The shut down I'm sure refers to the hauling of ore from the sites at higher elevation.

"They already have stockpiled 10-12,000 tons of tailings and want 20,000 tons at the Mill before they shut down that operation for the winter."

It wasn't clear in the post, but "that operation" refers to the trucking. They want 20k tons stockpiled at the mill before they shut down trucking for the winter so that they have enough to last until trucking can resume in the spring. The mill will continue to run during the winter, they just have to make sure they have enough ore stockpiled.

Interestingly, in a recent PR the rate of processing was 3000 tons in 3 months, or 1000 tons per month. If they need 20k tons to last the winter, does that mean that they will be increasing the processing rate? 20k tons over 4-5 months is 4-5000 tons per month.