HomeMy WebLinkAboutAPA1723 supplUNITED STATES DEPARTMENT OF AGRICULTURE
SOIL CONSERVATION SERVICE
Supplement to
SOIL SURVEY OF FAIRBANKS AREA, ALASKA
September 1963
containing
SOIL INTERPRETATIONS
for
NONAGRICULTURAL PLANNING AND DEVELOPMENT
Soil Conservation Service
April 1974
The soil survey of the Fairbanks Area, Alaska, published in September
1963, included some interpretations of soil properties for use by engineers
and others involved in construction, but emphasized interpretations for
agricultural use of the soils. This supplement contains additional inter-
pretations for use by planners, contractors, engineers, home builders,
and others concerned with nonfarm uses of soils. Detailed descriptions of
the soils and soil maps are in the original report and are not repeated
here.
Among properties of soils that are highly important in engineering
are permeability, strength or bea~ing capacity, compaction characteristics,
drainage condition, shrink-swell potential, particle-size distribution,
plasticity, and reaction. Depth to the water table and to permafrost,
and soil slope are also of considerable importance. These properties,
in various degrees and combinations, affect construction and maintenance
of roads, airstrips, pipelines, foundations for small buildings, embank-
ments and dams, and systems for disposal of sewage and refuse.
The information in this supplement can be helpful to those who--
1. Select potential residential, industrial, commercial, and recre-
ational areas.
2. Evaluate alternate routes for roads, pipelines, and underground
cables.
3. Seek sources of gravel or sand.
4. Correlate performance of structures already built with properties
of the kinds of soil on which they are built, for the purpose of
predicting performance of structures on the same or similar kinds
of soil in other locations.
5. Predict the trafficability of soils for off-road movement of
vehicles and construction equipment.
6. Develop preliminary estimates pertinent to construction in a
particular area.
Much of the basic information on which the interpretations are based
is presented in Table 1. This table of estimated physical properties is
revised from the comparable table in the original report to reflect
more recent information and new national standards for presentation of
information of this kind. Interpretations for various engineering uses
of soils are presented in Table 2. From the information given in the
original publication and this supplement, along with the soil map, it is
possible to make interpretations in addition to those given in Table 2
and to make other useful maps.
This information, however, does not eliminate the need for further
investigations at sites selected for engineering works, especially
works that involve heavy loads or that require excavations to depths
greater than shown in the tables. Also, inspection of the sites, espe-
cially the small ones, is needed because the delineated areas of a given
mapping unit may contain small areas of other kinds of soil that have
strongly contrasting properties and different suitabilities or limitations
for soil engineering.
- 2 -
How to Use this Report
The first step in using this supplement is to determine, from the
soil map in the original report, the soil series and phases included in
the area of interest and to read the descriptions of the soils in that
report. It is then only necessary to consult Table 2 in this supplement
to determine the degree of limitation for any specific use or uses. The
table also indicates the principal reasons for any adverse rating. The
criteria used in making assessments of soil limitations are discussed in
this supplement. It should be noted that, in many cases, even severe
limitations can be overcome by appropriate design of structure or instal-
lation, though costs of construction and maintenance may be considerably
higher than average. For example, flood proofing of structures may over-
come many of the hazards of building on flood plains.
For planners and others concerned with the entire soil survey area,
it is possible to depict the location of soils that are suitable {or
impractical) for a particular use by coloring or otherwise marking areas
on the soil map according to their degree of limitation. For example, a
list of mapping ~mits and their symbols can be made of soils that have
slight limitations for sanitary landfills. All areas with the listed
symbols on the soil map can then be colored green. Similar lists can be
made of soils wi t:h moderate and severe limitations for this use, and cor-
responding areas can be colored yellow and red. The completed colored map
will then indicat:e at a glance where sanitary landfills are easily
developed, where they are possible if moderate limitations are overcome,
and where they are impractical because of sev-:re limitations. Similar
- 3 -
coloring or marking schemes are possible for any other potential use
or combination of uses.
It is important to recognize that, because of the map scale used in
most surveys, very small soil areas cannot be shown. Many mapped areas,
therefore, include spots of soils of some other kind that are too small
to delineate separately. Also, in this survey soils were examined only
to a depth of 40 to 60 inches. Though the properties of material beneath
this ~epth can commonly be inferred from the soil description, no actual
observations were made. The soil map is a guide to probable soil condi-
tions at any point, but it cannot be used as a substitute for detailed
investigations at the site of any proposed construction.
Engineering Soil Classification Systems
Two systems most commonly used in classifying samples of soils for
engineering purposes are the Unified system used by the Soil Conservation
Service, Department of Defense (3), and other agencies, and the system
adopted by the American Association of State Highway Officials (1).
The Unified system is used to classify soils according to those prop-
erties that affect use as a construction material for purposes other
than highway construction and maintenance, and as a foundation material.
In this system soils are classified according to particle-size distrib-
ution, plasticity, and organic matter content and are grouped in 15 classes.
There are eight classes of coarse-grained soils, identified as GW, GP,
GM, GC, SW, SP, SM, and SC; six classes of fine-grained soils, identified
as ML, CL, OL, MH, CH, and OH; and one class of highly organic soils,
- 4 -
•
identified as Pt. Soils with properties intermediate between two classes
are designated by a hyphenated symbol; for example, CL-ML.
The AASHO system is used primarily to classify soils according to
properties that are important in highway construction and maintenance.
There are seven basic groups in this system, A-1 through A-7, defined by
grain-size distribution, liquid limit, and plasticity index. In group
A-1 are gravelly soils of high bearing strength, or the best soils for
subgrades. At the other extreme, in group A-7, are clayey soils that are
poor for subgrades. An additional group, A-8, is used to identify organic
soils.
Both Unified and AASHO classifications are given in Table 1 for all
soils mapped in the Fairbanks area. More detailed explanations of both
systems are given in the PCA Soil Primer (2) and in standard textbooks
on soil mechanics.
