Solid or viscous substances which may cause obstruction to the flow
in a sewer or otherwise interfere with the operation of the wastewater
treatment facilities. Unless explicitly allowable by a written permit,
such substances include, but are not limited to, grease, garbage with
particles greater than one-half 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, gas, tar asphalt
residues, residues from refining or processing fuel or lubricating
oil, mud, or glass or stone grinding or polishing wastes.