Page 16 - Arkansas 811 Magazine 2019 Issue 3

Pa" “"99: S0" lllasslllcallon “""““’°"“
adly, as many as 400 workers fracture and destabilize soil that was Type c. The cr should also check the
are killed and several thousand initially considered stable. sides ot the excavation tor layered
wo,kE,,. am ,.E,;.,“,.iy ,,.i,,,ad Type A _ Defined as mlmm smlwflh systems, water, utilities, and signs ot
in trenohes and excavations an umnfmd mmpmsive mngth previously disturbed soils The CI’
across the U.S. each year one reason: D‘ 15 mm per mum mm Dr Em“ rt}-N else be v-is-lax-I for svumes 9*
M““Y IMP‘? ‘°‘E*‘ ‘h? ‘’’*‘S*‘‘ °‘ As a practical matter Type A soil is "‘b”‘“““‘
*"°“' Tl“ Pam‘ 0"“ ‘“"“ “’°‘ “‘ "°" also rare because previously disturbed Manual Tests - There are a number
“"‘g}‘.” "’“‘”’*°“ 9'.’ ““d 140, P°“"d*"' soils, or soils subject to vibration ot ditterent manual tests included in
A ‘"5" Y“’‘’‘ "‘ 5°“ “’"‘ ‘”“E}‘ “‘"‘°"‘ trom consrrucriun equipment rmffi: the OSHA standard.
41°00 P““"“""' “" ‘““d‘ ‘S ““ 5”“ A’ railwa s etc are dis ualitiecl as bein
a result, when a trench cave.in occurs, ,.T #2, " "1 ’ 3 The Dry strength, Thread, or Ribbun
there are usually deaths or very serious VP ‘ Tests can be used to determine it a soil
injuries. Type B - Defined as moderately is cohesive or granular.
An important responsibility tor the d':‘:‘T“” TYPE A’ The Thumb I-enetration Test relies
"Cumpztenl Person" (discussed ’ ’ W ’ ' heavily upon the experience of
in part one of this series) is ”Snil Type C - Deiined as the least the person performing the test. ln
Clas~ifl:ntiun.” It is the tirst step in cohesive soils, having an uncontined the Thumti Penetration Test, the
choosing a protective system, and compressive strength less than .5 tons "Competent Person" gathers a handtul
the law requires it. Even it a soils Per square toot This includes wet, ottreshly excavated soil and presses
engineering service has been identitied granular, or loose soils. The best way his/ her thumb into the material. Type
tor a project, the "Competent Person" is to remember Type c is to Ihlnk ot the A soits require a great amount of ettort
still required to classity the soil. "0 standing tor crummy. lt is the to indent the soil. Type B soils can be

°‘ °““"‘““ WP“ “‘ 5"“ 05”-A "' "Competent Person" [CP] is required
concerned with just tour types ‘D Pmum at 12“ M vmal and M I-oclret Penetrometers and shearvanes
_ * _ . can he used to determine the
“able RM" ' DEW“ 3*‘ “““"“‘t "‘““““‘ ‘°"‘ °‘ ‘h“ ‘“‘l’ a roximate uncontined com ressive
°°““ "“‘E"‘;'“.‘t:‘““i’ ‘‘‘l“‘_;““ ‘’*d In Visual Test - To nlake a visual test, sggngth ot soils P ’
excava wi ver ica si es an wi i. . ii . .
remain intact while exposed stable :2; ‘géivlijm There is one method nf soil
rack is extremely rare ln tact, less than ’mm;m in my dump’ is cnhesive classification that the cr can employ
two percent of the soil in the U. s is and h Probably Type A M TYPE B Sm to avoid all these tests l-le/ she can
classified as stable Rock. ln ndditiun, (depmdmg “Pm mm mam)’ SD“ assume the ”wDr.s'2 case" scenario and
the process of excavating with saws, ml flaws M D‘ an mama! bum‘ N classity all soil as Type c. The trenoh
tirealcers, dynamite, etc., will likely granular’ loam M W2‘, and ‘S Pmbably :;:x:;v:::}ni;:i;;h:;‘h:£:§:d,‘n ‘ml
. many contractors and utllllies lake the
7/ position that every soil they wnrk in
is Type c. That helps to simplity the
entire trenching and excavation safety
, ,‘/ A . *‘«.;' process immensely .
Editors Niito This )5 the thud ii/fviir
articles iii this scrlcs tliiit dlsmsscs 5peclflL'
5I('p5 H111! ClJrIl‘YI1L‘l‘aY5 and ullliflfs um
take to hclp insure the siifcty Dffheir
I ‘V »/ Kr’ p?r5DImEl ODWlJH5Iy, this is air D710’!/)('w
iiftliesiiliyect ll is iiiipossinle to priipctly
“ cover the topic Ill ]usI]mAr relnflvely short
articles caiitriictiirs iiiid IAHIJHES iiirolrcd
‘ iii iiiidergroiiiid wiirlr will rieetl adtlitibiitil
tmiiiiiig to insure warkzr sizfcty.
alien. pflllfllmnlfllfv [Sim exmllplcoftl VHIHIH/U Msnlmt en. bl‘ )A«‘v/0rVll£UIOdCN‘1nmll‘§olltypfl
IA . Arkansas B11 Mflgfllme 2019, issae s