SANITARY LANDFILL SUPERFUND SITE CLOSURE

ENTACT was engaged to perform closure of a 100-acre former sanitary landfill that previously operated as a sand and gravel quarry. Over the site’s operational history, industrial and municipal wastes were deposited in the eastern portion of the site, while foundry sand and fly ash were placed in disposal areas across the western third. A public thoroughfare bisected the site, adding complexity to logistics and phasing.

ENTACT executed a comprehensive environmental remediation and geotechnical construction program to safely close the landfill, consolidate and manage waste, and restore the site to meet long-term regulatory and environmental performance objectives.

Scope of Work:

• Cleared, grubbed, and stripped topsoil across the work area
• Demolished existing structures, including concrete foundations and production water wells
• Excavated and consolidated 160,000 cubic yards of waste from one disposal area, an adjacent off-property area, and a city lot; backfilled and vegetated affected areas
• Graded and consolidated 160,000 cubic yards of waste across four disposal areas and installed 58,000 cubic yards of engineered subbase for cap construction
• Constructed three composite landfill caps using flexible membrane liner (FML), geosynthetic clay liner (GCL), and 250,000 cubic yards of soil and sand components
• Decommissioned 36 existing wells, including groundwater monitoring, leachate, and NAPL piezometers
• Installed new groundwater monitoring wells and perimeter landfill gas probes
• Installed a non-aqueous phase liquid (NAPL) recovery system and leachate management infrastructure
• Phased decommissioning of the existing landfill gas (LFG) collection and flare system, and installed a new LFG system
• Constructed a 9-acre stormwater basin, a 5-acre wetland, and permanent stormwater control features
• Restored the previously closed public roadway bisecting the site
• Completed seeding and vegetation of more than 100 acres, including lawn, bioswale, and mesic-prairie seed mixtures tailored to designated areas

In total, ENTACT managed more than 650,000 cubic yards of material, capped more than 75 acres, decommissioned 36 wells, and restored the full 100-acre site. This project delivered a sustainable closure solution and significantly enhanced environmental quality across the property.