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Mine Design, Operations & Closure Conference -2004

Mine Design, Operations & Closure Conference -2004. Characterizing Ground-Water Flow Paths in High -Altitude Fractured - Rock Settings Impacted by Mining Activities Mike Wireman, U.S. EPA Region 8 Dr. Mark Williams, University of Colorado. Mary Murphy Gold Mine Applied Research Site

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Mine Design, Operations & Closure Conference -2004

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  1. Mine Design, Operations & Closure Conference -2004 Characterizing Ground-Water Flow Paths in High -Altitude Fractured - Rock Settings Impacted by Mining Activities Mike Wireman, U.S. EPA Region 8 Dr. Mark Williams, University of Colorado

  2. Mary Murphy Gold Mine Applied Research Site Research Objectives: * To Develop Tools for Characterization of Site Hydrology and Geochemistry * To Better Understand Role of Ground Water Transport of Metals to Chalk Creek. Remedial Objectives: * To Determine Metals Loading Sources and Pathways * To Reduce Metal Loadings to Chalk Creek Partners: * USGS, USFS, University of Colorado & CDMG

  3. Mary Murphy Gold Mine—Applied Research Site • Mining History • Placer Mined in 1860’s-1870: Vein Deposits Located • 1883-1893: Period of Greatest Mining Activity • Mary Murphy Mine: 1870—1951 • * 75% Gold, Silver, Lead, Zinc, Copper • * 5 Main Veins • * 14 Main Levels • * 2200 Vertical Feet • * Golf Adit—Drain / Haul Adit • * Connected to Iron Chest Mine • Remedial Work: • * 1991—3 Piles Consolidated 69,000 cu. yds., • Golf Tunnel Unplugged, Lined Settling Pond • * 1992—Golf Adit Water Rerouted • * 1998—1400 Level Opened / Stabilized • * 1999—700 Level Partially Opened • * 2003—Lady Murphy Adit Opened

  4. Mary Murphy Mine Site Environmental Characterization History > Flow Measurements > Steam Tracing 14 Times –1990—2003 > GW Tracing > Metal Loading > Geochemical 5 Times- 1990—1994 Modeling > Sediment Sampling > Hydrometrics / Sept. ’93 & June ’99 Isotopic Research > Water Chemistry > Surficial 17 Times- 1990—2003 Geophysical Work > Toxicity Testing / Fish Data 11 Times- 1991—2003

  5. Focus Of This Talk > Metals Loading > Stream & Ground-Water Tracing > Hydrometrics / Isotopic Results

  6. Chalk Creek Mining District-Collegiate Range, CO

  7. Geology and Mine Features Mary Murphy Mine & Vicinity

  8. Elements of Conceptual Model • Strong GW / SW Interaction • > Gaining Streams • > Strong Upward Gradient in Valley Bottom • Fracture Dominated Flow Paths • Multiple GW Flow Systems • Many Seeps / Springs • Significant Seasonal Variation in Flow and Water Quality • ( GW & SW) • Several Water Types • Chemistry of GW & SW is Strongly Impacted by Geology and • Mineralogy of Ore Body, and Mine Features.

  9. Mary Murphy Gold Mine—Chafee County, CO DISSOLVED ZINC CONCENTRATIONS Location Date Conc. (ug/l) Chalk Creek CC-9 9/90 < 100 CC-9 7/00 118 CC-9 7/02 24 CC-9 5/03 Upstream of Pomeroy 35.2 CC-7D 9/90 110 CC-7D 7/02 44 CC-7D 5/03 Upstream of Golf 53.2 CC-7 9/90 18,000 CC-7 7/00 27,710 CC-7 7/02 24,300 CC-7 Golf Adit 3,620 CC-6 9/90 420 CC-6 2/02 417 CC-6 5/03 Upstream of Iron Chest 534 CC-0 9/90 < 100 CC-0 7/02 At Arkansas 08

  10. Mary Murphy Gold Mine—Chafee County, CO DISSOLVED ZINC CONCENTRATIONS Location Date Conc. (ug/l) GW Wells MM-15 9/93 45 MM-15 Bedrock 7/02 08 MM-11 9/93 188 MM-11 7/00 210 MM-11 7/02 179 MM-11 Allurial 5/03 560 MM-3 9/93 17,131 MM-3 7/00 15,830 MM-3 2/02 21,500 MM-3 Bedrock 5/03 5,570 MM-6 9/93 2605 MM-6 7/02 13,700 MM-6 Allurial 122,000

  11. Scope of Ground-Water Tracing Mary Murphy Mine—Applied Research Site

  12. Results of Ground Water Tracing Mary Murphy Mine

  13. Inverse Geochemical Modeling

  14. Variation of Discharge Components Versus Time in 1400 Level. Mary Murphy Gold Mine

  15. Delta O-18 in Selected Tributary Inflows, 1400 Level Mary Murphy Gold Mine

  16. Pre-event Water and Event Water in Total Discharge From 1400 Portal Mary Murphy Gold Mine

  17. HELIUM DATAMary Murphy Mine site • ESTIMATED AGES OF GROUND WATER • Using tritium data from different date • t = 12.43/ln2 . ln ( 1 + [3Het] / [3Ht] ) Clark & Fritz p188 • BEDROCK WELLS • MM 3 - 2-4 YRS • MM 18 - 2-3 YRS • MM 15 - ABOUT 8 YEARS OLD • ALLUVIAL WELLS • MM11 - 3-4 YRS • Source – A. Manning -USGS

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