11 Pre Dig Planning Tips for Trenching, Utilities, Permits, and Emergency Response

Pre dig planning is where trenching incidents are prevented. A trench collapse, utility strike, flooding event, or poorly coordinated emergency response can happen fast, often before protective systems are installed or before anyone realizes conditions have changed. OSHA’s excavation standard, 29 CFR 1926 Subpart P, places heavy emphasis on competent person oversight, soil and protective system decisions, inspections, and safe access and egress. But good outcomes start earlier, with planning steps that happen before the first bucket goes in the ground.

This list gives 11 practical pre dig planning tips you can use for trenching and excavations involving utilities, permits, and emergency response. Each tip is written for field use by foremen, supervisors, estimators, and OSHA Competent Persons, including Arizona contractors working in hot, dry soils that can still become unstable quickly after water releases, rain, or adjacent vibration.

• 1) Define the excavation scope, limits, and sequence before mobilizing

  Many trenching failures start with a vague scope. “Dig a trench from point A to point B” is not enough. Pre dig planning should define where the trench starts and stops, expected depth range, the purpose of the excavation, and how the work will be sequenced. Sequencing matters because the safest protective system or access plan for one segment may not work for another segment with different depth, soil, or congestion.

  Build a simple work plan that answers these questions in writing and review it with the crew:

  • What is the trench for, sewer, water, storm, electrical, gas, communications, or tie in work?
  • What is the expected alignment, width, and target depth?
  • Will the work be open cut, bore and pit, potholing, or a mix?
  • What is the planned daily production goal and how will the trench be protected at the end of each shift?
  • What equipment will be used and where will it travel, excavator size, trench box delivery, vacuum excavation, pumps, and compactors?
  As part of scope, decide whether trench exposure is truly necessary. Consider reroutes, aboveground temporary bypass, directional boring, or using existing access points. If the excavation must happen, decide early whether the plan assumes sloping, benching, shielding, or shoring. Waiting until the trench is already open is a recipe for rushed decisions.

• 2) Identify and empower the OSHA Competent Person for each shift and location

  OSHA requires a competent person for excavation work. That role needs to be assigned by name, not by title, and it needs authority. The competent person must be able to stop work, require protective systems, order atmospheric testing when needed, and correct hazards immediately. Planning should include who the competent person is, who is the backup, and how the role is transferred if crews split or shifts change.

  Pre dig planning items to confirm:

  • Who is the competent person on site, and what training and experience qualifies them for trenching decisions?
  • Who performs daily and as needed inspections, including after rainstorms, water releases, or any hazard increasing occurrence?
  • Who has authority to revise the protective system plan when depth, soil, or adjacent loading changes?
  • How will the competent person document inspections, soil classification, and corrective actions?
  In Arizona, dry conditions can hide instability. Caliche layers, loose sand pockets, backfill zones, and utility corridors can produce Type C behavior even when the surface looks firm. Competent person decisions should not be based on appearance alone. Plan for soil evaluation tools and methods, including visual and manual tests, and ensure the competent person can interpret the results and adjust the protection plan accordingly.

• 3) Start utility research early, then confirm with locating, potholing, and field verification

  Utility strikes are among the highest consequence excavation events. Pre dig planning should use a layered approach. Paper records alone are not reliable. Locates alone are not enough. The goal is to develop a verified picture of what is in the ground, where it is, how deep it is, and how it is protected.

  Build your utility plan using multiple sources:

  • As builts, GIS maps, and utility company drawings, knowing they can be outdated.
  • Site walks to identify surface clues, pedestals, valves, meters, pull boxes, markers, and patchwork in pavement.
  • One call notification, in Arizona this is typically Arizona 811, and any municipal locate requirements.
  • Private utility locating for facilities not covered by one call, such as private electric, campus systems, irrigation, and site lighting.
  • Potholing or daylighting using vacuum excavation or careful hand tools to verify location and depth before full trenching.
  Include potholing in the schedule and budget. It is often the cheapest risk reduction step you can take. Plan for how potholes will be protected, backfilled, and documented. Require the crew to stop if unmarked lines are found, if marks are missing in a work zone, or if a locate ticket is expired. Also plan for the effect of utilities on protective systems. A trench box may not fit around congested lines, and shoring may need special placement to avoid damaging conduits or clay pipe.

• 4) Confirm permitting, jurisdictional rules, and notification requirements before you dig

  Permits are not just a paperwork step. They define conditions, inspections, traffic control requirements, and sometimes restrictions on excavation methods near critical infrastructure. Planning should identify every jurisdiction involved, such as city, county, state right of way, tribal land, federal land, or special districts. Each may have different rules for trenching, dewatering discharge, spoil placement, and restoration.

