HomeMy WebLinkAbout20060514.tiff U.S.D.A. Soil Survey of Weld County,Colorado
Southern Part, Sheet Number 8
Applicable Soil Narrative: 32
Narrative described on the following page.
Soil Survey of Weld County, Colorado excerpt(Southern Portion)
Published by the United States Department of Agriculture Soil Conservation Service
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2006-0514
Soil Classification#32: Kim loam, 1 to 3 percent slopes
This is a deep,well drained soil on smooth plains and alluvial fans at elevations of 4,900 to 5,250 feet. It
formed in mixed eolian deposit 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 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
or 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
(fig.6),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 wheat and is summer(allowed 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 1,600 pounds per acre in
favorable years to 1,000 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, 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 the limited capacity of this soil to support a load. Septic tank absorption
fields function property,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 Ile irrigated, IVe nonirrigated; Loamy Plains range site.
-
Ammi
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
RIDGEVIEW FARMS PUD
SOUTHWEST CORNER OF WELD COUNTY ROAD 35
AND STATE HIGHWAY 392
WELD COUNTY, COLORADO
TERRACON PROJECT NO. 21055015
August 24, 2005
—
Prepared for
Casseday Creative Designs, LLC
826 9t Street, Suite B-100
Greeley, Colorado 80631
Prepared by:
Terracon
1289 First Avenue
Greeley, Colorado 80631
Telephone (970) 351-0460
Fax (970) 353-8639
lierracon
lierracon
Consulting Engineers&Scientists
August 24, 2005 1289 First Avenue
Post Office Box 1744
Greeley,Colorado 80632-1744
.. Casseday Creative Designs, LLC Phone 970.351.0460
Fax 970.353.8639
826 9th Street, Suite B-100 www.terracon.com
Greeley, Colorado 80631
Attn: Mr. Robb Casseday
._ Re: Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
.. Southwest Corner of Weld County Road 35 and State Highway 392
Weld County, Colorado
Terracon Project No. 21055015
Terracon has completed a preliminary geotechnical engineering exploration for the proposed PUD to
.. be located at the southwest corner of Weld County Road 35 and State Highway 392 in Weld County,
Colorado. This study was performed in general accordance with our proposal number P2105023g
dated March 17, 2005.
The results of our preliminary engineering study, including the boring location diagram, laboratory test
results, test boring records, and the preliminary geotechnical assessment of suitable foundation
systems and other earth connected phases of this project are attached.
We appreciate being of service to you in the preliminary geotechnical engineering phase of this
project, and are prepared to assist you during the construction phases as well. If you have any
questions concerning this report or any of our testing, inspection, design and consulting services,
please do not hesitate to contact us.
`Utwutnnryry
Sincerely, ,.`gyp.. REG/ST��•\
�O. •pLEX4 '•Fy�'ys
TERRACON 45).co..� • -•e? o
L___,36512
.. 6„„,p,,,2.; y LL '4 '
Andrei Bedoya, E.I. Ty G. Alexander, P.E.
, NALEC1,e
Staff Engineer Office Manager/Geotechnical Engineer
r, Copies to: Addressee (3)
Delivering Success for Clients and Employees Since 1965
More Than 60 Offices Nationwide
TABLE OF CONTENTS
Page No.
Letter of Transmittal
INTRODUCTION 1
PROPOSED CONSTRUCTION 1
SITE EXPLORATION 2
Field Exploration 2
Laboratory Testing 2
SITE CONDITIONS 3
Soil and Bedrock Conditions 7
Field and Laboratory Test Results 7
Groundwater Conditions 8
PRELIMINARY ENGINEERING ANALYSES AND RECOMMENDATIONS 8
Geotechnical Considerations 8
Foundation Systems 9
Basement Construction 9
Preliminary Pavement Section Design, Construction, and Maintenance 9
Septic System Construction 12
Earthwork 12
General Considerations 12
Site Preparation 12
Fill Materials and Placement 13
Excavation and Trench Construction 14
Additional Design and Construction Considerations 14
Underground Utility Systems 14
GENERAL COMMENTS 15
APPENDIX A
Boring Location Plan
Logs of Borings
APPENDIX B
Laboratory Test Results
APPENDIX C
General Notes
General Notes — Sedimentary Bedrock Classification
Unified Soil Classification
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
RIDGEVIEW FARMS PUD
SOUTHWEST CORNER OF WELD COUNTY ROAD 35
AND STATE HIGHWAY 392
WELD COUNTY, COLORADO
TERRACON PROJECT NO. 21055015
AUGUST 24, 2005
INTRODUCTION
This report contains the results of our preliminary geotechnical engineering exploration for the
proposed PUD to be located at the southwest corner of Weld County Road 35 and State Highway 392
in Weld County, Colorado.
The purpose of these services is to provide information and a preliminary geotechnical engineering
assessment relative to:
r • subsurface soil and bedrock conditions
• groundwater conditions
• preliminary foundation design
• suitability for basement construction
• pavement design and construction
• suitability for standard septic systems
• earthwork
The information contained in this report is based upon the results of field and laboratory testing,
preliminary engineering analyses, and experience with similar soil conditions, structures and our
understanding of the proposed project.
PROPOSED CONSTRUCTION
_ Terracon understands the site consists of 63 acres of land that will be developed with a 24 lot single
family residential subdivision. Each residence will be supported by an individual septic system on each
lot. Additional infrastructure at the site will include construction of site utilities, curb, gutter, and roads.
Site grading plans were not available, however Terracon assumes site grading cuts and fills will not
exceed 3 feet.
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
SITE EXPLORATION
The scope of the services performed for this project included a site reconnaissance by a Terracon
representative, a subsurface exploration program, laboratory testing and preliminary engineering
assessment.
Field Exploration
Five test borings were drilled on August 4, 2005. The borings were drilled to approximate depths of 20
feet at the locations shown on the Boring Location Diagram, Appendix A. Five percolation test holes
were drilled adjacent to the location of each of the test borings. Percolation tests were conducted in
general accordance with Weld County requirements. All borings were advanced with a truck-mounted
drilling rig utilizing 4 and 6-inch diameter solid stem augers.
The borings were located in the field by measurements from property lines and existing site features.
Ground surface elevations at each boring location were estimated from a site topographic map
provided by the client. The accuracy of boring locations and elevations should only be assumed to the
— level implied by the methods used to determine each.
Lithologic logs of each boring were recorded by the field representative during the drilling operations.
At selected intervals, samples of the subsurface materials were taken by driving split-spoon and ring-
barrel samplers.
Penetration resistance measurements were obtained by driving the split-spoon and ring-barrel
samplers into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration
resistance value is a useful index in estimating the consistency, relative density or hardness of the
materials encountered.
Groundwater conditions were evaluated in each boring at the time of site exploration, and 2 to 5 days
— after completion of drilling.
Laboratory Testing
All samples retrieved during the field exploration were returned to the laboratory for observation by the
_ project geotechnical engineer and were classified in accordance with the Unified Soil Classification
System described in Appendix C. Samples of bedrock were classified in accordance with the general
notes for Bedrock Classification. At that time, the field descriptions were confirmed or modified as
_ necessary and an applicable laboratory testing program was formulated to determine engineering
properties of the subsurface materials. Boring logs were prepared and are presented in Appendix A.