In addition to the engineering classifications, Table 1 gives soil
textures according to the classification of the u.s. Department of Agri-
culture. The u.s.D.A. texture is determined by the relative proportions
of sand, silt, and clay in soil material that passes the No. 10 (2 mm)
sieve. If the soil contains gravel or other particles coarser than 2 mm,
or large quantities of organic matter, a modifier such as "gravelly" or
"mucky" is added to the textural class name. Definitions of some of the
terms used in the U.S.D.A. textural classification are given in the
original Fairbanks Area soil survey report.
- 5 -
Soil Properties Significant in Engineering
Estimates of several properties of soils that are significant in
engineering are given in Table 1. These estimates are made for typical
soil profiles, by layers sufficiently contrasting so that there are
important engineering differences. They are based on field observations
made in the course of mapping, on test data for these and similar soils,
and on experience with similar soils in other areas.
Some of the properties estimated in Table 1 are discussed below.
Depth to seasonally high water table refers to distance from the sur-
face of the mineral soil to the highest level reached by ground water in
most years before clearing of the native vegetation. Temporary wetness
during the spring thaw is not considered. In soils with free water perched
above permafrost, the water table may be lower after the surface mat of
vegetation is removed and the permafrost table drops.
Depth to the permafrost table refers to distance from the surface of
the mineral soil to the upper level of perennially frozen soil--that is,
soil in which the temperature does not exceed 32°F at any time during
the year--under the native vegetation. When the vegetation and the mat
of organic material on the soil surface is removed, the permafrost table
recedes to much greater depths.
Liquid limit and plasticity index are measures of the effect of
water on the strength and consistence of soil material. As the moisture
content of a fine-grained soil is increased from a dry state, the soil
at a particular moisture percentage changes from a noncohesive to a
moldable or plastic state. This is the plastic limit. At a still higher
- 6 -
•
moisture percentage the soil becomes sufficiently fluid to flow when
lightly jarred. This is the liquid limit. The numerical difference
between the plastic and liquid limits is called the plasticity index,
and indicates the magnitude of the range of moisture contents over which
the soil is in a plastic condition.
Permeability is the property of a soil that enables it to transmit
water or air. The estimates in Table 2 are based largely on field obser-
vations of soil texture and structure, and are for soils that have not
been compacted. For wet or frozen soils, the permeability is that to
be expected after thawing of permafrost and removal of free water.
Available water caracity is defined as the difference between the
amoant of water the soil can hold against the force of gravity and the
amount it contains at the wilting point of most crop plants. It represents
the ability of the soil to furnish water for plants. In poorly drained
soils, water in excess of this amount is normally present before drainage.
Reaction is the degree of acidity of alkalinity of a soil, expressed
as pH values.
Shrink-swell rotential is the relative change in volume of soil
material to be expected with changes in moisture content; that is, the
extent to which the soil shrinks as it dries or swells as it is moistened.
A high shrink-swell potential'indicates a hazard to maintenance of struc-
tures built in, on, or with soil having this rating.
Soil Limitation and Suitability Ratings
For most purposes, three degrees of limi~ation or suitability are
recognized in Table 2. These are defined as follows:
- 7 -
Slight or Good -Soils are relatively free of limitations for the
intended use, or the limitations are easy to overcome.
Moderate or Fair -Soils have some limitations for the intended use
because of slope, texture, depth, wetness, flooding or some other
property or environmental consideration. Normally, these limitations
can be overcome by good planning, design, or management.
Severe or Poor -Soils with limitations that are difficult or not
economically feasible to overcome. Reasons for this rating include
steep slopes, flooding, and stoniness. In some cases, however, the
soils may be made suitable for the intended purpose by major recla-
mation work or careful design.
A rating of unsuited is used only in evaluating soils as sources
of sand or gravel.
Roadfill -Ratings for this purpose indicate how well a soil is
expected to perform after it is removed from its original location and
placed as a subgrade material elsewhere. They also are intended to evalu-
ate soil characteristics that influence the difficulty of excavation of
the soil. It is assumed, in the suitability ratings, that the whole
soil to a depth of 5 or 6 feet will be thoroughly mixed and will be used
in embankments that are less than 6 feet high. For higher embankments,
roadfill requirements are more stringent.
Soils that are considered to be good sources of roadfill are at
least moderately well drained, and dominantly sandy or gravelly with low
plasticity, low susceptibility to frost action, and low shrink-swell
potential. They have only a few large stones and have slopes of less than
- 8 -
15 percent. Poor sources of roadfill are soils that are clayey or plastic,
highly organic, highly susceptible to frost action, very stony, or poorly
drained, or that have slopes steeper than 30 percent. Fair sources have
intermediate properties.
Gravel -Soils are considered to be suitable sources of gravel if
they are underlain by or contain a layer at least 3 feet thick and the
upper limit of this layer is no more than 6 feet deep. In soils with a
rating of good, at least 50 percent of the material in the gravelly layer
is coarser than 0.7 mm (approximately .03 inch), a significant portion of
this is coarser than 4.8 mm (approximately 0.2 inch), and less than 5
percent of the material is silt or clay. A rating of poor is given where
silt and clay comprise more than 12 percent of the soil. Soils that
contain less than 25 percent gravel are rated as unsuited.
Sand -Suitability ratings for sand are similar to those for gravel,
except that sand and gravel combined must make up at least 50 percent of
the coarse-textured layer and significant portion of the layer must be
of sand size (0.7 to 4.8 mm, or approximately 0.03 to 0.2 inch).
Topsoil-The term "topsoil", as used here, refers to soil material
used to cover surfaces that are barren as a result of construction
activities in order to create more suitable conditions for the establish-
ment and maintenance of vegetation. The properties considered in rating
soils as sources of topsoil are those that affect ease of handling and
suitability as a seedbed for a new planting. Also considered are features
that determine the difficulty of excavating and of reclaiming the site
after excavation.
-9 -
Soils that are good sources of topsoil have more than 16 inches of
loamy, friable material, less than 3 percent by volume of gravel or stones,
slopes of 7 percent or less, and are better than poorly drained. Poor
soils are sands or clays, are less than 8 inches thick.over unsuitable
material, have more than 15 percent gravel or stones, have slopes steeper
than 12 percent, or are poorly drained.
