Welcome to Michigan’s Region 2 Trench Rescue Awareness Training Program. This program meets and exceeds the NFPA Awareness requirements.
At the conclusion of this program, you will be able to do the following:
Identify the need for trench rescue.
2. Identify the resources needed for trench rescue.
3. Activate a rescue response system.
4. Control the site and manage the scene.
5. Identify and mitigate hazards. 6. Identify causes of collapse and common collapse patterns. 7. Assist with a non-entry rescue. TRENCH RESCUE AWARENESS
Over the past decade, trench rescue has proven to be the most common technical rescue in Michigan’s Region 2. One of the reasons, for this, is the increase in the underground construction activity. Michigan’s “Miss Dig” system has the largest volume of any one-call center in the United States. During the summer months, “Miss Dig” receives an average of over 4,200 requests per day. As the underground utility infrastructure ages, more and more repairs are required. Additionally, every new home or business requires underground construction and utilities. The combination of these factors has created a high frequency of people working below grade and a high risk for trench rescues. As a result, the need for trench rescue exists in virtually every community in Michigan. 1. Identify the Need for Trench Rescue
Trenches dug for new construction connect new structures to existing utilities. They commonly have a long and narrow appearance like the trench in this picture. New Construction
Repairs Trenches dug to repair broken utilities are often as wide as they are long. The aging utility infrastructure and the new construction in Region 2 create a high frequency of underground construction work. Failure to comply with safety standards has required mutiple trench rescue operations.
Awareness level responders should be able to define the following:
Straight Run Trench
Severe Environmental Condition
Bell Bottom Pier Hole
Excavation: Any man-made cavity or depression in the earth’s surface (including its walls, floor and lip) formed by earth removal. For rescue purposes an excavation is wider than it is deep. Excavation Definitions
Trench: A narrow excavation which is deeper than it is wide, with a maximum width of fifteen (15) feet, measured at the floor (bottom). Trench Definitions
Floor Floor: The bottom of a trench or excavation. Definitions Floor Floor
Wall Wall : The vertical or inclined earth surface formed as a result of excavation work. Definitions
Lip Lip : The ground level area around (360 degrees) a trench or excavation. Definitions
Spoil Pile Spoil Pile: Soil excavated (removed) from the trench, commonly found on the trench lip. Definitions
Straight Run Trench : A trench which does not cross or meet another trench. Definitions
Intersecting Trench: A trench which meets or crosses another trench. Usually takes an L-shape, T-shape or X-shape. Definitions
Supplemental Shoring- Supplemental sheeting and shoring includes operations that involve the placement of additional sheeting/shoring whenever digging exposes more than 2 feet of wall below the bottom of the initial strong-back. Definitions
Severe Environmental Conditions - Severe environmental conditions include operations involving frozen soil, running soil (e.g., gravel, sand, liquid), severe weather (e.g., heavy rain, wind, or flooding), or night (dark) operations. Definitions
Bell Bottom Pier Hole - A tubular shaft with a wider bell shaped cross-section at it’s base for support. Created for foundations and footer construction. Definitions
Soil - A thin layer of material on the earth’s surface. It is made up of many things such as weathered rock, decayed plants and animal matter. Weathered rock takes the form (particulate) of sand silt or clay. Most soil is a combination of sand, silt and clay. Definitions
Running Soil - Any free-running type of soil, such as sand or gravel, whose strength depends on friction between particles. Unsupported running soil will not hold a vertical wall cut. Definitions
Saturated Soil - Soil which has water seeping through the walls. Typically a result of a broken water main but could result from a high water table and very rainy conditions. Definitions
Compact Soil- Soil that sticks together long enough to hold a vertical wall. Most trench cave-ins occur in soil that is compact. Definitions
TYPES OF TRENCH RESCUES Cave In: Workers unable to escape due to: Dirt from spoil pile slides or wall collapse Bedding material (sand/stone) accidentally dumped into the trench Dirt and pipe resulting from pile slide or wall collapse
