HomeMy WebLinkAboutDrainage Report 09.16.2022# areç zffiL* * æa*wry * p,øzrÆ &*ry" frxw *rev
5169 154 CouNrY Rono
GnnnELD CouNTY, ColonADo
September 16,2022
Rick Barth, P.E. 36749
Max Weiss, E.l.
Prepared by
ã5GM
I B WEST SIXTH STREET, SUITE 2OO
GleNwooo SPRTNGS, CO a I 60 I
970.945.1OO4
97O.945.5948 nax
GnRrIr¡-n COUNTY DRAITREr RTPCRT
Revreweo Bv
Rrcx BnRrH
Rick L B
by Rick L Barth
O=SGM,
Engr, Civ Svcs",
Barth
reviewed thls
11.01 15:25:12-06'00'
SGM Projecl#2022-356
Page 2 of 6
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This report is to present the drainage calculations to show compliance with the Garfield County
design criteria for a commercial parcel in an existing subdivision. The subject site is parcel 2395-
01 1-00-098 accessed by Coryell Road, a spur off CR 154 (old Highway 82) connected to Highway
82 at the Spring Valley Road intersection. The proposed development is approximately 1.96 acres
and has been previously developed with an existing detention pond on site.
The applicant is proposing to build a new mixed-use office/warehouse facility on their existing property
that is currently used as a storage yard for a stone-work business.
This constructable area of this parcel is in Zone C of FEMA FIRM community panel number 080205
1465 B effective on 01/03/86, and therefore there are no floodplain impacts. The current mapped
BFE is approximately 5914, well over 40 feet away from the construction area and well down the hill
as the main construction area platform is -5961. Therefore there are no floodplain impacts for this
site.
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Section 7 of the County development regulations provides the criteria for drainage design for sites
such as this. ln general, the rate of runoff from a site shall follow the 25-year design storm and historic
flows shall not be exceeded.
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The Rational Method is used to determine peak discharge rates for the site. The Rational Method is
widely applied to small catchments less than 90 acres, such as the applicant's parcel. The Rational
Method requires a runoff coefficient based on site imperviousness, the average rainfall intensity
associated with the time of concentration for a given site, and the area of the catchment.
Point precipitation frequency estimates are taken from NOAA Atlas 14, Volume 8, Version 2 for the
Basalt area. The NOAA data used in this study is included as an attachment to this report in the
Appendix. For the purposes of this study, the 1O-year event is analyzed as the "major" event. From
the NOAA data, a series of lntensity-Duration-Frequency (lDF) curves are generated, using the
Federal Highway Administration method detailed in HEC-12 (FHWA Hydraulic Engineering Circular
No. 12, Drainage of Highway Pavements). These IDF curves and associated information are included
in the Appendix.
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The existing site is mostly a gravel yard. A mild ridge exists east to west along the northern side of
the site. To the north of the ridge is vegetated space with an irrigation ditch leading to the existing
decorative pond in the northwest corner. For simplicity, the proposed work will not impact that portion
of the site and it is not included in our calculations.
The rest of the graveled site to the south of this ridgeline generally drains to a single ditch in the
southwest corner. We could not determine if that ditch was designed or simply constructed.
However, the site impacts include installing buried detention in that same general location so the area
over the ditch can be utilized for storage.
Page 3 of 6
There are no evidenced areas of surface runoff problems or erosion. Coryell Road, along the east
side, has little, if any drainage swale but likewise will receive little runoff from this site as the general
flow direction is to the west. On the west side a private drive exists with no notable drainage controls
or evidence of drainage problems.
For the purposes of adherence to the County design standards, and that there are no clear
downstream stormwater controls, we intend to detain the 2S-year design storm to the point of meeting
historic runoff values.
The NRCS Web Soil Survey of the site impact area classifies soils be Hydrologic Soil Group (HSG)
A,/8, and for the scope of the drainage design, the soil group will be considered as HSG B. The soil
types are Dahlquist-Southace complex, 25 to 50 percent slopes (HSG B), and Southace cobbly sandy
loam, 12 to 25 percent slopes (HSG A). A NRCS soil report map is included in the Appendix. These
soils are generally sandy, cobbly loam, lending themselves to good infiltration characteristics and use
of ground infiltrator/pond-type stormwater elements. There are no known impediments or soil layers.