2
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
Laboratory tests were conducted on selected soil and bedrock samples and are presented on the
boring logs and in Appendix B. The test results were used for the preliminary geotechnical
engineering assessment. All laboratory tests were performed in general accordance with the
applicable local or other accepted standards.
Selected soil and bedrock samples were tested for the following engineering properties:
• Water Content
• Dry Density
• Consolidation/Expansion
• Grain Size
• Plasticity Index
SITE CONDITIONS
Geology
General Information
The site consists of a 63 acre tract located south of Colorado Highway 392 northwest of Greeley
and west of Lucerne, Colorado. More particularly the site is described as a tract of land situate in the
Northeast 'A of Section 23, Township 6 North, Range 66 West of the 6th P.M. The site consists of
irrigated farm land which slopes gently to the south and west. The Seeley Lake Inlet Ditch forms the
_ west property line. The ditch is 15 to 20 feet deep and approximately 50 feet wide. The Greeley No
2 Canal froms the northeast boundary. The Greeley No 2 canal has approximate 1:1 grass covered
slopes. Portions of the slopes are protected by broken concrete rip rap. A ditch rider's road is
located along the south side of the ditch. The ditch is approximately 5 feet deep and 30 feet wide. A
gas compressor station is located in the northeast corner of the property. The site is bordered on
the east by WCR 35 and on the south by farmland and residences. A Farm house and outbuildings
are located northeast of the Greeley No 2 Canal. An oil or gas storage tank and compressors are
located adjacent to the south property line, which is fenced. The Seeley Lake inlet ditch has varying
slopes of 1:1, 2:1 to near vertical in places. Trees, brush, and grasses line the banks of the inlet.
Logs and branches along with plastic and other debris have been used to stabilize the steeper
banks of the inlet ditch. A concrete structure is located at the northwest corner of the property where
the ditch enters the site. This structure has been undermined by erosion approximately 5 feet. The
site slopes gently to the southwest and has positive drainage toward Seeley Lake which is located
^ south of the site. Maximum relief of the site is approximately 20 feet.
3
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
The Topography at the site varies from approximate elevation 4755 at the northeast corner of the
site to approximate elevation 4735 at the southwest corner of the property. The Drainage in the area
is to the southeast toward Seeley Lake inlet Ditch. The majority of the runoff at the site is channeled
through the inlet ditch along the west edge of the property.
The visual observation of the site was performed by Neil R. Sherrod, PG on March 18, 2005. The
report was prepared by Mr. Sherrod. A Preliminary Geotechnical Engineering Report, which
includes the project area, was prepared by Terracon, September 26, 1996 (Project No. 20965136).
Exposures of shale and sandstone were noted in the banks of the Seeley Lake Inlet Ditch
approximately 5 to 10 feet below the top of the slope. The bedrock is thin bedded weathered and
appears to be relatively flat lying. Pertinent geologic literature and the subsurface data obtained
during a previous field investigation were reviewed. This data along with the geologist's general
knowledge and experience of the area was used to determine the geologic characteristics of the
site.
Geologic Descriptions
The subject site is located within the Colorado Piedmont section of the Great Plains physiographic
province east of the Front Range of the Rocky Mountain physiographic province. The Colorado
Piedmont, formed during Late Tertiary and Early Quaternary Periods (approximately two million
years ago), is a broad, erosional trench which separated the Southern Rocky Mountains from the
High Plains. Structurally, the site lies on the western flank of the Denver Basin. During the Late
Mesozoic and Early Cenozoic Periods (approximately 70 million years ago), intense tectonic activity
occurred, causing the uplifting of the Front Range and associated downwarping of the Denver Basin
'- to the east. Relatively flat uplands and broad valleys characterize the present-day topography of the
Colorado Piedmont in this region.
The site is underlain by the Cretaceous Laramie Formation (Sheldon, D.C. and Rodgers, W.P.,
Bedrock Geology Windsor Study Area, Larimer and Weld Counties, Colorado, Colorado Geological
Survey, 1975). The Laramie Formation consists of shale, claystone, sandstone and coal beds. The
bedrock consisting of interbedded sandstones, siltstones, and claystone was encountered in borings
2 and 4, drilled in conjunction with this report prepared by Terracon in September of 1996, at depths
if 12 %2 to 14 1/2 feet below the surface The bedrock generally has a weathered zone of 3 to 4 feet.
The Laramie formation is overlain by eolian deposits of Pleistocene or Recent age. According to
(Hart, Stephen S., 1974 Potentially Swelling Soil and Rock in the Front Range Urban Corridor,
Colorado, Colorado Geological Survey, Environmental Geology No. 7). These deposits consist of
windblown sand or silt. The material in general has low swell potential and may be subject to severe
4
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
settlement or hydrocompaction. USDA Soil conservation Service maps (U.S. Department of
Agriculture, Soil Conservation Service, Soil Survey of Weld County, Colorado, 1980) indicate the
soils at the site consist of Kim Loam and Olney Fine Sandy Loam. The soils encountered in the five
test borings drilled at the site consist of lean clay, silty sand, or clayey sand. A description of the
upper subsoils and the bedrock encountered is included in the Log of Boring included in Appendix of
this report. Surface bedrock outcrops were observed along the slopes of the Seeley Lake Inlet
Ditch. The bedrock is moderately weathered and jointed. The shale is thin bedded and the soft
friable sandstone below erodes relatively easily forming flatter slopes.
According to Widmann, B.L., Kirkham, R.M. and Rogers, W.P, in their publication (Preliminary
Quaternary Fault and Fold Map and Database of Colorado, Colorado Geological Survey, Open File
Report 98-8, 1998) there are no potentially active faults in or adjacent to the project area. Therefore
seismic activity I the area is anticipated to be low and from a structural standpoint the property
should be relatively stable.
The site lies within the drainage basin of the Cache La Poudre River but does not lie within the
topographic flood plain of the stream. The drainage of the area is directed toward the Seeley Lake
Inlet Ditch, Seeley Lake and the Cache La Poudre River. The major drainage at the site follows the
Seeley Lake Inlet Canal. The inlet is deep and has varying slopes. Portions of the slopes are steep
and heavily eroded.
Ground water was encountered in the two borings drilled at the site, in September of 1996 at depths
of 512 to 151/2 feet. Water levels are subject to change due to seasonal variations and irrigation
demands on and adjacent to the property. In addition a perched water table may develop on top of
the bedrock stratum. In this case water may percolate though the upper subsoils and become
trapped on the relatively impervious bedrock. The publications [Hiller, Donald, E., And Schneider,
Paul, A Jr., Depth to the Water Table (1976-77) in the Boulder-Fort Collins-Greeley Area, Front
Range Urban Corridor Colorado, U. S. Geological Survey, Miscellaneous Investigations Series Map
1-855-1, 1979] indicates the majority of the site consists of area where localized water table aquifers
occur in colluvial, landside and windblown deposits and in consolidated sedimentary rocks. The
depth to the water table generally ranges from 5 to 20 feet.
