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