Variability of Coal Mine Drainage in Pennsylvania Resulting from Coal Mining Practices and Geology

1,261 views

Published on

Terry Schmidt P.E., Skelly and Loy, “Variability of Coal Mine Drainage in Pennsylvania Resulting from Coal Mining Practices and Geology”

Mining methods employed can have a significant impact on resulting mine drainage characteristics. Also, the hydrologic regime and the individual coal seams as well as the geology above and directly below. These factors in combination can affect coal mine drainage quality in a variety of ways and will be reviewed with site specific examples within the primary coal regions of Pennsylvania.

Published in: Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,261
On SlideShare
0
From Embeds
0
Number of Embeds
228
Actions
Shares
0
Downloads
17
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Variability of Coal Mine Drainage in Pennsylvania Resulting from Coal Mining Practices and Geology

  1. 1. Variability of Coal Mine Drainage in Pennsylvania Resulting from Coal Mining Practices and Geology Terry W. Schmidt • Presented at Pennsylvania Abandoned Mine Reclamation Conference, August 10, 2013. • Terry W. Schmidt, P.E., Vice President, Engineering, Skelly And Loy, Inc., 2601 North Front Street, Harrisburg, PA 17110.
  2. 2. Presentation Promises • No formulas • Few technical terms - (keep it simple) • Lots of pictures • Mostly generalizations - (won’t dwell on exceptions)
  3. 3. AMD Formation Pyrite (sulfur) + Oxygen + Water + Bacteria = AMD (Coal Mine Drainage)
  4. 4. Pennsylvania Coal Fields Source: USGS
  5. 5. Anthracite Regional History • Mid-1800’s – coal was extensively mined – fueled America’s industrial revolution – coal became the economic base of the region • Post-1917 – coke replaced anthracite in steel-making – demand for anthracite coal declined – coal-related employment declined • 1950’s – many remaining active mines were flooded – major underground mining operations ceased – coal industry & regional economy collapsed within a short time
  6. 6. Typical Anthracite Geology
  7. 7. Typical Anthracite Cross Section
  8. 8. Whaleback Whaleback
  9. 9. ANTHRACITE MINING • Underground Mining – Breast and Pillar – Room and Pillar – Retreat Mining • Surface Mining – Contour Mining – Open Pit
  10. 10. Anthracite Breast and Pillar Mining
  11. 11. Anthracite Underground Mining
  12. 12. Anthracite Open Pit Mining
  13. 13. Contour Style Surface MiningContour Style Surface Mining
  14. 14. Actual Cross Section Through Porter and Tower City Tunnels
  15. 15. Geology - Pit Near Porter Tunnel Schuylkill County
  16. 16. Porter Tunnel Characteristics • Flow 700 – 7,000 gpm • 3 pH • 100 mg/L acidity • 20 mg/l iron • Low Al and Mn
  17. 17. Bear Creek, Lykens Tunnel, Dauphin County Bear Creek, Lykens Tunnel, Dauphin County
  18. 18. Bear Creek, Lykens Drift Dauphin County
  19. 19. RT 309 Tamaqua, Schuylkill County RT 309 Tamaqua, Schuylkill County
  20. 20. Nanticoke Creek, Luzerne County Nanticoke Creek, Askam Borehole, Luzerne County
  21. 21. Eastern Middle Anthracite Region • 33 square-miles mining – 13 rock tunnels • 120 square-mile surface drainage area • Spans Carbon, Columbia, Luzerne, and Schuylkill Counties
  22. 22. Cross Section in the City of Hazleton
  23. 23. Jeddo Tunnel Jeddo Tunnel 9 feet wide 7 feet high 30,000 GPM
  24. 24. Anthracite Summary • Highly variable geologic structure • Low levels of sulfur minerals (OB & coal) • Tunnel/borehole control of water levels • Vast interconnected mining complexes • Higher discharge flows • Lower acidity and metal concentrations • Discharge locations often near stream