Based on the field observation of the site and review of geologic data, it is our opinion; from a
geologic standpoint the site is relatively stable and suitable for construction of the proposed
residences. Due to the gentle slopes, except along the walls of the Seeley Lake Inlet Ditch, of 1 to 1
%2 percent at the site, geologic hazards do to mass movement caused by gravity, such as
landslides, mudflows, etc., are anticipated to be low. Due to the sandy nature of the subsoils at the
-- site some soil erosion can be anticipated. With proper site grading and drainage designed for the
5
— Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
proposed residences and street along with revegetation of stripped areas, erosional problems at the
site should be minimal. The existing inlet ditch that flows along the west side of the site should be
maintained to allow for anticipated flows from the property to the north.
Mineral Resources
The subject property is located in a producing oil and gas field. A Producing well owned by Bonanza
Creek Oil Company is located directly to the south on the adjacent property.
This well is part of the Watterberg oil and Gas Field which contains a large number of producing
wells (Colorado Geological Survey, Lawson and Hemborg, Oil and Gas Fields of Colorado
Statistical Summary though 1996, 1999)
The Laramie Formation contains economic coal deposits adjacent to the project area and cola has
been extensively mined in the past in the Boulder Weld Coalfield south of the project area. However
a review of several maps and data bases indicates there are no coal deposits below the site. The
map prepared by Jones, David, C, Schultz Janet, E. and Murray, Keith, D. (Coal Resources and
Development Map of Colorado, Colorado Geological Survey, Series 9, 1978) indicate coal deposits
exist several miles to the northeast of the property. These deposits consist of sub bituminous to
bituminous coal beds between 150 to 3000 feet below the surface. The Energy Resources Map of
Colorado (1977) published by the US Geological Survey and the Colorado Geological Survey
indicated coal beds exist approximately 3 miles north of the project area. These beds are described
as being within 300 feet of surface.
According to the publication (Location Map and Descriptions of Metal Occurrences in Colorado with
Notes on Economic Potential, Colorado Geological Survey, Map Series 28, 1994) by Streufert,
Randall K. and Cappa, James, A., there are no deposits of economic metals on or in the vicinity of
the project area. The publication (Sand, Gravel, and Quarry Aggregate Resources Colorado Front
Range Counties, Colorado Geological Survey, Special Publication 5-A, 1974) by Schwochow, S.D.,
Shroba, R., R., and Wicklein, P., C., indicates there are no aggregate resources on the property. No
sand and gravel was encountered in the two test boring drilled at the site.
Geologic site characteristics
The site is to be developed into 24 1 1/2 to 2 1/4 acre residential lots. Location of proposed residences
on these lots at the site should be carefully planned to accommodate the existing oil and gas
producing facilities. Construction should not be considered adjacent to wells or over existing
underground pipelines. Old fill may be encountered at the site. These areas should be avoided or
^ excavated to natural soils and properly backfilled. Drainage though the site should be properly
6
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
maintained and directed to the south and west toward Seeley Lake Inlet Ditch. The slopes of the
inlet ditch should be regarded to provide a relatively uniform slope of 2:1 or flatter. Surface drainage
should be directed into the large inlet ditch along the west edge of the property wherever possible.
Construction should be kept a minimum of 50 to 75 feet back from the top edge of the Seeley Lake
Inlet Ditch. Where possible the slope of the inlet ditch should be regarded to a minimum grade of
2:1. All debris should be removed from the ditch slopes and the slopes should be vegetated with
native grasses. Rip rap should be placed in the lower portion of the inlet ditch to minimize erosion
due to the flow of water though the ditch. Dewatering systems may be required around structures
place adjacent to the Greeley No 2 Canal to intercept possible seepage from the ditch.
SUBSURFACE CONDITIONS
Soil and Bedrock Conditions
As presented on the Logs of Borings, surface soils to depths of 7 to 16 feet consisted of inter-bedded
clay and sand soils consisting silty sand, clayey sand, lean clay with sand, and sandy lean clay. The
materials underlying the surface soils and extending to the maximum depth of exploration consisted of
sedimentary bedrock composed of claystone, siltstone, and sandstone.
Field and Laboratory Test Results
Field test results indicate that the clay soils vary from medium stiff to very stiff in consistency. The
sand soils vary from loose to medium dense in relative density. The underlying bedrock varies from
weathered to very hard in hardness.
Laboratory test results indicate that the subsurface materials encountered exhibit compression and
expansion potentials ranging from about -0.4% (compression) to 0.3% (expansion) for clayey sand
and lean clay soils, accordingly. The compression and expansion potentials outlined above were
obtained by inundating confined samples under a surcharge load of 500 psf(pounds per square foot).
The expansion potential outlined above is considered to be low according to CAGE (Colorado
Association of Geotechnical Engineers) guidelines.
Laboratory test results also indicate that the lean clay and clayey sand materials encountered have
Plasticity Indices ranging from 15 to 23.
7
-
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
Percolation Test Results
Percolation testing conducted in the area of the proposed soil absorption bed are summarized as
— follows:
{ I:r.;r �J t t 3+�i 4 �4 4 t E�Iib
• . Percotattor e t Results
1
r . It I. ,,,,;:E, u, .3,
Test Hole Depthti gnlrt" Perco ati'on l �e
{ iri hpps}„t,{ Cladsificatrbnt 4#a� r m�nc tes/mc ikt•
"
��M�-HAaAG Ii4nU I I` 4 t N{Iti.l. Iai{t4I(Gt�kw.t u.•�
1 30 CL 19
2 30 CL 27
3 30 CL 120
4 30 SC 49
5 30 SC 23
Field test results indicate that standard septic systems should feasible for construction on the site at
locations where percolation rates are between 5 minutes per inch and 60 minutes per inch as outlined
in Weld County regulations. Where percolation rates exceed these values, engineered septic system
may be necessary. A complete percolation test will be necessary for each lot to determine the
suitability of individual lots for standard septic system construction.
Groundwater Conditions
Groundwater was encountered at approximate depths of 8 to 17 feet in the test borings at the time of
field exploration. When checked 2 to 5 days after the drilling, groundwater was measured at
approximate depths of 51/2 to 15% feet. These observations represent groundwater conditions at the
time of the field exploration, and may not be indicative of other times, or at other locations.
Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions.
PRELIMINARY ENGINEERING ANALYSES AND RECOMMENDATIONS
Geotechnical Considerations
Based on the preliminary geotechnical engineering analyses, subsurface exploration and laboratory
test results, it is our opinion that spread footing foundation systems should be suitable for support of
proposed residences to be constructed at the site. Slab on grade also appears suitable for the interior
floor systems provided that care is taken in the placement and compaction of the subgrade soil. On-
site soils should be suitable for use as engineered fill beneath the foundation systems and floor slabs.
8
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
Preliminary design and construction recommendations for foundation systems and other earth
connected phases of the project are outlined below.
Foundation Systems
Due to the properties of the on-site soils it appears that spread footing foundation systems should be
suitable for support of proposed residences to be constructed at the site. The on-site materials exhibit
strength characteristics that indicate possible net allowable bearing pressures ranging from 1,000 to
3,000 psf (pounds per square foot), however, these should not be used as final design values.
Minimum dead load pressures could be required if more expansive soils are encountered at the site.
