Transcript Document
Excavation
1926 Subpart P for construction Maurizio Delcaro Occupational Health & Safety Specialist www.montanasafety.com
Excavation
1926 Subpart P for construction Agenda
General Requirements Competent Person Soils Analysis Sloping and Benching Affected Zone Shields and Shores Other Matters
Maurizio Delcaro Occupational Health & Safety Specialist www.montanasafety.com
Who are you?
Name?
Trade?
Construction or GI?
Why this excavation class?
Any other safety training?
Some things to think about.
Greenwood rescuers pull injured worker from trench “The construction crew hadn’t built a trench box to prevent the sides of the trench from collapsing, so firefighters were forced to spend about an hour shoring up the sides of the ditch before they were able to give assistance . The man was rescued about 80 minutes after the accident...” These guys will not enter an unprotected trench. (It caved in)
National Excavation News Apr 7, 2010 Crews still digging for workers trapped in trench... – Hudson Hub
Times
Apr 7, 2010 OSHA fines Stamar for trench death – MSN Apr 14, 2010 Trench called ' unsafe ' after worker dies in cave-in – Aurora Advocate Apr 14, 2010 Cave-in survivor still in hospital – Hudson Hub Times May 3, 2010 Fatal construction site accident – WKBW-TV May 3, 2010 Trench collapse death ruled accidental – Standard Speaker May 4, 2010 Contractor dies in cave-in at home construction site – WCAX May 4, 2010 Construction worker killed
News
as embankment collapses – The Buffalo May 5, 2010 Employee Caught in 16-Foot Hole; Contractor Cited – safety.blr.com May 7, 2010 Worker killed as embankment collapses – New York Injury News May 12, 2010 Contractor cited for cave-in hazards , other trenching... – OHS Online
National Excavation News May 12, 2010 Construction site owner is acquitted in day laborer’s death
Times
– NY May 17, 2010 State cites Veolia Water over safety concerns
Journal
– Indianapolis Bus. May 18, 2010 Worker freed after trench collapses – Ultimate Fort Bend Jun 9, 2010 Man rescued from trench collapse – ABC 4 News Jun 10, 2010 Boss: Worker on ground when trench gave way – Chronicle-
Telegram
Jul 9, 2010 Clay ball traps Minn. man in trench – Minneapolis Star Tribune July 26, 2010 Cave-in hazards
Online
could cost Connecticut contractor $61,800 – OHS July 29, 2010 Worker dies in cave-in at Pacific Palisades Homes – LA times July 30, 2010 Rescuers pull man out of Baldwin trench – WTAE Pittsburgh Aug 6, 2010 Identities released in trench death
– thenorthwestern.com
Aug 10, 2010 Excavator flips, kills man in Waterbury – WFSB News
National Excavation News Aug 16, 2010 Cave-in death leads to willful charges... – OSH Online Aug 21, 2010 Man in Redford dies after being trapped in trench
– WDBJ.com
Sep 1, 2010 Contractor fined for cave-in hazard – WPRI Eyewitness News Sep 29, 2010 Man seriously injured
Register
in Milford trench collapse
– New Haven
Sep 30, 2010 Police ID Michigan worker killed
Tribune
in trench collapse – Chicago Oct 5, 2010 OSHA cites Poland company in deadly
FMJ.COM
construction accident – Oct 10, 2010 Company cited in fatal trench cave-in – Hudson Hub Times Oct 14, 2010 Greenwood rescuers pull injured worker from trench – Indy Star
Some things to think about.
What is a competent person?
The CP can identify hazards.
According to OSHA, a competent person must be able to: IDENTIFY EXISTING AND PREDICTABLE HAZARDS IN THE SURROUNDINGS OR WORKING CONDITIONS WHICH ARE UNSANITARY, HAZARDOUS, OR DANGEROUS TO EMPLOYEES.
Let’s see some hazards...
The CP can identify and eliminate hazards.
According to OSHA, a competent person must be able to: IDENTIFY EXISTING AND PREDICTABLE HAZARDS IN THE SURROUNDINGS OR WORKING CONDITIONS WHICH ARE UNSANITARY, HAZARDOUS, OR DANGEROUS TO EMPLOYEES.
and have authorization to: TAKE PROMPT CORRECTIVE MEASURES TO ELIMINATE THEM
There must be an employer- designated hazard corrector.
If no one has authority to correct hazards, there can be no competent person.
The CP can identify and eliminate hazards.
According to OSHA, a competent person must be able to: IDENTIFY EXISTING AND PREDICTABLE HAZARDS IN THE SURROUNDINGS OR WORKING CONDITIONS WHICH ARE UNSANITARY, HAZARDOUS, OR DANGEROUS TO EMPLOYEES.
and have authorization to: TAKE PROMPT CORRECTIVE MEASURES TO ELIMINATE THEM
Clarification “... To be a competent person for purposes of this standard: One must have had specific training in, and be knowledgeable about soils analysis , the protective systems , and the requirements of the standard .
