The Formation of Abandoned Mine Drainage

1. The Formation of Abandoned Mine Drainage The Definition and Causation of Abandoned Mine Drainage Lessons Prepared by Trout Unlimited With Funds from Pennsylvania Department of Environmental Protection

2. Prior to 1977 • Prior to the Surface Mining Control and Reclamation Act (SMCRA) there were no federal regulations on mining • This allowed mining companies to simply abandon a mine when they completed their mining • Most mines prior to 1977 produced some degree of abandoned mine drainage (AMD)

3. Prior to 1977 • With approximately 5,500 miles of impacted waterways in the state of Pennsylvania AMD is the leading source of non-point source pollution • The impacts of these mines which can be hundreds of years old are still seen and felt today

4. AMD in the Clearfield Creek Watershed. Provided by Clearfield Creek Watershed Association. AML in the Kettle Creek watershed. Provided by TU staff. Abandoned Mines • Any area that is impacted by these mines are called Abandoned Mine Lands (AML) • Any water that is impacted by these mines is called Abandoned Mine Drainage (AMD)

5. Borehole into an underground deep mine that is filled with polluted water. Provided by TU Staff. A sinkhole formed as the roof of an abandoned mine collapsed. Provided by PA Department of Environmental Protection http://www.dep.state.pa.us/dep/deputate/minres/districts/homepage/california/Underground/Mine%20Subsidence/mine_subsidence.htm Inside an abandoned deep mine. Note the size of some of the rocks and fallen down wooden supports. Provided by Rich Wykoff. Abandoned Mines Lands • Deep Mines may look like caves, but they are dangerous! • There can be a subsidence of the mine as well as water coming out of bore holes!

6. Abandoned Mines Lands • Refuse piles (gob piles, culm banks, spoil piles, boney piles…) are left over coal and rock that was not able to be used All photos provided by the Western PA Coalition for Abandoned Mine Reclamation http://amrclearinghouse.org/Sub/photogallery/

7. Pits like these have been left by surface mining. Provided by Alder Run Engineering. A strip mine as seen from space. Generated using Google Earth. Highwalls like this one can be very high and steep. This highwall can be estimated to be 15-20 ft. high. Provided by TU Staff. Abandoned Mines Lands • Abandoned strip mines have no top soil left. Therefore nothing grows in these areas • Historic strip mines also have dangerous pits and highwalls

8. Abandoned Mine Drainage • Metal-rich, generally acidic, water formed from a chemical reaction between water, oxygen and rocks containing sulfur-bearing minerals • Forms when mineral deposits that contain sulfides are uncovered during mining • Most common example is pyrite

9. Pyrite • Commonly known as ‘Fools Gold’ • Chemical formula: FeS2 • AMD is formed when pyrite, an iron sulfide, reacts with air and water • This forms sulfuric acid and ferric hydroxide Iron Pyrite. Provided Richard Kruse http://richardkruse.com/Misc_Photos/Minerals/Mineral_Pyrite_RK.jpg

10. Abandoned Mine Drainage Oxygen O2 Pyrite FeS2 Water H2O + + + + Ferric Hydroxide Fe(OH)3 Sulfuric Acid H2SO4 +

11. Abandoned Mine Drainage

12. This mine pool (shown in purple) gives an idea of size, this pool actually has currents and flow. Provided by Office of Surface Mining http://www.arcc.osmre.gov/Divisions/TSD/Techservices/Hydrology/hydrology.shtm#MPFM Mine Pools • Mines can be come filled with water called a mine pool if this water breaks out it can be dangerous

13. AMD Formation Reaction Step One: The pyrite oxidizes upon contact with air and water Fe+2 + 1/4 O2 + H+ --> Fe+3 +1/2 H2O

14. AMD Formation Reaction Step Two: Iron oxidizes to ferric iron FeS2 + 7/2 O2 + H2O --> 2SO4-2 + Fe+2 + 2H+

15. AMD Formation Reaction Step Three: Precipitation occurs with ferric iron to ferric hydroxide Fe+3 + 3H2O --> Fe(OH)3 + 3H+

16. AMD Formation Reaction Step four: All combined to show a full formation of sulfuric acid FeS2 + 15/4 O2 + 7/2 H2O --> 2H2SO4 + Fe(OH)3 4

17. AMD Characteristics • Low pH- Typically 3-4, but can be lower • High Acidity • Low Alkalinity • High metals- Iron, Aluminum and Manganese are the common metals in our area • High Sulfates- Caused by land disturbance such as mining • All of these lead to polluted and dead streams!

