Presentation on theme: "PSFA Trench Rescue. Relevant Reference Material OSHA 29 CFR1926.650: Scope, Application and Definitions OSHA 29 CFR1926.651: Specific Excavation Requirements."— Presentation transcript:
PSFA Trench Rescue
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,
Introduction Each year, 1,100 workers are severely injured and 100 workers die in trenching and excavating accidents
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
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
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
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
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
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
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
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
Slough In (cave in) Most commonly occurs to previously excavated materials, primarily in sand, gravel mixtures Slough trench lip
Side wall shear Occurs commonly to clay type soils exposed to drying Side wall shear
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
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.
Padding the Lip
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
Trench Terms 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
Terms Terms Scabs-Hold timber shoring firmly in place against uprights. 2 x 4 pieces Spoil pile-The material excavated from the trench
Trench Terms Lowering lines- Line used to lower pneumatic shoring. Lines should be of a different color
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
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.
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.
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 Strut Extension Swivel strut base
Shoring Types Shoring Types Timbering: Difficult and time consuming task. 4 x 4 lumber generally used for timbering.
Shielding IV. Trench boxes are different from shoring because instead of shoring up the trench face, they are intended to primarily protect workers from slough ins.
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)
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”
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
Nailing Shores Nail half way into 45 swivel base and then bend nail over corner of base
Off Setting Shores
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
Hazard Control Hazards may include: – 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
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.
Safety First Appropriate PPE: – 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
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
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
Trench 100 Feet 250 Feet IC Personnel Staging 500 Feet Staging Rehab PIO Operations
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
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
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?)
Inner Circle Check 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
Operations: 4 Team Approach 1.-Excavation 2.-Monitoring 3.-Shoring 4.-Rescue
Excavation Coordinates operation for dewatering (if needed Initiates/completes lip safety Removes spoil pile, reduce angle of repose
Monitoring Monitors trench during entire rescue operation Establishes ventilation in all levels of trench Establishes back-up ventilation in case of primary ventilation failure
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
Cutting Table at the cut station
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
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)
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
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.