WILLIAM RODERICK WHITAKER JR., 79, a retired colonel in the Army Corps of Engineers who later worked for the Alexandria Public Works Department, died of cancer July 15 at DeWitt Army Hospital at Fort Belvoir, Va.

Col. Whitaker, a resident of Alexandria, was born in Winnetka, Ill. He graduated from the University of Illinois with a degree in civil engineering and was commissioned in the Army Reserves through the Reserve Officers Training Corps.

In 1941, he was called to active duty as a cavalry officer. During World War II, he was in the 13th Armored Division in Europe. After the war he stayed in the regular Army, and in 1947 he transferred to the Engineers. In the mid-1950s he served in South Korea, but most of his post-World War II career was at Fort Belvoir, where he was chief of staff when he retired in 1960.

Col. Whitaker later worked for the Alexandria Public Works Department until retiring a second time about 1970.

His military decorations included the Bronze Star.

He was a member of the American Society of Civil Engineers and the Potomac Rose Society.

His wife, Marjorie Ludlow Whitaker, died in 1978. Survivors include one daughter, Alice Manor of Annandale; one brother, James F. Whitaker of Washington; two sisters, Mary Alice Sigvaldson of Springfield and Jeanne W. Pierron of Winnetka, and three grandchildren.