Trench and Structural Collapse Rescue Program

A cubic metre of soil weighs about as much as a car, and a trench that has collapsed once is more likely, not less, to collapse again. The people who die in trench rescues are often the rescuers: co-workers, bystanders and responders who went in to dig out a visible victim before the trench was made safe (NIOSH, n.d.-b). Structural collapse adds the same lesson at a larger scale, with secondary collapse, live utilities and void spaces that look survivable and are not. This program is working when no member of the department enters an unprotected trench deeper than the regulated depth for any reason, including to reach a victim; when the department has declared the level of trench and collapse rescue it provides and can field it with the shoring, monitoring and people it needs; when a collapse zone is set and kept at every structural collapse and every defensive fire; when the department knows which engineer it will call and when; and when every trench and collapse response ends with a review.

Conditional unless the department provides trench or structural collapse rescue above awareness; it answers Profile Worksheet question 16 (01 Program Profile Worksheet). Awareness-level elements (5.1, 5.2, the recognition and deny-entry rules, the collapse zone rule in 5.8) apply to every department, because every department will arrive first at a trench collapse or a building collapse in its district whether or not it has adopted the service. Departments with urban search and rescue (USAR) or heavy urban search and rescue (HUSAR) obligations extend section 5.8 with their task force procedures.

Consistent with 06 Glossary and Acronyms.

• Collapse zone. The area around a structure, at least the height of the structure and generally one and a half times it, inside which no one operates when collapse is possible.
• Excavation. Any cut, cavity, trench or depression in the earth formed by removing material.
• Protective system. Shoring, bracing, sloping, benching or a trench cage that protects a person in an excavation from collapse.
• Secondary collapse. Further movement of soil or structure after the initial collapse, often triggered by rescue activity, vibration, water or load.
• Shoring. A structure of timber, pneumatic or hydraulic struts and panels that supports the walls of an excavation or a damaged building element.
• Spoil pile. The excavated material placed beside the trench.
• Trench. An excavation whose depth exceeds its width (the definition most provinces use; J18 Excavation and Trench).
• Trench cage (trench box). An engineer-certified steel or aluminum structure placed in a trench to protect workers from wall collapse.
• Void. A space within collapsed material that may hold a survivable position.
• Psychological safety. The shared belief within a crew that it is safe to speak up, ask, admit error and challenge (Edmondson, 1999)DOI.

The core is generic. The depth trigger, slope rule, ladder distance, spoil distance, atmospheric rule and engineer triggers come from the applicable excavation regulation and differ by province and territory (J18 Excavation and Trench). Most provinces have no firefighter exemption for excavations: a rescue entry into a collapsed trench is work in an excavation, and the protective system the department installs is judged against the excavation rules.

Deltas from 01 Roles and Responsibilities: an on-call structural engineer ({{Structural Engineer (on call)}}) is a standing consultant to the Technical Rescue team; public works provides excavation equipment, utility locates and site knowledge under a written arrangement.

Requirement. The department declares, separately for trench rescue and for structural collapse rescue, which level it provides (NFPA 2500, 2022): awareness (recognize, isolate, deny entry, call for resources, non-entry rescue of a lightly trapped person who can free themselves with a reach); operations (trench: install commercially manufactured protective systems in straight trenches to the manufacturer’s tables and conduct rescue inside them; collapse: light-frame and ordinary construction with basic shoring and surface and void search); technician (trench: intersecting and deep trenches, engineered systems; collapse: heavy construction, breaching, lifting, advanced shoring). Where the department is below technician, it names the mutual aid, provincial USAR or HUSAR capability it will call, with the call-out route and the expected time. Most municipal departments are operations for trench and awareness or operations for collapse; declaring more on paper than the roster can staff is the recurring failure pattern. Evidence. The signed declaration; the capability matrix (17.5). Stage. S1.

Requirement. Every member knows the numbers that decide whether a trench can be entered, and the numbers are in the procedure, not in someone’s head.

