HomeMy WebLinkAbout20071116.tiff Soils Information
Excerpts from the Soil Survey of Weld County, Southern Part (SCS, 1980) are provided
in this Appendix. Most of the soils in the proposed areas are aquolls, aquents, and
bankard sandy loam that commonly occur on bottomlands, floodplains, and natural
drainageways. These are generally deep, poorly drained soils that formed in recent
alluvium.
These soils are primarily suited for pasture, rangeland, and wildlife habitat. They are
well suited to reestablishment of grasses as proposed in the Reclamation Plan. If
recommended by SCS, soil samples will be subjected to agricultural testing to evaluate
fertilizer requirements.
The affected lands within the permit area contain many types of soils. The U.S.
Department of Agriculture Soil Conservation Service delineates the extents of, and
characterizes each soil type in a soil survey. The Soils Map, enclosed at the end of this
Exhibit, illustrates where these soils are present within the permit area. The following are
descriptions of the soils found in the area.
3—Aquolls and Aquents,gravelly substratum
This nearly level map unit is on bottomlands and floodplains of all the major streams in
the survey area. Aquolls, which have a dark colored surface layer,make up about 60
percent of the unit. Aquents, which have a lighter colored surface layer, make up about
35 percent. About 5 percent is Aquepts and Bankard sandy loam.
These are deep,poorly drained soils that formed in recent alluvium. No one pedon is
typical. Commonly the soils have a mottled,mildly alkaline to moderately alkaline loamy
or clayey surface layer and underlying material and are underlain by sand or sand and
gravel within 48 inches. In places they have a gleyed layer in the underlying material.
Most of the acreage is subject to flooding. The water table is at or near the surface early
in spring and recedes to as deep as 48 inches late in fall in some years.
These soils are used for rangeland and wildlife habitat. Some small area have been
reclaimed by major drainage and leveling and are used for irrigated crops.
The potential native vegetation is dominated by alkali sacaton, switchgrass, and western
wheatgrass. Saltgrass, sedge, rush and alkali bluegrass are also prominent. Potential
production ranges from 3000 pounds per acre in favorable years to 2000 pounds in
unfavorable years. As range condition deteriorates, the switchgrass, alkali sacaton, and
western wheatgrass decrease and saltgrass, sedge and rush increase.
Management of vegetation should be based on taking half and leaving half of the total
annual production. Seeding is difficult and costly because numerous tillage practices are
required to eliminate the saltgrass sod. Switchgrass, western wheatgrass, alkali sacaton,
tall wheatgrass, and tall fescue are suitable for seeding. They can be seeded into a clean,
2007-1116
firm seedbed. Seedbed preparation usually requires more than 1 year to eliminate the
saltgrass sod. A grass drill should be used. Seeding early in spring has proven most
successful.
Wetland wildlife, especially waterfowl, utilizes this unit. The wetland plants provide
nesting and protective cover, as well as food. The nearby irrigated cropland, where
wildlife obtain much of their food and find protective cover, makes this unit valuable to
both wetland and openland wildlife.
Open land wildlife, especially pheasant, uses this unit for cover and nesting. Deer find
excellent cover in some areas. These valuable wildlife areas should be protected from
fire and fenced to prevent encroachment and overuse by livestock. They should not be
drained.
These soils have good potential as a source of sand and gravel. Capability subclass Viw;
Salt Meadow range site.
8—Ascalon loam, 0-1 %slopes
This is a deep, well drained soil on terraces at elevation of 4500 to 4900 feet. It formed
in alluvium deposited by the major rivers in the survey area. Included in mapping are
small areas where sand and gravel are with in a depth of 60 inches. Also included are
small areas of soils that have a clay loam subsoil.
Typically, the surface layer of this Ascalon soil is brown loam aboutl0 inches thick. The
subsoil is brown and yellowish brown sandy clay loam about 15 inches thick. The
substratum to a depth 60 inches is calcareous sandy loam.
Permeability is moderate. Available water capacity is high. The effective rooting depth is
60 inches or more. Surface runoff is slow, and the erosion hazard is low.
This soil is used almost entirely for irrigate crops. It is suited to all crops commonly
grown in the area, including corn, sugar beets, beans alfalfa, small grain,potatoes, and
onion. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by
corn, corn for silage, sugar beets, small grain, or beans. Few conservation practices are
needed to maintain top yields.
All methods of irrigation are suitable,but furrow irrigation is the most common.
Barnyard manure and commercial fertilizer are needed for top yields.
Windbreaks and environmental plantings are generally well suited to this soil. Cultivation
to control competing vegetation should be continued for as many years as possible
following planting. Trees that are best suited and have good survival are Rocky Mountain
juniper, eastern redcedar, ponderosa pine, Siberian elm, Russian-olive, and hackberry.
The shrubs best suited are skunkbush sumac, lilac, Siberian peashrub, and American
plum.
Wilildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many non-game species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture.
This soil has good potential for urban and recreational development. Increased population
growth in the survey area has resulted in increased homesite construction. The chief
limiting soil features for urban
development are the shrink-swell potential of the subsoil as it wets and dries and the
limited ability of this soil to support a load. Septic tank absorption fields function
properly, but community sewage systems should be provided if the population density
increases. Because of the moderately rapid permeability of the substratum, sewage
lagoons must be sealed. Lawns, shrubs, and trees grow well. Capability class I irrigated.
