50' IC prechiller hooked up to a therminator. on the wort side, the wort runs through the therminator and then through a post-chiller (25' copper coil in an icebath).
Yes it is complex and crazy and perhaps Rube Goldberg-ish, but I have freaking >80df groundwater most of the year.
Using this method, I can get my 12gal of wort below 60df within 20min and aerate and pitch for ales immediately after I dump the CB, or only have to wait about 6 hours to get it below 50df for lagers.