Could just be some slotted draintile pitching away from the cooler. If they had grates with holes small enough they could ensure that no big chunks get stuck in the draintile. Even if they did a cooler party a few nights a week, they would have plenty ot time for the evidence to dissappear into mother nature. Plus they are feeding the God they worship. Apologies if anything aounds morbid. Just keeping it real.