mine design, operations & closure conference -2004

28
aracterizing Ground-Water Flow Paths in High - titude Fractured - Rock Settings Impacted by ning Activities ke Wireman, U.S. EPA Region 8 . Mark Williams, University of Colorado

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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 - PowerPoint PPT Presentation

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Page 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

Page 2: Mine Design, Operations & Closure Conference -2004

Mary Murphy Gold MineMary Murphy Gold MineApplied Research SiteApplied 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

Page 3: Mine Design, Operations & Closure Conference -2004

Mary Murphy Gold Mine—Applied Research SiteMining 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

Page 4: Mine Design, Operations & Closure Conference -2004

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

Page 5: Mine Design, Operations & Closure Conference -2004

Focus Of This Talk

> Metals Loading > Stream & Ground-Water Tracing

> Hydrometrics / Isotopic Results

Page 6: Mine Design, Operations & Closure Conference -2004

Chalk Creek Mining District-Collegiate Range, CO

Page 7: Mine Design, Operations & Closure Conference -2004

Geology and Mine FeaturesMary Murphy Mine &

Vicinity

Page 8: Mine Design, Operations & Closure Conference -2004

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.

Page 9: Mine Design, Operations & Closure Conference -2004

Mary Murphy Gold Mine—Chafee County, CO DISSOLVED ZINC CONCENTRATIONS Location Date Conc. (ug/l)Chalk CreekCC-9 9/90 < 100CC-9 7/00 118CC-9 7/02 24CC-9 5/03 Upstream of Pomeroy 35.2

CC-7D 9/90 110CC-7D 7/02 44CC-7D 5/03 Upstream of Golf 53.2

CC-7 9/90 18,000CC-7 7/00 27,710CC-7 7/02 24,300CC-7 Golf Adit 3,620

CC-6 9/90 420CC-6 2/02 417CC-6 5/03 Upstream of Iron Chest 534

CC-0 9/90 < 100CC-0 7/02 At Arkansas 08

Page 10: Mine Design, Operations & Closure Conference -2004

Mary Murphy Gold Mine—Chafee County, CO DISSOLVED ZINC CONCENTRATIONS

Location Date Conc. (ug/l)GW WellsMM-15 9/93 45MM-15 Bedrock 7/02 08

MM-11 9/93 188MM-11 7/00 210MM-11 7/02 179MM-11 Allurial 5/03 560

MM-3 9/93 17,131MM-3 7/00 15,830MM-3 2/02 21,500MM-3 Bedrock 5/03 5,570

MM-6 9/93 2605MM-6 7/02 13,700MM-6 Allurial 122,000

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Scope of Ground-Water Tracing

Mary Murphy Mine—Applied Research Site

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Results of Ground Water Tracing

Mary Murphy Mine

Page 18: Mine Design, Operations & Closure Conference -2004

Inverse Geochemical Modeling

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

Page 22: Mine Design, Operations & Closure Conference -2004

Delta O-18 in Selected Tributary Inflows, 1400 LevelMary Murphy Gold Mine

Page 23: Mine Design, Operations & Closure Conference -2004

Pre-event Water and Event Water in Total Discharge From 1400 PortalMary Murphy Gold Mine

Page 24: Mine Design, Operations & Closure Conference -2004

Tritium vs Delta O-18 Mary Murphy Mine Site (2002-2003)

-22.00

-20.00

-18.00

-16.00

-14.00

-12.00

-10.00

8 10 12 14 16 18 20

Tritium (TU)

Del

ta O

-18Surface Water

Alluvial Wells

Bedrock Wells

Snow

Mine Samples

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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 YRSMM 3 - 2-4 YRS

• MM 18 - 2-3 YRSMM 18 - 2-3 YRS

• MM 15 - ABOUT 8 YEARS OLDMM 15 - ABOUT 8 YEARS OLD

ALLUVIAL WELLS• MM11 - 3-4 YRSMM11 - 3-4 YRS

Source – A. Manning -USGSSource – A. Manning -USGS

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