U.S. Department of the Interior U.S. Geological Survey Acid-rock drainage at Skytop, Centre County, Pennsylvania, 2004 by Jane M. Hammarstrom1, Keith Brady2, and Charles A. Cravotta III3 Open-File Report 2005-1148 Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government 1 U.S. Geological Survey, 954 National Center, Reston, VA 20192
[email protected] 2 PA Department of Environmental Protection, PO Box 8461, Harrisburg, PA 17105 3 U.S. Geological Survey, 215 Limekiln Road, New Cumberland, PA 17070 Preface Construction along Interstate Highway 99 during 2003 exposed sulfidic rock within a fresh roadcut on Bald Eagle Mountain at Skytop, near State College, in Centre County, central Pennsylvania. The cut exposed pyrite veins associated with an unmined, sandstone-hosted, zinc-lead deposit. Excavated rock was crushed and used locally as road base and fill. Within months, acidic (pH<3), metal-laden seeps and surface runoff from the crushed rock piles and roadcut raised concerns about surface- and ground-water contamination and prompted a halt in road construction and the beginning of costly remediation. The Pennsylvania Department of Transportation (PennDOT) and the Pennsylvania Department of Environmental Protection expanded their site investigations and monitoring in response to the acid-drainage problem to determine the extent of the environmental effects at Skytop and to develop long-term remediation strategies. In addition, those agencies sought information on the source of the acid drainage and on the processes that led to the formation of acid-rock drainage at Skytop to assist them in selecting appropriate remediation for Skytop and in avoiding similar problems in other areas.