Page 81 - Safety Memo

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b. Soil must be classified by a competent person as Type
A, B, or C soil. 1541.1 Appendix A (c)(1)
c. Classification must be based on the results of at least
one visual and at least one manual analysis. 1541.1 No No This is a silt Type B But check Table 1
Appendix A (c)(2)

Table 1 | Site Conditions That Affect Rock/Soil
Slope Stability Is the soil cohesive? Does the soil exhibit: 1) Medium or greater plasticity? 2) Medium or greater toughness? 3) Medium or greater dry strength? 4) Slow reaction during dilatancy test?

Condition Requirement
Soil is fractured/unstable Downgrade to Type B. large enough to be seen with the naked eye? Type A But check Table 1
dry rock. Are at least 50% of the grains (by mass)
Soil is fractured/unstable Downgrade to Type C. ≥ 1.5 tsf
submerged rock.
Soil is cemented (caliche, Classify as Type A.
hardpan, etc.) Type B But check Table 1
Soil is fissured. Downgrade from Type A to Yes This is a clay Estimate the unconfined compressive strength. 0.5 – 1.5 tsf
Type B.
Soil is subject to vibration. Downgrade from Type A to Illustration 5
Type B. No ≤ 0.5 tsf
Soil has been previously Downgrade from Type A to Type C
disturbed. Type B.
Soil is submerged or water Downgrade from Type A to
is freely seeping through the Type C.
sides of the excavation. No This is a sand Type C
Downgrade from Type B to
Type C. mass) larger than 3 /16"
Soil profile is layered with Downgrade from Type A to Yes Are at least 50% of the visible grains (by
the layers dipping into the Type C.
exacavation on a slope of Downgrade from Type B to No Type C
four horizontal or steeper. Is soil submerged or is water freely seeping
Type C. through the side of the excavation?

Start Here Yes Type C Yes This is a gravel Are grains angular? Yes Type B But check Table 1

50 Cal/OSHA Pocket Guide for the Construction Industry | June 2015 Cal/OSHA Pocket Guide for the Construction Industry | June 2015 51