Groundwater would appear to be very deep as the river is far below the site impact area. Historic
drainage patterns generally flow to the north with no notable channels or stormwater improvements
between the house site and the river.
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The applicant is proposing to build a structure for their office and warehouse space. The rest of the
site will be reconfigured with relatively similar grades but will include a few paved ADA parking
spaces, an entrance with a concrete apron, and re-configured gravel yard that will be utilized in
much the same manner as currently. Surface runoff will generally flow from northeast to southwest
as before with some inlets and surface flow from roof downspouts to minimize surface channeling
and sediment pickup. All flows will be collected and directed to an existing detention pond that will
allow infiltration but detain a sufficient volume for the 25-year storm to ensure the historic runoff
from a "native" condition is maintained. The northern and southeastern portions will maintain
"native" conditions and do not delineate into the basin described and will not be included in the
design.
5.1 Basin
The drainage basin consists of roof drainage from proposed structure along with impervious and
semi-pervious surfaces. Runoff will be routed to the west via subsurface piping and swales.
Drainage from the basin will be piped in PVC drain lines along with a swale the flows from the south
to west that will convey water to the existing detention pond, which will remain sized to completely
detain the excess runoff from developed conditions.
TotalArea (sf)lmp-Area (sf)Hist. 25-yr
Flowrate (cfs)
Prop. 25-yr Flowrate
(cfs) - Pre-Detention
Min. Detention Volume
(cuft)
62503 41516 1.34 2.97 1 165
6.S Rea* rnffieffiúeëâæns, *pæratâæn, &dt& ã*aånÉ*rs &me,e
Downspouts, area drains, stormwater pipes, and swales, along with the existing detention pond are
recommended to provide required stormwater detention on site. The components are indicated on
the civil plans prepared by SGM for the project. These are common items easily found in our region
Page 4 of 6
and easy to repair should the need occur. We recommend heat tape be installed wherever feasible
in the collector pipe to better ensure prevention of ice buildup.
The detention pond must be inspected and maintained yearly to remove sediment and debris that is
washed into it. Minimum inspection and maintenance requirements include the following: lnspect
chambers annually and after every storm exceeding 0.5 inches. Dispose of sediment, debrisitrash,
and any other waste material removed from the pond at suitable disposal sites and in compliance
with local, state, and federalwaste regulations.
The contents of this report and the accompanying design drawings shall not serve as the basis for
any third-party engineering design. lf site conditions that are considerably different from those
described in this report are encountered, SGM shall be notified in writing to evaluate the conditions.
lf the proposed construction is changed, SGM shall be notified in writing to evaluate the effect of the
changes with respect to the drainage system. The installer of the drainage system shall have prior
demonstrated knowledge of the Garfield County Land Use Code regulations and requirements.
Page 5 of 6
Appendix
Design Drawing with Basin Map
Calculation sheet
NOAA Atlas 14 Precipitation Data for location in Garfield County, Colorado
NRCS Web Soil Survey
FEMA FIRM
Page 6 of 6
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Basins1 - Dev 1- H¡stSite - 25Basin'l425,62 L038.49 -6L2.87776.77 1078.56 30r.791071.06 1118.64 -47.581320.98 1158.72 16¿261455.2t1 1198.80 256.61r72t.79 L23a.8A 4A2.9!1884.64 1278.95 605.692028.18 1319.03 709.152155.s4 1359.11 796.432269.23 1399.19 870.04237L.27 1439.27 932.002463.29 1479.34 983.942546.64 Lstg.4z LO27.Z22622.46 1559.50 1062.962691.66 1599.58 1092.092755.06 1639.66 1115.402813.30 1679.73 1133.572866.98 1719.81 1147.172916.58 1759.89 1156.692962.52 L799.97 !162.55ffiffiffi3044.86 L880.L2 tt64.743081.87 1920.20 1161.663116.43 r.960.28 L156.L53148.78 2000.36 11¿18.433L79.L1 2040.44 t738.673207.58 2080.52 1127.073234.36 2L2059 71L3.771.00 7.342.00 6.703.00 6.L64.00 5.705.00 5.026.00 4.957.OO 4.648.00 4.379.00 4.1310.00 3.9111.00. 3.7212.00 3.5¿¡13,00 3.3814.00 3.2315.00 3.0916.00 2.9717.00 2.8518.00 2.7519.00 2.6520.00 2.ss21.00 2.4722.00 2.3923.00 2.3724.OO 2.U2s.00 2.L726.00 2.L727.ú 2.0528,00 1.99Târget Volume by FAA Method_-.,--*..--..--}Rainfall lntensity-Durat¡on-Frequency (lDF) in Garfield County;39.4743", -LO7.2746"Íor Glenwood Springs,Return Per Pl / inlhr2-yt 0,494Fyr 0.688.10-r 0.83825-y¡' 1.03s(}.yr 1.16100-yr L.Ze*