  Common permits and approvals to confirm:

  • Right of way or lane closure permits, including allowed work hours and detours.
  • Excavation permits required by the property owner or facility manager.
  • Stormwater pollution prevention requirements and dust control rules.
  • Dewatering discharge approvals, including where pumped water may go.
  • Hot work permits if cutting, welding, or thermal tools are used near utilities.
  • Railroad or airport authority requirements when working near controlled areas.
  Also plan for required inspections. Some permits require inspection of bedding, pipe placement, or backfill compaction before covering. Coordinate these inspections so the trench is not left open longer than necessary. If work involves gas utilities, high voltage, or critical communications, confirm whether utility representatives must be present for excavation near their facilities and schedule them early.

• 5) Perform a site hazard survey for access, adjacent loads, and changing conditions

  A trench is influenced by everything around it. Pre dig planning should include a walkdown and hazard survey focused on conditions that increase collapse risk or complicate rescue. Document what you find and decide how controls will be implemented.

  Key hazards to evaluate:

  • Adjacent structures, walls, foundations, sidewalks, and slabs that could impose surcharge loads or be undermined.
  • Roadways, heavy equipment travel paths, and vibration sources such as compactors, pile drivers, and traffic.
  • Stockpile and spoil placement locations, keeping spoil at least 2 feet back from the edge and considering more distance where sloughing is likely.
  • Surface water and drainage paths, including irrigation, downspouts, and low points where runoff collects.
  • Overhead hazards, power lines, and required clearances for excavators and box delivery trucks.
  • Ingress and egress for workers and emergency responders.
  Plan for housekeeping and the work zone footprint. Tight sites often cause crews to stage materials right at the edge. If the site is tight, solve it in planning by designating laydown areas, scheduling material deliveries, and using smaller equipment where necessary. Include plans for fencing, barricades, and fall protection around open excavations when the public, other trades, or nighttime exposure is possible.

• 6) Establish soil classification assumptions, but verify in the field and plan for worst case

  Soil classification drives protective system requirements. A common planning error is assuming the soil will be stable because it has “always been fine here” or because the surface looks hard. OSHA recognizes Type A, Type B, and Type C, and the most conservative choice is Type C. In practice, disturbed soil, backfill zones, and wet or seeping soil often behave as Type C.

  Pre dig planning should include:

  • Anticipated soil types based on local geology and past projects, while still requiring field verification.
  • Expectations for disturbed ground, especially in utility corridors and near previous excavations.
  • Tools and methods for classification, including visual analysis, plasticity, and thumb penetration, plus awareness of layered soils.
  • Decision triggers for switching protection methods if soil conditions change.
  Plan for the worst case protective system you might need. For example, if the trench may reach 8 feet in Type C soil, plan for sloping that may require a large footprint, or plan for shielding or shoring to reduce the footprint. If the site cannot accommodate the slope, do not rely on “we will figure it out.” Arrange for trench boxes, hydraulic shoring, or other systems ahead of time. Also plan for access and egress requirements, such as ladders within 25 feet of lateral travel and extending at least 3 feet above the landing.

• 7) Choose protective systems and tabulated data before excavation, including special cases

  Protective systems should be selected before the trench is open. This includes matching the system to depth, soil type, trench width, utility congestion, and the need for workers to enter. If workers will enter, protection is not optional, except where OSHA allows short duration exposures in shallow excavations and only when no cave in hazard exists. In practice, treat entry as requiring a protective system.

  Planning should cover:

  • Whether you will use sloping, benching, shoring, shielding, or a combination.
  • Trench box dimensions, including inside width, height, and spreader placement relative to utilities.
  • Manufacturer tabulated data on site, including allowable depth, soil conditions, and installation requirements.
  • Installation plan, including how the box will be set, how workers will stay out of the trench during placement, and how it will be advanced.
  • End protection, transitions, and how you will handle intersecting trenches and bell holes.
  Special cases should be decided ahead of time. Examples include crossing existing utilities, making connections in bell holes, installing manholes, working near foundations, and excavating in pavement where saw cuts can create unstable edges. Plan for how the protective system will be maintained when the trench changes shape. If the work requires workers to be outside the shield, plan for engineered shoring or a redesign of the approach.

• 8) Plan water control and dewatering as a core safety system, not an afterthought

  Water changes everything. Even small amounts of seepage can turn stable looking trench walls into flowing material, especially in sands and disturbed backfill. Water also creates slip hazards, can undermine ladders, and can hide voids. Pre dig planning should treat water control as part of the protective system.

  Items to plan and verify:

  • Known groundwater levels, seasonal changes, and history of perched water in the area.
  • Nearby water sources, irrigation lines, fire hydrants, canals, retention basins, and storm drains.
  • Rain plan, including what triggers shutdown, how runoff will be diverted, and who monitors weather.
  • Dewatering method, such as well points, sump pumps, eductors, or trench dams, and how it will be installed without exposing workers.
  • Discharge location and permits, ensuring pumped water does not damage property or create traffic hazards.
  Include contingencies for sudden releases. Utility strikes can create flooding, and water main failures can fill an excavation quickly. Make sure the crew knows escape routes, ladder placement, and who contacts the utility owner in a water emergency. Plan for keeping electrical equipment away from standing water and for using ground fault protection as required. Also plan for erosion and undermining around the trench, particularly where pumped water is discharged.

