• No results found

Excavation Trenching Shoring

N/A
N/A
Protected

Academic year: 2021

Share "Excavation Trenching Shoring"

Copied!
36
0
0

Loading.... (view fulltext now)

Full text

(1)

Developed by Division of Occupational Safety and

Developed by Division of Occupational Safety and HealthHealth

 August, 2009

 August, 2009

Excavation and Trenching

Excavation and Trenching

The hazards of excavation &

The hazards of excavation &

trenching and how to control them

(2)
(3)

Excavation and Tenching Opeations

Excavation and Tenching Opeations

Course objective:

Course objective:

to provide a basic overview of

to provide a basic overview of

the excavation, trenching and

the excavation, trenching and

shoring regulations located in

shoring regulations located in

Part , chapter !"#$% '(C)

(4)

T

T

o

o

pics

pics

covere

covere

d

d

$

$ *azards of trenching & excavation*azards of trenching & excavation

$

$ +oil classification+oil classification

$

$ Trench protective sstems - shoring & slopingTrench protective sstems - shoring & sloping

$

$ .ther hazard controls.ther hazard controls

$

(5)

'hat is an Excavation/

 An excavation is any peson!"ade cut, cavity,

tench, o depession in the eath#s suface$

 A tench is an excavation

E"ployees "ust be potected fo" cave!in

%hen the excavation is & feet o "oe in

depth$

'ave!in potection is not e(uied %hen)

! Excavations ae "ade entiely in stable oc*+ o 

! They ae less than & feet in depth and exa"ination of the gound by a co"petent peson povides no indication of a potential cave!in$

(6)

% 0atalities 1elated to Excavation (ctivities

in 'ashington +tate

%""2 - !332

Tpes of 4ncidents

+oil collapse 5cave$in6 7 8

+truc9 b machiner 7 

+truc9 b motor vehicle 7 %

+truc9 b falling object 7 %

Electrocution 7 %

(7)

The factors shown in this

illustration can create deadl conditions for wor9ers)

The spoils pile and the

e;uipment being too close to the vertical walls of the

trench are called <surcharge loads= which increase the li9elihood of collapse)

(dditionall, e;uipment

vibration, adverse weather conditions and ground water can change the condition and classification of the soil)

'hat ma9es trenches hazardous/

( <Competent Person= must ta9e all of these factors into consideration and re$evaluate the jobsite periodicall)

(8)

>efinitions

 <Competent person= is someone who:

Can identif existing or predictable hazards in an excavation *as authorit to ta9e corrective actions as necessar

4s familiar with the >.+* excavation standards

4s 9nowledgeable in soil analsis and classification as well as the

erection, use, and precautions for the protective sstem on site

 <1egistered Professional Engineer=51PE6 is:

a person registered as an engineer b the 'ashington +tate >epartment of ?icensing, 4(' Chapter %2)@ 1C'

(9)

This trench is well over A deep, cut into loose sand 5class C soil6, that is sloughing off the trench walls) The spoils pile is a suchaged load$ The shea %eight of the spoils not being set at least 2 feet bac* fo" the vetical face inceases the li*elihood of a cave!in and it adds to the depth of the tench$ f the tench is -. deep and the spoils pile is -. high diectly at the edge, the tench is no% /. deep1 A tench that is . deep could easily beco"e 3!. deep if the spoils pile is on the edge$

(10)

*azardous Trench Example

5conAt)6

 The %eight 4 vibation of the tac*!

hoe also inceases the pobability of a collapse$

 The e"ployees %o*ing in the

tench ae exposed to)

! ovehead ha5ads 6no had hats7, and

! tench collapse %ithout a potective syste"

  t does not appea that safe

access o egess has been povided$8

8 A stai%ay, a"p, ladde o othe safe "eans of egess "ust be located so

%o*es don.t have to tavel "oe than 23 feet lateally in the tench$

(11)

(nother hazardous trench example

eaby heavy e(uip"ent and the spoils pile diectly on the ight edge of the excavation both ceate a suchage load$ The potective yste" in this photo does not extend fa enough up the tench to povide ade(uate potection fo the t%o %o*es in the tench$

(12)

Process for +afe Trench 'or9

 4dentif 9nowledgeable competent person

 Chec9 and verif above and below ground utilit

locations, an adjacent structures or surface encumbrances, and water table

 >etermine soil classification through testing

 Choose the correct protective sstem for soil tpe  Berif protective sstem installation and set$up  Provide safe access

 Compl with re;uirements specified in the

Excavation, Trenching, and +horing regulations)

 Conduct dail inspections prior to the start of wor9,

(13)

0irst: ou must locate utilities before

digging

Go to:

www.callbeforeyoudig.org

or

Call %$233$!$

4tAs 0ree

(14)

