I see several permits marked as expired on the ODNR web site and wondered how long the permits where good for once they received them.
Sam, Ohio revised code states 12 months in urban areas and 24 months in non-urban areas. You can download it at the ODNR site.
The non-urban areas must have fewer than 5,000 residents, or the permit is only good for 12 months.
RMC in Pa it's 1 year but "easy" to extend for reasonable delays. That's my understanding for what it's worth.