Cave In: Workers unable to escape due to:
Dirt from spoil pile slides or wall collapse
Bedding material (sand/stone) dumped into the trench
Dirt resulting from spoil pile slide or wall collapse
Non-Cave In: Workers unable to escape due to:
Pipe rolled into the trench
Failure of improperly installed shoring
Heavy equipment rolled or fell into trench
Boulder dislodged and fell into the trench
2. Identify the Resources Identifying the resources necessary to conduct safe and effective trench and excavation emergency operations. It is not unusual to read about a trench rescue where a hundred firefighters took ten hours to remove a victim from a trench. People trained and equipped for firefighting operations are not the resources that are needed to perform a trench rescue. In the fire service, “If we don’t what to do…we will keep sending more of what we have.” Ron Zawlocki, Battalion Chief (Retired), City Of Pontiac, MI
2. Identify the Resources Needed to Perform a Trench Rescue So what resources do we need at a trench rescue? 1. A trench rescue team trained and equipped at the “technician level”. A response of twenty-five to thirty trench rescue technicians will provide enough personnel with a tactical reserve to handle the vast majority of trench incidents. 2. Services and equipment resources that support the trench rescue team. We have divided these into a two tied response plan. Tier One resources should be dispatched on all trench rescue calls. Tier Two services are requested by the incident commander based upon the scope and magnitude of the incident.
Technician Level personnel should be trained and equipped to handle:
Deep Trenches (up to 20’ deep)
Severe environmental conditions
Extrications that involve supplemental shoring
Cave in potentials that can not be resolved by methods other than traditional sheeting and shoring
The following Michigan OSHA laws are used as safety guidelines during “ rescue operations ” and are followed as legal regulations during recoveries. Part 9 : Excavation, Trenching, Shoring Part 90 : Confined Space Entry Part 74 : Fire Fighting MI-OSHA Rules
Physicians and Paramedics serving as Rescue Medics must be trained to at least the trench rescue operations level.
Rescue Medics (include USAR Medics and Physician Rescue Teams). Rescue Medics must train with and be active members of the Trench Rescue Team.
Heavy Equipment Operators Heavy equipment operators who are trained in trench rescue are valuable resources at a trench incident. These operators must be active members of the trench rescue team. In Region 2, Operators come from Local 324 and are members of MI-TF1.
Police Local police are a Tier-1 Resources that are utilized for traffic control, crowd control and force protection.
Vac Truck Vactor truck equipment and operators can be utilized to remove soil from the victim before rescuers get into the trench. Vac Truck operators should be familiar with Trench Rescue procedures and should train with the Trench Rescue Team.
Technical Advisor Complex trench and excavation rescues may require the use of Technical Advisors. These advisors may include experienced Trench Rescue Team Members and Trench Rescue Instructors.
Tow Truck Tow truck companies, which have large, low pressure airbags, that are capable of up righting train cars and semi-trucks, should be on the Tier-2 Resource List. These bags can be used to support trench walls and fill in voids created by cave- ins.
Engineers Tier-2 resources should include Structural and Geological Engineers. These engineers should be part of the trench teams training and exercise program.
Confined Space Rescue Team A Confined Space Rescue Team should be part of your Tier-2 Resource List. Complicated entry and extrications may utilize confined space rescuers.
Haz Mat Team Haz Mat Teams may be utilized at Trench Rescues which have been dug in contaminated soil or have had spills or releases into the soil.
Search Teams Victims who are completely buried may require the use of Specialized Search Teams. Canines, cameras, acoustic and seismic devices can be used to local buried victims. MI-TF1 can deploy a Search Strike Team with these capabilities.
Rehab Technician level trench rescues are often multi-hour incidents. Responders must be hydrated, feed and rested during their operational period. Resources for responder rehabilitations include Red Cross and Salvation Army.