Seftic tank absorption fields -These are soil absorption systems
for sewage disposal, consisting of subsurface tile systems laid out in
such a way that effluent from the septic tank is distributed with reasonable
uniformity into the natural soil. Criteria used for rating soils for this
purpose are based on their ability to absorb effluent.· The portion of the
soil that is rated is that which lies at and below the depth of the tile
line. Factors that are considered are soil permeability, depth to imper-
vious or slowly permeable layers, seasonal ground water levels, flooding,
and slope.
Soils with slight limitations are those with permeability rate of
more than 1 inch per hour (but see below), the water table and any imper-
vious layer at least 4 feet below the tile level, and no permafrost.
They may not be subject to flooding, and slopes must be 7 percent or less.
For ease of construction, they should be free of large stones and boulders.
Some sandy or very gravelly soils are so porous that unfiltered raw sewage
may pass through them and contaminate the ground water or nearby lakes and
streams. Although such soils are rated as having slight limitations for
septic tank absorption fields, this hazard must be considered before in-
stallation.
-10 -
Soils are considered to have severe limitations if permeability is
less than 0.6 inches per hour, the water table or an impervious layer is
less than 2 feet below the tile line, slopes are steeper than 12 percent,
flooding is likely, or if they are perennially frozen at some depth.
Sewage lagoons -Sewage lagoons--constructed shallow ponds used to
hold sewage for the time required for bacterial decomposition--require
soils that are capable of holding water with minimum seepage and contam-
ination of ground or surface water. Factors that are important in rating
soils for this use are soil texture, organic matter content, permeability,
depth to the water table, sesceptibility to flooding, and permafrost.
Soils with slight limitations are those with a deep water table,
a permeability rate slower than 0.6 inches per hour, and a slope of 3
percent or less. For proper compaction, the soils should contain few
large stones and the organic matter content should be less than 2 percent.
They should have no permafrost and should never flood. Severe limitations
exist where the water table is less than 40 inches deep, permeability is
greater than 2 inches per hour, slopes are steeper than 7 percent, or
organic matter content is higher than 15 percent. All very stony soils,
soils subject to flooding, and soils with permafrost are also considered
to have severe limitations.
Sanitary landfill (trench type) -A trench-type sanitary landfill
is an excavated trench in which refuse is buried daily with a layer of
soil material at least 6 inches thick. The material used for the daily
cover is the soil excavated in digging the trench. Because the final cover
should be material that is favorable for the growth of plants, the original
-ll -
surface layer of the soil should be set aside for this final blanketing
of the fill. Slope is also important because it affects both the amount
of earthwork needed to provide access to the landfill and the.disposal of
surface water, including that from adjacent higher elevations.
Soils with slight limitations have a water table deeper than 6 feet,
permeability of 2 inches per hour or lees, slopes of less than 12 percent,
medium texture, and few stones. They have no permafrost and are not subject
to flooding. Limitations are considered severe if a soil is poorly drained,
underlain by permafrost, subject to flooding, very sandy, clayey, or stony,
or if slopes are steeper than 30 percent.
Sanitary landfills {area t~e) -In an area-type sanitary landfill.
refuse is placed on the surface of the soil in successive layers. Daily
and final cover material generally is obtained from another site. Ratings
of soils for this use are generally .similar to those for trench-type
sanitary fills except that soil texture and stoniness are less important
because no extensive earthwork is involved.
Soils with slight limitations have a water table deeper than 5 feet,
permeability of 2 inches per hour or less, and slopes of less than 7 percent.
They are not subject to flooding. Severe limitations are shallow water
tables or poor drainage, permeability rates in excess of 2 inches per hour,
slopes greater than 12 percent, and occasional or frequent flooding.
Daily cover material for area-type sanitary landfills -The suitability
ratings of a soil for use as cover material for landfills is based primarily
on properties that affect its workability, or ease of digging, moving, and
spreading, and its acceptability as a borrow site. Problems in reclamation
-12 -
of the site, including revegetation and erosion control, are important
considerations.
Soils that are rated good for this use are medium-textured and easily
worked, not gravelly or stony, more than 40 inches thick over unsuitable
material, and have slopes of 7 percent or less. Poor soils include those
with clay or sand textures, thick organic layers, depths of less than 20
inches over unsuitable material, more than 35% gravel, or many large stones,
slopes steeper than 12 percent, or poor drainage.
Shallow excavations -The ratings for shallow excavations--those that
require digging or trenching to depths no greater than 5 or 6 feet--are
based on factors that influence ease of digging, maneuverability of
machinery, and stability of the completed excavation. Among these are soil
texture and stoniness, permafrost, slope, soil drainage and depth to the
water table, and flooding.
Soils with slight limitations are deep, medium textured, free of stones,
and well-drained. They have slopes of 7 percent or less, and are not
subject to flooding. Soils are considered to have severe limitations if
they are either dominantly stony or gravelly, poorly drained with water
tables shallower than 30 inches, underlain by ice-rich permafrost, subject
to flooding, or have slopes steeper than 12 percent.
Dwellings and small commercial buildings ~ Dwellings are defined as
single-family structures with no more than three stories. They may or
may not have basements. The emphasis in rating soils is on properties
that affect stability of foundations, ease of excavation, installation of
underground utility lines, and utility of the structure after construction.
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These include soil texture and stoniness, permafrost, slope, soil drainage
and depth to the water table, potential frost action, and susceptibility
to flooding.
Soils with slight limitations are deep and free of stones, well-
drained, not susceptible to expansion and contraction as a result of frost
action or swelling clays, and not subject to flooding. They have slopes
of 7 percent or less and are underlain by neither ice-rich permafrost or
deeply buried masses of ice. Severe limitations are poor drainage, a
water table shallower than 30 inches, high susceptibility to frost action,
potential flooding, slopes steeper than 12 percent, and the presence of
permafrost or buried masses of clear ice that can cause pitting or uneven
subsidence below the foundation.
Limitations for dwellings without basements are essentially the same
as for those with basements except that the hazard of frost action is of
greater importance in that footings may not be as deep. For small com-
mercial buildings, slope is of greater importance than for dwellings.
Soils with slopes of 3 to 7 percent are considered to have moderate
limitations. Slopes greater than 7 percent are severely limiting for
those structures.
