Three codes could be found in the SIGNUP SHEET FOR CHICAGO INGRESS RPE post on the Investigate Ingress blog.
[1] .eq93olaj.229py
[2] gqxjgeeprssoplichciu
[3] co4kb6do5y94tv
Code #1
Observations
You just have the wrong keyboard
Code #2
Observations
Try to spot the keyword, then it’s easy
Code #3
Observations
14 characters with the right amount of numbers for a valid passcode