Designing, Permitting, and Constructing a Biobarrier to Treat Acid Mine Drainage from the Historic Gibson Mine(Abstract)

摘要

Acid mine drainage (AMD) is caused when rain or groundwater flows over or through sulfur-bearing materials, forming solutions of net acidity that contain very high concentrations of acids, sulfates, and metals. Regardless of its origin, AMD needs to be intercepted as close as possible to the point of origin and treated before it contaminates surface-water bodies and/or reaches groundwater. The historic Gibson Mine (circa 1903) was an underground copper mine in the Globe-Miami district of Arizona with vertical shafts and horizontal tunnels (adits) that intercepted the ore body. The adits were developed for gravity removal of excessive water accumulated in the mine. AMD generated at the Gibson Mine contains sulfate together with metals and is polluting an adjacent tributary that feeds to Mineral Creek, a protected stream within the Gila River Watershed. The site’s remoteness demanded a technology with low operation and maintenance requirements, which led to the selec- tion of a passive Permeable Reactive Drain (PRD) biobarrier. The PRD biobarrier employs sulfate-reducing bacteria (SRB) that utilize organic electron-donating substrates to reduce sulfate to sulfide.