Local roads and streets -Ratings apply to the use of soils for con-
struction and maintenance of local roads and streets with all-weather
surfacing. The ratings are not intended to evaluate the suitability of
soils for major highways, and in no case can they substitute for detailed
investigation before actual construction.
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Roa~s commonly consist of (l) the subgrade, or the underlying local
soil material, (2) the base material placed above the subgrade during
construction, and (3) the road pavement. Except for the pavement, local
roads normally utilize materials from soils in the immediate vicinity,
and cuts and fills are generally less than 6 feet thick. The factors used
in the ratings are soil drainage, texture and stoniness, slope, suscep-
tibility to frost action, and frequency of flooding.
Soils with slight limitations are at least moderately well drained,
have few large stones, have little potential for frost action, and are
free of permafrost. They are not subject to flooding and have slopes of
7 percent or less. Soils are considered to have severe limitations if
they ·are poorly drained, made up of organic materials, underlain by ice-
rich permafrost or buried masses of ice, highly susceptible to frost action,
very stony, or if they are subject to frequent flooding or have slopes
steeper than 12 percent.
Picnic areas -Picnic areas are attractive natural or landscaped
tracts used primarily for preparing meals and eating outdoors. These
areas are subject to heavy foot traffic, but most vehicular traffic is
confined to access roads.
Soils with slight limitations for this use are at least moderately
well drained, have neither excessively clayey nor sandy surface textures,
are free of flooding during the season of use, have slopes of 7 percent
or less, and are relatively free of stones. Those with severe limitations
are poorly drained, have clay or sand surface layers, are subject to
frequent flooding, have slopes steeper than 12 percent, or are stony.
-15 -
Playgrounds -Playgrounds are areas that are used intensively for
organized games such as baseball or football. Soils suitable for this use
need to be able to withstand intensive foot traffic, and should require
little grading and leveling.
Soils with slight limitations are at least moderately well drained,
are not subject to flooding, have loamy ~extures, and have permeability
rates greater than 0.6 inches/hour. Slopes may not exceed 3 percent,
and the soils must be essentially free of stones. Severe limitations are
poor drainage, frequent flooding, permeability of less than .06 inches/
hour, very clayey or sandy surface textures, slopes greater than 7 percent,
and coarse fragments covering more than 20 percent of the surface.
Pond reservoir areas -Soils over which water is impounded behind
a dam or embankment must have low seepage rates. This is related to their
permeability and to other soil features, such as subsurface ice masses
subject to melting, that may result in loss of water through the soil.
Soils are not rated for this purpose, but those characteristics that
may adversely affect use as a reservoir area are listed. These include
rapid permeability, presence of permafrost or isolated buried ice masses,
susceptibility to piping (underground tunneling) or pitting, steep slopes
which can reduce the storage potential of the area, and high susceptibi-
lity to erosion.
Embankments( dikes, and levees -Earthfills intended to contain or
hold back water require soil material that is stable after compaction and
that is resistant to seepage. Soil properties that adversely affect use
for this purpose are low shear strength, high permeability after compac-
-16 -
tion, susceptibility to piping, and poor compaction characteristics.
The presence of stones or organic material in a soil are among factors
that are unfavorable.
No ratings are given in Table 2 for this purpose, but the principal
unfavorable features are listed for each soil.
Corrosivit1 -Structural materials, such as metal or concrete,
corrode when buried in soil. The corrosivity potential is different for
different soils and for different materials. In this report, soils are
rated according to potential corrosivity of untreated steel and ordinary
concrete. Protective coatings in the case of steel and special cements
and manufacturing methods in the case of concrete may b.e used to reduce
the rate of corrosion.
Corrosion of steel in soils is a physical-biochemical process that
converts iron into soluble forms. Some of the factors that influence
this process are soil moisture content, electrical conductivity of the
soil solution, degree of soil acidity, oxygen concentration in the soil,
and the activity of organisms capable of causing oxidation-reduction
reactions. The potential corrosivity of soil for untreated steel pipe
is commonly determined by measurements of electrical resistivity, soil
acidity, and soil texture, and by evaluation of fluctuations of the water
table. No single measure is adequate to determine potential corrosivity.
Soils with low potential generally are well drained except that sandy soils
may be somewhat poorly (imperfectly) drained, are moderately to rapidly
permeable, have pH values higher than 6.0, and have an electrical resis-
tivity when saturated of more than 5000 ohms/em. Soils with high corro-
sion potential generally are either fine-textured or are somewhat poorly
-17 -
or poorly drained, have pH values of 5.0 or less, or resistivity of less
than 1500 ohms/em. Soils with textural stratification usually have a
higher corrosion potential than soils with uniform textures throughout
the profile. Similarly, the potential is higher at the boundary between
different soils. Organic (peat) soils with fluctuating water tables
generally have high corrosion potential; those with water tables at the
surface throughout the year are generally rated as having moderate cor-
rosivit¥ for steel pipe.
The rate of deterioration of concrete buried in soil depends on
soil texture, soil acidity, and the amount of soluble sulfates in the soil.
Soils with low corrosion potential generally are those with pH values of
6.0 or higher and less than 1000 parts per million of soluble sulfates.
Those with high corrosivity generally have pH values of 5.0 or less and
more than 2000 parts per million of sulfates. In general, coarse-textured
soils are more corrosive than medium-or fine-textured soils.
Construction of buildings, paving, fill and compaction, and additions
to the surface that alter soil permeability can increase the corrosion
probability. Any mechanical agitation or excavation that results in
aeration and nonuniform mixing of soil layers of different textures
may also accelerate the rate of corrosion.
-18 -
References Cited
1. American Association of State Highway Officials. 1961. Standard
Specifications for Highway Materials and Methods of Sampling and
Testing. Ed. 8, 2 v., illus.
2. Portland Cement Association. 1962. PCA Soil Primer, 52 pp. and
charts. Chicago, Ill.
3. u.s. Department of Defense. 1968. Unified Soil Classification System
for Roads, Airfields, Embankments, and Foundations. MIL-STD-619B,
30 pp., illus.
