Trench for the First Responder

Orientation This information is intended to give the first-in company an idea of what to do and how to go about it safely.

Terms to Know Angle of Repose – the greatest angle above the horizontal plane at which loose dirt will lie without sliding. Back Fill – the refilling of a trench, or the material used to refill a trench, or to fill a void between two surfaces. Spoil Pile – the material excavated from the trench.

More Terms to Know Fin Form – ¾”, 14-ply, arctic white birch. Strong Back – a 2 x 10 or 2 x 12 attached to fin form to create a panel for shoring the wall of a trench. Struts – the horizontal bracing between the trench walls. Uprights – vertical supports, usually 2 x 8’s, the depth of the trench. Ground Pads – 4x8 or 2x8 sheets of plywood used to disperse weight around the edge of the trench.

Where do we see trenches? Commonly seen occupied and unprotected Public works routinely work in trenches. Pipeline & cable installation. Areas of new construction (water, sewer)

Fin-form & strong backs Air-Shore strut Paratech strut Back fill (wood & dirt) Ground pads

Use of multiple types of shores Fin-form & strong backs Ground pads Whalers Escape ladders

OSHA Defines a trench as an excavation that is deeper than it is wide and is no more than 15’ wide. Has regulations governing operations in trenches 5’ deep or deeper. Regulations apply to rescues. Provides guidelines for trenches up to 15’ wide and 20’ deep. Custom engineering is required by a Registered Professional Engineer beyond those limits.

60 to 65% OF ALL FATALITIES ARE THE WOULD-BE RESCUER Lack of knowledge Lack of training Compassion for the victim

Trenches are Dangerous Once earth is disturbed, pressure begins to act on the trench walls. Sooner or later all trenches cave in. There is no way to predict when a trench will fail.

Note the deterioration to the left corner

Vibration Hazards All heavy equipment should be turned off and secured (take the keys and block the tires). All sources of vibration should be eliminated for 300’ in every direction. This includes roadways and railways.

Backhoes Backhoe operators will insist they can dig the victim out. OSHA statistics are riddled with cases of disembowelment and decapitation. Backhoe operators cannot tell the difference between a rock and a body. Weight of the backhoe adds to instability of trench walls. Vibration likely to speed up secondary collapse

Atmospheric Hazards The victim may be the result of bad air in the trench and have no actual trauma. Air should be monitored every 15 minutes for O2, CO, H2S and combustibles. Rescuers can fall victim to the same bad air if it is not checked regularly. O2 permissible exposure limits: 19.5%-23.5%. Methane Gas Flammable Limits: 5.0%-15.0%.

Public Utilities as a Hazard Many trenches are dug for utility maintenance or installation. Utility cables and pipes can add to trench instability. Electrical utilities can pose a threat to both the victim and the rescuer. Broken sewer or water lines may fill the trench, causing a drowning potential for the victim.

CONTACT WITH UTILITIES CAN BE DANGEROUS & CAUSE DISRUPTION TO SERVICE Critical communications CONTACT WITH UTILITIES CAN BE DANGEROUS & CAUSE DISRUPTION TO SERVICE Fire protection Power grid Traffic flow GAS SERVICE ROADWAY UNDERMINING

Heavy equipment can fall into the trench trapping workers Workers can be struck by operating heavy equipment

Digging their own grave…

Seattle, WA 8/8/2000 Worker killed Rescuers using camera to locate victim’s body

Lebanon, MO 1989 Hit 10” propane pipeline Killed operator

1996 - Operator burned after hitting 8” gasoline pipeline

St. Paul, MN - 1993 City crew working on sewer line hit natural gas line Killed 3, injured 11

1988 Hit propane line 3 Workers injured

Dirt as a Hazard One cubic foot of dirt weighs 90-145 lbs. The average collapse is 1.5 cubic yards (4000 lbs.). The average victim buried under 2 feet of dirt will be covered by 3000 lbs., about 1000 lbs. of that will be on his chest. The speed of collapsing dirt is often less than 1/10th of a second.

Time…Time…Time… The average trench rescue takes between 4 and 10 hours. Long rescue time allows for further deterioration of trench walls. Rotation of rescue crews necessary to keep people fresh.

The First-In Company Apparatus should be located no closer than 50’ to the trench and should be shut down. Locate the victim and try to find out what was being done at the time of the accident from someone else on the scene. Approach the trench from the end, never from the side and stay as far away as possible.

The First-In Company If the victim is conscious, he may be able to rescue himself if a ladder and/or shovel is lowered to him. Keep everyone back from the trench and shut down all machinery on the scene. Shut down all roads and railways for a 300’ radius from the scene.

The First-In Company The location of an unconscious or trapped victim can be marked with paint or dry-chem at the edge of the trench. Ground pads will need to be laid around the edge of the trench. The spoil pile must be moved a minimum of 2’ away from the edge of the trench. This must be done while working off ground pads.

Water, Water Everywhere… Prior to the rescue team entering the trench, all water must be evacuated. This includes water from a main break, ground water and rain water. Small amounts of water can be removed with a sump pump in a 5 gallon bucket. Larger amounts of water or water which is flowing can be removed with a vac-truck. The truck must be set up 300’ away and have a safety valve in line with the vacuum hose.

Incident Command Establish a trench team command structure Rescue Officer (required) – Officer in charge of the rescue and designates other rescue sectors. Rescue Safety (required ) – May be in addition to the scene safety officer and trained to the level of the incident. Rescue Operations – Officer who runs the rescue.

Medical Care for the Trench Victim Establish medical care for the victim as soon as protection is established and victim is accessed. Prepare for open & closed fractures, chest injuries, spinal injuries, crush syndrome, hypothermia, dehydration and hypoxia. Give the victim a head, eye and respiratory protection as soon as possible.

Trench Rescue Hazards Hazards are not obvious Secondary collapses are common Dirt is heavy and moves fast Rescues are usually long-term operations Backhoes are not safe for victim rescue OSHA has trench limits and regulations Buried utilities can pose a threat to rescuers Impact or entrapment from falling debris or equipment Unprotected trenches are dangerous There may be inadequate equipment for shoring Possible legal liabilities for fire officers

??????