Trenching and Excavation Safety Program
- 12 & 15 Passenger Van Policy
- 3D Printer Policy
- Asbestos Floor Tile Policy
- Asbestos Policy
- Basic Electrical Safety Policy
- Bicycles and Other Transportation Vehicles in University Buildings
- Biohazards Medical Monitoring Policy
- Biological Waste Disposal Policy
- Building Code Enforcement Policy
- Chain Saw Safety Policy
- Compressed Gas Cylinders Condensed Safety Rules
- Compressed Gas Cylinders Use and Storage
- Confined Space Entry Policy
- Contractor Health and Safety Requirement Policy
- Dive Boat Safety Policy – Responsibilities
- Drones & Unmanned Aircraft System Policy
- Electronics Reuse/Recycle
- Fall Protection Policy
- Feral Cats & Other Wild Animals Living on Campus Policy
- Golf Cart Policy
- Hazard Communication Policy
- Hazardous Energy Control (Lock out/Tag out) Policy
- Hearing Conservation Policy
- Heat Stress Policy
- Hot Work Safety Policy
- Indoor Environmental Quality Policy
- Lab Closeout Policy
- Lead Paint Policy
- Mercury Spills
- Minors in Research Laboratories, Clinics, or Animal Facilities
- Motorcycle, Scooter (Includes E-Scooters)/Moped, Segway and Bicycle Use by Employees: Personal Protective Equipment Policy
- Natural Gas Leaks Policy
- Occupational Safety Forms
- Personal Protective Equipment
- Portable Power Tool Safety
- Powered Industrial Trucks (Forklifts)
- Q Fever/Coxiella burnetii in Sheep, Goats and Cattle Control Policy
- Recreational Use of the Lake Alice Watershed Policy
- Respiratory Protection Policy
- Shop Safety & Machine Guarding Policy
- Student Shop Safety Policy
- Temporary Structures on Campus (Including Tents)
- Tractor & Roll Over Protection Structures (ROPS) Safety Policy
- Trenching and Excavation Policy
- Vaccination Policy for Research Personnel
Scope and Application
This program sets forth the practices required for trenches or excavations with a depth of four feet or greater along any portion of its length that will be entered by University of Florida employees or students. All excavations or trenches 4 feet or greater in depth shall be appropriately benched, shored, or sloped according to the procedures and requirements set forth in this policy. Excavations or trenches 20 feet deep or greater must have a protective system designed by a registered professional engineer.
- On site evaluation to monitor use of safe work practices and procedures
- Assisting with atmospheric testing and equipment selection as needed
- Providing or identifying appropriate training for Competent Persons and staff
- Providing technical assistance as needed
- Reviewing and updating the program at least annually.
Additional training is required for any employee designated to be the competent person for a trenching and excavation job. Competent person training covers the following areas in detail:
- Hazards related to excavation work
- Work practices and selection of appropriate protective systems
- Methods of evaluating soil and the site
- Inspection procedures
- Specific requirements of the policy and of related policies
- Emergency procedures
Both the designated competent person and any other employee involved in trenching and excavating activities shall attend relevant health and safety training at least every two years or more often if necessary due to an observed disregard of the noted safety procedures.
- Must be trained in and knowledgeable of excavation and trenching standard, and other programs that may apply (Hazard Communication, Confined Space, Respiratory Protection)
- Must be capable of recognizing hazardous conditions and must have authority to stop work and ensure that hazards are corrected
- Performs and documents the ‘Daily Excavation Inspection’, and knows when inspections should be performed
- Must assure that the location of underground installations or utilities have been properly located.
- Must identify and ensure the use of adequate protective systems, work methods and personal protective equipment (PPE) on the excavation site.
The location of sewers, telephone, fuel, electric, water lines, or any other underground installations that may be encountered during excavation work must be determined and marked prior to opening an excavation. The Project Manager shall make arrangements as necessary with the appropriate utility agency for the protection, removal, shutdown, or relocation of underground installations.
If it is not possible to establish the exact location of these installations, the work may proceed with caution if detection equipment or other safe and acceptable means are used to locate the utility.
Excavations must not endanger the underground installations or the employees engaged in the work. Utilities left in place should be protected by barricades, shoring, suspension or other means as necessary to protect employees.
Guardrails, fences, or barricades shall be installed around excavations adjacent to walkways, roads, paths or other traffic areas. Use of barricade tape alone is not considered a sufficient method of isolation when the excavation is unattended. Warning lights or other illumination shall be used as necessary for the safety of the public at night.
Wells, holes, pits, and similar excavations must be effectively barricaded or covered and posted.
Walkways or bridges used by the general public to cross excavations must be equipped with standard guardrails.
To classify soil as type B the competent person shall use a visual test coupled with one or more manual tests.
Visual test: Evaluate the conditions around the site including the soil adjacent to the site and the soil being excavated.
Identify any signs of vibration. Check for crack-line openings along the failure zone, look for existing utilities that indicate that the soil has been previously disturbed, and observe the open side of the excavation for indications of layered geologic structuring.
