Sustainable Composting Project:
The City of Yorkton Story

Yorkton is a growing Saskatchewan Community with a population of 18,000, located on the province's eastern side on Highway 16 (the Yellowhead). In the fall of 2007, Yorkton City Council passed a resolution that gave Yorkton the goal of achieving zero waste status by 2025. It was a general resolution with no specific action or financial commitments attached. In October 2007, the Saskatchewan Waste Reduction Council (SWRC) received approval for a two-year Sustainable Composting Project. SWRC needed some community partners interested in working on composting. A call to Michael Buchholzer, Director of Environmental Services for the City of Yorkton, proved to be very well timed.

In 2007, the citizens of Yorkton had access to depot and curbside pick-up recycling services for materials such as plastics, glass and cardboard. There was, however, no large-scale composting done by the city, or active promotion of backyard composting. Yard and food wastes make up 50% of household garbage in the warmer months, so composting is an obvious approach to help achieve that lofty zero waste goal. With a stockyard and grain handling facilities already active and two canola crushing plants in development, there were some easily diverted compostable waste materials being generated by businesses as well.

Yorkton's landfill is located a few kilometers north of the city. It is not equipped with a scale at this point, so incoming materials can only be tracked by volume. The city's household waste is collected by a contractor. At present, some households have single family garbage cans, others share larger multi-family bins. There is a plan to gradually change the system to single unit bins. Early discussions between Yorkton city employees and SWRC staff identified interest in collecting information about current levels of backyard composting and promotion of that activity. There was also interest in trying large-scale composting on a pilot basis. A proposal describing how SWRC and Yorkton could work together was drawn up, and work began in the spring of 2008.

The work on backyard-scale composting began with information collection. A door-to-door survey done by students in the summer of 2008 indicated that 15 to 20% of residents were already doing some form of composting and another 15% were interested in trying. In 2009, SWRC staff held a weekend Master Composter training session for city employees and interested citizens. Those attending reported a useful, hands-on learning session that left them feeling confident about improving their own home composting as well as helping others get started or solve problems. City arborist Sharon Loster was one of the students at the class and held a composting class for the public in the fall of 2008.

At the larger city scale of composting, Yorkton had all the pieces required for a low-cost pilot project: a suitable site, interested people, and easily available compostable materials.

The site: Yorkton's composting pilot project was carried out at the landfill site. That site is close to the city, had space available on land with a heavy clay soil, and was already an approved site to "land farm" or spread and till in processed, dewatered bio-solids (processed sewage). The existing fencing, controlled entry, and access to machinery and operators working on landfill duties added to the "ready to roll" state of this site.

The people: If there is a secret or magic ingredient in a compost program, it is the people. Composting is an art as well as a science. Interested, informed people, who are willing to experiment a bit, make a huge difference in how successful a composting program will be. Yorkton was able to bring an excellent mix of people to the process. Albert, the payloader operator, Dan, the summer student, Michael, the director of environmental services, and many others brought this composting pilot from idea to reality in short order.

The materials: The composting process is carried out by micro-organisms that like to eat their way through a variety of materials. The Yorkton stockyard had to haul its manure a considerable distance, and so found the composting program an excellent match with its needs. The local golf course mulches portions of its greens with flax straw every winter and sent that material for composting. Over time, more materials were added: spoiled grain, a fertilizer spill/soil mix, wood waste, and water-damaged bales of cardboard were shredded to add to the material mix. Local commercial lawn-mowing companies were invited to drop off clippings but none took advantage of the opportunity.

SWRC staff person Larry Mullen helped the City of Yorkton employees assess their situation and develop the composting process. Materials were mixed with a payloader and organized into long piles called windrows. The windrows in Yorkton were 4 to 6 feet height, about 13 feet wide and 400 feet long. The windrow height had to be kept fairly low because of the system used to water them. As materials compost, the volume decreases. When windrows are actively managed, they are reshaped over time to account for the shrinkage.

Moisture is a critical part of the composting process. In order to let the microbes work, the materials must be kept as moist as a wrung-out sponge. There was no water on site, so the city received permission from the Ministry of Environment to use liquid processed bio-solids (15% solids) to add moisture to the windrows. The bio-solids were trucked to the site in a tank and added to the windrows directly from the tank using a pipe in a drive-by operation. In the spring of 2009, the city experimented with mixing this liquid in a frozen state with materials that had been delivered for composting. Although it took longer for the whole windrow to thaw, the experiment was considered a success because the windrow composted well, and needed less additional moisture throughout the season.

When composting programs use materials like bio-solids, it is important to make certain that the finished product does not contain disease-causing bacteria. This is achieved by making certain that a turned compost windrow reaches a temperature of at least 55C for 15 days during its active decay period. It is the compost microbes themselves that release the heat. The temperature of a windrow is a good indication of how the compost process is proceeding. The windrows in Yorkton were checked for temperature on a regular basis with a four-foot long thermometre. As the compost process moves to completion, the temperature in the windrow drops to the same as the surrounding temperature.

Materials composted in outdoor windrows can be completely decomposed in 12 to 20 weeks of non-winter weather. Fully composted materials have only about half the volume of the starting materials. The finished compost is a dark, crumbly early-smelling material. In the fall 2009, the Yorkton pilot project had produced 1760 cubic yards of finished compost. Various uses for the compost are being considered. Some of the material will be used on site to cap the landfill. Yorkton Public Works and Leisure Services will also use some for other city projects.

Yorkton is pleased with the results of the pilot project and plans to continue composting materials on the current site. In co-operation with SWRC, Yorkton hosted a field day in June of 2009 so that others interested in composting could see their operation.

Material composted in pilot program:

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