Moose, I experimented many ways of ventilating the grow medium stored in trashcans and so far, those 3" perforated drain pipes work the best. And...my grow medium is more "moist" than it is "dry".
Also, insure the lid on the 20 gallon Brute trashcan is not "airtight"...all living things need 3 things: air, water & food.