Site or structure specific subsurface investigations should be conducted in the future to determine the
existing subsurface conditions and design criteria for each specific structure.
Basement Construction
Groundwater was encountered on the site at depths of 51/2 to 151/2 feet below existing grade. Full-
depth basement construction is considered feasible on the site provided that basement subgrade is a
_ ..y minimum of 3 feet above groundwater level. Site grades could be elevated in areas where
groundwater was encountered at relatively shallow depths to allow for full-depth basement
construction.
Preliminary Pavement Section Design, Construction, and Maintenance
Preliminary Pavement Section Design
Preliminary design of pavements for the project have been based on the procedures outlined in the
1993 Guideline for Design of Pavement Structures by the American Association of State Highway and
Transportation Officials (AASHTO) as well as Colorado Department of Transportation (CDOT) design
procedures.
Traffic patterns and anticipated loading conditions were not available. However, we anticipate that
traffic loads could be produced primarily by automobile traffic and occasional delivery and trash
removal trucks. Accordingly, an 18-kip Equivalent Single Axle Load (ESAL) of 73,000 was utilized for
preliminary design. If heavier traffic loading is expected, this office should be provided with the
information and allowed to review these pavement sections.
Local drainage characteristics of proposed pavements areas are considered to vary from fair to good
depending upon location on the site. For purposes of this design analysis, fair drainage characteristics
are considered to control the design. These characteristics, coupled with the approximate duration of
9
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
saturated subgrade conditions, results in a design drainage coefficient of 1.0 when applying the
AASHTO criteria for design.
For flexible pavement design, a terminal serviceability index of 2.0 was utilized along with an inherent
reliability of 85% and a design life of 20 years. Using the correlated design R-value of 10, appropriate
ESAL, environmental criteria and other factors, the structural number (SN) of the pavement section
was determined on the basis of the 1993 AASHTO design equation.
The required total thickness for the pavement structure is dependent primarily upon the foundation soil
or subgrade and upon traffic conditions. Based on the soil conditions encountered at the site and the
anticipated type and volume of traffic as the criterion for preliminary pavement design, the following
minimum pavement thickness is recommended:
Recommended Pavement Thickness(Inches)
Traffic Area Asphalt Concrete Aggregate Base Total
Surface Course
Local Streets 3% 6 9%
Pavement Section Construction
Pavement design methods are intended to provide structural sections with adequate thickness over
a particular subgrade such that wheel loads are reduced to a level the subgrade can support. The
support characteristics of the subgrade for pavement design do not account for shrink/swell
movements of an expansive clay subgrade such as the soils encountered on this project. Thus, the
pavement may be adequate from a structural standpoint, yet still experience cracking and
deformation due to shrink/swell related movement of the subgrade. It is, therefore, important to
minimize moisture changes in the subgrade to reduce shrink/swell movements.
Site grading is generally accomplished early in the construction phase. However as construction
proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation,
or rainfall. As a result, the pavement subgrade may not be suitable for pavement construction and
corrective action will be required. The subgrade should be carefully evaluated at the time of
pavement construction for signs of disturbance or excessive rutting. Further, we recommend the
pavement areas be rough graded and then thoroughly proofrolled with a loaded tandem axle dump
truck prior to final grading and paving. Particular attention should be paid to high traffic areas that
were rutted and disturbed earlier and to areas where backfilled trenches are located. If disturbance
has occurred or unstable subgrade soils are observed, pavement subgrade areas should be
reworked, moisture conditioned, or removed and replaced with properly compacted engineered fill to
10
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
the recommendations in this report immediately prior to paving. All pavement areas should be
moisture conditioned and properly compacted to the recommendations in this report immediately
prior to paving.
Aggregate base course should consist of a blend of sand and gravel which meets specifications for
quality and gradation. Use of materials meeting Colorado Department of Transportation (CDOT)
Class 5 or 6 specifications is recommended for base course. Aggregate base course should be
placed in lifts not exceeding six inches and should be compacted to a minimum of 95% Standard
Proctor Density (ASTM D698).
Asphalt concrete should be composed of a mixture of aggregate, filler and additives, if required, and
approved bituminous material. The asphalt concrete should conform to approved mix designs stating
the Marshall or Superpave properties, optimum asphalt content, job mix formula and recommended
mixing and placing temperatures. Aggregate used in asphalt concrete should meet particular
gradations. Material meeting Colorado Department of Transportation Grading S or SX specification is
recommended for asphalt concrete. Mix designs should be submitted prior to construction to verify
their adequacy. Asphalt material should be placed in maximum 3-inch lifts and should be compacted
to within a range of 92% to 96% of maximum theoretical specific gravity.
Pavement Preventative Maintenance
Long term pavement performance will be dependent upon several factors, including maintaining
subgrade moisture levels and providing for preventive maintenance. The following
recommendations should be considered the minimum:
• Site grading at a minimum 2% grade away from the pavements;
• The subgrade and the pavement surface have a minimum '/ inch per foot slope to promote proper
surface drainage.
• Consider appropriate edge drainage and pavement under drain systems,
• Install pavement drainage surrounding areas anticipated for frequent wetting (e.g. garden centers,
wash racks)
• Install joint sealant and seal cracks immediately,
• Seal all landscaped areas in, or adjacent to pavements to minimize or prevent moisture
migration to subgrade soils;
• Placing compacted, low permeability backfill against the exterior side of curb and gutter; and,
11
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
• Placing curb, gutter and/or sidewalk directly on subgrade soils without the use of base course
materials.
Preventive maintenance should be planned and provided for through an on-going pavement
management program. Preventive maintenance activities are intended to slow the rate of pavement
deterioration, and to preserve the pavement investment. Preventive maintenance consists of both
localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g.
surface sealing). Preventive maintenance is usually the first priority when implementing a planned
pavement maintenance program and provides the highest return on investment for pavements.
Prior to implementing any maintenance, additional engineering observation is recommended to
determine the type and extent of preventive maintenance.
Septic System Construction
Field test results indicate that standard septic systems should feasible for construction on the site at
locations where percolation rates are between 5 minutes per inch and 60 minutes per inch as outlined
in Weld County regulations. Where percolation rates exceed these values, engineered septic system
may be necessary. A complete percolation test will be necessary for each lot to determine the
suitability of individual lots for standard septic system construction.
Earthwork
General Considerations
The following presents recommendations for site preparation, excavation, subgrade preparation and
placement of engineered fills on the project.
All earthwork on the project should be observed and evaluated by Terracon. The evaluation of
earthwork should include observation and testing of engineered fill, subgrade preparation, foundation
bearing soils, and other geotechnical conditions exposed during the construction of the project.
Site Preparation
Strip and remove existing vegetation, debris, and other deleterious materials from proposed building
and pavement areas. All exposed surfaces should be free of mounds and depressions which could
prevent uniform compaction.
12
-- Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
Subgrade soils beneath proposed pavements, as well as all exposed areas which will receive fill, once
properly cleared where necessary, should be scarified to a minimum depth of 8 inches, conditioned to
near optimum moisture content, and compacted.
