TRENCH OPERATIONS For safety is not a gadget but a state of mind. ~Eleanor Everet

Objectives Governing Standards Governing Standards Anatomy of a Trench Anatomy of a Trench Soil Physics Soil Physics First arriving units actions/ Scene management First arriving units actions/ Scene management Equipment Familiarization Equipment Familiarization Type of Trench Collapses Type of Trench Collapses Assignments & Responsibilities Assignments & Responsibilities Techniques for Protection Techniques for Protection

OSHA CFR 1926 Subpart P, Excavation: –Important to rescuers for several reasons  First the data and information will give you the information from which you can decide the protective systems.  Secondly, knowledge of the standard, its requirements, protective systems, and soil classifications will qualify the user as a “Competent Person”.

General requirements All trenches must be protected before entries except:  Those made entirely of stable rock.  Those less than five feet in depth, including the height of the spoil pile must be protected. Protection: Protection: –Anything more than five feet in depth, including the height of the spoil pile must be protected. Spoil Pile: Spoil Pile: –Must have two-foot set back for the lip. Egress: Egress: –Trenches four feet or greater in depth must have a means of egress every twenty-five feet “Ladders”. Atmospheric: Atmospheric: –Trenches four feet or greater in depth must be tested before entry.

Definitions A “trench”, means a narrow excavation (in relation to its length) made below the surface of the ground. In general, the depth is greater than the width, but the width measured at the bottom is not greater than 15 feet. A “trench”, means a narrow excavation (in relation to its length) made below the surface of the ground. In general, the depth is greater than the width, but the width measured at the bottom is not greater than 15 feet. WIDTH DEPTH DEPTH

”Excavation”, includes a trench It means any man made cut, cavity, trench, or depression in an earth surface formed by the earths removal. Again, in practical terms, when a hole is more than 15 feet wide at its base, it is called specifically an excavation. Overall, an excavation is wider than it is deep. It means any man made cut, cavity, trench, or depression in an earth surface formed by the earths removal. Again, in practical terms, when a hole is more than 15 feet wide at its base, it is called specifically an excavation. Overall, an excavation is wider than it is deep.

Competent Person One who can identify existing or predictable hazards in the surrounding that are unsanitary, hazardous, or dangerous to employees. Also has authorization by the nature of their position to prompt corrective measures to eliminate them. The person shall be knowledgeable in the requirement of this part. One who can identify existing or predictable hazards in the surrounding that are unsanitary, hazardous, or dangerous to employees. Also has authorization by the nature of their position to prompt corrective measures to eliminate them. The person shall be knowledgeable in the requirement of this part.

Anatomy

How Heavy is Dirt? Physical forces associated with collapse: Physical forces associated with collapse: –Dirt has volume that has mass and weight –One cubic foot of dirt weights between 85 and 125 pounds per cubic foot.

Weight of a Volkswagen 2,785 Pounds Weight of one cubic yard of soil 2,700 Pounds

Soil Physics Compounding the effects of gravity is hydrostatic pressure Compounding the effects of gravity is hydrostatic pressure Add the weight of water and rock, a cubic foot of dirt can be as much as 125 pounds per cu/ft Add the weight of water and rock, a cubic foot of dirt can be as much as 125 pounds per cu/ft

A six foot trench: A six foot trench: –at the four foot level has approximately 400 pounds vertical weight. –Lateral forces could be expected to be 132 pounds of horizontal pressure –Distribution of lateral pressure occurs on about a 45 degree angle from the bottom

Accidents without cave-ins –Most emergencies in trenches deal with something other than a collapse –Most of the work is done after the trench has been dug –In these cases don’t be lulled to sleep by a protected trench –Approach identically as an open trench

Hazards Present?

