How Portland Maine’s Compost Drop Offs Are Working

Portland, Maine has reduced its waste by over 60% and increased recycling sixfold since 1998 through aggressive diversion practices. But as the New England community pushes to go further, with a goal to reach zero waste by 2050, it’s found a missing link.

“We are proud of our progress in reducing our waste stream and recovering more for recycling, but through a waste composition study we did with the University of Maine, we realized we needed to do something to divert food waste. Thirty-six percent of what residents were throwing out by weight was food scraps and other organics,” says Troy Moon, Sustainability director for the City of Portland, Maine.

On Earth Day (April) in 2021 Portland launched five food scrap drop-off locations to target that stream, pulling from the solid waste budget to be able to offer this service free to residents, with their discards supplying an aerobic digestion operation at Maine’s second largest farm.

Located near city-owned gardens, the lined, covered 64-gallon carts are strategically set up so that most residents are within a mile or less of a drop-off location.

They can leave meat, cheese, bones, coffee grounds – basically any food scrap – though packaging is discouraged as it adds no value to the compost program.

“We decided to partner with the Parks department and place compost drop-offs near gardens they maintain because this provides a visual to better understand the closed loop connection whereby food is grown, eaten, and the remaining scraps can go back to growing more food,” Moon says.

The program has been well received. While the city started with two carts per drop off, demand has necessitated adding one to three more carts per site. Currently, Portland is collecting 14 to 15 tons a month in total from locations open 24/7.

Portland will soon add three more locations and is looking at supplementing through a local subscription-based curbside service provider for residents who want another option.  The goal is to get a flat rate (which could run about $18-$20 a month) to provide price stability and ideally to collaborate with the provider on community education and outreach explaining the benefits of diverting food scraps.

“If we can promote food waste by every means it would be useful,” Moon says.

The city borrowed from lessons garnered during its earlier work with non-organic waste, which focused on encouraging residents to recycle more and throw out less.

Key was a pay-as-you-throw program where recycling is free but there’s a fee to dispose garbage.

“The idea behind pay-as-you-throw is to encourage folks to do what you want by offering financial incentives. This approach has been very successful, which is why we offer organic drop offs for free,” Moon says.

At the same time, the city is increasing pay-as-you-throw fees this budget year.

“One way residents can ease the pain of the extra cost is by using the food waste program. So, we are building on our approach to incentivize waste reduction,” he says.

Carts are intentionally placed near dense population centers. A bulk of them are near apartments, which a recent resident survey confirmed has been advantageous, as multi-unit dwellings in particular have limited storage space. Respondents said they like that they can discard their scraps when they need to, and close by.

The survey was to gauge public sentiment and Moon says, “People love it. Of about 450 respondents literally all but two thought the program was great. They thought we should expand it.”

Another common thread in the feedback was residents liked that the amenity was free to them, and the sites were clean with no scraps on the ground.

Moon’s initial concern was there would be a lot of contamination and or illegal dumping, which has not been the case. 

“I think people are committed because they have to make a point to use it and because of the community vegetable garden connection. You do not associate dumping your trash at a community garden. It’s not trash; it’s compost; it’s part of the garden,” he says.

The food scraps go to a 3-megawatt digester operated at a dairy farm two hours away. They are mixed with manure to make electricity, with the digestate used for fertilizer for the farm’s fields where hay is grown to feed the cows. The remaining fiber serves as cow bedding, which gets reintegrated into the digester after it’s no longer viable as cow bedding. So, it’s a fully circular system.

Portland pays to have the food scraps picked up twice weekly, based on number of carts and stops.  The estimated cost of collections is comparative to collecting scraps in the trash.

“We have to pay for waste disposal one way or another and the associated cost with handling and collecting materials. Now we can support Maine agriculture. We are excited about this as well as about the environmental benefits. [Composting] aligns with our philosophy and policy as a city to support the waste management hierarchy to reduce, reuse, then recycle,” Moon says.

The fact that the gardens are near population centers, and that the city owns the property, was a big part of the decision to set up there.

“That it was our property was important because we need to control the site. We do not have to negotiate with a private property owner over cost, liability, insurance, or other factors,” Moon says.

The City of Portland, Maine's Parks, Recreation and Facilities department partnered with the Sustainability office, setting up signage, helping maintain the sites, and in placing the drop-offs sites, which are positioned at the nearest tip down adjacent to the gardens so they can be easily serviced without obstructing on-street parking. 

“The decision [to host compost sites] was a no brainer for us, as our parks and open spaces provide neighborhoods with a variety of amenities, including community gardens that these compost bins are adjacent to,” says Alex Marshall, director City of Portland, Maine's Parks, Recreation and Facilities Department.

“Our parks bring the community together. Community composting bins are also a way to accomplish this and provide an opportunity for folks to limit food waste going to the landfill. And coupling the bins with the community gardens was an easy match aesthetically within our spaces,” Marshall says.

The city will be sharing data collected during the program with the University of Maine’s Mitchell Center, whose researchers will help evaluate the environmental benefits of food waste collection and assess ways to reduce municipal disposal costs through composting.