San Luis Obispo County air pollution officials are investigating the foul rotten-egg odor that has been coming from Firestone Walker Brewing Co. in Paso Robles since last month — a smell that has prompted dozens of complaints from residents and businesses and more than $1 million in anticipated fixes for the brewery.
Officials with the San Luis Obispo County Air Pollution Control District say they are monitoring the levels of hydrogen sulfide gas wafting from the brewery’s wastewater ponds and have found that the amounts are not harmful to health. The amounts can cause headaches, nausea and irritability, however, according to state officials.
On March 31, the Air Pollution Control District issued a notice of violation against the brewery because it had received 30 public complaints, which is above its threshold for defining a nuisance.
And, though fixes are ongoing, there’s no firm timeline for when the stench will be gone.
Digital Access for only $0.99
For the most comprehensive local coverage, subscribe today.
Firestone Walker installed the two wastewater ponds on its campus off Ramada Drive earlier this year to treat the rinse water from its beer-making tanks. The ponds — filled with water that included organic matter such as yeast and grain — haven’t been working correctly, and unseasonably warm weather caused the foul odor to spread over many parts of town and into northern Templeton.
Severity of the odor has varied, depending on weather and wind conditions, officials said.
Resident Robert Raynolds said the smell made him physically ill on Monday. He lives on the east side of Paso Robles several miles north of the Firestone site.
“The smell has come and gone in the last couple of weeks, but Monday was the worst it’s ever been,” he said. “And it was just a blast of it, and it just really put me in a foul mood.”
Raynolds was working outside when the smell hit Monday morning, and by afternoon, he and his wife were forced to stay inside and shut all their windows and doors. By dinnertime, he said he didn’t even want to cook because he was so disgusted.
“I just became irritable. I became a little nauseous — just a sick-to-my-stomach kind of feeling,” he said.
Safe but irritating smell
The air pollution district opened a case with the brewery last month and was working this week to monitor hydrogen sulfide levels in the air and oversee management of the stench. Once the case closes, Firestone could be subject to fines.
The district measured the amount of the gas at different locations in the city during the morning, afternoon and night “to get a profile of how the odors are impacting the community,” district planning manager Aeron Arlin-Genet said.
The measurements also create a baseline to determine how well Firestone’s fixes are progressing.
At the south end of town, the district on Wednesday measured hourly averages of hydrogen sulfide at 0.03 parts per million at the south end of Ramada Drive and at Cuerno Largo Way directly across from Firestone on the opposite side of Highway 101.
The California Environmental Protection Agency Air Resources Board deems hourly averages of 0.03 parts per million to be low enough to protect public health, including children, the elderly and people with chronic illness like asthma.
However, if people can smell the gas, they can experience negative side effects from it, said Dr. Alvaro Alvarado, air resources supervisor.
“Some people will detect the odor at much lower levels at 0.03, while others won’t smell it at all,” Alvarado said.
Some of those low-level effects include headache, nausea and irritability. At higher concentrations, the gas is considered an “irritant,” producing symptoms such as eye irritation, cough and sore throat, he said.
“Higher concentrations typically average between 2.5 and 5 parts per million, though it will be different for everybody,” he said. However, when the smell goes away, so do the symptoms, Alvarado said.
“In general, this is a reversible type of effect,” he added.
Complaints to the air pollution control district have ranged from people who said the smell made them annoyed, nauseous, unable to sleep, unable to work outside or open their doors and that the smell stuck to their drapes and furniture, Arlin-Genet said.
On Thursday, brewery co-founder Adam Firestone said the odor and treatment systems have improved, but the process is working too slowly.
“And that means that while the smell has lessened, it's still unacceptable,” he said.
One measurement that wastewater treatment systems use to determine if they’re functioning properly is tracking the amount of organic material per liter of water. At Firestone’s ponds, that measurement has been reduced by 85 percent since the problems arose in March. His engineers say the ponds need to drop another 10 percent to function properly for the smell to dissipate.
Firestone said the brewery has spent “over $1 million and counting” to help correct the malfunctioning ponds, including trucking new waste to an undisclosed city facility outside San Luis Obispo County, buying portable wastewater treatment plants that arrived on multiple trailers to tie into the existing plumbing and help further the treatment process, adding liquid oxygen to the ponds and doubling the aeration of the water.
The brewery has also been using vineyard frost fans to circulate air and blow it away from neighbors, Firestone said. “It's helped, but not without some problems.”
One neighbor said the fans are too noisy.
Firestone built the ponds after state and federal regulators told the city the brewery's tank-rinse water needed to be treated separately from the city's wastewater system.