Equipment needs at a trench rescue are vast and varied. The Region 2 USAR Response system has created a minimum equipment list. That list can be found in the Appendix of this program. Equipment
As a minimum trench rescue equipment should address the following:
Anyone who witnesses a trench accident should begin to activate the system by calling 911.
The incident commander will activate the response system through a pre-arranged trench response system.
3. Activate the Response System In most communities the first response to a trench rescue will be a fire engine and EMS Unit. While these first responders can perform some important awareness level initial actions they do not bring with them the equipment and trained personnel needed to perform a trench rescue. NFPA Standard 1670 requires that every firefighter who might be sent to a trench rescue has a minimum of awareness training. Responders who are expected to perform rescue functions need to have operation and/or technician level training.
3. Activate the Response System In addition to the first due engine and EMS unit, the response system must include: the services and equipment listed as Tier-1 resources and a dispatch capability that can quickly move the resources to the scene. Tier-2 resources may be called out after an assessment and size-up have been completed. It is very important that the Tier-1 and Tier-2 services and equipment are pre-arranged. Agreements with service and equipment providers must be made before a trench accident occurs. 24/7 contact arrangements are needed and must be part of the resource list. While not every community can have its own Trench Rescue Team, every community can and should have a Response Plan and Resource List.
The first arriving officer shall take command and begin the size up. The size up will include the following:
Situation – Determine what has happened. Is this a “Cave In” or “Non-Cave In” incident? Victims of a cave in will be injured or trapped by soil. Non-Cave In accidents may include: Medical problems, Trauma, Electrocutions and Hazardous atmospheric conditions.
Hazard Assessment – Determine the hazards in the general area and the rescue area (See Section 5 - Hazard Recognition).
Victim Information – Determine how many victims are injured or trapped. Assess the victims injuries and decide if this is a rescue or body recovery.
Trench Detail – Determine if this is a trench or Excavation (See Section 1 – Definitions). Measure the depth and width. Evaluate the soil as: “Compact”, “Running” or “Saturated”.
Resources – Assess the resources responding in your Tier-1 activation. Assess the resources on the construction site. Request additional resources needed during the brief incident report.
Brief Incident Report (B.I.R.) - A B.I.R. Is based on the intelligence gathered for the “Size up”.
Example: “Engine 1 is on the scene of a trench rescue. We have two live workers trapped by a cave in. The trench is 7 Ft. Deep and 4 Ft. Wide with “Compact Soil”. One wall has collapsed. No working utilities are on site. Engine 1 will begin command and initial actions.”
Trench Rescue Resource List ( Please use this as a template. Fill in contact names and numbers of local resources.)
4. SCENE MANAGEMENT AND SITE CONTROL First Responders (Awareness Training Level) are responsible for site control and scene management. Scene Management and Site Control are critical elements of successful rescue incidents .
Successful Scene Management at a trench rescue must include:
Incident Management System - Basic IMS practices are essential for scene management at trench incidents.
Command Post – A clearly defined and identifable Command Post is needed.
Staging Area - Develop an area that is capable of receiving all resources. Staff the staging area appropriately, for the size of the incident.
Standard Operating Guidelines (SOG) - First Responders are responsible for following standard operating guidelines.
SOG training is found in Operation level rescue courses.
Incident Action Plans (IAP) – Effective Scene Management includes and incident action plan (IAP) that consists of strategic goals, tactical objectives and resource assignments.
Establish operational zones (hot, warm and cold) with secure entry points.
Prepare the site for the arrival of incoming resources.
Minimum site control activities include the following:
5. HAZARD RECOGNITION There are a number of hazards associated with trench and excavation incidents. Awareness Level personnel must be trained to recognize these hazards. They must also be trained in procedures necessary to mitigate hazards within the general area. This “general area” is typically an area around the trench or excavation within 300 feet, or as determined by the Incident Commander.
An unprotected (see Protection Methods) trench is a hazardous environment. Collapse (or cave-in) occurs in a fraction of a second, often without warning. Workers in a trench during a cave-in are often seriously injured or killed. Suffocation, asphyxia, crush syndrome and impact related traumatic injuries are likely causes of trench fatalities.