Table 1. Brief description of soils and their estimated physical properties
Sym-
bol
on
map
Ad
Br
Ch
EsD
EsE
EsF
FaA
FaB
FaC
FaD
FaE
FaF
FmB
FmC
FmD
FmE
FmF
GmB
GmC
GmD
GmE
GmF
Depth to
Perma-
frost
table
Soil name
season-
ally
high
water
table
(feet) (feet)
Alluvial land
Bradway very fine sandy
loam
Chena very fine sandy
loam
Ester silt loam, 12 to
20 percent slopes
Ester silt loam, 20 to
30 percent slopes
Ester silt loam, 30 to
45
0
3
loam, 7
slopes
loam, 12
to 20 percent slopes
0-1
0-1
>6
0-1
Deep
Fairbanks silt loam, 20 Deep
to 30 percent slopes
Fairbanks silt loam, 30
to 45
loam, Deep
moderately deep, 3 to
7 percent slopes
Fairbanks silt loam,
moderately deep, 7 to
12 percent slopes
Fairbanks silt loam,
moderately deep, 12 to
20 percent slopes
Fairbanks silt loam
moderately deep, 20 to
30 percent slopes
Fairbanks silt loam,
moderately deep, 30 to
45 ercent slo es
Gilmore silt loam, 3 to Deep
7 percent slopes
Gilmore silt loam, 7 to
12 percent slopes
Gilmore silt loam, 12 to
20 percent slopes
Gilmore silt loam, 20 to
30 percent slopes
Gilmore silt loam, 30 to
45
None
None
<1
None
None
None
None
Description of soil
and site
Depth
from
surface
(typical
profile)
(inches)
Thin silty mantle over 0-60
rounded alluvial
gravel; frequently
flooded
Poorly drained very
fine sandy soils of
flood plains; perma-
frost
Excessively drained
very shallow soils
over rounded alluvial
gravel
0-2
2-40
0-7
7-40
Grain-size distribution
Percent Percent of material less
coarser than 3 inches passing sieve
Soil Classification than 3 No, 4 No. 10 No. 40 No. 200 ;;U;::S:;:D::A-::T:-e-::x-::t-=:ur;.::.:e:.:......:::.:~U:=n~i~f~i:.::e:.::;d~='=AA"':"":S:o::H:-:0:----inches (4. 7mm) (2.0mm) (0.42mm) (0.074mm)
Very gravelly
sand
GW or GP
Mucky silt loam OL
Very fine sandy ML
loam with lenses
of silt loam and
fine sand
Stratified silt
loam, very fine
sandy loam, and
fine sand
Very gravelly
sand
SM or ML
GW or GP
A-1 15-40
A-5 0
A-4 0
A-4 0
A-1 15-40
25-45 25-40 15-25 0-5
;wo 100 95-100 60-70
100 95-100 90-100 50-60
100 95-100 85-95 40-70
25-45 25-40 15-25 o-5
Liquid
Limit
Plasti-
city
index
NP
NP
NP
NP
NP
Permea-
bility
(inches/
hour)
6.0-20
0.6-2.0
0,6-2,0
0.6-2.0
6.0-20
Available
water
capacity
in./in.
of soil
.02-.04
.20-.25
.12-.16
,12-.16
.02-.04
Reaction Shrink-swell
pH values potential
6.1-6.5 Low
6.1-6.5 Low
6.1-7.8 Low
5.1-6.5 Low
6.1-6.5 Low
Poorly drained, shallow~o~-~l~0~-7.S~i~l~t~l~o~am~~---~ML~,~C~L~-~ML~-~A~-~4~o~r~A~-~5~0~-;l~0~--9~0~-~1~0~0~~8~0~-~9~0~--7~5~-~8~5~--7~0~-~8~0~----2~5~-~4~5--~2~-~l~0~----0~.6~-~2~.o~--~·~2*5-~,~30~--4~.~5--75~.~5-~Lo~w~--------
silty soils over shat-10-30 Very gravelly GM or A-1 45-55 10-35 10-30 10-25 5-20 NP 0.2-0,6 .03-.05 5.6-6.0 Low
tered bedrock; occurs sandy loam and GP-GM
on north slopes very gravelly
silt loam
Well-drained, deep 0-40
silty soils of uplands
Well-drained, deep 0-40
silty soils of uplands
Well-drained, moder-0-25
ately deep silty soils
of uplands 25-40
Well-drained shallow 0-17
silty soils of uplands
17-40
Silt loam of
silt
Silt loam or
silt
Silt loam or
silt
Very gravelly
sandy loam and
very gravelly
silt loam
Silt loam or
silt
Very gravelly
sandy loam and
very gravelly
silt loam
ML or
CL-ML
ML or
CL-ML
ML or
CL-ML
GM or
GP-GM
ML or
CL-ML
GM or
GP-GM
A-4
A-4
A-4
A-1
A-4
A-1
0 100 95-100
0 100 95-100
0 100 95-100
45-55 10-35 10-30
0 100 95-100
45-55 10-35 10-30
90-100 85-100 25-40 2-10 0,6-2,0 ,25-.30 5.6-6.5 Low
90-100 85-100 25-40 2-10 0.6-2.0 .25-.30 5.6-6.5 Low
90-100 85-100 25-40 2-10 0.6-2.0 ,25-.30 5,6-6,5 Low
10-25 5-20 NP 0.2-0,6 .05-.10 6.1-6.5 Low
90-100 85-100 25-40 2-10 0.6-2.0 • 25-.30 5.6-6.5 Low
10-25 5-20 NP 0.2-0.6 .05-.10 6.1-6.5 Low
