Further discussion of the recycling studies, including the methodology and limitations of the studies, can be found in the March 2007 supplemental proposal (72 FR 14178-83), and the October 2008 DSW final rule (73 FR 64673-74) and the studies themselves can be found in the docket for the 2008 DSW final rule (EPA-HQ-RCRA-2002-0031-0355).