HomeMy WebLinkAboutSoil AnalysisSo¡l AnnLYsts
USDA
-
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Gustom Soil Resource
Report for
Rifle Arean Golorado,
Parts of Garfield and
Mesa Counties
Davis Residence OWTS
NRCS
Natural
Resources
Conservation
Service
May 12,202'l
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officíals, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local govemments may impose
special restrictions on land use or land treatment. Soil surveys identiff soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
casês. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://ofüces.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www nrcs. usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs1 42p2_053951 ).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstiable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
lnformation about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for ofücial soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, maritalstatus, familialstatus, parentalstatus, religion,
sexual orientiation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
altemative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDAs TARGET Genter at(202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Ofüce of
Civil Rights, 1400 lndependence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202)720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Gontents
Preface.......
SoilMap.....
SoilMap......
Legend........
Map Unit Legend
Map Unit Descriptions
Rifle Area, Colorado, Parts of Garfield and Mesa Counties......
40-Kim loam, 3 to 6 percent slopes.
73-Water...
Soil lnformation for All Uses............
SoilReports...
Soil Physical Properties...
Physical Soil Properties (Davis Residence OWTS).
Engineering Properties (Davis Residence OWTS)..
2
5
.o
.7I
9
11
11
11
12
12
12
12
16
4
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
5
"8NulzqH21070 36'14 W/ßm43æ?r4M 4ep1l()tl107" 36,14w H>>=ÈÈEÈËðdaäBËNdËÈdüc)cU'o3ØØ 9,9.. n<EaorocðonoEo=(')Èäd6äH+qNqzqNz43m10-lo 36'S Wi(m€mæm4W6043ffi4M4:m4M1070 368W
Custom Soil Resource ReportMAP LEGENDMAP INFORMATIONThe soil surveys thd comprise yourAol were mapped at1:24"O0O.Please rely on the bar scale on each map sheet for mapmeasurements.Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL:Coordinate System: Web Mercator (EPSG:3857)Maps from the Web Soil Survey are based on the Web Mercatorprojec'tion, wh¡ch preserues direction and shape but distortsdistance and area. A projêc-tion that preserves area, such as theAlbers equal-area conic projection, should be used if moreaccurate calculations of distance or area are required.This product is generated from the USDA-NRCS certified data asof the vercion date(s) listed belowSoil Survey Area: Rif,e Area, Colorado, Parts of Garfield andMesa CountiesSurveyArea Data: Version 13, Jun 5,2020Soil map units are labeled (as space allows) for map scales1:50,000 or larger.A]Ea of lnterest (AOl)E Area of lnterest (AOl)So¡lst] Soil Map Unit Polygonst+ Soil Map Unit LinesI Soil Map Unit PointsSpeciel Point Fêatur€s(Ð Blor/outHl Bonow PitH Clay Spotö Closed Depression¡ç GravelPit¿ Gravelty Spot(} LandfillÅ" Lava FloiY& Marsh orswamp# Mine or Quarryü Miscêllaneous Waterð PerennialWater\ú{ Rock Outcrop+ Saline Spotl": Sandyspot#" SeverelyErodedSpot# Sinkholeþ Slide or Slipø SodicspotË Spo¡l Aread Stonyspotffi VeryStonyspotS Wetspot& Other.- Special Line FeaürlesWator FeaturesSt¡sams and CanalsTransportatlonffi Ra¡lsH lnterstat€ Highways# UsRoutes..:: ri, Major RoadsLocal RoadsBackgroundt Aerial PhotographyDate(s)12,201aerial imageswere photographed: Dec 31, 200Hct7The orthophoto or other base map on which the soil lines werecompiled and digitized probably differs from the bac(ground7Waming: Soil Map may not be valid at this scale.Enlargement of maps beyond the scale of mapp¡ng can causemisunderstanding of the detail of mapping and accuracy of soilline placement. The maps do not show the small areas ofcontrasting soils that could have been shown at a more detailedscale.
