West Marin Compost has canceled the final free green waste day of the summer due to an overwhelming response, and the company is looking for ways to increase composting capacity so it can keep serving those who are clearing defensible space around their homes. The first three green waste days saw cars and trucks backed up on Nicasio Valley Road to the point that traffic control was needed. The facility approached its capacity of 12,500 cubic yards, and the July 25 date was canceled. General manager Will Bakx attributed the heavy traffic to more advertising, greater fire safety awareness and a larger number of people staying home and doing yard work these days. A few of the people accessing the site were not from the area or landscapers who stockpiled waste, owner Nancy Lunny said. “In a way, it’s great, but on the flipside, we have a limited amount of room,” she said. “We really love being able to do this for the public, so we’re trying to revisit it based on this response.” Moving forward, the company is looking at upgrading its composting system. Currently, workers use a windrow turner machine, which turns compost 10 to 15 times before it is ready to use. But leadership is looking at switching to a new system: covered aerated static pile composting, which only requires one turn, during which the compost goes from an active state to curing. With a layer of finished compost on top, the system pumps air through heat-resistant pipes that run through still waste, slowly turning it to compost. It uses less energy and reduces emissions. “It’s really quite an amazing system,” Mr. Bakx said. By turning waste into mulch or compost, both systems support carbon farming: With a layer of compost or mulch on top, plants’ ability to sequester carbon increases. Mr. Bakx is hopeful that West Marin Compost can purchase the new system by the end of the year. Battalion chief Christie Neill, who oversees the vegetation management program for the Marin County Fire Department, said she is encouraged by the demand for free green waste disposal, but that it’s time to update the program. In March, voters approved a tax of 11 cents per building square foot to fund the Marin Wildfire Prevention Authority, a countywide agency dedicated to fire safety. The tax will raise about $20 million per year when it takes effect in January, and a majority of the funding will go to vegetation management and defensible space inspections. So, more green waste days are coming. Ms. Neill said the fire department is considering a voucher program, in which inspectors give homeowners the go-ahead to take their green waste to West Marin Compost. The fire department and other partners are also looking at grants so West Marin Compost can expand its capacity. The free green waste days are funded by an annual $10,000 grant from Marin County, which covers some but not all of the facility’s costs.