Although evidence of fills or underground facilities such as septic tanks, cesspools, basements, and
utilities was not observed during the site reconnaissance, such features could be encountered during
construction. If unexpected fills or underground facilities are encountered, such features should be
removed and the excavation thoroughly cleaned prior to backfill placement and/or construction.
It is anticipated that excavations for the proposed construction can be accomplished with conventional
earthmoving equipment.
Depending upon depth of excavation and seasonal conditions, groundwater may be encountered in
excavations on the site. Pumping from sumps may be utilized to control water within excavations.
Based upon the subsurface conditions determined from the geotechnical exploration, subgrade soils
exposed during construction are anticipated to be relatively stable. However, the stability of the
subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unstable
conditions develop, workability may be improved by scarifying and drying. Overexcavation of wet
zones and replacement with granular materials may be necessary.
The individual contractor(s) is responsible for designing and constructing stable, temporary
excavations as required to maintain stability of both the excavation sides and bottom. All excavations
should be sloped or shored in the interest of safety following local, and federal regulations, including
current OSHA excavation and trench safety standards.
Fill Materials and Placement
Clean on-site soils or approved imported materials may be used as fill material.
Imported soils (if required) should conform to the following:
Percent fines by weight
Gradation fASTM C136)
3" 100
No. 4 Sieve 70-100
No. 200 Sieve 50 (max)
• Liquid Limit 30 (max)
13
a Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
• Plasticity Index 15 (max)
Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures
that will produce recommended moisture contents and densities throughout the lift. For fills not
exceeding 6 feet in depth, recommended compaction criteria for engineered fill materials is 95% of
maximum dry density as determined by ASTM D698.
On-site clay soils should be compacted within a water content range of 2 percent below to 2 percent
_ above optimum. On-site and imported sand soils should be compacted within a water content range
of 4 percent below to 2 percent above optimum unless modified by the project geotechnical engineer.
Excavation and Trench Construction
Excavations into the on-site soils will encounter a variety of conditions, including caving soils and
possibly groundwater. The individual contractor(s) should be made responsible for designing and
constructing stable, temporary excavations as required to maintain stability of both the excavation
sides and bottom. All excavations should be sloped or shored in the interest of safety following local,
— -- and federal regulations, including current OSHA excavation and trench safety standards.
The soils to be penetrated by the proposed excavations may vary significantly across the site. The
preliminary soil classifications are based solely on the materials encountered in widely spaced
exploratory test borings. The contractor should verify that similar conditions exist throughout the
proposed area of excavation. If different subsurface conditions are encountered at the time of
construction, the actual conditions should be evaluated to determine any excavation modifications
necessary to maintain safe conditions.
As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral
distance from the crest of the slope equal to no less than the slope height. The exposed slope face
should be protected against the elements.
Additional Design and Construction Considerations
Underground Utility Systems
All piping should be adequately bedded for proper load distribution. It is suggested that clean, graded
gravel compacted to 75 percent of Relative Density ASTM D4253 be used as bedding. Where utilities
are excavated below groundwater, temporary dewatering will be required during excavation, pipe
placement and backfilling operations for proper construction. Utility trenches should be excavated on
safe and stable slopes in accordance with OSHA regulations as discussed above. Backfill should
consist of the on-site soils or existing bedrock. If bedrock is used, all plus 6-inch material should be
14
Preliminary Geotechnical Engineering Report
Ridgeview Farms PUD
Southwest Corner of Weld County Road 35 and State Highway 392
Terracon Project No. 21055015 Terracon
removed from it prior to its use. The pipe backfill should be compacted to a minimum of 95 percent of
Standard Proctor Density ASTM D698.
All underground piping within or near the proposed structure should be designed with flexible
couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts in
grade beams should be oversized to accommodate differential movements.
GENERAL COMMENTS
Terracon should be retained to review the preliminary design plans and specifications so comments
can be made regarding interpretation and implementation of our preliminary geotechnical
recommendations. Terracon also should be retained to provide testing and observation during
excavation and grading phases of the project.
The analysis and recommendations presented in this report are based upon the data obtained from
the borings performed at the indicated locations and from other information discussed in this report.
This report does not reflect variations that may occur between borings, across the site, or due to the
— modifying effects of weather. The nature and extent of such variations may not become evident
until during or after construction. If variations appear, we should be immediately notified so that
further evaluation and supplemental recommendations can be provided.
The scope of services for this project does not include either specifically or by implication any
_ environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or
prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the
potential for such contamination or pollution, other studies should be undertaken.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, either express or implied, are intended or made. Site safety,
excavation support, and dewatering requirements are the responsibility of others. In the event that
changes in the nature, design, or location of the project as outlined in this report are planned, the
conclusions and recommendations contained in this report shall not be considered valid unless
Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing.
— 15
i
II I (WELD 0 1Y ROAD 6TATE WAY 3992 I:\P _ _ S ___
Acres — — \ -
1 I • OTS
ISM Aaes
— 74 A9 \ I LOT6 \
194 Aaea 1.64 Acres
• LOTS •
I \ B 1 . I / 1.0'11 Acres / \ \
.9-9
425p� `4760
` LOT 4 TOTAL PARCEL
11\\\ T9 / z.oz Acres
• 6334 Acres
LOT9 / \ / B-2
\ 1.95 Aaes •
— \ \ LOT3� /
LOA ID 2.a7 Aae
2114 Aaea
ORD \\ \ / LOT 1 \K\\ / LOT •
.40' 2.06 Aar •/) 2ao Acres I coil I Lf-)
�( OED ].94 Acres
\ III !(/'���� "'
•\ POND B-3 I Q
\\ \ \ 34+ acre�� \ I� 0
1 1 DT14 /
\ % LOTI2 \ . 1.9
\ 1.44 Aun N I I LL
` \ LOT 35 /
\ 2.20 Acres LOT a249-\�
\ I-
1.92A VA I I Z
LOT 13
235 Acres \ / 811;
\ \ � � I LOTJ II o
\ 217 Acres
/ \\c
\ \ \]89OAaes \ i0D Aaea LLI
/ \\'. cone\\ 1.99 Acres \
\11 \ �� LOT 22
I'... \\ \\ 5 22a Aae. Il1p
DE 54 Acre
1
LOT 19s / 2L S2 , 2116Acr 1 N •
. Y_ - � � -N
% \ ITCVE VA"/ \\\ \
LEGEND
FIGURE I: BORING LOCATION DIAGRAM
® TEST BORINGS RIDGEVIEW FARMS PUD
SW OF STATE HIGHWAY 392 & WCR 35
WELD COUNTY, COLORADO
Project Mngr. TGA Project No. 21055015
Designed By: irerracon Scale: 1..= 300'
Checked By: TGA Dote: 8/23/05
1289 FIRST AVENUE
Approved By: TGA GREELEY. COLORADO 80631 Drawn By: JSD
DIAGRAM PROVIDED BY THE CLIENT. MODIFIED BY TERRACON.
IS NOT INTENDED FOR CONSTRUCTION PURPOSES. \ Name: 21055015.dwg Figure No. 1
I 1 1 I 1 I 1 1 1 1 I I 1 1 1 1 1 1 1
1 1 1 1 ' N46'08 02 book 1409 al Pate 141,,111 29.05' N89'3904 W\980.33' .cobv ar sale coaaty.