Gustom Soil Resource ReportMAP LEGENDMAP INFORMATIONimagery displayed on these maps. As a result, some minorofunit boundariesbe evident.8
Custom Soil Resource Report
Map Unit Legend
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the Survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management' These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components' They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. lf included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identifo allthe soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. lf intensive use of small areas is planned, however,
I
lllap Unlt Symbol Map Unlt Name Aclcs ln AOI Psrcent ofA(ll
40 Kim loam, 3 to 6 percent slopes 1.6 99.9%
73 Water 0.0 0.1o/o
Totals for Area of lntsrcst 1.6 100.0%
Custom Soil Resource Report
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soi/ senbs. Except for
differences in texture of the surface layeç all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layeç slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into so/ phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An assoclafibn is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area arê not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
10
Custom Soil Resource Report
Rifle Area, Golorado, Parts of Garfield and Mesa Gounties
40-Kim loam, 3 to 6 percent sloPes
Map Unit Setting
National map unit symbol: iny7
Elevation: 5,000 to 6,000 feet
Farmland classifrcation' Prime farmland if irrigated
Map Unit Composition
Km and similar soils:85 percent
Estimates are based on obseruations, descríptions, and triansecfs of the mapunit.
Description of Kim
Setting
Landfotm: Benches, alluvial fans
Down-slope shape: Convex, linear
Across-s/ope shaPe: Convex, linear
Parent material: Alluvium derived from sandstone and shale
Typicalprofile
Hl - 0 to 17 inches: loam
H2 - 17 to 60 inches.' loam
Properties and qualities
S/ope;3to6percent
Depth to restrictive feature: More than 80 inches
Drainage c/ass: Well drained
Runoffclass: Low
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high
(0.60 to 6.00 in/hr)
Depth to watertable: More than 80 inches
Frequency of flooding; None
Frequency of Pondng; None
Calcium carbonate, maximum content: 15 percent
Available water capacity: High (about 9.6 inches)
lnterpretive groups
Land capability classification (hrigated): 3e
Land capability classification (nonirrigated): 3c
Hydrologic So/ Gtoup: A
Ecologicalsde; R048AY298CO - Rolling Loam
Hydricsoflrafing: No
73-Water
Map Unit Composition
Water:100 percent
Estimates are based on obseruations, descriptions, and transects of the mapunit.
11
Soil lnformation for All Uses
Soil Reports
The Soil Reports section includes various formatted tabular and narrative reports
(tables) containing data for each selected soil map unit and each component of
each unit. No aggregation of data has occurred as is done in reports in the Soil
Properties and Qualities and Suitabilities and Limitations sections.
The reports contain soil interpretive information as well as basic soil properties and
qualities. A description of each report (table) is included.
Soil Physical Properties
This folder contains a collection of tabular reports that present soil physical
properties. The reports (tables) include all selected map units and components for
each map unit. Soil physical properties are measured or inferred from direct
observations in the field or laboratory. Examples of soil physical properties include
percent clay, organic matter, saturated hydraulic conductivity, available water
capacity, and bulk density.
Physical Soil Properties (Davis Residence OWTS)
This table shows estimates of some physical charaoteristics and features that affect
soil behavior. These estimates are given for the layers of each soil in the survey
area. The estimates are based on field observations and on test data for these and
similar soils.
Depth to the upper and lower boundaries of each layer is indicated'
Particle size is the effective diameter of a soil particle as measured by
sedimentation, sieving, or micrometric methods. Particle sizes are expressed as
classes with specific effective diameter class limits. The broad classes are sand,
silt, and clay, ranging from the larger to the smaller.
Sand as a soil separate consists of mineral soil particles that are 0.05 millimeter to 2
millimeters in diameter. ln this table, the estimated sand content of each soil layer is
given as a percentage, by weight, of the soil material that is less than 2 millimeters
in diameter.
S/f as a soil separate consists of mineral soil particles that are 0'002 to 0.05
millimeter in diameter. ln this table, the estimated silt content of each soil layer is
12
Custom Soil Resource Report
given as a percentage, by weight, of the soil material that is less than 2 millimeters
in diameter.
Ctay as a soil separate consists of mineral soil particles that are less than 0.002
millimeter in diameter. ln this table, the estimated clay content of each soil layer is
given as a percentage, by weight, of the soil material that is less than 2 millimeters
in diameter.
The content of sand, silt, and clay affects the physical behavior of a soil. Particle
size is important for engineering and agronomic interpretations, for determination of
soil hydrologic qualities, and for soil classification.
The amount and kind of clay affect the fertility and physical condition of the soil and
the ability of the soil to adsorb cations and to retain moisture. They influence shrink-
swell potential, saturated hydraulic conductivity (Ksat), plasticity, the ease of soil
dispersion, and other soil properties. The amount and kind of clay in a soil also
affect tillage and earthmoving operations.
