A decade ago, Spokane was stuck with thousands of tons of unwanted compost that killed tomato plants.
It was a mixture, city officials said at the time, that forced the end of the city-run Spokane Regional Solid Waste System’s composting operation in Colbert.
The problem was a weed killer called clopyralid manufactured by Dow AgroSciences that was popular in Spokane. But unlike most herbicides, it didn’t break down quickly in composting.
The city said it suffered $4 million in damages and joined a class-action lawsuit with other composting operations against Dow.
Last month, city officials acknowledged that they settled the city’s portion of the suit in a confidential settlement with Dow finalized in March 2011.
Dow gave the city $23,000, but other details of the settlement have not been released.
The deal was kept so quiet that Russ Menke, the director of the Spokane Regional Solid Waste System, said Wednesday that he wasn’t aware the case had been finalized.
Damon Taam, the system’s contract manager, was heavily involved in dealing with the unwanted compost. He said the site, which is across the street from the North County Transfer Station, was purchased specifically for composting. The city’s claimed damages included the regional system’s costs to buy and improve the property as well as haul off the unwanted compost.
“There were quite a few communities who were harmed,” Taam said. “By far, we were probably the most damaged.”
Taam, who also was unaware that the case had been settled, said Eastern Washington at the time the problem emerged was one of the largest markets for clopyralid.
Dow AgroSciences spokesman Garry Hamlin declined to comment on the settlement. Indianapolis-based Dow AgroSciences is owned by Dow Chemical Co.
“Any agreement of that sort would be a confidential matter between participants, and we would not be in a position to discuss it with you,” he wrote in an email.
He added, however, that after problems emerged in compost operations, Dow petitioned the Environmental Protection Agency to disallow clopyralid’s use on residential lawns. Clopyralid is an active ingredient in Dow’s herbicide Confront.
Craig Cogger, a soil scientist at Washington State University’s Puyallup Research and Extension Center, said clopyralid was popular because it is active at low concentrations and its toxicity to mammals is insignificant.
He said the chemical hasn’t caused composting problems in the state in recent years.
It’s still allowed on golf courses and for some agricultural uses.
“The issue has largely died out, but there is always the risk of a stray load of manure that could be contaminated,” Cogger said. That’s because if straw is contaminated and eaten by cattle, clopyralid also is slow to break down in manure.
Clopyralid eventually breaks down in the soil. Tests by WSU showed that crops were significantly affected by contaminated compost the first year it was used. But crops planted in the same soil the next year didn’t appear to be affected, Cogger said.
After the problem emerged, Spokane sold the bad compost to an Oregon dairy operation. It shipped its green waste to Oregon and then to Royal City, Wash., for several years until it agreed to contract with a new Lincoln County operation, Barr-Tech, last year. Officials say they regularly test the city’s compost for the chemical.
Meanwhile, the last pile of problem compost recently disappeared. The city kept a pile of it on property near the Waste-to-Energy Plant in case it was needed for tests in the suit, Taam said.
It was either hauled away or used in landscaping on the site, where Waste Management is building a municipal recycling facility.