Landfill Post-Closure Maintenance Program

LA Sanitation & Environment (LASAN) maintains and monitors five non-operational, closed municipal landfills across the City of Los Angeles. While landfills historically served as the primary solution for municipal solid waste, our focus today is on long-term post-closure environmental care, land restoration, and sustainable resource recovery.  

By carefully managing buried waste cells with protective bottom liners, thick soil caps, and active ventilation systems, we isolate old waste from rain, air, and surrounding soils. This ongoing work keeps neighborhood air clean, protects underground drinking water supplies, and turns former disposal grounds into valuable green spaces for Angelenos.  

California state law requires a post-closure monitoring period of at least 30 years after a landfill stops accepting waste. During this window, unsupervised public access is prohibited while LASAN environmental engineering teams measure ground settlement, manage stormwater drainage, and safely extract underground liquid (leachate) and methane gas.  

To ensure full compliance with regulatory standards set by the South Coast Air Quality Management District (SCAQMD) and the Los Angeles Regional Water Quality Control Board (LARWQCB), we operate environmental systems across our sites:  

• Landfill Gas Extraction: Vertical and horizontal wells connected to blowers, carbon scrubbers, and high-efficiency flares safely collect decomposing organic gas.  
• Moisture and Groundwater Tracking: Deep monitoring stations ensure rainwater does not penetrate the protective cover cap into buried waste layers.  
• Surface Care and Grading: Continuous landscaping, irrigation maintenance, and soil grading prevent surface erosion and maintain proper drainage.

Rather than flaring off methane gas generated by decomposing buried waste, LASAN converts waste gas into reusable electricity. At the closed Lopez Canyon Landfill in Lake View Terrace, an active collection network of 450 gas wells collects 3,400 cubic feet per minute of landfill gas.  

In 1999, LASAN constructed a 6-megawatt (MW) gas-to-energy power plant that supplies electricity to 4,500 homes. Expanding on this success, we partnered with the Los Angeles Department of Water and Power (LADWP) to add 50 microturbines—producing an additional 1.5 MW to power 1,500 more homes. This innovative energy recovery program reduces greenhouse gas emissions, generates municipal revenue, and earned national recognition from the Solid Waste Association of North America (SWANA). 

Once post-closure testing confirms that gas generation and soil movement have stabilized, LASAN collaborates with community partners to repurpose closed landfills into public parks and recreational facilities:  

Bishop Canyon (Elysian Park): Completed closure construction and transformed the 45-acre property into active recreational spaces, featuring athletic fields, picnic areas, children's play lots, and hiking trails.  

Gaffey Street (San Pedro): Converted the 30-acre site into a premier soccer field complex known as the "Field of Dreams".  

Lopez Canyon (Lake View Terrace / Sylmar): Home to the Lopez Canyon Environmental Center—where green waste is converted into free mulch for residents—and slated for future open-space public recreation once the 30-year monitoring window concludes.  

Sheldon-Arleta (Sun Valley): Site of the Cesar Chavez Recreational Complex, featuring soccer fields, a baseball diamond, a basketball court, and open play meadows.  

Toyon Canyon (Griffith Park): Completed monolithic cap closure in 2008 and currently undergoing post-closure maintenance to prepare the site for passive open meadow recreation.