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Excavating and Trenching

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Charles Attaway

on 9 October 2012

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Transcript of Excavating and Trenching

Subpart P Excavating and Trenching About two workers are killed every month in trenching or excavating accidents Hazards of Excavation OSHA information on Excavation Planning for Safety Excavation Trench Box and Shield Charles Attaway
Eric Fletcher
Todd Rapoport
Brittany Smyth Excavating and Trenching are defined as two separate items within OSHA regulation Excavating- any man-made cut, cavity, trench or depression in an earth surface made by earth removal Trenching- narrow underground excavation that is deeper than it is wide, and it is no wider than 15 feet Cave-ins
Falls
Falling Objects
Moving Equipment
Hazardous Atmospheres
Underground Utilities Lack of cave in protection was the #2 cited violation this past year Research done by OSHA in the 1980's during the revision of the standards showed that the fatality rate in excavation work was 112% greater than that of construction in general Case #1 Case #2 Standards and Regulations-1926-Subpart P-Excavations
Technical Manual-Section V, Chapter 2
Construction Industry Safety and Health Outreach Program 1926-Subpart P- Excavations Purpose: Sets guidelines/rules that contractors and subs must follow
1926.650 - Scope, application, and definitions applicable to this subpart.
1926.651 - Specific Excavation Requirements.
1926.652 - Requirements for protective systems.
1926 Subpart P App A - Soil Classification
1926 Subpart P App B - Sloping and Benching
1926 Subpart P App C - Timber Shoring for Trenches
1926 Subpart P App D - Aluminum Hydraulic Shoring for Trenches
1926 Subpart P App E - Alternatives to Timber Shoring
1926 Subpart P App F - Selection of Protective Systems Technical Manual- Section V, Chapter 2 Focus: Trenching and Shoring
Purpose: make people(safety officials) aware of hazards and how to prevent them
Introduction
Definitions
Overview: Soil Mechanics
Determination of Soil Type Test Equipment and Methods for Evaluating Soil Type
Shoring Types
Shielding Types
Sloping and Benching
Spoil
Special Health and Safety Considerations
Bibliography Outreach Program Purpose: Teaches the steps in planning for safety
Also provides training for workers and employers
Planning for Safety
Pre-Construction
On-the-Job Evaluations
Support Systems
Safety Precautions
Installation and removal of protection systems
Material and Equipment
Falls
Water Accumulation
Hazardous Atmospheres
Access and Egress Pre-Bid Nearby Traffic
Proximity and physical condition of nearby structures
Soil
Surface and ground water
Location of the water table
Location of overhead and underground utilities Pre-Construction Safety and Health Program Systematic Identification
Evaluation
Prevention/Control of hazards
Can be written or verbal but must be unique to the project Training Train every employee
Incorporate fast notification and investigation of accidents On-the-job Evaluation Inspections Competent Person
Daily
After natural events (rain)
After man made events(blasting) What is Inspected? All excavations
Adjacent areas for possible cave-ins
Protective systems and equipment
Proper use of safety equipment
Hazardous Atmospheres/ Conditions Soils impact on Excavation Support Systems Sloping/ Benching Standards.. Shoring Hydraulic Systems
Steel/Plywood Plates
Prevent Collapse Piles Deep Excavation
Driven Prefabricated Sections Shielding Trench box
Protect Workers Sloping Shielding or Shoring Sloping-General Rules No steeper than 1 to 1 1/2 slope (34 Degrees) Type C soil
20 ft depth or less Any gradation less than this is acceptable for any type of soil Sloping Guidelines No Sloped Trench may be more than 20' deep Sloping Shoring Trench Box/ Shield OSHA regulation does not require any protective system when an excavation is made entirely of solid rock or is less than 5 ft. deep and has been examined by a competent person Trench Boxes Trench Boxes Designed to allow workers to do their jobs within the plates of the box Trench boxes Engineered steel or aluminum structures that are used to protect workers inside trenches
Stand-up time- amount of time a trench will last from the time its dug till the time its walls start to cave in (a few seconds to several months) Improper use of a trench box Trench boxes always more expensive? Chart above is a comparison of soil removal quantities and costs for a two-mile trench that is 5' wide and 15' deep. Support System Design Factors Design Factors Soil classification
Depth
Water content
Weather/climate
Other operations in the vicinity Design must resist forces calculated for the full depth of the trench Safety Precautions OSHA standard prohibits excavation under level of a base, footing, foundation, or retaining walls Unless: Entirely stable rock
Support System(underpinning) provided
RPE determines structure is significantly removed from the excavation Installation and removal of protective systems Procedures
Securely connect members
Safely install
Never overload members
Install temporary structural members when necessary Excavation below bottom members of the support system = 2 feet or less
Support system to be removed from bottom up Falls and Equipment Materials/Equipment at least 2 ft
Provide warning systems
Barricades
Signals
Stop logs
Alert operations
Prohibit employees from working above others (sloped/benched)
Prohibit employees working under loads handled by digging/ lifting equipment Hazardous Atmosphere Provision Test any excavation where oxygen deficiency or hazardous atmosphere exists
Respiratory Protection or ventilation Employer must provide emergency rescue equipment
Breathing apparatus
Safety harness/line
Basket stretcher
Etc. Hazardous Atmospheres Examples Oxygen Deficient Atmospheres
Rainwater+limestone=acidity reaction=carbon dioxide
Flammable/Combustive/Explosive Atmospheres
VOC's from petroleum products (buried tanks etc.)
Methane-naturally from breakdown of certain materials( sewage, leaves, weeds)
Toxic Atmospheres
Carbon monoxide from vehicles or equipment Access and Egress Excavations deeper than 4 ft
Safe means of egress within 25 ft of lateral travel
-Ladders, steps, ramps, runways, etc
Ramps/ Runways
-designed by a competent person
-Uniform thickness/properly joined Conclusion... Top Cited Standards Specific excavation requirements
Requirements for protective systems
Head Protection
Hazard Communication
Safety Training and education February 2006. 29-year old male laborer killed in a trench collapse at a private residence.
working with four other men correcting a drainage problem
tried hand digging him out until local response team arrived
took almost 45 minutes to uncover the victims head after the collapse Landscaping company had been in business for 15 years (victim employed for five years)
Foreman not present at site day of accident Prior to this incident the company owner had never been cited for safety or health violations
Cited violations for incident
not having a health and safety program
not having person to render first aid
no qualified person to inspect excavation
not having proper procedures to prevent trench collapse under the excavation, trenching, and shoring rules March 2005. 35-year old plumber killed in a trench cave in when connecting sewer lines to a sewer main
7' deep, 3'wide
not sloped
previously dug up by other utilities Test any Excavation >4 ft Plumbing contractor in business for 17 years and had 70 employees
Had a written safety program & an Injury and Illness Prevention Program
Mandatory monthly safety meetings
Tailgate safety meetings
Specialized training program
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