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Home » News » Environment » Cause ‘unknown’ of landslide at Ontario County Landfill; no waste escaped facility, Casella says

Cause ‘unknown’ of landslide at Ontario County Landfill; no waste escaped facility, Casella says

  • / Updated:
  • Peter Mantius 

Casella Waste Systems Inc. has made “significant progress in moving soil over the weekend” at the Ontario County Landfill after a two-foot-thick layer of soil slid down the facility’s southwest face Wednesday afternoon, a company official said Sunday.

The landslide affected about three-and-half acres of a new seven-acre permanent cap that was being installed by contractors hired by Casella, County Administrator Chris DeBolt said in a press release. DeBolt said no one was injured, and the displaced “clean construction material” fell within the waste area of the county-owned landfill.

A subsidiary of the Vermont-based company operates the 389-acre facility located about five miles west of the Town of Geneva. It is the state’s third largest municipal waste landfill.

“There continues to be no impact to the surrounding environment and no injuries due to the incident,” Jeff Weld, Casella’s director of communications, said Sunday.

The company called the landslide “a veneer soil movement … on the cap membrane.”

Casella operates the Ontario County Landfill under a contract with the county, but it sometimes hires third-party contractors to complete construction work.

DeBolt told the Finger Lakes Times that the moving soil damaged some landfill gas collection equipment. “Because of this,” he said, “there is the potential for increased landfill gas odors in areas surrounding the landfill.”

The incident occurred within a few days of the one-year anniversary of the state’s announcement of a $500,000 fine imposed on the county and Casella for an assortment of environmental violations between the years 2015 and 2022.

The violations included 225 documented cases of excessive hydrogen sulfide in ambient air, failure to properly grade slopes, failure to install gas collection infrastructure and multiple releases of toxic leachate and contaminated stormwater. 


Required corrective actions were spelled out in a September 2022 state Department of Environmental Conservation consent order that applies to the county and the subsidiary, Casella Waste Services of Ontario, LLC.

Casella was responsible for paying the fine under its contract with the county.

DeBolt said Friday that county officials were working with Casella and the DEC to understand what happened. “At this time, the cause of the permanent cap failure is still unknown,” he said.

“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.”

The DEC publishes regulatory specifications for permanent cap design that are intended to provide redundancy to ensure that waste is not exposed to the outside environment.