Soil Properties :
Average weight: 100 lbs. per cubic foot – 2,700 lbs. per cubic yard.
Wet, compact, running: These characteristics will dictate how the soil will flow around and entrap/suffocate a victim.
HAZARD MITIGATION Mitigation methods used but are not limited to : CONTROL : Reduce the effect of hazards. Examples: - Vibrations: Shut down traffic and heavy equipment. - Impact Loading: Walking on ground pads or on the short wall end of the trench lip. - Egress: Place a ladder into the trench for egress of workers. - Liquid: Dike water or spilled fuel (if adequate PPE is available). REMOVE : Physically remove hazardous items, such as: - Trip hazards (string lines, tools on the lip) - Gasoline/fuel containers - Small pipes near the lip AVOIDANCE : Stay clear of the hazard (exclusion zones) - Identify hazards - Set-up zones to prohibit entry into hazardous areas. PROTECTION : Dress for the dance - PPE - Gloves - Helmet - Full body - Boots - Respiratory *****
6. Identify Collapse Patterns & Causes of Collapse First Responders must have an understanding and appreciation of the dynamics of trench/excavation collapse. Dynamic conditions which contribute to cave-ins are considered causes of collapse . Trenches generally collapse in similar ways, which we call patterns of collapse . Entry into trenches/excavations can be made safe by a variety of protection methods.
Spoil Pile Causes of Collapse Spoil piles that are not set back from the edge of the trench can slide into the trench. The weight of the spoil pile also creates an additional (Superimposed) load on the trench wall that can cause the wall to collapse. OSHA states that the pile must be a minimum of two (2) feet from the edge.
Causes of Collapse In addition to spoil piles, other superimposed loads can cause a trench wall to collapse. Common superimposed loads include pipes, excavators, loaders, trucks and construction equipment. Superimposed Loads
Vibration Causes of Collapse Vibrations created by motor vehicles, heavy equipment and near by trains can cause soil to begin to move. An object in motion wants to stay in motion. Vibrations can cause a trench to collapse.
Layered Soils Causes of Collapse Layered soil is subject to cave-ins. This is especially true when heavier (compact) soil is layered above lighter and more granular soil. Example: clay above sand.
Disturbed Soil Causes of Collapse Much like layered soil, previously disturbed and backfilled trenches have a high potential to collapse.
Causes of Collapse Water seeping into trench walls puts the soil in motion. Soil in motion is likely to cave in. Seeping water is likely caused by a broken water or sewer line, but can be caused by very rainy conditions. Excessive Water
Causes of Collapse Standing Water Standing water will undermine the bottom of the trench walls. This will cause the support (foundation) of the wall to erode away and allow the wall to cave in.
Fissures Top View Wall View Causes of Collapse Fissures Insufficient water causes the soil to crack. These cracks are called fissures. Fissures will expand until sections of the wall cave in. Top View Insufficient Water
Trench walls may be sloped to prevent cave-ins. A professional engineer must design the sloping angle provided:
The slope is not steeper than 1 ½ horizontal to 1 vertical
Tabulated data is used
Causes of Collapse All trenches five feet and deeper must be considered as high collapse potentials. OSHA states that no one may enter an open trench that is deeper than five (5 ft.) until protective methods have been provided Unprotected Trenches
There are four common patterns of trench collapse Collapse Patterns
Collapse Patterns Spoil Pile Collapse The excavated soil (spoil) is piled on the lip. This soil is loose and has a tendency to slide. If it is not placed far enough away from the lip it will slide into the trench and bury workers.
Collapse Patterns Wall Shear Collapse The collapse of an entire section of wall from lip to floor.
Collapse Patterns Lip Shear Collapse Lip slide collapses are similar to shear wall collapses, but on a smaller scale. A fracture occurs at the top of the trench and results in the breaking and sliding of the trench lip.
