Acid Mine Drainage Projects

Mill Run PLB
Rail Road Street SAPS
Other AMD Projects with GCWA Involvement


Mill Run PLB

The Pulse Limestone Bed system uses innovative acid mine drainage (AMD) treatment technology, which earned the George’s Creek Watershed Association the prestigious Conservation Service Award for implementing. The award was presented at a ceremony held at the Department of Interior headquarters on February 2, 2005.

Pressurized pulsed limestone beds allow the use of limestone (calcium carbonate) to neutralize acidic waters.  The AMD treatment process, based on limestone neutralization, has been developed and patented at the Leetown Science Center in Kearneysville, West Virginia. Limestone is used for acid neutralization because of its availability, low cost, and non-corrosive nature.  The risk of overtreatment of impaired waters is low. The limitations associated with limestone use; slow dissolution rate and armoring (formation of an impervious coating on the limestone surface) can be avoided and the rate of limestone reaction increased by use of pulsed fluidized bed reactor technology, combined with pressurization of the reactor with carbon dioxide. Pulsing of the limestone bed allows for vigorous mixing of the limestone sand, resulting in high attrition rates, helping keep the limestone surface clean. The carbon dioxide increases the rate and extent of limestone dissolution, decreasing retention time by a factor of 100 or more. This enhancement of limestone neutralization allows for much wider use of the more economical limestone than was previously thought possible. Waters containing up to 1000 mg/L acidity and 200 mg/L iron have been successfully treated with the process. The pulsed limestone bed (PLB) technology was recognized in 2001 with a Federal Laboratory Consortium (FLC) Technology Excellence award. Thus far the technology has been tested on several samples of coal mine drainage in Maryland and Pennsylvania, and has performed well.

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Railroad Street SAPS

Successive Alkalinity Producing Systems change the chemistry of the acid mine drainage (AMD) through the use of limestone and compost material.  AMD with ferric iron and dissolved oxygen concentrations are converted into anoxic AMD with concentrations of ferrous iron by creating a reducing environment.  As the compost material decays, the Biological Oxygen Demand is raised, all dissolved oxygen in the system will be consumed, and ferric iron will be converted to ferrous iron.  By changing the chemistry of the AMD, the AMD can then be passed through a bed of limestone to increase the bicarbonate alkalinity, without the limestone being smothered or armored with a coat of precipitating ferric iron.  Oxidizing ponds are installed to collect the metal precipitates.  This technology is suited to the site and is incorporated into the Rail Road Street Mine Drainage Remediation Design. 

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Other AMD Projects with GCWA Involvement

1) Getson Steel Slag Leach Bed
2) Fazenbaker SAPS

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