Title
Accept report regarding management and mitigation at the San Ardo Landfill.
Report
RECOMMENDATION:
It is recommended that the Board of Supervisors accept report regarding management and mitigation at the San Ardo Landfill.
SUMMARY/DISCUSSION:
The San Ardo closed landfill is a former Class III landfill located near the intersection of Cattleman Road and U.S. Highway 101. Solid waste disposal operations were conducted at the site between 1980 and 1984, at which time filling operations were curtailed and the landfill was capped with a soil landfill cap and closed. Landfill capping is a containment technology that forms a barrier between the solid waste and the surface, thereby shielding humans and the environment from harmful effects of the solid waste and limiting the migration of both landfill gas and contamination originating from the solid waste.
Currently, the landfill is being used exclusively as a refuse transfer station. Refuse operations are managed by King City Disposal Company, a subsidiary of Waste Management, Inc., which has an exclusive unified franchise agreement with the County. The transfer station is open to the local public on Saturdays and closed the rest of the week.
A deformation in the cap was observed in November 2009 near the center of the landfill. At that time, the area was approximately 23 feet by 14 feet in size. A five (5) foot deep void was observed in the west end of the depressed area and a smaller, 18-inch-deep void was observed at the southeast corner of the distressed area. In December 2009, the depressed area was repaired
by excavating soils in the area, replacing and recompacting.
During the 2013-14 rainy season, a geologist from the consulting engineering firm that provides inspection, monitoring and reporting services, observed the cap subsiding in several locations across the landfill. Continual subsidence and the creation of a sinkhole was apparent during the 2014-15 rainy season and a recommendation ...
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