1. PSFA Trench Rescue

2. Relevant Reference Material
OSHA 29 CFR : Scope, Application and Definitions
OSHA 29 CFR : Specific Excavation Requirements
OSHA 29 CFR : Requirements for Protective Systems
OSHA 29 CFR 1926 Subpart B Appendices A-F
National Fire and Rescue; Trench Rescue Secrets, Parts 1 & 2. Patrick Moore
FEMA Structural Collapse Technician Course, Student Manual, Module 2B Shoring Construction,

3. Introduction
Each year, 1,100 workers are severely injured and 100 workers die in trenching and excavating accidents

4. Why do trench accidents occur??
Complacency
Shortcutting of safety for profit
Weekend warriors-no shoring utilized
Ignorance of hazards
Unprepared or poorly trained in excavation

5. Anatomy of a Trench
Trench-Trenches are narrow excavations made below the surface of the ground. In general, the depth is greater than the width. However, the width of a trench is not greater than 15 feet. An excavation is also considered to be a trench
In reality, an open grave waiting for an occupant

6. Inherent trench problems
Natural and man made forces began acting immediately to close a trench once its been created
These forces overcome the strength of the soil composition and cause the trench to eventually collapse

7. Dirt Dynamics 1 cubic foot of dirt weighs 100 lbs
1 cubic yard of dirt weighs 2,700-3,500 lbs
1 cubic foot of dirt will fill eight 1 gallon buckets
1 cubic yard of dirt will fill gallon buckets 3 1 1 3 3 1 3

8. Soil Types
Type A-Most stable:clay, silty clay and hardpan (resists penetration) No soil is type A if it is fissured, is subject to vibration of any type, has previously been disturbed or has seeping water
Type B-Medium stability:silt, sandy loam, medium clay and unstable dry rock, previously disturbed soils unless otherwise classified as Type C. Soils that meet the requirements of Type A soil but are fissured or subject to vibration

9. Soil Types continued:
Type C-Least stable:gravel, loamy sand, soft clay, submerged soil or dense, heavy unstable rock and soil from which water is seeping freely

10. Soil Effects on Victim Traumatic Asphyxiation
Soil restricts expansion of victims chest
Soil blocks airways
Causes suffocation
Impact crushes the victim:
Breaking limbs
Causing internal injuries
Causing soft tissue injuries

11. Victim Survival Profile
Time is the biggest factor
8-10 min.’s for response
6-10 min.’s for initial assessment
18” of dirt = pounds
Hazard Risk Assessment Profile needs to be considered

12. Types of Trench Accidents
Spoil pile slide
Occurs when improper techniques are used and the excavated material is not placed far enough away from the trench lip
UNSAFE

13. Slough In (cave in) Slough trench lip
Most commonly occurs to previously excavated materials, primarily in sand, gravel mixtures

14. Side wall shear Occurs commonly to clay type soils exposed to drying

15. Trench Terminology
Lip extends 2 feet vertically and horizontally from the edge of the trench. If the spoil pile is located within 2 feet of the trench, it must be removed.
Lip

16. Padding the Lip
Acceptable materials: 2 x 12 lumber, 4 x 8 ¾” or 5/8” plywood or trench panels. Should extend from an area of stability to instability, if end of trench is accessible, start there.

17. Padding the Lip

18. Trench Terms Angle of Repose
The greatest angle above the horizontal plain at which loose soil will lie without sliding. Reducing this angle will reduce the amount of spoil slide

19. Trench Terms
Uprights-Vertical supports that attach panel to upright. Shoring is attached to uprights between panels (usually 2 x 8’s or 12’s)
Panels-Support side walls of trench Pre-made Shore form panels, 4 x 8 sheeting of 2 ¾” plywood
Shoring-Horizontal bracing between panels, can be pneumatic or timber shoring

20. Terms
Scabs-Hold timber shoring firmly in place against uprights. 2 x 4 pieces
Spoil pile-The material excavated from the trench

21. Trench Terms
Lowering lines-Line used to lower pneumatic shoring. Lines should be of a different color

22. Making the Trench Safe Three ways to “safe” a trench:
1.-Slope the angle of repose
2.-Benching
3.-Shoring/Shielding
Sloping the angle of repose and benching require backhoes as well as additional manpower.
Shoring operations require well trained coordinated rescuers

23. Shoring Basics
Shoring Types:Shoring is the provision of a support system for trench faces used to prevent movement of soil, underground utilities, roadways and foundations.

24. Shoring Types Hydraulic Shoring:
A prefabricated strut and/or system manufactured of aluminum or steel. Pressurized w/5 gal hand pump to psi. Pressure must be maintained, no locking device.

25. Shoring Types Pneumatic Shoring System:
Works in a manner similar to hydraulic shoring, primary difference is that pneumatic shoring uses air pressure to set shores (can be set manually)
Pneumatic Strut
Swivel strut base
Strut Extension

26. Shoring Types
Timbering: Difficult and time consuming task. 4 x 4 lumber generally used for timbering.

27.                                                                                                                                   
                                                                                                                                  
Shielding
Trench boxes are different from shoring because instead of shoring up the trench face, they are intended to primarily protect workers from slough ins.

