Workers at a construction site in Kiwanjani estate in Isiolo stumbled on a hand grenade as they dug trenches.
Peter Kirimi said they found a rusty object wrapped in two plastic paper bags about two feet under the ground.
Explosive experts from the Kenya Defence Forces ruled out terrorism, saying the weapon was buried there decades ago and "had been fixed for testing purposes by the army".
A senior bomb expert, Sergeant Ogolla said it was not dangerous and had a worn out safety pin.
“We congratulate the residents for promptly reporting the matter to the security personnel to avoid putting their lives at risk,” he added.
Isiolo, Samburu and Laikipia residents have, in the past, found explosives left behind by the military after training.
On October 27 last year, a 12-year-boy was killed and eight others injured by a grenade they were playing with at a children’s home in Kilimani on the outskirts of Isiolo town.
On December 28 last year, at nearby Archers Post in Samburu where both the Kenya and British armies train, two children were blown up by an unexploded bomb while herding goats at Nolaibalegi-Naishamunye.
Earlier in the month, three children were killed and two others seriously wounded after UXO exploded in the same area.