Excavation Safety for Workers Specifically for Type C Soils Submitted by Dr Les LaFountain with Project Navigator, Ltd., June 2008

Trench Dangers Excavation cave-ins are a major source of fatalities within the construction industry each year During the period there were 771 fatal accidents involving excavations in the US The yearly fatality count ranged from 59 to 81 with an annual average of 70 For each excavation fatality perhaps ten times as many workers are injured, some of them with serious long term disabilities The real tragedy is that most if not all excavation accidents are avoidable.

Requirements Minimum safety requirements if employees are in the trench Protect them from a cave-in Your company must have someone who is trained in trench safety, called a Competent Person, who has made sure the trench is safe The type of soil is important to trench design and we will use the safer design in the examples

What to do Before Trench Ops Activity or Job Hazard Analysis, or similar Crew Activity Plan, or similar Utilities location needed and done? Test for low oxygen, hazardous fumes and toxic gases before entering a trench Is Excavation greater than 5 feet deep (your site may use a depth of 4 ft) and less than 20 ft? No: no problem competent person Yes: “competent person” must be on-site and must have evaluated excavation before and during work An engineer must design any excavation deeper than 20 ft.

What To Look For 20 FT Max Never enter a trench with straight, unshored sides that’s greater than 4 ft deep. Note the width to depth ratio. Don’t enter a trench deeper than 20 ft unless an engineer has designed the trench shoring Never enter a trench greater than 4 feet unless a “competent person” has designed or approved the trench.

Sloped Sides Only go into a trench >4 deep if… Sides are sloped so Width is 1.5 times the depth. If the sides are not 1.5 to 1.0, ask why And, only if a “competent person” has designed or approved the trench

Benched Sides With some exceptions, Width must be 1.5 times the depth Benches and/or slopes are OK in same excavation

Other Things to Watch For Water: None seeping, none ponding Excavation Edges No Soil piles within 2ft No Heavy equipment within 2ft Soil layers sloped into excavation Building foundation adjacent Ladder or sloped entrance every 25 ft.

Remember Anything deeper than 4 ft requires evaluation by competent person Anything over 20 ft deep needs to be engineered Excavation has to be 1.5 times wider than it is deep Slope it or bench it Other things to watch out for: Heavy equipment parked on edge of excavation Water in, or seeping into excavation Soil layers that slope into the excavation Stockpiles near edge of excavation Building foundation at edge of excavation Ladders or ramps are required every 25 ft.

10 What To Do If Excavation Doesn’t Look Right? Everybody has the right to stop work and should use it, even if you’re not sure No one can be terminated, or disciplined, or written up for stopping work because of a safety concern!