EPA is responding to a rulemaking petition requesting revision of the RCRA corrosivity hazardous waste characteristic regulation. The petition requests that the Agency make two changes to the current corrosivity characteristic regulation: revise the regulatory value for defining waste as corrosive from the current value of pH 12.5, to pH 11.5; and expand the scope of the RCRA corrosivity definition to include nonaqueous wastes in addition to the aqueous wastes currently regulated. EPA is tentatively denying the petition, since the materials submitted in support of the petition fail to demonstrate that the requested regulatory revisions are warranted. The Agency is also soliciting public comment on this tentative and the questions raised in this action. Comments must be received on or before 10 June 2016. POC is Gregory Helms, Materials Recovery and Waste Management Division, Office of Resource Conservation and Recovery, (5304P), EPA, 1200 Pennsylvania Avenue NW., Washington, DC 20460; tel: 703-308-8855; email: corrosivitypetition@epa.gov(Federal Register; 11 April 2016 [Proposed Rules], pages 21295-21308).