9-Ascalon Loam, 1-3%slopes
This is a deep, well drained soil on terraces at elevations of 4500 to 4900 feet. It formed
in alluvium deposited by the major rivers in the survey area. Included in mapping are
small areas where sand and gravel are within a depth of 60 inches. Also included are
small areas of soils that have a clay loam subsoil.
Typically the surface layer of this Ascalon soil is brown loam about 10 inches thick. The
subsoil is brown and yellowish brown sandy clay loam about 15 inches thick. The
substratum to a depth of 60 inches is calcareous sandy loam.
Permeability is moderate. Available water capacity is high. The effective rooting depth is
60 inches or more. Surface runoff is medium, and the erosion hazard is low.
This soil is used almost entirely for irrigated crops. It is suited to all crops commonly
grown in the area, including corn, sugar beets, beans, alfalfa, small grain,potatoes, and
onions. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by
corn, corn for silage, sugar beets, small grain, or beans. land leveling, ditch lining, and
installing pipelines may be needed for proper water application.
All methods of irrigation are suitable,but furrow irrigation is the most common.
Barnyard manure and commercial fertilizer are needed for top yields.
Windbreaks and environmental plantings of trees and shrubs commonly grown in the area
are generally well suited to this soil. Cultivation to control competing vegetation should
be continued for as many years as possible following planting. Trees that are best suited
and have good survival are Rocky Mountain juniper, eastern red cedar, ponderosa pine,
Siberian elm, Russian-olive, and hackberry. The shrubs best suited are skunkbush sumac,
lilac, Siberian peashrub, and American plum.
Wildlife is an important use of this soil. The cropland areas provide favorable habitat for
ring-necked pheasant and mourning dove. Many nongame species can be attracted by
establishing areas for nesting and escape cover. For pheasants, undisturbed nesting cover
is essential and should be included in plans for habitat development, especially in areas of
intensive agriculture.
This soil has good potential for urban and recreational development. Increased population
growth in the survey area has resulted in increased homesite construction. The chief
limiting soil features for urban
development are the shrink-swell potential of the subsoil as it wets and dries and the
limited ability of this soil to support a load. Septic tank absorption fields function
properly,but community sewage systems should be provided if the population density
increases. Because of the moderately rapid permeability of the substratum, sewage
lagoons must be sealed. Lawns, shrubs, and trees grow well. Capability subclass lie
irrigated.
10-Bankard sandy loam, 0-3%slope
This is a deep, somewhat excessively drained soil on flood plains atelevations of 4450 to
5000 feet. It formed in stratified recent alluvium along streams and rivers. Included in
mapping are numerous sand and gravel bards and small areas of noncalcareous soils.
Typically the surface layer of this Bankard soild is brown sandy loam about 4 inches
thick. The underlying material to a depth of 60 inches is pale brown calcareous sand
stratified with thin lenses of sandy loam, loam, and fine gravel.
Permeability is moderately rapid. Available water capacity is low. The effective rooting
depth is 60 inches or more. Surface runoff is slow, and the erosion hazard is low.
This soil is suited to limited cropping. It is sandy and subject to flooding. Pasture is the
best use. Tall wheatgrass, tall fescue, and annual sweeclover are some of the most
suitable crops. Light, frequent irrigation by furrows and flooding is best. Commercial
fertilizer improves the amount and value of forage produced.
The potential native vegetation is dominated by switchgrass, indiangrass, sand bluestem,
sand reedgrass, sideoats grama, needleandthread, and blue grama. Much of this range site
includes other soils and vegetation in such a complex pattern that it is difficult to map
them separately. Potential production ranges from 2500 pounds per acre in favorable
years to 1500 pounds in unfavorable years. As range condition deteriorates, the tall and
mid grasses decrease; blue grama, sand dropseed, and forbs increase; and forage
production drops. Undesirable weeds and annuals invade the site as range condition
becomes poorer.
Management of vegetation should be based on taking half and leaving half of the total
annual production. Seeding is desirable only in areas large enough to interseed or to
prepare a seedbed. Switchgrass, sand bluestem, sand reedgass, sideoats grama, little
bluestem,blue grama,pubescent wheatgrass, and intermediate wheatgrass are suitable for
seeding. This soil can be seeded by using an interseeder or a firm clean sorghum stubble.
A grass drill is required. Seeding early in spring has proven most successful.
This soil is generally not suited to the establishment and growth of tress and shrubs.
Onsite investigation is needed to determine feasibility and possible tree and shrub
species.
Wildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture. Rangeland wildlife, for example, deer and
antelope, can be attracted by managing livestock grazing and reseeding where needed.
This soil is not suited to urban or recreational development because of the flood hazard.
Capability subclass IVw irrigated, VIw nonirrigated; Sandy Bottom land range site.
19- Colombo Clay Loam, 0-1 %slopes
This is a deep,well drained soil on flood plains and terraces at elevations of 4600 to 4780
feet. It formed in stratified calcareous alluvium. Included in mapping are small areas of
soils that have a loam surface layer and some small leveled areas.
Typically the surface layer of this Colombo soil is dark grayish brown clay loam about 14
inches thick. The upper 7 inches of the underlying material is pale brown stratified clay
loam and loam. The lower part to a depth of 60 inches is very pale brown loam stratified
with thin lenses of fine sand,medium sand, and clay loam.