Moist bulk densify is the weight of soil (ovendry) per unit volume. Volume is
measured when the soil is at field moisture capacity, that is, the moisture content at
113- or 1/1o-bar (33kPa or 1OkPa) moisture tension. Weight is determined after the
soil is dried at 105 degrees C. ln the table, the estimated moist bulk density of each
soil horizon is expressed in grams per cubic centimeter of soil material that is less
than 2 millimeters in diameter. Bulk density data are used to compute linear
extensibility, shrink-swell potential, available water capacity, total pore space, and
other soil properties. The moist bulk density of a soil indicates the pore space
available for water and roots. Depending on soil texture, a bulk density of more than
1.4 can restrict water storage and root penetration. Moist bulk density is influenced
by texture, kind of clay, content of organic matter, and soil structure.
Saturated hydrautic conductivity (Ksaf) refers to the ease with which pores in a
saturated soil transmit water. The estimates in the table are expressed in terms of
micrometers per second. They are based on soil characteristics observed in the
field, particularly structure, porosity, and texture. Saturated hydraulic conductivity
(Ksat) is considered in the design of soil drainage systems and septic tank
absorption fields.
Avaitable water capacity refers to the quantity of water that the soil is capable of
storing for use by plants. The capacity for water storage is given in inches of water
per inch of soil for each soil layer. The capacity varies, depending on soil properties
that affect retention of water. The most important properties are the content of
organic matter, soiltexture, bulk density, and soil structure. Available water capacity
is an important factor in the choice of plants or crops to be grown and in the design
and management of irrigation systems. Available water capacity is not an estimate
of the quantity of water actually available to plants at any given time.
Linear extensróltdy refers to the change in length of an unconfined clod as moisture
content is decreased from a moist to a dry state. lt is an expression of the volume
change between the water content of the clod at 113- or 1110-bar tension (33kPa or
1QkPa tension) and oven dryness. The volume change is reported in the table as
percent change for the whole soil. The amount and type of clay minerals in the soil
infl uence volume change.
Linear extensibility is used to determine the shrink-swell potential of soils. The
shrink-swell potential is low if the soil has a linear extensibility of less than 3
percent; moderate if 3 to 6 percent; high if 6 to 9 percent; and very high if more than
9 percent. lf the linear extensibility is more than 3, shrinking and swelling can cause
13
Custom Soil Resource Report
damage to buildings, roads, and other structures and to plant roots. Special design
commonly is needed.
Organic matteris the plant and animal residue in the soil at various stages of
decomposition. ln this table, the estimated content of organic matter is expressed
as a percentage, by weight, of the soil material that is less than 2 millimeters in
diameter. The content of organic matter in a soil can be maintained by returning
crop residue to the soil.
Organic matter has a positive effect on available water capacity, water infiltration,
soil organism activity, and tilth. lt is a source of nitrogen and other nutrients for
crops and soil organisms.
Erosion factors are shown in the table as the K factor (Kw and Kf) and the T factor.
Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by
water. Factor K is one of six factors used in the Universal Soil Loss Equation
(USLE) and the Revised Universal Soil Loss Equation (RUSLE) to predict the
average annual rate of soil loss by sheet and rill erosion in tons per acre per year.
The estimates are based primarily on percentage of silt, sand, and organic matter
and on soil structure and Ksat. Values of K range from 0.02 to 0.69. Other factors
being equal, the higher the value, the more susceptible the soil is to sheet and rill
erosion by water.
Erosion factor Kw indicates the erodibility of the whole soil, The estimates are
modified by the presence of rock fragments.
Erosion factor KÍindicates the erodibility of the fine-earth fraction, or the material
less than 2 millimeters in size.
Ercsion factor T is an estimate of the maximum average annual rate of soil erosion
by wind and/or water that can occur without affecting crop productivity over a
sustained period. The rate is in tons per acre per year.
Wnd erodibility groups are made up of soils that have similar properties affecting
their susceptibility to wind erosion in cultivated areas. The soils assigned to group I
are the most susceptible to wind erosion, and those assigned to group 8 are the
least susceptible. The groups are described in the "National Soil Survey Handbook."
Wind erodibility index is a numerical value indicating the susceptibility of soil to wind
erosion, or the tons per acre per year that can be expected to be lost to wind
erosion. There is a close conelation between wind erosion and the texture of the
surface layer, the size and durability of surface clods, rock fragments, organic
matter, and a calcareous reaction. Soil moisture and frozen soil layers also
influence wind erosion.
