The 145-acre "South Parcel" at OII Landfill is located on the south side of the 60 Freeway. This is the larger of two parcels used by OII as a regional landfill, which operated from 1948 to 1984.
The soil cover over the landfill area is approximately six feet thick, and is composed of soil with a vegetation layer on top. It is designed to look like a southern California hill while keeping landfill gas in and rainwater out. The seasonal greening and browning of the Landfill's vegetation is part of the intended design for the environmental cover, which prevents winter rains from entering and "wicks" internal moisture during the dry season.
The "top deck" of the OII Landfill has views of the surrounding communities and the Los Angeles basin. The Landfill settles approximately one foot per year, due to the decomposition of waste materials and the continual extraction of landfill liquid and gas.
Approximately 400 wells extract landfill gas and liquid from the landfill, conveying it to the treatment facilities on the north side of the 60 Freeway.
There are approximately 100 sampling wells, which monitor the effectiveness of groundwater cleanup measures beneath the Landfill. The groundwater at the site is not associated with potable or drinking water sources, but impacted groundwater cleanup is still a required component of the remediation. A combination of degradation and extraction processes are used for the remediation, and an extensive sampling regime also are part of the ongoing efforts.
Stormwater is collected in a series of concrete-lined channels around the South Parcel, and collected in an onsite detention basin.
summer, as part of the natural process to wick moisture out of the Landfill.