Permeability is moderate. Available water capacity is high. The effective rooting depth is
60 inches or more. Surface runoff is slow, and the erosion hazard is low.
In irrigated areas this soil is suited to crops commonly grown in the area such as corn,
sugar beets,beans, alfalfa, onions and potatoes.
All methods of irrigation that are common to the area are used. Borders are suitable for
small grain, alfalfa, and pasture. Furrow irrigation is used for row crops. Crops respond to
application of nitrogen and phosphorus.
Windbreaks and environmental plantings of trees and shrubs commonly grown in the area
are generally well suited to this soil. Cultivation to control competing vegetation should
be continued for as many years as possible following planting. Trees that are best suited
and have good survival are Rocky Mountain juniper, eastern redcedar, ponderosa pine,
Siberian elm, Russian-olive, and hackberry. The shrubs best suited are skunkbush sumac,
lilac, Siberian peashrub, and American plum.
Wildlife is an important secondary use of this soil. Ring-necked pheasant, mourning
dove, and many nongame species can be attracted by establishing areas for nesting and
escape cover. For pheasants, undisturbed nesting cover is essential and should be
included in plans for habitat development, especially in areas of intensive agriculture.
Where this soil is on flood plains and is susceptible to flooding it has poor potential for
urban and recreational development. On the higher terraces the potential is fair. Dwelling
and road designs need to be modified to increase the capacity of the soil to support a load
and to protect it against frost action. Capability subclass Ilw irrigated.
21 —Dacono Clay Loam, 0-1 %slopes
This is a deep, well drained soil on terraces at elevations of 4550 to 4970 feet. It formed
in mixed alluvium. Included in mapping are small, long and narrow areas of sand and
gravel deposits and some small, leveled areas. Typically, the surface layer of this Dacono
soil is grayish brown clay loam about 12 inches thick. The subsoil is grayish brown clay
loam about 15 inches thick. The substratum is very gravelly sand.
Permeability is moderately slow. Available water capacity is moderate. The effective
rooting depth is 20 to 40 inches. Surface runoff is slow, and the erosion hazard is low.
This soil is used almost entirely for irrigated crops. It is suited to all crops commonly
grown in the area, including corn, sugar beets,beans, alfalfa, small grain, potatoes, and
onions. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by
corn, corn for silage, sugar beets, small grain, or beans. Generally, such characteristics as
high clay content or a rapidly permeable substratum slightly restrict some crops.
All methods of irrigation are suitable,but furrow irrigation is the most common. Proper
irrigation water management is essential. Barnyard manure and commercial fertilizer are
needed for top yields.
Windbreaks and environmental plantings of trees and shrubs commonly grown in the area
are generally well suited to this soil. Cultivation to control competing vegetation should
be continued for as many years as possible following planting. Trees that are best suited
and have good survival are Rocky Mountain juniper, eastern redcedar, ponderosa pine,
Siberian elm, Russian-olive, and hackberry. The shrubs best suited are skunkbush sumac,
lilac, Siberian peashrub, and American plum.
Openland wildlife, such as pheasant, mourning dove, and cottontail are best suited to this
soil. Wildlife habitat development, including tree and shrub plantings and grass plantings
to serve as nesting areas, should be successful without irrigation during most years.
Under irrigation, good wildlife habitat can be established,benefiting many kinds of
openland wildlife.
This soil has only fair potential for urban and recreational development. Above the sand
and gravel substratum the soil has moderate slow permeability. These features create
problems in dwelling and road construction. Excessive permeability in the substratum can
cause contamination of the ground water supply from septic tank leach fields. Sewage
lagoons need to be lined. Capability subclass Its irrigated.
31 -Kim Loam, 0-1 %slopes
This is a deep, well drained soil on smooth plains and alluvial fans at elevations of 4900
to 5250 feet. It formed in mixed eolian deposits and parent sediment from a wide variety
of bedrock. Included in mapping re small areas of soils that have loamy sand underlying
material.
Typically, the surface layer is brown and pale brown about 12 inches "'--" thick. The
upper 30 inches of the underlying material is pale brown loam. The lower part to a depth
of 60 inches is pale brown fine sandy loam.
Permeability is moderate. Available water capacity is high. The effective rooting depth is
60 inches of more. Surface runoff is slow, and the erosion hazard is low.
This soil is used almost entirely for irrigated crops. It is suited to all corps commonly
grown in the area, including corn, sugar beets,beans, alfalfa, small grain, potatoes, and
onions. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by
corn, corn for silage, sugar beets, small grain, or beans. Very few conservation practices
are needed to maintain top yields.
All methods of irrigation are suitable,but furrow irrigation is the most common.
Barnyard manure and commercial fertilizer are needed for top yields.
Windbreaks and environmental plantings of trees and shrubs commonly grown in the area
are generally well suited to this soil. Cultivation to control competin vegetation shoulc be
continued for as many years as possible following planting. Trees that are best suited and
have good survival are Rocky Mountain juniper, eastern redcedar, ponderosa pine,
Siberian elm, Russian-olive, and hackberry. The shrubs best suited are skunkbush sumac,
Siberian peashrub, lilac, and American plum.
Wildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture.
This soil has good potential for urban and recreational development. Increased population
growth in the survey area has resulted in increased homesite construction. The chief
limiting feature for urban development and road construction is the limited capacity of
the soil to support a load. Septic tank absorption fields function properly, but community
sewage systems should be provided if the population density increases. Because of the
permeability of the substratum, sewage lagoons must be sealed. lawns, shrubs, and trees
grow well. Capability class I irrigated.
32-Rim loam, 1-3%slopes
This is a deep, well-drained soil on smooth plains and alluvial fans at elevations of 4900
to 5250 feet. It formed in mixed eolian deposits and parent sediment from a wide variety
of bedrock. Included in mapping re small areas of soils that have loamy sand underlying
material.
Typically, the surface layer is brown and pale brown about 12 inches thick. The upper 28
inches of the underlying material is pale brown loam. The lower part to a depth of 60
inches is pale brown fine sandy loam.
Permeability is moderate. Available water capacity is high. The effective rooting depth is
60 inches of more. Surface runoff is medium, and the erosion hazard is low.
In irrigated areas this soil is suited to all crops commonly grown in the area, including
corn, sugar beets, beans, alfalfa, small grain,potatoes, and onions. An example of a
suitable cropping system is 3 to 4 years of alfalfa followed by corn, corn for silage, sugar
beets, small grain, or beans. land leveling, ditch lining, and installing pipelines may be
needed for proper water applications.
All methods of irrigation are suitable, but furrow irrigation is the most common.
Barnyard manure and commercial fertilizer are needed for top yields.
In nonirrigated areas this soil is suited to winter wheat, barley, and sorghum. Most of the
acreage is planted to winter what and is summer followed in alternate years to allow
moisture accumulation. Generally precipitation is too low for beneficial use of fertilizer.
Stubble mulch farming, striperopping, and minimum tillage are needed to control soil
blowing and water erosion. Terracing also may be needed to control water erosion.
The potential native vegetation is dominated by blue grama. Several mid grasses, such as
western wheatgrass and needleandthread, are also present. Potential production ranges
from 1600 pounds per acre in favorable years to 1000 pounds in unfavorable years. As
range condition deteriorates, the mid grasses decrease; blue grama, buffalograss,
snakeweed, yucca, and fringed sage increase; and forage production drops. Undesirable
weeds and annuals invade the site as range condition becomes poorer.
Management of vegetation on this soil should be based on taking half and leaving half of
the total annual production. Seeding is desirable if the range is in poor condition. Sideoats
grama, little bluestem, western wheatgrass, blue grama,pubescent wheatgrass, and
crested wheatgrass are suitable for seeding. The grass selected should meet the seasonal
requirements of livestock. It can be seeded into a clean, firm sorghum stubble, or it can
be drilled into a firm prepared seedbed. Seeding early in spring has proven most
successful.
Windbreaks and environmental plantings of trees and shrubs commonly grown in the area
are generally well suited to this soil. Cultivation to control competing vegetation should
be continued for as many years as possible following planting. Trees that are best suited
and have good survival are Rocky Mountain juniper, eastern redcedar, ponderosa pine,
Siberian elm, Russian-olive, and hackberry. The shrubs best suited are skunkbush sumac,
Siberian peashrub, lilac, and American plum.
Wildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture.
This soil has good potential for urban and recreational development. Increased population
growth in the survey area has resulted in increased homesite construction. The chief
limiting feature for urban development and road construction is the limited capacity of
the soil to support a load. Septic tank absorption fields function properly, but community
sewage systems should be provided if the population density increases. Because of the
permeability of the substratum, sewage lagoons must be sealed. Lawns, shrubs, and trees
grow well. Capability subclass lie irrigated, IVe nonirrigated; Loamy Plains range site.
34-Kim Loam, 5-9%slopes
This is a deep well drained soil on plains and alluvial fans at elevations of 4900 to 5250
feet. It formed in mixed eolian deposits and parent sediment from a wide variety of
bedrock. Included in mapping are small areas of soils that have loamy sand underlying
material.
Typically the surface layer is brown and pale brown loam about 10 inches thick. The
upper 25 inches of the underlying material is pale brown loam. The lower part to a depth
of 60 inches is pale brown fine sandy loam.
Permeability is moderate. Available water capacity is high. The effective rooting depth is
60 inches or more. Surface runoff is rapid, and the erosion hazard is moderate. This soil
is suited to limited cropping. Intensive cropping is hazardous because of erosion. The
cropping system should be limited to such close grown crops as alfalfa, wheat, and
barley. This soil also is suited to irrigated pasture. A suitable cropping system is 3 to 4
years of alfalfa followed by 2 years of corn and small grain and alfalfa seeded with a
nurse crop.
Close grown crops can be irrigated from closely spaced contour ditches or sprinklers.
Contour furrows or sprinklers should be used for new crops. Applications of nitrogen and
phosphorus help in maintaining good production.
The potential native vegetation is dominated by blue grama. Sideoats grama, little
bluestem, western wheatgrass, and sedge are also prominent. Potential production ranges
from 1800 pounds per acre in favorable years to 1500 pounds in unfavorable years. As
range condition deteriorates, the sideoats grama and little bluestem decrease; forage
production drops; and blue grama,buffalograss, and several perennial forbs and shrubs
increase. Undesirable weeds and annuals invade the site as range condition becomes
poorer.
