Unloading a ng D&RGW high sided gondola

I’m in the process of designing a new model railroad that incorporates a narrow gauge segment. I fell in love with the D&RGW high sided gon and want to use it in mineral service. I understand that the Grande used these cars hauling coal and limestone, but I have no clue how they were unloaded. I would need to build an unloading dock but do not know how to design it. They appear to have solid bottoms. Drop sides?? Shovel by hand?? Does anyone have any ideas??

The high sided gondolas used hauling coal and limestone from Crested Butte and Monarch went to Salida where they had a transload car dumper. There were some drop bottom gons (sides a little shorter than high sided) for coal off the Baldwin branch that was used locally around the “narrow gauge circle”. Some mineral concentrates were hauled in box cars, I believe in sacks.