One who does not have such training or knowledge cannot possibly be capable of identifying existing and predictable hazards in excavation work...”
The competent person knows a ladder must be within 25 feet of workers in the excavation.
This is their means of egress.
Typically ladders are located inside a shield (trench box).
Stepladders are not to be used as fixed and/or extension ladders.
Some shields have fixed ladders.
When should a CP do inspections?
Daily Before each shift The spoil pile is getting bigger...
When it snows Bulging When it rains Undercuttin g Fissure s Cracks in the soil Any significant weather change Did someone move the spoil pile?
Water seepage Loose rock or soil After a wind storm
What is a competent person?
Soils Analysis
What is soils analysis?
Has anyone performed a soils analysis before?
What are the soil types ?
Which methods are used to determine soil type?
Quaternary clay
The competent person classifies soil.
“Each soil and rock deposit shall be classified by a competent person as Stable Rock, Type A, Type B, or Type C...
... in accordance with the definitions set forth in paragraph (b) of this appendix.” Rhyolite from ancient volcanic activity.
Here’s how to classify the soil type.
“The classification of the deposits shall be made based on the results of at least one visual and at least one manual analysis.
Such analyses shall be conducted by a competent person using tests described in paragraph (d)...” Silty loam
Here’s how to classify the soil type.
“The classification of the deposits shall be made based on the results of at least one visual and at least one manual analysis.
“... or in other recognized methods of soil classification and testing ...” Many send their samples to a lab.
So can you.
Stable Rock “Natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed.” Palisade Head, formed from rhyolitic lava flow about a billion years ago.
Type A is not stable rock, it’s clay.
“Cohesive soils with an unconfined, compressive strength of 1.5 ton per square foot (tsf) or greater. Examples of cohesive soils are: clay...” Cohesive – like clay 1.5 tsf or greater This is clay; most likely it would be Type A soil. Some art may require interpretation.
When was the last time you were squashed by a giant clay ball?
Clay ball pins Minn. man in trench
Type A soil or not, you need balls to work around clay!
Associated Press – July 9, 2010 MAHNOMEN, Minn.
A Minnesota construction worker is recovering after a large ball of clay pinned him in a trench.
The Mahnomen County sheriff's office says 28-year old Timothy Henneman of Ashby was working on a road construction project Thursday when a ball of clay - about 4 feet in diameter rolled back into the trench and pinned him to the
Downgrade ahead!
Downgrade from Type A if...
The soil is fissured
Some volcanoes can be covered in Type A soil. But, be careful! Lava easily flows through fissures.
This is clay. Type A clay wouldn’t do this.
Downgrade from Type A if...
The soil is subject to vibration from...
Nearby traffic or equipment (or that on site) Anything that causes vibrations.
Downgrade from Type A if...
The soil has been previously disturbed...
Just about any prior activity “disturbs” the soil.
Type B soil: crushed, angular gravel.
“...unconfined compressive strength greater than 0.5 tsf but less than 1.5 tsf.” “...Granular cohesionless soils including: angular gravel (similar to crushed rock)...” “Dry rock that is not stable” Type B soil may be fine to park a car on, but it still requires a protective system.
And, it can be difficult to classify.
Type C soil: just about everything.
“... unconfined, compressive strength of 0.5 tsf or less; or “...gravel, sand, and loamy sand” “Submerged soil” “Submerged rock that is not stable” Also keep in mind the many downgrading factors like previously disturbed, vibration, water, etc. It’s easy to end up as Type C soil.
Just remember this...
Cohesive soil (such as clay) does not crumble and is hard to break apart (even when dry) .
Granular soil (such as crushed rock) has no cohesive strength. It cannot be molded (even when
moist)
.
Soils Analysis
Is a protective system needed?
1926.652(a)(1)
“Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section...”
1926.652(a)(1)
“Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section...”
Are there any exceptions?
Protection is not needed if...
Excavations are made entirely in stable rock .
Cliff wall at Lake Manzoni, Alaska.
Protection is not needed if...
Excavations are less than 5 feet in depth and examination by a competent person provides no indication of a potential cave-in.
A couple feet down.
29 CFR 1926.652(a)(1)
(Requirements for protective systems) There were more willful violations of this standard than for the number two (fall protection) and three (scaffolding – general requirements) areas combined.
(OCTOBER 1 ST 2008 TO SEPTEMBER 30 TH 2009)
Is a protective system needed?
Sloping and Benching
Type C may be simply sloped.
“All simple slope excavations 20 feet or less depth...
in ...shall have a maximum allowable slope of 1 ½ : 1.” ) ( 34 degrees
Type C may be simply sloped.
“All simple slope excavations 20 feet or less depth...
in ...shall have a maximum allowable slope of 1 ½ : 1.” ) ( 34 degrees The blue slope represents 1: 1 (45 degrees)
Type C may be simply sloped.
“All simple slope excavations 20 feet or less depth...
in ...shall have a maximum allowable slope of 1 ½ : 1.” ) ( 34 degrees
Type C may not be benched.