Table 1. Brief description of soils and their estimated physical properties (Continued)
Depth to
season-
ally
high
water
table
(feet)
Depth
from
surface
Grain-size distribution
Sym-
bol
on
map
Perma-
frost
table
(feet)
(typical
profile)
(inc:h.es)
Percent Percent of material less
coarser than 3 inches passing sieve
Soil name
Description of soil
and site
~~~~~S~o~i~l~C~l~a~s~s~i~f~i~c~a~t~i~o~n~~~-----than 3 No. 4 No. 10 No. 40 No. 200
USDA Texture Unified AASHO inches (4,?mm) (2,0mml (0.42mm) (0.074mm)
GrB
GrC
GrD
GrE
GrF
GtA
GtB
GtC
Me
MnA
MnB
MnC
Sc
Sm
Ss
SuB
sue
SuD
Ta
Gilmore silt loam,
very shallow, 3 to 7
percent slopes
Gilmore silt loam,
very shallow, 7 to 12
percent slopes
Gilmore silt loam,
very shallow, 12 to
20 percent slopes
Gilmore silt loam,
very shallow, 20 to 30
percent slopes
Gilmore silt loam,
very shallow, 30 to 45
ercent slo es
Goldstream silt loam, 0
to 3 percent slopes
Goldstream silt loam, 3
to 7 percent slopes
Goldstream silt loam, 7
to 12
Mine tailings
Minto silt loam, o to 3
percent slopes
Minto silt loam, 3 to 7
percent slopes
Minto silt loam, 7 to 12
rcent slo es
Deep
Q-1
0-1
Deep
3-5
Salchaket very fine Deep
sandy loam
Salchaket very fine Deep
sandy lo", moderate-
ly deep -
Salchaket very fine 21 sandy loam, shallow =-
Saulich silt loam, 3 to 0-1
to 7 percent slopes
Saulich silt loam, 7 to
12 percent slopes
Saulich silt loam, 12 to
20 ercent slo es
None
1-2
2-3
Well-drained, very
shallow silty soils of
uplands
Poorly drained silty
soils of flood plains
and upland valleys
Very poorly drained
eat soils'
0-8
8-30
4-30
0-50
Deep Coarse angular gravel 0-60
Silt loam or
silt
Very gravelly
sandy loam and
very gravelly
silt loam
3ilt loam
Silt loam
Peat
ML or
CL-ML
GM or
GP-GM
'OL
ML
Pt
:;w or GP
A-4 0
A-1 45-55
_\-5 or A-4 o
A-4 or A-5 0
A-8
A-1 70-80
Variable, Moderately well drained, 0-40 Silt loam or ML or
CL-ML
A-4 0
discon-deep silty soils on foot-silt
tinuous slopes
None
None
1-3
2-4
Well-drained, deep 0-13
stratified sandy loam,
fine sand, and silt 13-40
loam1 substratum of
very gravelly sand
Well-drained, moder-0-26
ately deep and shallow
stratified soils over
very gravelly sand.
26-40
Poorly drained, deep 0-30
silty soils over bed-
rock
Somewhat poorly drained 0-40
deep silty soils of
flood lains
Very fine sandy ML A-4 0
loam
Stratified fine SM or ML A-4 0
sand, fine sandy
loam, and fine
silt loam
Stratified very SM or ML A-4 0
fine sandy loam,
silt loam, and
fine sand
Very gravelly GW or GP A-1 15-40
sand
Silt loam ML A-4 or A-5 0
Silt loam ML A-4 or A-5 0
!/ Fairbanks silt loam, moderately deep, is now classified as Steese silt loam. The original name is retained in this
supplement
Moderately deep and shallow phases of Salchaket very fine sandy loam are now classified as phases of Jarvis very
fine sandy loam. The original name is retained in this supplement.
90-100 80-95 75-90 70-85
10-35 10-30 10-25 5-20
100 95-100 90-100 ao-100
100 95-100 90-100 80-100
5-30 0-20 0-5 0
100 95-100 90-100 85-100
100 95-100 90-100 75-100
100 90-100 85-100 40-70
100 90-100 85-100 40-70
25-45 .25-40 15-25 0-5
100 95-100 90-100 85-95
100 100 95-100 90-100
Liquid
Limit
25-40
30-50
30-50
25-40
Plasti-
city
index
2-10
NP
NP
0-10
NP
2-10
NP
NP
NP
NP
30-50 3-10
30-65 5-10
Permea-
bility
(inches/
hour)
0,6-2,0
0.2-0.6
0.6-2,0
0.6-2.0
6.0-20
0.6-2.0
0,6-2.0
0.6-2.0
0.6-2.0
6,0-20
0,6-2.0
0,6-2.0
Available
water
capacity
in./in.
of soil
.25-.30
,05-.10
.25-.30
.25-.30
.02-.04
.25-.30
.18-.23
.12-.16
.12-.16
.02-.04
.25-.30
.25-.30
Reaction Shrink-swell
pH values potential
5,6-6.5 Low
6.1-6.5 Low
4.5-5.5 Low
5.1-5.5 Low
4.0-5.0
Low
5.o-7.8 Low
5.1-6,0 Low
5,6-6,5 Low
5.1-6,5 LOW
6.1-6,5 Low
6,1-6,5 LoW
6.1-7.3 Low
Table 2. Interpretations of engineering properties of soils.
