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Senior builds pet waste composter for shelter

Updated: Nov 29, 2023

Ramsey Bond dearly loved her dog, Summit, but she was all too familiar with the “back end” of dog ownership. In preparing to earn her bachelor’s degree in sustainability studies at Colorado Mountain College, Bond took that “back end” challenge head-on through animal waste composting.

As part of her capstone project, Bond teamed up with the Colorado Animal Rescue shelter (CARE) in Spring Valley, which is adjacent to the college’s veterinary technology farm, to build an outdoor animal waste composting system. The three-bin composter converted a mixture of the shelter’s animal waste and a local woodworker’s sawdust into composted soil that’s safe for lawns, shrubbery and flower gardens.

“They really wanted to be a part of it,” she said. “It went along with their mission of helping animals go back into the community. Now we can use the waste to keep their landscaping healthy.”

Over the years, CARE has worked to increase its sustainability by recycling, using wood pellets for cat litter and installing solar panels for electricity, said the shelter’s executive director, Wes Boyd.

With the new composting system, shelter staffers collect waste through the day in a heavy-duty plastic bucket with a screw-top lid, and empty it into the outdoor compost bin at the end of the day. Bond built the three side-by-side composting bins in an enclosed area on the warm south side of the shelter building. Fellow student Aaron Anderson, president of the CMC Sustainability Club, helped with clearing a space within the enclosed area and with building the bins.

They used scavenged shipping pallets for the framework and attached scrounged one-inch wire mesh on the sides to keep the composting material in and critters out. The bin lids were topped with corrugated sheet metal, which was donated and cut to fit by Umbrella Roofing Co. Near the bins, Bond placed two large plastic trash barrels with lids, each full of sweet-smelling sawdust provided by Daniel Oldenburg at Summit Construction. The sawdust was another waste byproduct that previously went to the landfill. A few scoops of sawdust were added to the top of each day’s waste.

The CARE composter is based on a three-stage system developed and tested in other communities: building, working and curing. The "building" bin holds the raw animal waste and sawdust. Even on a warm day, shelter staff reported that there was no odor. Once the pile is about three feet high, the label on this “building” bin is switched to become a “working” bin, and the CARE staff starts piling new waste and sawdust in a new “building” bin.

The the staff adds water to the "working" bin if needed, aiming for the pile to be lightly damp from top to bottom. Using a long-stemmed thermometer, they monitor the pile’s core temperature. Natural composting heats the pile to about 150 to 160 degrees F, which help to kill off pathogens and parasites that might be present in animal waste. As it cools down, students turns the compost and repeats the process.

The heating, cooling and turning process happens three or four times over several weeks, until the pile no longer heats up. At that point, the label on the “working” bin changes to “curing” bin. The composted waste sits, exposed to the weather, for several more months. After about a year, the finished compost is ready for use in landscaping.

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