Swad is a layer of dirt, shale, or low-quality carbonaceous material lying immediately below the workable coal and above the true floor rock. Miners must often cut through or remove it to get a clean floor for haulage or to avoid contaminating the extracted coal. It is a nuisance layer that adds dead work to the extraction process.
Heard on the job
The cutter is bogging down in that swad, so raise the drum a few inches to stay in the clean coal.