Soil Survey of Dallas County, Texas Page: 42
vii, 153 p., 70 fold. p. of plates : ill., maps ; 29 cm.View a full description of this book.
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SOIL SURVEY
tion. The information, however, has limitations. For ex-
ample, estimates and other data generally apply only to
that part of the soil within a depth of 5 or 6 feet. Be-
cause of the map scale, small areas of different soils
may be included within the mapped areas of a specific
soil.
The information is not site specific and does not elimi-
nate the need for onsite investigation of the soils or for
testing and analysis by personnel experienced in the
design and construction of engineering works.
Government ordinances and regulations that restrict
certain land uses or impose specific design criteria were
not considered in preparing the information in this sec-
tion. Local ordinances and regulations need to be con-
sidered in planning, in site selection, and in design.
Soil properties, site features, and observed perform-
ance were considered in determining the ratings in this
section. During the fieldwork for this soil survey, determi-
nations were made about grain-size distribution, liquid
limit, plasticity index, soil reaction, depth to bedrock,
hardness of bedrock within 5 to 6 feet of the surface,
soil wetness, depth to a seasonal high water table,
slope, likelihood of flooding, natural soil structure aggre-
gation, and soil density. Data were collected about kinds
of clay minerals, mineralogy of the sand and silt frac-
tions, and the kind of adsorbed cations. Estimates were
made for erodibility, permeability, corrosivity, shrink-swell
potential, available water capacity, and other behavioral
characteristics affecting engineering uses.
This information can be used to (1) evaluate the po-
tential of areas for residential, commercial, industrial, and
recreation uses; (2) make preliminary estimates of con-
struction conditions; (3) evaluate alternative routes for
roads, streets, highways, pipelines, and underground
cables; (4) evaluate alternative sites for sanitary landfills,
septic tank absorption fields, and sewage lagoons; (5)
plan detailed onsite investigations of soils and geology;
(6) locate potential sources of gravel, sand, earthfill, and
topsoil; (7) plan drainage systems, irrigation systems,
ponds, terraces, and other structures for soil and water
conservation; and (8) predict performance of proposed
small structures and pavements by comparing the per-
formance of existing similar structures on the same or
similar soils.
The information in the tables, along with the soil maps,
the soil descriptions, and other data provided in this
survey can be used to make additional interpretations.
Some of the terms used in this soil survey have a
special meaning in soil science and are defined in the
Glossary.
Building site development
Table 8 shows the degree and kind of soil limitations
that affect shallow excavations, dwellings with and with-
out basements, small commercial buildings, and local
roads and streets. The limitations are considered slight if
soil properties and site features are generally favorable forthe indicated use and limitations are minor and easily
overcome; moderate if soil properties or site features are
not favorable for the indicated use and special planning,
design, or maintenance is needed to overcome or mini-
mize the limitations; and severe if soil properties or site
features are so unfavorable or so difficult to overcome
that special design, significant increases in construction
costs, and possibly increased maintenance are required.
Special feasibility studies may be required where the soil
limitations are severe.
Shallow excavations are trenches or holes dug to a
maximum depth of 5 or 6 feet for basements, graves,
utility lines, open ditches, and other purposes. The rat-
ings are based on soil properties, site features, and ob-
served performance of the soils. The ease of digging,
filling, and compacting is affected by the depth to bed-
rock, a cemented pan, or a very firm dense layer; stone
content; soil texture; and slope. The time of the year that
excavations can be made is affected by the depth to a
seasonal high water table and the susceptibility of the
soil to flooding. The resistance of the excavation walls or
banks to sloughing or caving is affected by soil texture
and the depth to the water table.
Dwellings and small commercial buildings are struc-
tures built on shallow foundations on undisturbed soil.
The load limit is the same as that for single-family dwell-
ings no higher than three stories. Ratings are made for
small commercial buildings without basements, for dwell-
ings with basements, and for dwellings without base-
ments. The ratings are based on soil properties, site
features, and observed performance of the soils. A high
water table, flooding, shrink-swell potential, and organic
layers can cause the movement of footings. A high water
table, depth to bedrock or to a cemented pan, large
stones, and flooding affect the ease of excavation and
construction. Landscaping and grading that require cuts
and fills of more than 5 to 6 feet are not considered.
Local roads and streets have an all-weather surface
and carry automobile and light truck traffic all year. They
have a subgrade of cut or fill soil material, a base of
gravel, crushed rock, or stabilized soil material, and a
flexible or rigid surface. Cuts and fills are generally limit-
ed to less than 6 feet. The ratings are based on soil
properties, site features, and observed performance of
the soils. Depth to bedrock or to a cemented pan, a high
water table, flooding, large stones, and slope affect the
ease of excavating and grading. Soil strength (as in-
ferred from the engineering classification of the soil),
shrink-swell potential, and depth to a high water table
affect the traffic supporting capacity.
Sanitary facilities
Table 9 shows the degree and the kind of soil limita-
tions that affect septic tank absorption fields, sewage
lagoons, and sanitary landfills. The limitations are consid-
ered slight if soil properties and site features are gener-42
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General Soil Map, Dallas County, Texas (Map)
Map displays soil types along with creeks, towns, schools, churches, power transmission lines, oil and gas pipelines, roads, and railroads. Includes legend and symbols. Scale 1:253,400
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Coffee, Daniel R. Soil Survey of Dallas County, Texas, book, 1980; Washington D.C.. (https://texashistory.unt.edu/ark:/67531/metapth130211/m1/52/: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting UNT Libraries Government Documents Department.