Excavation Activity Hazard Analysis
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Excavation and trenching operations on USACE and Department of Defense construction projects require an Activity Hazard Analysis (AHA) that meets the documentation and risk assessment standards of EM 385-1-1. Unlike a general JSA, the AHA must include a formal Risk Assessment Code (RAC) for each work step, identify the Definable Feature of Work (DFOW) being addressed, reference specific EM 385-1-1 sections, and designate competent persons by name and qualification before any ground disturbance begins. The AHA is submitted to the government Quality Control representative and must be accepted before the activity can proceed.
Excavation remains one of the highest-hazard activities in construction. OSHA reports an average of 40 trench-collapse fatalities per year in the United States, and USACE project sites are not immune to these incidents. EM 385-1-1 Section 25 imposes requirements that exceed general industry OSHA standards in several areas: all excavations 4 feet or deeper require protective systems (compared to OSHA's 5-foot threshold), daily competent person inspections are mandatory regardless of depth, and the contractor must maintain a written excavation plan that addresses soil classification, protective system design, utility location, dewatering, and emergency rescue procedures. The AHA serves as the operational document that ties these requirements to specific work steps and assigns accountability.
Ground conditions on military installations and federal construction sites frequently present complications not found on typical commercial projects. Decades of previous construction may have left unmarked utilities, buried debris, contaminated soil, or unknown underground structures. Many installations have restricted areas where utility records are classified or incomplete. The excavation AHA must account for these site-specific conditions and establish protocols for unexpected discoveries, including potential ordnance encounters on installations with active or historical ranges. Each work step in the AHA carries a pre-control and post-control RAC rating that demonstrates the contractor has systematically reduced risk from unacceptable levels to acceptable residual risk through engineered and administrative controls.
Disclaimer
This content is provided for general informational and educational purposes only. It is not a substitute for a site-specific Job Safety Analysis conducted by a qualified safety professional familiar with your workplace conditions, equipment, and personnel. OSHA citations, BLS statistics, and hazard controls referenced here may not reflect the most current standards or apply to your specific situation. Always consult current OSHA regulations, manufacturer guidelines, and a competent person before beginning work. Health & Safety Systems LLC assumes no liability for actions taken based on this content.
Definable Feature of Work (DFOW)
Excavation & Trenching
All open-cut excavation, trenching, and backfill operations including site preparation, utility exposure, foundation excavation, and pipe trench work. This DFOW covers soil disturbance from initial ground-breaking through final compacted backfill and grade restoration.
Typical Duration: 1-6 weeks
EM 385-1-1 References
Section 25.A: General Excavation Requirements
Establishes excavation planning requirements, competent person designation, and the requirement for protective systems at 4 feet or greater depth.
Section 25.B: Soil Classification
Requires visual and manual soil testing by a competent person to classify soil as Type A, B, or C before selecting protective systems.
Section 25.C: Protective Systems
Specifies sloping, benching, shoring, and shielding requirements based on soil classification and excavation depth.
Section 25.D: Trenching Operations
Covers trench-specific requirements including egress, spoil placement, water accumulation, and adjacent structure protection.
Section 01.A.13: Activity Hazard Analysis Requirements
Defines the AHA format, content requirements, review process, and the requirement that AHAs be accepted before work begins on each DFOW.
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Start Free TrialRisk Assessment Code (RAC)
The RAC matrix combines hazard severity and probability to assign a risk level before and after controls are applied. This AHA demonstrates risk reduction from initial to residual conditions.
