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¦.
There are two types of typhoid vaccine, one is injected and the other is given by mouth (orally). Neither vaccine provides protection for longer than 3 years, so if you will be travelling to a country where typhoid is present, and it has been about 3 years since your last vaccination, you may need to be revaccinated.he oral typhoid vaccine (Vivotif oral) can be given to children 6 years and older. The injected typhoid vaccines can be given to children 2 years and older.