Minimum method. The generic rules; each province’s and territory’s values are on J18 Excavation and Trench:

• Depth trigger. A trench deeper than the depth your jurisdiction sets (commonly 1.2 m; 1.4 m or 1.5 m in a few) is not entered unless a protective system is in place, the walls are sloped to your jurisdiction’s rule, or the trench is in sound stable rock. There is no rescue exception: the victim is reached by making the trench safe from outside first.
• Wall-height rule. Nobody stands or works within a horizontal distance equal to the wall height of an unprotected wall, including on the lip.
• Engineer triggers. An engineer’s written design or certification is required before entry where the trench is deeper than the depth at which your jurisdiction requires an engineered design (6 m in several jurisdictions, 3 m to 4.5 m in others, and some require an engineer for all shoring; J18 Excavation and Trench), where trenches intersect, where there are adjacent structures or utilities whose support is affected, where the soil has been previously disturbed, where sloping steeper than your jurisdiction’s rule is proposed, or where the shoring is not a commercially manufactured system installed to its tables. The on-call engineer is reached through dispatch.
• Soil assessment is done by the rescue team lead using the training conventions (cohesive, granular, previously disturbed; layered; wet; vibration present) to choose the protective system and spacing from the manufacturer’s tabulated data. A soil that “looks stable” is treated as unstable; previously disturbed soil (every trench a backhoe just dug) is the worst case.

Evidence. The procedure; the trench size-up checklist (17.1) completed at every incident and drill. Stage. S1.

Requirement. Trench rescue is run as a controlled, sequenced operation under SWP - Trench Rescue: make the trench safe, then make the rescue.

Minimum method.

1. Scene control. Stop every engine, compressor and vehicle within the exclusion distance (this program’s default is 15 m or more; confirm locally) to remove vibration; move apparatus back; one way in and out; the public, the contractor’s crew and distraught co-workers kept back; a safety officer assigned.
2. Utilities. Assume every line in the trench is live and charged; isolate with the utility or the contractor; no entry over an unisolated gas line.
3. Atmosphere. Test before entry and continuously wherever sewer, fuel, decomposing material, engine exhaust or oxygen-displacing gas may exist, as Confined Space Program section 5.7 sets out; ventilate; no entry above the department’s action level.
4. Spoil and surface loads. Spoil pile and every other load kept back the distance your jurisdiction sets from the lip (0.6 m to 1.2 m, depending on the jurisdiction); spoil that cannot be moved is cut back; ground pads laid around the lip to spread load and protect the edge.
5. Protective system. Panels and shores installed from outside the trench, top down, to the manufacturer’s tabulated data for the soil and depth, in the order the procedure sets (the trench is never entered to place the first shore); supplemental shoring where the victim’s position needs it; de-shoring bottom up after the rescue.
6. Ladders. A ladder in the protected zone, extending above the top, within the distance your jurisdiction sets of every member in the trench (commonly 8 m or 15 m, and as little as 3 m), and a second ladder where the work area is long.
7. Victim access and packaging. Dig by hand and with vacuum or air tools around the victim; no mechanical digging within reach of the victim; protect the victim’s airway and body from further spoil; medical care in the trench by a member who is also protected; packaging for vertical lift.
8. Secondary collapse watch. A member assigned to watch the walls, the spoil and the adjacent ground, with the authority to order everyone out.
9. Engineer called at any trigger in 5.2.
10. Recovery decisions. Where the victim is clearly deceased, the operation changes to a recovery with no acceptance of risk to members; the incident commander records the decision and its time.

Evidence. The procedure; incident records with the checklist; post-incident reviews. Stage. S1 at the declared level.

Requirement. The department carries, inspects and tests the shoring it needs for its declared level, and every item is traceable.