  25. 25. BITUMINOUS MINING OPERATIONS • Underground Mining – Room and Pillar – Longwall • Surface Mining – Contour Mining – Area Mining
  26. 26. Typical Bituminous Geology
  27. 27. Area Dragline Mining
  28. 28. Area Dragline Mining
  29. 29. Contour and Area Mining Reclamation
  30. 30. Bituminous Surface Mining Somerset County
  31. 31. Bituminous Underground Bituminous Underground
  32. 32. PROJECT LOCATION MAP
  33. 33. Down Dip versus Up Dip, Clearfield County Yorkshire #1 (down dip) • Clarion “A” seam coal • 10 degree dip (S/SE) • Completed 1942 • 540 acres • 50 % coal recovery • 3% sulfur in coal • 300’ maximum to surface • 2 discharges Shoff Mine (up dip) • Clarion “A” seam coal • 10 degree dip (S/SE) • Completed late 1930s • 428 acres • 35-100% coal recovery • 3% sulfur in coal • 300’ maximum to surface • 5 discharges
  34. 34. Down Dip versus Up Dip Yorkshire #1 (down dip) • 90% workings inundated • 129 mg/L acidity • 107 mg/L iron • 1,009 mg/L sulfate • 7.3 mg/L aluminum Shoff Mine (up dip) • <10% workings inundated • 1,408 mg/L acidity • 365 mg/L iron • 1,398 mg/L sulfate • 6.8 mg/L aluminum
  35. 35. Cold Stream • Watershed Area of 21 Square Miles • Over 10 miles Length in Centre County • Extensive Mining in Lower 2.5 Miles • Over 30 Known Underground Mine Openings along Cold Stream • Upper Reach Classified as High Quality Cold Water Fishery (HQ-CWF) • Lower Reach Supports NO Fishery
  36. 36. Glass City, Cold Stream Centre County FLOW RATE: 0 – 1400 gpm TOTAL IRON: 40 – 50 mg/L pH: 2.5 – 3.0 NET ACIDITY: 400-500 mg/L MANGANESE: 1 – 7 mg/L SULFATES: 100 – 600 mg/L ALUMINUM: 15 – 25 mg/L
  37. 37. Cold Stream, Mine Drift, Centre County Cold Stream, Mine Drift, Centre County
  38. 38. Hubler Run Clearfield County Raw water quality – Q AVG = 19 GPM – Q MAX = 45 GPM – Average Acidity = 115 mg/L – Average iron < 1 mg/L – Average Aluminum = 17 mg/L
  39. 39. Elk Creek, Elk County Average Raw AMD: Flow = 10 gpm pH = 5.5 Fe = 15 mg/L Acidity = 100 mg/L
  40. 40. St. Michael Discharge, Cambria County • primary discharge emanates from the St. Michael Shaft located along Topper Run • represents the largest pollutant loading to the Little Conemaugh River • shaft extends 600 feet to the Lower Kittanning Coal Seam • results from artesian pressure in the mine pool
  41. 41. DISCHARGE CHARACTERISTICS • Flow rates range from 2,000 to 4,000 gallons per minute (GPM) • Unites States Geologic Survey (U.S.G.S.) sample data indicated: - dissolved oxygen = 0.4 milligrams per liter (mg/L); - field pH = 5.4; - acidity = 380 mg/L; - aluminum = 0.6 mg/L; and - iron = 174 mg/L.
  42. 42. Cessna Run, Indiana County • Average Raw AMD: • Flow = 90 gpm • pH = 5.5 • Al = 6 mg/L • Fe < 2 mg/L • Acidity = 120 mg/L
  43. 43. Blacklegs Creek #7 Indiana County Average Raw AMD: Flow = 800 gpm Fe = 1 mg/L Al = 15 mg/L Hot Acidity = 150 mg/L
  44. 44. Blacklegs Creek #8 Drainage Tunnel, Indiana County
  45. 45. Blacklegs Creek Kolb Indiana County
  46. 46. Kolb Site • Located in Indiana County, Pennsylvania • Abandoned underground mine discharge • High flow (approximately 1,000 gallons per minute) • DO concentration at the underground mine was typically less than 1 mg/L • Elevation drop of 40 feet from the mine discharge to treatment location
  47. 47. Boyce Park, Allegheny County • BP 2 • pH = 4.8 • Fe < 1.0 mg/L • Al = 24 mg/L • acidity = 77 mg/L • BP 3 • pH = 3.3 • Fe = 4 mg/L • Al = 23 mg/L • acidity = 265 mg/L • BP 4 • pH = 4.8 • Fe = 17 mg/L • Mn < 1.0 mg/L • Al = 79 mg/L • acidity = 488 mg/L
