The South Coast Botanic Garden lies atop a portion of the Palos Verdes Landfill. From 1952 to 1965, household refuse or “trash” was placed in the excavated areas on the site and the landfill was built up to the current ground level. Upon its closure, a cap of soil was placed on top of the refuse, and the Botanic Garden was started.
As the refuse in the landfill decomposes, methane gas is generated. The County of Los Angeles Sanitation District has maintained a methane gas collection system since the early 1980’s in order to capture the methane and dispose of it properly. Technicians monitor the landfill cover quarterly, searching for areas where methane gas may be escaping through the cover soil. When areas are found that need cover soil repair, the cover soil is reworked or additional cover soil is added. Rarely, site gardeners will notice areas where methane may be escaping through the cover, either by smelling landfill gas or by noticing areas where a plant is dying. Botanic Garden staff then notifies the Sanitation District operators so that necessary cover repairs can be made in a timely fashion.
As you tour the garden, notice the bowl-like topography of the site. The site was a mine before it was filled with refuse and topped with a garden.