Reference:
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-Vl. (http://soils.usda.gov)
14
Custom Soil Resource ReportThree values are provided to identifo the expected Low (L), Representative Value (R), and High (H).Physlcal Soil Properties..Rlfle Aloa, Golorado, Parte of Garfield and llesa CountlesWnderodlbilitylndex86Ullnderodlbllitygroup4tEtosionfac'torsT5t('.24.32Kw.24.32OrganlcmatterPct0.s,0.8-1.00.s 0.&1.0LlnearextensibllityPd0.0- 1.5- 2.90.G. 1.5- 2.9AvallablewatercapacityIn/ln0.14-0.1ôO.170.14-0.16-0.17Saturaûedhydraullcconducüvlfmicro m/sec4.23-23.2842.344.23-23.2U2.34tloistbulkdens¡tyg/cc1.25-1.33-1.401.25-1.33-1.40ClãyPd,15-20-2515-2ù25siltPct-3&-38-SandPd42-42-Depthln0-17l7-60Map symboland Boil namo4H(m loam,3 to 6 percentslopesKim73--WaterWater15
Custom Soil Resource Report
Engineering Properties (Davis Residence OWTS)
This table gives the engineering classifications and the range of engineering
properties for the layers of each soil in the survey area.
Hydrologic soil group is a group of soils having similar runoff potential under similar
storm and cover conditions. The criteria for determining Hydrologic soil group is
found in the National Engineering Handbook, Chapter 7 issued May 2007(http://
directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=17757.wba).
Listing HSGs by soil map unit component and not by soil series is a new concept for
the engineers. Past engineering references contained lists of HSGs by soil series.
Soil series are continually being defined and redefined, and the list of soil series
names changes so frequently as to make the task of maintaining a single national
list virtually impossible. Therefore, the criteria is now used to calculate the HSG
using the component soil properties and no such national series lists will be
maintained. All such references are obsolete and their use should be discontinued.
Soil properties that influence runoff potential are those that influence the minimum
rate of infiltration for a bare soil after prolonged wetting and when not frozen. These
properties are depth to a seasonal high water table, saturated hydraulic conductivity
after prolonged wetting, and depth to a layer with a very slow water transmission
rate. Changes in soil properties caused by land management or climate changes
also cause the hydrologic soil group to change. The influence of ground cover is
treated independently. There are four hydrologic soil groups, A, B, C, and D, and
three dual groups, A'/D, B/D, and C/D. ln the dualgroups, the first letter is for
drained areas and the second letter is for undrained areas.
The four hydrologic soil groups are described in the following paragraphs:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly
wet. These consist mainly of deep, well drained to excessively drained sands or
gravelly sands. These soils have a high rate of water transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well drained
soils that have moderately fine texture to moderately coarse texture. These soils
have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of water
transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay layer at
or near the surface, and soils that are shallow over nearly impervious material.
These soils have a very dow rate of water transmission.
Depth lo the upper and lower boundaries of each layer is indicated.
Terture is given in the standard terms used by the U.S. Department of Agriculture.
These termg are defined according to percentages of sand, silt, and clay in the
fraction of the soil that is less than 2 millimeters in diameter. "Loam," for example, is
soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand.
lf the content of particles coarser than sand is 15 percent or more, an appropriate
modifier is added, for example, 'gravelly."
16
Custom Soil Resource Report
Ctassification of the soils is determined according to the Unified soil classification
system (ASTM, 2005) and the system adopted by the American Association of
State Highway and Transportation Officials (AASHTO, 2OO4).
The Unifted system classifies soils according to properties that affect their use as
construction material. Soils are classified according to particle-size distribution of
the fraction less than 3 inches in diameter and according to plaSticity index, liquid
limit, and organic matter content. Sandy and gravelly soils are identified as GW GP,
GM, GC, SW, SP, SM, and SC; silty and clayey soils as ML, CL, OL, MH, CH, and
OH; and highly organic soils as PT. Soils exhibiting engineering properties of two
groups can have a dual classification, for example, CL-ML.
The MSHTO system classifies soils according to those properties that affect
roadway construction and maintenance. ln this system, the fraction of a mineral soil
that is less than 3 inches in diameter is classified in one of seven groups from A-1
through A-7 on the basis of particle-size distribution, liquid limit, and plasticity index.