Management of vegetation should be based on taking half an leaving half of the total
annual production. Seeding is desirable if the range is in poor condition. Sideoats grama,
little bluestem,western wheatgrass, and pubescent wheatgrass are suitable for seeding.
The grass selected should meet the seasonal needs of livestock. It can be seeded into a
clean, firm sorghum stubble, or it can be drilled into a firm prepared seedbed. Plowing
and drilling on the contour minimize runoff and soil losses. Seeding early in spring has
proven most successful.
Windbreaks and environmental plantings are generally well suited to this soil. Cultivation
to control competing vegetation should be continued for as many years as possible
following planting. Trees that are best suited and have good survival are Rocky Mountain
juniper, eastern redcedar, ponderosa pine, Siberian elm, Russian-olive, and hackberry.
The shrubs best suited are skunkbush sumac, lilac, Siberian peashrub, and American
plum.
Wildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture. Rangeland wildlife, for example, the
pronghorn antelope, can be attracted by developing livestock watering facilities,
managing livestock grazing, and reseeding where needed.
This soil has good potential for urban and recreational development. Increased population
growth in the survey area has resulted in increased homesite construction. The chief limiting
soil feature for urban development and road construction is th elimited capacity of this soil
to support a load. Septic tank absorption fields function properly,but community sewage
systems should be provide if the population density increases. Because of the
permeability of the substratum, sewage lagoons must be sealed. Lawns, shrubs, and trees
grow well. Capability subclass IVe irrigated, Vie nonirrigated; Loamy Plains range site.
39-Nunn Loam, 0-1 %slopes
This is a deep, well drained soil on terraces at elevations of 4550 to 5000 feet. It formed
in mixed alluvium. Included in mapping are small, long and narrow areas of sand and
gravel deposits and small areas of soil that are subject to occasional flooding. Some small
leveled areas are also included.
Typically the surface layer of this Nunn soil is grayish brown loam about 12 inches thick.
The subsoil is light brownish gray clay loam about 12 inches thick. The upper part of the
substratum is light brownish gray clay loam. The lower part to a depth of 60 inches is
brown sandy loam.
Permeability is moderately slow. Available water capacity is high. The effective rooting
depth is 60 inches or more. Surface runoff is slow, and the erosion hazard is low.
This soil is used almost entirely for irrigated crops. It is suited to all crops commonly
grown in the area, including corn, sugar beets,beans, alfalfa, small grain, potatoes, and
onions. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by
corn, corn for silage, sugar beets, small grain, or beans. Few conservation practices are
needed to maintain top yields.
All methods of irrigation are suitable,but furrow irrigation is the most common.
Barnyard manure and commercial fertilizer are needed for top yields.
Windbreaks and environmental plantings of trees and shrubs commonly grown in the area
are generally well suited to this soil. Cultivation to control competing vegetation should
be continued for as many years as possible following planting. Trees that are best suited
and have good survival are Rocky Mountain juniper, eastern red cedar, ponderosa pine,
Siberian elm, Russian-olive, and hackberry. The shrubs best suited are skunkbush, lilac,
Siberian peashrub, and American plum.
Wildlife is an important secondary used of this soil.The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing-areas for nesting and escape cover. For pheasants undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture.
This soil has fair to poor potential for urban development. It has moderate to high shrink
swell, low strength, and moderately slow permeability. These features create problems in
dwelling and road construction. Those areas that have loam or sandy loam in the lower
part of the substratum are suitable for septic tank absorption fields and foundations. Some
areas are adjacent to streams and are subject to occasional flooding. This soil has fair
potential for such recreational development as camp and picnic area and playgrounds.
Capability class I irrigated.
41—Nunn Clay Loam, 0-1%slopes
This is a deep, well-drained soil on terraces and smooth plains at elevations of 4550 to
5150 feet. It formed in mixed alluvium and eolian deposits. Included in mapping are
small, long and narrow areas of sand and gravel deposits and small areas of soils that are
subject to occasional flooding. Some small, leveled areas are also included.
Typically, the surface layer of this Nunn soil is grayish brown clay loam about 9 inches
thick. The subsoil is light brownish gray clay loam about 14 inches thick. The upper part
of the substratum is clay loam. The lower part to a depth of 60 inches is sandy loam.
Permeability is moderately slow. Available water capacity is high. The effective rooting
depth is 60 inches or more. Surface runoff is slow, and the erosion hazard is low.
This soil is used almost entirely for irrigated crops. It is suited to all corps commonly
grown in the area, including corn sugar beets,beans, alfalfa, small grain, potatoes, and
onions. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by
corn, corn for silage, sugar beets, small grain, or beans. Few conservation practices are
needed to maintain top yields.
Windbreaks and environmental plantings of trees and shrubs commonly grown in the area
are generally well suited to this soil. Cultivation to control competing vegetation should
be continued for as many years as possible following planting. Trees that are best suited
and have good survival are Rocky Mountain juniper, eastern redcedar, ponderosa pine,
Siberian elm, Russian-olive, and hackberry. The shrubs best suited are skunkbush sumac,
lilac, Siberian peashrub, and American plum.
Wildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture.