Look for signs of bulging, boiling, or sloughing, as well as signs of water seepage from the sides or bottom of the excavation.
The area adjacent to the excavation should be evaluated for foundations or other intrusions into the failure zone, and the evaluator should check the spoil distance from the edge of the excavation.
Any one of the following will cause soil to be classified as Type C
- Water seepage into excavation
- Vibration from road traffic or equipment
- Signs of bulging, boiling, or sloughing
- Crack lines along failure zone
Dry strength test: Take a sample of dry soil. If it crumbles freely or with moderate pressure into individual grains it is considered granular (Type C). Dry soil that falls into clumps that subsequently break into smaller clumps (and the smaller clumps can only be broken with difficulty) it is probably clay in combination with gravel, sand, or silt (Type B).
Plasticity or Wet Thread Test Take a moist sample of the soil. Mold it into a ball and then attempt to roll it into a thin thread approximately 1/8 inch in diameter by two inches in length. If the soil sample does not break when held by one end, it may be considered Type B. A pocket penetrometer, shearvane, or torvane may also be used to determine the unconfined compression strength of soils.
Sloping: Maximum allowable slopes for excavations less than 20′ based on soil type and angle to the horizontal are as follows:
Type B soil must have walls sloped to a maximum angle of 45-degrees (1:1 slope) from horizontal in all directions.
Type C soil, must have walls sloped at a maximum angle of 34-degrees (1:1.5 slope) from horizontal in all directions.
Type B Soil
Benching is not permitted in Type C soil.
Trench boxes may be used in combination with sloping and benching. The box must extend at least 18 inches above the surrounding area if there is sloping toward the excavation. This can be accomplished by providing a benched area adjacent to the box.
Shields may be placed two feet above the bottom of an excavation, provided they are calculated to support the full depth of the excavation and there is no caving under or behind the shield.
Workers must enter and leave the shielded area in a protected manner, such as by a ladder or ramp. Workers may not remain in the shielded area while it is being moved.
Three vertical shores, evenly spaced, must be used to form a system. Wales are installed no more than two feet from the top, no more than four feet from the bottom, and no more than four feet apart, vertically.
- Daily and before the start of each shift.
- As dictated by the work being done in the trench.
- After every rain storm.
- When fissures, tension cracks, sloughing, undercutting, water seepage, bulging at the bottom, or other similar conditions occur.
- When there is a change in the size, location, or placement of the spoil pile.
- When there is any indication of change or movement in adjacent structures.
Temporary spoil shall be placed no closer than 2 feet from the surface edge of the excavation. The distance is measured from the nearest base of the spoil to the cut. This distance should not be measured from the crown of the spoil deposit. This distance requirement ensures that loose rock or soil from the temporary spoil will not fall on employees in the trench.
The spoil should be placed so that it channels rainwater and other run-off water away from the excavation. Spoil should be placed so that it cannot accidentally run, slide, or fall back into the excavation.
- Vehicle crossings must be designed by and installed under the supervision of a registered professional engineer.
- Walkways or bridges must have a minimum clear width of 20 inches, be fitted with standard rails, and extend a minimum of 24 inches past the surface edge of the trench.
Testing should be conducted before employees enter the trench and should be done regularly to ensure that the trench remains safe. The frequency of testing should be increased if equipment is operating in the trench that could produce airborne contaminants.
Employees required to wear respiratory protection must be trained, fit-tested, and enrolled in the UF respiratory protection program.
Trenches and excavations with hazardous concentrations of airborne contaminants or oxygen deficient atmospheres qualify as confined spaces. When this occurs, compliance with the UF Confined Space Program is also required.
Employees shall not be permitted to work in hazardous and/or toxic atmospheres. These include atmospheres with:
- less than 19.5% oxygen,
- a combustible gas concentration greater than 20% of the lower flammable limit,
- concentrations of hazardous substance that exceed those specified in the Threshold
Limit Values for airborne contaminants established by the ACGIH.
Protective methods for these circumstances must include:
- Use of special support or shield systems approved by a registered professional engineer.
- Water removal equipment used and monitored by a competent person.
- Safety harnesses and lifelines used in conformance with 29 CFR 1926.104.
During rainstorms employees must exit the trench. The excavation must be carefully inspected by a competent person after each rain and before employees are permitted to re-enter the trench. Protective measures such as diversion ditches and dikes should be used to limit surface runoff water from entering the excavation.
In the event of a serious injury or trapped worker requiring specialized rescue, 911 must be called immediately. UPD should be notified after the call to 911.
While waiting for emergency response personnel to arrive, workers at the site should take measures to support the rescue team and to further protect personnel on site.
- If the victim is not visible, try to identify the area where the victim is located
- Hand digging, if the excavation is stable and can be approached safely, can be carried out. No mechanical digging should be done due to the potential for inflicting additional injury to the victim.
- Assemble material that can assist in rescue operations such as shovels, plywood, ladders and buckets.