Note: This is the first of a two-part series on trench safety and the need for proper shoring. In Part 2 of the series, a cave-in survivor dispels the common belief that only deep trenches are dangerous.On Jan. 13, a contractor in Oakland, California, survived being trapped up to his waist in sand and dirt in a 15-foot-deep trench.Rogelio Esparza, 41, was attaching a lateral to a mainline at about 12:30 p.m. when the walls of the trench he was working in collapsed. Officials say plywood used to shore up the walls gave way, trapping the plumber’s feet in sand and debris in a
