OSHA defines an excavation as any man-made cut, cavity, trench, or depression in the earths surface formed by earth removal. A trench is defined as a narrow underground excavation that is deeper than it is wide, and is no wider than 15 feet (4.5 meters). Dangers of Trenching and Excavation. Cave-ins pose the greatest risk and are much more likely than other excavationrelated accidents to result in worker fatalities.
How long does a typhoid shot last?   According to the CDC website, a booster dose is needed every 2 years for people who remain at risk.. The oral (live) vaccine lasts 5 years before another dose is neededâ¦.
Typhoid Vaccine: Injection. The typhoid injection is given only once, at least two weeks before travel. The injection lasts only two years compared with the five years of protection offered by the oral typhoid vaccine.After two years, a booster shot is needed for people who plan to continue traveling in countries where typhoid is common or who are otherwise at risk.he typhoid injection is given only once, at least two weeks before travel. The injection lasts only two years compared with the five years of protection offered by the oral typhoid vaccine.