This should just be a quick park & grab for most. The main thing I can't stress enough here is muggles. PLEASE BE STEALTHY! This is a very busy area. I am not giving a hint because you already have such a good one...Happy caching.
PS. Please note that dogs aren't allowed on the soccer field. Hopefully this won't be an issue, Thanks.
Cangrats to Original_Snick for the FTF!