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Spring Gillard
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Worm Wigwam at UBC

wormwigwam

I spotted a Worm Wigwam up at UBC this week. A couple years ago when I was doing the Metro Vancouver On-Site Composting Technology Review we were investigating the Worm Wigwam at a co-housing development in Bellingham.

The Worm Wigwam is a small-scale continuous-flow vermicomposting system with interchangeable bottom and lid and plastic sidewalls. It is fed from the top and the earthworm castings are harvested from the bottom. To begin, the operator must add 15 to 20 pounds of worms to a 15 cm layer of carbon bedding material, typically a mix of shredded paper and leaves, but other materials like straw, coir, shredded cardboard, wood shavings and sawdust (avoid cedar as it is toxic to microbes). Then the food waste is buried in the bedding and eaten by the worms. The bedding needs to be topped up occasionally to ensure that the food is well buried. The carbon to nitrogen mix is roughly one to three. The leachate is not captured, it drips through holes in the bottom tray and down through the wooden deck. The worm castings are harvested by a grater that is turned manually with a handle at the side of the unit.

During our study, the UBC Alma Mater Society was piloting a Worm Wigwam as a student project. We talked to the students as well and got a tour of their operation. The unit was inside a locked garbage room then. It was on a raised wooden platform with hardware cloth (16 gauge, 1/2 inch or 13 mm) underneath for added rodent resistance. They were collecting pre-consumer fruit and vegetable scraps from one of the restaurants in the Student Union Building. The results of the pilot were very positive. The plan was to add eight more units on campus, looks like it’s happened. Nice work UBC Team!

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