This soil has fair to poor potential for urban development. It has moderate to high shrink-
swell, low strength, and moderately slow pumeability. These features create problems in
dwelling and road
construction. Those areas that have loam or sandy loam in the lower part of the
substratum are suitable for septic tank absorption fields and foundations. Some areas of
this soil are adjacent to streams and are subject to occasional flooding. The potential is
fair for such recreational development as camp picnic areas and playgrounds. Capability
class I irrigated.
63 - Terry Fine Sandy Loam, 3-9%slopes
This is a moderately deep, well drained soil on plains at elevations of 4500 to 5000 feet.
It formed in residuum from sandstone. Included in mapping are small areas of soils that
have sandstone deeper than 40 inches. Also included are small areas of soils that have a
sandy clay loam and clay loam subsoil.
Typically the surface layer of this Terry soil is pale brown fine sandy loam about 6 inches
thick. The subsoil is pale brown fine sandy loam about 18 inches thick. The substratum is
fine sandy loam. Sandstone is at a depth of about 32 inches.
Permeability is moderately rapid. Available water capacity is moderate. The effective
rooting depth is 20 to 40 inches. Surface runoff is medium to rapid, and the erosion
hazard is moderate.
This soil is suited to limited cropping. Intensive cropping is hazardous because of
erosion. The cropping system should be limited to such close grown crops as alfalfa,
wheat, and barley. The soil is also suited to irrigated pasture. A suitable cropping system
is 3 to 4 years of alfalfa followed by 2 years of corn and small grain and alfalfa seeded
with a nurse crop.
Closely spaced contour ditches or sprinklers can be used in irrigating close grown crops.
Contour furrows or sprinklers should be used for new crops. Applications of nitrogen and
phosphorus help in maintaining good production.
The potential native vegetation on this range site is dominated by sand bluestem, sand
reedgrass, and blue grama. Needleandthread, swithgrass, sideoats grama, and western
wheatgrass are also prominent. Potential production ranges from 2200 pounds per acre in
favorable years to 1800 pounds in unfavorable years. As range condition deteriorates,the
sand bluestem, sand reedgrass, and switchgrass decrease and blue grama, sand dropseed,
and sand sage increase. Annual weeds and greases invade the site as range condition
becomes poorer.
Management of vegetation on this soil should be based on taking half and leaving half of
the total annual production. Seeding is desirable if the range is in poor condition. Sand
bluestem, sand reedgrass, switchgrass, sideoats grama,blue grama,pubescent
wheatgrass, and crested wheatgrass are suitable for seeding. The grass selected should
meet the seasonal - requirements of livestock. It can be seeded into a clean, firm
sorghum stubble, or it can be drilled into a firm prepared seedbed. Seeding early in spring
has proven most successful.
Windbreaks and environmental plantings are generally not suited to this soil. Onsite
investigation is needed to determine if plantings are feasible.
Wildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially, in areas of intensive agriculture. Rangeland wildlife, for example, the
pronghorn antelope, can be attracted by developing livestock watering facilities,
managing livestock grazing, and reseeding where needed.
The underlying sandstone is the most limiting feature of this soil. Neither septic tank
absorption fields nor sewage lagoons function properly. Site preparation for dwellings is
costly. Environmental and beautification plantings of trees and shrubs can be difficult to
establish. Potential is good, however, for such recreational development as camp and
picnic areas. Capability subclass IVe irrigated, VIe nonirrigated; Sandy Plains range site.
75- Vona Sandy Loam, 0-1 %slopes
This is a deep, well drained soil on high terraces at elevations of 4650 to 4950 feet. It
formed in alluvial deposits. Included in mapping are some leveled areas and small areas
of soils that have a loamy substratum.
Typically the surface layer of this Vona soil is grayish brown sandy loam about 10 inches
thick. The subsoil is brown fine sandy loam about 20 inches thick. The substratum to a
depth of 60 inches is sandy loam.
Permeability is moderately rapid. Available water capacity is moderate. The effective
rooting depth is 60 inches or more. Surface runoff is slow, and the erosion hazard is low.
This soil is used almost entirely for irrigated crops. It is suited to all corps commonly
grown in the area,including corn, sugar beets, beans, alfalfa, small grain, potatoes, and
onions. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by
corn, corn for silage, sugar beets, small grain, or beans. The rapidly permeable
substratum slightly restricts some crops.
All methods of irrigation are suitable,but furrow irrigations is the most common. Proper
irrigation management is essential. Barnyard manure and commercial fertilizer are
needed for top yields.
Windbreaks and environmental plantings are generally suited to this soil. Soil blowing,
the principal hazard in establishing trees and shrubs, can be controlled by cultivating only
in the tree row and by leaving a strip of vegetation between the row. Supplemental
irrigation may be necessary at the time of planting and during the dry periods. Trees that
are best suited and have good survival are Rocky Mountain juniper, eastern redcedar,
ponderosa pine Siberian elm, Russian-olive, and hackberry. The shrubs best suited are
skunkbush sumac, lilac, and Siberian peashrub.
Wildlife is an important secondary use of this soil. Ring-necked pheasant, mourning
dove, and many nongame species can be attracted by establishing areas for nesting and
escape cover. For pheasants, undisturbed nesting cover is essential and should be
included in plans for habitat development, especially in areas of intensive agriculture.
