Austin will expand its curbside composting to 53,000 more households this fall, bringing composting to three-quarters of the city.

Composting collection for those homes will begin the week of Sept. 23, according to the city's waste management branch, Austin Resource Recovery. Currently, 95,000 homes receive the service.

Austin Resource Recovery plans to have composting collection extended to all city homeowners by 2020, if City Council members approve funding for it. It cost $6.4 million this fiscal year and replaced collection of yard trimmings. A $1 monthly fee on all resident utility bills funds it.

A spokeswoman for the department said it's unclear what the cost expansion being requested for the next fiscal year will be.

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Curbside composting in Austin began as a test run in a few neighborhoods in 2013, before expanding to more than 50,000 residences in 2017. The program involves wheeling out carts to households specifically for organic materials ranging from rotten food and old pizza boxes to yard trimmings.

City employees said the program can help Austin make progress on its goal of diverting 90 percent of materials from landfills by 2040. They cited a study saying almost half of material homes send to landfills could be composted.

"Since the program began, ARR has collected almost 100 million pounds of compostable material," said Richard McHale, Austin Resource Recovery's interim director. "As we expand this program to more customers, we keep more compostable material out of area landfills, and make larger strides toward achieving Austin's Zero Waste Goal."

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Composting could benefit customers if they are able to reduce their waste enough to downsize to a smaller trash cart.

Critics have questioned whether enough people will commit to composting to make the program worth it.

About 30 percent of residents have used the compost bins provided, according to a city study from March 25 to May 16. A compost audit in August found a contamination rate of 2.5%.

"We would like to see more participation but we have been pleasantly surprised— enthusiastic — that we've seen very low contamination," department spokeswoman Memi Cárdenas said.

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