The study included a review of known past failures of trench excavations, and also the current technical standards and statutory requirements for trench excavations. The study has revealed that, between 1986 and 2000, fifteen reported failures associated with trench excavations resulted in 10 deaths and 4 injuries. In a very serious single incident in 1966, a retaining wall collapsed killing 6 people and injuring 16 others. Trench excavation at the toe of the wall was found to be the main cause of the collapse. The study also found that a number of significant landslides in recent years, which resulted in injuries and serious social disruption, were related to trench excavations adjacent to slopes.