Berms are made from used oyster and turkey tail substrate. For increased longevity, you may bury lengths of fresh hardwood under the myceliated sawdust. Finish off the berms by covering them in woodchips, leaves, straw, grass clippings, hay, etc.
A view of the compost site. The basin is the lowest point behind your berm, where you expect to collect standing water in a heavy rain event. This area should not be directly inoculated because the mycelium will likely die if it is saturated for more than 3 days. Instead, you want to focus your inoculation efforts in the berms and the floodplain above the basin.