Soils in group A-1 are coarse grained and low in content of fines (silt and clay). At
the other extreme, soils in group A-7 are fine grained. Highly organic soils are
classified in group A-8 on the basis of visual inspection.
lf laboratory data are available, the A-1, A-2, and A-7 groups are further classified
as A-1-a, A-1-b, A-24, A-2-5, A-2-6, A-2-7, A-7-5, or A-7-6. As an additional
refinement, the suitabílity of a soil as subgrade material can be indicated by a group
index number. Group index numbers range from 0 for the best subgrade material to
20 or higher for the poorest.
Percentage of rock fragmenfs larger than 10 inches in diameter and 3 to 1 0 inches
in diameter are indicated as a percentage of the total soil on a dry-weight basis. The
percentages are estimates determined mainly by converting volume percentage in
the field to weight percentage. Three values are provided to identifo the expected
Low (L), Representative Value (R), and High (H).
Percentage (of soil particles) passing designated sieves is the percentage of the soil
fraction less than 3 inches ín diameter based on an ovendry weight. The sieves,
numbers 4, 10, 40, and 200 (USA Standard Series), have openings of 4.76, 2'00,
0.420, and 0.074 millimeters, respectively. Estimates are based on laboratory tests
of soils sampled in the survey area and in nearby areas and on estimates made in
the field. Three values are provided to identiff the expected Low (L), Representative
Value (R), and High (H).
Liquid limit and plasticity index (Atterberg limits) indicate the plasticity
characteristics of a soil. The estimates are based on test data from the survey area
or from nearby areas and on field examination. Three values are provided to identify
the expected Low (L), Representative Value (R), and High (H)'
References:
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-OO'
17
Custom Soil Resource ReportAbsence of an entry indicates that the data were not estimated. The asterisk'*' denotes the representative texture; otherpossible textures follow the dash. The criteria fur determining the hydrologic soil group for individual soil components isfound in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=17757.wba). Three values are provided to identify the expected Low (L),Representative Value (R), and High (H).Engin66r¡ng Propertles-Rlflo Arêa, Colorado, Parb of Garf¡ôld and Itesa CountleePlasticlty lndexL-R-H5-8 -105-8 -10LlquldllmltL-R-H25-28-3025-28-30Percentage passlng sieve number-200L-R-H606&7560-68-7540L-R-H85-90-9585-90-95l0L-R-H100-100-100100-100-1004L-R-H100-100-100100-100-100Pc't Fragments3-t0inchesL-R-HGG.O0-G 0>,10lnchesL.R-H0-0-00-0-0ClasslflcatlonAASHTOA-4A-4UnlfiedCL, CL-MLcL, cL-MLUSDAtextureLoamLoamDepthIn0-17'1760HydrologlcgroupAPct. ofmapunlt85f$ap unit symbol andso¡l name4S-Kim loam, 3 to 6percent slopesKim18
1.0 Detailed Soil lnvestigation
A detailed soil investigation to determine the depth to the limiting layer and properly classify the soil
type was conducted using Colorado Professionals in Onsite Wastewater (CPOW) Soil and Site
Evaluation methodology. Visual evaluation of two soil profile test pits were conducted in the field and
textural evaluation of samples collected from each test pit were conducted at SGM's Office. The test
pits were excavated adjacent to the proposed location for the STA. Visual evaluation of both test pits
was conducted under adequate light conditions, with the soil being in an unfrozen state.
Ll Visual Evaluation
The Client's Contractor excavated two soil profile test pits, TP-1 and TP-2, adjacent to where the
STA will be located prior to SGM being on site. Both test pits were excavated to an approximate
depth of I feet, with no groundwater nor bedrock being encountered, nor were there visible signs
of water when evaluated by SGM.
Both test pits exhibited topsoil to a depth of 16 to 18 inches, then two distinct visual horizons from
the bottom of the topsoil zone to the bottom of each pit. The first horizon, between the depths of
16/18 inches to 43 inches consisted of soils that appear to have a texture of silty clay. The second
horizon, between the depths of 43 inches to 96 inches contained fine to coarse gravels with a
mixture of the silty clay soils, the gravels making up between 35 to 65 percent of the soils within
the second horizon.
Visual observations showed the third horizon would be a limiting layerand the soils would classify
as a Type "R". As such, soil samples from each pit were collected for the second horizon at a
depth of 36" and taken to SGM's Office for textural analysis. Soil observation logs and photos
can be found in the Appendix.
All measurements are from ground surface.
1.2 Tactile Evaluation
SGM conducted a SoilTexture by Feel test on the soil samples collected from each test pit per
CPOW's methodology.
