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.

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. Presentation Promises
• No formulas
• Few technical terms
- (keep it simple)
• Lots of pictures
• Mostly generalizations
- (won’t dwell on exceptions)

3. AMD Formation
Pyrite (sulfur)
+
Oxygen
+
Water
+
Bacteria
=
AMD (Coal Mine Drainage)

4. Pennsylvania Coal Fields
Source: USGS

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. Typical Anthracite Geology

7. Typical Anthracite Cross Section

8. Whaleback
Whaleback

9. ANTHRACITE MINING
• Underground Mining
– Breast and Pillar
– Room and Pillar
– Retreat Mining
• Surface Mining
– Contour Mining
– Open Pit

10. Anthracite Breast and Pillar Mining

11. Anthracite Underground Mining

12. Anthracite Open Pit Mining

13. Contour Style Surface MiningContour Style Surface Mining

14. Actual Cross Section Through
Porter and Tower City Tunnels

15. Geology - Pit Near Porter Tunnel
Schuylkill County

16. Porter Tunnel Characteristics
• Flow 700 – 7,000 gpm
• 3 pH
• 100 mg/L acidity
• 20 mg/l iron
• Low Al and Mn

17. Bear Creek, Lykens Tunnel,
Dauphin County
Bear Creek, Lykens
Tunnel, Dauphin County

18. Bear Creek, Lykens Drift
Dauphin County

19. RT 309 Tamaqua, Schuylkill County
RT 309 Tamaqua,
Schuylkill County

20. Nanticoke Creek, Luzerne County
Nanticoke Creek, Askam
Borehole, Luzerne County

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. Cross Section in the City of
Hazleton

23. Jeddo Tunnel
Jeddo
Tunnel
9 feet wide 7
feet high
30,000 GPM

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. BITUMINOUS MINING
OPERATIONS
• Underground Mining
– Room and Pillar
– Longwall
• Surface Mining
– Contour Mining
– Area Mining

26. Typical Bituminous Geology

27. Area Dragline Mining

28. Area Dragline Mining

29. Contour and Area
Mining Reclamation

30. Bituminous Surface Mining
Somerset County

31. Bituminous Underground
Bituminous Underground

32. PROJECT LOCATION MAP

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. 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. 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

37. 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

38. Cold Stream, Mine Drift,
Centre County
Cold Stream,
Mine Drift,
Centre County

39. 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

40. Elk Creek, Elk County
Average Raw AMD:
Flow = 10 gpm
pH = 5.5
Fe = 15 mg/L
Acidity = 100 mg/L

41. 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

42. 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.

43. 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

44. Blacklegs Creek #7
Indiana County
Average Raw AMD:
Flow = 800 gpm
Fe = 1 mg/L
Al = 15 mg/L
Hot Acidity = 150 mg/L

45. Blacklegs Creek #8 Drainage Tunnel,
Indiana County

46. Blacklegs Creek Kolb
Indiana County

47. 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

48. 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

49. 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

50. 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

51. Dunkard Creek – Greene County

52. 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

54. Broad Top Township,
Bedford County

55. 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

57. Finleyville – Primarily Aluminum

58. 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

59. 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

60. SX0-D8 Before Treatment

61. SX2-D5: Preliminary Construction
Exposed Mine
Entry/Source of AMD

62. SX0-D6: Exposed Buried Mine
Entries – Two?

63. 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

64. 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

65. SX8-D1
• flow = 120 gpm
• pH = 3.5
• Al = 2 mg/L
• Fe = 30 mg/L
• Acidity = 125 mg/L

66. 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

67. 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

68. 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

69. 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

70. 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

71. AMD Formation
Pyrite (sulfur)
+
Oxygen
+
Water
+
Bacteria
=
AMD (Coal Mine Drainage)

72. Comments Or QuestionsComments Or Questions