First Arrival Apparatus spotting Apparatus spotting –Spot at least 100 ft from location Create Exclusion Zones (on next slide) Create Exclusion Zones (on next slide) Size-up – accurate address of location, call for help Size-up – accurate address of location, call for help Secure RP, job foreman, or witness to accident Secure RP, job foreman, or witness to accident Safety 360 Review – approach trench from the end, Secondary size- up Safety 360 Review – approach trench from the end, Secondary size- up Rescue or Recovery mode Rescue or Recovery mode Assess potential hazards to rescuers (Atmospheric, water,Trench etc) Assess potential hazards to rescuers (Atmospheric, water,Trench etc) Make The Trench Lip Safe – ground pads/ Ladder bridges Make The Trench Lip Safe – ground pads/ Ladder bridges Shielding of patient – with material on site, plywood, backboard Shielding of patient – with material on site, plywood, backboard Air monitoring – Bottom at patient, middle and top of trench Air monitoring – Bottom at patient, middle and top of trench Apparatus Base Area with manager. location? Apparatus Base Area with manager. location?

Trench Scene Management Exclusion Zones Hot Zone 0 – 100 ft. Hot Zone 0 – 100 ft. Warm Zone 100 – 150 ft Warm Zone 100 – 150 ft Cold Zone 150 – 300 ft. Cold Zone 150 – 300 ft.

Ground pads For distribution of weight on trench edge For distribution of weight on trench edge

Ladder Bridge

Review of Monitoring Values

Equipment Familiarization Strongbacks/Uprights = Shoring Panels Strongbacks/Uprights = Shoring Panels Timber Timber Waler Waler Palm nailer Palm nailer Airshore Airshore Speedshore Speedshore

Types of Collapses Spoil pile slide  Excavated earth too close to the lip  Heavy rain increasing wt of pile

Slough In / Lip slide Slough failure  The loss of part of the trench wall

Sheer Wall Shear wall collapse  section of soil that loses it’s ability to stand

Toe Failure Toe failure  Slough that occurs at the bottom  Found in location of fill dirt

Bell Pier Condition Bell pier condition  Long term toe failure on both sides

Wedge Failure Wedge failure  Occurs with intersecting trenches, T or L Trench  Angled section of earth falling from the corner of an intersecting trench

Assignments and Responsibilities Extrication/ Entry Team Extrication/ Entry Team –Developing plan for patient extrication –Also personnel used for digging –Assists Shoring Team to set shores Shoring Team Shoring Team –Assembling, placing and removing shoring & walers Panel Team Panel Team –Place ground pads –Prepare and placement of panels

TECHNIQUES FOR TRENCH PROTECTION Ops operating within trench Ops operating within trench Straight wall trench procedures: Straight wall trench procedures: –Set middle set of panels as directly over the victim as possible –For Pneumatic Struts:  Set middle shore  Set top shore  Set bottom shore

TECHNIQUES FOR TRENCH PROTECTION

Outside Waler –Uses outside walers to span opening Outside waler procedures: Outside waler procedures: –Place pickets to tie walers –Place and tie off bottom of Waler –Place and tie off top of Waler –Set middle set of panels as directly over victim as possible

Inside Waler Inside walers are used to span a set of panels for the purpose of creating an open space Inside walers are used to span a set of panels for the purpose of creating an open space

The intersecting “T” trench is a very unstable trench because not only is one wall exposed, but a section has been cut that intersects the other wall. The intersecting “T” trench is a very unstable trench because not only is one wall exposed, but a section has been cut that intersects the other wall.

The “L” trench can be describe as two trenches that intersect at there ends The “L” trench can be describe as two trenches that intersect at there ends

Deep trenches are those trenches over 10 feet but not more than 20 feet Deep trenches are those trenches over 10 feet but not more than 20 feet

Pier-hole

Trench Environments

Take Home Points Create a Hot, warm and cold zone Create a Hot, warm and cold zone –Hot zone 0 – 100 ft –Warm zone 100 – 150 ft –Cold zone 150 – 300 ft Call for help, location, Staging Call for help, location, Staging Control Traffic movement Control Traffic movement Shut down all heavy equipment operating within 300 ft of the collapse Shut down all heavy equipment operating within 300 ft of the collapse Ladders for egress every 25 feet. Ladders for egress every 25 feet. Ground pads Ground pads Air monitoring Air monitoring Spoil pile moved 2 feet from lip of trench Spoil pile moved 2 feet from lip of trench

Questions? Thank you For safety is not a gadget but a state of mind. ~Eleanor Everet

Rotational Failure Rotational failure  Scoop shaped collapse that starts at the lip and transmits itself to the trench walls