28. Shoring Operations
Shores should be located 18”-24” from the floor and the lip of the trench
Shores should be no more than 48” apart vertically
Placement of the first shore should be from the outside of the trench using hydraulic/pneumatic shoring (shores should not be placed directly above the pt/victim)

29. Pneumatic Shoring Order
First shore should be placed in the middle of the upright
Second shore is placed in the top of the upright
Third shore is paced in the bottom of the upright
shores are lowered by lowering lines directed by the shoring officer then “shot”

30. Shooting Shores
After shore is lowered and is in place (level), the following commands are to be given by shoring officer:
“Prepare to Shoot”
“Shoot”
Pneumatic shores are shot at 100 psi and released at 150 psi

31. Corner Shoring

32. Corner Shoring

33. Corner Shoring

34. Nailing Shores
Nail half way into 45 swivel base and then bend nail over corner of base

35. Off Setting Shores

36. Timbering
The first shore is placed at the top of the upright and requires the rescuer to enter the trench on a ladder
The second shore or middle shore is placed in the middle of the upright, again forcing rescuer further in the trench on a ladder
Last shore is placed on the bottom of the trench above trench floor

37. Hazard Control Hazards may include: Vibration from:
Electrical utilities
Ruptured gas lines
Broken water/sewer lines
Workers on scene
Spoil pile
Falling debris in trench
O2 deficient atmosphere
Vibration from:
Operating machinery on scene
Nearby traffic
Responding apparatus

38. Rescue Operations DO NOT GO INTO THE HOLE!!!!
First and foremost, the company officer needs to limit the possibility of further injuries and death, get the hole under control, make it safe for everyone, and, with the proper equipment, start to develop a safe work space.

39. Safety First Appropriate PPE: Make the general area safe:
Dress for success, right gear should include head, hand, foot, eye, ear and respiratory protection as appropriate.
Make the general area safe:
Establish a hot, warm and cold zone

40. Safe the General Area First arriving apparatus:
Stops and is turned off no less than 250’ from the dispatched location. This becomes the warm zone
Establish command and designate a staging area for other other responders with equipment/apparatus.
Assign a staging officer

41. Cold/Hot Zone
Cold Zone Staging should exceed 500’or more from trench incident site
Hot Zone Area:
Should extend 100’ in all directions around the site
Use fire line tape, rope, etc. to mark these zones

42. Rehab PIO IC Operations Trench Staging 100 Feet 250 Feet 500 Feet
Personnel
Staging IC
250 Feet
500 Feet

43. Outer Circle Check Restrict entry to site
Eliminate sources of vibration, stop and shut down construction equipment
Identify witnesses to the accident if any
Identify job foreman
Begin to establish incident perimeters

44. Inner Circle Check Approach site from end of trench
Identify victim location (if possible) using witnesses, location of trench failure, surveyors markers etc.
Identify number of patients
Establish patient/victim condition if possible

45. Making the Rescue Scene Safe
Means monitoring the environment around the incident site. There is a good chance a hazardous environment exists and perhaps oxygen deficient space. Remember established confined space limits and use them to define problems. (Limited air?? Limited access?? Is the space continuously monitored?)

46. Inner Circle Check Establish full command structure
How is the patient trapped?
-totally buried, if so, where??
-trapped by utilities
Where???
Don’t forget to consider Hazard Risk Assessment Profile
Direct non trapped workers out of trench
Establish full command structure

47. Operations: 4 Team Approach
1.-Excavation
2.-Monitoring
3.-Shoring
4.-Rescue

48. Excavation Coordinates operation for dewatering (if needed
Initiates/completes lip safety
Removes spoil pile, reduce angle of repose

49. Monitoring Monitors trench during entire rescue operation
Establishes ventilation in all levels of trench
Establishes back-up ventilation in case of primary ventilation failure

50. Shoring Shores trench with pneumatic, hydraulic, timber shoring
Establishes cutting table if needed
Establishes air supply for pneumatics with back up supply
Under control of a shoring officer

51. Cutting Table at the cut station

52. Rescue Prepares and executes disentanglement procedures
Patient/victim packaging
Patient/victim removal
Rope system if needed (4:1, 5:1)
A-Frame/gin pole if needed

53. Rescue Disentanglement procedures:
-Remove dirt/soil away from victim, accomplished by hand digging and buckets
-Clear the head and chest if victim caught in collapse in this position
-Secure patient using acceptable devices
(LBB, LSP, Reeves, Stokes, Harnesses)

54. Rescue Be prepared for vertical extrication:
Consider A-Frame (engine co. task) construction away from hot zone and radio for it when ready
Mechanical advantage system needed
Shoring position may be impede vertical pt/victim removal

55. A-Frame Use

56. A-Frame

57. Summary
Managing the incident is the key to maintaining control, because you run a very good chance of working eight hours or more in many cases. Incident complexity and risk demand strong command, control and decision making ability.
Hazards in a trench rescue can be deadly and strike without little or no warning.

58. DON’T GET DEAD