Soil series
and map
symbol(s)
Alluvial land
(Ad)
Bradway (Br)
Chena (Ch)
Ester (EsD,
EsE,EsF)
Suscepti-
bility
to frost
action
High
Low
High
Degree of limitation rating for--
Suitability as source of Septic tank Sanitary ----'===:.;:s:-=a:.:n=-d::-<-a-n;:.:;d.....::.::..:==_:;~----absorption Site for landfill
Road fill gravel Topsoil
Poor-WET Good Poor-SST
Poor-WET, Unsuited Poor-WET
FST
Good Good Poor-THN,SST
Poor-THN, Sand; Poor-THN,LST
LST Unsuited
Gravel;
Poor-FIN
fields sewage lagoon. (trench type)
Severe-WET
Severe-WET,
FLD
Severe-FLO
Severe-LST,
PFT
Severe-WET,
PCR
Severe-FLD,
PFT
Severe-FLD,
PCR
Severe-LST,
STP
Severe-WET,
FLD
Severe-WET,
FLD
Severe-FLO,
PCR
Severe-PFT,
BDR
Sanitary
landfill
(area type)
Severe-WET,
FLD
Severe-WET,
FLD
Severe-FLO,
PCR
Severe-STP,
PFT
Daily
cover for
landfill
Poor-WET,SST
Poor-WET
Poor-SST,LCO
Poor-LST,PFT
Shallow
excavations
Severe-WET,
SST
Severe-WET,
PFT
Severe-FLD,
SST
Severe-STP,
PFT
Dwellings
Without With
basement basement
Severe-WET,
FLD
Severe-WET,
PFT
Severe-FLO
Severe-STP,
PFT
Severe-WET,
FLD
Severe-WET,
PFT
Severe-FLO
Severe-STP,
PFT
. Small
commercial
buildings
Severe-WET,
FLD
Severe-WET,
PFT
Severe-FLO
Severe-STP,
PFT
Local roads
and streets
Severe-l'lET,
FLD
Severe-WET,
PFT
Moderate-FLO
Severe-STP,
PFT
Picnic
areas
Severe-WET,
FLD
Severe-WET
Moderate-FLO
Severe-STP,
WET
Playgrounds
Severe-WET,
FLD
Severe-WET
Moderate-FLD
Severe-STP,
WET
Fairbanks High FaA-FaD;
Poor-FST
Unsuited FaA-FaB;Good FaA-FaB;Slight FaA;Moderate-
FaC;Moderate-PCR
FaA-FaC;Slight FaA-FaB;Slight FaA-FaB;Good FaA-FaB; Slight FaA-FaC; FaA-FaB;
Moderate-LBC
FaC;Moderate-
LBC,STP
FaD-FaF;
Severe-STP
FaA-Moderate-
LEe
FaB;Moderate-
LBC,STP
FaC-FaF;
Severe-STP
FaA-FaC;
Severe-FST
FaD-FaF;
Severe-FST·,
STP
FaA-FaB;Slight FaA;Slight
(FaA,FaB,FaC,
FaD,FaE,FaF)
Fairbanks, High
Moderately
deep
(FmB,FmC,FmD,
FmE,FmF)
Gilmore (GmB,
GmC, GmD, GmE ,
GmF)
Gilmore, very
shallow (GrB,
GrC,GrD,GrE,
GrF)
Moderate
Low
Goldstream High
(GtA,GtB,GtC)
Lemeta (Lp) High
Mine tailings Low
(Me)
Minto (MnA,
MnB,MnC)
High
Salchaket (Sc) Moderate
FaE-FaF;
Poor-FST,
STP
FmB-FmD;
Poor-FST
FmE-FmF;
Poor-FST,
STP
GmB-GmC;
Fair-LST
GmD;Fair
LST,STP
GmE-GmF;
Poor-STP
GrB-GrD;
Poor-LST
GrE-GrF;
Poor-LST,
STP
Sand;
Unsuited
Gravel;
Poor-FIN
Sand;
Unsuited
Gravel;
Poor-FIN
Sand;
Unsuited
Gravel;
Poor-FIN
Poor-WET, Unsuited
PFT
Poor-HUM, Unsuited
LBC
Fair-LST Good
Poor-FST Unsuited
Fair-FST Good
Salchaket,
Moderately
deep (Sm)
Salchaket,
shallow (Ss)
Moderate Fair-FST Good
Saulich (SuB,
SuC,SuD)
Tanana (Ta)
High
High
Limiting Features
SuB-SuC; Unsuited
Poor-PFT,
FST
SuD;Poor-
PFT STP
Poor-FST, Unsuited
PFT
FaC;Fair
FaD-FaF;
Poor-STP
FmB;Good
FmC;Fair-STP
FmD-FmF;
Poor-STP
Poor-THN,LST
,Poor-THN, LST
Poor-WET
Poor-WET
Poor-LST
MnA-MnB;Good
MnC;Fair-STP
Good
Fair-THN,SST
SuB-SuC;Poor-
PFT,WET
SuD;Poor-PFT,
STP
Good
BDR -Bedrock too shallow for the intended use
ERO -Soil is highly erodible
STP FaB;Moderate-
FaD-FaF; PCR,STP
Severe-STP FaC-FaF;
FmB-FmC;
Severe-Pes,
LST
FmD-FmF;
Sev~re-PCS,
STP
GmB-GmC;
Severe-Pes,
LST
GmD-GmF;
Severe-Pes,
STP
GrB-GrC;
severe-Pes,
LST
GrD-GrF;
Severe-Pes,
STP
Severe-WET,
PFT,FLD
Severe-WET,
PFT
Severe-LST
MnA-MnB;
Moderate-PIT
MnC;Moderate-
PIT,STP
Severe-FLO
Severe-FLO
Severe-WET,
PFT
Severe-WET,
PFT
Severe-STP
Severe-LST,
STP
Severe-LST,
STP
Severe-LST,
STP
Severe-FLO,
PFT
Severe-PFT,
HUM
Severe-PCR
MnA-MnB;
Severe-PIT
MnC;Severe-
PIT,STP
severe-FLO
Severe-FLD,
PCR
SuB;Severe-
WET,PFT
sue-SuD;
Severe-PFT
Severe-FLO,
PFT
FaD-Moderate-
STP
FaE-FaF;
Severe-STP
FmB-FmC;
Severe-LST
FmD-FmF;
Severe-LST,
STP
GmB-GmC;
Severe-LST
GmD-GmF;
Severe-LST,
STP
GrB-.GrC;
Severe-LST
GrD-GrF;
Severe-LST,
STP
Severe-WET,
FLD
Severe-WET,
PFT,HUM
Severe-LST,
PCR
Moderate-WET,
PIT
Severe-FLO
Severe-FLD,
PCR
Severe-WET,
PFT
Severe-WET,
FLD
FaC;Moderate-
STP
FaD-FaF;
Severe-STP
FmB;Slight
FmC;Moderate-
STP
FmD-FmF;
Severe-STP
GmB;Slight
GmC;Moderate,
STP
GmD-GmF;
Severe-STP
GrB;Slight
GrC;Moderate-
STP
GrD-GrF;
Severe-STP
Severe-WET,
FLD
severe-WET
Severe-PCR
MnA-MnB;