Minimum method. A shoring equipment inventory (17.2) with each pneumatic or hydraulic strut by serial number, its rated range, its last manufacturer inspection and pressure test, its relief valve test; panels and sheeting by ID and condition; timber (grade stamped, stored dry, inspected before use, replaced when split or weathered); ground pads, cribbing, wedges; air supply (cylinders, regulators, hoses) inspected like SCBA air; vacuum and air-knife tools; trench cages, if carried, with the engineer’s nameplate and depth limit and a daily inspection record whenever in use. Annual manufacturer inspection and pressure test of pneumatic and hydraulic shores; monthly visual inspection of everything; post-use inspection and log. Manufacturer tabulated data carried on the rescue unit and used, never memory. Evidence. The inventory and inspection log; manufacturer certificates. Stage. S1 at operations.

Requirement. The department has a named on-call structural or geotechnical engineer ({{Structural Engineer (on call)}}) with a written arrangement (hours, contact route, fee basis, liability and insurance, what the engineer will and will not certify at a scene) and triggers for calling. The engineer is consulted in designing the department’s own trench training site, reviewing the shoring inventory’s tabulated data, and planning for collapse incidents. Evidence. The arrangement; call records. Stage. S1 for the arrangement; the department does not declare operations in trench without it.

Requirement. Trench and collapse incidents need resources the department does not own. Minimum method. Written arrangements with public works (excavators, operators, dewatering pumps, lighting, utility locates), the utilities (gas, electrical, water, telecommunications isolation), the municipality’s building official, local excavation and shoring contractors (equipment and tabulated data), the regional USAR or HUSAR task force, the provincial regulator’s notification route for a workplace collapse, and the coroner or medical examiner for recovery operations. A contact list on the rescue unit and in dispatch, reviewed every six months. Evidence. The arrangements; the contact list and its review date. Stage. S1.

Requirement. Structural collapse response is run at the declared level under written procedure with these controls, whatever the level:

• Collapse zones set on arrival around every damaged structure and every exposure structure that could fail, held with tape, lights and a monitor, and expanded when conditions change. The collapse zone rule applies equally at defensive structure fires and is the single control that answers the collapse pattern in line-of-duty death investigations (NIOSH, 2003b, F2002-07).
• Size-up of construction type, occupancy, collapse pattern (lean-to, V, pancake, cantilever, A-frame), utilities, hazardous materials, secondary collapse indicators, weather and time.
• Utilities assumed live until the utility confirms isolation.
• Building marking with a structure and hazard marking system the department adopts and trains (the national USAR and international search and rescue systems are the common conventions), applied at every entry point and kept current, so that every crew and every arriving task force reads the same marks.
• Void search only by trained members, with shoring ahead of the search, atmospheric monitoring, accountability at the entry point, communication, a safety officer watching for secondary collapse, and a rescue plan for the searchers; no freelancing into voids.
• Monitoring for secondary collapse by a dedicated member or instruments (transits, crack monitors) with an evacuation signal every member knows.
• Heavy equipment coordinated by one person with a spotter, never working where members are inside.
• Engineer called at every collapse where members will enter or work beneath damaged elements.
• USAR and HUSAR interface. The department’s role before the task force arrives (size-up, zones, marking, utilities, surface rescue, staging, accountability) and after (support, logistics, integration into the task force’s structure) written into the procedure and exercised with the task force.
• Accountability and rehab as Emergency Operations Safety Program and Firefighter Rehabilitation Program require; collapse incidents run for days and fatigue is a collapse risk.
• Respiratory protection for dust (P100 at minimum; SCBA where the atmosphere is unknown) and decontamination after, under Decontamination and Contamination Control Program.

Evidence. The procedure; the collapse safety checklist (17.3); exercise records with the task force. Stage. S1 for zones, size-up, utilities, marking and the no-freelancing rule; S2 for void search and shoring at operations.

Requirement. Because structural collapse kills firefighters at ordinary structure fires, not only at collapse incidents, the collapse zone rule in 5.7 is written into Emergency Operations Safety Program and applied at every defensive fire and every fire in a building showing collapse indicators, with the incident safety officer assigned early. This program owns the rule’s content; the operations program owns its application. Stage. S1.

