Digging out of the winter snow has become a costly affair for the Georgia Department of Transportation. Preliminary estimates released Monday show that, between employee hours and materials used, such as salt, gravel and brine, the DOT spent $681,408 on last week’s winter storm in District 1 — or Northeast Georgia — alone. That’s more than the $624,850 in fiscal 2012-13 and 2011-12 combined, according to data compiled by Teri Pope, the DOT’s district spokeswoman.