Just a week after the State of the City Environment Forum had speakers who focused on ways the city could move towards zero waste, we had the opportunity to take some members on a tour of Compost Cincy. This was thanks to owner and CEO Grant Gibson being very willing to show us around the site. I’ve categorized some of the questions from our members below about the process.
Grant Gibson shows members a fresh load and explains windrow composting.
How the process works
Windrow composting is a method of aerobic composting that combines food waste and celluloid organic matter (wood chips, etc) into rows. Bacteria and enzymes break down the matter into nutrient rich compost material that is tested and prepped for sales in local gardening and retail stores. Every few weeks, a large machine turns the rows of compost to allow oxygen to fuel the process. The breakdown occurs between 120 and 140 degrees Fahrenheit.
A thermometer shows the internal temperature of a windrow.
Diverted waste streams
Companies around the city, sourcing from food processing facilities to cafeterias, are very excited to have a place to send compost waste at a cost much lower than tipping fees at landfills. Xavier University and Proctor & Gamble are examples of some of their clients, while Mr. Gibson hopes to continue to add sources such as the University of Cincinnati.
Wood carbon sources are necessary from the process, and the facility is currently receiving most of their cellulosic biomass from local landscaping companies. “They’re happy about it. Until we opened, there were only drop-off facilities on the west side and east side. If you look at the 275 loop, we’re pretty much the bulls-eye of that circle, so we’re a more convenient location for a lot of them.”
A massive chipper machine breaks down landscape trimmings into sizes that allow for aerobic composting in windrows.
Mr. Gibson hinted that there may be opportunities with the city to reinstate the city curbside yard material pickups, and has been in some discussions with them. He raised concerns that new types of broadleaf pesticides being used for yard treatment leave residue on grass clippings that don’t break down during his composting process, and could persist in his final product. This could potentially make his compost product toxic to trees where the compost is spread, so he stated very clearly that he won’t accept any type of grass clippings.
Runoff
“We’ve graded the slope of the site to collect runoff into a retention pond,” referring to a lined pond which collects highly nutrient rich liquids during rain events. The lined pond is sufficient for runoff, and discharge into the sewer system may only be necessary during a rare 100-year rainfall event.
A lined retention pond collects runoff from the windrows.
What’s under the site?
The old dump site was recently redeveloped as part of OEQ’s brownfield redevelopment initiative, which secured a consent not to sue from the EPA with regards to any possible hazardous waste that may exist underneath the site.
“We had to make sure that we didn’t disturb what’s down there. We had to show how we were going to do that.” Records of what went into the dump are virtually non-existent, as Grant explained that it had literally been just place for people to dump, not a landfill which would have been lined.
Methane does not seem to be an issue at this site, as it has been at other nearby abandoned fill sites. This is a local concern that references the Elda Landfill, which was seeping methane into many local homes, causing illness and creating an explosion hazard.
Regardless, Compost Cincy makes sure they don’t open that can of worms. “When we dug the pond, I literally had to sit and watch every scoop and make sure that nothing was exposed. If something had shown up, we would have literally had to put it into a sealed dumpster, and haul it off to the landfill.”
Overall, we were very happy to see the new site, and wish Mr. Gibson and the folks at Compost Cincy the best of luck with their exciting new business.
Have more questions about Compost Cincy? Post them below, and we’ll add them to this post.
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