Slough-In Collapse Patterns A collapse that occurs near the bottom of the wall leaving the potential for the collapse of an overhanging ledge.
Protection Methods The following five Protection Methods are recognized by OSHA for underground construction work.
A method of protecting workers by excavating to form one, or a series of steps or “benches”.The first bench (at the floor) can be no more than 4 feet (vertical). Subsequent benches can be no more than 5’ vertical.
The vertical to horizontal ratio of the benches depends on:
Previous soil disturbances
X TRENCH SHIELD A pre-constructed set of side plates and adjustable cross members to prevent the walls of the pit from collapsing. A structure which is designed to withstand the forces being applied to it by moving soil and therefore “protect” employees within it. The bottom of the trench box must rest not more than 2’ from the floor. The top of the trench box should extend at least 18” above the lip.
Sheet Piling Sheet piling is a form of driven piling using thin interlocking sheets of steel to obtain a continuous barrier in the ground. The main application of sheet piles is in retaining walls and cofferdams erected to enable permanent works to proceed. Normally, vibrating hammers, t-cranes and crawler drilling are used to establish sheet piles.
Devices which are designed and installed to support trench walls and therefore prevent trench wall collapse.
Examples of “Shoring” are:
Aluminum or steel hydraulic shores
Pneumatic (air operated) shores
Screw Jacks (mechanical jacks)
7. Non-Entry Rescue Non-entry rescues include placing a ladder to allow a victim to perform a self-rescue or allowing uninjured persons in the trench to remove a victim.
The story below will give you some insight into how the events of a Non-Entry Trench Rescue occurs.
During the summer of 1995, while I was assigned to our technical rescue station, we responded to the scene of a large excavation for an incident involving an injured worker. After arrival, the first officer found a large excavation for a sewage pumping station that was under construction. While unloading steel panels , the crane operator swung the load over the trench and struck a worker in the head and upper body. The subsequent blow from the panel knocked the worker into the bottom of the excavation, and he landed on his back. Although he remained conscious, he did suffer a broken shoulder and head injuries. The first in company officer called me on the tactical channel. He advised all of us of the situation and communicated his risk benefit analysis. He then asked whether it was acceptable for the victim to use the ladder to self-evacuate if they could manage to get some sort of lifting device to assist. His main concerns at the time were considerations for patient packaging and not providing adequate cervical spine immobilization for a victim that had fallen that far. My response was, “Yes, if the victim can self-evacuate with your assistance, please allow him to do so.” Although the victim was suffering from possible head, shoulder and internal injuries, the speed of self-rescue far outweighed the need for additional considerations for patient care and packaging. The EMS officer on scene also had concerns about proper patient packaging; however, the company officer convinced him this was the best tactic. It was determined that EMS personnel's main concern was about causing further injury by allowing the patient to move on his own. When it was explained to him the time it would take to move forward with the modified self-evacuation rescue was determined the best manner in which to resolve the incident. A ladder was placed into the trench. As the victim slowly made his way up the ladder, the EMS crew prepared the backboard and other trauma-related medical supplies and waited for him at the top of the ladder. At that time, he successfully escaped his perilous situation and was packaged and transported to the emergency room for more definitive medical treatment. In this case the first arriving he and his firefighters had no “rescue” equipment and were armed only with knowledge. This knowledge gave them the awareness to properly assess the situation, determine that the best tactic was a non-entry rescue, recognize the type of excavation and its inherent dangers, evaluate the protective system and then have to relay the information to more knowledgeable personnel who were en route to the scene. The result was a successful “non-entry” rescue. Jonathan A. Rigolo, Captain Virginia Beach Fire Department Virginia Beach, Virginia Note: Other successful “non-entry rescues” involving cave-ins have included lowering a shovel to a partially buried victim. After digging themselves out, the victims were able to climb a ladder placed into the trench from the lip.
Appendix A Trench Rescue Operations Level Equipment List
(5) Fire service ladders (24’ extension/ 14’ roof)