(a) Work-as-done. Before the trench or collapse procedure is written or changed, the learning team describes with the crews: what the first-arriving engine actually does at a trench collapse with a contractor’s crew already digging and a victim talking; who stops the digging and how that conversation goes; how long it really takes the rescue unit to arrive and set the first panel, with the people who normally staff it; how the collapse zone is held at a defensive fire when the hydrant is inside it; how building marking is done now, if at all; what the crews do with an engineer’s advice they do not understand; and where they have improvised shoring in the past.

(b) Capacity and margins. This work goes right because the first officer holds the scene and does not let anyone in, because the rescue unit arrives with the right panels and the tabulated data, because the shores are tested and the air works, and because somebody watches the walls. The margin erodes with a visible, conscious victim and a family or co-workers already in the trench; with vibration from traffic and equipment nobody stopped; with rain, frost and thaw; with daytime volunteer response that puts the rescue unit 40 minutes out; with collapse incidents that run through the night; and with task forces that arrive to a scene nobody marked. The program protects the margin by making “make it safe, then make the rescue” the only sequence, by staffing a secondary collapse watch, by building the engineer and public works into dispatch, and by declaring only the level the roster can field.

(c) Just culture. A member who went to the edge of an unprotected trench to talk to the victim, or who started to dig because the victim asked, was answering a human pull every rescuer feels; the review asks what would have made holding back easier, not who to blame. The learning firewall applies to every debrief, learning team, near-miss report and review. Conduct concerns go to a separate process run by different people (Incident Investigation and Learning Program; The Human Factor, 2026a).

(d) Psychological safety. Anyone at a trench or collapse can say the hazard and the action: “Stop, everybody off the lip, the wall is moving.” The rescue group supervisor and the incident commander acknowledge, hold, and review it later. Members are expected to question the soil call, the shore spacing, the collapse zone size, or an order to enter a void; officers answer with the reason or change the plan. Leaders show it is safe by rehearsing the evacuation signal in every drill, by thanking the member who held the scene in the hot debrief, and by reporting their own near misses. A member’s concern about this program (a shore that leaked, a drill site that felt unsafe, a declaration the station cannot staff) goes to the company officer, the rescue team lead, the JOHSC consultant or the near-miss system and gets an answer within 15 days (section 12).

(e) Learning link. Every trench and collapse response, every annual soil evolution and every collapse zone set at a fire gets a Tier 1 After-Action Review. Any member entry into an unprotected trench, any secondary collapse with members inside the zone, any shoring failure, and any near miss with potential for death goes to Tier 2 Post-Incident Analysis. A death or critical injury is Tier 3 Independent Learning Review (The Human Factor, 2026a). Crew AAR questions: What did the victim and the people on site ask us to do, and what did we do first? When did we know the soil and the utilities, and how? What would have made it easier to hold everyone out until the first panel was in? Full method: Incident Investigation and Learning Program and Manual 02 - The Three Tiers and Event Triage.

Training entries into any excavation on a training site follow the full excavation rules: the training trench is a workplace, and the exemption question does not arise.

• SWP - Trench Rescue
• SWP - Confined Space Entry and Rescue (owned by Confined Space Program; atmosphere and attendant rules)
• SWP - Rope Rescue Systems Rigging and Inspection (owned by Rope Rescue Program; vertical lift)
• The collapse zone content in the structural firefighting procedures of Emergency Operations Safety Program

• Trench rescue size-up and safety checklist (17.1); shoring equipment inventory and inspection log (17.2); collapse incident safety checklist (17.3); engineer and partner arrangements register (17.4); capability matrix (17.5); training and competency sign-off (17.6); quarterly indicator worksheet (17.7)
• Retention: incident records and checklists for the period in 05 Document Control and Records and longer for any incident with injury; shoring certificates for the life of the item; training records for the member’s service plus the period in the records note.

