ByJohn S. McClenahen For two weeks, Washington, D.C., was rife with rumors that Treasury Secretary and former CSX Corp. CEO John W. Snow would be replaced. That's not to be. On Dec. 8, a 60-plus degree day in the nation's capital, the White House let it be known that Snow would remain. Meanwhile, down Pennsylvania Avenue at the Labor Department, Secretary Elaine Chao announced the resignation of John L. Henshaw, the assistant secretary for Occupational Safety and Health. Henshaw, who had 26 years' experience directing environmental, safety and health programs in the chemical industry before his 2001 appointment as OSHA chief, is leaving the post on Dec. 31.