I found a 6 nozzle 1/4" mister line For 18 bucks, that I have it attached to a short length of hose and a timer. The line is held in place at the end of the run to help cool things down. The girls think it's obnoxious, but I don't hear any complaints once the cycle ends and they resume their scratching in the wet sand. The moist sand also promotes sprouting of boss and scratch grains which the girls work hard to uncover.
http://www.amazon.com/gp/product/B000P0KSXO/ref=oss_product
http://www.amazon.com/gp/product/B000P0KSXO/ref=oss_product