North Cave Hills region of USFS administered lands into potentially impacted drainages (sediments and surface waters);

• Sliding, slumping, and sheet erosion of mining spoils and associated metals and

radionuclides from USFS administered lands onto adjacent private lands;

• Off-site migration of airborne dust particulates and associated metals and radionuclides

by wind erosion of mining spoils from USFS administered lands onto adjacent and regional private lands;

• Potential contamination to the regional ground water supply by introduction of metals

and radionuclides into regional aquifers that provide drinking water to local residents and livestock.


Due to document size, the Impact Investigation Report is split into several sections to allow for downloading from this website.  Please view or download documents by clicking the following links:

Final Report Impact Investigation Part I

Final Report Impact Investigtation Part II

Final Report Impact Investigation Part III - Figures

Final Report Impact Investigation Part IV - Figures