This soil has god potential for urban and recreational development. lawns, shrubs, and
trees grow well. The only limiting feature is the rapid permeability in the substratum,
which causes a hazard of ground water contamination from sewage lagoons. Capability
subclass Its irrigated.
76- Vona Sandy Loam, 1-3%slopes
This is a deep, well drained soil on plains and high terraces at elevations of 4600 to 5200
feet. It formed in eolian and alluvial deposits. Included in mapping are some leveled
areas. Also included are small areas of soils that have a loamy substratum and areas of
soils that are noncalcareous to a depth of 60 inches.
Typically the surface layer of this Vona soils is grayish brown sandy loam about 10
inches thick. The subsoil is brown fine sandy loam about 18 inches thick. The substratum
to a depth of 60 inches is sandy loam.
Permeability is moderately rapid. Available water capacity is moderate. The effective
rooting depth is 60 inches or more. Surface runoff is slow, and the erosion hazard is low.
In irrigated areas this soil is suited to all corps commonly grown in the area, including
corn, sugar beets,beans, alfalfa, small grain, and onions. An example of a suitable
cropping system is 3 to 4 years of alfalfa followed by corn, corn for silage, sugar beets,
small grain, or beans. Land leveling, ditch lining, and installing pipelines are needed for
proper water applications.
All methods of irrigation are suitable,but furrow irrigation is the most common.
Barnyard manure and commercial fertilizer are needed for top yields.
Windbreaks and environmental plantings are generally suited to this soil. Soil blowing,
the principal hazard in establishing trees and shrubs, can be controlled by cultivation only
in the tree row and by leaving a strip of vegetation between the rows. Supplemental
irrigation may be necessary at the time of planting and during dry periods. Trees that are
best suited and have good survival are Rocky Mountain juniper, eastern redcedar,
ponderosa, pine, Siberian elm, Russian-olive, and hackberry. The shrubs best suited are
skunkbush sumac, lilac, and Siberian peashrub.
Wildlife is an important secondary use of this soil. The cropland areas provide favorable
habitat for ring-necked pheasant and mourning dove. Many nongame species can be
attracted by establishing areas for nesting and escape cover. For pheasants, undisturbed
nesting cover is essential and should be included in plans for habitat development,
especially in areas of intensive agriculture. Rangeland wildlife, for example, the
pronghorn antelope, can be attracted by developing livestock watering facilities,
managing livestock grazing, and reseeding where needed.
This soil has good potential for urban and recreational development. lawns, shrubs, and
trees grow well. The only limiting feature is the rapid permeability in the substratum,
which causes a hazard of ground water contamination from sewage lagoons. Capability
subclass lie irrigated; We nonirrigated; Sandy Plains range site.
82- Wiley-Colby complex, 1-3%slopes
This nearly level map unit is on smooth plains in the western part of the survey area at
elevations of 4850 to 5000 feet. The Wiley soil makes up about 30 percent. About 10
percent is Heldt silty clay and Weld loam.
The Wiley soil is deep and well drained. It formed in calcareous eolian deposits.
Typically the surface layer is pale brown silt loam about 11 inches thick. The subsoil is
pale brown silty clay loam about 23 inches thick. The substratum to a depth of 60 inches
is very pale brown silty clay loam.
Permeability is moderately slow. Available water capacity is high. The effective rooting
depth is 60 inches or more. Surface runoff is medium, and the erosion hazard is moderate.
The Colby soil also is deep and well drained and formed in calcareous eolian deposits.
Typically the surface layer is pale brown loam about 7 inches thick. The underlying
material is very pale brown silt loam to a depth of 60 inches.
Permeability is moderate. Available water capacity is high. The effective rooting depth is
60 inches or more. Surface runoff is medium, and the erosion hazard is moderate.
This map unit is used for irrigated and nonirrigated cropland and for rangeland, wildlife
habitat, and urban development.
In irrigated areas these soils are suited to all crops commonly grown in the area, including
corn, sugar beets, beans, alfalfa, small grain, and onions. An example of a suitable
cropping system is 3 to 4 years of alfalfa followed by corn, corn for silage, sugar beets,
small grain, or beans. Land leveling, ditch lining and installing pipelines may be needed
for proper water applications.
All methods of irrigation are suitable but furrow irrigation is the most common. Barnyard
manure and commercial fertilizer are needed for top yields.
In nonirrigated areas these soils are suited to winter wheat, barley, and sorghum. Most of
the acreage is planted to winter wheat. The predicted average yield is 28 bushels per acre.
The soil is summer fallowed
in alternated years to allow moisture accumulation. Generally precipitation is too low for
beneficial use of fertilizer.
Stubble mulch farming, striperopping, and minimum tillage are needed to control soil
blowing and water erosion. Terracing also may be needed to control water erosion.
The potential native vegetation is dominated by blue grama. Several mid grasses such as
western wheatgrass and needleandthread are also present. Potential production ranges
from 1600 pounds per acre in favorable years to 1000 pounds in unfavorable years. As
range condition deteriorates, the mid grasses decrease; blue grama,buffalograss,
snakeweed, yucca, and fringed sage increase; and forage production drops. Undesirable
weeds and annuals invade the site as range condition becomes poorer.
