Lessons Learned from Landfill Construction Inside Former Ash Basins

John Bove, AECOM

Description

Lessons Learned from Landfill Construction Inside Former Ash Ponds Authors Mr. John Bove - United States - AECOM Abstract Lessons Learned from Landfill Construction Inside Former Ash Ponds John Bove1 1AECOM, 6000 Fairview Road, Suite 200, Charlotte NC 28210 KEYWORDS: Landfill, Ash Pond ABSTRACT Former ash pond sites can be good candidates for siting engineered landfills to place excavated ash from closure by removal sites and future production ash from power plants. For closure in place ash will need to be excavated within an area before building a landfill. These sites offer cost advantages over greenfield landfills such as hauling distance, shared infrastructure, logistics, footprint reduction, and environmental benefits. However, several technical challenges need to be addressed at the design and permitting stages to result in successful project outcomes. Several landfills designed inside former ash ponds are under construction or in early stages of operation. These projects have highlighted several challenges and lessons learned related to: 1. timing of site investigations (prior to or after ash excavation); 2. establishing seasonal high ground water table for design (prior to dewatering vs after dewatering; measurements versus modeling; transient impacts vs long term conditions); 3. location of the landfill footprint inside the ash basin (high ground, ash thickness, strategy for steam beds etc.); 4. use of underdrains during design phase versus needing to design during construction phase; 5. subgrade preparation challenges (undercuts, unintended ground water level changes due to stone bridge lifts, proof rolling challenges and use of lime stabilization); 6. challenges in using existing dams as perimeter berm buttresses; 7. surface water management and associated groundwater level influences; and 8. several other challenges. This presentation will provide an overview of the above challenges. Construction phase photographs will be used to illustrate practical considerations.

 
May 15th, 10:30 AM May 15th, 11:00 AM

Lessons Learned from Landfill Construction Inside Former Ash Basins

Grand Rapids, Michigan

Lessons Learned from Landfill Construction Inside Former Ash Ponds Authors Mr. John Bove - United States - AECOM Abstract Lessons Learned from Landfill Construction Inside Former Ash Ponds John Bove1 1AECOM, 6000 Fairview Road, Suite 200, Charlotte NC 28210 KEYWORDS: Landfill, Ash Pond ABSTRACT Former ash pond sites can be good candidates for siting engineered landfills to place excavated ash from closure by removal sites and future production ash from power plants. For closure in place ash will need to be excavated within an area before building a landfill. These sites offer cost advantages over greenfield landfills such as hauling distance, shared infrastructure, logistics, footprint reduction, and environmental benefits. However, several technical challenges need to be addressed at the design and permitting stages to result in successful project outcomes. Several landfills designed inside former ash ponds are under construction or in early stages of operation. These projects have highlighted several challenges and lessons learned related to: 1. timing of site investigations (prior to or after ash excavation); 2. establishing seasonal high ground water table for design (prior to dewatering vs after dewatering; measurements versus modeling; transient impacts vs long term conditions); 3. location of the landfill footprint inside the ash basin (high ground, ash thickness, strategy for steam beds etc.); 4. use of underdrains during design phase versus needing to design during construction phase; 5. subgrade preparation challenges (undercuts, unintended ground water level changes due to stone bridge lifts, proof rolling challenges and use of lime stabilization); 6. challenges in using existing dams as perimeter berm buttresses; 7. surface water management and associated groundwater level influences; and 8. several other challenges. This presentation will provide an overview of the above challenges. Construction phase photographs will be used to illustrate practical considerations.