FaC;Fair-STP
FaD-FaF;Poor-
STP
FmB; Fair-THN
FmC;Fair-THN,
STP
FmD-FmF;Poor-
STP
GmB-GmC;Poor-
LST
GmD-GmF;Poor-
LST,STP
GrB-GrC;Poor-
LST
GrD-GrF;Poor-
LST,STP
Poor-WET
Poor-WET,
LCO
Poor-LST
MnA-MnB;Good
Moderate-WET, MnC;Fair-STP
PIT
MnC;Moderate-
WET,STP
Severe-FLO
Severe-FLO,
PCR
SuB-SuC;
Severe-WET
SuD;Severe-
WET,STP
severe-FLO
Good
Poor-SST,LCO
SuB-SuC;
Severe-WET,
PFT
SuD;Severe-
PFT STP
Moderate-PFT
FaC;Moderate-
STP
FaD-FaF;
Severe-STP
FmB-FmC;
Severe-LST,
FmD-FmF;
Severe-LST,
STP
GmB-GmC;
Severe-LST
GmD-GmF;
Severe-LST,
STP
GrB-GrC;
Severe-LST
GrD-GrF;
Severe-LST,
STP
Severe-WET,
PFT FLD
Severe-WET,
PFT
Severe-LST
MnA-MnB;
Moderate-WET
MnC;Moderate-
WET,STP
Severe-FLO
Severe-FLO,
SST
SuB-SuC;
Severe-WET,
PFT
SuD;Severe-
PFT,STP
Severe-WET,
PFT
LCO -Soil has poor compaction characteristics, is hard to pack
LST -Large stones limit suitability for the intended use
FIN -Excessive proportion of fine-grained material for the intended use
FLD Soil is subject to flooding
PCR -Permeability is too rapid for the intended use
PCS Permeability is too slow for the intended use
FST Soil is susceptible to frost action
HUM Peat soil
LBC -Soil has low strength or bearing strength
PFT Permafrost restricts use or is a hazard to structures
PIP Soil is subject to underground tunneling or piping
Severe-FST
FaD-FaE;
Severe-FST,
STP
FmB-FmC;
Severe-FST
FmD-FmF;
Severe-FST,
STP
GmB;Moderate-
FST
GmC;Moderate-
FST,STP
GmD-GmF;
Severe-STP
GrB;Slight
GrC;Moderate-
STP
GrD-GrF;
Severe-STP
Severe-WET,
PFT,FLD
Severe-WET,
PFT,HUM
Severe-LST
Severe-PIT,
FST
Severe-FLO
Severe-FLO
SuB-SuC;
Severe-PFT,
FST
SuD;Severe-
PFT,STP
Severe-FLO,
PFT
FmB;Slight
FmC;Moderate-
STP
FmD-FmF;
Severe-STP
GmB-GmC;
Severe-LST
GmD-GmF;
Severe-.LST,
STP
GrB-GrC;
Severe-LST
GrD-GrF;
Severe-LST,
STP
Severe-WET,
PFT,FLD
Severe-WET,
PFT,HUM
Severe-LST
Severe-PIT
Severe-FLO
Severe-FLO
SuB-SuC;
Severe-PFT,
FST
SuD;Severe-
PFT STP
Severe-FLO,
PFT
FmB;Moderate-
STP
FmC-FmF;
Severe-STP
FmB-FmC;
Severe-FST
FmD-FmF;
Severe-FST,
STP
GmB;Severe-LST GmB;Moderate-
GmC-GmF; FST
Severe-LST,
STP
GmC;Moderate-
FST,STP
GmD-GmF;
Severe-STP
GrB;Severe-LST GrB;Moderate-
GrC-GrF; LST
Severe-LST,
STP
Severe-WET,
PFT,FLD
Severe-WET,
PFT,HUM
Severe-LST
MnA-MnB;
Severe-PIT
MnC;
Severe-PIT,
STP
Severe-FLO
Severe-FLO
SuB;Severe-
PFT,FST
sue-suD;
Severe-PFT,
STP
Severe-FLO,
PFT
GrC;Moderate-
LST,STP
Severe-WET,
PFT FLD
Severe-LBC,
PFT,HUM
Moderate-LST
Severe-FST,
PIT
Moderate-FLO
Moderate-FLO
SuB-SuC;
Severe-PFT,
FST
SuD;Severe-
PFT STP
Severe-FST
FaC;Moderate-
STP
FaD-FaF;
Severe-STP
FmB;Slight
FmC;Moderate-
STP
FmD-FmF;
Severe-STP
GmB;Slight
GmC;Moderate-
STP
GmD-GmF;
Severe-STP
GrB;Slight
GrC;Moderate-
STP
GrD-GrF;
Severe-STP
Severe-WET
Severe-WET
Severe-LST
MnA-MnB;
Moderate-WET
MnC;Moderate-
WET,STP
Moderate-FLO
Moderate-FLO
SuB-SuC;
Severe-WET
SuD;Severe-
WET,STP
Moderate-FLO,
WET
PIT -Possible pitting beeause of thawing of buried ice masses
SST -Small stones limit suitability for the intended use
STP -Slopes are too steep for the intended use
THN Soil is thin over a substratum not suitable for the intended use
UNS -Soil is unstable when used in embankments
WET -Soil is too wet, or too poorly drained for the intended use
FaB;Moderate-
STP
FaC-FaF;
Severe-STP
FmB;Moderate-
STP
FmC-FmF;
Severe-STP
GmB;Moderate-
STP
GmC-GmF;
Severe-STP
GrB;Moderate-
STP
GrC-GrF;
Severe-STP
Severe-WET
Severe-WET
Severe-LST
MnA;Moderate-
WET
MnB;Moderate-
WET,STP
MnC;Severe-STP
Moderate-FLO
Moderate-FLO
SuB;Severe-
WET
sue-suD;
Severe-WET,
STP
Moderate-FLO,
WET
Features
affecting use for--
Pond Embankments, Corrosivity
reservoir dikes, and Untreated
area
PCR
PFT
PCR
STP ,PFT
PIP,STP
ERO,STP
ERO,STP
STP
PFT
PFT
PCR
PIT,ERO,
STP
PCR
PCR
PFT,STP
PFT
levees
PCR
LCO,PIP
PCR
THN,LST
LBC,PIP,
LCO
LBC,LST
LST
LST
LBC,PIP
UNS,LCO,
HUM
LST
LBC,PIP,
LCO
PCR
PCR
LBC,PIP
LBC,PIP
steel Concrete
High Moderate
High Low
Low Low
Moderate Moderate
Low Moderate
Low Moderate
Low Low
Low Low
High Moderate
Low Low
Low Moderate
Low Moderate
Low Low
High Low
High Low