Loop test. A rescue team member reports on Monday that two pneumatic shores leaked down during Saturday’s drill and the relief valves have never been tested. By Friday both shores are tagged out, the item is in the register with the rescue team lead as owner, and the member has heard back. Within 30 days every shore has had its manufacturer inspection booked or completed, the inventory shows a test date for each, the inspection procedure adds the relief valve check, the change notice goes to every station that carries shores, and the quarterly update reports it closed with the test currency indicator attached.

Checklist: Checklist - Confined Space, Trench and Rope Rescue. The five questions first:

1. Show me the separate declarations for trench and collapse, and the mutual aid route for whatever you do not provide.
2. Show me the record of last year’s evolution in real soil and who attended.
3. Pick a shore: show me its last manufacturer test and this month’s inspection.
4. Who is your on-call engineer, when did dispatch last test the contact, and when did you last call them?
5. Show me the last defensive fire’s ISO log: where was the collapse zone, and who held it? And when did a member last call everyone off a lip, and what happened to them?

Accreditation crosswalk. The declarations, capability matrix and annual appraisal evidence the technical rescue criterion; the hazard reporting and corrective action records evidence the occupational health and safety criterion (CPSE, 2019, criteria 5G.1, 5G.2, 11A.2, 11A.3).

Generic patterns from trench and collapse fatality investigations (NIOSH, n.d.-b; NIOSH, 2003b, F2002-07) this program answers:

• Civilian and responder entry into unprotected trenches to reach a victim; secondary collapse kills the rescuers. Controlled by 5.2 and 5.3 (no entry; protective system from outside first).
• Spoil pile and apparatus too close to the lip; vibration from idling engines. Controlled by 5.3 steps 1 and 4.
• “Clay that looks stable” and previously disturbed soil treated as safe. Controlled by 5.2 soil assessment rules.
• No atmospheric monitoring in trenches with sewer or fuel exposure. Controlled by 5.3 step 3.
• Structural collapse: freelancing into voids, no accountability, no engineer, no collapse zone for an uninvolved exposure structure; the investigation recommended establishing and monitoring a collapse zone and appointing an independent safety officer early (NIOSH, 2003b, F2002-07). Controlled by 5.7 and 5.8.
• Task outside trained scope (the recurring Canadian theme in 05 Design Principles and Lessons Learned). Controlled by 5.1 and the capacity indicator.

Stage 1 minimum. Both declarations (5.1); the triggers and thresholds in the procedure (5.2); awareness training for every member; the collapse zone rule in operations (5.8); the engineer arrangement and the partner list (5.5, 5.6); if operations is declared for trench: the procedure (5.3), the shoring inventory with tested shores (5.4), the annual evolution (7); one learning-team session on the first ten minutes at a trench; the accountability loop (12).

Cost note. People: program manager and team about four hours a month; a half-day quarterly drill and one full-day annual evolution for the team; a custodian for the shoring inventory. Money: a trench operations cache (panels, strongbacks, pneumatic shores with air, ground pads, hand and vacuum tools) is a five-figure purchase plus annual manufacturer testing; the engineer’s retainer; the annual evolution site (often donated by public works or a contractor). Awareness-only departments need training, a size-up checklist and the mutual aid route.

This chapter relies on the following legal requirements, which differ by province and territory. Check your jurisdiction’s section on each topic page before adopting it.

Completed by the first officer and the rescue group supervisor; kept with the incident record.

National Institute for Occupational Safety and Health [NIOSH]. (n.d.-b). Fire Fighter Fatality Investigation and Prevention Program [Program website and investigation reports]. Centers for Disease Control and Prevention. https://www.cdc.gov/niosh/firefighters/fffipp/index.html

Occupational Safety and Health Administration [OSHA]. (n.d.-b). Excavations: Soil classification (29 C.F.R. Part 1926, Subpart P, Appendix A). U.S. Department of Labor. https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926SubpartPAppA