It’s all about the Money
Acid Mine Drainage (AMD) is naturally occurring water that continues draining from mines after they are closed. This water usually has high concentrations of heavy metals and a low pH. This water will flow for centuries and needs to be treated before it mixes with surface water.
Many of the mines that caused this drainage are closed so there is no responsible party. Many states and the EPA have set aside trust funds to treat this waste water from some of these sites. Existing mines are required to set up treatment plants and establish trust funds for operation of the treatment system before mine closure.
This worked for many years until interest rates dropped. The amount of interest on the trust fund was insufficient to operate the plants. The plants had to dip into the principal to pay operating costs. This paper outlines what was done to reduce costs and the problem that the changes caused.
See more of this Group/Topical: Topical 7: 19th Topical Conference on Refinery Processing