_ = N89'39'04"W724.94' 3�•' : 493.98' 486.35' 37.94 — —
NO30.00'"E / ersexviO \fffr.:$ m
f:g..,i:: ^:..esa:msrsaoecusi T.
J \�
30.D0' aaw. 1 I .t es,A.,=
.. 111 II
49 PROP '6'Antra,CL
in L
flint'''.
II N I efi$ LOTS \ N
21
476.0
y a per deed Oda
p\ ..-) •
b 1/1]/55 in 316- TOTAL PARCEL
e[ Pa 241 4y5a NB+•atv'E 63.33A les
I i cv�oanb. Pt ,
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a� II.`` ' ,A' wix . I
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•
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� ` 1� N n
ue
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OLCILVT II Es
3.31-Acme`E
T. DEEDED PARCEL(IDSEELYLAKE)E) EDrvr. 0u CT
1 I
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LEGEND
S TEST BORINGS \
FIGURE I: GEOLOGIC SITE PLAN
KI=CRETACEOUS LARAMIE FORMATION PROPOSED RIDGEVIEW FARMS
SW CORNER OF WCR 35 & HWY. 392
-no—=PERCENT SLOPE WELD COUNTY, COLORADO
Project Mngr: TGA Project No.
Designed By: irerracon Scale: 1" = 400'
Checked By: TGA Dote: 4/4/05
1289 FIRST AVENUE
- Approved By: TGA GREELEY, COLORADO 80631 Drown By: JSD
"Note: Drawing provided by the client.Modified by Terracon.
Not intended for construction. File Name: geologic siteplan.dwg Figure No. 1
—
LOG OF BORING NO. 1 Page 1 of 1
CLIENT
Casseday Creative Designs, LLC
SITE SW Corner of WCR 35&State Highway 392 PROJECT
Weld, Colorado Ridgeview Farms PUD
SAMPLES TESTS
O
171
wa
9 DESCRIPTIONcrI m >
U w K Z Z Z_ = u) W >> cn K W z
a l- CO CO Lu O a 1 Z y O
W 0
Z } O a K m ••gOU O a Dy
cC
Approx. Surface Elev.: 4750 ft o z
`-05 TOPSOIL 47495
LEAN CLAY with SAND, stiff to very stiff, _ CL 1 SS 16 8.3
brown (CL)
CL 2 RS 15 9.4 122
5
CL 3 RS 22 10.3 113
10
%13 4737 _
WEATHERED BEDROCK, claystone,
gypsum lenses,tan/gray with iron staining
4 SS 9 31.4
i 15
— 17 V 4733 _
BEDROCK, sandstone, very hard,
brown/gray with iron staining
19.7 4730.5 - 5 SS 50/0.7 24.5,
END OF BORING
CD
0
z
0
U
Q
ll
W
The stratification lines represent the approximate boundary lines
co between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-4-05
o WL 17 WD 15.5 AB B1lerracon RORINGCCME-75ED FOREMAN 8-4-05
JSD
W
WL AB checked after 5 days. JOB# 21055015
LOG OF BORING NO. 2 Page 1 of 1
CLIENT
Casseday Creative Designs, LLC
SITE SW Corner of WCR 35&State Highway 392 PROJECT
Weld, Colorado Ridgeview Farms PUD
SAMPLES TESTS
0 p 5 ❑ Cl)
DESCRIPTION F-
>-
U = ILO
CO W W> uJ K Z ZZ
W WI-
0 3 2 )- (ice
cC o Approx. Surface Elev.: 4755 ft o D D
F t m SO o a DU)
1'4)5 TOPSOIL 4754 5
- %// SANDY LEAN CLAY, stiff, brown (CL) _ CL 1 SS 12 11.2
/ 3 4752
SILTY SAND, loose, light brown (SM)
_SM 2 RS NR 6
5 4750
CLAYEY SAND, loose, brown/light brown Y 5(SC) s
_SC 3 SS 3 25.8
10
_SC 4 SS 7 27.8
15
16 4739 _
BEDROCK, sandstone, hard, light brown —
19.8 4735 — 5 SS 50/0.8 24.0
END OF BORING
0
0
- 0
0
U<
W
F
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-4-05
WL Q 8 WD 1 5.5 AB lierracon RIG OBING CO CME-75 8
o WLJSD
� Y
WL AB checked after 5 days. JOB# 21055015
LOG OF BORING NO. 3 Page 1 of 1
CLIENT
Casseday Creative Designs, LLC
SITE SW Corner of WCR 35&State Highway 392 PROJECT
Weld,Colorado Ridgeview Farms PUD
SAMPLES TESTS
17)
DESCRIPTION 2
11J Z Z U
_ S 2 W > 0) Zuj Zz
n. F- co m CL O o O OO HZ >- 0K
D o Approx. Surface Elev.: 4745 ft o D z F 111 m 3 O o a D co
TOPSOIL
— n s SANDY LEAN CLAY, medium stiff to very _ CL 1 SS 17 9.8
stiff, brown (CL) —
_ CL 2 RS 8 14.0 114
5
/A7 4738 BEDROCK, sandstone, hard, gray/tan
3 RS 50/0.9 20.7 102
10
4 SS 45 22.0
SZ 15
19.8 4725 - 5 SS 50/0.818.5
END OF BORING
0
0
CD
0
U
ll
W
P5 The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-9-05
— o[WL 15.5 WD 9.5 AB 1lerracon R GRING C ED 8 J-05
SD
WL AB checked after 2 days. JOB# 21055015
LOG OF BORING NO. 4 Page 1 of 1
CLIENT
Casseday Creative Designs, LLC
SITE SW Corner of WCR 35&State Highway 392 PROJECT
Weld,Colorado Ridgeview Farms PUD
SAMPLES TESTS
p e o
p .
9 DESCRIPTION m z=
.t.' d' w H F- -
_ = f/) W > f/) K W Z Zz
w
7 Ow
O Q ¢Z K Ucc
o Approx. Surface Elev.: 4750 ft o D Z rr- m v DO ❑a D~)
�y n s TOPSOIL 4749 5
— V CLAYEY SAND, very loose to medium _SC 1 SS 14 11.9
dense, brown (SC)
5 _SC 2 RS 7
�V
_SC 3 RS 5 24.9 107
10
/j/,14 4736
WEATHERED BEDROCK, claystone, _ 4 SS 3 34.5
gray/yellow 15
17 4733 _
BEDROCK, sandstone, hard, light
brown/tan —
5 SS 50 23.0
20 4730 20
END OF BORING
0
0
0
z
0
U
Q
K
—
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 8-4-05
WL 8 WD 6 AB lIèrr acon RIG ING CO CME 75EFFOREMAN $ JSD
o W L AB checked after 5 days. JOB# 21055015
,
LOG OF BORING NO. 5 Page 1 of 1
j CLIENT
Casseday Creative Designs, LLC
— SITE SW Corner of WCR 35&State Highway 392 PROJECT
Weld, Colorado Ridgeview Farms PUD
SAMPLES TESTS
o DESCRIPTION m > w -
CL w Zx
.... 2 = N m > CO W I- Z o Z
K W CO 3 w
} WW iu O a0 [two Zi
O Approx.Surface Elev.: 4740 ft O D Z H r< m 3 O o o. DO
n 5 TOPSOIL _alga
CLAYEY SAND, loose to medium dense, —SC 1 SS 13 7.6
brown to light brown (SC)
_SC 2 RS 12 113 118
5
.- - . 4730.5/95 - 3 RS 10 14.5 114
- SILTY SAND, loose, tan with minor iron 10
11 staining (SM) 4729
WEATHERED BEDROCK, sandstone, 1 —
tan —
14 4726 —
BEDROCK, SZ _ 4 SS 31 24.8
—
sandstone/siltstone/claystone,firm, 15
tan/gray with iron staining —
— 17 4723 _
BEDROCK, sandstone, hard, gray/tan
19.9 4720 - 5 SS 50/0.9 25.2
END OF BORING
F-
0
0
- z
0
U<
K
K
W
- E- The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
R.
WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-9-05
IL
L Y 145 WD Y11.5 AB1 rerracon RIGBORING C CME55ED FOREMAN8 J-05
L AB checked after 2 days. JOB# 21055015,
-' -6
-5
-4
-3
-2
-1
co
-- z
co
1
2
3
4
5
6
0.1 1 10
PRESSURE,KSF
Specimen Identification Classification Yd, pcf WC,%
• 1 9.0ft LEAN CLAY with SAND(CL) 113 10
_ o
Notes: Water added at 0.5 ksf.
CONSOLIDATION TEST
ir Project: Ridgeview Farms PUD
erracon Site: SW Corner of WCR 35& State Highway 392 Weld, Colorado
o Job#: 21055015
w U
Date: 8-23-05
-6
-5
-4
-3
-2
-1
z
I
0)
J
w v
1
2
3
4
5
6
0.1 1 10
PRESSURE,KSF
Specimen Identification Classification t, pcf WC,%
• 3 9.0ft SANDSTONE 102 21
z
O
Notes: Water added at 0.5 ksf.
w
N
U,
UJ
CONSOLIDATION TEST
N Project: Ridgeview Farms PUD
z limerracon Site: SW Corner of WCR 35 &State Highway 392 Weld, Colorado
o Job#: 21055015
w 0
Date: 8-23-05
-6
-5
-4-
-3 . .
-2 _
-1
z
a
H
J
Q
1
2
3
4
'- 5
6
0.1 1 10
PRESSURE,KSF
^r Specimen Identification Classification Ya, pcf WC,%
• 5 4.0ft CLAYEY SAND(SC) 118 11
O•
z
0
Notes: Water added at 0.5 ksf.
I-
0.
dm., 0
N
YJ
r O
CONSOLIDATION TEST
Project: Ridgeview Farms PUD
1r.
acon Site: SW Corner of WCR 35 & State Highway 392 Weld, Colorado
Job#: 21055015
0
Date: 8-23-05
U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER
4 2 1 1/2,. 3 6 10 16 30 50 100 200
6 3 1.5 3/4 8 14 20 40 60 140
- 100 I I I 19 1 1
.,. 95 - -
90 - -
85 _ _
i
80 - ' -
75 .. .
70
I-
65
au• 60 - -- — —
m• 55
cc \\
— z50 1
z
45 . - 1:
w
w
40 Iii
a
35
30 - - - . -
25 - —
20 '
- i
15 --
10 - - - -
5 - -
0
100 10 1 0.1 0.01 0.001
—
GRAIN SIZE IN MILLIMETERS
GRAVEL SAND
COBBLES SILT OR CLAY
— coarse I fine coarse I medium I fine
Specimen Identification Classification LL PL PI Cc Cu
• 1 4.0ft LEAN CLAY with SAND(CL) 35 12 23
X 4 0.5ft CLAYEY SAND(SC) 28 14 14
• 5 4.0ft CLAYEY SAND(SC) 29 14 15
NI
g Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt I %Clay
— 8 • 1 4.0ft 4.75 0.0 17.6 82.4
8 m 4 0.5ft 9.525 0.115 0.7 59.0 40.4
U_
i • 5 4.0ft 4.75 0.099 0.0 51.9 48.1
H
a
_ o GRAIN SIZE DISTRIBUTION
�, Project: Ridgeview Farms PUD
lierracon Site: SW Corner of WCR 35& State Highway 392 Weld, Colorado
Job#: 21055015
0� Date: 8-24-05
GENERAL NOTES
DRILLING&SAMPLING SYMBOLS:
SS: Split Spoon- 1-3/8"I.D.,2"O.D., unless otherwise noted HS: Hollow Stem Auger
ST: Thin-Walled Tube-2"O.D.,unless otherwise noted PA: Power Auger
—
RS: Ring Sampler-2.42"I.D.,3"O.D.,unless otherwise noted HA: Hand Auger
DB: Diamond Bit Coring-4", N, B RB: Rock Bit
BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary
The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch
penetration with a 140-pound hammer falling 30 inches is considered the"Standard Penetration"or"N-value".
WATER LEVEL MEASUREMENT SYMBOLS:
— WL: Water Level WS: While Sampling
WCI: Wet Cave in WD: While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB: After Boring ACR: After Casing Removal
Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other
times and other locations across the site could vary. In pervious soils,the indicated levels may reflect the location of groundwater. In
low permeability soils,the accurate determination of groundwater levels may not be possible with only short-term observations.
—
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have
more than 50% of their dry weight retained on a#200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine
_ Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are
plastic,and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation,coarse-grained soils are defined on the basis
of their in-place relative density and fine-grained soils on the basis of their consistency.
CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS
Standard
— Unconfined Penetration or Standard Penetration
Compressive N-value(SS) or N-value(SS)
Strength,Qu,psf Blows/Ft. Consistency Blows/Ft. Relative Density
<500 <2 Very Soft 0—3 Very Loose
— 500 - 1,000 2-3 Soft 4—9 Loose
1,001 - 2,000 4-6 Medium Stiff 10—29 Medium Dense
2,001 - 4,000 7-12 Stiff 30-49 Dense
4,001 - 8,000 13-26 Very Stiff 50+ Very Dense
8,000+ 26+ Hard
RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY
— Descriptive Term(s)of other Percent of Malor Component
constituents Dry Weight of Sample Particle Size
Trace < 15 Boulders Over 12 in.(300mm)
— With 15—29 Cobbles 12 in.to 3 in.(300mm to 75 mm)
Modifier >30 Gravel 3 in.to#4 sieve(75mm to 4.75 mm)
Sand #4 to#200 sieve(4.75mm to 0.075mm)
RELATIVE PROPORTIONS OF FINES Silt or Clay Passing#200 Sieve(0.075mm)
Descriptive Term(s)of other Percent of PLASTICITY DESCRIPTION
constituents Dry Weight
Term Plasticity Index
Trace <5 Non-plastic 0
With 5-12 Low 1-10
Modifiers > 12 Medium 11-30
High 30+
-
lierracon
Form 108-9-00
GENERAL NOTES
Sedimentary Rock Classification
DESCRIPTIVE ROCK CLASSIFICATION:
- Sedimentary rocks are composed of cemented clay, silt and sand sized particles.The most
common minerals are clay, quartz and calcite. Rock composed primarily of calcite is called
limestone; rock of sand size grains is called sandstone,and rock of clay and silt size grains
is called mudstone or claystone,siltstone,or shale. Modifiers such as shaly,sandy,dolomitic,
calcareous,carbonaceous,etc.are used to describe various constituents.Examples: sandy
—
shale; calcareous sandstone.