  48. 48. Dunkard Creek – Greene County Site 2A: Flow = 35 gpm pH = 3.7 Fe = 25 mg/L Al = 23 mg/L Hot Acidity = 220 mg/L
  49. 49. Dunkard Creek – Greene County Site 2B Flow = 390 gpm pH = 3.1 Fe = 41 mg/L Al = 33 mg/L Hot Acidity = 380 mg/L
  50. 50. Dunkard Creek – Greene County
  51. 51. Sagamore Site • Located in Fayette County, Pennsylvania • First documented use of a windmill aerator at a passive treatment system • Two discharges treated with a flow rate of 100 gpm • Net-alkaline with iron concentrations of 15 to 20 mg/L • Little elevation drop
  52. 52. Broad Top Township, Bedford County
  53. 53. Broad Top Township, Bedford County  Over 80 identified AMD discharges  Flows <1 - >500 GPM, highly variable chemistry  30 passive treatment systems (10% of PA systems)  Three 303(d)-listed watersheds (28 square miles): -Longs Run, Six Mile Run, Sandy Run  Historic underground mining (approx. 184 mine entries) and surface coal mining legacy of isolated Broad Top coal field since the 1800’s  Abandoned underground mines filled with water and drainage from partially reclaimed surface mines have created AMD throughout the Township
  54. 54. Finleyville – Primarily Aluminum
  55. 55. LR0-D14: Primarily Iron AMD Discharge Longs Run Aerobic Wetland (0.1 acre) Net alkaline discharge with moderate flow and high Fe2+ , but very limited space removes ~ 50% of iron; wetland was slightly enlarged & Aero-Troff added to promote aeration in place of rock-lined channel
  56. 56. LR0-D10: VFW w/ Automatic Inline Structures LR0-D10 , flow = 30 gpm acidity = 440 mg/L, Fe = 145 mg/L, Al = 10 mg/L System Constructed in 2006, Performed One Compost O&M Event Since 2006 on VFW
  57. 57. SX0-D8 Before Treatment
  58. 58. SX2-D5: Preliminary Construction Exposed Mine Entry/Source of AMD
  59. 59. SX0-D6: Exposed Buried Mine Entries – Two?
  60. 60. SX0-D16 Exposed Mine Entry Average Raw AMD: Flow = 50 gpm pH = 3.2 Fe = 1.0 mg/L Al = 6.3 mg/L Hot Acidity = 107 mg/L
  61. 61. SX0-D16 Passive AMD Treatment System Using FLBs & Settling Ponds Final Outfall (Aug 2009): pH = 7.7 Fe = <0.1 mg/L Al = 0.2 mg/L Hot Acidity = -26 mg/L Alkalinity = 38 mg/L
  62. 62. SX8-D1 • flow = 120 gpm • pH = 3.5 • Al = 2 mg/L • Fe = 30 mg/L • Acidity = 125 mg/L
  63. 63. SA0-D4 VFW-Based Passive Treatment Average Raw AMD: Flow = 25 gpm pH = 3.0 Fe = 99 mg/L Al = 38 mg/L Hot Acidity = 476 mg/L
  64. 64. SA0-D5: Exposed Vertical Shaft Average Raw AMD: Flow = 70 gpm pH = 3.1 Fe = 15 mg/L Al = 16 mg/L Hot Acidity = 195 mg/L
  65. 65. Bituminous Summary • Flatter lying geologic structure • Variable sulfur mineral levels (OB & coal) • Groundwater control of water levels • More smaller mining complexes • Lower discharge flows • Higher acidity and metal concentrations • Variable discharge locations
  66. 66. PA Coal Mine Discharge Comparison Bituminous • Regular Geology • Variable Sulfur Content • GW/Entry Control • Isolated UG Complexes • Lower Discharge Flows • Higher Contaminant Levels • Discharge locations vary Anthracite • Complex Geology • Lower Sulfur Content • Tunnel/Borehole Control • Vast UG Complexes • Higher Discharge Flows • Lower Contaminant Levels • Discharges near streams
  67. 67. Factors Influencing Coal Mine Drainage • Availability of sulfur bearing minerals - coal, overburden, bottom rock • Availability of water - rainwater, groundwater • Availability of oxygen - inundation, fluctuation in water levels • Availability of bacteria
  68. 68. AMD Formation Pyrite (sulfur) + Oxygen + Water + Bacteria = AMD (Coal Mine Drainage)
  69. 69. Comments Or QuestionsComments Or Questions

×