Grouse Creek, Idaho; Site Reclamation and Long-Term Water Management

Grouse Creek Mine in central Idaho operated from 1994 to 1997 when it shutdown due to low metal prices. In 2000 the site went into permanent closure status, and the tailings impoundment came under CERCLA authority. Three Actions were identified for the project; 1) capture and contain contaminants, 2) dewater tailings impoundment, and 3) final reclamation and closure of the impoundment. Contaminants were captured and contained through a series of sumps and wells. Dewatering began in 2003, and by the end of 2007, approximately 1 billion gallons of water have been discharged. Reclamation of the impoundment will begin in 2008.

Approximately 60% of the site has been reclaimed. The Waste Rock Storage Facility had an engineered cover placed in 1998. Exploration roads and haul roads have been removed. Disturbed slopes have been regraded, topsoil placed and hydro seeded. More than 20,000 trees and shrubs have been planted.

Reclamation of the tailings impoundment is expected to be completed in 2010. The southern portion of the reclaimed impoundment surface will be a floodway for storm water discharge and the north end will serve as a polishing pond for water potentially treated through passive technology. The two segments of the impoundment will be hydraulically separated to prevent mixing treated waters with storm water.

Passive treatment pilot studies have successfully operated through several years, including winter months. It is hoped that passive treatment will be a part of long term water management at the Grouse Creek Unit. Initial evaluations indicate that a sulfate reducing bioreactor with aerobic polishing will meet current NPDES effluent limits during most months excluding spring runoff. An investigation will be conducted in 2009 to determine if passive treatment in combination with a lime pre-treatment technology such as Aqua-fix will suffice to meet effluent limits during those runoff periods.