LIMESTONE Light to dark colored,crystalline to fine-grained texture, composed of CaCo3, reacts readily
with HCl.
—
DOLOMITE Light to dark colored, crystalline to fine-grained texture, composed of CaMg(CO.)2, harder
than limestone, reacts with HCI when powdered.
CHERT Light to dark colored,very fine-grained texture, composed of micro-crystalline quartz(Si0:),
— brittle, breaks into angular fragments, will scratch glass.
SHALE Very fine-grained texture, composed of consolidated silt or clay, bedded in thin layers.The
unlaminated equivalent is frequently referred to as siltstone, claystone or mudstone.
SANDSTONE Usually light colored,coarse to fine texture,composed of cemented sand size grains of quartz,
—
feldspar,etc.Cement usually is silica but may be such minerals as calcite, iron-oxide,or some
other carbonate.
CONGLOMERATE Rounded rock fragments of variable mineralogy varying in size from near sand to boulder size
— but usually pebble to cobble size(1/2 inch to 6 inches).Cemented together with various cemen-
ting agents. Breccia is similar but composed of angular, fractured rock particles cemented
together.
PHYSICAL PROPERTIES:
DEGREE OF WEATHERING BEDDING AND JOINT CHARACTERISTICS
- Slight Slight decomposition of parent Bed Thickness Joint Spacing Dimensions
material on joints. May be color Very Thick Very Wide >10'
change. Thick Wide 3' - 10'
Moderate Some decomposition and color Medium Moderately Close 1' - 3'
Thin Close 2" - 1'
change throughout.
Very Thin Very Close .4" - 2"
High Rock highly decomposed,may be ex- Laminated — .1" - .4"
tremely broken. Bedding Plane A plane dividing sedimentary rocks of
—
the same or different lithology.
HARDNESS AND DEGREE OF CEMENTATION Joint Fracture in rock, generally more or
Limestone and Dolomite: less vertical or transverse to bedding,
— along which no appreciable move-
Hard Difficult to scratch with knife. ment has occurred.
Moderately Can be scratched easily with knife, Seam Generally applies to bedding plane
Hard cannot be scratched with fingernail. with an unspecified degree of
— Soft Can be scratched with fingernail. weathering.
Shale, Siltstone and Claystone
Hard Can be scratched easily with knife, SOLUTION AND VOID CONDITIONS
—
cannot be scratched with fingernail. Solid Contains no voids.
Moderately Vuggy (Pitted) Rock having small solution pits or
Hard Can be scratched with fingernail. cavities up to 1/2 inch diameter, fre-
- Soft Can be easily dented but not molded quently with a mineral lining.
with fingers. Porous Containing numerous voids,pores,or
other openings, which may or may
Sandstone and Conglomerate not interconnect.
— Well Capable of scratching a knife blade. Cavernous Containing cavities or caverns,some-
Cemented times quite large.
"-- Cemented Can be scratched with knife.
- IPoorly Can be broken apart easily with
Cemented fingers.
- 1 ierracon
Form 110-6-85
- [ ,..-,
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests" Soil Classification
Group
Symbol Group Name'
— Coarse Grained Soils Gravels Clean Gravels Cu 2 4 and is Cc s 3° GW Well-graded gravel'
More than 50%retained More than 50%of coarse Less than 5%fines` Cu<4 and/or 1 >Cc>3° GP Poorly graded gravel'
fraction retained on
on No.200 sieve No.4 sieve Gravels with Fines Fines classify as ML or MH GM Silty graver'''.
More than 12%fines`
Fines classify as CL or CH GC Clayey graver"
Sands Clean Sands Cu 2 6 and 1 s Cc s 3° SW Well-graded sand'
50%or more of coarse Less than 5%Mes° Cu<6 and/or 1>Cc>3' SP Poorly graded sand'
fraction passes
— No.4 sieve Sands with Fines Fines classify as ML or MH SM Silty sand""
More than 12%fines° Fines Classify as CL or CH SC Clayey sand°""
Fine-Grained Soils Silts and Clays inorganic PI>7 and plots on or above"A"line' CL Lean Gayr"
!"- 50%or more passes the Liquid limit less than 50 PI<4 or plots below"A"line' ML Silt"'
No.200 sieve
organic Liquid limit-oven dried <0.75 OL Organic clay`"'"Liquid limit-not dried Organic silts""°
— Silts and Clays inorganic PI plots on or above"A"line CH Fat clay"
Liquid limit 50 or more
PI lots below"A"line MH Elastic Silt"`"
organic Liquid limit-oven dried Organic clay""'
<0.75 OH
— Liquid limit-not dried Organic silt""":
Highly organic soils Primarily organic matter,dark In color,and organic odor PT Peat
"Based on the material passing the 3-in.(75-mm)sieve "If fines are organic,add"with organic fines"to group name.
elf field sample contained cobbles or boulders,or both,add"with cobbles ' If soil contains z 15%gravel,add'With graver to group name.
or boulders,or both"to group name. J If Atterberg limits plot in shaded area,soil is a CL-ML,silty day.
"'-' Gravels with 5 to 12%fines require dual symbols: GW-GM well-graded slf soil contains 15 to 29%plus No.200,add"with sand"or'With
gravel with silt,GW-GC well-graded gravel with clay,GP-GM poorly gravel,"whichever is predominant.
graded gravel with silt,GP-GC poorly graded gravel with clay. L
°Sands with 5 to 12%fines require dual symbols: SW-SM well-graded If and "to groupains p 30%plus No.200 predominantly sand,add
— sand with silt,SW-SC well-graded sand with day,SP-SM poorly graded 'sandy" name.
sand with silt,SP-SC poorly graded sand with day if soil contains z 30%plus No.200,predominantly gravel,
x
add"gravelly to group name.
sCu=Dea/D10 Cc= (Dw) "PI z 4 and plots on or above"A"line.
Dm x Deo " ° PI<4 or plots below"A"line.
P If soil contains z 15%sand,add with sand"to group name. °PI plots on or above"A"line.
°If fines classify as CL-ML,use dual symbol GC-GM,or SC-SM. ° PI plots below"A"line.
10 I I I 1I
/
For classification of fine-grained
soils and fine-grained fraction
— 50 —of coarse-grained soils \�° "
; to
Equation of"A'-line A),{ •1'
a Horizontal at PI=4 to LL=25.5.
_ p40 _. then PI0.73(LL 20) ......... - O`t` _._.. ....... _._._
Equation of"U"-line °�
? Vertical at LL=l8 to PI=7, G�
30 — then P13.9(LL-8)
— g 20 G".°O�
MH or OH
10
7 ----
- 4 -- ML or OL
o
r 0 10 16 27 30 40 50 60 70 80 90 100 110
— LIQUID LIMIT(LL)
lierracon _
Form 111
Hello