YOu fold them. A 33 gallon contractor's bag folds up to about the size of a skinny sandwich. Then put it in a 1qt freezer bag so the big bag doesn't get snagged up, sit on it (redneck vacume sealer) and close it up.
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-IronRaven

When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.