Check with your state pollution control or environmental agency and then with the EPA Regional Office for Illinois. You will probably have some local or county regs to comply with also. But 1st you need to assess your operations to identify environmental issues.
Do you generate solid waste?
Do you generate waste water?
Do you create emissions?
Do you store hazardous materials?
Do you manufacture chemicals?
Start asking questions along the lines of those above.
Do you have an EHS guru?