The volume balance requirements limit certain types of redesignations, unless the volume balance is met over the compliance period. For example, during a compliance period a terminal may redesignate NRLM as highway fuel as long as over the compliance period the terminal meets the required volume balance.
If a terminal has been receiving fuel designated as NRLM and delivering some of it as highway and some as NRLM, the volume balance on highway fuel could go negative during that compliance period. To offset this, the terminal would have to take delivery of the fuel designated as highway and redesignate enough of it as NRLM to satisfy the volume balance.
Question and Answer was originally posted at Questions and Answers on the Clean Diesel Fuel Rules (PDF)(135 pp, 888 K, EPA420-B-06-010, July 2006, About PDF)