Police say the woman called 911 at about 10 a.m. after finding the device, which was six to eight inches long. The woman told dispatchers she was cleaning the garage at her Langridge Loop home when she spotted the metallic-looking object in a cabinet.
Olympia police officers arrived at the home soon after and began examining the device. Police say the pipe had caps on both sides and was equipped with a fuse.
Officers put the bomb in a safe area outside and called in the Washington State Patrol Bomb Unit, who later disposed of the device.
Investigators have no idea who put the bomb in the garage or how long it had been there.