Any solid or viscous materials in amounts or concentrations which
cause obstruction of the flow in the POTW, or solids greater than
one-half (½) inch in any dimension. Examples of such materials
include, but are not limited to, ashes, wax, paraffin, cinders, sand,
mud, straw, shavings, metal, glass, rags, lint, feathers, tars, plastics,
wood and sawdust, grass clippings, paunch manure, hair and fleshings,
entrails, lime slurries, beer and distillery slops, grain processing
wastes, grinding compounds, acetylene generation sludge, chemical
residues, asphalt residues, acid residues, residues from refining
or processing fuel or lubricating oil, and food processing bulk solids.