I would advise you to first retain the services of an experienced EB-5 attorney who will consult with an Economist who has expertise in the EB-5 area. The Economist will then determine the location of the job creating entity ( JCE) and then review relevant data to support the TEA designation for the location of the JCE.
The state agency in charge of employment for the state in which the project sits will determine the TEA based on the unemployment rates for the county, census tract, or combination of census tracts. The level required is set by USCIS regulations.