In September, Friends of Blackwater has hired Langan, Inc. and Hedin Environmental to design a replacement for the wetland anoxic limestone drain (WALD) mine drainage treatment system, just downstream of the FOB office, on the North Fork of the Blackwater. The WALD was an experimental system that was installed to treat acid mine drainage entering the North Fork back in the ‘90s. The original WALD failed within a few years of being built, but our replacement system will deliver more lasting benefits.
Both companies have multiple years of experience in the realm of acid mine drainage treatment, with truly innovative projects in their portfolios. Check out the Pittsburgh Botanic Garden’s website “A Reclamation Story” for an amazing example of one such project.
The basic design of the new North Fork system is two to four drainable limestone beds installed in parallel, plus a pair of settling ponds. Friends of Blackwater initially proposed a series of limestone leach beds, but were convinced that drainable limestone beds offered superior performance and lower long-term costs.
Months of design work lie ahead, and navigating the labyrinth of regulations and permits needed to bring such a project into existence is no easy task, but we, the Monongahela National Forest and our engineering partners are all excited about the potential of the project. While it won’t solve all the North Fork’s problems, this treatment system is a promising first step on the road to recovery for the North Fork.
The illustration above demonstrates how water will circulate through the system. Periodically flushing and draining the limestone bed will prevent the limestone from becoming plated with minerals.
The pictures above are from the construction of the original WALD system. Although the construction process for the replacement WALD will be different, these photos still illustrate the large scale of this type of project.