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NOAA Atlas 14, Volume 8, Version 2
Location name: Glenwood Springs, Golorado,
USA*
Latitude: 39.47 43", Longitude: -107 "27 46'
Elevation: 5945.46 ft**
'source: ESRI MaPs
** source: USGs
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POINT PRECIPITATION FREQUENCY ESTIMATES
Sanja Perlca, Deborah Mart¡n, Sandra Pavlovic, lshani Roy, M¡chael st. Laurent, carl Trypaluk, Dale
Unruh, Michael Yekta, Geoffery Bonnin
NOAA, Nal¡onal Weather Serv¡ce, Silver Spring, Maryland
PF tabular I PF grap-bçAll Maps-e-Aeiaig
PF tabular
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PF graphical
PDS-based po¡nt prec¡pitation freque ncy est¡mates with 90% confidence ¡ntervals (in i nches 1
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given duratión and average recurrence interval) w¡ll be gréater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
ãhecked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information
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National Oceanic and Atmospheds ¿drnldslrat¡on
National Weather Service
National Water Center
1325 East West Highway
Silver Spring, MD 20910
Questions?: HDSC.Quest¡ons@noaa. gov
Ðisclaimer
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USDA
:
United States
Department of
Agriculture
NRCS
Natural
Resources
Conservation
Service
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
Aspen-Gypsum Area,
Golorado, Parts of Eagle,
Garfield, and Pitkin
Gounties
August 10,2021
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 officials, 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 governments may impose
special restrictions on land use or land treatment. Soil surveys identify 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
cases. Examples include soil quality assessments (http://www.nrcs.usda.govlwps/
portal/nrcs/mainlsoils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www nrcs. usda. govlwps/portal/nrcs/detail/soils/contactus/?
cid=nrcs1 42p2*05395 1 ).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable 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 official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, colo¡ national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, 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
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at(202)720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office 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 equalopportunity
provider and employer.
3
Gontents
Preface......
How Soil Surveys Are Made...
Soil Map....
SoilMap.....
Legend.......
Map Unit Legend.......
Map Unit Descriptions
Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin
Counties.....
2B-Dahlquist-Southace complex, 25 to 50 percent s|opes...........
98-southace cobbly sandy loam,12 to 25 percent s|opes...........
References
.2
..5
.B
..9
10
12
12
14
14
16
18
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the suface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soilsurvey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area" Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units)"
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
Custom Soil Resource Report
scientists classified and named the soils in the survey atea, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. lf intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. lnterpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
6
Custom Soil Resource Report
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
7
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.
