Ground Improvement for Reclaimed Landfills-Paper

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The paper describes ground improvement for a 29-acre reclaimed municipal landfill in Elizabeth, New Jersey, redeveloped as a 481,650-square-foot warehouse with surrounding parking and truck-loading areas. The site contained heterogeneous municipal solid waste, compressible organic soils, and groundwater subject to tidal variation. A previous warehouse had experienced substantial settlement, and environmental restrictions made excavating and disposing of contaminated material costly.<br /><br />For the warehouse, the team used Controlled Modulus Column (CMC) rigid inclusions—grouted, auger-displacement elements—beneath spread footings and the slab. A compacted granular load-transfer platform distributes structural loads to the inclusions and underlying stiffer soils. Finite-element analyses were used to account for variable site grades and existing timber piles, and to design the system to meet settlement limits of 2 inches total and 0.5 inches differential between columns.<br /><br />Dynamic compaction (DC) was selected for the parking and loading areas. Because high-energy impacts could raise pore-water pressure or destabilize the working surface, the team conducted test areas with piezometers and heave-penetration tests. Results showed that the paved parking area could receive five drops per print in one pass, while the former pile-supported warehouse area required at least two passes. Careful sequencing controlled pore-pressure increases and limited heave.<br /><br />The combined methods provided economical support while reducing excavation, contaminated spoils, and construction delays. CMCs avoided the need for deeper piles and complex pile caps, while DC improved the surrounding ground and created capacity to reuse approximately 5,000 cubic yards of contaminated utility-excavation material on site beneath a cap, rather than paying to transport it elsewhere.

Keywords

ground improvement

controlled modulus columns

dynamic compaction

reclaimed landfill

settlement control

warehouse foundation

load-transfer platform

municipal solid waste

pore-water pressure

contaminated soil reuse