Mining Program - Region 5 Success Stories
The Irish Hill Mine, Amador County

The Irish Hill Mine, Amador County

  Photographs of Mine Site

Irish Hill Mine is an abandoned former copper mine that operated in the 1860s. The property is currently owned by Amador Ranching Associates.  Prior to the current remediation effort, the site contained two large, partially treated and covered mine waste containment areas, several smaller deposits of untreated waste and two impoundments with contaminated sediments.  Drainage from the site was acidic with elevated metal concentrations leached from inadequately treated and covered mine waste. 

The major problem with the site is acid mine drainage.  The waste contains high concentrations of ferrous sulfide which can oxidize and form sulfuric acid in the presence of water and oxygen.  Acidity of the waste precluded vegetation cover and the poorly graded slopes resulted in excess erosion of cover soils and waste.

The current owners proposed to voluntarily remediate the site.  The re-closure involved removing waste from untreated areas and contaminated sediments in the impoundments; treating the waste and sediments with dolomite; consolidating the treated material in the north containment area; and re-grading and covering both the north and south containment areas.  After the addition of the top soil, the area was replanted to prevent erosion. The site’s pH has returned to background levels.

This site is a success because the proper treatment of the mine waste and revegetation of the site returned the site's pH and other factors to the background levels.