Is it possible to ID the camp based on the building? Fort Myer or the War College, perhaps? Both of them still use old structures.

These stoves seem to be buried in the ground in trenches to retain the heat and cook more efficiently outdoors. The men must be preparing beans or readying water for a huge pot of potatoes. I see no spuds in the image but I do see evidence that they've peeled them and wiped their hands all over their aprons. At the turn of the century it didn't take much to be called a cook. At least the pots look cleaner than the cooks' hands and arms.

with this dipper full of gravel.

I'm getting hungry just watching them! It has to be beans or potatos. Where's the smoke?