Dou are re;uired to to call for utilit locates

and once the locates have been identified

onsite, the emploer must do an exact locate

as specified by:

'(C !"#$%$#5!65c6

:;hen excavation opeations appoach the location of undegound

installations, the exact location of the installations shall be dete"ined by safe and acceptable "eans$<

'h do ou need to do exact utilit locates/

ecause the are rarel spot$on, and older

installations ma not show up on current utilit maps)

(15)

 Controlling heav vehicle surcharge loads

'hat does the $degree angle represent/

4t represents the zone of

influence or affected area) 4n other words, it represents the shear plane 5wea9est area6, at which the excavation or trench wall will fail, and that is wh it should alwas be 9ept clear of heav e;uipment or machiner, and the spoils pile, unless the trench can be properl shored)

(16)

Controlling water accumulation

'ater accumulation in a trench is hazardous because it erodes and changes soilG which means the stabilit of the soil is li9el wea9ened)

Prevent water accumulation b using sump pumps, or create diversion ditches and di9es for natural drainage of streams

interrupted b the excavation or in anticipation of heav

rainwater runoff, or consult with an 1PE)

+pecial supports or shield sstems ma be needed if water accumulates on the trench floor)

(17)

'ater (ccumulation Control +stem

'ater accumulation hazards should be prevented b either using a

special support or shield sstems designed for water drainage issues, or water removal to control the

level of accumulating water, or use of a safet harness and lifeline b wor9ers inside excavation)

'ater controlled through the use of pumps and other e;uipment setups must be monitored b a competent person to ensure proper operation) >iversion ditches, di9es, or other suitable means should be used to prevent surface water or rainwater from entering and accumulating in the excavation)

 A %ate contol syste" that got out of hand1

(18)

Classifing +oils

4t is important to correctl classif soil tpe

before selecting and using a protective sstem)

4n order to classif soil, at least one visual test

and one manual test are re;uired to determine

if the soil is Tpe (, Tpe , or Tpe C)

=ost enginees agee that less than 3> of the soil in ;ashington can be classified as Type A, and as soon as the Type A soil is distubed, it "ust be do%n gaded to a Type ?$

(19)

+oil characteristics

Tpe (:

Hood cohesive soil with a high

compressive strength such as: cla, silt cla, sand cla, cla loam and cemented soils such as caliche, duricrust and hardpan

Tpe :

Cohesive soil with a moderate

compressive strength such as: silt, silt cla, sand cla, cla loam, silt loam, sand loam, angular

gravel 5similar to crushed roc96, an previousl disturbed fissured or soil or subject to vibration

Tpe C:

Cohesive soil with a low compressive strength such as: granular soils including gravel, sand, and loam sand or submerged soil or roc9 that is not stable or soil from which water is freel seeping

(20)

+oil classification

Tpe <(= 

- 0ine grained

- >oesnAt crumble

- *ard to brea9 up when dr - Examples:

I Cla

I *ardpan

I +ilt or sand cla, cla loam

'lay @oa"

'lay

 As "oe oganic "atte, silt and sand 6 togethe *no%n as loa"7 gets "ixed in and as the gains get lage, the classification %ill be degaded to type ?$ As the "ix has less and less clay and oganic "atte in it beco"ing close to pue sand o gavel it

(21)

+oil Classification

Tpe (

Even if soil has high cla content and is plastic when

moist, it cannot be classified as  <Tpe (= if it is:

$fissured,

$has been previousl disturbed, or

$subject to vibration from

heav traffic, etc) This soil is fissued changing the classification fo" A to ?

'lues fo peviously distubed soil) soil discoloation, lac* of vegetation, you dig and discove pipes o so"ething else$ f the %o* odes ae specific to eplacing existing

(22)

+oil classification

Tpe 

- Hranular: coarse grains - ?ittle or no cla content - Crumbles easil when dr - Examples:

I Silt$fine mineral particles in size between cla and sand

I Loam$from fragments of roc9 deposits in water

I Angular gravel$crushed roc9$the angular nature of the individual roc9s provides some resistance to movement

Silty loa"

(23)

+oil Classification

Tpe C *

- Hranular soil: ver coarse - Jinimal cohesion

- Examples:

I +and I Hravel

I ?oam sand

I +ubmerged soil or soil with freel seeping water

I +ubmerged roc9 that is not stable)

Sand

avel

* Tpe C is the most common soil classification in 'ashington)

(24)

Tpes of Protection +stems

I +loping and enching

I +horing +stem

$ Timber, (luminum$*draulic

$ +hield +stem

$ +teel +hield ox, (luminum ox

(25)

'hat are the protective sstem re;uirements/

Fse protective sstems when there is potential

for cave$in for Class (, , and C soils:

- Under 4’ deep if a potential for a cave$in exists - 4’ to 20’  deep

I +loping or enching 5benching is not an option in C soil6 I +hield or +horing

- Over 20’ deep $ protective sstem must be

designed b 1egistered Professional Engineer or approved in manufacturerAs tabulated data

(26)

+loping

+loping is the process of removing soil to

eliminate the chance of a cave in)

The re;uired maximum allowable slope is

determined b the class of soil)

The re;uirements are as follows:

! Bo each foot of tench depth, the atio of slope "easued fo" the tench edge at gound height "ust be)

+oil Tpe ( -

K to % 5@L6

+oil Tpe  -

% to % 5L6

(27)

+horing

+horing is one of the most common used methods of wor9er

protection) 4t is light$ weight, portable and eas to install)

The manufacturer

provides tabulated data with the shoring that

provides the limitations, precautions, re;uired

spacing and proper use)

This photo shows an example of aluminum hdraulic shoring)

(28)

+hields

+hields are manufactured b a number of companies and are designed to protect wor9ers

wor9ing within the confines of the shield)

Chec9 tabulated data for the

maximum allowable depth it can be used) The tabulated data

must accompan the shield when it is being used)

(dditionall, the shield must be designed b a 1egistered

Professional Engineer, be in good condition, and used properl)

(29)

+hields That >onAt Ho (ll

The 'a To The ottom)))

Excavation of material to a level no deeper than ! feet below the bottom of the members of a support sstem is permitted onl if:

$ the sstem is designed to resist the forces

calculated for the full depth of the trench,

$ there are no indications while the trench is open of a possible loss of soil from behind or below the bottom of the support

(30)

1PE$>esigned Protective +stem

( 1egistered Professional Engineer can

design a protection sstem for use on a

specific project)

The 1PE will consider the soil tpe and

conditions as well as other concerns that

might exist at the excavation site)

The sstem must be used as designed b

the 1PE)

Even with an 1PE, the Competent Person

must still perform dail inspections

(31)

.ther +horing Jethod Examples

Just be designed b a registered

(32)

Provide safe entr and exit

( trench that is A or more in depth must have a safe means for wor9ers to get in and out of the trench)

( means of egress is re;uired to be within !A of lateral travel)

The most common method for access is a straight ladder or an extension ladder) 4f a ladder is

used, it must extend a minimum of @A above the landing) The use of step ladders is not permitted)

.ther means could be a stairwa or ramps or other means as designed b a 1PE)

?ocating the method of

(33)

uc9ets of excavators, bac9hoes, etc)

are not to be used as a means of egress)

(34)

=ost 'o""on Tenching Ciolations

o cave$in protective sstem being used when

re;uired b soil classification, depth, and code

Excessive surcharge load 5spoils piles too close

to excavation wall or e;uipment or traffic too

close to excavation operations6

o accessNegress for excavations  feet or

more in depth

(35)

 An E"ploye only %o*ing in an unpotected

excavationtench can be cited by DOSH$

f the e"ploye is %o*ing in the tench alone

6no e"ployees in the tench7 %ithout using a

potective syste", the e"ploye can be cited

since, in the event of a cave!in, you ae

exposing evey e"ployee to cave!in ha5ads if

they u"p into the excavation to atte"pt escue$

(36)

Jore information and training

 .nline Training course:

 4.+* $Trench +afet (wareness

OSHA e!Tool) OSHA 'onstuction eTool) Tenching and Excavation

Oegon OSHA ) :Excavations Safe Gactices< publication) http)%%%$cbs$state$o$usoshapdfpubs2/&$pdf 

http)%%%$lni$%a$gov%ishaulesconstuctionHT=@29!/33I/$ht"

References

Related documents

Leveraging Boeing’s current international operations and supporting development of new

n Percolation rate of water is different in different types of soil.. It is highest in the sandy soil and least in the

!rr &#34; &#34;p p S Sii# #$ $a att&#34; &#34;rree MUHAMMAD IDHAM BIN IDRIS. MUHAMMAD IDHAM BIN IDRIS MUHAMMAD SYHAFIQ AZLAN BIN MUHAMMAD SYHAFIQ

The technology has also been adopted for training  and  assessments  in  the  maritime  sector.  The  mathematical model of a ship created on a computer 

The power of the test depends on the sample size, the magnitude of the standard deviation, the alpha level, and the true difference between the population mean and the

Atmospheres Confined Spaces Test for Contaminants Standing Water Benching, Sloping, Shoring, Shielding.. Scope

Launched in March 2004, BANKSETA’s flagship Letsema Learnership Project will assist stakeholders to meet their Financial Services Charter human resource targets.. The intention

Perhaps our biggest challenge is the lack of central funding. Even if ANKOS were chartered under some legal instrumentality, which presently it is not, central funding would not be