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Custom Soil Resource ReportMAP LEGENDMAP INFORMATIONThe soil surveys that comprise your AOI were mapped at1:24,0O0.Please rely on the bar scale on each map sheet for mapmeasurements.Source of Map: Natural Resources Conservation Serv¡ceWeb Soil Survey URL:Coordinate System: Web Mercator (EPSG:3857)Maps from the Web Soil Survey are based on the Web Mercatorprojection, which preserves direction and shape but distortsdistance and area. A projection 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 version date(s) listed below.Soil Survey Area: Aspen-Gypsum Area, Colorado, Parts ofEagle, Garfield, and Pitkin CountiesSurvey Area Data: Version 11, Jun 5, 2020Soil map units are labeled (as space allows) for map scales1:50,000 or larger.Date(s) aerial images were photographed: Sep 24, 201$-Nov2,2015The orthophoto or other base map on which the soil lines werecompiled and digitized probably differs from the backgroundArea of lnterest (AOl)H Spoil Areaü Stony Spotffi VeryStonySpot$ WetSpot& Other.- Special Line FeaturesWater FeaturesStreams and CanalsTransportation*r Railsc,gl lnterstate Highwayse¡¡d US Routes. rÌ Major RoadsLocal RoadsBackgroundI Aerial PhotographyArea of lnterest (AOl)Soils[] Soil Map Unit PolygonsÊrr So¡l Map Unit LinesE Soil Map Unit PointsSpecial Point Features{$¡ BlowoutW Borrow Pitffi Clay Spot* Closed Depressionþ6 Gravel Pit.! Gravelly Spotß Landfìll* Lava Flowd!å Marsh or swamp# M¡ne or Quarry6 Miscellaneous Waterffi Perennial Water\S. Rock OutcropS Saline Spotþ: Sandy SpotSeverely Ëroded Spot& Sinkholeþ Slide or Slipø Sodic SpotWarning: Soil Map may not be valid at this scale.Enlargement of maps beyond the scale of mapping can causemisunderstanding of the detail of mapping and accuracy of soilline placement. The maps do not show the small areas ofcontrasting so¡ls that could have been shown at a more detailedscale.10
MAP LEGENDCustom Soil Resource ReportMAP INFORMATIONimagery displayed on these maps. As a result, some minorofunit boundariesbe evident.11
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 propedies 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 impracticalto make enough observations to identify all the 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,
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
28 Dahlquist-Southace complex,
25 to 50 percent slopes
2.O 87.2o/o
98 Southace cobbly sandy loam,
12 lo 25 percent slopes
0.3 12.8o/o
Totals for Area of lnterest 2.3 100.0%
12
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 so/ senes. Except for
differences in texture of the surface layer, 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 layer, 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 assocrafion 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 are 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.
13
Custom Soil Resource Report
Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin
Gounties
28-Dahlquist-Southace complex, 25 to 50 percent slopes
Map Unit Setting
National map unit symbol: iqSg
Elevation: 6,200 to 7,400 feet
Mean annualprecipitation: 12to 16 inches
Mean annual airtemperature: 42 to 46 degrees F
Frost-free period: 105 to 115 days
Farmland classification; Not prime farmland
Map Unit Gomposition
Dahlquist and similar so/s:40 percent
Southace and similar sols; 35 percent
Minor components: 25 percent
Estimates are based on observations, descriptions, and fransecfs of the mapunit.
Description of Dahlquist
Setting
Landform: Alluvial fans, terraces
Landform position (th ree-di mensional); Riser
Down-slope sh ape : Linear
Across-s/ope sh ape : Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 6 inches: cobbly sandy loam
H2 - 6 to 13 inches.' very cobbly sandy clay loam
H3 - 13 to 23 inches.' very cobbly sandy loam
H4 - 23 to 60 inches: extremely cobbly sandy loam
Properties and qualities
S/ope;25 to 50 percent
Depth to restrictive feature: More than B0 inches
Drainage c/ass; Well drained
Runoff class; High
Capacity of the most limiting layer to transmit water (Ksat); Moderately high to high
(0.20 to 2.00 in/hr)
Depth to water fable; More than B0 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum content: 15 percent
Available water capacify: Low (about 3.2 inches)
lnterpretive groups
Land capability classification (irrigated) : None specified
Land capability classification (nonirrigated): 7 e
Hydrologic Soil Group: B
Ecological sife; R04BAY303CO
Other vegetative classificafion; LOAMY SLOPES (null_31)
Hydric so/ rafing; No
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Custom Soil Resource Report
Description of Southace
Setting
Landform: Alluvial fans, terraces
La n dfo rm p o s it i o n (t h re e -d i m ensional,) : R ise r
