Cambridge compost returns to the city on Saturday for a giveaway in honor of Earth Day. (Photo: Cambridge Department of Public Works)

Earth Day’s not until April 22, but Cambridge celebrates Mother Terra on Saturday at the Main Library campus with plenty of sustainability offerings and events, namely a compost giveaway – 20 tons of composted yard waste such as leaves, cut grass and twigs that residents can use as mulch and soil enrichment. Folks from the Forestry Department and the Cambridge Garden Club will be on hand to answer questions about plants and trees, and so will the city’s stormwater program manager to discuss a storm steward volunteer program in which residents sign up to help keep contaminants out of rivers.

Inside the library will be a Fix It Clinic, with a crew of MacGyvers helping repair that broken something sitting around the house that you’ve been thinking about tossing. “We would love for people to try to fix broken items and put them back into use, as it reduces waste,” said Michael Orr, the city’s director of recycling.

The Earth Day Celebration takes place from 9 a.m. to 1 p.m. (with a Sunday rain date) at Joan Lorentz Park at 441 Broadway, Mid-Cambridge, in front of the Cambridge Main Library; the clinic is 11 a.m. – 2 p.m. at The Hive inside the library.

Attendees at the Saturday Earth Day Celebration need to register for the Fix It Clinic. The organic compost giveaway requires participants to bring their own bins or containers for up to 20 gallons of material.

Given climate change, dwindling resources and space, the city takes recycling and waste reduction seriously. It set goals in 2008 to reduce then-current trash levels in half by 2030 and by 80 percent by 2050. The 2019 version of the Zero Waste Plan called for a 30 percent reduction by 2020, which meant household trash volumes had to shrink to 15.9 pounds per household per week from 22.8 pounds, the 2008 benchmark. In 2019, that mark was 16.4 pounds; Orr was happy to report this week that they are at 14.8 pounds.

Still, the city has much to do to meet the 2030 goal.

Much of the success Orr noted is from an expansion of a curbside composting program, which puts food waste in compostable bags to be turned into high-energy fertilizer pellets, in place at small and medium-size residential building up to large complexes of as many as 400 units. Commercial properties are part of the composting program as well. The program is not mandatory, but “encouraged,” Orr said. But composting program participants may note how light landfill trash bags become compared with their 3-gallon biodegradable bags, which get packed densely with food waste and paper towels.

The city makes curbside and in-unit bins available free and gives away the biodegradable bags as well at the offices of the Department of Public Works at 147 Hampshire St., in the Wellington-Harrington neighborhood. A Get Rid of it Right app and website is updated with changes over time in how and what gets recycled or disposed of, Orr said.

The 2020 goal was never truly realized because Covid pandemic lockdowns halted the curbside composing program; all food waste was directed to landfill for several months. Orr said that after a five-year run, the city is updating its Zero Waste Plan to better align with the 2030 and 2050 goals.

Another factor in progress toward 2030 goals was the banning of mattresses and textiles from trash, Orr said. Textiles such as shirts can be recycled or donated; mattresses, which can be picked up curbside by the city upon request, are taken apart for composting or recycling. Approximately 70 percent to 80 percent of mattress and box spring components can be recycled.