SCRUBGRASS
The Scrubgrass mine drainage treatment system was renovated to improve its treatment effectiveness, lessen long-term O&M costs, and improve its use as an educational facility. The system consists of a deep mine discharge, an electric aerator, and two ponds. Both ponds were full of iron sludge. The sludge was removed and captured on-site in geotextile bags. Iron Oxide Recovery, Inc., financed the iron recovery aspect of the project and is currently marketing the material as a pigment. Its pigment value was substantially decreased by the unavoidable mixture of mud with the iron sludge during its removal from the pond. The ponds were deepened by two feet to increase the system volume from 278,000 gallons to 467,000 gallons. Retention time for average flow increased from at most 10 hours (pre-project conditions) to 42 hours. Soils excavated from the ponds were disposed of off-site at a local soils recycling operation. The ponds were lined with a geotextile fabric and 12 inches of AASHTO #1 aggregate were placed on the bottoms. The aggregate bottom will support heavy equipment used in future sludge recovery operations. The geotextile fabric will prevent contamination of recovered iron with underlying clays, increasing its purity and saleability. The influent channel to the upper pond was extended to eliminate a short-circuiting problem. A limestone aggregate path was installed between the site entrance, the aerator, and the final discharge. A guard rail and gate were placed at the site entrance to prevent unauthorized or accidental access by vehicles. A four-foot chain link fence was placed between the path and the ponds.
The modifications only improved the system's treatment effectiveness by about 30%. Performance may improve with growth of the wetland plants in 2004. We are working with the aerator contractor to assure its optimal performance.
An operation and maintenance plan was developed. Iron Oxide Recovery, Inc., has agreed to take over routine site O&M and sludge management responsibilities in return for ownership of all sludge removed. This is the first case where long-term system O&M responsibilities have been traded for resources recovered from the polluted mine water.