Initial Risk (Before Controls)
High (2)
Severity: Critical | Probability: Likely
Residual Risk (After Controls)
Low (5)
Severity: Marginal | Probability: Seldom
Step-by-Step AHA Breakdown
Step 1: Review excavation plan and AHA with crew
Hazards
- Incomplete hazard communication
- Workers unaware of site-specific conditions
- Failure to identify underground hazards
Controls
- Conduct pre-task safety briefing covering AHA, excavation plan, and emergency procedures
- Verify all crew members sign the AHA acknowledgment
- Review site-specific geotechnical data and utility locate markings
Step 2: Utility locates and potholing
Hazards
- Struck underground electrical line
- Ruptured gas main
- Damaged water or sewer line
- Unmarked or mismarked utilities
Controls
- Verify 811 locate request completed minimum 48 hours prior
- Pothole (daylight) all utilities within 5 feet of excavation using vacuum excavation
- Hand-dig within tolerance zone of marked utilities
- Obtain installation utility records and compare to field markings
Step 3: Establish excavation perimeter and controls
Hazards
- Unauthorized entry into excavation zone
- Vehicle intrusion
- Public exposure
Controls
- Install barricades and warning signs around entire excavation perimeter
- Position jersey barriers or earth berms for vehicle protection
- Maintain minimum 6-foot setback for heavy equipment from trench edge
Step 4: Classify soil
Hazards
- Incorrect soil classification leading to inadequate protective system
- Unidentified soil layers or voids
Controls
- Competent person performs visual and manual soil tests per OSHA Appendix A
- Classify soil at each distinct change in conditions
- Document soil classification in excavation log
- Default to Type C if any uncertainty exists
Step 5: Install protective system (shoring, sloping, or shielding)
Hazards
- Cave-in during installation
- Crushing by trench box or shoring components
- Inadequate protective system for soil type
Controls
- Install protective system from outside the trench using mechanical placement
- Verify shoring or shield is rated for soil type and trench depth
- Tabulated data or engineer-stamped design available on site
- Never allow workers in unprotected trench during shield placement
Step 6: Excavate to design depth
Hazards
- Cave-in
- Struck by excavation equipment
- Falling into excavation
- Damage to adjacent structures
Controls
- Maintain protective systems as excavation progresses
- Spotter required when equipment operates near trench edge
- Place spoil minimum 2 feet from trench edge
- Monitor adjacent structures for signs of settlement or displacement
Step 7: Dewatering operations
Hazards
- Water accumulation undermining trench walls
- Electrocution from submersible pump
- Destabilization of adjacent soil
Controls
- Install sump pit and submersible pump with GFCI protection
- Discharge water to designated settling area per SWPPP
- Competent person evaluates trench wall stability after dewatering
- Monitor water table level and adjust dewatering as needed
Step 8: Provide means of egress
Hazards
- Workers trapped in trench during emergency
- Ladder displacement or failure
- Inadequate egress spacing
Controls
- Place ladders within 25 feet of lateral travel for all workers
- Extend ladders minimum 3 feet above trench edge
- Secure ladders at top to prevent displacement
- Inspect ladders daily before use
Step 9: Worker entry and operations in excavation
Hazards
- Cave-in
- Atmospheric hazards in deep excavations
- Struck by materials or tools from above
- Heat stress in confined trench
Controls
- Competent person inspects excavation before each shift and after any condition change
- Monitor atmosphere in excavations deeper than 4 feet where hazardous atmosphere may exist
- Prohibit work under raised loads or excavator bucket
- Implement heat stress prevention program for summer operations
Step 10: Backfill and compaction
Hazards
- Workers struck by backfill material
- Equipment rollover at trench edge
- Inadequate compaction causing future settlement
Controls
- Remove all personnel from trench before beginning backfill
- Remove protective systems from bottom up using mechanical extraction
- Compact backfill in lifts per project specifications
- Maintain equipment setback from unsupported trench walls
Step 11: Grade restoration and site cleanup
Hazards
- Uneven ground creating trip hazards
- Unmarked excavation area
- Soil erosion
Controls
- Restore grade to match surrounding terrain
- Install erosion control measures per SWPPP
- Remove all barricades only after excavation is fully backfilled and compacted
- Document final compaction test results
Competent & Qualified Persons
EM 385-1-1 requires designated competent and qualified persons for specific activities. These individuals must have the training, experience, and authority to identify hazards and take corrective action.
Excavation Competent Person
Must be capable of identifying existing and predictable hazards related to excavation, classifying soil types through visual and manual testing per OSHA Appendix A, selecting appropriate protective systems, and has authority to immediately stop work and remove workers when hazardous conditions develop.
EM 385-1-1 Reference: Section EM 385-1-1 Section 25.A.01
Site Safety and Health Officer (SSHO)
Must hold 30-hour OSHA Construction certification, have minimum 5 years construction safety experience, complete EM 385-1-1 40-hour training, and be designated in the Accident Prevention Plan. Must be on-site whenever work is in progress.
EM 385-1-1 Reference: Section EM 385-1-1 Section 01.A.17
Quality Control Manager
Responsible for reviewing and accepting AHAs before work begins on each DFOW, verifying that competent persons are designated by name, and ensuring the AHA is updated when conditions change.
