DCO Energy, LLC (DCO), was the design-build contractor for the $200M, 50 MW AGE Biomass Renewable Energy Plant in Albany, Georgia, a project jointly developed by Constellation Energy (Exelon) and Proctor and Gamble Co., Inc. The original foundation design by a local consultant had resulted in a very conservative working pile resistance and a significant number of costly battered piles. Therefore, new steel H-pile foundations were proposed.
Geosyntec’s Scope of Services
Geosyntec provided foundation engineering services to value-engineer the pile foundations of the AGE Biomass Plant and improve their efficiency both in terms of cost and construction schedule. We accomplished both project objectives by implementing our experience in deep foundation pre-design testing programs and complex Coastal Plain geology to increase the working geotechnical resistance of the piles from 70 tons to 110 tons, reducing the total number of piles for the project by nearly 40%. Geosyntec developed a field testing program comprising dynamically monitored test piles for prediction of axial compression resistance at the end of initial drive and at 7-day restrikes, lateral load tests, and tension load tests. One of the most significant accomplishments of the testing program was the demonstration that the H-piles had greater than expected lateral resistance at tolerable deformations, allowing Geosyntec to eliminate the need to drive battered piles and improving pile installation production rates. Geosyntec developed the pile foundation specification for the project and established and adapted the driving criteria throughout production installation to maintain the design and performance intent.
Difficult ground conditions, in the form of highly irregular, weathered fossiliferous limestones manifested themselves during installation of piles for the vital turbine structure and led to significantly increased pile lengths, from typical lengths of approximately 80 ft to upwards of 120 to 142 ft. The severity of these conditions was not observed during the Cone Penetration and microgravity geophysical testing conducted at the site prior to completion of the foundation design. Geosyntec evaluated these critical piles separately and developed site-specific soil setup factors using a large number of dynamic monitoring results from initial drives and restrikes to establish that sufficient long-term geotechnical resistance was available.
Even with the subsurface conditions and installation challenges, Geosyntec’s experience in deep foundation engineering and construction resulted in substantial cost savings and reduced the foundation construction schedule by 3 weeks.
- Location: Albany, Georgia
- Client: DCO Energy, LLC
- Project Practice Areas: Environmental Management, Geotechnical
- Type of Facility: Power Plants
- Services Provided: Geotechnical and Construction Engineering, Value Engineering of Driven Pile Foundations, Dynamic Pile Monitoring, Static Pile Load Testing, Construction Engineering
- Type of Work: Geotechnical and Construction Engineering
- Governing Regulation: State and local