Gravels were present in both samples, but at a percentage less than 35%. Therefore, Table l0-
1, Section 43.10 of the Garfield County OWTS regulations was used to determine the long term
application rate (LTAR) for the soil type classification.
The soil texture by feel method using the CPOW Soil Texture Flow Chartwas conducted on each
sample. Results are shown in the following table.
SAMPLE
Depth from
Ground
Surface (ft)
Does Soil
Form a Ball
(yes/no)
Does Soil
Form a
Ribbon
(ves/no)
*Type of Ribbon
Formed (Weak,
Moderate,
Stronol
How Does the Soil Feel
(Gritty/Smooth/Neither)
TP-1 3.0 Yes Yes Stronq Smooth
fP-2 3.0 Yes Yes Stronq Smooth
"Weak < 1 inch; Moderate 1-2 inches; Strong > 2 inches.
From the results shown in the above Table, the limiting layerwould have a USDA soil classification
of Silty Clay, soil type 4 or 44.
To determine the proper soil $pe, 4 or 4A, the USDA soil structure type and grade were used
The following Table shows the soil's USDA structure type and grade determined foreach sample
SAMPLE
USDA Soil
Structure
Tvoe
USDA Soll
Structure
Grade
TP-1 Blockv Moderate
TP-2 Blocky Moderate
According to Table 10-1, section 43.10 of the Garfield County OWTS regulations, both soiltypes,
4 and 44, can have a blocky USDA soilstructure type, but only soiltype 4 can have a moderate
USDA soil structure grade. As such, the limiting layer soil type is classified as soil type 4, having
a LTAR of 0.20 for treatment level 1 (TL1).
SGM's worksheets for the Soil Observation Logs, Soil Texture by Feel and STA LTAR by Soil
Texture, Soil Structure and Treatment Levels can be found in the Appendix.
2
Appendix
TP-1 Trench Photo
TP-l Trench Photo
TP-2 Trench Photo
TP-2Trench Photo
SGM Soil Observation Logs
Water Volume Displacement Method
SGM Soil Texture by Feel
3
TP-1
TP-1
TP.2
TP.2
OSGM Soll ProfflaTetPltGnptrlctof t{umbcn fZ t
lg, ^. tya
wlTNTilFET ¿
2313D
0 1 76
tr
Ë
=
Ët¡¡ô
D
¡tqrú¡üflc.
4
t
I
I
2
3
5
6
7
)
,l I '/1 (7 Þ L)t
I
I
I
\,t t
v
\
\
I IttIl.r I
.¡
l
n /l/
7 I '/(a€4 t(t"ç J Io
\
I
t
I
I
I
/
II
II
rllnIII.I
II
IDoftñ lhlISoil Observation Logssd[47:ao,4Tenu¡tRod(Metfbt*motdêRedq Strucfr¡re SltucÞte Coßig¡eîceGfâde. fÈ,I -¿ /oWeatlpr conditionsÆime ofElenatftrn:Observ¡üonPv Qî L^lBedrockLoese Orgnnlc MatlelSoll Parent i¡taterbl(sl: Tlllall thatToeFoottegâl D$cdpt¡on/GPS:cllem/ Addrese:rDste:f&ajolÛilh¡c'{hcrllthúüúncrf, nLaÍdl¡Üt'rlrrptatl¡Læ¡?Fri¡btfLrn&llilltFfinnddF r¡bbFrnSffiVFlrtrldcó1,ÉÉ.Fl¡UrFlmEA'trrl.tF tlLagsaFft¡bþFfrhãütllratf ÉtrrFriaþ|"fumæ¿írrÌFrilni¡ldtoo6tEd'ttrcþnimR1,.,Mode'lþStrrl|tæ.wltüüor¡trÞsr|þclêftorFttÊSlton!tæþa¡atdcr¡taCrøl3l¡erhüÉûfrþrxltsglthtr.lrrtrnl|o.rrât|dcld.grrlûdrñtrtlsh6úårt¡útÈbûrhthl¡6t*t*aÞ6rÈ,lt,lLût'tffic,$a¡6¿¡lCofioen?don3DepþdonsClåycdConcmtr¡üonsOedctloôs€lÊTpdc.oncentratþËDedetion36leye¿coneef¡trdongDepleüo¡rsGWConc¿r¡uadonsDepþüonsGleyÊd@ræntrðtiontDeplEtiontGleyedG x.¡u'ELscs?Ll*r¿Ç,h5"; Ir,ç,11rel-0-1 L'+js-nb
I gSGM
SOIL PROFITE TESÍ PIT TOG
tA SEPARAIE tOG çËAtt Bl GoMPIEIED FOR EACI{ sot PRoFlll lEsf Pffl
Test Pit Number: 7 P- /Dåte of Losglrc,5 J-il,-zj-
PropertyAddress: -
ncdorlmorPhk
flú¡tlô
Prr.ntt fYlt{}
Soll TYPC
(ÎlUc loor'F
SolbtnTrbhril
Soll Stn¡ctt¡tt
6nds
USDASoII
Structurc -
ïYpG
USDASo¡lTÊrturc
Ρn¡c of Dcpth ofSoil
Hort¿on, RGbüut to Groünd
S¡¡rf¡cc
<
/z>3o t1) êt k
Q- tR l- -l<,,lv\n)¿¡** ¿I.- ^,tU - a a1Ë *)) ,'^,'1,-^., I/5 r c- ø/{ ¿,C$.¡41¡,a-Ql^J
\
Notêsi
ls there e llmklng layer as dcflncd ln Regulrtion {Þ1??trNo
lfyes,desl8ndocumentmustexplalnhowthcllmlüngcondltlonb¡dd¡cssed.
