Solid or viscous substances in quantities or of such
size capable of causing obstruction to the flow in sewers or other
interference with the proper operation of the POTW, including, but
not limited to: grease, garbage with particles greater than 1/2 inch
in any dimension, animal guts or tissues, paunch manure, bones, hair,
hides or fleshings, entrails, whole blood, feathers, ashes, cinders,
sand, spent lime, stone or marble dust, metal, glass, straw, shavings,
grass clippings, rags, spent grains, spent hops, waste paper, wood,
plastics, rubber, tar, asphalt residues, residues from refining or
processing of fuel or lubricating oil, mud, or glass grinding or polishing
wastes.