Page 16 - Tennessee 811 Magazine 2018 Issue 2

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ONION an — sl.oEINc AND EENCHING ’

Tliis ptocedute calls, iitst, tot classitymg the soil, then tetettmg to the cliatts — ; {_ ’ "

and illusttations in the OSHA standattl to detetmine the cottect angle ot the H: V ,
sloping ot benching . l »
Etom the OSHA standatd ; i.

TypeS0i| Angle ofBarlk ‘ H‘ “;
v~.— t, , ., y 4
Stable Rock Vertical wall --j.
Type ASoi| 3/4101 (H to V),or 53 degrees ' T ”"
Type B Soil 1 to 1 (H to V), or 45 degrees
Type C Soil 1 ‘/2 to 1 (H to V), or 34 degrees _ __ -
s , V p A

ONION #2 — TIMBER SHORINC. _

This is a system or wooden walets, ctoss btaces and uptights that suppott — ‘T ‘ ,

the walls or a ttench ot excavation. The OS!-LA standatd specifies the e, — — ~ « \~v

sizes of tmibets, based on the vatious types of soil, the depth or the tiench

ot excavation and the type or timhet used to build the sttuctute (oak ot ‘
Douglas fix’) I

ONION .~:3 —ALL7MlNUM HYDRAULIC SHORINC , c s
Hydtaulic shonng systems have teplaced a lot of timbet shoting. Developed __,_., — V

in calitomia in the late 1950s, tliete ate two main types of hydtaulic shotitig

systems vettical shotes and hotizontal walets. Both employ aluminum , -

tails and hydtaulic cylintlets that apply ptessute to the walls of a ttetich, /V‘ ~
cteatmg an "nxchtng effect” in the atliacent soil that ptevents the walls ttom - 7,

collapsing. _ / '

ONION #4 — TRENCH SHIELDS

Ttench shields ate aluminutn at steel sttuctutes designed to ptotect iitotlcets

by withstanding the totees of a cavein Regardless of the matenal they ate

made or, the ptinciples tot ttencli shields ate the same.

ONION xs — SITE-SPECIFIC ENGINEERED SYSTEMS

Occasionally the chatts in the OSHA stantlatd tot sluping and benching,

ot timbet shontig, as \‘\’eU manufactured systems such as aluminum ‘ W? "W3 °°”_'W>‘ 'W“‘ '“"_W *M}‘*" “""*'“" M
hydtaulic shoting ot ttench shields, ate not apptoptiate Thete may be V'""" “" "‘ ‘” “""'“ “"“”"‘°" "'“"’"’“‘

labsitz conditions ot othet taciots that ptevent the use of all these systems

In these situations, a tegistetetl ptotessional engineer must deslgn a system

specifically rat the lab. The engineet has to be tegisteted in the state whete Tu summatiae:

the system will be used and will have to "stamp" the deslgn Thete ate E 1 . I ‘ d d m d
additional tcquitetnents as well, all ui which ate coveted in the OSHA —" ‘“"‘“3 " P“’*’’“ V T“"‘“ ““ “. °’‘‘‘
Stand“ competent Ectson onsite and following

the cenetal Rzqutmmsnls section ot the
step as — Inspect the Excavzlion OSHA stantlatd, carefully classitying the
The ptttpetly ttained and autlionted competent Eetson tiiust inspect ”?"" ”‘°‘_‘ by ““"““g "‘°“°“"* °>."“"“' "““
Emmim dad m ngomualy and tepeatedly inspecting evety
* Y excavation, you and yuut employees can

- indications or possible cave-ins; Work safely in ttenches and excavations. .
- tailute otptoteciive systems;

- haaatdous atmosphetes; Dlzvld new is Ca-fuuwdcr af Tr('rIz'hSrIf('Iy and

5 l - Y L1 .2 d s

Itispeciions must be conducted ptiut to the statt of Wolk and also as needed eqwivmem, rem" Sm/Ire, and safety fmmmx '0
throughout each shift, attet tainstotms and attet othet potential hazatd- cugrfrrrrcrzawi cxrmnlm, and rmlify wmWi?=-
incteasing events The competent I-etson must also checlt adlncenl ateas and Visit www-Tl'mrhS~_/W-ram or www-
ptotective systems (bctote and duting use) and look always tot indications U"'197'X'U"lid5I1/PW-597"

of possible cave-ins and hazatdous ot potentially hazatdous conditions.

14~ Terlrless::El1 201.8, istaee