As Carl Murphy pointed out there are also pits taht appear dug for purpose.
The Military used different waste tecniques according to the lay of the land.
Vaults , privies over ravines and creeks, and the police tub where you could
just dump the stuff somewhere like a river.
 
We excavated a 1814-1817 site that was documented to have undergone a massive
cleanup and found a purpose dug pit with a jumble of material. Reports under
preperation.
 
Jim Parker