De Sale Restoration Area, Slippery Rock Watershed, PA
PA Voluntary Cleanup
PA Voluntary Cleanup
IMAGE GALLERY
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Click on images
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AMD Damage
Restored Conditions
Cleanup Objectives: Treat acid mine drainage (AMD) from abandoned surface and underground coal mines in western Pennsylvania
Green Remediation Strategy: Employ a sequential series of natural gradient-driven engineering steps involving settling ponds, vertical-flow ponds, and constructed wetlands to passively treat AMD
- Uses a 16- by 3-foot instream dam to collect contaminated stream water
- Diverts collected water to an 80,000-square-foot forebay to settle solids and debris
- Passes the partially settled water into parallel, flushable vertical-flow ponds constructed of limestone and spent mushroom compost to neutralize acidity, raise pH, and remove metals
- Transfers water next to a horizontal 0.2-acre, 5-foot-deep pond for additional settling
- Passes settled water to a 1.5-acre free-flowing, aerobic constructed wetland for precipitation of amorphous iron hydroxides
- Transfers the wetland water to a horizontal-flow limestone bed to remove and recover manganese and provide additional alkalinity
- Returns treated water to a rock-lined channel emptying into the watercourse approximately 1,000 feet downgradient of the intake point
Results:
- Uses natural intrinsic energy for operation of the multi-step treatment process
- Avoids air emissions associated with consumption of grid electricity during water treatment
- Uses passive-energy biological processes for treatment "finishing steps"
- Returns treated water to its natural hydraulic course
- Obtained limestone aggregate from a quarry three miles away, at a material and delivery cost of $12 per ton
- Obtained spent mushroom compost from an agricultural producer 12 miles away, at a material and delivery cost of $10 per cubic yard
- Completed construction of the treatment system within six weeks, with help from local volunteers, academic students, and mining companies and coordination by the (non-profit) Slippery Rock Watershed Coalition
- Neutralizes approximately 180 pounds of acid discharge each day
- Achieves 100% neutralization of the acid discharge and 99%, 99%, and 70% reductions of iron, aluminum, and manganese concentrations, respectively , as compared to intake levels
- Recovered 30 tons of material (containing approximately 25% manganese oxide) over eight years of operation
- Derives funds for future AMD treatment systems through sale of recovered manganese and iron oxides to artists or manufacturers specializing in green products
Property End Use: Natural resource conservation area under state programs
Point of Contact: Scott Roberts, PA Department of Environmental Protection
