1. Excavation & Trenching Awareness Plus

2. Training Objectives
To explain the type of work which may constitute excavation work.
To understand what controls should be in place when excavation work is performed.
To ensure personnel understand the basic requirements and controls required to safety perform excavation work.
To provide details on where additional information can be obtained.

3. What is an Excavation? Excavation is defined as:
Any man-made cut, trench, or depression in the earth’s surface resulting from rock or soil removal.
This would include the breaking of any concrete surface of a facility.

4. General Excavation Requirements
Collect information and conduct an evaluation to determine potential hazards of the excavation site. This evaluation should include:
Determination of what is underground at excavation site, e.g. Utility lines and or piping (electrical, natural gas, water, etc)
Data collected can be found by review of underground drawings, electromagnetic scanning on the site, interviews of personnel with long time knowledge of the facility.
Excavate all underground utilities by hand using non-sparking tools.

5. General Excavation Requirements
(Continued from previous slide)
Determination made if the site of the excavation has previously been disturbed as it results in it being unstable.
If there are already structures on the site or it should automatically be considered as having being disturbed.
Review of soil analysis report for the site to determine the type and properties of the soil in the area.
Review of the above ground to determine any potential hazards such as: Overhead power lines within 4 meters (14 feet) of the excavation site and or buildings very close to the excavation that could be impacted by the excavation work.

6. General Excavation Requirements
(Continued from previous slide)
Determine if the soil in the site is contaminated with hydrocarbons are toxic substances.
If contamination determined all necessary safety precautions and conditions required to safely perform the work must be listed on the work permit.
For Excavation work that has been determined to be a medium or high risk a Job Safety Analysis should be completed.

7. Permit Requirements
Excavation work using hand tools only requires a General Work Permit to be issued.
If motorized equipment is to be used a Hot Work Form is required in addition to the General Work Permit.
If the excavations will be to a depth of 1.5 meters (5 feet) or greater a Confined Space Entry Form is required in addition to the General Work Permit.
Barricading and installation of signs to prevent personnel from falling in is required.
Warning tape and or cones are not a positive barrier and so can only be used temporarily (4 hours) until a proper barricade can be erected.
Barricades place around the excavation during periods when there is no work is being performed (nights) must be sufficiently strong enough to prevent a person from falling in. Use of caution tape and or cones as a barricade is not allowed except for short periods.
If the excavation is to be left unattended during there must be positive barricades installed to prevent any personnel or animals from falling in. In addition the area should be lit or if not battery power flashing warning lights san be used.
Note: Tell the class about a true incident that resulted in two deaths. It occurred at a service station which had a site excavated for a UST tank. The excavation was not barricaded but was cover with light weight plywood and left for the night. The station was closed and the exterior lighting in the area of the excavation were not own. There was no watch at the station during the night. A young boy riding a bicycle took a shortcut through the station on his way home and failed to see the cover excavation which was in his path. The boy and bicycle broke through the plywood. The boy although injured survived the fall and called for help. A passerby heard his cries for help and went into the excavation to rescue him. Unfortunately the soil in the excavation was contaminated and as a result the two were overcome by the vapors and were both asphyxiated.

8. Excavation Dangers
If mechanical excavation equipment cuts through an underground utilities line it can have catastrophic results.
The insert is a slide presentation of an explosion and fire that resulted in deaths when a bulldozer doing excavation work struck and broke a natural gas line in a remote area. There were no signs in the remote area to indicate there was an underground Natural Gas line

9. Excavation Dangers (continued)
Cave in of an excavation is a major concern and must be adequately addressed.
Cave in during excavations has resulted in several deaths due to engulfment of personnel.
For excavations, engulfment can occur when an individual is covered by the soil during a cave-in.

10. Excavation Dangers (continued)
Contaminated soil is a potential danger.
Gas testing should be undertaken prior to and during the excavation to check for soil contamination.
If contamination is found measures must be taken to address the potential hazards.
Discuss how such a fire could occur, noting that if the soil is highly contaminated there is the potential that inside the excavation the atmosphere could be too rich to burn as there would be insufficient oxygen. So how in such cases does the vapors then ignite, it is the result of the excavation bucket taking air (oxygen) into the pit. The ignition source was probably due to a spark from the bucket hitting a rock or other object creating a spark.
Fuel
Oxygen
Ignition Source

11. Excavation Dangers (continued)
Personnel must not enter into an excavation if standing water is present.
Water must be pumped out if it is contaminated or there is free product the pump used must be either explosion proof or air driven.
If water is contaminated it must be properly contained and treated.

12. Excavation Dangers (continued)
There are potential for various flammable or toxic gases to be present in an excavation, such as:
Methane
LPG
Gasoline vapor
Carbon Monoxide (CO)
Hydrogen Sulfide (H2S)
Sulfur dioxide (SO2)
Carbon Dioxide (CO2)
When flammable or toxic vapors are present special precautions should be taken to ensure the atmosphere is safe to enter.
Use of a blower or an eductor to purge the excavations atmosphere and ensure it is safe to enter may be required.
Motorized Blowers must be of an explosion proof type.

