In order to find this cache, you must first complete the coin challenges for Richland, Kennewick and Pasco. The coins you receive from these challenges will have the required information to allow you to find this cache.
Each of the three coins will have a North and West coordinate on the outer rim of one side of the coin (displayed as N:x W:y). When you have all 3 coins, you can then calculate the coordinates of the actual cache location - hidden SOMEWHERE within the Tri-Cities.
To find the cache, use the N & W values from the coins as follows:
North - N46 22.(RN)(KN)(PN)
West - W119 25-(KN-KW-RN).(PW)(KW)(RW)
R=Richland, K = Kennewick, P = Pasco (coin to use for value)
Congrats on getting your coins, now - go out there and get your bonus! PLEASE take only one WSGA swag item per coin set so everyone gets something. Thanks to the WSGA for providing the goodies to go in this cache!
You can check your answers for this puzzle on Geochecker.com.