Vermicomposting is not clearly covered by most states' composting regulations, so large-scale vermicomposting *by itself* is in a bit of a gray area.
However, large-scale vermicomposting almost always requires "pre-composting," which is a partial hot composting process to stabilize the material and kill any pathogens present.
If you need to pre-compost on-site, this pre-composting must meet the US EPA's PFRP (Processes to Further Reduce Pathogens) standards including, but not limited to:
- 131°F temperature or higher for 3 consecutive days or more in an aerated static pile system
- 131°F temperature or higher for 15 consecutive days or more plus 5 turnings of the windrow
As always, consult with regulations.
In general, states are fairly permissive of composting and may not require a permit to compost material that is generated on-site. Expect further restrictions in some states if waste generated off-site is brought on site for composting or if you plan to compost material other than vegetative waste or animal manures.
You can almost certainly expect to need permitting for composting waste if you are collecting tipping fees for accepting waste generated off-site.
If you are bringing in waste from off-site that is already composted and ready to feed to the worms and you are not collecting fees for accepting that composted waste, the regulations around that are far less clear. Although you should consult with local authorities before operations, it is unlikely that your state's environmental regulations address vermicomposting specifically.