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¦.
Remember that you will need to complete your vaccination at least 1 week before you travel so that the vaccine has time to take effect. Typhoid vaccines lose effectiveness after several years; if you were vaccinated in the past, check with your doctor to see if it is time for a booster vaccination.t a Glance. If you are traveling to a country where typhoid (Salmonella serotype Typhi) is common, you should consider being vaccinated against typhoid.