LOS ANGELES (AP) — The largest dump in Los Angeles County is under fire from several agencies for a stench that some residents say is unbearable.

About a dozen witnesses testified Saturday at a South Coast Air Quality Management District hearing to consider a nuisance-abatement order against the owner of Sunshine Canyon Landfill

Residents who live near the Sylmar dump in the San Fernando Valley have complained of headaches, nosebleeds and respiratory problems and say they shut their windows and don’t spend time outdoors.

“It’s horrible. We’ve become prisoners in our own house,” said Ellie Kotoyan, who testified that her 16-year-old son lost five weeks of school the past two years because of headaches she blamed on the dump. “I just don’t want to have the smell. I don’t want to have the nuisance. I want it stopped.”

More than 3,000 complaints have been filed with the South Coast Air Quality Management District since 2013 for morning and evening odors from the dump.

The proposed abatement order would eliminate a third of the garbage that could be dumped, trim morning operations by three hours and require better covers to control gases from decomposing garbage.

The owner of the landfill, Republic Services, has spent $27 million to control methane, others gases and odors, and the abatement order will not improve the smell, the company’s lawyer said.

“It’ll have absolutely no impact on landfill odors, because the waste in the landfill generates gas for decades,” attorney Thomas M. Bruen said. “The only way to control odor is to have a good gas-collection system, which we believe we have.”

The company said most of the complaints come from fewer than 20 residents.

In addition to a possible crackdown by the air district, the Department of Public Health issued violation notice last week to the company.

Los Angeles Councilman Mitch Englander has introduced a motion to get the city to find another location for its trash.