18. Water Chemistry • pH- A measure of hydrogen ions in water • Determines Acid or Base • Most healthy streams have a pH of 6-9 • Brook Trout can survive in pH 4.5-9.5 • AMD impaired waters can have a pH of 2-5 pH scale with common solutions. Provided by Jackson Bottom Wetland Preserve http://www.jacksonbottom.org/monitoring-restoration/water-quality-concepts/

19. Water Chemistry • Alkalinity- This is a measure of the stream’s ability to buffer pH changes • Alkalinity is added by the rocks a stream flows over, commonly limestone • The higher the alkalinity the more acid can be added before pH is affected

20. Water Chemistry Add 10 ml of Acid Add 10 ml of Acid 50 ml of water 50 ml of water Alkalinity Alkalinity pH Before is 7.0 pH Before is 7.0 pH After is 6.9 pH After is 6.0

21. Water Chemistry • Streams in areas highly impacted by AMD have little naturally occurring alkalinity • This means small quantities of acid impact these waters more than highly alkaline waters • What alkalinity they do have is quickly removed by the highly acidic water

22. Water Chemistry • Total Acidity- This is a measure of how many positive acidic ions are present • This is similar to pH, but it is a different measurement • This is mainly measuring the number of hydrogen ions, however other ions can affect this number

23. Water Chemistry pH 5 pH 7 Acidity 10 mg/l Acidity 15 mg/l Acidity 10 mg/l H+ H+ Cl- HCl H+ H+ H+ Cl- Cl- H+ H+ HCl Al3+ Cl- HCl Cl- Cl- Al3+ H+ Al3+ H+ Cl- Al3+ Cl- Cl-

24. Water Chemistry • Streams that have been impacted by AMD have high levels of acidity • One of the major source of acidity beyond hydrogen ions is aluminum ions, which are common in AMD

25. Water Chemistry • Iron- Some metals leach into water. Iron is a commonly found dissolved metal in our area • Iron becomes dissolved at very low pH’s • AMD impaired streams have high levels of iron from the reaction with pyrite, and from the soils • Dissolved iron is toxic in high levels, and the precipitated iron is deadly to creatures with gills Iron precipitate on stream bottom. Provided by TU Staff

26. Water Chemistry • Aluminum- Another commonly dissolved metal in our area • Aluminum is more dangerous at lower pH’s • Aluminum is common due to the soil types in Pennsylvania • The rule of thumb for aluminum is if the pH is less than 5.5 and the aluminum concentration is greater than 0.5 mg/l stream life will die! Aluminum precipitate in the water. Provided by TU Staff

27. Water Chemistry • Sulfates- Sulfates are naturally occurring but at high levels can be a sign of a problem • Sulfates are released when the soil is disturbed such as mining • Sulfates cause an unpleasant odor of rotten eggs

28. Water Chemistry • These drainages have the most impact on the small 1st order streams they enter • Most areas that have been mine have high concentrations of AMD impaired streams • This does not allow enough clean water to enter the system and dilute the impacted water

29. After the confluence with Brubaker Run, Clearfield Creek is left stained and lifeless. Provided by Clearfield Creek Watershed Association. Brubaker Run is highly polluted water that enters Clearfield Creek. Provided by Clearfield Creek Watershed Association. The upper sections of Clearfield Creek support life. Provided by Clearfield Creek Watershed Association. Clearfield Creek • In the headwaters of Clearfield Creek life thrives • Brubaker is not the first or last source of pollution entering Clearfield Creek, it is one of the worst sources of pollution and stains the stream • Brubaker Run enters Clearfield Creek leaving it virtually lifeless

30. Water Quality for Local Streams

31. Water Quality Impacts • The water quality impacts of these drainages are seen far downstream and inhibit some life for miles • There are treatment options for these drainages Anna S treatment system on Babb Creek. Generated using Google Earth.