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Greenhouse Gas Emissions from S.D. Landfills Underestimated

KPBS News has learned the California Air Board has been under-estimating greenhouse gases from San Diego County landfills. Landfills create methane gas – 21 times more potent as a greenhouse gas than carbon dioxide. Joanne Faryon has more.

San Diego County’s three largest landfills have a system to capture dangerous gasses like methane that are generated from buried garbage. But according to the California Air Board, even the best systems can’t get all the gas – 25 per cent escapes into the atmosphere.

Hunsaker: Landfills of course, are part of the greenhouse gas emissions.

Larry Hunsaker is an engineer with the California Air Board. He calculates landfill emissions. But  Hunsaker says they’re only estimates based on how much garbage is in the landfill.


Organics in the landfill decompose over time and create greenhouse gases. The California Air Board says 25 percent of those gases escape into the atmosphere . Photo Illustration: David Streib/KPBS

When we asked Hunsaker to calculate actual emissions, based on gas capture rates KPBS obtained from county landfill operators, the real emissions were much higher than the estimates. Twice as high in some cases.

The Miramar Landfill , operated by the city of San Diego, was emitting 50 percent more greenhouse gas than estimated by the state.

Both Otay Landfill in Chula Vista, and Sycamore Landfill in Santee, are now emitting twice the amount of greenhouse gas then their 2005 estimate. Both are owned and operated by Allied Waste Industries.

Hunsaker says the estimates are a few years old, which may account for some increase, but its’ likely climate and the type of garbage in our landfills that accounts for the rest.

Hunsaker: Some landfills may have more organics than others. On average, the state as a whole, we have that number. But we don’t have it for any individual landfill. So I would expect to see some differences and it depends on whether the landfills in San Diego have more organics than average.

Organics are food and green yard waste, even paper. In San Diego County, Otay and Sycamore landfills bury thousands of tons of green waste every day. The green waste is ground up and used to cover other garbage. The state considers it an acceptable recycling practice. Miramar Landfill uses a negligible amount of green waste to cover garbage.

For KPBS, I’m Joanne Faryon.

Fugitive Gas Emissions as Estimated by the California Air Board in 2005
(Emissions are measured in carbon dioxide equivalent)


chart showing gas emissions

  • Miramar Landfill "Actual" is based on gas collection figures supplied by the City of San Diego for 2005.
  • Otay Landfill "Actual" is based on gas collection figures supplied by Allied Waste Industries in 2008
  • Sycamore Landfill: "Actual" is based on gas collection figures supplied by Allied Waste Industries in 2008.


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