The New York State Department of Environmental Conservation and Casella Waste Management of Ontario LLC are investigating an incident that occurred at the Ontario County landfill in the town of Seneca. According to County Administrator Chris DeBolt, approximately 3.5 acres of a newly constructed seven-acre permanent cap slid down the southwest face of the landfill late Wednesday afternoon. DeBolt said no injuries were reported and the displaced clean construction material remains within the waste area of the landfill and has not impacted surrounding areas.
Throughout the summer construction season, Casella, which operates the landfill under an Operations Management and Lease Agreement with the county, was placing permanent capping material on an approximately seven-acre section of the landfill. This work was carried out by third-party contractors and engineers retained by Casella in accordance with DEC-approved plans and regulatory requirements.
Ontario County officials have been working closely with Casella and the DEC since the incident occurred to understand what happened and how best to mitigate any potential impacts to the surrounding community or the environment. At this time, the cause of the permanent cap failure is still unknown. Extensive independent testing is being conducted by all parties involved to understand the cause of the failure and develop remedial action plans.
During the failure of the permanent cap material, a large volume of soil migrated down the slope of the landfill face on the Southwest section of the site. This moving soil damaged some landfill gas collection infrastructure in the affected area. Because of this, there is the potential for increased landfill gas odors in the areas surrounding the landfill.
Due to the safety concerns remaining at the site, the assessment of damages is ongoing. The DEC regulatory specifications for permanent cap design are developed to provide redundancy, ensure isolation of the waste mass, and protect the surrounding environment. At this time, it appears that while the permanent capping soil was displaced and that some damage was sustained by the synthetic waste barrier, it does not appear that any waste material was exposed, compromised, or migrated outside the confines of the landfill. This incident occurred in a portion of the landfill that was not actively accepting waste and therefore has no impact on waste acceptance operations.
Staff from Ontario County, Casella, DEC, and the involved contractors continue working to ascertain the cause of this failure and develop a safe and expeditious remedial action plan.
