Experienced Team, Skilled Implementation Translates into Project Success
Location
Midwest
Industry
Utilities
Challenge
Close a wet fly ash impoundment safely and on schedule
Closing a 300-acre wet fly ash impoundment ─ especially one that requires dam modification and spillway construction ─ required a company with many capabilities. ENTACT tackled the challenge with expertise, coordinating a significant number of specialized activities during the project’s multi-year timeline.
Our in-house experience with dewatering, large-scale material management, cap construction, and water treatment enabled us to plan and execute this project in a safe and cost-effective manner.
ENTACT Solution
For this closure, ENTACT conducted a multi-year phased approach with a crew of more than 70 people. This large-scale project also included close coordination with nearby active utility plant operations.
Closure construction started with the draining of surface water via pumping or by digging temporary drainage channels in the deposited ash to direct water to an area immediately behind the main dam. As we managed the surface water, we also excavated the exposed fly ash and relocated and/or regraded the surface to meet subgrade elevations across the site.
Work progressed from the highest to lowest elevations across the impoundment to protect and manage storm water during construction. With close coordination of on-site activities, ENTACT completed the project safely and within the client’s timeline.
- Constructed several miles of access roads
- Drained surface water via pumping and/or temporary drainage channels
- Partially lowered the main dam and constructed new spillway
- Excavated the area of exposed fly ash
- Installed multiple drainage features including piping, culverts and cofferdams
The Results
- Safe management of more than 5 million cubic yards of ash, rock and soil
- Successfully closed the wet fly ash impoundment according to client and regulatory requirements
- Installed a 700 linear foot new spillway
- Constructed a more than 130-acre cap and containment system composed of geomembrane, geosynthetic materials and protective cover; seeded to establish vegetative cover