• 9) Build a traffic control and public protection plan that matches real conditions

  Trenching frequently occurs in rights of way, parking lots, and along sidewalks. Traffic and public exposure add hazards including vehicle intrusion, vibrations that affect trench stability, limited staging space, and increased consequences if a collapse occurs near the public. Planning should use approved traffic control procedures and should consider the daily changes of traffic volumes.

  Pre dig planning steps for traffic and public safety:

  • Determine whether the site is on a state route, city street, or private property and apply the correct standards.
  • Define taper lengths, buffer spaces, and sign placement based on speed and lane configuration.
  • Decide whether flaggers are needed and verify their training and positioning.
  • Plan pedestrian routes, including ADA compliant detours where sidewalks are affected.
  • Control trench access with fencing, barricades, and covers where feasible.
  Also consider how traffic control affects trench safety. Cones placed too close to the edge can encourage vehicles to ride near the excavation. A better plan may require a full lane closure or barrier systems. Include a delivery plan for trench boxes and materials so trucks are not backing unpredictably in traffic zones. At night or low visibility, plan lighting that does not create glare for drivers and does not create shadowed areas where hazards are hidden.

• 10) Address atmospheric hazards, confined space triggers, and hazardous energy early

  Many crews do not think of trenches as atmospheric hazards, but they can be. Trenches can collect heavier than air gases, vapors from fuel spills, methane from decaying organic material, or gases from damaged utilities. OSHA requires testing where oxygen deficiency or hazardous atmospheres could reasonably be expected, including near landfills, sewers, chemical pipelines, or where welding and cutting occurs.

  Pre dig planning should include:

  • Assessment of nearby sources, sewers, storm drains, landfills, gas lines, industrial facilities, and contaminated soils.
  • Whether any part of the excavation could meet confined space criteria, especially pits, manholes, vaults, or deep narrow excavations with limited airflow.
  • Gas detection equipment availability, calibration status, bump tests, and who is trained to use it.
  • Ventilation plan if needed, including placement to avoid pushing contaminants into worker breathing zones.
  • Hazardous energy controls, including utility shutdown coordination, lockout where applicable, and verification of de energized conditions for electric lines.
  If the work involves tie ins to existing systems, plan for isolation. For example, water and sewer bypass operations can create hazardous atmospheres and biological hazards. Include PPE decisions, hygiene practices, and decontamination needs. If there is any chance of entering a space that qualifies as a permit required confined space, coordinate your confined space program and rescue plan with the excavation plan, rather than treating them as separate documents.

• 11) Create a trench emergency response plan that is specific, practiced, and rescue realistic

  Emergency response planning is not just “call 911.” Trench collapses can trap workers in seconds. Unplanned rescue attempts often create additional victims. Pre dig planning should define how you will prevent emergencies, how you will communicate, and what you will do in the first minutes if something goes wrong. The plan must match the actual site conditions, including access, address information, and response times.

  Include these elements in a trench emergency response plan:

  • Exact site location information for responders, street address, cross streets, nearest gate, and GPS coordinates if remote.
  • Who calls 911, who meets responders, and who controls site access.
  • Utility emergency contacts, including gas, electric, water, and communications owners.
  • Medical response planning for heat illness, dehydration, and trauma, especially for Arizona summer conditions.
  • Rescue policy that prohibits unprotected entry into an unstable trench and requires stabilization before rescue.
  • Equipment staging for emergencies, ladders, lighting, backboards, first aid kits, and means to shut down equipment.
  Plan the rescue reality. If a collapse occurs, rescuers need space to work, and they need to stabilize the excavation, often with shoring, trench panels, or specialized rescue systems. Coordinate in advance with local fire departments if possible to understand their trench rescue capabilities and response expectations. Practice communications and roles with your crew so everyone knows what to do, including stopping equipment, shutting off ignition sources, and accounting for personnel.

  Finally, document and review. Keep your planning notes, permits, locate tickets, soil classification records, tabulated data, inspection logs, and emergency contacts together in a field packet. A well organized packet helps the competent person make safer decisions and helps the crew stay aligned. If you want structured help building competent person level trench planning and field controls aligned with 29 CFR 1926 Subpart P, TheSafetyResource.com provides OSHA Competent Person trench safety training for Arizona contractors, on site or virtual, with hands on instruction. You can also call 602 359 6682 to discuss scheduling and site specific support.

Using these 11 pre dig planning tips as a repeatable checklist will reduce last minute improvisation. When the scope is clear, utilities are verified, permits and traffic control are coordinated, protective systems are selected ahead of time, and emergency response is realistic, trenching becomes a controlled operation instead of a gamble. Make pre dig planning a required step for every trench, every day, and treat changes in conditions as a trigger to pause, reassess, and adjust.