Modesto's 30-acre compost site is caught between a green rock and an eco-friendly hard place.
It takes 65,000 tons of green waste each year and turns it into organic fertilizer, a key component in helping the city comply with a state mandate to divert half of its garbage out of landfills.
But a proposed rule aimed at reducing ozone pollution could drive up the cost of composting, which could lead to cutbacks at the site and more waste winding up at landfills.
The San Joaquin Valley Air Pollution Control District wants to rein in volatile organic compounds, a precursor to smog that leaks out of the seemingly endless rows of decomposing material that sit at large compost sites.
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Its proposed rule would require companies and cities that compost more than 50,000 tons of waste a year to install equipment that filters smog contributors. The district's board of directors is expected to vote on the rule early next year.
Putting in the filtering equipment would oblige Modesto to more than double what it charges to accept a ton of green waste from $18.75 to $40, estimated Jocelyn Reed, city solid waste division manager. Or, she said, the city could scale down its operation to fit in under the 50,000-ton threshold.
Increased composting costs would start to make the landfill attractive, composters say. The county landfill charges $30 to take a ton of garbage.
"It's going to be twice as expensive to compost material as it is to put it in the landfill because of the demands of what they expect you to do," said Dennis Shuler, environmental affairs director for Modesto's Gilton Solid Waste Management, whose company composts 30,000 to 40,000 tons of green waste a year.
On the finished end, some industry representatives worry that more expensive compost could drive more farmers to buy synthetic fertilizers. The city charges $15.75 for about 1,200 pounds of compost.
"Rather than beneficially reusing these materials through compost, because of the added regulatory burden and cost, it would go back to landfill or be disposed of in the least environmentally friendly way," said Jan Marie Ennenga, executive director of the Manufacturers Council of the Central Valley.
The air district is taking those criticisms into account while it refines its proposal, said George Heinen, the air district's supervisor for rule development.
Every little bit counts
He said the air district must consider any source to reduce the valley's chronic pollution. Compost sites could contribute as much as 57 tons of volatile organic compounds to the valley's air each year, according to the district's early estimates.
"It all adds up; we need every tenth of a ton," Heinen said.
Those numbers are a source of disagreement between the air district and industry.
The air district based its projection on a Southern California study that showed a ton of compost material yields 3.84 pounds of volatile organic compounds.
A 2007 study at Modesto's site conducted by the state Integrated Waste Management Board came up with much lower numbers -- from 0.8 pounds per ton of pure green waste and as much as 2.6 pounds per ton of composted food waste.
"At this point, we do believe there's quite a bit, but the exact number is still being refined," Heinen said.
Matt Cotton, a composting consultant, said the industry he represents thinks of itself as green because of its work diverting waste from landfills.
"Clearly, the idea of regulating emission from green waste composting is very brand new, and you have the juxtaposition of these competing goals, which are both desirable," he said.
Bee staff writer Adam Ashton can be reached at email@example.com or 578-2366.