ls Dawson Arko¡e tDA! or Cemented Sand (CSl prcscnt? E Ye¡ E No
lf yes, Plcase answer thc followlng:
ls matcrlal fractured and/ortolnted? El Y€s El No
frvhet ¡5 the ccment¡tþn clas¡?
l¡the D¡wson Arkose orCemcnted llmltlq lrycrpcr¡cclon 8.78.2 sf G17? El ve¡ El tto
s{o
O
OSGM Soll Proffh T¡¡t Plt Gnphþ fol flumbcr:
WDNTNtGEf
Z?4
læ
&n "¡l.1'..I 76501
€rurta¡txt¡G.
1
7
3
o 4tr¡¡¡t¡.
|E
Eu¡êr 5
6
7
8
-Tlttttlltlltt
Ð(-T | Yrt,Ås-
ll-ll
tttt -T I ts,II'L-T-rl I t I-lttttL
LTl tttt_ltt L II-t I tt LTt tttl_L a /c,&-T I I^f'fl''ttt ttt t
-TltttL-1 lltll-llllll
I 4t"lttttl a1-tII/,ltt_ttt
tr)5t{-l I I {'',tlt"-t-t I I lr ?
2 t ¡lI I I Ltl-Ttttlr I I I U40-Tl I I I ITl llll
lll--rlllll
tttt
IL
II
o 9
oISoil Observation Loggsoe¡'û llnl. Ïe¡tutoRock Meffiitqttl€R€d¡prStn¡qture sùutü¡re ConsÉtence-{/,e/uarro¡t h ¡cødror dû ¡l ¡¡¡iath üúl¡l.r1 ûlc ürd ||l|!.¿L2-5%Elemtion:ofWeatherMâpaáObseruationt?CCê7(a)/FnCllenl Addres¡:Drts:Descrþtton/GP3:þSalEedrocltLoêss Organlc MattcrnI5oll Èrent lrlaterlrr{s) :¡ll thatLæ¡.çåi¡r -.F¡im€rÎr€nelf F¡nñIEtftt'ær€Rl|¡.,FrþbEgñ:",E{rlnrdy¡irmLoGCRl¡blcF¡fmÉrFEmclt F'fnflffi)Iroac?rlibþRfmEr¡r¡úelv Fhni¡aldlôüaF tÐbbFm¡æ€flrllyHñHddErtrçrllett fhrhirddtoo¡aF i¡U¿fkûll¡@wcq3-*-¡tfuntc ,)lû'úE--wts*nWffi¡¡oûêWó¡(t/tdúrÞsffi)tôc¡lliUl.tf,lô.tcñtè5ùútLao*wt¡*ùlodere6ûm3LoôEèrflãt!¡io.Lr¡taStroa¡tæo!9t#.6r¡a(Gms¡'Dlñr'Dbt*r/'ñúGôr¡¡batttt@Dtlmrdc9r!Þ6r*rb{lllr¡¡/.lrúç'lþ.ù,flbñ¡dcIrda6frfiIt¡rLffiñl¡tøod,trt*¡h¡h6tJr!frqkfttrbúrtìtfrr¡cSelllÉrd,tfra¡úcCn rd¡t?tat@raûÞt¡oatttltfltkffrlbG¡*!l{IrtËConcÊntr¿tionsDeplerions6leyedConcentr¡tfonsDeplcdonsGI¡rlsdconenrðuolr9DepletiomCf€VedConce¡trat¡onsDegle$ons6l€ysdConc¿ntr¡üonsDcdcüoniGlqedConcêntrdonsDcdetlons6lsyedS, t+t etnf 41;',e f u'C-q';'? l lttíl 4f,7l'; ¡(.ro9; l{/r{ t-1b72.-slt-72to¡rar¡t¡¡
o OSGM
SOIL PROTITE TEST PIT TOG
TASEPAßAIE tOG SHAtt BE COMP1ETEDFOR CACH SOF PnOfllEÎEsrPfrl
TË¡t Plt t¡umUcr: 7 f -'¡-Datèof [oEBtrw;CilU-
lrn¡o ofDcpth of$oll
Horlton, Rd¡tlv¡ to G¡tu¡td
Surfrcc
USDASolllcnurc
USDASoII
3tnrcturr -
TYpc
Soü$rucn¡rg.
