Original Work Two workers were assigned to replace a water valve located in an underground concrete vault. After removing the manhole cover, worker...

Original Work Two workers were assigned to replace a water valve located in an underground concrete vault. After removing the manhole cover, worker #1 climbed down the ladder into the vault. Worker #1 collapsed and became unconscious within seconds of reaching the bottom. Worker #2 went down the ladder to rescue worker #1 but was quickly overcome by the lack of oxygen. Both workers died at the bottom of the vault.