Management of vegetation on this soil should be based on taking half and leaving half of
the total annual production. Seeding is desirable if the range is in poor condition. Sideoats
grama, little bluestem, western wheatgrass, blue grama, pubescent wheatgrass, and
crested wheatgrass are suitable for seeding. The grass selected should meet the seasonal
requirements of livestock. It can be seeded into a clean, firm sorghum stubble or it can be
drilled into a firm prepared seedbed. Seeding early in spring has proven most successful.
Windbreaks and environmental plantings are generally well suited to these soils.
Cultivation to control competing vegetation should be continued for as many years as
possible following planting. Trees that are best suited and have good survival are Rocky
Mountain juniper, eastern redcedar,ponderosa pine, Siberian elm, Russian-olive, and
hackberry. The shrubs best suited are skunkbush sumac, lilac, Siberian peashrub, and
American plum.
Openland wildlife, such as pheasant, mourning dove, and cottontail are best suited to
these soils. Wildlife habitat development, including tree and shrub plantings and grass
plantings to serve as nesting areas, should be successful without irrigation during most
years. Under irrigation, good wildlife habitat can be established, benefiting many kinds of
openland wildlife.
The Wiley soil has only fair potential for urban and recreational development. Slow
permeability, moderate shrink-swell potential, and limited bearing capacity cause
problems in dwelling and road construction. The Colby soil has good potential for urban
and recreation development.
Road design can be modified to compensate for the limited capacity of this soil to support
a load. Capability subclass Ile irrigated, IVe nonirrigated; Loamy Plains range site.
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GEOTECHNICAL SLOPE STABILITY ANALYSIS
FORT LUPTON PIT
Prepared For.
LaFarge NA
1400 W. 64th Ave
Denver, CO
Prepared By:
Weiland, Inc.
10395 W. Colfax, Suite 350
Lakewood, CO
303-436-0951
September, 2004
Weiland Inc.
Environmental& Engineering
1.0 SLOPE STABILITY ANALYSIS
A slope stability analysis was performed for 21 separate proposed gravel pits.
The purpose of the analysis is to evaluate safe setback distances for pit
excavations from permanent man-made structures and hydrologic features.
1.1.METHODOLOGY
The digital model SB-Slope developed by Von Gunten Engineering Software, Inc.
was used to predict a safety factor for a given pit wall configuration. Soils layers
for a given pit cell were entered into Autodesk Land Desktop Development 3 and
point files for line geometry were extracted to text files. Phreatic surfaces were
predicted utilizing the Theis solution for 100 ft distance from the pit dewatering
trench and the Dupuit-Forchheimer approximation was used to predict the
drawdown curve closer than 100ft from the dewatering trench. Phreatic surfaces
near streams were approximated based on a typical stream recharge cross
section.
1.2.DATA INPUT
Model input consisted of soil layer geometry described above and soil physical
strength parameters. Soil strength parameters were taken from a memo from
Alan Sorenson of the Division of Minerals and Geology and Design of Small
Dams. The soils input data are summarized in table 1. Graphical and numeric
input data is given in Appendix I for each mining Phase and Cell.
Table 1 — SOILS DATA
Stratigraphic Layer Density Cohesion (psf) Phi (+)
(pcf)
Silt and Clay—ML 90 4 34
(moist)
Gravel (moist) GW- 130 0 35'
unsat.
Gravel (saturated). 137 0 35
GW-sat.
Weathered Claystone 142 0 14
(saturated)
Intact Claystone (dry) 150 500 25
1.3.MODEL OUTPUT
The model output failures and safety factor are given in Appendix I for each
mining phase and cell. Table 2 summarized the recommended setback for each
mining phase and cell.
Table 2- Recommended Setbacks
RECOMMENDED RECOMMENDED
SETBACK FROM SETBACK FROM REFERENCE
PHASE CELL STRUCTURES STREAMS FIGURE(S)
[Fri
PHASE 1 CELL 1 57 75 1
CELL 2 57 75 2
PHASE 2 CELL 1 63 83 3,4
CELL 2 62 83 5,4
PHASE 3 CELL 1 36 75 6
6
PHASE 4 CELL 1 43 75 7,8
PHASE 5 CELL 1 31 38 9,10
CELL 2 31 38 9,10
CELL 3 65 80 11,27
CELL 4 60 81 12,13
NA -Constrained by Gas
CELL 5 56 Line 14,15
PHASE 6 CELL 1 38 56 16,17
CELL 2 38 56 16,17
PHASE 7 CELL 1 38 50 18,19
CELL 2 51 NA 20
PHASE 8 CELL 1 51 NA 21
PHASE 9 CELL 1 50 NA 22
PHASE 10 CELL 1 44 75 23,24
CELL 2 52 71 25,26
CELL 3 52 71 25,26
PLANT AREA CELL 1 52 71 25,26
1.4.DISCUSSION
In some cases cell depth and soil types were similar enough to allow setbacks to
be determined from the determination of another cell. For example, the depth
and soil types of cell 2 and cell 3 of phase 10 were similar and therefore setback
recommendations for cell 2 are based on analysis for cell 3.
Overall, recommended setbacks are consistent with values used for other pits
previously analyzed by Weiland, Inc with similar soils and depth. Recommended
setback distances from streams could be tightened with better phreatic surface
data, however these analyses are based on conservative estimations and would
therefore satisfy regulators.
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