The $375,000 study was conducted last year by the clean air agency using electronic odor monitors and the observations of 11 volunteers. It was aimed at determining the source or sources of offensive odors in the Snohomish River Delta.
Results of the study, released Jan. 23, showed mixed results.
The volunteers and the monitors differed in their impressions. The volunteers, who live in Marysville and north Everett, reported smelling compost or fresh waste far more than any other odors. Electronic monitors, or “e-noses,” reported strong smells coming from the Everett and Marysville wastewater treatment plants, as well as from Cedar Grove.
The e-noses were placed at Cedar Grove, the Everett and Lake Stevens wastewater treatment plants and the Cemex plant in north Everett. The monitors were purchased from Odotech of Montreal, Canada.
A monitor was not placed at the Marysville sewage plant because city officials there opposed the study, and did not give permission. Data for that location was generated by a computer model, including weather information, officials said.
In a letter dated Jan. 26, Cedar Grove attorneys cited previous news stories in which agency officials openly discussed aspects of the study they believed to be contradictory or inconclusive.
“The agency must immediately cease and desist making statements unsupported by the scientific evidence in the odor project that are harmful to Cedar Grove,” Seattle attorney Michael E. Patterson wrote. “If the agency refuses to do so, Cedar Grove will consider its legal options.”
Clean air agency officials seemed unfazed by the letter at a public meeting in Everett on Thursday. They discussed the study candidly with about 15 people who attended.
On Friday, agency Director Craig Kenworthy sent a letter to Cedar Grove’s law firm, Patterson Buchanan Fobes & Leitch, in response.
“Our agency disagrees with the assertions in your letter regarding our opinions on the Community Odor Monitoring Project,” Kenworthy wrote.
He went on to say that the agency plans to continue to comb the data for insight and hopes to meet with Cedar Grove, Everett and Marysville.
The study is just one step in trying to determine the source or sources causing the stench, he said.
Two parts of the study need to be examined further.
First, there’s no explanation for the discrepancy between the human observers’ data and the electronic data.
Second, more work needs to be done to determine how odors can spread in calm atmospheric conditions, said Steve Van Slyke, compliance manager for the clean air agency.
Computer modeling before the study was based partly on average wind conditions, and the study year — October 2012 to November 2013 — was considerably calmer than normal.
That makes the data harder to interpret, officials said.
While the information is useful, the technology has limitations, agency officials said.
“It can do part of what the human nose can do, and there are things it can’t do,” Van Slyke said. “The e-nose can’t tell you if what is smelled is unpleasant or not. That’s a human response.”
In Patterson’s letter, he said statements by the Clean Air Agency “repeatedly disregard Odowatch results without providing a sound foundation for the determination to do so.
For example, Patterson wrote, “the agency summary states that Odowatch ‘cannot establish the actual odor concentration of any offsite location at any specific time.’”
He added, “There is little doubt that a scientific, tested, and proven system, such as Odowatch, has greater reliability than completely subjective methods of analysis — such as using the human nose.”
Patterson went on to say that nearly 80 percent of the odor observations were made by three of the 11 volunteers.
And two volunteers were involved in class-action lawsuits pending against Cedar Grove. A third has called in numerous odor complaints, Patterson wrote.
Before the study, Cedar Grove agreed to the use of volunteers in addition to the e-noses.
Marysville city administrator Gloria Hirashima said the results validate the city’s position from the beginning — that the study was a waste of time and money. The source of the stink is Cedar Grove, she said.
“In some ways the study tried to complicate an issue that the odor observers could tell you is relatively straightforward,” she said.
“Because of the weather conditions, which cannot be controlled, it made the modeling unreliable. At our site, it was all modeling.”
Cedar Grove put $200,000 into the study, with Seattle, King County and the clean air agency pitching in the rest. Cedar Grove, which also has a location in Maple Valley in King County, collects yard and food waste from haulers in Snohomish and King counties and turns it into compost that it sells for use in gardens.
In 2011, Cedar Grove was fined $119,000 for odor violations. That amount was applied to the company’s share of the odor study.
The city of Seattle and King County pitched in $100,000 and $50,000, respectively. The Clean Air Agency is spending $25,000.
Bill Sheets: 425-339-3439; email@example.com.
The Puget Sound Clean Air Agency’s odor study is available online at tinyurl.com/mmd3yon.
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