Montana Department of Environmental Quality Mine Waste Cleanup Bureau

1. Garnet Mine Area Reclamation ProjectFinal Engineering Evaluation/Cost AnalysisPublic Meeting – March 3, 2010 Montana Department of Environmental Quality Mine Waste Cleanup Bureau

2. Project Location • Located approximately 2.5 miles southwest of Pony, Montana in the Mineral Hill (Pony) Mining District of Madison County. Pony Garnet Mine

3. Mining History • Mining • Garnet Mine began underground operations mining gold, silver, copper and lead in the late 1800s. • Most production occurred between 1897 and 1909 and continued intermittently through the 1930s. • Milling • Initial milling was conducted using a 20-stamp amalgamation mill. • Later used conventional floatation mill and tailings facility to produce concentrate for shipping. • Production Estimate – • 175,000 tons of ore

4. Garnet Area Mine Features • Adits, some caved • Waste Rock Piles • Shafts and Collapsed Stopes • Valley Fill Tailings • Other Hazardous and Non-Hazardous Materials from Past Mining and Milling

5. Oriole Adit Portal (F-7) with Seepage Flow 2.2 – 7.1 gpm

6. Oriole Adit Waste Rock Dump (F-8)

7. Collapsed Stope (F-2)

8. Cross Valley Tailings Deposits in Cataract Creek

9. Mine Features

10. Purpose and Objectives Purpose – Prepare a functional guide for conducting reclamation activities that to the extent possible mitigate human health and environmental risks. Objectives – To screen, develop and evaluate potential response alternatives that would be used to clean up site mine waste.

11. Waste Rock Characteristics

12. Waste Rock Characteristics Mine Waste Rock Investigation • Acid-Base Accounting (ABA) – determine potential to generate acidic leachate • Metal Mobility – evaluate potential to release metals in concentrations exceeding DEQ surface water standards • Volume Survey – determine total volume of each waste pile

13. Sampling Waste Rock Dump (F-3)

14. Waste Rock Characteristics - Acid-Base Accounting

15. Waste Rock Characteristics - Acid-Base Accounting ABA Results Summary • Uncertain acid generation potential indicated by NNP (values between +20 and -20 CaCo3/kiloton of rock) • 3 Samples have somewhat greater potential to generate acid based on NP:AP (values below 1)

16. Waste Rock Characteristics – Metal Mobility

17. Waste Rock Characteristics – Metal Mobility Summary Metal Mobility Summary • All six waste rock samples exceeded DEQ-7 acute aquatic life, chronic aquatic life, and/or human health standards for surface water for at least one metal. • Pb was most common metal detected constituent • Cu exceeded acute aquatic life standards in five of six samples • Standards for As, Cd, Hg, or Zn were exceeded in three or fewer samples

18. Waste Rock Characteristics – Preliminary Volumes

19. Tailings Characteristics

20. Tailings Characteristics Floodplain Tailings Investigation • Test pits were excavated throughout the tailings deposit • Excavated test pits were sampled at 1ft. Intervals below ground surface • Samples were analyzed using and X-ray Fluorescence (XRF) instrument and compared to background soil samples

21. Cross Valley Tailing Deposits (Cataract Creek)

22. Eroded Tailings Dam – Cascade Creek Assumed Original Top of Dam Estimated Height 8’-10’

23. Primary Tailings Deposit Test Pit

24. Primary Tailings Deposit Test Pit

25. Typical Wetland Marsh/Floodplain Area

26. Typical Marsh Area Tailings

27. Tailings Map with Sampling Locations

28. Oriole Adit

29. Oriole Adit Portal (F-7) with Seepage Flow 2.2 – 7.1 gpm

30. Oriole Adit (1,070 feet)

31. Oriole Adit – Drift in Mineralized Structure

32. Oriole Adit – Mineralized Stopes

33. Oriole Adit Workings (1,095 feet) Malachite (Cu) precipitate from Jackleg Drill Holes

34. Oriole Adit Plan Map Oriole Adit Seepage Flow 2.2 – 7.1 gpm

35. Exceedances of Surface Water Quality Standards

36. Ecological Risk Assessment

37. Human Health Recreational Use Risk Assessment No Human Health affects from tailings, waste rock or surface water (excluding the Oriole Adit seepage) for any of the following recreational uses • Soil Ingestion • Dust inhalation • Water Ingestion • Fish Ingestion

38. Development and Screening or Reclamation Alternatives Purpose – Identify and screen technology types and process options • Eliminate technologies that are obviously unfeasible or ineffective • Retain potentially effective options General Response Actions • No Action – no further response or monitoring • Institutional Controls – restrict or control access • Engineering Controls –reduce or eliminate the contaminant • Excavation and Treatment – removal and subsequent treatment of contaminant • In-Situ Treatment – treat in place, reducing mobility and toxicity of contaminant

39. No Action • No Action is generally used as a baseline against which other response options are compared

40. Institutional Controls • Land use restrictions would limit the possible future uses of the land at the site • Mine portal closures • Fencing and gates • Area closures • Institutional Controls do not meet clean-up goal • Does not address long term public safety

41. Engineering Controls Engineering Controls typically include containment, capping, run-on/run-off controls, revegetation and/or disposal • Underground Flow Control – eliminate, minimize, or divert contaminated water flows for entering or leaving underground mine workings • Containment – eliminate direct contact and fugitive releases of contaminated materials • Surface Controls – minimize contaminate release and migration • On-Site Disposal – placement of contaminate in an engineered on-site repository • Off-Site Disposal – transporting contaminate to an engineered off-site repository permitted to accept such materials

42. Excavation and Treatment Excavation and Treatment involves the removal of the contaminated materials and subsequent treatment to reduce toxicity and/or volume • Reprocessing– transporting contaminate to existing mill or smelter for processing and recovery of valuable metals • Fixation/Stabilization – chemically alter the contaminant to reduce its mobility or toxicity or encapsulating contaminant in inert material • Physical/Chemical Treatment – use of physical chemical processes to concentrate constituents into a smaller volume for disposal or further treatment

43. In-Situ Treatment In-Situ Treatment involves treating contaminate in place with the objective of reducing mobility and toxicity of problem constituents. • Physical/Chemical Treatment – used to create a chemical or physical change in the mobility and/or toxicity of the contaminants • Thermal Treatment – used to melt contaminated solid media in place to immobilize metals into a glass-like, inert, non-leachable solid matrix

44. Response Alternative Development

45. Mine Feature Response Alternative Development

46. Example of Response Alternative Development

47. Detailed Analysis of Alternatives Response Action Alternative Evaluation 1. Effectiveness 2. Implementability 3. Cost

48. Detailed Analysis of Alternatives Effectiveness – • Overall protection of human health and the environment • Compliance with the ARARs • Long-tem effectiveness and performance • Reduction of toxicity, mobility, or volume through treatment • Short-term effectiveness

49. Detailed Analysis of Alternatives Implementability – • Address the technical and administrative feasibility of implementing an alternative and the availability of various services and materials required to accomplish its implementation.

50. Detailed Analysis of Alternatives Cost – • Developing conservative cost estimates based on the materials needed and the construction elements associated with implementing the alternative. • Cost do not necessarily represent the cost the may actually be incurred because many design details are preliminary at this stage.