13. Preventing Cave-in Sloping of the excavation’s sides
All motorized excavation equipment, trucks, etc must remain a minimum of 1.0 meter (3 feet) from the excavation’s opening. It is advised that if space permits on the site a distance of 3 meters (12 feet) is maintained in order to ensure the weight and vibration created by the machine does not cause collapse of the excavations walls.
Note: The excavation equipment selected for use must have sufficient reach to maintain the minimum safe distance.
Removed soil should be stacked no closer to the excavation’s opening that 1.0 meter (3 feet)
Excavation equipment should only be operated by a trained and qualified Operator.

14. Preventing Cave-in
Benching of an excavation is another method that can be used to help ensure a cave-in doesn’t occur.
All motorized excavation equipment, trucks, etc must remain a minimum of 1.0 meter (3 feet) from the excavation’s opening. It is advised that if space permits on the site a distance of 3 meters (12 feet) is maintained in order to ensure the weight and vibration created by the machine does not cause collapse of the excavations walls.
Note: The excavation equipment selected for use must have sufficient reach to maintain the minimum safe distance.
Removed soil should be stacked no closer to the excavation’s opening that 1.0 meter (3 feet)
Excavation equipment should only be operated by a trained and qualified Operator.

15. Preventing Cave-in Installation of Shoring to prevent cave-in
Shoring must be designed by a qualified person
Shoring with bracing can be installed to prevent cave-in and protect workers.
Shoring materials can be either wood or metal sheet piling
Shoring shall be in stalled from the top town
Shoring shall be removed from the bottom up
Shoring bracing should not be welded inside the excavation itself as it presents a potential risk. Note: Should an exception to this rule be required it is to be considered as a high risk job task and a JSA specific to the hot work required should be completed. A Hot Work Form must be issued and it should require continuous gas testing at the location of the hot work.
The requirements to maintain a 1meter (3 feet) minimum distance for equipment and soil excavated from the excavation remains the same if shoring is used.

16. Preventing Cave-in of Trenches
Using a trench box for when working in trenches
When a trench box is used when moved along in the trench personnel must exit the trench.
Typical design of a
metal trench box

17. Access and Egress from Excavation
Ladders shall be installed in excavation to provide a means of access and egress.
Ladders shall be a maximum of 7.5 meters (25 feet) apart
Ladders should extend 1 meter (3 feet) or 3 rungs above the top of the excavation or trench and should be adequately secured.
Additional ladders should be installed if more than one worker will be in the excavation, it is suggested that for 5 persons two ladders should be installed and an additional ladder for every additional 5 persons.

18. Gas Testing at Excavation Site
Outside of the excavation (aboveground), the following is required based on gas detector readings:
If gas test indicates LEL concentration is Lower than 5% LFL/LEL, then no action is required an the excavation work can continue
If gas test indicates LEL is between 5 and 10% LFL/LEL, no work allowed unless the workers are wearing suitable respirators with organic vapor (OV) cartridge equipped with dust/particulate filters [or Supplied-Air breathing apparatus is used].
If gas test indicates 10% LFL/LEL or higher, evacuate the excavation site, determine the source and address appropriately.
During excavation work there can be a lot of dust or particulate matter present which can quickly plug the respirators organic vapor cartridges. By using the Particulate matter filters which can be changed out quickly and easily (they simple clip onto the inlet of the cartridges) the cartridges themselves will not become plugged.

19. Gas Testing in an Excavation
Inside the excavation (below ground), the following is required based on gas detector readings:
If LEL reading is above 0% LFL/LEL, but lower than 5%, workers entering must wear an Organic Vapor Cartridge Respirator with dust or particulate filter.
If LEL reading is between 5% and 10% LFL/LEL, workers must wear supplied-air respirators.
If LEL reading is 10% LFL/LEL or higher, evacuate
Caution, if there is high flash point flammable product in the excavation it will normally not register LEL present, but such free product is still flammable and a significant hazard that should be addressed.
Note: In cases where there the LEL is above 5% consider ventilating the excavation to reduce the concentration of flammable vapors.
If motor driven ventilators are to be used they must be of a suitable type for work in a hazardous environment (e.g. intrinsically safe). The blower and ducting must be bonded and the unit grounded to prevent a possible static discharge from occurring during operation. In addition, consideration must be given to where the vapors shall be exhaust to, it should be to a safe location where it will not come in contact with any ignition source while the flammable gas concentration is within the flammable range.

20. Excavation Form - Section “A”
The Excavation Form can only be used in conjunction with a General Work Permit it is not a permit itself.
Section “A” is the basic information section which allows the Requester to enter all the relevant information concerning the excavation work.

21. Excavation Form – Section “B”
Section “B” is to list general safety precaution required to be followed during the excavation.
Section “B” is a check-off lists related to precautions that may be required to perform the excavation safely. In addition it provides space for the additional comments to be listed. Section “B” must be completed by a competent person.

22. Excavation Form-Section “C”
Approval Section of the form where the relevant personnel sign-off on the form acknowledging the excavation work can be carried out.
Note: This form is not a Permit to perform excavation work, it is to used to supplement the General Work Permit for the excavation work.
Section “C” This is the approval section which allows the relevant party to sign the form noting that if all requirments noted are met the excavation can be done safety in their opinion.

23. What about this shoring?

24. What wrong with this photo?
Self explanatory

25. Excavation & Trenching – Additional Information
For additional details on Excavation & Trenches requirements refer to:
Your company’s operating procedures
Your Company’s Safety Department
Your client’s Safety Department