icgge 2003 mike wireman us epa region 8 303-312-6719 [email protected]
TRANSCRIPT
ICGGE 2003Mike WiremanUS EPA Region [email protected]
“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
Chalk Creek Mining District-Collegiate Range, CO
Mary Murphy Gold MineApplied 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
Mary Murphy Gold Mine—Applied Research SiteSite 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
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
Focus Of This Talk
> Metals Loading > Stream & Ground-Water Tracing
> Hydrometrics / Isotopic Results
Geology and Mine FeaturesMary Murphy Mine &
Vicinity
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.
Mary Murphy Gold Mine—Chafee County, CO DISSOLVED ZINC CONCENTRATIONS
Location Date Conc. (ug/l)GW WellsMM-3 9/93 17,131MM-3 7/00 15,830MM-3 2/02 21,500MM-3 5/03 5,570 MM-11 9/93 188MM-11 7/00 210MM-11 7/02 179MM-11 5/03 560
MM-6 9/93 2605MM-6 7/02 13,700MM-6 122,000
MM-15 9/93 45MM-15 7/02 08
Mary Murphy Gold Mine—Chafee County, CO DISSOLVED ZINC CONCENTRATIONS (CONTINUED)Location Date Conc. (ug/l)Chalk CreekCC-0 9/90 < 100CC-0 7/02 08
CC-6 9/90 420CC-6 2/02 417CC-6 5/03 534
CC-7 9/90 18,000CC-7 7/00 27,710CC-7 7/02 24,300CC-7 3,620
CC-7D 9/90 110CC-7D 7/02 44CC-7D 5/03 53.2
CC-9 9/90 < 100CC-9 7/00 118CC-9 7/02 24CC-9 5/03 35.2
Scope of Ground-Water Tracing
Mary Murphy Mine—Applied Research Site
Results of Ground Water Tracing
Mary Murphy Mine
Inverse Geochemical Modeling
Variation of Discharge Components Versus Time in 1400 Level.Mary Murphy Gold Mine
Isotopic Composition of WatersMary Murphy Gold Mine
Delta O-18 in Selected Tributary Inflows, 1400 LevelMary Murphy Gold Mine
Pre-event Water and Event Water in Total Discharge From 1400 PortalMary Murphy Gold Mine