A New York school bus driver has been arrested for aggravated DWI under Leandra's Law.  State Police arrested 61-year old William Mendez of Somers yesterday on the felony charge.  He was driving a bus from Somers Intermediate School and transporting students in town when he was stopped last Monday.  An investigation by New York State Police revealed he was under the influence of alcohol, with a Blood Alcohol Content at .22 percent.  Leandra's Law is a beefed up penalty for driving under the influence when there are children in the vehicle.