Mountaineer Bottom Ash Pond Closure and Repurposement
R. B. Jergens was contracted to close two 32-acre bottom ash ponds by removal and repurpose them with a synthetic liner system for waste water management. The clean closure project involved removing 375,330 cubic yards of bottom ash created over multiple decades and demolishing historical wooden structures and pipe inlets to remove the old discharge system. R.B. Jergens hauled the coarse grained bottom ash to the on site landfill at a rate the existing landfill management contractor was not prepared for. The inflow of materials from the pond closure as well as normal waste streams overwhelmed the crews and started to impact the placement of material. R.B. Jergens was able to offer our previous landfill management experience at the Mountaineer project as a value to the construction team and separate disposal areas were created within the landfill to be managed by each contractor. The willingness from the other contractor to share operational space and the client’s support to utilize our expertise allowed the project to ultimately be completed on time.
The original ponds were constructed out of spoils from an adjacent coal mine which proved to be difficult to manage near the bottom of waste. The materials would not dry using mechanical methods and became a complication within the landfill to navigate vehicles and achieve compaction requirements. R.B. Jergens proposed to utilize chemical stabilization using lime which reacts with the water molecules within the waste material to generate heat and steam the water out. Using 1,300 tons of lime, we were able to manage the landfill placement and meet production requirements.
Once all of the visual waste was removed, soils testing was required to confirm the ponds were cleaned within a threshold value and surveyed for certification reports. This led to the next project which was to import 200,233 cubic yards of clean soil from various places on site and compacted to develop new ponds that would support the power plant with waste water operations. The new ponds involved a 40’ x 21’ formed and poured concrete mix tank 20 feet below grade. R.B. Jergens phased the structural fill so we could construct the concrete structure at grade and then fill around it to design grades. This resulted in a safe and efficient sequencing and execution of work. The repurposed ponds were covered with 4 layers of synthetic liner materials and a 6,000 SF forebay pond was covered with a concrete lined revetment mat.
