Risk Management Department Site Safety Teams 4/14/2017 Risk Management Department Excavation Safety May, 2008 Risk Management Department

Excavation Safety Introduction Site Safety Teams 4/14/2017 Excavation Safety Introduction In order to prevent injuries and improve work productivity, APS has developed this training to provide you the knowledge to stay safe when working in and around excavations. Risk Management Department

Excavation Safety Introduction Site Safety Teams 4/14/2017 Excavation Safety Introduction About 400 U.S. workers die in trench-related accidents each year About 6,400 are seriously injured For this reason it is important to understand how to stay safe in and around excavations Risk Management Department

Excavation Safety Introduction In this training we will cover: Site Safety Teams 4/14/2017 Excavation Safety Introduction In this training we will cover: What is a trench? Soil characteristics Collapse types Shoring techniques Safety requirements Risk Management Department

Excavation Safety What is a Trench? Site Safety Teams 4/14/2017 Excavation Safety What is a Trench? A narrow excavation that is deeper than it is wide No more than 15 feet wide at bottom Walls will eventually fail Risk Management Department

Excavation Safety What is a Trench? Site Safety Teams 4/14/2017 Excavation Safety What is a Trench? Failure of trench walls results in cave-in: Soil or rock that suddenly falls or slides into an excavation Sufficient quantity to entrap, bury, injure, or immobilize Soil gravitates downward, pressure pushes soil inward toward the trench Bottom third of wall typically fails first Soil above the collapsed lower wall follows Risk Management Department

Excavation Safety What is a Trench? Cave-ins are dangerous to workers: Site Safety Teams 4/14/2017 Excavation Safety What is a Trench? Cave-ins are dangerous to workers: Soil weighs 125 lbs. per cubic foot A worker can be crushed by soil, rock, or an object Suffocation—even if worker’s head is not buried, soil prevents chest expansion Worker becomes immobilized by soil’s suction effect Risk Management Department

Excavation Safety Soil Characteristics Site Safety Teams 4/14/2017 Excavation Safety Soil Characteristics Type A (most stable) — dense and heavy clay Type B — silt, sandy loam, medium clay Type C (least stable) — gravel, loamy sand, soft clay Risk Management Department

Excavation Safety Soil Characteristics Site Safety Teams 4/14/2017 Excavation Safety Soil Characteristics Factors affecting soil strength: Water Vibrations Erosion and Weathering Excavation Depth Slope Steepness Degree of Soil Compaction Risk Management Department

Excavation Safety Soil Characteristics Signs of impending collapse: Site Safety Teams 4/14/2017 Excavation Safety Soil Characteristics Signs of impending collapse: Fissures or cracks on excavation face Slumping of material from excavation face Bulging or heaving of material at the bottom of excavation wall Sinking of excavation’s edge Ravelling, or small amounts of material (e.g., pebbles) trickling into excavation Risk Management Department

Excavation Safety Collapse Types Site Safety Teams 4/14/2017 Excavation Safety Collapse Types There are four types of trench collapses: Spoil Pile Slide Side Wall Shear Slough–in Rotation Risk Management Department

Excavation Safety Collapse Types Spoil Pile Slide - Site Safety Teams 4/14/2017 Excavation Safety Collapse Types Spoil Pile Slide - Collapse of material that has been removed from the trench back into the trench Risk Management Department

Excavation Safety Collapse Types Side Wall Shear - Site Safety Teams 4/14/2017 Excavation Safety Collapse Types Side Wall Shear - Collapse of side wall from the top into trench Risk Management Department

Excavation Safety Collapse Types Slough-in - from middle of wall Site Safety Teams 4/14/2017 Excavation Safety Collapse Types Slough-in - Collapse of side wall from middle of wall Risk Management Department

Excavation Safety Collapse Types Rotation - Collapse of bottom third Site Safety Teams 4/14/2017 Excavation Safety Collapse Types Rotation - Collapse of bottom third of trench wall causing secondary wall collapse Risk Management Department

Excavation Safety Shoring Techniques Site Safety Teams 4/14/2017 Excavation Safety Shoring Techniques Engineers are often required to design shoring, which is a construction procedure used specifically to maintain the stability of the walls of an excavation and provide protection to workers who may enter the excavation Risk Management Department

Excavation Safety Shoring Techniques Site Safety Teams 4/14/2017 Excavation Safety Shoring Techniques To mitigate the danger of cave-ins, there are 4 main techniques to shore trench walls: Wood Support Screw Jacks Hydraulic Shores Trench Cages Risk Management Department

Excavation Safety Shoring Techniques Wood Support Site Safety Teams 4/14/2017 Excavation Safety Shoring Techniques Wood Support Risk Management Department

Excavation Safety Shoring Techniques Screw Jacks Site Safety Teams 4/14/2017 Excavation Safety Shoring Techniques Screw Jacks Risk Management Department

Excavation Safety Shoring Techniques Hydraulic Shores Site Safety Teams 4/14/2017 Excavation Safety Shoring Techniques Hydraulic Shores Risk Management Department

Excavation Safety Shoring Techniques Trench Cages Site Safety Teams 4/14/2017 Excavation Safety Shoring Techniques Trench Cages Risk Management Department

Site Safety Teams 4/14/2017 Excavation Safety Safety Requirements At least one worker in each work crew must be experienced in the type of work being performed in excavations At least one worker should be trained in first aid Risk Management Department

Excavation Safety Safety Requirements Site Safety Teams 4/14/2017 Excavation Safety Safety Requirements Protecting the area around the excavation: All work areas must be adequately guarded or barricaded by fences, guardrails or a covering sufficient to prevent persons from falling into the excavation Excavations might endanger stability of buildings, walls, other structures Sidewalks, pavement not undermined unless supported to prevent collapse on excavation workers Risk Management Department

Excavation Safety Safety Requirements Site Safety Teams 4/14/2017 Excavation Safety Safety Requirements Protecting workers in excavations: Protect workers from loose rock/soil that may fall from an excavation face Use scaling to remove loose soil Use protective barricades, such as shoring or shields Protect workers from material or equipment that could fall into the excavation Keep material/equipment at least 3 feet from edge Use retaining devices Risk Management Department

Excavation Safety Safety Requirements Site Safety Teams 4/14/2017 Excavation Safety Safety Requirements Protecting workers in excavations: Excavation sites cannot be covered with anything such as piles of excavated material or excavation equipment which might accidentally fall into the excavation Risk Management Department

Excavation Safety Safety Requirements Site Safety Teams 4/14/2017 Excavation Safety Safety Requirements Protecting workers in excavations: Trenches 4 feet deep or more must have exit means within 25 feet of every worker Use fall protection Do not work on sides of sloped or benched excavation above other workers For parallel construction have a worker on top to watch excavation walls to warn trench workers of potential hazards Risk Management Department

Excavation Safety You are finished! Site Safety Teams 4/14/2017 Excavation Safety You are finished! You have finished the Excavation Safety training. Download the quiz from the Risk Management website’s training page. Print the form and be sure to write your name, location and employee number in the spaces provided. Complete the ten questions and have your supervisor send it to the Risk Management office Risk Management Department