The soil classification and bearing capacity of the soil must be determined before the foundation is constructed and anchored. The soil classification and bearing capacity must be determined by one or more of the following methods, unless the soil bearing capacity is established as permitted in paragraph (f) of this section:
(a) Soil tests. Soil tests that are in accordance with generally accepted engineering practice; or
(b) Soil records. Soil records of the applicable LAHJ; or
(c) Soil classifications and bearing capacities. If the soil class or bearing capacity cannot be determined by test or soil records, but its type can be identified, the soil classification, allowable pressures, and torque values shown in Table to Sec. 3285.202 may be used.
(d) A pocket penetrometer; or
(e) In lieu of determining the soil bearing capacity by use of the methods shown in the table, an allowable pressure of 1,500 psf may be used, unless the site-specific information requires the use of lower values based on soil classification and type.
(f) If the soil appears to be composed of peat, organic clays, or uncompacted fill, or appears to have unusual conditions, a registered professional geologist, registered professional engineer, or registered architect must determine the soil classification and maximum allowable soil bearing capacity.
Table to Sec. 3285.202----------------------------------------------------------------------------------------------------------------
Soil classification--------------------------------------
ASTM D 2487-00 or Allowable soil Blow Torque probe \3\
D 2488-00 Soil description bearing pressure count value \4\ (inch-
Classification (incorporated by (psf) \1\ ASTM D pounds)-
number reference, see 1586-99
Sec. 3285.4)----------------------------------------------------------------------------------------------------------------1................ .................. Rock or hard pan....... 4000+............. ........2................ GW, GP, SW, SP, Sandy gravel and 2000.............. 40+ More than 550.
GM, SM. gravel; very than
dense and/orcemented
sands;coursegravel/
cobbles;preloaded
silts,clays and coral.3................ GC, SC, ML, CL.... Sand; silty sand; 1500.............. 24-39 351-550.
clayey sand;
siltygravel; medium
dense course sands;
sandygravel; and very
stiff silt, sand clays.4A............... CG, MH \2\........ Loose to medium dense 1000.............. 18-23 276-350.
sands; firm to stiff
clays and silts;
alluvial fills.4B............... CH, MH \2\........ Loose sands; firm 1000.............. 12-17 175-275.
clays; alluvial fills.5................ OL, OH, PT........ Uncompacted fill; peat; Refer to 0-11 Less than 175.
organic clays. 3285.202(e).----------------------------------------------------------------------------------------------------------------Notes:\1\ The values provided in this table have not been adjusted for overburden pressure, embedment depth, water
table height, or settlement problems.\2\ For soils classified as CH or MH, without either torque probe values or blow count test results, selected
anchors must be rated for a 4B soil.\3\ The torque test probe is a device for measuring the torque value of soils to assist in evaluating the
holding capacity of the soil in which the ground anchor is placed. The shaft must be of suitable length for
the full depth of the ground anchor.\4\ The torque value is a measure of the load resistance provided by the soil when subject to the turning or
twisting force of the probe.