Sewage Sludge (Biosolids) Rule (Section 405) - The Standards for the Use or Disposal of Sewage Sludge rule (40 CFR Part 503) establishes requirements for the final use or disposal of sewage sludge (i.e., biosolids) when biosolids are: applied to land to condition the soil or fertilize crops or other vegetation grown in the soil; placed on a surface disposal site for final disposal; or fired in a b