Abstract:
Trenton Renewable LLC operates a food waste recycling and renewable energy production facility in Trenton, NJ. They have an anaerobic biodigester system consisting of 4 tanks and a high-efficiency cogeneration power plant. The tanks were put into service in 2019. It was noticed shortly after the tanks were filled that settlement was occurring. Trenton Biogas began regular survey monitoring and additional geotechnical investigation to track and explore the issue. At 3 years of operation there was up to 6.7-inches of differential settlement and 3 of the 4 tanks were out of tolerance for full operation. Nicholson was contracted to develop and design an underpinning system to stop the settlement and to relevel the tanks, while having as little impact to the plant production as possible. The final approach was to install micropiles to support the tank concrete slabs and utilize the micropiles as reactions to strategically lift the slabs back within tolerance of 1:200. This presentation will review the design approach, micropile underpinning, concrete slab jacking, and performance monitoring to successfully stop settlement and remediate the differential settlement of the tanks.