EM 385-1-1 Reference: Section EM 385-1-1 Section 01.A.13
Equipment, Training & Inspection Requirements
Required Equipment
Training Requirements
- OSHA 10-hour Construction Safety (minimum for all workers; 30-hour for supervisors)
- EM 385-1-1 40-hour training for SSHO and competent persons
- Excavation competent person training covering soil classification, protective system selection, and daily inspection procedures
- Equipment operator certification for excavators and loaders
- Activity-specific orientation covering this AHA, the excavation plan, and site-specific hazards
Inspection Requirements
- Daily inspection of excavation by competent person before worker entry and after any rainstorm, freeze/thaw cycle, or vibration event
- Inspection of protective systems (shoring, shields, slope angles) at the start of each shift
- Pre-use inspection of ladders, pumps, and atmospheric monitoring equipment
- Weekly documented inspection of all excavation safety controls by SSHO
- Verification of utility locate markings before each day of excavation in new areas
Applicable OSHA Standards
29 CFR 1926.651
Specific Excavation Requirements
Requires underground utility location, safe means of egress within 25 feet, daily competent person inspections, protection from water accumulation, and a minimum 2-foot spoil setback from trench edges.
29 CFR 1926.652
Requirements for Protective Systems
Mandates sloping, benching, shoring, or shielding for excavations 5 feet or deeper unless in stable rock. References Appendices A through F for soil classification, sloping configurations, and shoring design tables.
29 CFR 1926.650
Scope, Application, and Definitions
Defines excavation, trench, competent person, protective system, and shield. Establishes the scope of Subpart P covering all open excavations made in the earth's surface.
29 CFR 1926.651(k)
Inspections
Requires daily inspections by a competent person for evidence of situations that could result in cave-ins, failure of protective systems, hazardous atmospheres, or other hazardous conditions.
Required Personal Protective Equipment
Frequently Asked Questions
What is the difference between a JSA and an AHA for excavation?
A Job Safety Analysis (JSA) is a general hazard analysis format used across all industries. An Activity Hazard Analysis (AHA) is the specific format required by EM 385-1-1 on USACE and DoD construction contracts. The AHA includes additional requirements not found in a typical JSA: a Risk Assessment Code (RAC) matrix rating for each work step, identification of the Definable Feature of Work (DFOW), specific EM 385-1-1 section references, competent person designations by name, and formal acceptance by the government representative before work begins.
At what depth does EM 385-1-1 require protective systems?
EM 385-1-1 requires protective systems for all excavations 4 feet or deeper, which is more stringent than OSHA's general 5-foot threshold under 29 CFR 1926.652. On USACE projects, the EM 385 standard governs, meaning contractors must install sloping, shoring, or shielding one foot earlier than what OSHA general industry standards require. When the excavation is in stable rock or the competent person determines there is no cave-in potential at lesser depths, protective systems may not be required, but this determination must be documented.
Who reviews and accepts the excavation AHA on a USACE project?
The AHA is prepared by the contractor and reviewed internally by the Site Safety and Health Officer (SSHO) and the Quality Control Manager. It is then submitted to the USACE Contracting Officer Representative (COR) or designated government safety representative for acceptance. The AHA must be accepted before the excavation DFOW can begin. If site conditions change significantly during the work, the AHA must be revised and resubmitted for acceptance.
How are RAC codes assigned for excavation work steps?
Each work step receives two RAC ratings: an initial (pre-control) RAC and a residual (post-control) RAC. The RAC is determined by plotting severity (Catastrophic, Critical, Marginal, Negligible) against probability (Frequent, Likely, Occasional, Seldom, Unlikely) on the EM 385-1-1 risk assessment matrix. For excavation, the initial RAC for steps involving trench entry is typically High (2) or Extremely High (1) due to the critical severity of a potential cave-in. After applying engineering controls (protective systems), administrative controls (competent person, inspections), and PPE, the residual RAC should be reduced to Medium (3) or Low (4-5).
What happens if unexpected utilities are encountered during excavation?
Work must stop immediately when an unidentified utility is encountered. The competent person and SSHO must be notified, the area must be secured, and the utility owner must be contacted for identification. On military installations, unmarked utilities may include classified systems that require coordination with the installation Directorate of Public Works. The AHA should include a stop-work protocol for unexpected discoveries, including contact numbers for the utility locating service, installation DPW, and the COR.