This cache can help with several challenges. Rhyme Time Challenge, California Multi Cache Challenge, and maybe more.
This is a simple 2 stage multi. GZ should take you to a city light pole where you will see an alphanumeric designation. Convert the letter to its numeric value, add the 4 digits together to get a 2 digit sum, then square that sum. Subtract this number from 510 to get your North coords (N38 01.xxx). Subtract this same number from 420 to get your West coords (W122 17.yyy).
Final coords check sum for ALL digits: 35