Down-slope sh ape : Linear
,Across-s/op e sh ape : Linear
Parent material: Mixed alluvium
Typical profile
H1 - 0 to 10 inches.' very stony sandy loam
H2 - 10 to 22 inches; extremely stony sandy loam
H3 - 22 to 60 inches; extremely stony loamy coarse sand
Properties and qualities
S/ope;25 to 50 percent
Depth to restrictive feature: More than B0 inches
Drainage c/ass: Well drained
Runoff class; Medium
Capacity of the most limiting layer to transmit water (Ksat); Moderately high to high
(0.60 to 6.00 in/hr)
Depth to water table: More than B0 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum content: 10 percent
Maximum salinity: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm)
Available water capacity: Very low (about 2.0 inches)
lnterpretive groups
Land ca pabil ity cl assification (i rrig ated); None specified
Land capability classification (nonirrigated) : 7 s
Hydrologic Soil Group: A
Ecological s/fe; R04BAY2B7 CO
Other vegetative cl assificafion: Stony Foothills (n ull_B 1 )
Hydric so/ rafing; No
Minor Components
Other soils
Percent of map unit: 10 percent
Hydric so/ rafing: No
Gypsiorthids
Percent of map unit: 10 percent
Hydric sori rafing; No
Rock outcrop
Percent of map unit: 5 percent
Hydric so/ rafing: No
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Custom Soil Resource Report
98-southace cobbly sandy loam, 12to 25 percent slopes
Map Unit Setting
National map unit symbol: jqTY
Elevation: 6,000 to 7,000 feet
Mean annual precipitation: 14lo 16 inches
Mean annual airtemperature: 42 to 46 degrees F
Frost-free period: 95 to 105 daYs
Farmland classification; Not prime farmland
Map Unit Composition
Southace and similar so/s: 90 percent
Minor components: 10 percent
Estimates are based on obseruations, descriptions, and transects of the mapunit.
Description of Southace
Setting
Landform: Alluvial fans, mountains, terraces
Landform position (three-dimensional): Lower third of mountainflank, tread
Down-slope shape : Concave
Across-s/ope shape: Linear
Parent material: Alluvium derived from sandstone and shale
Typical profile
H1 - 0 to 3 inches: cobblY sandY loam
H2 - 3 to 14 inches: gravellY loam
H3 - 14 to 26 inches.' very gravelly loam
H4 - 26 to 60 inches.' very cobbly fine sandy loam
Properties and qualities
S/ope: 12to 25 percent
Depth to restrictive feature: More than B0 inches
Drainage c/ass: Well drained
Runoff class; 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 B0 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum content: 10 percent
Maximum salinity: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm)
Available water capacity: Low (about 5.3 inches)
lnterpretive groups
Land capability cl assification (i rrig ated); None specified
Land capability classification (nonirrigated): 7s
Hydrologic Soil Group: A
Ecological slfe; R04BAY303CO
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Custom Soil Resource Report
Other vegetative classificaflon: LOAMY SLOPES (null_31)
Hydric so/ rafing: No
Minor Components
Other soils
Percent of map unit: 10 percent
Hydric so/ raftng; No
17
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 D2487-00"
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S" Fish and Wildlife
Service FWS/OBS-79/31 .
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18,2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soilsurvey manual. SoilConservation Service.
U.S. Deparlment of Agriculture Handbook 18. http:llwwwnrcs.usda.gov/wps/porial/
nrcs/detail/national/soils/?cid=nrcs1 42p2*054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577
Soil Survey Staff. 2010. Keys to soiltaxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www.nrcs.usda.gov/wpslportal/nrcs/detail/national/soils/?cid=nrcs142p2*053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States'Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Watenrvays Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
h om el?cid = nr es 1 42p2 _0 5337 4
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http:llwww.nrcs.usda.govlwpslportal/nrcs/
detail/national/landuse/rangepasture/?cid=stelprdb I 043084
18
Custom Soil Resource Report
United States Department of Agriculture, Natural Resources Conservation Service.
National soil su rvey h a nd book, title 430-Vl. http ://www n rcs. usda. g ov/wps/porta l/
nrcs/detail/soils/scientists/?cid=nrcs 1 42p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http:/iwvwv.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcsi 42 p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961 . Land
capability classification. U.S. Department of Agriculture Handbook 210. hllp,,ll
www. nrcs. usda. gov/l nternetlFSE_DOCUMENTS I nrcsl 42p2_052290. pdf
19
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