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Water Quality Changes in Above-Drainage Upper Freeport and Pittsburgh Coal Mines in WV

This study examines the changes in water quality over time in above-drainage upper Freeport and Pittsburgh coal mines in West Virginia. It analyzes the pH levels and acidity concentrations and compares them to historical data. The findings show a decrease in acidity of 2.1% annually in Pittsburgh mines and 2.4% annually in Upper Freeport mines. The study also discusses the impact of the initial flush of mine closure on decay rates.

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Water Quality Changes in Above-Drainage Upper Freeport and Pittsburgh Coal Mines in WV

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  1. Water Quality Changes Over Time inAbove-Drainage Upper Freeport and Pittsburgh Coal Mines in West Virginia Ben Mack, Jeff Skousen, Louis McDonald, and Dorothy Vesper West Virginia University

  2. - Major pollutant - Pyritic rocks

  3. Mine type Above-drainage vs. Below-drainage

  4. Below-drainage - 10 - 40 years - Type 1 - initial flush of mine - first 10 years after mine closure - Type 2 - continued pyrite oxidation • Below – drainage mines • - 25 years between samples • - pH from 3.0 to 6.1 Younger (1997)

  5. Above – drainage mines • - 25 years between samples • - pH from 3.0 to 3.5 Lambert and Dzombak, 2000

  6. Annual % decrease of 2 and 3% from the previous year

  7. Determine changes in acidity concentrations of 40 above-drainage, underground mines over 38 years using decay rates

  8. Historic sampling • 1968 - EPA - 555 sites • 1980 - WV DNR - 20 sites • 2000 - WVU - 40 sites • 2006 - WVU - 40 sites • Graphs of acidity vs. time for 6 Pittsburgh and 34 Upper Freeport (UF) sites

  9. Acidity collection

  10. Compare to T&T #2 - Closed in 1996 - Different decay rate?

  11. % decrease of acidity per year

  12. % of initial concentration vs. time (exponential decay) Exponential decay: C/C0=e-kt C/C0=e-.02t C/C0=e-.05t C/C0=e-.10t

  13. 1968 Sampling 2006 sampling • Pitts. exp. decay constant (k) = -0.044 • Estimated initial acidity = 9,113 mg/L as CaCO3 (3.86 relative acidity)

  14. UF exp. decay constant (k) = -0.054 • Estimated initial acidity = 5,413 mg/L as CaCO3 (4.01 relative acidity)

  15. Acidity at time of closure = 1,128 mg/L as CaCO3 • T&T exp. decay constant (k) = -0.104 • Increased decay rate due to first flush

  16. Conclusions • Pittsburgh and UF mines showed a 2.1% annual decrease in acidity

  17. Pitts. mines - Pitts. decay rate constant = -0.044 - Estimated initial acidity = 9,113 mg/L as CaCO3 (3.86 relative acidity) • UF mines - UF decay rate constant = -0.054 - Estimated initial acidity = 5,211 mg/L as CaCO3 (4.01 relative acidity)

  18. T&T #2 - T&T decay rate constant = -0.104 - Increased decay rate due to first flush

  19. Questions?

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