Remediation of Abandoned Mine Sites Using Constructed Wetlands: A Colorado Perspective

Abstract

In recent years, constructed wetlands have been used to remediate acid mine drainage which has resulted from both coal and metal mining activities. These wetlands are used in conjunction with other engineered components to create a passive mine drainage treatment system (PMDT). Passive systems are designed to remediate mine drainage using minimum capital expenditures and little to no operational and maintenance costs. The Colorado Division of Minerals and Geology (DMG) is responsible for the design, construction, and operation of constructed wetlands in Colorado. Only 5 systems are in existence at this time, located in terrain varying from gentle foothills to remote, sub-alpine mountains. The design of a wetland system is based on a multitude of factors such as site terrain and access, mine drainage composition, and in the Rocky Mountain region, altitude. The salient design issues associated with each wetland system will be presented and discussed. The impact of altitude, climate, terrain, and other physical site constraints on each wetland design will be discussed. In addition, chemical issues critical to the design of each wetland such as pH and alkalinity will be presented. Finally, the performance of each wetland system will be examined.Additional Key Words: passive mine drainage treatment system, anoxic limestone drain, sulfate reducing wetlands.

Scientific Soundness and Socio-Economic Realities in Reclamation for Habitat

“…Constructed wetlands for the purpose of treating contaminants are a case in point (Ganse and Herron 1995). Both the treatment of a contaminant and the construction of a wetland should be viewed as contributing to a broader ecosystem objective in order to determine how much treatment is sufficient and which alternative methods to utilize.…”