Solid or viscous substances in amounts which
will cause obstruction of the flow in the POTW resulting in interference,
but in no case solids 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, petroleum products (including
plastics, gasoline, tar, asphalt residues, residues from refining
or processing of fuel or lubricating oil), mud, glass grinding or
polishing wastes.