Gndc
Solllþc
lTrUc 10r'f
Soll¡ ln T¡bl¡
1Ð
ndodtrorpltlc
fcrn¡c¡
Pr!r.nt? (T/x)
¡; ¡')l.^ <o,l IJ
IC,¡+,,Lrn,,R Io. !< ,t Y?\ )or-),c t2-t A)
" ¡ ,,];.ç,f '-f ¿ {Ê,-r,t,I T,+I ^..,\l
¡7-
Not¡sl
ls thcrc ¡ llmhlng laycr as d¡f ncd ln Regulrtion &17?/ro o no
$ yes, deslgn doGument must orphln how the llmldng condltlon lc ¡ddfG¡¡ed.
ls Dawson Arkoee tDA) ot Cemented Sand (CSl p¡csent? tr Ves ffi
tf Ves, plcasc answcr tlre followlng:
ls m¡tcrlal frastured and/orjolnted? E Yes E No
Whet lsthc ccmcntftlon d¡ss?
l¡ thc D¡wson Arko6! or Cemmted Sand þ llmltlu lay:r pcr sccdon 8,?8.2 of ().17? Et Y¡¡ Et No
I
Io
ÐÐgSGM
aÁl et
,P
r
i
:q.Ått li*4
i
t)A
{d
-1
l--i --
!
I
i' t- .----1'
:
l1
l'. ¡ - -,.f -*
l
ir
l
- ,1.. *,,
' _.._'_;-*--
---
.
--
i
1
t()O 11 I
;{-
'Jç.
4))D ,/, )
1
-. t...--*
i3.(Ðt rtl t)a I
I
¡
I
,
ÊortU t It^ L)/7 {'7 l-ê.Jè
,Ò h.-ì il-- i
C
I
I
I II
i
ii
,.ir'*
2021-319.001 Samples 1 and 2
Soil Texture by Feel Does the soil remain in a ball when squeezed?
Place soil in palm of hand, Add water drop-wise
and knead the soil into a smooth and plastic
consistenc¡ like moist
putty.
Place ball of soil between thumb and forefinger,
gently pushing the soil between with the thumb,
squeezing it upward into a ribbon. Form a ribbon
of uniform thickness and width. Allow
ribbon to emerge and extend
over the forefinger,
breakingfrom
its ourn
weighl
B¿r€d on U50Á l{fi(5 Guidr t0 tenüre by fsel - 5. .,, nìkn, 1979, mdtñ€d.
Ihh yôr¡åt¡on (eôlêd by D Hånlim, M Brown, W 8r0wn, ß t¿ñ.
Add water ry soil
Yes
ls the soil too dry?
No Yes
the soiltoo wet?
No
kind of ribbon does it form?
Yes No -JI no¿a
3
2
€È
c
ts
0
Does ¡oil feel very gritty? Yes
No
Forms a weak
ribbon less
than l"before
breaking
þm
5oüSpelø?Â
5mf tom
Forms a1-2"
ribbon before
breaking
Does soilfeel very smooth? Yes
No
Nelther gritty nor smooth? Yes i,m
before
2" ol
a
the soil form a ribbon?
3
L
rìT
.-'.1
't'r't l
I
1.,.¡,
'l'
I I I
'|,t-1-t'
€:2 i'
L*.*"o."
l't,
4.
'r''f ' I '
'!i
,, r.L.¡
1