Sandra was born in Spokane, Washington to William and Betty McDowell. The family moved to Kennewick where she graduated from Kennewick High School in 1969. Sandra married her first husband at twenty-one years old. They were married ten years and had four children: Leslie, Clint, Grant, and Amanda.

She attended CWU where she obtained her bachelor's degree in nutrition. Sandra then moved back into the Basin City area where she worked for a sub-contractor at Hanford while also obtaining her master's degree in environmental science from WSU Tri-Cities. She met her second husband during this time, and they were married until his death in 2007.

Sandra's greatest joy in life was her family where she was blessed with fifteen grandchildren: Zachary (Chandler) Whitby, Kyle (Nickole) Whitby, Jared (Madison) Whitby, Brinley (Ryan) Bake, Ashlyn Whitby, Colby Whitby, Brittany Hansen (Luke Nilsen), Courtney Hansen (Devon Stone), Shelby Hansen (Joshuah Campbell), Carine (Cas) Cedillo, Kaden (Ashlyn) Efterfield, David Efterfield, Bryce Efterfield, Andrew Efterfield, Averie Efterfield and many great-grandchildren.

Sandra is preceded in death by her parents William and Betty McDowell, brother William McDowell, and sister Christine McDowell. Her second husband, William Gaines. Her two sons, Clint Hansen and Grant Hansen.